The European Robotic Arm (ERA) is a robotic arm that is attached to
the Russian Orbital Segment (ROS) of the International Space Station. Launched to the ISS in July 2021; it is the first robotic arm that is able to work on the Russian Segment of the station. The arm supplements the two Russian Strela cargo cranes that were originally installed on the Pirs module, but were later moved to the docking compartment Poisk and Zarya module.
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 and ERA's Portable Workpost was launched preemptively, attached to Rassvet or Mini Research Module 1(MRM-1). The Nauka Module and Prichal module 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.
Technical characteristics
The European Robotic arm consists of two 'limbs' that are symmetrical sections made primarily of carbon fibre reinforced plastic, and are approximately 5 m (16 ft) long. At either end of the arm are identical gripper mechanisms called End Effectors (EES), which the arm uses to hold onto the station, grab onto payloads, and to assist in EVA activities.
On average the arm uses 475 watts of power to operate while having a peak operational power consumption of 800 watts. When on standby the arm only consumes 420 watts, and 250 watts while in hibernation.
Located with in the ECC's RISC subsystem is the ERA's main central processing unit (CPU). The main CPU is a Temic designed ERC32 with 10 MHz clock, addressing 1.5 megabytes (Mb) of memory, as well as 32 kilobytes (Kb) of ROM. In addition to being able to be controlled from the station, ground operators can control the arm, as well.
EVA control
Control from outside the space station uses a specially designed interface that can be controlled while in a spacesuit known as the Extra Vehicular Activity-Man Machine Interface (EVA-MMI or EMMI). The EVA-MII has 16 LED displays of eight characters each; displaying essential status data, command verification data and emergency caution and warning messages. It also provides redundancy for critical status data through redundant LEDs.
After the decision to cancel the Hermes program, ESA and the Russian Space Agency, in 1992, agreed to use the HERA technology to service the Mir-2 Space Station. The name was then changed to the European Robotic Arm (ERA). It was here that a control computer was added to the arm's design, as well as two new operational consoles were designed, one for a cosmonaut in EVA, and one for a cosmonaut inside the station. Following the cancellation of the Research Module ERA was moved to the Russian Science Power Platform, which would have become the base of operations for the arm. Its first mission after being relocated to its storage position would have been to install part of the solar array system.
With the change to a shuttle launch, two major changes to the ERA design were made in 1997. The first being that the joints were altered to facilitate launch on the Space Shuttle. Secondly the ERA on-board computers were switched to being based on the ESA's Data Management System. That same year also saw evaluation and review of the Man Machine Interfaces for ERA start. The inclusion of ISS astronauts and cosmonauts along with experts led to several design improvements. Manufacturing and testing of ERA engineering models also started in 1997. The electrical interface model was shipped to Russia to verify electrical interfaces between the ERA systems and elements of the Russian segment of the ISS.
Training of instructors was complete in 2005 with two training courses being held at ESTEC with nine Russian instructors receiving certification the following year after a refresher training course in June 2006.
In February and March 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.
thumb|ERA spare elbow on MRM-1 below the Russian flag and Energia symbol covered under thermal blankets
Following technical issues, the launch was delayed from 2007 to 2012. In 2010, the Space Shuttle Atlantis delivered Rassvet (Mini Research Module 1) on STS-132, (as a part of an agreement with NASA) to the station, which included a spare elbow joint with 2 limbs to allow the actual to repair itself while in orbit and the Portable Work Platform for the ERA, which will be used during EVAs. Further delays resulted in the ERA launch being delayed to 2014.
left|thumb|MLM outfittings on MRM-1 including the black ERA portable workpost on the left near the docking port
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 with Nauka resulted in the launch being delayed several more times until January 2021. Due to concerns over the novel coronavirus, work on the Proton rocket and Nauka was delayed, which resulted in the launch being delayed to May 2021.
In May 2020 the ERA was shipped to Baikonur for final processing. On 20 May 2021 the arm was attached to the hull of the Nauka module.
The ERA was launched on 21 July 2021 atop a Proton rocket alongside the Nauka module, 20 years 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.
Launch configuration
thumb|The flight model of the European Robotic Arm well on display during a media day at Airbus Defence and Space Netherlands on 5 April 2006. During the day, the flight model was set up in a similar configuration to how it would be configured for launch.
During launch the ERA was located in a launch position on Nauka, referred to as the "Charlie Chaplin" configuration. During launch, both of the end effectors were grappled on to a special base point, each acting as a load suspension system. The arm was also attached to Nauka by the means of six launch fixation mechanisms. Each mechanism consisted of one or two hooks that tied down the ERA to its mounting seat, during future EVA's these hooks will be released allowing for ERA to start to prepare for operations. These attachment points are located at the elbow joint, the wrist electronic boxes and the roll joints.
