Minimize Orion / EM-1

Orion / EM-1 (Exploration Mission-1)

Orion Vehicle    ESM    Development Status    Launch   Payloads   References

Orion EM-1, previously known as SLS-1 (Space Launch System-1) is NASA's first planned flight of the Space Launch System and the second uncrewed test flight of the Orion MPCV (Multi-Purpose Crew Vehicle). NASA, ESA, European and US Industry have teamed to develop the ORION spacecraft.

Under an agreement between NASA and ESA, ratified in December 2012, NASA's new Orion vehicle for human space exploration missions includes the ESM (European Service Module), based upon the design and experience of ESA's ATV (Automated Transfer Vehicle), the supply craft for the ISS (International Space Station).

ESA's industrial prime contractor for ATV, Airbus Defence and Space of Bremen, Germany, is leading a European industrial consortium, developing this vehicle on behalf of ESA and working closely with NASA's Orion US industrial prime contractor Lockheed Martin Space Systems.

Orion is the spacecraft that NASA intends to use to send humans and cargo into space beyond low earth orbit and to return them safely to Earth. It is being developed for crewed missions to cislunar space, asteroids, and then to Mars. The capsule is also planned as a backup vehicle for missions to the ISS (International Space Station). It will be launched by the NASA-developed SLS (Space Launch System) in 2018. 1) 2)

The first test flight of Orion was successfully completed in December 2014 with a Delta IV launch vehicle that launched the Orion Crew Module into a high elliptical orbit to demonstrate high-speed atmospheric Earth re-entry. This flight test did not include the ESM.

It is planned such that the Orion EM-1 flies a mission profile similar to what might be used in a future asteroid redirect mission. The un-crewed Orion travels to a lunar DRO (Distant Retrograde Orbit) mission (Figure 2), then returns on a trajectory calculated to achieve a high speed atmospheric entry on the order of ~11 km/s to demonstrate the performance and effectiveness of the Orion TPS (Thermal Protection System), as well as relevant environments prior to the first manned launch of the system. The total mission duration is 25 days (6 at destination). This will be the first flight of the ESM.

The human exploration of space is a national policy of the government of the United States. The National Space Policy directs NASA to: 3)

• Set far reaching exploration milestones. By 2025, begin crewed missions beyond the moon, including sending humans to an asteroid. By the mid-2030s, send humans to orbit Mars and return them safely to Earth.

• Furthermore, the NASA Authorization Act of 2010, a law passed by the U.S. Congress and signed by the President, states that the "long term objective for human exploration of space should be the eventual international exploration of Mars."

NASA is implementing this policy as the Journey to Mars, a journey that will be neither quick nor easy. 56 million kilometers away at its closest approach, with an atmosphere too thin for easy braking but too thick to ignore, with freezing surface temperatures, a minimal magnetic field for radiation protection, and communications delays with Earth of up to 40 minutes, Mars represents the current high frontier in human exploration.

Even though Mars is tremendously challenging, it has resources necessary for human exploration (oxygen, CO2 atmosphere, and water). These resources are critical to allow us to break the ties with Earth and become Earth Independent. The atmosphere, even though very thin by Earth standards, still provides some radiation shielding. Developing the ability to utilize the resources on Mars will be critical for the journey. We have calculated that roughly 20 mt of oxygen will be needed for the human Mars ascent vehicle to achieve orbit around Mars. Rather than carry all of the propellant and oxygen needed for a Mars ascent vehicle, we will generate that propellant from the materials available on Mars.

The challenges are too difficult to tackle all at once. Instead, NASA is breaking it down into more manageable objectives: the Earth Reliant phase, the Proving Ground phase, and the Earth Independent phase. Each phase builds upon the successes (and failures) of the previous one in a sustainable, repeatable, and in manner that allows for changes in technology or funding. In this approach NASA does not need to develop and control all aspects of the journey. NASA will utilize the private sector and international partners in critical roles of the journey and depend on these partners for successful achievement of the overall journey.

Earth Reliant: NASA is operating in the Earth Reliant phase of the Journey to Mars aboard the ISS (International Space Station) right now. The ISS, orbiting some 400 km above Earth, is mere hours away from the safety and comfort of our home planet. Aboard the space station, NASA and the other international partners are developing the technologies needed to sustain human life much farther away than 400 kilometers. A new and varied fleet of commercially produced and procured vehicles is taking over the duties of transportation of humans and cargo from Earth to ISS. NASA's investments in this area promise to create new opportunities for the development of LEO, including broader use of the ISS as an orbital science laboratory and as a demonstration platform for future commercial space facilities as NASA moves towards the Proving Ground phase.

In the Earth Reliant phase, NASA is developing the "Mars-capable" systems that will be needed for long-duration stays outside of the comfortable frontier of LEO. Currently manifested or planned experiments and demonstrations include improved long-duration life support for Mars missions, advanced fire safety equipment, next-generation spacesuit technologies, high-data-rate communications, techniques to reduce logistics, large deployable solar arrays, in-space additive manufacturing, advanced exercise and medical equipment, radiation monitoring and shielding, human/robotic operations, and autonomous crew operations.

However, these "Mars-capable" systems are not only technological, but also biological- this work includes the development and demonstration of the human systems; the countermeasures, procedures, and adaptations the crew will need to survive and thrive in deep space. NASA's Human Research Program is actively working on identifying, mitigating, and eliminating the risks of spaceflight to the human body aboard ISS, while acknowledging that some risks- like radiation- can only be fully quantified with long-duration human exposure to the environment outside the Van Allen belt. NASA astronauts and others will also gain experience on a variety of management, operations, and maintenance styles and techniques are they begin flying to orbit onboard the Boeing and SpaceX crew vehicles.

We have a lot to learn from the Earth Reliant time on ISS. We have continuously been surprised by problems that arise on ISS, especially in the life support systems. NASA performed extensive ground testing on these systems only to be surprised by their actual performance in space. For example, the water systems were much more susceptible to bio-films and blockage than ground tests showed. Carbon dioxide removal system beds have more problems with dust generation and valve fouling than anticipated. We need to discover and solve these problems on ISS before venturing into deep space with these systems. ISS is the perfect platform for these development and testing activities.

In this Earth Reliant phase- when regular interaction and management from the ground is possible - NASA and its commercial partners will continue to return benefits to humanity on Earth while developing the skills to go farther. NASA intends to begin short-duration cislunar while ISS is still operating. It is a fundamental tenant of human spaceflight that continuity of operations be persevered, in order to maintain our progress in a sustained manner.

Earth Independence will also require a new operating philosophy with our crews. Today, the ground crews often serve as an additional ISS crew member. Many robotic activities are done from the ground while the ISS crew sleeps. During space walks the ground serves as an extra set of eyes and ears for the crew. As crews move into deep space, the crews must become more autonomous. Here again, ISS is an excellent platform to practice crew independence before it is required. Time delays between Earth and ISS can be added to simulate the real time delays associated with communication distances as will be experienced at Mars distances.

Proving Ground: Aboard NASA's Orion spacecraft, astronauts will look down on Earth from a perspective never seen before. Far from the comparative hustle and bustle of the ISS- with the Earth speeding by the window, with 12-15 vehicle dockings per year, and with hundreds of government and commercial experiments running in constant communication with the ground- the Proving Ground will be a more secluded place. Beginning with missions of short duration and gradually building as experience is gained, the Proving Ground will allow NASA and its partners to practice with, innovate on, and demonstrate the technologies and capabilities needed to send humans to Mars, while remaining in a location near enough to Earth to allow for crew return (in a matter of days) and close monitoring of technology advancement. NASA recently issued a call for commercial industry to propose habitation concepts and solutions for the Proving Ground, continuing the partnership started in LEO.

Activities that have become what passes for routine in our industry- such as vehicle rendezvous and docking and EVA- will needed to be revalidated in cislunar space. The environmental, power, communications, and other systems that have been developed on ISS will be verified in the environment for which they were actually designed, far from regular resupply, and operating without the regularity of maintenance which they currently require.

Launching from the Kennedy Space Center in 2018, the first integrated flight of the SLS (Space Launch System) rocket and the Orion spacecraft, called EM-1 (Exploration Mission-1), will demonstrate NASA's commitment and capability to extend human existence to deep space. The EM-1 mission will be flown without a crew. EM-1 is designed to stress the propulsion, navigation, communication, thermal, and Earth reentry systems. The mission will be the first mission flown to a distant retrograde orbit around the Moon, which is unique in that objects in this orbit will remain there without propulsive maneuvers. Testing the systems before the crew is flown is an important technique to reduce risks with the first crew missions to this remote location. The life support carbon dioxide removal system for Orion is being operated on ISS today.

The EM-1 milestone achievement will strengthen confidence in SLS and Orion as the right system design for the Journey to Mars strategy. The systems on Orion, and future deep space habitation systems, are designed to be Mars-class systems. EM-1 and subsequent missions will take these systems from Mars-class to "Mars Ready." After a series of these missions, each increasing in duration and complexity, NASA will undertake a "shakedown cruise"- a long-duration mission using the "Mars-capable" systems, uninterrupted by outside assistance. This mission will validate the complete architecture needed to take humans to the Mars vicinity and return them to the Earth.

Earth Independent: Earth Independent systems and operations are NASA's ultimate goal for Mars or any destination for humans beyond the Earth-Moon system. While true Earth Independence is many years away, NASA is laying the foundations for human exploration now. A fleet of robotic orbiters, landers, and rovers is on and around Mars, doing increasingly sophisticated analysis and exploration. Many of these missions have experiments explicitly dedicated to categorizing the environment humans will face; the Curiosity rover has a radiation detector that was also flown on ISS, and the upcoming Mars 2020 mission will have several more human health-related experiments. Robotic exploration is human exploration, albeit from a slightly removed distance, and both programs are tightly coordinated today. A safe human exploration of Mars cannot happen without a robust robotic foundation.

While the Earth Reliant and Proving Ground phases have been vigorously pursued and evaluated, the Earth Independent phase is less detailed. This is no accident. It will take an over a decade to get humans to Mars in a sustainable manner, and it is incumbent upon the current generation not to dictate or limit the manner that future generations will explore. While we can predict may of the needs of future explorers- radiation protection, food supply, environmental control, and so on- it is foolish to believe that our proposed technological solutions will be the ones most relevant to them. Instead, NASA is pursuing a capabilities-based approach, developing what we need as we can foresee the application. It is through this long-term view that we believe we can best serve our goal and destination of expanding the human presence in the solar system. We are developing an agile and sustainable approach to deep space exploration. Just as Apollo required a different approach to system engineering and hardware development, so too will the challenges associated with Mars-class missions require a different development approach and a new type of systems engineering. NASA and the U.S. alone cannot build all of the systems and perform all of the development needed for this adventure. NASA can orchestrate the plan, but will be dependent on the private sector and international partners for key components.

Today NASA is utilizing the ambitions of SpaceX to land a vehicle on Mars to obtain critical data on the technical considerations for using a propulsive landing capability in the Mars atmosphere. NASA is assisting SpaceX by providing deep space navigation capability and communication capability in exchange for access to SpaceX's data on retro-propulsion Martian entry descent and landing data. NASA has also placed the European Space Agency in the critical path for all of its human deep space exploration capability by partnering with ESA to provide the Orion service module. The service module provides thermal control, power generation life support consumables storage and propulsion for Orion, allowing it to return to Earth from a distant retrograde orbit around the Moon. These functions are critical to keeping the crew safe on Orion.

A Marketplace Above: As NASA prepares to move beyond low Earth orbit, it is our goal to facilitate an orderly, timely, and profitable transition from government tenancy in LEO to the commercial sector. Through NASA's commercial development programs, we have already demonstrated the ability of the private sector to deploy reliable launch and return vehicles for cargo to the ISS. In the near future, we are aiming to repeat that feat by using the world's first commercially developed crew vehicles for ISS transportation. Earlier this year, with NASA's assistance, the first commercially-developed expandable module was deployed onboard ISS.

Learning the benefits and issues with expandable modules directly in flight will provide criticality data for future planning. Rather than speculating on the properties of this new technology, direct on-orbit performance will be recorded. In ISS's normal mode of operations, we see dozens of commercial payloads operating every day, from biological research to materials development to CubeSat deployment. The Center for the Advancement of Science (CASIS), NASA's chosen operator for the U.S. National Laboratory portion of the ISS, is actively developing new markets and new opportunities for companies and even industries that have never previously considered spaceborne research. The goal is to expose the private sector directly to unique properties of space for their terrestrial based processes and let them see if there is a potential revenue generating opportunity in spaceborne research and manufacturing. These private sector companies can utilize to explore and test revenue generating concepts without a major investment in infrastructure. Transportation for both cargo and crew is already available from the private sector.

At the moment, the ISS is the only system in LEO. NASA and its international partners- Canada, Japan, and Russia- have committed to operating the ISS through at least 2024 (European confirmation of support is expected later this year). NASA does not intend to continue owning and operating a LEO platform. Through the research and development onboard ISS, we are trying to help create a new marketplace for both supply and demand in LEO- one where companies that require access to LEO for research or even production contract directly with companies that can provide transportation and logistics, without government involvement. We expect many of the approaches pioneered for commercial utilization of LEO will also have applications in NASA's deep space activities. Commercialization of LEO (Low Earth Orbit) is the next frontier for private companies for both those that want to provide access and accommodations in space, and those that require the same.

