JPSS-1 (Joint Polar Satellite System-1) / NOAA-20
JPSS is the next generation polar-orbiting operational environmental satellite system series of the USA, procured by NOAA (National Oceanic and Atmospheric Administration) through NASA, with the following major objectives: 1) 2) 3) 4) 5) 6)
• Increase timeliness and accuracy of severe weather event forecasts
• Provide advanced atmospheric temperature, moisture and pressure profiles from space
• Provide advanced imaging capability to analyze fires, volcanoes, Gulf oil tracking and other adverse incidents
• Direct broadcast data to field terminals at hour scale latency
• Maintain continuity of climate observations and critical environmental data from the polar orbit.
1) JPSS consists of three satellites (Suomi-NPP, JPSS-1, JPSS-2), ground system and operations through 2025
- The JPSS mission is to provide global imagery and atmospheric measurements using polar-orbiting satellites
2) JPSS is a partnership between NOAA and NASA
- NOAA has final decision authority and is responsible for overall program commitment
- JPSS Program is the subset of JPSS managed by NASA
- NASA is the acquisition agent for the flight system (satellite, instruments and launch vehicle), ground system, leads program systems engineering, and program safety and mission assurance
- NOAA is responsible for operations, data exploitation and archiving, infrastructure.
3) The partnership is governed by the NOAA and NASA JPSS Management Control Plan
- The JPSS Program is executed in accordance with NPR 7120.5D (NASA Procedural Requirements) as a loosely-coupled program
4) NASA Categorization for JPSS-1 and JPSS-2
- Mission Category 1
- Risk Class B Mission
- Category 2 Expendable Launch Vehicle
JPSS represents significant technological and scientific advances in environmental monitoring and will help advance environmental, weather, climate, and oceanographic science. JPSS's primary user, NOAA's NWS (National Weather Service), will use the JPSS data in models for medium- and long-term weather forecasting. JPSS will allow scientists and forecasters to monitor and predict weather patterns with increased speed and accuracy and is the key for continuity of long-standing climate measurements, allowing the study of long-term climate trends. JPSS will improve and extend climate measurements for 30 different EDRs (Environmental Data Records) of the atmosphere, land, ocean, climate and space environment. 7)
Since the 1960's the United States has operated two separate polar-orbiting environmental satellite programs:
- NOAA's POES (Polar-orbiting Operational Environmental Satellite) series
- USAF's DMSP (Defense Metrological Satellite Program) series.
• In 1994, the NPOESS (National Polar-orbiting Environmental Satellite System) program was created (under a Presidential Decision Directive) with the expectation that combining the civil (POES) and military (DMSP) programs would reduce duplication and result in cost savings
• A tri-agency IPO (Integrated Program Office) was formed to manage the program
- NOAA was responsible for overall program management of the converged system and satellite operations
- USAF (United States Air Force) was responsible for acquisition
- NASA responsible for technology insertion.
• Program was to launch NPP (NPOESS Preparatory Project) to reduce risk
• The first NPOESS contract awarded in 2002
- Program estimated to cost $7 billion through 2018
- Scope of program included six satellites (three orbits) each hosting up to 13 instruments, and a ground system.
• NPOESS program encountered significant challenges
- Technical challenges in VIIRS sensor development
- Program cost growth
- Schedule delays
• By 2005, the cost had increased to $10 billion and the first launch had to be delayed from 2008 to 2010
• A decision to restructure the program was made in 2006
- Driven by a Nunn-McCurdy breach
- Satellites reduced from six to four (in two orbits) – EUMETSAT would provide mid-morning orbit
- Number of instruments reduced from 13 to nine
• Even after restructure, program continued to encounter issues
- Technical issues continued with VIIRS
- Management challenges with governance structure
- Cost increases – expected to exceed $14 billion
- Further schedule delays. The major challenge of NPOESS was jointly executing the program between three agencies of different size with divergent objectives and different acquisition procedures.
• In 2009, EOP/OSTP (Executive Office of the President/Office of Science and Technology Policy) led a task force to investigate management and acquisition options that would improve NPOESS. An IRT (Independent Review Team) concluded that the current NPOESS program, in the absence of managerial and funding adjustments, has a low probability of success and data continuity is at extreme risk. The Office of Science and Technology, with the Office of Management and Budget and the National Security Council, as well as representatives from each agency, examined various options to increase the probability of success and reduce the risk to data continuity.
• In February 2010, with the release of the FY2011 President's Budget, OSTP announced the restructure of the NPOESS program – specifically, NOAA and DoD would be responsible for different orbits. 8) 9) 10)
- NOAA responsible for the afternoon orbit - JPSS
- DoD responsible for the early morning orbit - DWSS (Defense Weather Satellite System)
- Partnership with EUMETSAT would continue for mid-morning orbit
- Both agencies would share a common ground system.
• Restructure codified and executed through:
- National Space Policy
- Administration's Implementation Plan for Polar-orbiting Environmental Satellites
- NPOESS Deputies Meeting Summary
- Series of DoD Acquisition Decision Memorandums: Continued support to NPP; Close out of the IPO; Transfer of sensors and ground system from DoD to NOAA/NASA; Identified sensor suite on DWSS.
The Administration decision for the restructured JPSS (Joint Polar Satellite System) will continue the development of critical Earth observing instruments required for improving weather forecasts, climate monitoring, and warning lead times of severe storms. NASA's role in the restructured program will be modeled after the procurement structure of the successful POES (Polar Operational Environmental Satellite) and GOES (Geostationary Operational Environmental Satellite) programs, where NASA and NOAA have a long and effective partnership. The partner agencies are committed to maintaining collaborations towards the goal of continuity of Earth observations from space.
Note: Since this transition, the DWSS satellite program has been canceled and replaced with the WFO (Weather Follow On) program. As part of the restructuring of the program, some responsibilities have been shifted to accomplish the environmental and climate observing missions. For JPSS, NASA's Goddard Space Flight Center has the responsibility for the acquisition for the afternoon orbit satellites, along with the acquisition, system engineering and integration for the Ground System (GS) for the US next-generation of weather and climate satellites. After the start of the JPSS program, the DWSS, which was to be responsible for the early morning orbit satellites, was cancelled due to lack of funding. EUMETSAT (European Organization for the Exploitation of Meteorological Satellites) will be relied on for the mid-morning orbit satellites of the MetOp series (Ref. 113).
• The JPSS program successfully completed two key reviews in July 2013 at NASA/GSFC. The JPSS program is continuing on schedule and on budget toward the March 2017 launch of the JPSS-1 polar-orbiting weather satellite. NASA is developing and acquiring the JPSS-1 mission for NOAA (National Oceanic and Atmospheric Administration). 11)
Figure 1: JPSS implements US civil commitment inter-agency and international agreements to afford a 3-orbit global coverage (image credit: NOAA, NASA)
Figure 2: JPSS overview (image credit: NOAA, NASA, Ref. 1)
The restructured Joint Polar Satellite System is planned to provide launch readiness capability in FY 2015 and FY 2018 (with launches of JPSS-1 in 2017 and JPSS-2 in 2022, respectively) in order to minimize any potential loss of continuity of data for the afternoon orbit in the event of an on orbit or launch failure of other components in the system. Final readiness dates will not be baselined until all transition activities are completed.
