European Robotic Arm
European Robotic Arm Mission Launch Logo
Module statistics
Part ofInternational Space Station
Launch date21 July 2021, 14:58:25 UTC
Launch vehicleProton-M
Docked29 July 2021, 13:29:01 UTC
Mass630 kilograms (1,390 lb)
Length11.3 metres (37 ft)

Rendering of European Robotic Arm on Nauka Module

The European Robotic Arm (ERA) is a robotic arm that is attached to the Russian Orbital Segment (ROS) of the International Space Station. The arm was launched to the ISS on 21 July 2021, 14:58 UTC on a Proton-M Rocket, attached to the Nauka module, and docked with the station on 29 July 2021, 13:29 UTC. It is the first robotic arm that is able to work on the Russian Orbital Segment of the station, and replaces the two Russian Strela cargo cranes that were installed on the Pirs module, but were moved to the docking compartment Poisk[1] and Zarya module[2]

The ERA was developed for the European Space Agency (ESA) by a number of European space companies. Airbus Defence and Space Netherlands (formerly Dutch Space) designed and assembled the arm and was the prime contractor; it worked along with subcontractors in 8 countries. In 2010, a spare elbow joint for the arm was launched preemptively, attached to the Mini-Research Module 1 (MRM-1). The Multipurpose Laboratory Module will serves as home base for ERA; originally, the arm was going to be attached to the canceled Russian Research Module and later to the also canceled Science Power Platform.[3]

Design and Capabilities


The European Robotic arm consists of two 'limbs' which are symmetrical arm sections made of carbon fibre reinforced plastic, approximately 5 metres (16 ft) long.[4] Two identical gripper mechanisms called End Effectors (EES), with one located on each end, and are used by the arm to hold onto the station, grab onto payloads, and to assist in EVA activities.[5] In total there are seven motorized joints, three are located at each of the wrists, and allow for roll, yaw, and pitch movements. The elbow consists of one motorized joint, which is limited to pitch movements.[6] The arm is controlled by the ERA Control Computer (ECC), or On board Computer (OBC) which is located towards the elbow.

When fully extended the arm has a total length of 11.3 metres (37 ft), and can reach 9.7 metres (32 ft) and has 7 degrees of freedom.[7] It has a mass of 630 kilograms (1,390 lb) and can hold a total payload mass of 8,000 kilograms (18,000 lb).[8] The arms tip can reach a speed of 0.1 metres per second (0.33 ft/s) and and has an accuracy of 5 millimetres (0.20 in). The European Robotics Arm itself was designed to be serviceable and allow for the exchange of large parts via EVA in case of failure or an emergency situation. There parts are called EVA Replaceable Units (ERUs), also referred to as Orbital Replacement Units (ORUs), which can all be replaced in-orbit; the ERA is composed of three ERU sections.[6]

End Effectors

File:Nauka module with ERA at the ISS!.jpg
European Robotic Arm on Nauka Module

Located at either end of the arm are the End Effector Subsystem (EES). The EES are designed to attach specifically with the base points located on the Russian segment of the station. Since the ROS uses different base points than the US Orbital Segment, the arm is unable to operate and access the other parts of the station.[7] The EES consist of two Basic End Effectors (BEE), Base Points (BP) and Grapple Fixtures (GF). Both of the End Effectors are capable of transferring data, power or mechanical actuation to payloads, as well as include a mechanical drive that can operate like a wrench tool, called the Integrated Servicing Tool (IST)[5] Located within the each of the EEs is a Camera and Lighting Unit (CLU) which aids in the control of the arm; an additional two CLUs are located on both limbs.[6]

Major Functions and Tasks

The ERA has several features. Most prominent is its ability to 'walk' around the exterior of the Russian segments of the station under its own control, moving hand-over-hand between pre-fixed basepoints, and its ability to perform many tasks automatically or semi-automatically, thereby freeing its operators to do other work. Specific tasks of the ERA include:[7]

Control and data interfaces of ERA


Astronauts can control the robot from both inside and outside the space station. Control from inside the space station (Intra Vehicular Activity-Man Machine Interface (IVA-MMI)) uses a laptop, which shows a model of the ERA and its surroundings. Control from outside the space station (Extra Vehicular Activity-Man Machine Interface (EVA-MMI)) uses a specially-designed interface that can be used while in a spacesuit.[6] The arm can also be controlled by a ground team.