The commercial LEO environment will likely be very different than ISS. It is unlikely that a facility as large and complex as the ISS will be built in LEO by the private sector. The facilities for the private sector are likely to be single purpose laboratories. The facilities could be crew tended and primarily ground operated. The facilities could also be extensions of current cargo vehicles or crew vehicles such as Cygnus, Dragon Lab or Dreamchaser. The facilities need to have low operating costs and reflect the revenue generation potential of the space research. The goal is a rich LEO research and manufacturing environment supported by a private sector transportation infrastructure.

Conclusion: It is a modern cliché to say that every generation believes they are living in a special time, with choices to be made that will positively or negatively affect the very future of humanity. It is true that the promise of Mars exploration and space commercialization has been made and broken- before, and it is tempting to believe that this time will be no different. However, we are at a point in space travel that is demonstrably unprecedented in human history. Privately developed and operated vehicles are delivering cargo to an international outpost that has been continually crewed for 15+ years, onboard which a commercial module is undergoing testing, and NASA has asked for concepts for the private sector to use the ISS to accelerate their development of revenue generation from space.

Private companies can now develop their own rockets and propulsion systems and sell them on the open market. Inside the ISS, experiments in nearly every scientific field are being conducted by commercial, industrial, and academic organizations, some of which are even looking to space as a production environment. We are also flying numerous pieces of terrestrial research equipment such as DNA sequencers. The private sector no longer needs to develop custom equipment but can fly their off-the-shelf research equipment to space. In the near future, commercial companies will begin ferrying astronauts to and from the ISS. And in public, in forums such as this, NASA is explicitly saying that not only is a commercial marketplace its desired and primary outcome for LEO, it is saying that a robust commercial space market is a fundamental building block for deep space human exploration.

Things are changing. As the Earth Reliant phase exits governmental control, NASA will take both its international and commercial partners to the Proving Ground, where we will learn to live and work farther from Earth than ever before in a sustainable manner. There is no set path for this journey to Mars- merely a set of frontiers that must be broken. There is no final frontier only the next one in front of us. We are beginning an exciting journey to move human presence off of the Earth and into the solar system.

Table 1: The NASA Exploration Program – the Journey to Mars 3) 4) 5)


Orion EM-2 is planned as a Crewed High Lunar Orbit mission no later than the end of 2021. It is planned to spend several days in lunar orbit before performing a TEI (Trans-Earth Injection) burn to begin the return to Earth. The total mission duration is expected to be 14 days maximum (4 at destination).




EM-1 - Lunar (DRO (Distant Retrograde Orbit) mission

- Qualification (uncrewed)
- Simulate asteroid redirect mission

25 days (6 at destination)

EM-2 - Crewed High Lunar Orbit mission

- Qualification (crewed)

14 days (4 at destination)

Lunar Sortie mission

- Land crew of four on the surface of the Moon
and returns them to Earth

26 days (7 uncrewed in LLO)

ISS Backup Crew Delivery mission

- Backup crew and cargo delivery to the ISS

216 days (210 quiescent)

Table 2: Overview of Orion ESM Design Reference Missions


Figure 1: Artist's rendition of the Orion EM-1 spacecraft in lunar orbit (image credit: NASA, ESA)



Figure 2: Orion EM-1 (Exploration Mission-1) design reference (image credit: NASA)



The Orion Vehicle

The Orion architecture configuration consists of the following modules: (Figures 3 and 4, Ref. 1)

• CM (Crew Module)

• ESM (European Service Module)

• CMA (Crew Module Adapter)

• SA (Spacecraft Adapter)

• SAJ (Spacecraft Adapter Jettisoned Fairings)

• LAS (Launch Abort System)

The Service Module (SM) refers to the combined CMA + ESM + SA + SAJ.

The Crew Module and ESM (European Service Module), also referred to as SM, are physically interfacing via an interface ring called the CMA (Crew Module Adapter). The ESM is attached to the CMA for the duration of the mission. Just prior to the Earth's orbit entry, the CMA separates from the CM for CMA/ESM disposal and the CM performs final reentry and landing operations.

NASA is responsible for development of the CM, CMA, SA, SAJ, and LAS elements of the Orion spacecraft. The CMA provides the structural, mechanical, electrical, and fluid interface between the CM and ESM. In addition, the CMA houses communication equipment, sublimators for thermal heat rejection, and power and data control/interface electronics. The SM is enclosed by three spacecraft adapter fairing panels (SAJ) which provide a partial load path from the CMA to SA but also protect the solar arrays, radiators, and thrusters from launch and ascent loads. The fairings will be jettisoned during the ascent phase or following main engine cut-off of the launch vehicle.

The SA (Spacecraft Adapter) provides the interface to the launch vehicle during launch. During launch and ascent, the ESM and SA will be enclosed by the SAJ. The SA attaches to the aft end of the ESM to the Launch Vehicle and includes the structural interface, separation mechanisms, and umbilical connectors for communication between the launch vehicle and the Orion Spacecraft. At launch vehicle burnout, the Orion Spacecraft separates from the SA at the ESM/SA separation plane.



Figure 3: Overview of the Orion spacecraft architecture (image credit: NASA, ESA)


Figure 4: Orion schematic layout (image credit: NASA)



Orion EM-1 CM (Crew Module)

The milestones for the Orion EM-1 mirror the path taken by the Orion EFT-1 (Exploration Flight Test-1) spacecraft. However, the Orion EM-1 will sport a number of improvements based on the experiences of the December 2014 test flight. NASA is beefing up the critical TPS (Thermal Protection System) that will protect astronauts from the searing heats experienced during reentry as the human rated vehicle plunges through the Earth's atmosphere after returning from ambitious expeditions to the Moon and beyond.

Based in part on lessons learned from EFT-1, engineers are refining Orion's heat shield to enhance the design, ease manufacturing procedures and significantly strengthen is heat resistant capabilities for the far more challenging space environments and missions that lie ahead later this decade and planned further out in the future as part of NASA's agency-wide 'Journey to Mars' initiative to send humans to the Red Planet in the 2030s.

On all future flights starting with EM-1 (Exploration Mission-1), the Orion crew module must withstand the higher temperatures and speeds experienced during return from more distant destinations such as the Moon, near-Earth Asteroids and Mars. Orion's TPS is comprised of the 5 m diameter main heat shield covering the rounded base of the capsule as well as the grid of back shell tiles bonded around the vehicle from top to bottom. 6)

Starting with EM-1, engineers will bond Orion's thermal protection system back shell tiles with a silver, metallic-based thermal control coating. The coating is designed to keep Orion's back shell in a temperature range from approximately -65 to 290ºC prior to entry and afford protection against electrical surface charges in space and during reentry.

The pressure vessel is the primary structure of Orion's crew module and is made of seven large aluminum pieces that must be welded together in detailed fashion. The first weld connected the tunnel to the forward bulkhead, which is at the top of the spacecraft and houses many of Orion's critical systems, such as the parachutes that deploy during reentry. Orion's tunnel, with a docking hatch, will allow crews to move between the crew module and other spacecraft. 7)

Orion's pressure vessel is composed of seven large pieces of aluminum, three of which are the cone panels. The pressure vessel holds the atmosphere astronauts will breathe against the vacuum of deep space, forming the crew compartment. The three panels together form the angled mid-section around the crew module where the windows and hatch are located. While technicians have been joining other elements of the structure together since early September, the cone panels have presented a unique challenge for NASA and Lockheed Martin, the agency's prime contractor for Orion. Engineers who have sought to reduce the crew module's overall weight have encountered and overcome technical challenges. 8)

The lessons learned from the EFT-1 mission are being applied to the EM-1 (Exploration Mission-1) and EM-2 flight test configurations to optimize a system design that can smoothly transition into production.

Ten of the most important lessons from EFT-1 focused on the ability to evaluate the design with actual flight performance. This was critical for the remaining design process as NASA continues to develop the most advanced Human rated spacecraft ever built. The following are the top ten lessons learned from this test flight: 9)

1) Some deep space designs are classic for a reason: Every aspect of Orion's design is driven by crew safety. Over 50 years of NASA's investment learning the ins and outs of human spaceflight has provided direction for meeting deep space requirements. An example is LAS (Launch Abort System). About 6 minutes into launch, the LAS is jettisoned to save mass for the journey to deep space destinations. While other system configurations exist, design trade studies repeatedly highlighted the advantage of not carrying extra weight past the time it is needed. So because the Orion LAS supports missions to deep space, mass is king and any extra weight is an extreme hindrance to those missions. By shedding the Orion LAS early, this mass isn't a burden to the vehicle for the entire mission, and other Orion systems are able to provide the abort function for the remainder of ascent to orbit.

2) Crew safety is built in, not bolted on: The EFT-1 tested and verified systems that are built "into the bones" of the spacecraft from the very beginning. This means not just the heat shield or the flight computers are designed for the rigors of deep space, but everything included in the fundamental systems and structure of the spacecraft are designed and built to specifications set forth by NASA. Every system design has a deep space requirement it is being built to right now: Orion's seats are being designed to help prevent loss of consciousness as astronauts experience up to 5 G's during high-velocity re-entries, the cooling system keeps the crew cabin about 25ºC despite its heat shield being heated to 2,200ºC during reentry, the built in stowage lockers are designed to double as a safe-haven during dangerous solar activity, the life support system allows for exercise since deep space missions require much longer stays in zero gravity, computers and avionics are designed to self-correct in case there is a failure and you're months from home, and the crew module tiles are designed to protect from multiple micro-meteoroid strikes since the number of strikes will increase during missions that last months instead of days.

3) Reusability must be tied to reality: Part of flying for the first time in space is being able to make informed decisions about what we can realistically reuse following a deep space mission. After evaluating areas of water intrusion and corrosion, we've come to expect that many components in the crew module, especially inside the pressurized volume, or the hull where the crew sits, can be reused for later flights—components such as the computers, avionics and electrical distribution for example. The structure itself is more difficult to predict for reuse base on the unpredictable landing loads it might experience from a long journey from deep space with unpredictable landing sea conditions. The program is looking at options for reuse based on actual landing load data provided.

4) Designs mature as we Learn: Significant design changes are being made to optimize the EM vehicles. Thefuture design and analysis efforts will be simplified (Figure 5), overall mass has gone down, and recurring costs for production will be lowered. Establishing a common design philosophy has prevented a large number of engineering revisions and hardware changes. The Orion design is now incorporating lessons from EFT-1 and updated requirements for the crewed EM-2 mission.


Figure 5: Some highlights of the numerous design changes made as a result of the EFT-1 flight (image credit: NASA, Lockheed Martin)

5) Test like you fly to ensure success: After extensive testing on the ground in "Flight Like" scenarios EFT-1 successfully tested Orion in real flight environments, which could not be duplicated in ground simulations. The systems were subjected to the most critical crew safety requirement with the same rigors they will see when carrying humans. Systems verified included: thermal protection system, hardware separation events and the parachute system. This was a 100% mission success. 87 EFT-1 flight test objectives were identified in the early phases of the test development program. These objectives included verification of Orion's subsystems ability to launch, control its trajectory with OFI (Operational Flight Instrumentation), complete all separation events, reenter the Earth's atmosphere at 32, 200 km/hr and 2200ºC, land accurately in the Pacific Ocean and be recovered without damage. 81 of the 87 FTOs (Flight Test Objectives) were fully satisfied with six being partially met. Four of the seven FTO's were related to suspect DFI (Developmental Flight Instrumentation) performance. Two FTO's related to the Crew Module Up-righting System were partially met, and one FTO related to structural measurements was partially met.

6) Organize for focus: Organizationally, Lockheed Martin and NASA agreed assigning a "mission director" to each test flight would allow program focus on the near term test milestones while maintaining a parallel program focus on the remaining DDT&E (Design, Development, Test, and Evaluation) efforts. EFT-1 was the first mission where this was implemented and proved to ensure the test was completed on time and within budget. This effort also saved over one year of development time for EM-1 by performing this in parallel versus chronologically.

7) Processes and reviews tailored: Since its inception the Orion program has spent significant time focusing on defining an efficient set of requirements to enable the design of Orion as well as optimize the concept of operations for a recurring program rhythm. In an effort to remain flexible the program continues to evolve the requirements based on lessons learned. On EFT-1 the program used a consolidated requirements document approach that was successful in limiting the number of requirements, individual requirements documents, and tiers of requirements documents. The team is using the success of this approach to streamline the EM requirements where possible. Requirements verifications were completed later than planned, partly because the verification work did not carry the same urgency as other launch campaign tasks. The team is looking at a more structured "waterfall" approach to prevent lower level verifications from conflicting with launch campaign activities.

8) Flexibility to accommodate change: Several program planning improvements were accomplished during the course of the program leading up to EFT-1. Improving the Orion IMS ( Integrated Master Schedule) by integrating the NASA "non-Prime" elements improved the continuity of the entire schedule past vehicle delivery. Through Monthly Orion Program Performance Review meetings, the assessments team continued to monitor the contractor performance. Data input for these reviews consisted of Integrated Master Schedule updates, CPRs (Cost Performance Reports), Financial Management Reports (533 inputs), contractor supplemental financial and schedule data, and through participation in the subsystem IPT (Integrated Product Team) meetings. The assessments team integrated these data each month to update the assessment and forecast for the EFT-1 launch date and financial position enabling program management to make rapid decisions.