The United States JPSS (Joint Polar Satellite System) is the new generation of POES (Polar Operational Environmental Satellites) in the early afternoon sun-synchronous orbit. The Joint NOAA/NASA Suomi-NPP (National Polar Partnership ) mission is the first of the JPSS missions. It has achieved nearly four years of successful on-orbit observations and was declared primary satellite for weather in May of 2014. 12)
Table 1: JPSS overview — it is integral to 3-orbit global polar coverage as outlined in Figure 1
Figure 3: NOAA & Partner polar weather satellite programs - continuity of weather observations, as of April 2015 (image credit: NOAA) 13)
Figure 4: NOAA POES continuity of weather observations (image credit: NOAA)
Figure 5: Simplified schematic composition of the JPSS system (image credit: NASA, NOAA)
The JPSS spacecraft are procured at NASA/GSFC. NASA in turn awarded a contract to BATC (Ball Aerospace and Technologies Corporation) of Boulder, CO to design and develop the JPSS-1 spacecraft bus, the OMPS (Ozone Mapping and Profiler Suite) instrument, integrating all instruments, and performing satellite-level testing and launch support. 14) 15)
JPSS-1, a clone of the Suomi-NPP (also referred to as SNPP) satellite, employs the BCP-2000 (Ball Commercial Platform -2000) spacecraft bus.
• 3-axis stabilized (50 arcsec control, 21 arcsec knowledge, and 75 m position)
• Launch mass of 2540 kg
• Power: 1932 W (BOL)
• For JPSS-1, Ball is converting the NPP spacecraft design from IEEE 1394 (FireWire) to a SpaceWire databus protocol for use by the CrIS and the VIIRS instruments.
• Ka-band 300 Mbit/s downlink. In addition, a backup Ka-band SMD (Science Mission Data) downlink is added for TDRSS (Tracking and Data Relay Satellite System) transmissions (to improve future latency issues). 16)
• X-band 15 Mbit/s HRD (High Rate Data) direct broadcast to users
• Lifetime: 7 years
Figure 6: Illustration of the deployed JPSS-1 spacecraft (image credit: NASA, NOAA) 17)
Figure 7: JPSS-1 spacecraft zenith deck layout (left) and nadir deck layout (right), image credit: BATC 18)
JPSS development status:
• October 4, 2018: Last month, as satellites fed a steady stream of data into models tracking the paths of Hurricane Florence and Typhoon Mangkhut, the next in a fleet of satellites designed to monitor weather and climate cleared its CDR (Critical Design Review). 19)
- JPSS-2 (Joint Polar Satellite System-2) will join NOAA-20 (former JPSS-1) in a series of polar-orbiting satellites to monitor the Earth's atmosphere, land and oceans. NASA builds the JPSS series of satellites, and NOAA will operate them.
- It will measure the temperature and moisture of our atmosphere, and the knowledge of that is really what drives the accuracy of our weather forecasts," said Greg Mandt, NOAA director of the Joint Polar Satellite System program at NASA's Goddard Space Flight Center, Greenbelt, MD.
- Passing the CDR, a technical review, means that design and analysis of the satellite system, which includes its ground system and flight plan, is complete, and that the project is ready to continue in its next phases: fabrication, assembly, integration and testing.
- The CDR was conducted by a standing review board of 16 members, who are independent of the program and experts in various fields, including electrical and mechanical engineering, weather forecasting and science, ground systems, ground stations, and budgeting and schedule.
- Like its polar-orbiting cousins, JPSS-2 will scan our planet as it orbits from pole to pole, crossing the equator 14 times a day. In the process, its onboard instruments will snap pictures and capture data that will inform seven-day weather forecasts and extreme weather events.
Figure 8: Northrop Grumman Information Systems (NGIS) technicians install the flight harnesses onto the JPSS-2 structure on 9 August 2018 (image credit NGIS)
- Polar sounders provide roughly 85 percent of the data used in forecast models. But weather is only part of the picture. The spacecraft's instruments will also tell us about wildfires, volcanoes, atmospheric ozone, ice loss and sea surface temperatures.
- "In our ground segment design for JPSS-2, we have shown that we understand what changes are needed, and we are well prepared to go to implementation," said Heather Kilcoyne, the NOAA ground segment project manager for JPSS at NASA Goddard. "It's not enough to just have a satellite up there. Our design covers the changes needed end to end to ensure our products actually get used by forecasters and researchers."
- The newest spacecraft will be nearly identical to its predecessor, NOAA-20. But, Mandt points out, the science the data feeds are always advancing. "Every year, there will be new applications discovered," he said. "Even if the instruments are the same, the use of the data will continue to expand, and we'll find new ways to use it to solve problems."
- JPSS enables forecasters and scientists to monitor and predict weather patterns with greater accuracy and to study long-term climate trends by extending the more than 30-year satellite data record.
• July 17, 2018: NASA has awarded Raytheon's Intelligence, Information and Services business $59 million for additional work on NOAA's JPSS (Joint Polar Satellite System) CGS (Common Ground System) project. 20)
- The changes are necessary to launch America's next polar satellite, JPSS-2, in 2021. The project recently completed the critical design review for the work, and compatibility testing between the satellite and ground system will begin in early 2020. Svalbard, Norway, is the location of the northernmost Joint Polar Satellite System Common Ground System station.
- Developed by NASA for NOAA, the JPSS CGS collects and disseminates observations from polar-orbiting weather satellites from the United States, Europe and Japan. The new contract brings the total value to just under $2 billion. In addition to changes to the command and control system and orbital dynamics system that will maneuver the JPSS-2 satellite while in space, the contract also covers upgrades to the system's simulation and cyber security capabilities, as well as expansion of the system's wide area network and security incident response team.
Figure 9: Svalbard, Norway, is the location of the northernmost Joint Polar Satellite System CGS (Common Ground System) station (image credit: Raytheon)
• May 25, 2018: NASA has exercised options under the Rapid Spacecraft Acquisition III (Rapid III)contract for two additional Joint Polar Satellite System (JPSS) spacecraft to be built for the National Oceanic and Atmospheric Administration (NOAA). 21)
- Orbital ATK of Dulles, Virginia, will build NOAA's Joint Polar Satellite System JPSS-3 and -4. The contract value is $460 million and the period of performance will extend through 2026. The work will be performed at Orbital ATK's facility in Gilbert, Arizona.
- Orbital, which currently is developing the JPSS-2 spacecraft, will design, develop, fabricate, integrate, test and provide post-delivery support for the third and fourth spacecraft in the series.
