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ATV - Europe's supply vehicle for the International Space Station

Berlin, ILA 2006, 17 May 2006

EADS SPACE Transportation has been developing the unmanned space vehicle under contract to the European Space Agency ESA. After completion of integration of the first flight unit “Jules Verne”, the first mission is scheduled for 2007. ATV is one of the largest and technologically most challenging space vehicles ever developed and built in European co-operation. For the first time in European history, the ATV -launched by Ariane 5- will perform an automatic rendezvous and docking manoeuvre in space.

ATV mission

On a typical mission, ATV will carry supplies such as drinking water, propellants, foodstuffs and experiment equipment to the space station. After unloading, the space vehicle will be loaded with waste from the space station and will burn up in a controlled mode during re-entry into the Earth's atmosphere. In addition, ATV will perform an important task as far as station safety is concerned. Due to the presence of a residual atmosphere at an altitude of 400 kilometres and the large surface area of the space station, the station descends permanently and needs to be re-boosted in regular intervals. To this end, ATV has four tonnes of propellant available to lift up the space station by up to 30 kilometres. The US Space Shuttle and the Russian Progress capsule can also perform this task. With the ATV, Europe will make an essential contribution to station safety in the future.

ATV design and the flexible transportation capacity of the system
ATV has a maximum payload capacity of about 9.5 tonnes. Depending on the individual mission, this payload capacity can be used as follows: Between 1.5 and 5.5 tonnes of supply items (foodstuffs, scientific experiments, tools, etc.), up to 840 kilograms of drinking water, up to 100 kilograms of gas (air, oxygen, nitrogen, individually or in combination of two or three gases), up to four tonnes of propellant to lift up the station and up to 860 kilograms of propellant to be used for self-stabilisation of the station. The ATV system has a length of about ten metres and a diameter of 4.5 metres. ATV consists of the cylindrical spacecraft (avionics and propulsion module) and the Integrated Cargo Carrier, ICC (payload module).

The ATV spacecraft comprises the propulsion module, the avionics module including onboard computers and electronic systems, and the Ariane 5 adapter. Four solar arrays having a span of about 22 metres primarily ensure energy supply during the docking phase. During the six-month ATV mission, the solar panels can deliver about 4,000 Watt which corresponds to the consumption of a household of four on Earth within a period of three years.

The spacecraft's propulsion system comprises four 490-Newton main engines and 28 220-Newton thrusters. Flight control is carried out by the ATV software installed on a fault-tolerant computer developed in Bremen, Germany. The computer system consists of three autonomous units with self-correcting features. In addition to the engines and the control system, the avionics and propulsion module accommodates eight titanium tanks that can hold up to seven tonnes of propellant, MMH and nitrogenperoxide.

The pressurised ICC "load compartment" is used for carrying foodstuffs and experiment units for instance. It can also accommodate up to six completely equipped experiment racks to be integrated into and operated aboard the individual station modules. Another ICC section is containing water tanks, air, oxygen and nitrogen tanks and the fuelling system for propellant transfer to the space station.

Comprehensive system testing required

Integration of the first ATV flight unit started in November 2002 under the leadership of EADS SPACE Transportation in Bremen. All integration, testing and logistic activities are consolidated at the Bremen site. The individual ATV components underwent numerous system tests. Final integration of the spacecraft - connection of electronic control unit and propulsion system - as well as electronic testing of the overall system to prove the unit's "airworthiness" completed the test phase in Bremen successfully. Spacecraft and ICC were connected with each other in order to directly control the docking system or the engines by means of the onboard computers.

In July 2004, ATV were carried onboard the Airbus transport aircraft “Beluga” and then by ship and low loader to the ESA/ESTEC test centre in Noordwijk, Netherlands. Special tests have been performed here to prove ATV's resistance to launching and space-specific constraints (electromagnetic compatibility of all systems, hardware-software compatibility). These tests have been followed by acoustic and thermal impact tests in a vacuum in order to be able to precisely simulate microgravity conditions. In addition, the ICC cargo module will undergo load testing under extreme conditions.

An engineering highlight will be the mechanical testing of the solar arrays. During the tests, correct deployment and proper functioning of the solar wings having a total length of almost nine metres will be checked for the first time.

Transportation across the Atlantic Ocean

Testing at the Dutch ESA site is scheduled for completion end of 2006 to then deliver ATV on Arianespace's special vessel from Rotterdam to the European spaceport in Kourou, French Guiana. Despite its large storage area of 1,700 m², this so-called roll-off vessel, which is similar to a ferry, does not draw deep. Shallow draught is an important feature, as the vessel has to navigate a river in Kourou to discharge its cargo near the spaceport. Transportation of the ATV containers to Rotterdam is by using various inland waterways because bulk transport by road is not permitted in the Netherlands.