9) Partnerships ensure Communication: After the President's proposed cancellation of the Constellation program, NASA and Lockheed Martin recognized reductions needed to occur both on the government side and within Industry to keep the program intact. NASA identified all work within their scope as "Non-Prime" and all work within Industry as "Prime". NASA and Industry were challenged with a $738.9 M reduction in funding in 2010 and needed to re-plan the entire program in anticipation of this reduction. The cost reduction initiatives they initiated have come to be known as "The streamlining of Orion" and have been used as examples of how NASA and Industry can work together to become more efficient and affordable. The continued emphasis on meeting program objectives within the government's affordability range have resulted in a refined program plan that accomplishes all of its goals within the annual budget and without jeopardizing mission success. One example of this was the reduction of test flights from seven to four while maintaining the same requirements verifications.

10) Supply Chain must remain healthy: EFT-1 provided the Orion team the ability to exercise 80% of the supply chain that will be utilized for future production vehicles. This includes subcontractors currently spread across 42 states with 60,000 parts being received by NASA or its prime subcontractor in 3 major integration facilities. Throughout this endeavor the processes were validated, enhancements were made and opportunities for improvement identified. EFT-1 helped establish 6 key principles needed to ensure effective supply chain management:

• Centralized supply chain ownership/management offers advantages over IPT ownership

• Need for timely actionable information, including stable engineering design documentation, is mandatory

• Consistent, effective and constant communication is mandatory

• Management of the supplier certification and work load

• Manage with the tools, don't expect the tools to manage

• Work within the system.

In summary, NASA and Lockheed Martin are taking what we have learned from EFT-1 and years of government investments to make improvements, fly again, making improvements again, and developing a spacecraft that we can proudly stand behind and say we are confident in its abilities to take humans into deep space and bring them safely home.



Some examples of Orion design changes as a result of lessons learned from EFT-1 deals with the structure of the EM.

The Orion design for future Exploration Missions experienced many design optimizations as a result of the EFT-1 flight results. The following section highlights several changes to exemplify optimizations that was realized. Note: (For more information, the reader is referred to Ref. 9).

Structures: Reduced parts and weld assemblies required on the pressure vessel include:

- Reduction from 6 to 3 cone panels, and reduction of cone section welds from 12 to 3.

- Reduction from a 3 piece welded aft bulkhead design to a single spun-formed design.

- Change to an "Apollo-gusset" design in the aft-bay to help reduce the number of separable-parts, and combine structural elements (reduced thruster pod support structures and harness support structures, etc.).


Figure 6: A simplification and reduction of structural parts has been realized by the lessons from EFT-1 (image credit: NASA, Lockheed Martin)

Propulsion: Tubing subassemblies on EFT-1 were custom fit for propulsion system integration (e.g. fit-up tube assembly, cut, face, install heaters / temp sensors, reinstall, repeat as required). On EM-1 no trim to fit will be required on the vehicle. Tubing subassemblies will be delivered in their net shape and subassembly welds will be proof & leak tested prior to delivery.

PCAs (Pressure Control Assemblies) on EFT-1 required a custom fit for propulsion system integration (similar to Tubing subassemblies). On EM-1 there will be improved packaging and attachment methods including PCA welds proof & leak checked prior to delivery.

Propellant and Pressurant Tanks on EFT-1 were difficult to integrate and perform welding operations. The EM-1 design created a new inlet / outlet orientation to ease integration and welding operations.

RCS (Reaction Control System) thrusters on EFT-1 had support struts that have been simplified to a Pod design and attachment method eliminating all struts.


Figure 7: Left: EFT-1 Roll Left Thruster, Right: EM-1 Roll Left Thruster Pods (image credit: NASA, Lockheed Martin)

TPS (Thermal Protection Systems): The Heatshield Avcoat design improvement included changing from a monolithic, individual cell injection process to a "Block Avcoat" design where the heat shield blocks could be automated in production while increasing material properties performance. The use of thermal tape that was used on the EFT-1 heatshield (and similar to Apollo) was changed to use on all backshell and heatshield surfaces for all future Exploration Missions.

Micrometeoroid and Orbital Debris Performance: There are a number of lessons learned in the realm of MMOD (Micrometeoroid and Orbital Debris) environments and analyses, which are being examined and used to influence change for the EM and beyond missions. Chief among these lessons learned is that time spent in the high orbital debris flux altitude band, approximately 650 km to 1200 km, should be minimized. The MMOD analysis performed on EFT-1 was the first such analysis of a human-rated spacecraft above ISS ( International Space Station) altitudes since man-made orbital debris has become an issue, and found the risk at these altitudes (600 km – 1600 km) to be much higher than anticipated; Apollo was too early in spaceflight history for much OD (Orbital Debris) to have accumulated yet. Post-flight inspection of the EFT-1 capsule indicated that actual MMOD exposure may have been even higher than the analyses had assessed. Based on this lesson learned, the parking orbit of EM-1 has been reduced from 3.5 hours in a high-MMOD-risk orbit (2 orbits), to half that time (limited to 1 orbit) to reduce MMOD risk. And as EM-2 trajectory trades and analysis is ongoing, avoiding these altitudes has been accepted as a prerequisite in the EM-2 trajectories. Largely anchored on this finding, other lesson learned recommendations include: increasing MMOD protection in upper-stage and other critical hardware, re-assessing window damage cause and remediation, and continued post-flight inspections and MMOD environment recommended updates based on EM flights.

Radiation Summary: Orion is the first spacecraft that addresses crew radiation protection as an integral part of the vehicle design. We are using a state-of-the-art radiation analysis process to analyze the shielding provided by the vehicle and quantify the internal radiation environment. This analysis is based on the full fidelity Orion CAD model and space radiation environment models. Due to the EFT-1 trajectory passing through the very core of the van Allen proton belts, intravehicular radiation environment was equivalent to 4-6 weeks inside ISS (in terms of cumulative exposure). Thus EFT-1 presented a valuable opportunity to validate our analysis procedure and ultimately improve crew radiation protection for future manned missions. This opportunity was materialized by flying six RAMs (Radiation Area Monitors) on EFT-1. Radiation measurements were in very good agreement with pre-flight predictions, confirming the validity of the radiation analysis approach and providing confidence in our efforts to maintain crew radiation exposure ALARA (As Low as Reasonably Achievable) consistent with NASA requirements.

An important lesson learned for electronic components radiation hardening refers to the importance of considering time variability of the environments in the Single Event Effect rate calculations. The EFT-1 proton environment varied dramatically throughout the mission. Accounting for this time variation was an essential component in selecting the appropriate level of redundancy in critical systems such as the VMC/FCMs (Vehicle Management Computer / Flight Control Modules). This lesson continues to apply to Exploration Missions. Stochastically occurringSPEs ( Solar Particle Events) may cause significant temporary increase in the radiation environment, and critical systems need to design appropriately. A related lesson learned reflects the importance of assessing timing of critical mission events with respect to the radiation environment. Environment assessments performed for EFT-1 drove modification of the mission timeline such that Avionics intensive mission events be executed outside of the core of the van Allen belts. This too is a lesson learned relevant for future missions especially in off-nominal conditions that may expose the spacecraft to high radiation environments.


EM-2 (Exploration Mission-2): EM-2 will be a crewed test flight that will be launched on an SLS and enter lunar orbit in 2021 to verify the capability of Orion to successfully launch, perform a crewed mission, and return them safely to Earth. Figure 2 depicts one option for a lunar mission. The EM-2 configuration will consist of:

• A fully functional launch abort system

• A fully functional Crew Module that includes a crew of up to four and all Cis-Lunar life support systems

• A fully functional Service Module.


Figure 8: EM-2 Design Reference Mission (image credit: NASA)


Figure 9: Technicians with Lockheed Martin, NASA's prime contractor for Orion, are welding together the pieces of the spacecraft's pressure vessel at Michoud Assembly Center in New Orleans, LA (image credit: NASA)



ESM (European Service Module)

The ESM implements four major system functions to Orion (Ref. 1):

• provides thrust for orbital maneuvers and attitude control after upper stage/launch vehicle separation

• generates electrical power and distributes it to the ESM users and to the CM/CMA

• regulates heat for the life support and avionics equipment during the orbital phases of the mission

• stores and provides to the CMA/CM potable water, oxygen, and nitrogen.

In addition, it ensures structural spacecraft integrity during launch and in-orbit maneuvers. The ESM can also provide additional volume and other resources on select missions for accommodating science, engineering demonstrations, development test objectives, and deployment of lunar infrastructure equipment during the cruise and lunar orbit phases of lunar missions. This volume provides electrical power distribution, network access for command and control interfaces, and structures and mechanisms.

The architecture of the module has been developed based on the ATV spacecraft concept (five successful missions to the ISS),modified to cope with the different mission requirements and the man-rating approach for beyond LEO missions. 10)


Figure 10: Illustration of an ATV cargo freighter in flight with deployed solar arrays (image credit: ESA)

The resulting ESM architecture is depicted in Figure 11, for comparison. The architecture of the system and subsystems hereafter proposed is the reference design for the Lunar Sortie Mission. Changes in the architecture are expected for the other missions to tailor the configuration to mission needs, to remove unnecessary HW and to optimize the launch mass.


European Industrial Consortium: ESA entrusted the development of the ESM (European Service Module) to a consortium of European industries led by Airbus Defence and Space. The consortium of companies was selected to reuse the experience and industrial heritage of the very successful ATV (Automated Transfer Vehicle). Airbus Defence DS Germany as the Prime Contractor is responsible for all system-related work. This includes: 11)

- The overall Management of the contract

- The overall System Engineering activities

- The Management of the procurement activities

- The System Product Assurance and Safety activities

- The liaison with Lockheed-Martin (NASA prime contractor of the Orion vehicle).

Airbus DS, France is responsible for part of the system engineering, ground software, Helium pressurant tanks and simulation facility.

On Subsystem level, Airbus DS, Germany is responsible for the System Engineering, the Propulsion, Power and Avionics Subsystem Engineering as well as for GSE and AIT activities. The responsibility for the development of the other sub-systems or equipment has been distributed among European companies as follows:

TAS (Thales Alenia Space) Italy: the Structure, Thermal and Consumable Storage Subsystems, supported by the following level-2 subcontractors:

- RUAG, Switzerland: secondary structures

- SONACA, Belgium: tank bulkhead

- APCO, Switzerland: MDPS (Meteoroid and Debris Protection System)

- CRISA, Spain, TCU (Thermal Control Unit)

- Prototech, Norway: nitrogen filters

- MEWASA, Switzerland, Water tank bellows.

Dutch Space, The Netherlands: the SAW (Solar Array Wings), supported by the following level-2 subcontractors:

- SELEX SE, Italy for the Photo Voltaic Assemblies

- RUAG, Switzerland: deployment dampers.

Airbus DS, Germany: the propellant tanks, Propulsion Drive Electronic and reaction control thrusters.

RUAG, Switzerland: the SADA (Solar Array Drive Assembly) composed of the mechanism and electronic unit.

SELEX SE, Italy: the PCDU (Power Conditioning and Distribution Unit)

Thales Alenia Space, Belgium: PRU (Pressure Regulation Unit)

Antwerp Space, Belgium: the Electrical Ground Support Equipment Front Ends, supported by the following level-2 subcontractors :

- Clemessy, France

- Rovsing, Denmark.

APCO, Switzerland: Mechanical Ground Support Equipment.

Latelec, France: avionics and power harness

TESAT Germany and Alter, Spain: CPP (Centralized Parts Procurement) scheme for EEE (Electrical, Electronic and Electromechanical)-parts.

Equipment suppliers encompasses Vacco (US), Moog (US), Sofrance (F), Cobham (US), Vivace (US).


Figure 11: Illustration of the ESM (European Service Module) without radiators and MDPS, image credit: ESA, Airbus DS


Physical architecture: The ESM is a cylindrical unpressurized module which interfaces at its bottom to the SA and at its top to the CMA. The OMS-E (Orbital Maneuvering System -Engine), i.e. the main engine, protrudes into the SA. Equipment on the tank platform is also allowed to protrude into the CMA. The total height of the ESM is 4.0 m.

The cylindrical shape is defined by the external radiators which enclose the body of the ESM. The function of the radiators is twofold, i.e. to radiate heat, and to serve as the first barrier of the MDPS (Micrometeoroid and Debris Protection Subsystem ). Mounted to the back side of the radiators are Nextel and Kevlar blankets which serve as the second barrier. The externally mounted RCS (Reaction Control System) pods and SAWs (Solar Array Wings) must be designed such that these respect the Orion SAJ allowable envelope.

The internal accommodation of the ESM subsystem equipment is highly dependent to the primary structure architecture, based on seven separate bays for accommodation, six located circumferentially about the central bay. The pressurant tanks are accommodated in the center bay. The four largest bays are used for the accommodation of the propellant tanks which dominate the available volume. The remaining volume provides accommodation to the avionics equipment, CSS (Consumable Storage Subsystem) water tanks, harnessing and tubing.

The top surface of the ESM is dominated by the protruding tank domes for the propellant subsystems, one of the helium pressure tanks, the four tanks for Oxygen and Nitrogen, and the Flow Control Assembly for the active cooling subsystem. These elements protrude into the CMA, while maintaining a specific minimum distance to the CM Heat Shield. For these elements above the tank platform, the CMA provides the MDPS protection.

The lower surface is dominated by the OMS-E, which serves as the main engine of the ESM, and the eight auxiliary thrusters. Within the lower platform, a panel is incorporated through which the UPC (Unpressurized Cargo) is installed, and optionally ejected.

