ISS Utilization: ERA (European Robotic Arm)
ERA is a robotic servicing system, which will be used to assemble and service the Russian segment of the International Space Station. The European Robotic Arm (ERA) will work with the new Russian airlock, to transfer small payloads directly from inside to outside the International Space Station. This will reduce the set-up time for astronauts on a spacewalk and allow ERA to work alongside astronauts. 1)
ERA acts as a tool for: Installation, deployment and replacement of elements of the Russian Segment of the Space Station, inspection of the Russian Segment, support/transfer of EVA cosmonauts, transfer of Orbital Replacement Units and other assembly tasks. The arm consists of 2 End Effectors, 2 Wrists, 2 Limbs and 1 Elbow joint together with electronics and cameras. Both ends act as either a “hand” for the robot or the base from which it can operate.
“The Russians wanted to give their spacewalkers the option of direct control over ERA,” explains ESA robotics engineer Lodewijk Aris. “So we built this external interface along with as a pair of internal interfaces. External control is one of the attributes that make ERA unique among the Station arms. The interface is designed to endure the space environment for at least a decade – when not in use the hinged cover is closed, to protect it from thermal extremes, radiation and micrometeorites.
Figure 1: External control interface for European Robotic Arm. This rugged control panel has been designed to be used by a cosmonaut in a spacesuit, on the outside of the International Space Station (image credit: ESA, SJM Photography)
Known as the EMMI (External Man Machine Interface), it will be used to control the European Robotic Arm, which is due to reach the Station as part of Russia’s long-awaited Nauka (meaning ‘Science’) Multipurpose Laboratory Module (MLM) in July 2021.
ESA (European Space Agency) designed the European Robotic Arm (ERA) as part of its contributions to the ISS. The 11.3-m long, seven degrees of freedom robotic manipulator will be the third arm to reach the Station, following Canada’s ‘Canadarm’ and Japan’s RMS (Remote Manipulator System). Serving the Russian segment of ISS, ERA will be able to manipulate payloads of up to 8 tons, with a positioning accuracy of 5 mm. 2)
“This is a qualification model – its flight model is with Russia’s Energia company along with ERA itself. The qualification model of ERA is also here in ESTEC, which we will be using for tests and anomaly investigations post-launch.
Able to move in a similar manner to a human arm, ERA is symmetrical in design around its central elbow joint, with both ends of the arm concluding in end effectors that can function together with their wrists either as ‘shoulders’ or ‘hands’.
Its shoulder side will be connected to one of four different ‘base plates’ around the MLM, providing data and power links, while its wrist-and-hand side will be able to take payloads from the module’s airlock and place them on a selection of payload mounting units. ERA will be relocated between base plates as required.
ERA’s end effectors also feature cameras for visual inspection and screwdriver-like ‘integrated service tool’ for securing payloads using a standardized pin latch attachment system. The combination of a laser-based lighting unit and force sensor will allow precise manipulation of payloads, including installing and removing them.
As a safety feature, ERA includes a detailed virtual map of the ISS to prevent any accidental collision with Station structure – which has been kept updated as the Station grew during its wait for flight.
“The MLM, equipped with its own solar panels, an airlock and Soyuz docking port as well as ERA should offer a significant boost to ISS science,” adds Aris. “Directly after its in-orbit validation phase, ERA will have the crucial role of installing the MLM’s radiator and airlock – with backup from the ERA operations room here in the ESTEC technical center in the Netherlands – before being formally handed over to the Russians for operational use.”
Figure 2: Artist's rendition of the European Robotic Arm (ERA), image credit: ESA
ERA (European Robotic Arm) Smart Spacewalker
It is much like a human arm. It has an elbow, shoulders and even wrists. The European Robotic Arm (ERA) is the first robot able to ‘walk’ around the Russian segment of the International Space Station. 3)
Light yet powerful, the orbital arm has the ability to anchor itself to the Station and move back and forward by itself, hand-over-hand between fixed base-points. This space robot looks like a pair of compasses and has a length of over 11 m. When stretched, it could pass a football from a penalty spot to the goalkeeper.
The robot will serve as main manipulator on the Russian part of the Space Station. Its seven joints can handle multi-tonne payloads with a large range of motion for assembly tasks.
The arm and its two control stations – one for inside and another for outside the orbital outpost – will be launched into space together with the Multipurpose Laboratory Module, called ‘Nauka’, from the Baikonur Cosmodrome, in Kazakhstan, on a Russian Proton rocket. he launch is set for the summer of 2021, after two decades of technical and programmatic challenges.
The robotic arm brings new ways of operating automated machines to the orbital complex. ERA has the ability to perform many tasks automatically or semi-automatically, can be directed either from inside or outside the Station, and it can be controlled in real time or preprogrammed.