• September 5, 2017: NOAA's JPSS-1 satellite arrived at Vandenberg Air Force Base in California on Sept. 1, 2017, to begin preparations for a November launch. 22)
- After its arrival, the JPSS-1 spacecraft was pulled from its shipping container, and is being prepared for encapsulation on top of the rocket that will take it to its polar orbit at an altitude of 824 km above Earth. JPSS-1 is the first in a series of NOAA's four next-generation, polar-orbiting weather satellites.
Figure 10: Photo of JPSS-1, arriving at the Astrotech Processing Facility at Vandenberg Air Force Base in California (image credit: NASA, Michael A. Starobin)
• March 6, 2017: NASA's Launch Services Program has selected United Launch Alliance's (ULA's) proven Atlas V vehicle to launch the Joint Polar Satellite System (JPSS-2) mission, the third in the nation's new generation polar-orbiting operational environmental satellite system—this award resulted from a competitive Launch Service Task Order evaluation under the NASA Launch Services II contract. 23)
- The JPSS-2 mission is scheduled to launch in the summer of 2021 from Space Launch Complex-3 at Vandenberg Air Force Base in California. This mission will launch aboard an Atlas V 401 vehicle.
• On 15 December 2016, Europe and the US achieved another milestone in the cooperation on meteorological satellite systems when Marc Cohen, EUMETSAT Associate Director for LEO Programs and Harry A. Cikanek III, NOAA Director, Joint Polar Satellite System signed the plan that will implement the JPS (Joint Polar System). 24)
- The Polar System PIP (Program Implementation Plan) encompasses the space and ground segments associated with EUMETSAT's Polar System Second Generation (EPS-SG) and the JPSS ( Joint Polar Satellite System) of NOAA ( National Oceanic and Atmospheric Administration). It also regulates the use of assets and operations as well as access to third party mission products such as the Copernicus Earth Observation Program of the EU and the NOAA COSMIC (Constellation Observing System for Meteorology Ionosphere and Climate) missions and follow-on partnerships.
• July 7, 2016: As highlighted in a May 2016 report of GAO (Government Accounting Office), the NOAA JPSS program has continued to make progress in developing the JPSS-1 satellite for a March 2017 launch. However, the program has experienced technical challenges which have resulted in delays in interim milestones. In addition, NOAA faces the potential for a near-term gap in satellite coverage of 8 months before the JPSS-1 satellite is launched and completes post-launch testing (Figure 11). 25)
- However, uncertainties remained on the best timing for launching these satellites, in part because of the potential for some satellites already in orbit to last longer. NOAA did not provide sufficient evidence that it had evaluated the costs and benefits of launch scenarios for these new satellites based on updated life expectancies. Until this occurs, NOAA may not make the most efficient use of investments in the polar satellite program.
Figure 11: Timeline for a Potential Gap in Polar Satellite Data in the Afternoon Orbit. The GAO analysis is based on NOAA and NASA data (image credit: GAO)
• NOAA's JPSS-1 satellite, the second in the JPSS satellite series, is slated for launch in early 2017 aboard a Delta-2 launch vehicle from Vandenberg Air Force Base in California. To prepare, the spacecraft is currently going through an array of tests designed to simulate the extreme environments the satellite may experience during launch and while in orbit. During the testing period, JPSS-1 and its instruments will be subjected to a variety of harsh conditions, including acoustical bombardment, intense vibration, electromagnetic fields, thermal vacuum environments and ground system compatibility tests. 26)
- The tests are taking place at BATC where the spacecraft was assembled. The satellite will be placed inside a large vacuum chamber, where it will be exposed to a simulated space environment complete with extreme hot and cold temperatures ranging from 10 degrees Celsius above and below what it could experience in space. The satellite will also undergo vibration and acoustic testing to simulate the experience of launching into space aboard a rocket, and electromagnetic testing to ensure it is properly protected from electromagnetic phenomena in space, such as solar flares.
- JPSS-1 takes advantage of the successful technologies developed through the NOAA/NASA Suomi-NPP satellite and has a design life of seven years.
• April 22, 2016: On behalf of NOAA, NASA has awarded a sole source contract modification to Ball Aerospace & Technologies Corporation of Boulder, Colorado, for two OMPS (Ozone Mapping and Profiling Suite) instruments for flight on NOAA's JPSS (Joint Polar Satellite System) Polar Follow On JPSS-3 and JPSS-4 missions. 27)
• March 17, 2016: On behalf of NOAA, NASA has awarded a sole source contract modification to Northrop Grumman, of Azusa, California, for two ATMS (Advanced Technology Microwave Sounder) instruments for NOAA's JPSS (Joint Polar Satellite System) Polar Follow On / JPSS-3 and JPSS-4 Missions. 28)
• February 11, 2016: The fifth and final instrument, the ATMS (Advanced Technology Microwave Sounder), an instrument critical to forecasting weather three to seven days in advance, has been integrated with the JPSS-1 satellite. This marks a very significant milestone for the JPSS program. Soon, the spacecraft will be prepared for the environmental testing phase which is the next step toward launch. 29)
- Compared with NOAA's legacy microwave sounders, ATMS offers more channels and better resolution and collects a wider swath of data. ATMS will be operating in tandem with CrIS (Cross-track Infrared Sounder) aboard the JPSS-1 satellite. By working together to cover more of the electromagnetic spectrum (microwave and infrared), ATMS and CrIS will provide coverage of a broad range of weather conditions.
- ATMS is built by Northrop Grumman in Azusa, California and was delivered to BATC in Boulder, Colorado where it was integrated with the spacecraft. ATMS currently flies on the NOAA/NASA Suomi NPP satellite mission and will fly on the JPSS-1, JPSS-2, JPSS-3, and JPSS-4 satellite missions.
Figure 12: Ball Aerospace technicians lower the ATMS instrument onto the JPSS-1 spacecraft (image credit: BATC)
• Fall 2015: The solar panel array on NOAA's polar-orbiting satellite JPSS-1 spacecraft successfully completed deployment testing at BATC. Engineers unfurled the three panels of the solar array on a special friction reducing floor that helps simulate deployment in the zero-gravity environment of space. The solar array is folded up at launch and deploys on orbit, resembling a giant black wing and generating more than 2775 W of power for NOAA's JPSS-1 satellite. 30)
• June 30, 2015: BATC has powered the JPSS-1 satellite for the first time. Powering on of the satellite is a key milestone to delivery. Following powering on, the satellite performed within specifications. 31)
- Ball earlier completed integration of four of five JPSS-1 flight instruments. The latest milestone means the satellite is moving toward environmental testing by early 2016 with on-time delivery scheduled for late 2016.