Comparison with Canadarm2

The Canadarm2 is a large robotic arm on the US Orbital Segment of the station. Due to the similarities between the ERA and the Canadarm2 a comparison can be made between the two. Both arms perform Station maintenance, are able to move supplies and equipment, inspection of the station, as well as aid astronauts during space walks.[11][12] Where they differ is that the ERA is able to function completely automatically or semi-automatically, as well be directed either from inside or outside the station. The Canadarm2 has to be controlled by a human, whether that be by astronauts on board the ISS or be a ground team at the CSA headquarters or NASA[13] The ERA is less powerful and smaller than the Canadarm2 as it's not required to dock spacecraft with the station. Due to the difference between the grapple fixtures between the ROS and the USOS of the station, the Canadarm2 is only able to operate on the USOS while the ERA is only able to operate on the ROS. Both arms are able to move around from point to point, end-over-end on the station, with them being able to self-relocate.

The ERA is 11.3 metres (37 ft) in length, 6.3 metres (21 ft) shorter than the Canadarm2 which is 17.6 metres (58 ft) in length. The ERA is also lighter by 1,170 kilograms (2,580 lb), with the arm being 630 kilograms (1,390 lb) as opposed to the Canadarm2's 1,800 kg (4,000 lb). The maximum payload mass of the ERA is 8,000 kilograms (18,000 lb),[8] as opposed to the Canadarm2's maximum payload mass at 116,000 kg (256,000 lb).

European Robotic Arm Simulator

Located at the Gagarin Cosmonaut Training Center (GCTC), in Moscow, Russia, a mockup of the ERA is submerged in a large pool in the Hydrolab facility, which allows astronauts to train to operate the arm before they leave for the station. The mockup arm is attached to a mockup of the Nauka module. Here astronauts don suites designed to mimic the conditions of wearing a spacesuit, and a weightless environment. Training also includes the use of a entirely digital simulator, which mimics controlling the arm from within the station. In 2005, ESA astronaut André Kuipers and his colleague Dimitry Verba, conducted the first trial on the arm. This involved assembling the arm in the weightless environment, and was used to make recommendations of changes to the final arm, before its launch in 2021.[9]

Robotic arms at the ISS

The International Space Station already features numerous robotic arms, the first being the Canadarm2 (which can use the PDGF grapple fixtures on the US Orbital segment), but because the Russian grapple fixtures are different, that arm and Dextre can only be used on the Zarya module of the Russian segment since a PDGF was installed in 2011 during STS-134[10]. Dextre has two robotic arms, fixed to its 'body'.

The Kibo arm is fixed on the Japanese Experiment Module, the Remote Manipulator System (JEM-RMS) and uses a similar PDGF grapple fixture to Canadarm2.

Because all Russian and European spacecraft dock automatically there is no need to manipulate spacecraft on the Russian segment so the European arm is half the length and less powerful than Canadarm2.


Plans for a European Robotic Arm began in the 1980s, under the name HERA. The arm was to act as a cargo crane and for maintenance of the canceled European space shuttle called Hermes. With the cancelation of the programme, studies for a robotic arm began which looked at a robotic arm being a part of the Mir-2 space station. Following the cancelation of the Mir-2 station in favour of the International Space Station in 1993, the ERA elements were adapted to the Russian segment of the Station.[14]