Once it starts working from its home base at the Russian Multipurpose Laboratory Module the robot arm can help install, deploy and replace elements in outer space. ERA’s first tasks in orbit, after deployment and checkouts, are to set up the airlock and install a radiator for the latest module of the Space Station.
Astronauts will use the robotic arm to save time and effort in Space Station maintenance. It will act as a tool to transfer small payloads directly from inside to outside the Space Station without the need for spacewalks, but will also help spacewalkers by transporting them around like a cherry-picker crane. Its four infrared cameras will support inspections and operations outside the Space Station.
The International Space Station already features two robotic arms: Canadarm2 and the Japanese Experiment Module Remote Manipulator System. Both play a crucial role in berthing visiting vehicles and grappling external payloads on the US and Japanese modules.
ERA comes to the stage to service the Russian segment. Even though the Multipurpose Laboratory Module will be its home base, ERA’s design and flexibility provide the freedom to move hand-over-hand around the Russian parts of the Station. It will supplement the two ‘Strela’ cargo cranes.
The mounting points on the Russian segment are optimized for the robotic arm. There is no need for ERA to manipulate spacecraft – Russian spacecraft dock automatically.
Figure 3: Human and robotic exploration with ERA (image credit: ESA)
Seven Degrees of Freedom
There is something ‘human’ about the robotic arm. A quick glance brings to mind features of a human upper body. ERA consists of two wrists, two limbs, two end effectors and one elbow joint together with electronics and cameras.
ERA is functionally symmetrical. Both ends act as either a ‘hand’ for the robot, or the base from which it can operate. After arm relocation on the Station, the wrist can change into a shoulder and vice versa.
Its seven rotational joints – roll, yaw and pitch joints – provide a larger range of motion than a human arm. The robot can walk end-over-end grappling standard fixtures of the Russian segment in an inchworm-like movement.
The limbs are designed for efficiency. A carbon-fibre-wound tube is used to minimize mass and has titanium fittings bonded onto it. Strength and flexibility are key for this spacewalker.
The arm that sees
Figure 4: It is crucial for the robot to know where to go. ERA uses four infrared cameras to find its way around the Space Station and to inspect its external surfaces. The images enable ERA to move from one working area to another and smoothly approach a grapple fixture. Cameras become vital in proximity operations such as attaching to base points or fetching payloads. Each camera offers a different field of view: the cameras on the ends give close-up footage, while those on the limbs provide a bird’s eye view of the scene. All of the camera optics have a fixed focal length, and are supported by lighting units (image credit: ESA)
The central control computer is embedded next to the elbow and interfaces with other parts of the arm. This ‘brain’ runs automated sequences under the supervision of a human operator. These commands allow astronauts to closely supervise ERA’s tasks and actions.
ERA is able to rethink its movements. During arm motion, several control loops add layers of safety. Proximity sensors and real-time collision avoidance algorithms compensate for misalignments as the arm approaches the target. Torque and force sensors also provide a sense of touch that prevents errors during payload pick-up and insertion.
Figure 5: The ends of the robot are at the center of the action. These mechanisms are used for either grappling payloads and moving them to different locations, or for attaching ERA to one of the multiple base points on the external surface of the Station.- ERA offers mechanical actuation to a payload using a built-in motorized screwdriver with programmable torsion and rotational speed. The arm is capable of carrying out hands-on operations with maximum safety. All functions have a mechanical override, which is available to crew members if necessary (image credit: ESA)
A True Robot -When humans and machines team up
Human and robot will work shoulder-to-shoulder in space. Astronauts will find in ERA a most valuable ally – it will save crew members precious time and free them to do other work in space.
Human–machine interfaces are the essential connections that allow the crew to control the robotic arm in orbit. Designed and tested by space experts, including astronauts, these interfaces reduce the preparation time for a spacewalk and will allow ERA to work alongside astronauts.
The crew can control ERA from both inside and outside the Space Station, a feature that no other robotic arm has offered before.
From inside: Using a laptop, the crew will have full control over ERA from inside the Space Station. Operators will see real-time models of the robotic arm and its surroundings on the screen.
Figure 6: From outside: A spacesuit-friendly control panel will allow astronauts to operate the arm during spacewalks. The size of a briefcase, the panel has been specially designed to withstand the harsh space environment and allow astronauts to control ERA even with gloved hands of a spacesuit (free of sharp edges to prevent suit punctures), image credit: ESA
• July 6, 2021: ERA (European Robotic Arm) of ESA will be launched to the International Space Station together with the Russian Multipurpose Laboratory Module, called ‘Nauka’.