Figure 13: JPSS-1 has been powered-on for the first time, advancing the polar-orbiting environmental satellite toward environmental testing and delivery in 2016 (image credit: BATC)
• April 9, 2015: The CrIS (Cross-track Infrared Sounder) has been successfully integrated with the spacecraft. CrIS follows successful integration of the Ozone Mapping and Profiler Suite-Nadir (OMPS-N) instrument, the Clouds and the Earth's Radiant Energy System (CERES), and the Visible Infrared Imaging Radiometer Suite (VIIRS). 32)
- Following integration of the final instrument to fly on JPSS-1, ATMS (Advanced Technology Microwave Sounder) later this year, the JPSS-1 satellite will enter environmental testing. 33)
Figure 14: Photo of the CrIS instrument which is being moved into position just prior to integration with the JPSS-1 spacecraft (image credit: BATC)
• March 10, 2015: The VIIRS (Visible Infrared Imaging Radiometer Suite) has been successfully integrated on- board NOAA's Joint Polar Satellite System-1 (JPSS-1) satellite. The VIIRS instrument, built by the Raytheon Company in El Segundo, California, is the third instrument to be integrated on the spacecraft by Ball Aerospace & Technologies Corp. in Boulder, Colorado. 34)
• Feb. 18, 2015: The CrIS (Cross-track Infrared Sounder) has completed its pre-shipment review. The completion of the development of the CrIS instrument marks another important step in the on-time completion of the critical instruments for the JPSS-1 spacecraft. 35)
• June 17, 2014: The CERES (Clouds and the Earth's Radiant Energy System) instrument, was delivered to Ball Aerospace for spacecraft integration on June 17, 2014. 36)
• June 12, 2014: The OMPS instrument successfully completed its pre-shipment review. 37)
• April 25, 2014: CERES, the first of five instruments that will fly on JPSS-1, successfully completed pre-shipment review last week. 38)
• March 2014: BATC has applied power to the JPSS-1 spacecraft bus for the first time, a significant milestone for achieving on-time delivery to NOAA. Power-on is the first time that the spacecraft bus is operated as a system with the core EDPS (Electrical Power & Distribution System) and the integrated components of the C&DH (Command & Data Handling) subsystem. Power will be cycled on/off continuously over the next nine months of spacecraft integration and testing. 39)
• February 2014: BATC has successfully completed the SpaceWire interoperability test for the JPSS-1 satellite and has begun spacecraft bus integration. The scope of the test, conducted under both normal and fault conditions, proved the functionality of links using flight-like engineering models of key JPSS-1 spacecraft bus subsystems and engineering models for VIIRS and CrIS. The three additional JPSS-1 instruments include the ATMS , CERES, and the Ball Aerospace-built OMPS (Ozone Mapping and Profiler Suite). 40)
• In December 2012, a four-day delta Critical Design Review (dCDR) of work was conducted at BATC with representatives of NASA and NOAA and the instrument providers. With this successful review, the spacecraft has now been approved to proceed into implementation. 41)
• April 2014: CERES (Clouds and the Earth's Radiant Energy System), the first of five instruments that will fly on JPSS-1, NOAA's next polar orbiting environmental satellite, successfully completed pre-shipment review. 42)
Figure 15: JPSS-1 satellite, including instruments and other key components (image credit: NOAA, BATC)
Orbit: Sun-synchronous orbit, altitude of 824 km, inclination = 98.7º, period = 101 minutes, ground track: 20 km repeat accuracy at the equator with 20 day repeat cycle, LTAN = 13:30 hours ±10 minutes.
Once in orbit, the JPSS-1 spacecraft will be known as NOAA- 20 (once in orbit). This naming ensures the satellite will be identified consistently with previous NOAA operational polar satellite missions dating back to 1978. The previous satellite launched in 2011, the NOAA/NASA Suomi NPP satellite, serves as a bridge from legacy missions to JPSS. 47)
JPSS-1 is the first in NOAA's series of four, next-generation operational environmental satellites designed to circle the Earth in a polar orbit. JPSS represents significant technological and scientific advancements in observations used for severe weather prediction and environmental monitoring. This data is used by NOAA's National Weather Service for numerical forecast models, ultimately helping emergency managers make timely decisions on life-saving early warnings and evacuations.
Secondary payloads (ELaNa-14, Ref. 45):
• RadFxSat (Radiation Effects Satellite, Fox-1B), a 1U CubeSat of AMSAT and Vanderbilt University, Nashville, TN, USA.
• EagleSat, a 1U CubeSat of ERAU (Embry-Riddle Aeronautical University), Prescott, AZ, USA.
• MakerSat-0, a 1U CubeSat of NNU (Northwest Nazarene University) and of Caldwell High School of Nampa, Idaho, USA.
• MiRaTA (Microwave Radiometer Technology Acceleration), a 3U CubeSat of MIT (Massachusetts Institute of Technology), Cambridge, MA, USA.
• BRRM (Buccaneer Risk Mitigation Mission), a 3U CubeSat technology mission of UNSW (University of New South Wales), Canberra, Australia and DST (Defence Science and Technology) group. The goal is to calibrate JORN (Jindalee Over-the-Horizon Radar Network).
• July 2018: Since launch in November 2017, the VIIRS (Visible Infrared Imaging Radiometer Suite) on-board the NOAA-20 /JPSS-1 satellite has completed its initial intensive on-orbit check-outs and several key calibration and validation activities scheduled to help evaluate sensor at launch performance. 48)
- Like its predecessor aboard the Suomi NPP spacecraft launched in October 2011, the VIIRS collects data in 22 spectral bands. In addition to a day and night band (DNB), spectral bands (M1-M11 and I1-I3) with wavelengths from 0.41 to 2.2 µm are referred to as the reflective solar bands (RSB) and other bands (M12-16 and I4-I5) covering wavelengths from 3.7 to 12 µm are referred to as the thermal emissive bands (TEB). M1-M5, M7, and M13 can make observations at either high- or low-gain and the DNB is capable of collecting data at three different gain stages.
- As shown in Figure 16, the VIIRS on-orbit calibration is performed by the OBCs that include a solar diffuser (SD) and a solar diffuser stability monitor (SDSM) for the RSB and a blackbody (BB) for the TEB. Lunar observations are also made regularly as a supplement to instrument on-board calibration. The SD calibration is normally performed every orbit. The SDSM is currently operated on a daily basis. The BB warm-up/cool-down (WUCD), initially planned on a quarterly basis, will be executed less frequently in future operation. Like Suomi NPP, lunar observations will be scheduled 8-9 times per year at nearly identical phase angles (-51º). The first lunar calibration for N-20 VIIRS was performed on December 29, 2017 via a spacecraft roll maneuver.
Figure 16: VIIRS instrument and its on-board calibrators (OBCs), image credit: NASA, NOAA
- Since launch, a number of calibration improvements have been made. Using data collected during spacecraft yaw maneuvers, the SD and SDSM screen transmission functions are derived, updated and used for on-orbit calibration. Compared to pre-launch measurements, on-orbit yaw maneuver data provide fine details, both geometrically (more angles) and spectrally (more wavelengths). The TEB RVS characterized using pitch maneuver data shows good agreement with pre-launch results. DNB straylight correction strategy is based on lessons from Suomi NPP and needs extra effort to address effects in the extended zone (not in Suomi NPP). Similar to Suomi NPP, the lunar long-term trend will be used to support RSB solar calibration. From the perspective of long-term data records, the calibration consistency between Suomi NPP and N-20 VIIRS will likely be a major challenge and requires more studies.