European Robotic Arm (ERA) grapple/base used on the Russian segments of the ISS

In 1996, the ESA and the Russian space agency, Roscosmos, signed a cooperation agreement about the ERA, and would have the arm be a part of the canceled Russian Research Module. Development on the arm began in 1998.[15] The ERA was moved to the Russian Science Power Platform, which would have become the base of operations for the arm, and was planned to be launched in 2001[3] on a Space Shuttle, but was later delayed to 2002. It was delayed again and the launch date was uncertain following the hold on the Space Shuttle program due to the Space Shuttle Columbia disaster, as well as the cancelation of the Science Power Platform.[5]

In 2004, testing of the Weightless Environment Test model "WET" began. That same year Russia introduced the Multipurpose Laboratory Module (MLM), also called Nauka, and proposed that the ERA could be installed, launched and operated on the module. The Nauka module is not designed for launch on a Space Shuttle and instead would be launched on a Russian Proton rocket. The following year, ESA signed a contract with Airbus Defence and Space Netherlands to prepare the ERA to launch on a Proton rocket in November of 2007.[16][17]

In February of 2006, the Mission Preparation and Training Equipment for the European Robotic Arm was delivered in Russia, which would be used for training to use the arm as well as preparation for both its launch and use. Equipment was also delivered to the Russian Mission Control Centre for the ISS, and would be used for mission monitoring purposes.[18]

Following technical issues, the launch was delayed from 2007 to 2012. In 2010, as a part of STS-132, the Space Shuttle Atlantis delivered the Mini-Research Module 1 (MRM1), Rassvet, to the station, which included a spare elbow joint with 2 limbs and the Portable Work Platform for the ERA.[19][20] Further delays resulted in the ERA launch being delayed to 2014.

Due to issues in the development of the MLM module, the launch was further delayed, and the earliest it could have launched was the end of 2015. Further issues coming from the MLM module resulted in the launch being delayed several more times till January of 2021. Due to concerns over the novel coronavirus, work on the Proton rocket and MLM module was delayed, which resulted in the launched being delayed to May 2021.[21][22]

In May of 2020 the ERA was shipped to Baikonur for final processing.[23] On 20 May 2021 the arm was attached to the hull of the Nauka module.[24]

The ERA was launched on 21 July 2021 atop a Proton rocket along side the Nauka module, 20 years[25] after its originally planned launch and 35 years after it was first designed. It successfully docked and was attached to the station on 29 July 2021 at 13:29 UTC.[20][26][27]

Bringing ERA to Functionality

Externally, after the Nauka module has been connected to the ISS via a series of cables, the first order of business will be to deploy the European Robotic Arm (ERA), which launched attached to the outside of Nauka. The first spacewalk will also involve removing external covers and launch restraints, following which the ERA will be activated and fully checked out from the ground. It will now take five spacewalks to assemble and prepare the robotic arm to be fit for space operations. ESA astronauts Matthias Maurer and Samantha Cristoforetti will aid in the installation of the arm both from inside and outside the Station by taking part in spacewalks. ERA needs to be fully operational in order to proceed with the next phase of operations – which is transferring MLM outfittings that is the experiment airlock and install a radiator to Nauka along with retrieving it's boom and spare elbow joint.Upon finishing of assembly, the ERA's first tasks are to set up the airlock and install a radiator for the Nauka module.[28]

The ERA will be used to remove the radiator and airlock from MRM-1 and transfer them over to MLM – with an extension boom being required to allow ERA to reach the airlock. This process is expected to take several months. A Portable Work Platform will also be transferred over, which can attach to the end of the ERA to allow cosmonauts to "ride" on the end of the arm during spacewalks.