Total launch mass

13,500 kg for Lunar Mission, including 8600 kg of usable propellant, 240 kg of potable water, 30 kg of N2 and 90 kg of O2


- ∅=5.2 m (with solar wings stored), L=4 m, deployed solar array span: 19 m
- ESM L is actually ~2 m, considering the primary structure only, but reaches up to 4 m adding the protrusions of the main engine toward the SA and the propellant / gas tanks toward CMA


380 kg (max), maximum volume of 0.57 m3

Solar array power

11.2 kW


- 1 main engine, ca. 30 kN
- 8 auxiliary thrusters, each 490 N
- 24 RCS (Reaction Control System) thrusters, each 220 N

Table 3: ESM characteristics for Lunar Missions


Functional architecture: Orion functionalities are generally shared between ESM and CMA/CM. Functional Chains gather equipment of the ESM which participate to a same service provided by Orion for the accomplishment of its mission.

Figure 12 depicts the overall avionics subsystem architecture and interfaces. The interface to the SLS launcher is depicted on the left side of the drawing, and the CM and CMA (labeled as SM-CM I/F Adapter) are on the right side. The main link with Orion CM on-board computers is the ODN (On-board Data Network), based on a time-triggered Ethernet solution. This interface ensures the connection of all ESM avionics to the on-board computers and allows the ESM to receive commands and to deliver monitors.

Few discrete lines ensure the independent command of ESM power subsystem electronics, allow to acquire signals from 8 sun sensors used as back-up AOCS sensors and allow the transfer of data acquired from the development flight instrumentation.

The four SAWs (Solar Array Wings) ensure a maximum electrical power production of 11.2 kW, to cope with a CMA/CM power demand of maximum 7.3 kW to be respected with one wing failed.

Four power buses allow powering to / from the CMA/CM depending on mission phases. Additional and independent power lines are provided for the wireless cameras installed on top of SAWs.

Finally, a dedicated pass-through harness connects the CMA to the SA/SAJ and launcher to allow transfer of monitoring data and separation commands.


Figure 12: ESM functional architecture (image credit: ESA, Airbus DS)


ESM Layout:

The ESM provides translational and 3-axis attitude control for the spacecraft, stores consumables for the crew module and provides power via the solar arrays. The ESM is also being designed to carry cargo. The main subsystems of the ESM are: 12)

• Structure Subsystem

• TCS (Thermal Control Subsystem)

• CSS (Consumable Storage Subsystem)

• PSS (Propulsion Subsystem)

• EPS (Electrical Power Subsystem)

• Avionics Subsystem


Figure 13: Top view of the ESM and its elements (image credit: ESA, Airbus DS)


Figure 14: Illustration of the ESM architecture and principal layout of main elements (image credit: ESA, Airbus DS)


Structure subsystem: The ESM astructure consists of the following major elements:

• Primary structure

• Secondary structure

• MDPS (Meteoroid and Debris Protection).

The primary structure transmits the SLS launch loads to the upper composite composed of the CMA, the CM, and the LAS, then supports the upper composite aerodynamic and inertial loads as well as the ESM inertial loads generated by the ESM internal equipment. The design is based on a shared load path between the ESM and the external SAJ fairings. The objective is to minimize the loads applied on the ESM mechanical structure in order to optimize its mass which is propelled all along the mission, whilst the SAJ capability is sized to the extent possible by the main launch phase, since the SAJ mass is jettisoned early during the launch. The primary structure is composed of:

• 6 longerons (machined aluminum) linked to the CMA frame and six pyronuts that separate the ESM from the Spacecraft Adapter

• Tank bulkhead (machined aluminum) supporting the four propellant tanks, as well as the gas delivery CSS tanks, ensuring the main link between the CMA lower interface ring and the rest of ESM structure.

• "Radial" shear webs and internal "square" webs assembly (composite sandwich panels), housing most of the ESM equipment, including water tanks and SAW support frames and propulsion high pressure system. It forms the ESM core attached to the tank bulkhead, longerons and lower closeout panels. The main engine is attached to the central square tube panels via struts transmitting the thrust.

• Lower Platform (machined aluminum) on which the equipment is connected: OMS-E main engine, auxiliary thrusters supports, RCS pods supports, SAD (Solar Array Drive) mechanism, and PIE (Propulsion Isolation Equipment).

• MDPS covers and aft closure panels to protect the ESM from the MMOD (Micrometeoroid and Orbital Debris) environment.

The secondary structures support the ESM equipment carrying the inertial and dynamic loads of the equipment during launch and transmitting in-orbit thrust and inertial loads.

The MDPS is partly metallic and partly composed of Nextel reinforced MLI (Multi-Layered Insulation). Debris and meteoroid particles with velocities up to 24 km/s hit the outer wall, forming a cloud of lower energy particles which are then contained by the inner wall, preventing any penetration of the ESM.


Figure 15: Primary and secondary structures (image credit: ESA, Airbus DS)


TCS (Thermal Control Subsystem): The TCS includes an ATCS (Active Thermal Control Subystem), a PTCS (Passive thermal control Subsystem) and the TCU (Thermal Control Unit).

11) ATCS (Active Thermal Control Subystem): The ATCS is designed to collect the thermal loads from the CM and from the ESM powered equipment and to reject them toward the space radiative sink. The ATCS architecture is based on a Single-phase Fluid Loop Architecture using the HFE-7200 coolant to collect and to transfer the heat loads from both ESM avionics (via cold plates) and CM (via Inter-Loop Heat Exchanger) and to reject them through specific body mounted radiators. The ATCS is composed of two fully independent loops working simultaneously (hot redundancy approach). The schematic of the ATCS architecture is presented in Figure 16.

Each ATCS loop is composed by the following main components:

• 1 Radiator Assembly commonly used for both loops and composed of 4 full height radiators and 2 split radiators (with lower part not removable) mounted in serial configuration

• 1 CP (Cold Plate)

• 2 online APSBs (Absolute Pressure Sensor Blocks)

• 1 wet on-line TSB (Temperature Sensor Block)

• 1 FCA (Fluid Control Assembly) including redundant pumps with relevant passive accumulator and a TWMV (Three-Ways Modulating Valve)

• Hard/flex hoses, tees, couplings and restrictors.


Figure 16: Architecture of the ATCS (image credit: ESA, Airbus DS)

The FCA is controlled by the TCU to provide constant mass flow rate inside the loop. In particular two flow rate set points are foreseen, one for nominal operation and one for contingency (with only one loop operative). The FCA also includes the TWMV, controlling the temperature at the ESM-CMA interface.

The external surface of the radiator panels is coated with a specific paint characterized by the following thermal-optical characteristics:

• Alpha (α) = 0.2

• Emissivity (ε) = 0.8.

The Cold Plates are devoted to collect the entire thermal load from the ESM avionics boxes. Their design is constituted by a stainless steel channelling enclosed in an aluminum casting acting as a plate in direct contact with the thermally active unit. Different Cold plate sizes, to satisfy the different configuration needs, are foreseen.


Figure 17: Photo of a sample radiator panel (image credit: ESA, TAS)

12) PTCS (Passive Thermal Control Subsystem): The PTCS provides the thermal control of ESM hardware (propulsion, CSS, power and avionic items) and reduces the temperature gradients and minimize heat flows through the internal elements. The PTCS has two main components, heaters (with thermistors and wire heater) and insulation (MLI thermal blankets, including some specific high temperature MLI blankets, for thrusters and engine nozzle thermal impingement protection).

The MLI protects the internal parts against the external environment and heater lines compensate the heat leaks toward space. Different MLI typologies, in terms of composition, have been identified for the different applications on the ESM. The MLI composition mainly depends on exposure or not to the space, geometry & fixation interfaces and exposure to thrusters plume flux and nozzle radiation.

Two cold redundant heater lines managed by the TCU assure thermal control and temperature uniformity in the Orion internals and for the local thermal control of specific items. In addition, heater lines managed by thermostats and powered by the PCDU (Power Control and Distribution Unit) provide a further redundancy to the environmental control function.

13) TCU (Thermal Control Unit): The TCU is designed to ensure the management of the TCS and of the CSS.

For the ATCS, the TCU acquires the various parameters from the ATCS sensors, monitors and commands the ATCS valves, and issues commands to the FCA (Flow Control Assembly).

For the PTCS, the TCU commands the heater chains and monitors the thermistors. It operates according to activation and de-activation thresholds defined and modified by the CM on-board computers, while ensuring bus interface and power supply logic.

For the CSS (Consumables Storage Subsystem), the TCU commands the valves and monitors their position. It also monitors the pressure and temperature parameters in the subsystem to support the system FDIR (Failure Detection, Isolation and Recovery).


Figure 18: Layout of the TCS (Thermal Control Subsystem), image credit: ESA, Airbus DS


CSS (Consumable Storage Subsystem): The CSS provides potable water, oxygen and nitrogen to the CM. It can also provide water for the sublimator located in the CMA via a dedicated kit composed by its own tank assy and distribution system, to be installed optionally for specific missions. It consists of the following major elements:

• WDS (Water Delivery Subystem)

• GDS (Gas Delivery Subsystem)

The architecture of the WDS is composed of the following components:

• Water tanks (metal bellow technology)

• Water on/off valves, (isolation valves)

• Temperature and quantity sensors

• 2 distribution lines towards the CMA I/F to supply water for the different CM/CMA needs.

The architecture of the GDS is composed of the following components:

• Gas tanks

• Gas pressure regulators

• Gas on/off valves, (isolation valves)

• Gas relief valves

• Temperature and pressure sensors

• Hydrophobic filters upstream the water tanks

• Distribution lines towards the CMA I/F to supply oxygen and nitrogen

• Distribution lines towards CMA I/F for GDS filling on ground from the GSE.

In the case of a configuration with WSK (Water Sublimator Kit) a set of 3 additional water tanks is introduced and interconnected to the others tanks and lines of CSS.


Figure 19: Layout of the CSS (image credit: ESA, Airbus DS)


PSS (Propulsion Subsystem): The propulsion subsystem design has to cope with a complex mission scenario. It includes three different types of engines / thrusters. Each of these thrusters utilizes the same propellants: MON-3 (Mixed Oxides of Nitrogen) as oxidizer and MMH (Monomethylhydrazine) as fuel.

The single Main Engine, which is one of the Shuttle OMS-E engines (27.7 kN), is delivered by NASA as GFE (Government Furnished Equipment) and will be used during ascent abort and trans-earth injection maneuvers as well as orbit change maneuvers. This engine is gimballed with an amplitude of ± 7° around both axes (pitch and yaw). The actuation is performed by the TVC (Thrust Vector Control).

The 8 auxiliary thrusters which are similar to those used on ATV (490 N) are used during ascent abort and launcher separation together with the main engine. They are also used as backup to the main engine for trans-earth injection and for trajectory correction maneuvers.

The 24 RCS thrusters which are the same as used on ATV (220 N) provide the impulse necessary for attitude control, small maneuvers and forced translation during Rendezvous and Proximity operation. These thrusters are accommodated into six pods. Two pods are composed of four roll thrusters, placed along the ESM lateral surface under the CMA, while four other pods are composed of four thrusters, placed along the ESM lateral surface under the level of the first four pods. Each propellant type is stored in two propellant tanks, both sets of propellant tanks being arranged in a series configuration.

The propellant distribution comprises several electromechanical valves for propellant isolation and pressure transducers interconnected via pipes. The assembly ensures isolation of the engine / thrusters from the propellant tanks during launch, docked phase to the ISS and other mission events where it becomes necessary to isolate the engine / thrusters from the propellant storage. The propellant distribution network provides the connections between the propellant tanks and the isolation valves and then onwards to the thruster assemblies. Fill and Drain Valves and the related access lines are used during ground testing and for loading and unloading of the propellant and pressurized tanks. They are located in the CMA to enable access even after the SAJ around the service module has been installed.

The propulsion subsystem is controlled by the PDE (Propulsion Drive Electronics) which handles all nominal propulsion related commands issued by the CM and provides feedback via the CMA PDUs (Power Distribution Units) and the PDUs to the vehicle management computer interface and the ESM network. The PDE controls all thrusters, the TVC and the associated valves, instrumentation and leakage detection.

The PRU (Pressure Regulation Unit) controls and monitors the operation of the pressure regulation valves, based on set points defined and modified by the on-board computers. The EPR (Electronic Pressure Regulation) selected for ESM has the advantage to optimize the pressure of propellant and oxidizer according to the engine in operation, at the price of an increased development risk for this function.

The EPR of the propulsion system propellant is a new technology for the European industry. The ATV design featured a mechanical pressure regulation like the propulsion system of the Shuttle OMS-E engine. The electronic pressure regulation allows a better control of the pressure, hence the fuel and oxidizer consumption is enabling to reduce propellant margins and the overall mass at launch. Airbus DS decided to venture in that new technology as a result of a trade-off taking into account the positive results obtained by Lockheed-Martin in breadboard testing. However, in the development of a new technology there is always the risk of not being successful especially if the development time is constrained.

To mitigate the impact to the project in case of unsuccessful development, it was decided to ensure that reverting to mechanical pressure regulation would be possible with minimum schedule impact. NASA provided Shuttle mechanical pressure regulators and valves to VACCO, the original manufacturer and Airbus DS ordered tests to ensure the hardware would satisfy the performance required for the ESM. Breadboard testing of the electronic regulation performed in Europe up to now delivered promising results and the probability of having to revert to mechanical pressure regulation is becoming more remote.