• May 30, 2018: The NOAA-20 (JPSS-1) satellite is now operational. Advanced data will detect environmental hazards, improve weather forecasts. Weather forecasters officially have a new tool in their arsenal, as the first satellite in NOAA's new Joint Polar Satellite System has passed rigorous testing and is now operational. 49)
- Launched in November 2017 as JPSS-1 and renamed NOAA-20 once it reached orbit, the satellite features the latest and best technology NOAA has ever flown in a polar orbit to capture more precise observations of the world's atmosphere, land and waters. Data from the satellite's advanced instruments will help improve the accuracy of 3-to-7 day forecasts.
- "Improved weather forecasts can save lives, protect property and provide businesses and communities valuable additional time to prepare in advance of dangerous weather events," said Secretary of Commerce Wilbur Ross.
- NOAA-20 provides NOAA's National Weather Service with global data for numerical weather prediction models used to develop timely and accurate U.S. weather forecasts. In addition, high-resolution imagery from the satellite's VIIRS (Visible Infrared Imaging Radiometer Suite) will enable the satellite to detect fog, sea-ice formation and breaking in the Arctic, volcanic eruptions and wildfires in their very early stages. This advanced modeling and imagery information, shared with international and governmental partners, will help businesses, the emergency preparedness and response communities and individuals make the best decisions possible in the face of weather-related hazards.
- NOAA-20 joins Suomi NPP – the NOAA-NASA demonstration satellite launched in 2011 – giving the U.S. the benefit of two sophisticated spacecraft in nearly the same orbit. Each circles the Earth in a polar orbit 14 times a day, collecting global observations that form the basis for U.S. weather prediction.
- "NOAA-20 is especially beneficial for tracking developing storms in the Arctic, Alaska and Antarctica. Forecasts for these remote regions are critical for the U.S. fishing, energy, transportation and recreation industries, which operate in some of the harshest conditions on the planet," said Neil Jacobs, Ph.D., assistant secretary of commerce for environmental observation and prediction.
- JPSS-2, the second in the series, is scheduled to be launched in 2021, followed by JPSS-3 in 2026 and JPSS-4 in 2031. JPSS satellites are designed to operate for seven years, with the potential for several more years. The JPSS mission will deliver its critical data and information for at least the next two decades to support a Weather-Ready Nation.
• April 20, 2018: NOAA's newest polar-orbiting satellite, NOAA-20 (JPSS-1), captured this magnificent view of the Earth's North Pole on April 12, 2018 (Figure 17). By passing over the pole 14 times a day, the satellite's VIIRS instrument was able to create this composite image of the planet, centered over the frozen Arctic, from 824 km above Earth. The outline of the North American continent is visible at the bottom of the Earth's disk, while the Sahara Desert and northern Africa appear on the right hand side. 50)
- Scientists use the data from NOAA-20's VIIRS sensor to create the "true-color" imagery shown here. While true-color images appear to be simple photographs of Earth, they are actually created by combining data from the three color channels on the satellite's VIIRS instrument sensitive to the red, green and blue (or RGB) wavelengths of light into a single composite image.
- As the backbone of the global satellite observing system, NOAA-20 circles the Earth from pole to pole and crosses the equator about 14 times daily, providing full global coverage twice a day. The satellite's instruments measure temperature, water vapor, ozone, precipitation, fire and volcanic eruptions, and can distinguish snow and ice cover under clouds. This data enables more accurate weather forecasting for the United States and the world.
Figure 17: NOAA-20 Shares New View of the North Pole for Earth Day (image credit: NOAA/NESDIS)
• April 12, 2018: Ball Aerospace completed the handover of NOAA's advanced next-generation polar-orbiting weather satellite, the Joint Polar Satellite System (JPSS-1), to NASA following a successful satellite acceptance review. Launched on Nov. 18, 2017, JPSS-1, now known as NOAA-20, is the most advanced operational environmental system ever developed by government and industry, and significantly increases the timeliness and accuracy of forecasts three to seven days in advance of severe weather events. 51)
- The acceptance review confirmed the satellite met its on-orbit requirements, and the spacecraft and the five instruments are performing as expected. NOAA-20 is proceeding on schedule for operations handover from NASA to NOAA. NOAA will determine when the satellite data will be used in NOAA products and services.
- "Everyone on our planet is affected by weather – especially adverse weather – in some way, and relies on systems like JPSS that are part of our nation's critical infrastructure, just like roads and bridges," said Rob Strain, president, Ball Aerospace. "The NOAA-20 satellite, with its sophisticated instruments, is ready to deliver better, more accurate data for operational weather forecasting, which will help save lives and resources, protect property and support our economy, now and well into the future."
- NOAA-20 is now circling in the same orbital plane as the Ball-built Suomi National Polar-Orbiting Partnership (Suomi NPP) satellite, allowing important overlap in observational coverage to occur for critical instrument calibration and validation activities, which in turn lead to more accurate weather forecasting. NOAA-20 crosses the equator about 14 times daily - providing full global coverage twice a day, making precise measurements of the atmosphere, ocean and land surface, measurements that are critical for the nation's weather models and forecasters.
- Ball Aerospace designed and manufactured the NOAA-20 spacecraft and the Ozone Mapping and Profiler Suite-Nadir (OMPS-N) instrument; integrated all five of the satellite's instruments, including those built by industry partners Harris, Raytheon and Northrop Grumman; and performed satellite-level testing and launch support.
- The JPSS missions are funded by NOAA to provide global environmental data in low-Earth polar orbit. NASA is the acquisition agent for the flight systems, launch services and components of the ground segment. Ball is also under contract to build the OMPS instruments for NOAA's follow-on JPSS-2, JPSS-3 and JPSS-4 missions.
• March 23, 2018: It is the first category 5 cyclone of 2018 and the strongest to hit Darwin, Australia, since 1974. But so far, Cyclone Marcus has directed most of its fury into the Indian Ocean, rather than onto landmasses. 52)
- At 2 p.m. local time (06:00 UT) on March 21, 2018, VIIRS (Visible Infrared Imaging Radiometer Suite) on JPSS-1 (Joint Polar Satellite System–1) satellite acquired a natural-color image (Figure 18) of Cyclone Marcus off the northwest coast of Australia. At the time, the storm had sustained winds of 125 knots (145 miles/230 km/hour) according to estimates from the U.S. Joint Typhoon Warning Center. It was a category 5 storm on the Australian cyclone scale.