See also


  1. ^ February 2012, Tariq Malik 16 (2012-02-16). "2 Russian Cosmonauts Move Space Station Crane in 6-Hour Spacewalk". Retrieved 2021-07-29.((cite web)): CS1 maint: numeric names: authors list (link)
  2. ^ "Cosmonauts walk in space to move crane, deploy satellite (UPDATED) | Space News, International Space Station, Russian Space". Retrieved 2021-07-29.
  3. ^ a b Zak, Anatoly. "NEP science and power platform of the ISS". Retrieved 2 April 2019.
  4. ^ "European Robotic Arm Brochure" (PDF). European Space Agency.((cite web)): CS1 maint: url-status (link)
  5. ^ a b c H.J. Cruijssen; M. Ellenbroek; M. Henderson; H. Petersen; P. Verzijden & M. Visser (May 2014). "42nd Aerospace Mechanism Symposium: The European Robotic Arm: A High-Performance Mechanism Finally on its way to Space" (PDF). NASA. p. 319. Retrieved 29 July 2021.((cite web)): CS1 maint: url-status (link)
  6. ^ a b c d H.J. Cruijssen; M. Ellenbroek; M. Henderson; H. Petersen; P. Verzijden & M. Visser (May 2014). "42nd Aerospace Mechanism Symposium: The European Robotic Arm: A High-Performance Mechanism Finally on its way to Space" (PDF). NASA. p. 320. Retrieved 29 July 2021.((cite web)): CS1 maint: url-status (link)
  7. ^ a b c "European Robotic Arm Brochure" (PDF). European Space Agency. p. 4.((cite web)): CS1 maint: url-status (link)
  8. ^ a b H.J. Cruijssen; M. Ellenbroek; M. Henderson; H. Petersen; P. Verzijden & M. Visser (May 2014). "42nd Aerospace Mechanism Symposium: The European Robotic Arm: A High-Performance Mechanism Finally on its way to Space" (PDF). NASA. pp. 319 to 333. Retrieved 22 October 2014.
  9. ^ "Underwater trials for Europe's robotic arm". Retrieved 2021-07-29.
  10. ^ "STS 134: Final Flight of Endeavour" (PDF). NASA. Retrieved 2 April 2019.
  11. ^ Agency, Canadian Space (2018-06-15). "About Canadarm2". Retrieved 2021-07-20.
  12. ^ "European Robotic Arm". Retrieved 2021-07-20.
  13. ^ Garcia, Mark (2018-10-23). "Remote Manipulator System (Canadarm2)". NASA. Retrieved 2021-07-20.
  14. ^ "European Robotic arm" (PDF). AutoEvolutoion. 15 July 2021.((cite web)): CS1 maint: url-status (link)
  15. ^ "European Robotic Arm (ERA)". Retrieved 2021-07-20.
  16. ^ "ESA signs contract with Dutch Space to prepare the European Robotic Arm for its launch on Proton". Retrieved 2021-07-20.
  17. ^ "ESA astronaut goes underwater to test European Robotic Arm". Retrieved 2021-07-20.
  18. ^ "Step forward for ERA as training equipment arrives in Russia". Retrieved 2021-07-20.
  19. ^ "STS-132: PRCB baselines Atlantis' mission to deliver Russia's MRM-1". 2009-04-09. Retrieved 2021-07-20.
  20. ^ a b "Dutch robotic arm finally reaches into space". 2021-07-05. Retrieved 2021-07-20.
  21. ^ "Dutch ISS robot arm delayed by Russian team". NL Times. Retrieved 2021-07-20.
  22. ^ "Russia Postpones Launch of Nauka Research Module to the orbiting outpost to 2021". TASS. 2 April 2020. Retrieved 2 April 2020.
  23. ^ "European Robotic Arm arrives in Baikonur". Twitter. Retrieved 2020-06-03.
  24. ^ "Новости. Модуль «Наука» оснащен европейским манипулятором ERA" [The "Science" module is equipped with the European manipulator ERA]. Retrieved 2021-05-22.
  25. ^ "European Robotic Arm Brochure" (PDF). European Space Agency. p. 3.((cite web)): CS1 maint: url-status (link)
  26. ^ "European Robotic Arm is launched into space". Retrieved 2021-07-21.
  27. ^ @roscosmos (July 29, 2021). "According to the received telemetric information, the exact time of contact is 13:29:01 UTC" (Tweet). Retrieved 29 July 2021 – via Twitter.
  28. ^ "Samantha Cristoforetti trains with the European Robotic Arm". Retrieved 2021-07-29.