Figure 20: Layout of the propulsion subsystem (image credit: ESA, Airbus DS)


EPS (Electrical Propulsion Subsystem): The EPS has the function to generate the power for all modules of Orion. It manages the power provided by its 4 SAW (Solar Array Wings). The PCDU (Power Control and Distribution Unit) provides the power I/F to the SAW and CMA, distributes electrical power to ESM users and protects the power lines.

The power generation part of the ESM EPS consists of four SAW units. Each wing is composed of three deployable CFRP (Carbon Fiber Reinforced Polymer) rigid panels covered with triple junction GaAs solar cells forming nine (9x) sections of solar cell strings. In nominal condition the SAW can supply a total 11.2 kW. Each SAW is linked to the ESM structure by a two degree of freedom SADA (Solar Array Drive Assembly). The SADA ensures the power and signal transfer from the SAW to the PCDU. It is composed of SADM (Solar Array Drive Mechanism) and a (SADE (Solar Array Drive). The SADM allows orienting the SAW in two independent axes. In the Sun-tracking mode the inner axis can swivel between -35º and +25º, while the outer axis has a continuous rotation capability (0º; +360º).

SADM of the ESM has a unique design incorporating a two axis gimbal. An inner axis provides rotation of the SAW about an axis perpendicular to the ESM longitudinal axis, and an outer axis which rotates the SAW about its own longitudinal axis. The two-axis capability is necessary for two reasons:

1) allow maximum sun tracking to meet the power requirements for particular vehicle attitudes of certain mission phases. Insufficient power is generated by the SAW with a single (roll) axis SADM not providing the avoidance capability of the shadowing effect of both the Orion vehicle on the SAW and the SAWs on each other

2) insure the structural integrity of the SAWs under injection maneuvers. For the trans-lunar injection performed with the upper stage of the Space Launch System rocket, actually the iCPS (interim Cryogenic Propulsion Stage), the arrays are canted backwards to sustain in deployed configuration the 1 g acceleration load. For the trans-earth injection performed with the ESM main engine, the acceleration is less severe and the arrays have to be canted forwards to prevent damages from the OMS-E engine plume while minimizing the load on the SAWs.

The SADM also allows repositioning (canting) of the SAW to reduce the loads on the SAW and SADM during the different Orion orbital maneuvers. At TLI (Trans-Lunar Injection), a 0.5 g acceleration is generated by the iCPS engine and at LOI (Lunar Orbit Insertion) and TEI (Trans-Earth Injection) a 0.3 g deceleration is generated by the OMS-E engine.

As shown in Figure 21, in order to reduce these loads to an acceptable level, the SAWs need to be repositioned by the SADM. In TLI, the SAWs are thus canted during the maneuver to inner axis = - 60º / outer axis = 0 º. In LOI/TEI, the SAWs are canted to inner axis = +55º / outer axis = 0º.


Figure 21: Orion vehicle with ESM SAW canting angles (-60º / 0º @ TLI, +55º / 0º @ LOI/TEI), image credit: ESA, Airbus DS

The EPS distributes the generated power to the CMA/CM through four independent 120 V busses. The power interfaces of the PCDU protect each unregulated bus from overload or short circuit failures on feeder busses outside the PCDU. They are implemented with power devices connected in parallel and independently operated for power flow from PCDU to CMA PDU, plus a number of power diodes for power flow from CMA PDU to PCDU.


Avionics Subsystem: The high-level management of the vehicle and its functions is performed at the level of the Orion on-board computers. The ESM is controlled and monitored by specific electronic controller units. All units are connected via the ODN (Onboard Data Network) to the CMA/CM. All vehicle control and management software resides in the CM computers. The ODN is a three plane TTGbE (Time Triggered Gigabit Ethernet),1000Base-CX, according to standard SAE AS6802.

The Time-Triggered Gigabit Ethernet ODN provides a set of time-triggered services implemented on top of standard IEEE802.3 Ethernet. It provides the capability for deterministic, synchronous, and congestion-free communication, unaffected by any asynchronous Ethernet traffic load. By implementing this standard in network devices (network switches and network interface cards), Ethernet becomes a deterministic network. This means that distributed applications with mixed time-criticality requirements (e.g., real-time command and control, audio, video, voice, data) can be integrated and coexist on one Ethernet network.

Each of the ESM controller units is connected via a SNIC (Standard integrity Network-Interface Card), according to Honeywell ICD8273722, to the LAN switch located in the CMA. The SNICs have three ports for two failure-tolerant communication on three network redundancy planes.


Development: The challenging schedule of the program, with the ESM delivery planned for early 2017 and the EM-1 launch planned for 2018, is influencing the way the ESM is verified. Qualification has often to run in parallel to EM-1 flight model manufacturing and integration, bringing risk to the program. This risk is carefully monitored and risk reduction strategies are in place to ensure the program can proceed smoothly. The ESM verification is mostly accomplished at module level. A limited number of verifications is planned on the EM-1 flight model.

- The system PDR (Preliminary Design Review) was successfully concluded in the summer 2014.

- The system CDR (Critical Design Review) is scheduled for the end of2015 and will conclude with the board in February 2016.

• The decision to include an International Partner in the development of Orion is beneficial for NASA, enlarging the cooperation on human explorations and strengthening the international partnership.

• ESA also benefits of the ESM program because it allows to retain in Europe the experience acquired with ATV program, to participate to the exploration endeavour, and to develop additional capabilities for use toward future ESA missions.

• Both NASA and ESA, together with their industrial partners, are committed to that goal of achieving the program objective in spite of the complex interface management needed and of the challenging schedule.

Table 4: Summary of key aspects for an international partnership in the Orion program



Development status of Orion EM-1 (Exploration Module-1) and ESM (European Service Module):

• October 12, 2017: While engineers in Europe continue to outfit the Orion spacecraft's service module for EM-1 (Exploration Mission-1) in preparation for shipment to NASA's Kennedy Space Center in Florida next year, work is already beginning on the service module that will power, propel, cool and provide air and water for the first crewed mission in the Orion spacecraft in the early 2020s. Technicians at Thales Alenia in Turin, Italy, are working on the primary structure of the European Service Module that will carry astronauts in Orion beyond the Moon during EM-2 (Exploration Mission-2). ESA (European Space Agency) and its contractors are providing Orion's service module for its first two missions atop the Space Launch System rocket. NASA is leading the next steps in human space exploration and will send astronauts to the vicinity of the Moon to build and test the systems needed for challenging missions to deep space destinations including Mars. NASA is working with domestic and international partners to solve the great challenges of deep space exploration. 13)


Figure 22: Work progresses on Orion Powerhouse for Crewed Mission (image credit: NASA, Rad Sinyak)

• August 24, 2017: Engineers at Lockheed Martin and NASA breathed life into the next Orion crew module when they powered up the spacecraft for the first time at the Kennedy Space Center, Florida. Designed for human spaceflight, this Orion will be the first to fly more than 60,000 km beyond the Moon during its nearly three-week EM-1 (Exploration Mission-1), a feat that hasn't been possible before. 14) 15)

- "Orion was designed from the beginning to take humanity farther into space than we've ever gone, and to do this, its systems have to be very robust and reliable," said Mike Hawes, vice president and Orion program manager at Lockheed Martin. "Over the last year, we've built great momentum in assembling the crew module for EM-1. Everyone on the team understands how crucial this test campaign is, and more importantly, what this spacecraft and mission means to our country and future human space flight."

- The initial power-on event was the first time the vehicle management computers and the power and data units were installed on the crew module, loaded with flight software and tested. Evaluating these core systems, thought of as the "brain and heart" of the Orion capsule, is the first step in testing all of the crew module subsystems.

- Although astronauts will not fly in this capsule on this flight, a large majority of the subsystems and avionics are the same design that astronauts will rely on during following missions with Orion into the solar system. Launching on NASA's Space Launch System — the most powerful rocket in the world — the EM-1 flight is critical to confirming the Orion spacecraft and all of its interdependent systems operate as designed in the unforgiving environment of deep space.

- With the successful initial power on behind them, engineers and technicians will now continue integrating the 55 components that make up the spacecraft avionics suite, connecting them with nearly 400 harnesses. Over the course of the next two to three months, as each system is installed, they will perform thorough functional tests to ensure Orion is ready to move to the all-important environmental testing phase.

May 12, 2017: NASA managers have ruled out putting a crew on board an Orion capsule atop the agency's huge Space Launch System rocket for the gargantuan booster's maiden flight in 2019, citing technical risks and higher costs, up to as much as $900 million, agency officials said at a news conference on May 12, 2017. 16) 17)

- In February 2017, the Trump administration asked NASA to look into the possibility of either adding a crew to the EM-1 (Exploration Mission 1), or moving up the launch of EM-2, the flight NASA already earmarked for the SLS (Space Launch System) booster's first piloted mission. That flight is targeted for launch in the 2021 timeframe. 18)

- The NASA study concluded that while it would be possible to upgrade the Orion spacecraft to accommodate a crew for the EM-1 flight — equipping it with life support systems, crew displays, a validated launch abort system and other critical elements — it would have required an additional $600 million to $900 million in funding. - And there would be additional technical risk and likely delays to accelerate software development and to retrofit the EM-1 Orion capsule to support a two-person crew.

- As a result, acting NASA Administrator Robert Lightfoot said agency managers and White House officials agreed it made more sense to stick with the original plan, launching an uncrewed Orion capsule atop the first SLS booster in 2019, followed by a piloted mission using an upgraded version of the rocket two years later.

- And so, NASA will stick with plans to launch a "Block 1" SLS rocket in 2019 to boost an unpiloted Orion capsule on a three-week flight beyond the moon and back to a high-speed reentry and ocean splashdown.

- The launch date recently slipped from late 2018 to 2019 — the exact date is TBD — because of a variety of factors, including manufacturing delays caused by recent tornado damage at the Michoud Assembly Facility near New Orleans where the SLS rocket is being built.

- In any case, EM-2, featuring an astronaut crew, would be launched atop a Block 1B SLS rocket in the late 2021 timeframe. Unlike the EM-1 rocket, the Block 1B version of the SLS would feature a more powerful, human-rated EUS (Exploration Upper Stage).

- The long-range plan is to use the SLS to send astronauts beyond the moon in the mid 2020s before eventual flights to Mars.

- The long gap between the SLS's initial test flight and the piloted EM-2 mission, driven in large part by NASA's budget and a variety of technical hurdles, has raised concerns in some quarters about maintaining public and congressional support in a program with years between flights and competing demands on agency funding.

- Lightfoot said there have been no discussions with the administration about near-term astronaut flights to Mars. Just getting EM-1 off the ground will be difficult enough. The Government Accountability Office concluded last summer that NASA will have spent some $23 billion through EM-1 developing the SLS rocket, the Orion capsule and ground infrastructure.

- Putting a crew aboard would have driven that cost even higher. "We needed additional funding, and we needed additional time," said Bill Gerstenmaier, NASA's director of space flight. "We knew both of those had to be there, because we had certain components that just were not there. We didn't have crew displays, we didn't have an active abort system, we didn't have an active life support system. So we knew those had to get added in."

- In its initial configuration, the SLS Block 1 rocket will be made up of two shuttle-heritage five-segment solid-fuel boosters provided by Orbital ATK and a huge Boeing-built first stage powered by four hydrogen-burning RS-25 space shuttle main engines provided by Aerojet Rocketdyne.

- The Block 1 version features an interim upper stage derived from Boeing's Delta 4 rocket powered by a single hydrogen-fueled Aerojet Rocketdyne RL-10B2 engine. That upper stage is not currently human rated.

- The NASA study concluded that while it would be possible to upgrade the Orion spacecraft to accommodate a crew for the EM-1 flight — equipping it with life support systems, crew displays, a validated launch abort system and other critical elements — it would have required an additional $600 million to $900 million in funding. - And there would be additional technical risk and likely delays to accelerate software development and to retrofit the EM-1 Orion capsule to support a two-person crew.

Table 5: NASA affirms existing plan for first mission of SLS, Orion 16) 17) 18)

• April 6, 2017: Curtiss-Wright's Defense Solutions division has successfully delivered eight of the nine data acquisition flight units that it is building for use on NASA's Orion spacecraft planned for use in EM-1 (Exploration Mission-1), Orion's second test flight in space. 19)

- For the Orion EM-1 flight, Curtiss-Wright supplies its MnACQ-2000 Miniature Network Data Acquisition System, a compact, stackable Fast Ethernet 100BASE-T-based networked encoding unit that processes and delivers packetized instrumentation data to designated network nodes. Each of the nine rugged COTS-based units built for Orion EM-1 includes a radiation tolerant power supply, system management overhead and the specific signal conditioning modules needed to address the number and type of measurements needed during flight.

- Two 12-Port Ethernet switches that tie the system together and route the data and video have also been delivered for the Orion EM-1 flight. Curtiss-Wright expects to deliver the ninth and final MnACQ-2000 by the end of June 2017.

• February 27, 2017: ESA's contribution to NASA's Orion spacecraft is the European Service Module, providing the spacecraft with its main power source and propulsion mechanism. Designed by Airbus Defence and Space and assembled by OHB Sweden, the Propulsion Qualification Model was shipped to the NASA's White Sands facility in January. 20)

- The model is now set up and awaiting extensive testing by NASA, ESA and Airbus. Its 21 engines, including the Shuttle OMS (Orbital Maneuvering System) engine, eight auxiliary thrusters and 12 smaller thrusters will undergo 'hot firing', in which all engines will be ignited.