- Marcus first developed as a tropical storm on March 15, 2018, and reached category 2 cyclone strength on the Australian scale on March 17 (a strong tropical storm compared to Atlantic hurricanes). The cyclone blew through Darwin with wind gusts as high as 130 km/hour. The storm knocked out electricity for more than 20,000 people, and thousands of trees were destroyed, including many that were planted in the wake of Cyclone Tracy of 1974.
Figure 18: Natural color image of Cyclone Marcus off the northwest coast of Australia, acquired with VIIRS on JPSS-1 on 21 March 2018 (image credit: NASA image by Jeff Schmaltz, LANCE/EOSDIS Rapid Response. Story by Mike Carlowicz)
- Cyclone Marcus skirted Northern Territory and Western Australia as it moved westward over very warm water and reached category 4 strength by March 21. The map of Figure 19 shows the SSTs (Sea Surface Temperatures) in the equatorial Indian Ocean on March 21, 2018. The data were compiled by Coral Reef Watch, which blends observations from the Suomi NPP, MTSAT, Meteosat, and GOES satellites, and computer models. The dotted white line across the Indian Ocean shows the cutoff between waters above and below 27.8ºC, a threshold scientists believe to be necessary to fuel a cyclone. The yellow-to-red line represents the storm's track.
- As of March 22, forecasters were calling for Marcus to remain at severe strength for another day, then weaken rapidly as it turns south toward cooler water. The remnants of the storm could make landfall around Perth as a tropical depression.
Figure 19: Coral Reef Watch SSTs blending observations from the Suomi NPP, MTSAT, Meteosat, and GOES satellites, and computer models. The dotted white line across the Indian Ocean shows the cutoff between waters above and below 27.8ºC, a threshold scientists believe to be necessary to fuel a cyclone. The yellow-to-red line represents the storm's track (image credit: NASA Earth Observatory, image by Joshua Stevens, using SST data from Coral Reef Watch, and storm track information from Unisys, story by Mike Carlowicz)
• January 16, 2018: The covers on the CERES FM6 (Clouds and the Earth's Radiant Energy System Flight Model 6) opened Jan. 5, allowing it to scan Earth for the first time. 53)
- CERES FM6 began scanning Earth at approximately 1:25 p.m. (EST) Jan. 5. On Jan. 10, scientists used those scans to produce the "first light" images.
- Built by Northrop Grumman, funded by NOAA and managed by NASA/LaRC (Langley Research Center) in Hampton, Virginia, in coordination with the JPSS program, CERES FM6 is the last in a series of instruments going back to the late 1990s that measure the solar energy reflected by Earth, the heat the planet emits, and the role of clouds in that process.
- "CERES FM6 is the seventh and final copy since we first launched the first CERES instrument in 1997. It is the most accurate broadband radiometer that NASA/NOAA have flown as a result of a more rigorous prelaunch calibration campaign than previous instruments," said CERES Project Scientist Kory Priestley. "We were able to take knowledge from on-orbit operations and apply it to this flight model. We've done a better job of building and characterizing the instrument, and with hope that will bear fruit as the mission is flown."
- "The robustness of the CERES instruments already on-orbit, having exceeded their design lifetimes by a factor of two to three, is testament to the work of the dedicated team of engineers at Northrop Grumman," Priestley said. "The scientific discoveries the community will make by utilizing these datasets will benefit humanity for decades to come."
Figure 20: In this shortwave image from CERES FM6, the white and green shades represent thick cloud cover reflecting incoming solar energy back to space. Compare that with the darker blue regions, which have no cloud cover, to get a sense for just how much clouds can affect the balance of incoming and outgoing energy on Earth (image credit: NASA)
Figure 21: In this longwave image from CERES FM6, heat energy radiated from Earth is represented by shades of yellow, red, blue and white. Bright yellow regions are the hottest and emit the most energy out to space. Dark blue and bright white regions, which represent clouds, are much colder and emit the least energy (image credit: NASA)
- Five other CERES instruments are flying on three other satellites. Their data helps scientists validate models that calculate the effect of clouds on planetary heating and cooling. The same data can also be helpful for improving near-term, seasonal forecasts influenced by weather events such as El Niño and La Niña. El Niño and La Niña are climatic fluctuations in the temperature of the tropical Pacific Ocean that can influence weather globally.
- "The successful launch of CERES FM6 and acquisition of initial data is fantastic news," said David Considine, program manager for NASA's Modeling, Analysis and Prediction program. "Its data will help us to understand the critical role that clouds play in the Earth system, and shows the value to the Nation of the NASA and NOAA collaboration leading to this achievement."
- The CERES data record extends back to 1997. Prior to CERES, the ERBE (Earth Radiation Budget Experiment) collected similar data beginning in 1984. The two NASA programs demonstrate NASA's long-term involvement in measuring Earth's energy balance going back more than 30 years.
- "Northrop Grumman is proud to be a collaborative partner with NASA and NOAA on this successful CERES mission. Between the seven CERES instruments and their ERBE predecessors, we have had a relationship in Earth radiation budget measurements that now spans over three decades," said Northrop Grumman CERES Program Manager Sean Kelly. "The CERES instruments continue to reliably provide the climate data record necessary for monitoring, processing and analyzing critical data for the Earth science community. CERES is one of the most highly calibrated, highly reliable instruments on-orbit today."
• December 13, 2017: Twenty-five days after JPSS-1 (NOAA-20) was launched into Earth orbit, NOAA-20 sent back its first VIIRS (Visible Infrared Imaging Radiometer Suite) science data on December 13, 2017, as part of a series of instrument activation and checkouts that is taking place before the satellite goes into fully operational mode. VIIRS is one of the key five instruments onboard NOAA-20 that will improve day-to-day weather forecast and environmental monitoring, while extending the record of many long-term observations of Earth's climate. 54)
- This VIIRS true color image captured the aggressive wildfires across the Southern California region which forced thousands to flee their homes. As of Wednesday morning, December 13, 2017, the Thomas Fire was the fourth-largest fire in California history, and it continues to generate smoke and plumes as it enters its second week. The fire spanned more than 370 square miles (>95,800 hectares) and remains the strongest blaze for firefighters to battle in Ventura and Santa Barbara counties.
Figure 22: The NOAA-20 VIIRS first light image captures one of the largest wildfires in California history (image credit: NOAA Visualization Lab and NESDIS/STAR)
• November 30, 2017: Eleven days after JPSS-1 launched into Earth orbit, the satellite, now known as NOAA-20, has sent back its first ATMS (Advanced Technology Microwave Sounder) science data as part of a series of instrument startups and checkouts that will take place before the satellite goes into full operational mode. The NOAA-20 satellite carries five instruments that will improve day-to-day weather forecasting while extending the record of many long-term observations of Earth's climate. 55)
- ATMS receives 22 channels of radio waves from 23 to 183 gigahertz. Five water vapor channels, combined with other temperature sounding channels are used to provide the critical global atmospheric temperature and water vapor needed to provide accurate weather forecasts out to seven days. ATMS also maps global precipitation, snow and ice cover.