Figure 7: ERA is the first robot able to ‘walk’ around the Russian segment of the Space Station. It has the ability to anchor itself to the Station and move back and forward by itself, hand-over-hand between fixed base-points. This 11meter intelligent space robot will serve as main manipulator on the Russian part of the Space Station, assisting the astronauts during spacewalks. The robot arm can help install, deploy and replace elements in outer space. ERA is 100% made-in-Europe. A consortium of European companies led by Airbus Defence and Space Netherlands designed and assembled it for ESA. - The robotic arm is largely funded by the Dutch government (video credit: ESA)
• June 23, 2021: The European Robotic Arm is the first robot that can ‘walk’ around the Russian part of the International Space Station. 4)
- The European Robotic Arm is the first robot that can ‘walk’ around the Russian part of the International Space Station. ERA has a length of over 11 m, and can anchor itself to the Station in multiple locations, moving backwards and forwards around the Russian segment with a large range of motion. Its home base will be the Multipurpose Laboratory Module, called ‘Nauka’.
- Astronauts will find in the European Robotic Arm a most valuable ally – it will save them precious time to do other work in space.
- The crew in space can control ERA from both inside and outside the Space Station, a feature that no other robotic arm has offered before.
- 100% made-in-Europe, this intelligent robotic arm consists of two end effectors, two wrists, two limbs and one elbow joint together with electronics and cameras. Both ends act as either a 'hand' for the robot.
Figure 8: European Robotic Arm specifications (image credit: ESA) 5)
Figure 9: ERA during installation on top of the the Russian Multipurpose Laboratory Module at the Baikonur Cosmodrome, in Kazakhstan, in May 2021 (image credit: RSC Energia) 6)
• May 20, 2021: ERA, designed by Fokker Space, is a robotic arm planned to be attached to the Russian Segment of the International Space Station during 2021. As the main Robotic arm of the Russian segment of the International Space Station, it will provide installation and removal of target loads on the surface of the station and monitoring of the state of the external surface of the station, as well as remotely controlled movement of astronauts in a portable workplace during spacewalks. 7)
- In accordance with the schedule of work during the installation of the ERA on the locking units, high-precision control of the position of the manipulator in the folded configuration and comprehensive tests of the fixing tools on the module housing were carried out.
- Further work on the technical complex will be carried out by specialists of RSC Energia and the Yuzhny Space Center (branch of the Center for Operation of Ground Space Infrastructure Objects, part of Roscosmos) as part of the regular preparation for launch. During this period, it is planned to install solar panels, place the delivered goods and weigh the module, assemble the space head, refuel the module tanks with fuel components and the overall assembly of the Proton-M space rocket.
- The "Nauka" (Russian for 'science') multipurpose laboratory module, developed by RSC Energia in cooperation with the Khrunichev State Research and Production Space Center, is a component of the International Space Station (ISS) that is expected to expand the functionality of the Russian segment of the ISS.
Launch: On 21 July 2021, the European Robotic Arm (ERA) is on its way to the International Space Station after being launched on a Proton rocket from the Baikonur Cosmodrome, in Kazakhstan, at 16:58 CEST (14:58 UTC) today.- The 11-m-long robot is travelling folded and attached to what will be its home base – the Russian MLM (Multipurpose Laboratory Module), also called ‘Nauka’, a 20 ton module. The Proton-M booster placed Nauka and ERA into orbit around 10 minutes after liftoff, nearly 200 km above Earth. 8)
Figure 10: The European Robotic Arm (ERA) is on its way to the International Space Station after being launched on a Proton rocket from the Baikonur Cosmodrome, in Kazakhstan (video credit: ESA/Roscosmos) 9)
Figure 11: Following launch, it will take Nauka about a week to slowly raise its orbit and catch up to the Space Station. On arrival, the Russian module will dock automatically with its own engines to Zvezda. Nauka, Zarya and Zvezda are the only three modules on the Station that can provide maneuvering capability (image credit: ESA)
This arm was made for walking
The ISS already has two robotic arms; Canadian and Japanese robots play a crucial role in berthing spacecraft and transferring payloads and astronauts. However, neither arm can reach the Russian segment.
Figure 12: It is much like a human arm. It has an elbow, shoulders and even wrists. The European Robotic Arm (ERA) will serve as main manipulator on the Russian part of the Space Station. Its seven joints can handle multi-ton payloads with a large range of motion for assembly tasks. Light yet powerful, the orbital arm has the ability to anchor itself to the Station and move back and forward by itself, hand-over-hand between fixed base-points. This space robot looks like a pair of compasses and has a length of over 11 m. When stretched, it could pass a football from a penalty spot to the goalkeeper (image credit: ESA)
ERA is the first robot capable of ‘walking’ around the Russian parts of the orbital complex. It can handle components up to 8000 kg with 5 mm precision, and it will transport astronauts from one working site to another.