Figure 23: The European propulsion system of the Orion spacecraft has been installed at NASA's White Sands Test Facility in New Mexico and is ready for testing (image credit: NASA)

• February 16, 2017: Airbus DS has signed a new contract with ESA (European Space Agency) for the construction of the second European service module (ESM) for NASA's Orion spacecraft. The contract is worth around € 200 million. The ESM is a key element of Orion, the next-generation spacecraft that will take astronauts beyond LEO (Low Earth Orbit) for the first time since the end of the Apollo program. 21)

• In mid-January 2017, Airbus Defence and Space delivered to NASA a propulsion test module for the Orion program. The PQM (Propulsion Qualification Test Model) will be used to check that the Orion ESM (European Service Module) spacecraft's propulsion subsystem functions correctly. On behalf of ESA, Airbus DS is the prime contractor for the ESM, a key element of NASA's next generation Orion spacecraft. 22)

- Although the PQM will never see space, this is an important step in the development of the Orion program. Complex systems for human spaceflight must first be tested and qualified on Earth before being used as flight hardware in space. The engineers want to determine how the system behaves in different environments, to ensure that it functions properly.

- The test module is travelling via Bremerhaven and Houston / USA to its final destination at NASA's WSTF (White Sands Test Facility) near Las Cruces in New Mexico / USA. Arrival is expected mid-February. The tests will take place later in the year at WSTF for the qualification of Orion ESM's propulsion subsystem.

• On December 12, 2016, ESA handed over ownership of the Orion European Service Module test article to NASA at the agency's Plum Brook facility in Sandusky, Ohio – marking the end of individual testing for the structure. 23)

- The module sits directly below Orion's crew capsule and provides propulsion, power, thermal control, and water and air for four astronauts. The solar array spans 19 m and provides enough electricity to power two households.

- From a design perspective, the launch is one of the most demanding moments in a mission. Orion will sit atop the SLS (Space Launch System) and more than 2500 tons of propellant. The vibrations and forces are intense until they reach the relative calm of space.

- To ensure the service module can withstand these forces, it is placed on a large table that shakes and moves to recreate the vibrations of launch. Almost 1000 sensors monitor how the 35 ton spacecraft flexes and withstands the stress. The blue wires carry the data during the tests for later analysis.

- The tests are running smoothly and the first flight model is already being built in Bremen, Germany. It will be shipped to the USA next year for more testing and final integration ahead of launch at the end of 2018.


Figure 24: This test article of the Orion ESM has the same structure and mass as the real thing but does not include the electronics and engines. It is being used to confirm the design before starting to build the flight version (image credit: ESA)

• January 2, 2017: A former space shuttle OMS-E (Orbital Maneuvering System-Engine) has been delivered to Germany for attachment to the European-built service module destined to steer NASA's next Orion spacecraft (EM-1) on a course around the moon on an uncrewed test flight in late 2018. 24)

- The engine was refurbished and reassembled at NASA's White Sands Test Facility in New Mexico, then shipped to Johnson Space Center in Houston for shake testing and returned to White Sands for leak tests, according to an ESA (European Space Agency) blog post. 25)

- It flew from Dallas/Fort Worth International Airport to Frankfurt last month, and then continued its journey by truck to Airbus Defense and Space's spacecraft assembly facility in Bremen, Germany, ESA said.

- ESA is providing the service modules for at least the next two Orion missions — an unpiloted shakedown cruise in lunar orbit scheduled to lift off in November 2018, and the first Orion flight with astronauts on-board in the early 2020s.

- European governments agreed to pay for the service module for the 2018 flight, named EM-1 (Exploration Mission-1), at a meeting of government ministers in December 2012. ESA member states last month committed funding for a second service module for EM-2 (Exploration Mission-2), which will carry up to four astronauts farther than the moon's orbit as soon as 2021.


Figure 25: Orion's service module engine, OMS-E, undergoes vibration testing at NASA/JSC (Johnson Space Center) in Houston (image credit: NASA)

- The service module has 33 engines and thrusters to control the Orion capsule's orientation and adjust its trajectory after launch. The main engine for EM-1 is a refurbished OMS-E (Orbital Maneuvering System-Engine) that flew on 19 space shuttle missions.

- The OMS engines were mounted on pods on each side of the shuttle's vertical tail, used to change the craft's orbit and begin the spaceship's trip back to Earth with a de-orbit burn.

- The ESM (European Service Module) has 33 engines and thrusters to control the Orion capsule's orientation and adjust its trajectory after launch. The main engine for EM-1 is a refurbished Orbital Maneuvering System engine that flew on 19 space shuttle missions (Figure 26).

- The OMS engines were mounted on pods on each side of the Shuttle's vertical tail, used to change the craft's orbit and begin the spaceship's trip back to Earth with a de-orbit burn. - The engines burn hydrazine and nitrogen tetroxide propellants, and were each designed for 100 missions and rated for multiple restarts on each flight. Aerojet Rocketdyne built the OMS engines, which provide around 26.6 kN of thrust in vacuum.

- The OMS engine slated to launch on EM-1 flew on the shuttle Challenger, Discovery and Atlantis in its career. Its first launch was on the STS-41G mission in October 1984, and its last shuttle mission was STS-112 in October 2002.


Figure 26: The Shuttle Atlantis touches down at KSC's Shuttle Landing Facility runway on Oct. 18, 2002. One of the OMS engines mounted on each side of the tail will fly on Orion's EM-1 mission beyond Earth orbit in late 2018 (image credit: NASA)

- The European-built service module is in the "critical path" for EM-1 to remain on track for its launch readiness window, which runs from September through November of 2018. The service module is due for delivery to NASA/KSC (Kennedy Space Center) in Florida in April 2017 — after engineers in Germany add the OMS engine and propellant tanks to the already-finished primary structure.

- At KSC, ground crews will connect the service module with the Orion crew module, then ship the spacecraft to NASA's Plum Brook Station in Ohio by the end of 2017 to subject it to the extreme temperatures and vacuum conditions it will encounter in space.

- The craft will return to KSC in early 2018 for final assembly steps, including the spacecraft's fueling and the addition of the Orion launch abort system before the stack is mounted on top of NASA's SLS (Space Launch System) inside the Vehicle Assembly Building for rollout to launch pad 39B.


Figure 27: Artist's rendition of the Orion spacecraft with the European-built service module (image credit: NASA)

• December 7, 2016: ESA and NASA are extending their collaboration in human space exploration following confirmation that Europe will supply a second Service Module to support the first crewed mission (EM-2)of the Orion spacecraft. The mission is set for launch from NASA's Kennedy Space Center in Florida, USA, as early as 2021 and will include up to four astronauts – the first time humans have left low orbit since 1972. Crew size and composition will be determined closer to launch. 26)

• Nov. 21, 2016: The processing activity at NASA/KSC (Kennedy Space Center) in Florida has ramped up in preparation for the agency's launch of the Orion spacecraft atop the SLS (Space Launch System) rocket on its first deep space mission, Exploration Mission 1 (EM-1). The Orion CMA (Crew Module Adapter) for EM-1 was lifted for the first and only time, Nov. 11, during its processing flow inside the Neil Armstrong Operations and Checkout (O&C) Building high bay at KSC. 27)

- The CMA will connect the Orion crew module to the European Space Agency-provided service module. The Orion spacecraft will launch on the SLS rocket on EM-1 scheduled for late 2018.


Figure 28: Image of the CMA uplift on Nov. 11. The CMA is now undergoing secondary structure outfitting (image credit: NASA, Glen Benson)

• Sept. 19, 2016: The Orion heat shield that will protect the Orion crew module during re-entry after the spacecraft's first uncrewed flight atop NASA's Space Launch System rocket in 2018 arrived at the agency's Kennedy Space Center in Florida on on August 25. It was transported to the Shuttle Landing Facility, which is managed and operated by Space Florida, aboard NASA's Super Guppy aircraft. 28)

- The shipping container with the heat shield inside was offloaded and transported to the Neil Armstrong Operations and Checkout (O&C) Building high bay where technicians uncrated and secured it on a stand to begin the work to prepare it for Orion's next test flight, known as EM-1 (Exploration Mission-1).

- The heat shield was designed and manufactured by Lockheed Martin in the company's facility near Denver. Orion's heat shield will be capable of withstanding temperatures of up to 2750ºC during reentry into Earth atmosphere. The heat shield measures 5 m in diameter, making it the largest of its kind.


Figure 29: Inside the Neil Armstrong Operations and Checkout Building high bay at NASA's Kennedy Space Center in Florida, technicians assist as a crane lifts the Orion heat shield for EM-1 away from the base of its shipping container (image credit: NASA, Dimitri Gerondidakis)

• June 27, 2016: NASA and ESA conducted a CDR (Critical Design Review) culminating in a final review board June 16 for Orion's European-built service module (Figure 30). The service module is an essential part of the spacecraft that will power, propel, and cool Orion in deep space as well as provide air and water for crew members. The CDR rounds out the latest in a series of reviews for the three human exploration systems development programs that will enable the journey to Mars. 29)

- The recently completed review focused on the overall service module design while discussing differences between Orion's first deep space mission atop the SLS (Space Launch System) rocket and the mission to follow that will carry crew. No new major issues were identified during the review, and the teams worked together to develop a plan for work going forward in areas such as power, solar array management and propellant usage.

- "The teams at NASA and ESA worked together successfully over the past few weeks to bring design decisions and required products to the CDR board," said William Gerstenmaier, associate administrator for NASA's Human Exploration and Operations Mission Directorate. "International collaboration is an important part of the effort NASA is leading to pioneer deep space."

- The review was conducted at ESA/ESTEC (European Space Research and Technology Center) in Noordwijk, the Netherlands with teams from NASA, ESA, Lockheed Martin and Airbus Defence & Space in Bremen, Germany. Lockheed Martin is NASA's main contractor building Orion, and Airbus is ESA's contractor for the service module.

- The CDR identified April 2017 as the target for the service module delivery to Kennedy Space Center in Florida. Teams will begin integrating hardware into the rocket before the service module is delivered, and NASA plans to continue to optimize processing when it arrives at Kennedy. Initial results maintain EM-1 launch date no later than November 2018.

• May 25, 2016: Replicating the thunderous noise of a rocket launch is no easy task, but engineers at NASA Glenn's Plum Brook Station in Sandusky, Ohio are mimicking the launch environment the Orion spacecraft will experience on a 2018 mission beyond the moon. They recently concluded a series of tests on a structural representation of the Orion service module to help ensure it can withstand the force and pressure of the acoustics environment it will experience as it makes its way from the launch pad to space atop NASA's Space Launch System rocket. 30)

- Orion's service module is a critical piece of the overall spacecraft. Provided by ESA (European Space Agency) and built by Airbus Defence & Space, the 13 ton component will be responsible for propelling, powering and cooling the vehicle, as well as providing air and water for its eventual crew.

- When a powerful rocket launches, it can produce noise of up to 180 decibels, levels so high that it can vibrate and damage spacecraft components if they aren't designed and built to be strong enough to withstand the environment. For comparison, a person standing about 100 m away from a jet taking off would experience approximately 130 decibels of sound pressure, and for every additional 10 decibels, sound intensity increases 10-fold.

- While engineers have designed Orion components to endure a range of harsh environments like launch and missions in space, testing on the ground helps to validate computer modeling predictions. "Orion is undertaking an unprecedented mission, so the acoustics testing we've done is helping us make sure the service module will fare as we expect it to," said Aron Hozman, lead engineer for the acoustics testing campaign.

- Engineers performed numerous evaluations at different decibel levels over the course of several weeks in Plum Brook Station's Reverberant Acoustic Test Facility. The facility is the world's most powerful spacecraft acoustic test chamber. In it, a series of modulators or horns embedded on one of the facility's walls and supporting subsystems such as a gaseous nitrogen generation system and a hydraulic supply system were used to modulate noise and produce a wide range of acoustic spectra.

- The series of testing was done in two configurations – one with "wet" tanks where the service module's propellant tanks were filled with a simulant that modeled the density of Orion fuel, and with them empty to determine if the noise affected the structure differently. The maximum test with fuel simulant lasted approximately three minutes. Engineers also used the testing to help qualify the service module's solar array wing. They placed a microphone inside the test article and determined that the noise in the test chamber matched the expected acoustic environment inside the service module where the wing is housed.

- The service module structural test article will next move to Plum Brook Station's Mechanical Vibration Facility, a powerful spacecraft shaker system that will help assess the component's ability to withstand the tremor that an SLS launch will produce. As these ground tests continue to validate the service module's design, the first flight unit service module for EM-1 is now being built in Europe. This unit, which will be built by the same teams who built the structural test article, recently arrived to Airbus' facility in Bremen, Germany for integration. It is expected to be shipped to the United States in 2017.