Figure 23: This image uses ATMS data to depict the location and abundance of water vapor (as associated with antenna temperatures) in the lower atmosphere, from the surface of the Earth to 5 kilometers altitude. Transparent/grey colors depict areas with less water vapor, while blue-green and purple colors represent abundant water in all phases (vapor, clouds, and precipitation) in low and middle latitudes. In the polar regions, purple depicts surface snow and ice. Water vapor distribution in space and time is a critical measurement for improving global weather forecasts. With detailed vertical information, forecasters can better identify the transport of water vapor associated with jet streams, which can fuel severe weather events (image credit: NOAA, NASA)
• November 21, 2017: JPSS-1 not only reached polar orbit on Saturday, November 18; it also officially became known as NOAA-20. 56)
• November 18, 2017: All CubeSats have been deployed! P-POD 1 released EagleSat-1, RadFXSat and MakerSat-0; Buccaneer deployed from P-POD 2; and MiRaTA deployed from P-POD 3. The CubeSats all are flying solo to begin their missions. 57)
- Orbit: All CubeSats were deployed into an elliptical sun-synchronous orbit with a perigee of 450 km and an apogee at 810 km, inclination = 97.2º.
• Approximately 63 minutes after launch the solar arrays on JPSS-1 deployed and the spacecraft was operating on its own power. JPSS-1 will be renamed NOAA-20 when it reaches its final orbit. Following a three-month checkout and validation of its five advanced instruments, the satellite will become operational. 58)
- JPSS-1 will join the joint NOAA/NASA Suomi National Polar-orbiting Partnership satellite in the same orbit and provide meteorologists with observations of atmospheric temperature and moisture, clouds, sea-surface temperature, ocean color, sea ice cover, volcanic ash, and fire detection. The data will improve weather forecasting, such as predicting a hurricane's track, and will help agencies involved with post-storm recovery by visualizing storm damage and the geographic extent of power outages.
Sensor complement: (ATMS, CrIS, CERES, OMPS, VIIRS)
Contracts with instrument developers: NASA signed the final contract on June 19, 2012 with Raytheon Space and Airborne Systems of El Segundo, CA, for the VIIRS (Visible Infrared Imager Radiometer Suite) instrument. The ATMS (Advanced Technology Microwave Sounder) contract was signed with Northrop Grumman Electronic Systems of Azusa, CA, in April, 2012. NASA completed the JPSS-1 spacecraft and the OMPS (Ozone Mapping and Profiler Suite) instrument contract with Ball Aerospace in 2011. The contract to Raytheon Intelligence and Information Systems for the JPSS Ground System was also completed in 2011, as was the CrIS (Cross-track Infrared Sounder) instrument contract with ITT Exelis (Ref. 14). 59) 60)
Figure 24: JPSS-1 flight configuration and allocation of the instrument suite, identical to the one of NPP (image credit: NASA, NOAA) 61)
Note: Due to JPSS-1 (NPP Clone) bus limitations, the JPSS FF-1 (JPSS Free Flyer-1) mission was developed, a complementary mission to the JPSS-1 satellite. It will fly the instruments, which were originally planned for the former NPOESS satellites, but could not be accommodated on the JPSS satellites.
JPSS Free Flyer-1 will accommodate the following instruments:
• TSIS (Total Solar Irradiance Sensor)
• A-DCS (Advanced Data Collection System)
• SARSAT (Search and Rescue) instruments.
Figure 25: The JPSS instruments (image credit: NOAA)
ATMS (Advanced Technology Microwave Sounder)
ATMS, of Suomi-NPP heritage, provides sounding observations necessary to retrieve atmospheric temperature and moisture profiles for civilian operational weather forecasting, as well as continuity of these measurements for climate monitoring. In addition to temperature and moisture profiles, some of ATMS-derived products include integrated water vapor content, cloud liquid water content, precipitation rate, snow cover and sea ice concentration.
ATMS is the next generation cross-track microwave sounder that will combine the capabilities of current generation microwave temperature sounders AMSU-A, AMSU-B and AMSU-B/MHS, into a single instrument. The ATMS draws its heritage directly from AMSU-A/B, but with reduced volume, mass and power. The ATMS has 22 microwave channels to provide temperature and moisture sounding capabilities. Sounding data from CrIS and ATMS will be combined to construct atmospheric temperature profiles at 1 degree Kelvin accuracy for 1 km layers in the troposphere and moisture profiles accurate to 15% for 2 km layers. Higher (spatial, temporal and spectral) resolution and more accurate sounding data from CrIS and ATMS will support continuing advances in data assimilation systems and NWP models to improve short- to medium-range weather forecasts beyond three days. - The ATMS instrument was developed at Northrop Grumman Electronic Systems of Azusa, CA. 62)
Figure 26: Photo of the ATMS instrument (image credit: MIT/LL, NASA)
Table 2: Summary of key instrument parameters 63)
Figure 27: Functional block diagram of ATMS (image credit: NASA)
Table 3: Channel characteristics of ATMS
Instrument calibration: The instrument includes on-board calibration sources viewed by the reflectors during each scan cycle. The calibration of the ATMS is a so-called through-the-aperture type, two-point calibration subsystem. The warm reference point is a microwave blackbody target whose temperature is monitored. In addition, cold space is viewed during each scan cycle. Both calibrations provide for the highly accurate microwave sounding measurements required by the operational and science applications of ATMS data.
There are three antenna beamwidths. The temperature sounding channels are 2.2º (Nyquist-sampling in both along-scan & down-track directions) while the humidity channels are 1.1º. Channels 1 and 2 have a larger beam width of 5.2º. This is due to the limited volume available on the spacecraft for ATMS.
The ATMS post-launch calibration/validation:
• Tasks within the phases can be categorized:
- Sensor evaluation: interference, performance evaluation, etc.
- TDR/SDR verification: geolocation, accuracy, etc.
- SDR algorithm tunable parameters: bias correction, space view sector, etc.
• Activation phase: Sensor is turned on and a sensor functional evaluation is performed; ATMS is collecting science data
• Checkout phase: Performance evaluation and RFI evaluations
• Intensive Cal/Val: Verification of SDR attributes such as geolocation, resampling, brightness temperature accuracy (simultaneous nadir overpass, double difference, radiosondes/NWP simulations, aircraft verification campaigns), and satellite maneuvers.
Figure 28: Atmospheric transmission at microwave wavelengths (image credit: MIT/LL)
ATMS provides 3 EDRs (Environmental Data Records) with CrIS:
• Atmospheric vertical moisture profile
• Atmospheric vertical temperature profile
• Pressure (surface/profile).
Table 4: Summary of ATMS and CrIS applications 64)
NUCAPS (NOAA Unique CrIS/ATMS Processing System) was developed to generate (1) spectrally and spatially thinned radiances, (2) retrieved products such as profiles of temperature, moisture, trace gases and cloud-cleared radiances, and (3) global validation products such as radiosonde matchups and gridded radiances and profiles.