ERA validation operations and deployment
The assembly and Validation of the European Robotic Arm will be conducted in five different stages. The first part was the connecting and testing of ERA and its control interfaces, as well as conducting an initial check of the arm. This was performed on 22 September 2021 when ESA astronaut and Flight Engineer Thomas Pesquet, worked with Roscosmos cosmonaut and Flight Engineer Pyotr Dubrov in Nauka to configure the ERA controller hardware and software. During testing the ERA laptop, external control panel and the Russian control computer were shown to being working well, and able to communicate with each other but initial tests showed glitches in data transmission between Zvezda and Nauka which could cause delays to ERA deployment. Communication links between the ISS, Russian Mission Control Centre, and the European Robotic Arm Support center in the Netherlands were successfully tested. Initial checks also included the validation of the external Man Machine Interface and that the ERA can communicate properly while connected to a base point located on the outside of the ISS. To validate the MMI an EVA was required.
left|thumb|347x347px|The European robotic arm is pictured extending out from the Nauka multipurpose laboratory module during a mobility test several days after Roscosmos cosmonauts Oleg Artemyev and Denis Matveev activated the ERA during a seven-hour and 42-minute spacewalk.
The second stage included the installation and validation of the ERA's transfer capabilities. During this stage both the internal and external MMI were evaluated. During an EVA an astronaut will remove the launch restraints keeping the ERA in its launch configuration as well as remove the remainder of launch covers. On 28 April 2022, the second of the series of space walks occurred, during which Artemyev and Martveev unstowed the arm from its launch position by releasing actuators enabling the arm's grip, freed additional launch locks, as well as installed handrails to ease working on and around the device. Following this the ERA was extended and commanded to attach to existing interfaces on Nauka, and moved to the forward-facing side of the module. During the EVA the arm was controlled by Sergey Korsakov. A third EVA in the series was scheduled to occur in mid-May and was performed by Oleg Artemyev and Samantha Cristoforetti.
On June 22, 2022, an attempt to connect to the BTL-3 grapple fixture was successful and perform the base command and control was changed to ERA EE1 from EE2 on BTL-2 fixtures.
During this stage, EVA cameras were installed by an astronaut, which are located on the wrist and elbow joint of the ERA. Following the completion of the EVAs needed on the ERA, joint tests were carried out, followed by multiple joint tests. Following the completion of these tests, the ERA was relocated by grappling base points on the surface of the ISS and was checked by being commanded to grapple and relocate the Portable Work Platform. The portable work platform launched with the spare elbow joint on MRM-1 in 2010 can attach to the end of the ERA to allow cosmonauts to ride on the end of the arm during spacewalks. Upon completion the ERA was placed in hibernation mode.
Mission Preparation and Training Equipment
Mission Preparation and Training Equipment (MPTE) are tools and facilities developed by National Aerospace Laboratory - NLR, used in the training of astronauts and operators, supporting maintenance, as well as aiding in missions. Three identical versions of the MPTE were installed at Rocket-Space Corporation Energia RSC/E, the Russian Mission Control Centre for the ISS, the Gagarin Cosmonaut Training Center (GCTC), as well as the European Space Research and Technology Centre (ESTEC). Both the arm and the MPTE had to be designed to be able to function and operate for a minimum of 10 years.
In February and March 2006, the MPTE was delivered to several locations in Russia. Due to the delays in the launch, much of the hardware in the computer systems had surpassed its expected life span. As a result, it had become hard to maintain the computers in the MPTE as spare parts were becoming obsolete, and hard to find. As well the ERA software maintenance facility underwent a complete upgrade to the latest software development tools at the time. The ERA simulator includes the reuse of existing software that was created to aid in the development of the arm itself, such as the ERA Simulator Facility, as well as existing software such as the Image Generation Subsystem of EuroSim.
An additional arm is fixed on the Japanese Experiment Module, the Remote Manipulator System (JEM-RMS), also known as Kibō. The arm was added to the station during STS-124. The arm uses a similar PDGF grapple fixture to Canadarm2, but is primarily used to service the JEM Exposed Facility.
Because all Russian and European spacecraft dock automatically there is no need to manipulate spacecraft on the Russian segment so it is not necessary for ERA to be as large or handle as large of loads as Canadarm2. 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 The ERA is less powerful and smaller than the Canadarm2 as it is 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 in length, shorter than the Canadarm2 which is in length. The ERA is also lighter by , with the arm being as opposed to the Canadarm2's 1,800 kg (4,000 lb). The maximum payload mass of the ERA is , as opposed to the Canadarm2's maximum payload mass at 116,000 kg (256,000 lb).