• May 19, 2016: Airbus DS has started assembling the ESM (European Service Module), a key element of NASA's next-generation Orion spacecraft that will transport astronauts into deep space for the first time since the end of the Apollo program. Integrating more than 20,000 parts and components in the ESM flight model ranging from electrical equipment to rocket engines, solar arrays, tanks for propellant and life support consumables as well as hundreds of meters of cables and tubes marks a major milestone for the Orion program. After the arrival of the flight model structure from Thales Alenia Space Italy the assembly is being carried out at Airbus Defence and Space's site at Bremen, Germany, where officials from ESA, NASA, Airbus Defence and Space and partners gave an update on the Orion program's progress on May 19. 31)

- The ESM is cylindrical in shape and about four meters in diameter and in height. It features the ATV's (Automated Transfer Vehicle) distinctive four-wing solar array (19 m across unfurled) that generates enough electricity to power two households. Its 8.6 tons of propellant will power one main engine and 32 smaller thrusters. The ESM has a total mass of just over 13 tons. In addition to the main propulsion capability for the Orion spacecraft, the ESM will perform orbital maneuvering and attitude control functions. It also provides the main elements of the life support system such as water and oxygen for the crew while providing power and thermal control while it is docked to the crew module. The unpressurized service module can also be used to carry additional cargo.

• May 11, 2016: The EM-1 has passed a critical series of proof pressure tests which confirm the effectiveness of the welds holding the spacecraft structure together. Lockheed Martin, the manufacturer of the Orion crew module, ran the test at incremental steps over two days to reach the maximum pressure. During each step, the team pressurized the chamber and then evaluated the data to identify changes for the next test parameter. The results revealed the workmanship of the crew module pressure vessel welds and how the welds reacted to the stresses from the pressurization. 32)

• April 29, 2016: The first European hardware to arrive at NASA for Orion is the ESM (European Service Module) structural test article. This test version of the service module has the same mass and configuration as the real thing and will undergo advanced testing at NASA's Plum Brook Station in Ohio, USA. 33)


Figure 30: Photo of the European Structural Test Article which undergoes testing in NASA's acoustic test facility in Plum Brook, Ohio, USA (image credit: NASA)

• On 29 February 2016, a test model of Orion's solar array was unfolded at NASA's Plum Brook Station test facility in Sandusky, Ohio to check everything works as expected. The solar panels were made by Airbus Defence and Space in the Netherlands for the ESA module that will supply power and life support for up to four astronauts. 34)

- Each wing stretches more than 7 m, folded inside the SLS (Space Launch System's) rocket of NASA that will launch the spacecraft on its first unmanned mission in 2018. Orion sports four wings of three panels with 1242 cells per panel to provide 11.1 kW of power – enough to run two typical European households. The distinctive X-wings are an evolution and improvement of ESA's ATV (Automated Transfer Vehicle).

- The test was passed with flying colors as the 260 kg array unfurled into its flight configuration. The stresses of flying to the Moon and beyond – and back again – mean the array is designed to bend up to 60º forward and backward, much like a bird in flight.


Figure 31: Photo of the Orion wing array unfolding test at NASA's Plum Brook Station (image credit: ESA)

• Feb. 2. 2016: NASA's unique Super Guppy aircraft, loaded with the structural backbone for NASA's next Orion crew module, swooped in for a landing at the KSC (Kennedy Space Center) on Feb. 1, 2016 (coming from NASA's Michoud Assembly Facility in New Orleans). Orion's arrival at KSC marks a major milestone on the road to starting NASA's 'Journey to Mars' initiative. 35)

- This Lunar Orion vehicle is destined for blastoff to the Moon in 2018 on NASA's EM-1 (Exploration Mission-1) atop the agency's mammoth SLS (Space Launch System) rocket. EM-1 is a 'proving ground' mission that will fly an unmanned Orion thousands of kilometers beyond the Moon, further than any human capable vehicle, and back to Earth, over the course of a three-week mission.


Figure 32: The nose of the Super Guppy aircraft opened to reveal cargo hold carrying the Orion crew module pressure vessel after arrival at KSC (image credit: Ken Kremer)

• January 22, 2016: The first European hardware to arrive at NASA for Orion is the European Service Module structural test article (Figure 33). This test version of the service module has the same weight and configuration as the real thing and will undergo advanced testing at NASA's Plum Brook Station in Ohio, USA. Once mating is complete the Service Module will have a mass of 13,000 kg in total. The Service Module will be placed on a shaker and vibrated to recreate the stress of launch. 36)


Figure 33: In this picture, the European Service Module structural test article is being 'mated' to the Crew Module Adapter, which connects the service module to the Orion Crew Module (image credit: ESA, NASA)

• January 2016: In a major step towards flight, engineers at NASA's Michoud Assembly Facility in New Orleans have finished welding together the pressure vessel for the first Lunar Orion crew module that will blastoff in 2018 atop the agency's SLS (Space Launch System) rocket. The 2018 launch of NASA's Orion on an unpiloted flight dubbed Exploration Mission, or EM-1, counts as the first joint flight of SLS and Orion, and the first flight of a human rated spacecraft to deep space since the Apollo Moon landing era ended more than 4 decades ago. 37)

- The friction-stir welding work to assemble the primary structure of NASA's maiden Lunar Orion capsule was just finished last week on Jan. 13. According to NASA, friction-stir welding produces incredibly strong bonds by transforming metals from a solid into a plastic-like state, and then using a rotating pin tool to soften, stir and forge a bond between two metal components to form a uniform welded joint, a vital requirement of next-generation space hardware.


Figure 34: Orion EM-1 pressure vessel was completed Jan. 13, 2016 at NASA's Michoud Assembly Facility in New Orleans, LA. The pressure vessel is the spacecraft's underlying structure on which all of the spacecraft's systems and subsystems are built and integrated (image credit: NASA)

• Nov. 16, 2015: After the completion of Orion's CDR (Critical Design Review) in October, the spacecraft is one important step closer toward the upcoming EM-1 (Exploration Mission-1, scheduled to take place in 2018. It means that Lockheed Martin, the prime contractor building Orion, can now focus on full-scale fabrication, assembly, integration and tests of the spacecraft. 38)

• Nov. 10, 2015: A test version of ESA's service module for NASA's Orion spacecraft arrived at the Cleveland Hopkins airport in Ohio, USA before continuing by road to NASA's Plum Brook Station. 39) 40) 41)

- The module sits directly below Orion's crew capsule and provides propulsion, power, thermal control, and water and air for four astronauts. The solar array spans 19 m and provides enough to power two households. A little over 5 m in diameter and 4 m high, it weighs 13.5 tons. The 8.6 tons of propellant will power one main engine and 32 smaller thrusters.

- Following initial tests in Europe, it will now undergo rigorous vibration tests in NASA's Plum Brook Station in Ohio to ensure the structure and components can withstand the extreme stresses during launch.

• Nov. 6, 2015: Airbus Defence and Spa0ce is preparing to deliver the Orion ESM (European Service Module) structural test model to NASA. The model is an exact copy of the flight model, only without the functionality. It will determine whether the structural and weight specifications have been met, and whether the module lives up to NASA's crew safety requirements. Testing will take place at NASA's Plum Brook Station test center in Ohio, USA. 42)

- The design of the ESM is based on the ATV (Automated Transfer Vehicle), the European supply craft for the International Space Station. It is a cylindrical module with a diameter of 4.5 m and a total length – main engine excluded – of 2.7 m. It is fitted with four solar array 'wings' with a span of 18.8 m. Besides propulsion and power, the ESM is also equipped with oxygen tanks to supply the crew.


Figure 35: A look at the propulsion side of the Orion ESM (European Service Module) structural test model (image credit: Airbus Defence and Space SAS 2015)

• Oct. 26, 2015: Lockheed Martin and NASA have completed the majority of Orion's CDR (Critical Design Review) which means the spacecraft's design is mature enough to move into full-scale fabrication, assembly, integration and test of the vehicle. It also means that the program is on track to complete the spacecraft's development to meet NASA's Exploration Mission-1 (EM-1) performance requirements. The complete Orion EM-1 CDR process will conclude after the European Service Module CDR and a presentation to the NASA Agency Program Management Council in the spring 2016. 43) 44)

- Orion's CDR kicked off in August 2015. The review focused on the EM-1 design as well as additional common elements that will be included on the Exploration Mission-2 (EM-2) spacecraft. These elements include the structure, pyrotechnics, LAS (Launch Abort System), software, guidance, navigation and control, and many others.

- Although the EM-1 vehicle is designed to accommodate all the necessary elements for human exploration of deep space, systems unique to the EM-2 mission, such as crew displays and the Environmental Control and Life Support System, will be evaluated at a later EM-2 CDR.

- In early 2016, Orion's crew module pressure vessel will be shipped to the Operations and Checkout Facility at NASA's Kennedy Space Center. There it will undergo final assembly, integration and testing in order to prepare for EM-1 when Orion is launched atop NASA's SLS (Space Launch System) for the first time.

• Oct. 22, 2015: NASA completes the CDR (Critical design Review) for SLS (Space Launch System). The CDR examined the first of three configurations planned for the rocket, referred to as SLS Block 1. The Block I configuration will have a minimum 70-metric-ton (77-ton) lift capability and be powered by twin boosters and four RS-25 engines. The next planned upgrade of SLS, Block 1B, would use a more powerful exploration upper stage for more ambitious missions with a 105-metric-ton (115-ton) lift capacity. Block 2 will add a pair of advanced solid or liquid propellant boosters to provide a 130-metric-ton (143-ton) lift capacity. In each configuration, SLS will continue to use the same core stage and four RS-25 engines. 45)

• Oct. 12, 2015: Aerojet Rocketdyne announced that it passed the CDR (Critical Design Review) for the jettison motor and the crew module RCS (Reaction Control System) on the Orion spacecraft. These two major subsystems that Aerojet Rocketdyne is building for Lockheed Martin and NASA are critical for ensuring astronaut safety and mission success. Astronaut safety is paramount and the jettison motor and the crew module reaction control system will ensure that the crew begins their mission into deep space and lands at the completion without harm. 46)

- The jettison motor is a solid rocket motor that separates the launch abort system from the Orion spacecraft about five seconds after fairing separation, allowing the crew to continue safely on their way into deep space. In addition to its normal operations, the jettison motor serves a double duty if an anomaly occurs. Designed to assist crew escape, the jettison motor is one of three solid rocket motors on the launch abort system that will rapidly pull the capsule away from the stack in the event of an emergency.

- The RCS on the crew module the company is providing for Orion is equally important to crew safety. The crew module RCS provides the only course control authority after separation from the service module. It ensures that the heat shield is properly oriented, the crew module is stable under the parachutes and that the vehicle is in the correct orientation for splashdown.

• NASA is a small step closer to sending astronauts on a journey to Mars. On Sept. 5, 2015, engineers at the agency's MAF (Michoud Assembly Facility) in New Orleans welded together the first two segments of the Orion crew module that will fly atop NASA's SLS (Space Launch System) rocket on a mission beyond the far side of the moon. 47)


Figure 36: At NASA's MAF in New Orleans, engineers welded together on Sept. 5, 2015 two sections of the Orion spacecraft's primary structure that will fly on Exploration Mission-1, the first flight of Orion atop the agency's Space Launch System rocket (image credit: NASA)

The primary structure of Orion's crew module is made of seven large aluminum pieces that must be welded together in detailed fashion (Figure 37). The first weld connects the tunnel to the forward bulkhead, which is at the top of the spacecraft and houses many of Orion's critical systems, such as the parachutes that deploy during reentry. Orion's tunnel, with a docking hatch, will allow crews to move between the crew module and other spacecraft.

"Each of Orion's systems and subsystems is assembled or integrated onto the primary structure, so starting to weld the underlying elements together is a critical first manufacturing step," said Mark Geyer, Orion Program manager. "The team has done tremendous work to get to this point and to ensure we have a sound building block for the rest of Orion's systems."

Engineers have undertaken a meticulous process to prepare for welding. They have cleaned the segments, coated them with a protective chemical and primed them. They then outfitted each element with strain gages and wiring to monitor the metal during the fabrication process. Prior to beginning work on the pieces destined for space, technicians practiced their process, refined their techniques and ensured proper tooling configurations by welding together a pathfinder, a full-scale version of the current spacecraft design.

NASA's prime contractor for the spacecraft, Lockheed Martin, is doing the production of the crew module at Michoud.

Through collaborations across design and manufacturing, the teams have been able to reduce the number of welds for the crew module by more than half since the first test version of Orion's primary structure was constructed and flown on the EFT-1 (Exploration Flight Test-1) in December 2014. The EM-1 (Exploration Mission-1) structure will include just seven main welds, plus several smaller welds for start and stop holes left by welding tools. Fewer welds will result in a lighter spacecraft.



Figure 37: Seven welds of Orion's pressure vessel. This diagram shows the seven pieces of Orion's primary structure and the order in which they are welded together (image credit: NASA)

The tunnel is the passageway astronauts crawl in and out of when Orion is docked with another vehicle. The forward bulkhead, located at the top of the crew module, must handle extreme loads during re-entry because that is where the parachutes are connected when they deploy. In order to certify the new welding process, the team at Michoud Assembly Facility welded a pathfinder vehicle to verify the design changes and welding changes would perform as expected. 48)

In early 2016, once the pieces that make up the crew module's pressure vessel are welded together, it will be shipped to the Operations and Checkout Facility at NASA's Kennedy Space Center. There it will undergo final assembly, integration and testing in order to prepare for Exploration Mission-1 when Orion is launched atop NASA's SLS (Space Launch System) for the first time. The test flight will send Orion into lunar distant retrograde orbit—a wide orbit around the moon that is farther from Earth than any human-rated spacecraft has ever traveled. The mission will last more than 20 days and will certify the design and safety of Orion and SLS for human-rated exploration missions.