These products are derived from the CrIS (Cross-track Infrared Sounder) and ATMS (Advanced Technology Microwave Sounder) currently onboard the Suomi National Polar-orbiting Partnership (S-NPP) satellite and later will be available from the Joint Polar Satellite System (JPSS-1 and JPSS-2). 65)
CrIS (Cross-track Infrared Sounder)
CrIS is the first in a series of advanced operational sounders that will provide more accurate, detailed atmospheric temperature and moisture observations for weather and climate applications. This high-spectral resolution infrared instrument will take 3-D images of atmospheric temperatures, water vapor and trace gases. It will provide over 1,000 infrared spectral channels at an improved horizontal spatial resolution and measure temperature profiles with keen vertical resolution to an accuracy approaching 1 K (the absolute temperature scale). This information will help significantly to improve climate prediction, including both short-term weather "nowcasting" and longer-term forecasting. It will also provide a vital tool for NOAA to take the pulse of the planet continuously and assist in understanding major climate shifts. The CrIS instrument is developed by ITT Exelis, Fort Wayne, Indiana.
Figure 29: Photo of the CrIS instrument (image credit: NOAA) 66)
CrIS, of HIRS/4 (POES) and AIRS (Aqua) heritage, is a high-spectral and high-spatial resolution infrared sounder for atmospheric profiling applications. The overall objective is to perform daily measurements of Earth's upwelling infrared radiation to determine the vertical atmospheric distribution (surface to the top of the atmosphere) of temperature (profiles to better than 1 K accuracy in the lower troposphere and lesser accuracy at higher altitudes), moisture (profiles to better than 20-35% accuracy depending on altitude) and pressure (profiles to better than 1.0% accuracy ) with an associated 1.0 km vertical layer resolution. The Michelson interferometer sounder has 1305 spectral channels, it covers a spectral range of 650-2550 cm-1 (or 3.9 to 15.4 µm), with a spectral resolution of 0.6525 cm-1 (LWIR), and a ground spatial resolution (IFOV) of 14.0 km (from an orbital altitude of 833 km). Each scan (with an 8-second repeat interval) includes views of the internal calibration target (warm calibration point), and a deep space view (cold calibration point). The overall instrument data rate is <1.5Mbit/s. Only photovoltaic detectors are used in the CrIS instrument. The detectors are cooled to approximately 81K using a 4-stage passive cooler with no moving parts. They have a low-risk heritage design of over 50 space units. The IFOVs are arranged in a 3 x 3 array. The swath width is 2200 km (FOV of ±50º), with 30 Earth-scene views.
The CrIS optical system was designed to provide an optimum combination of optical performance and compact packaging. Its key subsystems include a step and settle two-axis scene selection module with image motion compensation capability, a full-aperture internal calibration source, a large-aperture Michelson interferometer, a three-element all reflective telescope, a cooled aft optics module, a multiple-stage passive cooler, and an attached electronics assembly. The interferometer uses a flat-mirror Michelson configuration equipped with a dynamic alignment system to minimize misalignments within the interferometer and has a maximum optical path difference of ±0.8 cm. 67)
The "unapodized spectral resolution" requirement is defined as I/(2L), where L is the maximum optical path difference from ZOND (Zero Path Difference) to MPD (Maximum optical Path Difference). The on-axis unapodized spectral resolution for each spectral band shall be ≤to the values given in Table 5. Since L determines the unapodized spectral resolution, the nominal value for L is also given in the table. 68)
Table 5: Spectral requirements of the CrIS instrument
Instrument: The CrIS instrument consists of 6 modular assemblies: optical bench, scanning telescope, interferometer, PV focal plane arrays, 4-stage passive cooler, and electronics. The optical bench provides a stable structure for mounting all of the other assemblies. The scanning telescope scans the Earth views, the ICT (Internal Calibration Target), and deep space, and focuses the IR energy into the interferometer. The interferometer sequentially "breaks" the IR energy into the spectral bands, much like the "rainbow" from a DVD surface. The PV detectors sense the sequenced IR energy (from the interferometer), and provide an electrical signal corresponding to the incoming IR energy. The 4-stage cooler is used to cool the detectors, and hence reduce any spurious detector noise. The electronics assembly controls the instrument. It also conditions and formats the telescope scan and detector signals for output to the spacecraft. 69) 70)
• 8 cm clear aperture
• A collimator is used to perform the spatial and spectral characterizations
• 4-stage split-patch passive cooler (81 K for LWIR patch temperature, 98 K for MWIR/SWIR patch)
• High-performance PV (photovoltaic) detectors
• 3 x 3 arrays (14 km IFOVs)
• Three spectral bands (SWIR, MWIR, TIR), co-registered so that the FOVs of each band see the radiance from the same region of the Earth's atmosphere
• All-reflective telescope
• Proven Bomem plane-mirror Michelson interferometer with dynamic alignment
• Deep-cavity internal calibration target based on MOPITT design
• Two-axis scene selection module with image motion compensation
• A modular design (allowing for future addition of an active cooler and >3 x 3 arrays
The flight configuration for the CrIS DPM (Detector Preamplifier Module) consists of three spectrally separate (SWIR, MWIR and LWIR) FPAAs (Focal Plane Array Assemblies), three (SWIR, MWIR and LWIR) signal flex cable assemblies, a warm signal flex cable/vacuum bulk head assembly, and the DPM warm electronics CCAs (Circuit Card Assemblies). The FPAAs are cooled to cryogenic temperature (98 K SWIR, MWIR, 81 K for LWIR) by the detector cooler module. The cryogenic portions of the DPM (FPAAs, and signal flex cable assemblies) mate to the ambient temperature portions of the DPM (warm signal flex cable assembly and the ambient temperature portions of the transimpedance amplifier, mounted within the CCAs) through the vacuum bulk head assembly mounted on the detector cooler assembly housing. 71)
Table 6: Key performance characteristics of CrIS
CrIS calibration: The calibration of the interferometer is accomplished with both LASER wavelength calibration, and also with a Neon bulb spectral calibration. The ICT (Internal Calibration Target) consists of a highly emissive, deep-cavity blackbody, utilizing a flight-proven, MOPITT (Measurement of Pollution in the Troposphere)-heritage design. Temperature knowledge of the ICT is better than 80mK. A passive vibration isolation system is included to allow instrument operation in a 50mG environment. The instrument optics are thermally decoupled from both the structure and the instrument electronics. The overall instrument design is modular, which allows for parallel assembly and rapid instrument integration.
The primary data product of the CrIS instrument are interferograms collected from 27 infrared detectors that cover 3 IR bands and 9 FOVs. 72)
Data of CrIS will be combined in particular with those of ATMS to construct atmospheric temperature profiles at 1 K accuracy for 1 km layers in the troposphere and moisture profiles accurate to 15% for 2 km layers. 73)