DUTCH CONTRIBUTION TO INTERNATION SPACE STATION IN FINAL STAGES

Fokker Space started the ERA project in 1985. Back then it was called HERA (HErmes Robot Arm) the robot arm for the proposed European Space Shuttle HERMES. When HERMES was cancelled, Fokker and RSC-Energia of Russia began talking for use of the robot arm on the successor for the MIR Space Station, MIR-2. Studies were being conducted to make the work for the cosmonauts who would work outside the Space Station easier, cheaper and less time consuming.

In 1993 when Russia joined the United States in the International Space Station program, talks between Europe and Russia on the use of the robot arm on ISS were held. In July 1996 an agreement was reached for use of the arm on the Russian Science Power Platform of the Space Station.

The European Space Agency has given Fokker Space the prime contract for building and testing of ERA. Several other European companies are also contributing to ERA. The Russian Space Agency RKA gave the Russian side of the contract to RSC-Energia so the partners that held the first studies would remain the same.

The ERA arm will be 11.3 meters in length and its weight will be around 630 kg. The symmetrical arm will consist of seven joints (roll, yaw, pitch, pitch, pitch, yaw and roll). On each end of ERA, there will be an “End-Effector”, so one end can be either the base or the “grip” of the arm. This unique design allows ERA to move along the station using special fixed points, located on the station surface. While "base" of the manipulator is attached to the one point, its "grip" goes to the nearest point. After fixing of the "grip" at this point, manipulator releases its "base" - it becomes "grip" - and moves the "grip" to the next point.

Six of the seven joints can operate independent from each other making it as flexible as possible. The service area of the arm will be a sphere with a 9.09 m radius, operating at a maximum speed of 20 cm/sec and a minimum speed of 1 mm/sec. The “brain” of ERA will be located on the arm itself, making communications to ERA simpler. There are two control interfaces for ERA, one is located inside the Zvezda module (this will be a normal laptop computer) and the other is located outside the station, thus making it easier for operation by a space walking crew.

ERA’s first tasks once it is placed on ISS will be helping in the assembly of the solar arrays of the SPP. ERA will grapple a folded solar array out of the Shuttles cargobay, then it will move the solar array to its destined location on the SPP, installs it and enables the deployment of the solar array using the ERA built-in "screw-driver", the Integrated Service Tool (IST). Other tasks for ERA will be;

The replacement of solar arrays, radiators and thrusters at the end of their lifetimes.
The replacement of Orbit Replaceable Units (ORU),
Inspection of the outer side of the space station via one of its cameras, in order to verify the integrity of ISS structure and the proper functioning of externally mounted systems and mechanisms.

Four versions of ERA were built by Fokker. Two of those were shipped to Russia for

training use, one model, the Weightless Environmental Test-model (WET) will be used

by the cosmonauts at the Gagarin Cosmonaut Training Centre. The other, the

Geometric Model, went to RSC-Energia for physical configuration tests.

The two ERA development models where tested in the Netherlands at ESA’s ESTEC

facility in Noordwijk and at the Fokker factory in Leiden. One of those, the Engineering

and Qualification Model (EQM) was used for vacuum and radiation tests in November

1999 in the Large Space Simulator at ESTEC. The last is the actual flight model. That

model is currently undergoing vibration test at ESTEC to make sure it is strong enough for

handling equipment up to 8000 kg, and that it can withstand a shuttle launch. The flight model will be shipped to Russia in 2001 and there it will be integrated with the SPP and readied for launch.

Thanks to: Heidi Graf of ESTEC Public relations.