“Moving hand-over-hand around the Russian parts of the Station, the European Robotic Arm will bring more freedom, more flexibility and more skills to space operations,” says ESA Director of Human and Robotic Exploration David Parker.
“We are giving the Space Station a mid-life upgrade after 20 years in orbit through our Columbus 2030 program – an opportunity to modernize space with a commercial approach,” he adds.
The launch and installation of the European Robotic Arm is a first for Europe and Russia in space. A consortium of 22 European companies from seven countries built the robot for ESA. The long-awaited premiere of this European-made robot follows 14 years of perseverance.
Figure 13: ERA will provide access to the exterior of the Russian segment and support future spacewalks. ESA ERA project manager Philippe Schoonejans shares more about this dexterous 11 m long robot from the Baikonur Cosmodrome, what it enables, and its journey from Europe to space in a tale of international partnership and perseverance (ESA/Roscosmos) 10)
Arrival to the space home
It will take Nauka eight days to slowly raise its orbit and catch up with the Space Station. On 29 July at 15:26 CEST, the new module will use its engines to dock automatically to Zvezda at the heart of the Russian segment.
ESA astronaut Thomas Pesquet will welcome the robot arm and assist in setting it up. Five spacewalks are planned to get ERA ready and perform its first space operations, some of which will be carried out by ESA astronauts Matthias Maurer and Samantha Cristoforetti.
The crew can control ERA from both inside and outside the Space Station, a feature that no other robotic arm offers.
Figure 14: ESA astronaut Samantha Cristoforetti trains with the European Robotic Arm (ERA) simulator at the Gagarin Cosmonaut Training Center (GCTC) in Moscow, Russia. It will take five spacewalks to get the robotic arm fit for space operations. ESA astronauts Matthias Maurer and Samantha Cristoforetti will support the installation both from inside and outside the Station by taking part in a few spacewalks. ERA’s first tasks in orbit are to set up the airlock and install a large radiator for the Multipurpose Laboratory Module, also called ‘Nauka’ (image credit: GCTC)
Team effort for the future
Together with the international partners, Europe is preparing to extend the life of the Space Station for years to come.
“Our home in space is constantly being improved. Europe’s Columbus lab is getting new science racks, ultra-fast data connections and external and internal platforms, commercially provided, for more users. ESA astronaut Thomas Pesquet has even been helping to upgrade the Station’s power with new solar arrays,” points out David Parker.
The symbolic European-Russian handshake in space will help demonstrate autonomous and real-time telerobotic operations, key for future missions to the Moon and Mars.
Figure 15: Infographic of ISS modules and structures after Nauka arrives and is properly installed at the station - along with the location of the European Robotic Arm on the International Space Station (image credit: ESA) 11)
1) ”European Robotic Arm,” ESA, International Space Station, 17 April 2014, URL: https://www.esa.int/Our_Activities/Human_and_Robotic_Exploration
2) ”External control interface for European Robotic Arm,” ESA, 18 September 2019, URL: http://www.esa.int/spaceinimages/Images/2019/
3) ”ERA (European Robotic Arm), the International Space Stations's latest Upgrade,” ERA brochure, 2021, URL: https://esamultimedia.esa.int/docs/science/ERA_brochure_EN.pdf
4) ”European Robotic Arm installation on Nauka,” ESA Science & Exploration, 23 June 2021, URL: https://www.esa.int/About_Us/Week_in_images/Week_in_images_21_-_25_June_2021
5) ”European Robotic Arm specs,” ESA Science & Exploration, 23 June 2021, URL: https://www.esa.int/Science_Exploration/Human_and_Robotic_Exploration
6) ”European Robotic Arm installation on Nauka,” ESA Science & Exploration, 23 June 2021, URL: https://www.esa.int/Science_Exploration/Human_and_Robotic_Exploration
7) ”European Robotic Arm Installed on the Nauka MLM,” Russia News, Space, 20 May 2021, URL: https://dfnc.ru/en/kosmos/european-robotic-arm-installed-on-the-nauka-mlm/
8) ”European Robotic Arm is launched into space,” ESA Science& Exploration, 21 July 2021, URL: https://www.esa.int/Science_Exploration/Human_and_Robotic_Exploration
9) ”ERA launch replay,” ESA Science & Exploration, 21 July 2021, URL: https://www.esa.int/ESA_Multimedia/Videos/2021/07/ERA_launch_replay
10) ”A new arm for space,” ESA Science & Exploration, 21 July 2021, URL: https://www.esa.int/Science_Exploration/Human_and_Robotic_Exploration
11) ”European Robotic Arm on the Space Station,” ESA Science & Exploration, 24 June 2021, URL: https://www.esa.int/Science_Exploration/Human_and_Robotic_Exploration
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 (firstname.lastname@example.org).