Launch: Orion EM-1 will launch uncrewed on the maiden test flight of NASA's SLS (Space Launch System). Liftoff is targeted for 'no earlier than' Dec. 15, 2019 and SLS will be configured in its initial 70 metric ton version. The SLS-1/EM-1 test flight with the uncrewed Orin spacecraft will launch from Launch Complex 39-B at the Kennedy Space Center, Cape Canaveral, FL (Ref. 52). 49)

The EM-1 mission will last more than three weeks, sending the Orion spacecraft into a high-altitude retrograde orbit around the moon before heading back to Earth for a splashdown in the Pacific Ocean.



SLS (Space Launch System):

The SLS is the new heavy launch system for NASA. The SLS configuration for EM-1 is considered Block 1, the first configuration of the SLS evolution plan. The Shuttle-derived design takes advantage of resources established for the Space Shuttle, including the workforce, tooling, manufacturing processes, supply chain, transportation logistics, launch infrastructure, and LOX/LH2 propellant infrastructure. An overview of the initial SLS Block 1 configuration that will first fly with the Orion in 2018 is shown in Figure 38. The SLS enables many aspects of the NASA core capabilities in addition to human exploration initiatives. These include the reduction in mission duration, increased mass margins, reductions in total spacecraft complexity, and significant increases in payload volume (Ref. 53).

The secondary payload initiative for EM-1 takes advantage of several of these capabilities and enables new opportunities for small spacecraft developers. By utilizing planned unoccupied volume within the upper stage adapter ring, the OSA (Orion Stage Adapter), increased mission science and technology missions can be accommodated.

SLS Block 1 is capable of deploying 70 metric tons of payload into LEO (Low Earth Orbit). The characteristic energy (C3) curve for SLS is provided in Figure 2, illustrating SLS's evolved thrust capabilities.


Figure 38: SLS Block 1 70t Initial Configuration (image credit: NASA)


Figure 39: Welding is complete on the largest piece of the core stage that will provide the fuel for the first flight of NASA's new rocket, the Space Launch System, with the Orion spacecraft in 2018. The core stage liquid hydrogen tank has completed welding on the Vertical Assembly Center at NASA's Michoud Assembly Facility in New Orleans. Standing more than 40 m tall and 8.4 m in diameter, the liquid hydrogen tank is the largest cryogenic fuel tank for a rocket in the world. The liquid hydrogen tank and liquid oxygen tank are part of the core stage — the "backbone" of the SLS rocket that will stand at more than 61 m tall. Together, the tanks will hold 733,000 gallons (2775 m3) of propellant and feed the vehicle's four RS-25 engines to produce a total of 2 million pounds of thrust (8896 kN) This is the second major piece of core stage flight hardware to finish full welding on the Vertical Assembly Center. The core stage flight engine section completed welding in April 2016. More than 1.7 miles of welds have been completed for core stage hardware at Michoud. Traveling to deep space requires a large rocket that can carry huge payloads, and SLS will have the payload capacity needed to carry crew and cargo for future exploration missions, including NASA's Journey to Mars. 50)


Figure 40: David Osborne, an Aerie Aerospace LLC machinist at NASA's Marshall Space Flight Center in Huntsville, Alabama, takes measurements prior to the start of precision machining of the Orion stage adapter for NASA's new rocket, the SLS (Space Launch System). The adapter will connect the Orion spacecraft to the ICPS (Interim Cryogenic Propulsion Stage) for the first flight of SLS with Orion in late 2018. The ICPS is the liquid oxygen/liquid hydrogen-based system that will give Orion the big, in-space push needed to fly beyond the moon before it returns to Earth. The adapter also will carry 13 CubeSats that will perform science and technology investigations that will help pave the way for future human exploration in deep space, including the Journey to Mars (image credit: NASA, Sept. 29, 2016)


Figure 41: SLS Net-Payload System Mass-Earth Escape (image credit: NASA)


SLS development status:

• October 19, 2017: NASA engineers conducted a full-duration, 500-second test of RS-25 flight engine E2063 on the A-1 Test Stand at SSC (Stennis Space Center) on Oct. 19, 2017. Once certified, the engine is scheduled to help power NASA's new Space Launch System rocket on its EM-2 (Exploration Mission-2). The test was part of Founders Day Open House activities at Stennis. 51)

- Engine E2063 is scheduled for use on NASA's second mission of SLS and Orion, known as EM-2. The first integrated flight test of SLS and Orion, EM-1 (Exploration Mission-1), will be an uncrewed final test of the rocket and its systems. The EM-2 flight will be the first to carry astronauts aboard the Orion spacecraft, marking the return of humans to deep space for the first time in more than 40 years.

• September 22, 2017: Following a series of issues over the last year with the Core Stage for the first flight of the Space Launch System rocket, the launch dates for both the EM-1 and EM-2 flights are beginning to align, with EM-1 now targeting 'No Earlier Than' 15 December 2019 and EM-2 following on 1 June 2022. Additionally, the EM-3 flight has gained its first notional mission outline, detailing a flight to Near-Rectilinear Halo Orbit to deploy the Hab (Habitat) module for the new Deep Space Gateway. 52)

- The first flight of any new rocket is bound to encounter design and initial production delays. And NASA's SLS (Space Launch System ) rocket is been no stranger to those sort of anticipated effects. - Following a misalignment in the installation of the main welding machine at the Michoud Assembly Facility (MAF), welding for the certification elements for the new SLS core stage Liquid Hydrogen (LH2) and Liquid Oxygen (LOX) tanks picked up.

- After the initial LH2 qualification tanks were welded, a change to the welding machine's pin was made – a change that resulted in segment welds on the EM-1 LH2 flight tank being too brittle to meet flight specification requirements.

- This pin change and subsequent issue led to the understanding that the LH2 flight tank for EM-1 was no longer flight worthy and thus could not be used for EM-1.

- A plan was then put in place to restore the welding machine's previously used pin – the one that welded all the Core Stage test articles that have thus far passed all qualification and acceptance testing – and use the upcoming weld for the EM-2 flight LH2 tank as the new LH2 tank for the EM-1 flight.

- However, less than a week after the EM-1 LH2 flight tank issue became known, a worker at MAF damaged the aft dome section of the qualification article for the Core Stage LOX tank.

- In all, these production issues quickly made the Core Stage's timeline for EM-1's then-2018 launch date impossible.

- Earlier this year, NASA acknowledged this and announced that EM-1 was slipping to sometime in 2019 – though that was already understood to be "Q4 2019."



Payload Accommodations on EM-1:

Secondary payloads on EM-1 will be launched in the OSA (Orion Stage Adapter). Payload dispensers will be mounted on specially designed brackets, each attached to the interior wall of the OSA as shown in Figure 42. For the EM-1 mission, a total of fourteen brackets will be installed, allowing for thirteen payload locations. The final location will be used for mounting an avionics unit, which will include a battery and sequencer for executing the mission deployment sequence. 53)


Figure 42: The Orion Stage Adapter with payload locations (image credit: NASA)

Each bracket is designed to hold the volume equivalent of 6U and 12U dispensers. The current design baseline for the EM-1mission is for payloads to be compatible with 6U class dispensers. Payloads in 6U class will be limited to 14 kg maximum mass. Detailed physical accommodations are documented in Table 6 and Figure 43.

The avionics unit will interface with each deployer through cables mounted in the OSA. Payloads will remain powered off until the sequencer transmits the deployment signal to each dispenser, and the payload is released. Payloads will exit the dispenser at an approximate rate of 1.2 m/s, with deployments separated by a minimum of 5 seconds. No other payload services are currently planned for EM-1.





6U configuration

239.4 mm

366 mm

116 mm

12 U configuration

239.4 mm

366 mm

229 mm

Table 6: Payload maximum dimensions


Figure 43: Payload volume dimension (image credit: NASA)


GSDO (Ground Systems Development and Operations) : The GSDO program at the KSC (Kennedy Space Center) will perform SLS ground processing. Payloads will be fully integrated into their dispenser at the time of delivery to GSDO. Once delivered, integrated payloads will be installed into the OSA, prior to stacking operations with the Orion system. Prior to roll-out to the pad, battery charging for the avionics unit and each payload containing approved batteries will occur at the VAB (Vehicle Assembly Building).


Operations: Secondary payloads on SLS will remain powered off during the ascent phase of the launch vehicle, through separation of the Orion spacecraft. Once separation is confirmed, the ICPS will send a discrete signal to the SPDS avionics to activate. The schedule for deployments will be loaded as a skit prior to vehicle stacking. No real-time commanding or telemetry is available; therefore payloads will be deployed automatically through the pre-determined mission timeline sequence.

Payloads will have opportunity to deploy beginning after the ICPS disposal sequence is complete (approximately T+4 hours) up to 10 days from launch. All deployments will be completed before avionics batteries are expended. Figure 44 provides an overview of the mission profile.

Once deployed, payloads will be required to wait 15 seconds before deploying antennas, solar panels, sails, etc. to ensure adequate clearance from ICPS. Payload communications following deployment will be the responsibility of the payload project, with no resources being provided by SLS.


Figure 44: EM-1 mission profile (NASA)



Secondary payloads of Orion/EM-1

The first flight of NASA's new rocket, SLS ( Space Launch System), will carry 13 CubeSats/Nanosatellites to test innovative ideas along with an uncrewed Orion spacecraft in 2019. These small satellite secondary payloads will carry science and technology investigations to help pave the way for future human exploration in deep space, including the journey to Mars. SLS' first flight, referred to as EM-1 (Exploration Mission-1 ), provides the rare opportunity for these small experiments to reach deep space destinations, as most launch opportunities for CubeSats are limited to low-Earth orbit. 54)

The secondary payloads, 13 CubeSats, were selected through a series of announcements of flight opportunities, a NASA challenge and negotiations with NASA's international partners.

NASA selected two payloads through the NextSTEP (Next Space Technologies for Exploration Partnerships) Broad Agency Announcement of May 5, 2015:

Skyfire - Lockheed Martin Space Systems Company, Denver, Colorado, will develop a 6U CubeSat to perform a lunar flyby of the moon, taking sensor data during the flyby to enhance our knowledge of the lunar surface

Lunar IceCube - Morehead State University, Kentucky, will build a 6U CubeSat to search for water ice and other resources at a low orbit of only 100 km above the surface of the moon

Three payloads were selected by NASA's Human Exploration and Operations Mission Directorate:

NEA Scout (Near-Earth Asteroid Scout), the 6U CubeSat of NASA/MSFC/JPL will perform reconnaissance of an asteroid, take pictures and observe its position in space

BioSentinel - a 6U CubeSat of NASA/ARC will use yeast to detect, measure and compare the impact of deep space radiation on living organisms over long durations in deep space

Lunar Flashlight - a 6U CubeSat of NASA/JPL/MSFC will look for ice deposits and identify locations where resources may be extracted from the lunar surface

Two payloads were selected by NASA's Science Mission Directorate:

CuSP – a 6U CubeSat of the SwRI (Southwest Research Institute) "space weather station" to measure particles and magnetic fields in space, testing the practicality for a network of stations to monitor space weather

LunaH-Map a 6U CubeSat of Arizona State University will map hydrogen within craters and other permanently shadowed regions throughout the moon's south pole

Three additional payloads will be determined through NASA's Cube Quest Challenge – sponsored by NASA's Space Technology Mission Directorate and designed to foster innovations in small spacecraft propulsion and communications techniques. CubeSat builders will vie for a launch opportunity on SLS' first flight through a competition that has four rounds, referred to as ground tournaments, leading to the selection in 2017 of the payloads to fly on the mission.

Finally, three slots reserved for international partners will be occupied by JAXA (with 2 cubesats) and ASI. It is understood that kind of opportunity should arise again on subsequent SLS flights.

Table 7: Overview of selected secondary missions for the inaugural Orion/EM-1 test flight

All the CubeSats will ride to space inside the Orion Stage Adapter, which sits between the ICPS ( Interim Cryogenic Propulsion Stage) and Orion. The CubeSats will be deployed following Orion separation from the upper stage and once Orion is a safe distance away.


CubeSats provided by international partners:

"The first SLS launch presents a great opportunity to collaborate with our international partners by providing rides for CubeSats that can pursue independent science and technology missions while supporting our mutual goals for human exploration in deep space," said Steve Creech, acting manager of the Spacecraft and Payload Integration and Evolution Office, which handles integration of the secondary payloads at NASA/MSFC (Marshall Space Flight Center) in Huntsville, Alabama, where SLS is managed. 55)

These small satellites are designed to be efficient and versatile—at no heavier than 14 kg, they are each about the size of a boot box, and do not require any extra power from the rocket to function. The science and technology experiments enabled by these small satellites may enhance our understanding of the deep space environment, expand our knowledge of the moon, and demonstrate technology that could open up possibilities for future missions. 56)

For EM-1, the first SLS flight, JAXA (Japan Aerospace Exploration Agency) and the University of Tokyo will jointly create and provide two CubeSats (nanosatellites).



Figure 45: Secondary payloads infographic (image credit: NASA) 57)

The secondary payloads will be described in separate files on the eoPortal — if sufficient technical information is available of each secondary mission.


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The information compiled and edited in this article was provided by Herbert J. Kramer from his documentation of: "Observation of the Earth and Its Environment: Survey of Missions and Sensors" (Springer Verlag) as well as many other sources after the publication of the 4th edition in 2002. - Comments and corrections to this article are always welcome for further updates (

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