First mission in 2007: Flight to the International Space Station

An Ariane 5 version, featuring a storable propellant upper stage (EPS) and allowing up to five re-ignitions (Ariane 5 G+) will be used for the first ATV mission.

It will be the main task of the Ariane 5 to inject ATV into an orbit inclined by 51,6° to the Equator. This orbit exactly corresponds to the ISS orbit. As a side effect, this inclination will allow monitoring of both ATV on its mission and the ISS in regular intervals from Bremen as the city has a similar latitude.

Ariane 5 is a two-stage launch system. It consists of a main stage with two boosters and an upper stage with integrated payload. About seven minutes after lift-off the main stage separates, leaving ATV attached to the upper stage. After a good 60 minutes the upper stage injects ATV into orbit at an altitude of about 300 kilometres.

Immediately after separation from the Ariane upper stage, engines and all onboard systems, such as the navigation and control system, will be activated. The solar panels will be deployed. With its solar panels following the sun, ATV will then activate its communication antennas and carry out a so-called "health test" in order to ensure proper functioning of all systems. Then the space vehicle will proceed to the International Space Station.

Docking to the ISS

The safety of the crew and the station is the number one priority when automatically docking to the ISS. During the flight, the ATV's onboard systems are permanently monitored by the ISS Ground Control Centre in Houston, Texas/USA, and by the ATV Control Centre in Toulouse, France. The final approach phase is monitored by the Russian control centre in Moscow because of the fact that ATV docks to the Russian station module "Zvezda". The autonomous, intelligent ATV safety system ensures that in case of even the slightest system anomaly the space vehicle automatically returns to its last position and "parks" in an appropriate distance to the ISS. After checking the system, a new approach is started.

At a distance of almost 30 kilometres to the ISS, the fully automatic docking phase begins. ATV enters into direct radio contact with the space station. A GPS determines the exact position of the vehicle to precisely bring it to the ISS orbits. At a distance of 3,500 metres mission continuation must be authorised by the control stations involved to allow ATV to continue its approach.

At a distance of 250 metres, the docking system and its sensors establish direct contact with the ISS. In addition to the already existing radio connection, the astronauts onboard the ISS can directly monitor the docking manoeuvre by video now. The ATV's laser distance measuring unit verifies the data transmitted by the GPS. After authorisation by the ISS and the ground control stations, ATV continues its approach to 12 metres and covers the last few metres to the ISS docking port at a relative speed of a few centimetres per second. The ATV's extended tip having a diameter of about 15 centimetres must be captured by the docking port of the Russian "Zvezda" module having a diameter of almost 90 centimetres.

As soon as the ATV docking system touches the space station for the first time, ATV provides a short, final thrust to ensure the European space vehicle's capture by the Russian module's docking port. ATV aligns to the longitudinal axis of the ISS. All the electrical, mechanical and fluid connections between the ISS and the space vehicle are set up automatically. After shutdown of all the docking systems and placing ATV in the so-called dormant mode, the astronauts remove the complete docking system from the vehicle. A cargo hatch with a diameter of almost one metre connects the ICC with the Russian service module and makes the European space vehicle an integral part of the ISS.

Competence of the European space industry

ATV is one of the largest and technically most challenging space vehicles ever developed and built in Europe. Within the scope of Europe's participation in the International Space Station, the European Space Agency ESA awarded EADS SPACE Transportation a contract to develop and build the ATV space vehicle. EADS SPACE Transportation with its competence centres in Bremen, Lampoldshausen and Les Mureaux near Paris has the know-how required to develop, build and test such a large system.

The specific know-how of EADS SPACE Transportation covers many aspects: First, EADS SPACE Transportation is able to manage development and production of such a technologically complex and challenging space vehicle as prime contractor. Secondly, EADS SPACE Transportation co-ordinates the activities of 30 partner companies in ten European countries and further companies in Russia and the United States, supplying parts, components and subsystems for ATV. EADS SPACE Transportation must ensure that all components are delivered in the right quality at the agreed price to the right place in the right time. Thirdly, EADS SPACE Transportation builds the propulsion system and the control unit in its facilities in Bremen and develops and programmes the flight software and the software required for fully automatic vehicle docking to the station in its facilities in Les Mureaux near Paris. In the past few years, Europe had to work hard for gaining the know-how required for the project, a know-how that had only be available within Russian and US space projects so far.

Within the industry consortium, members of which are among others Alcatel Alenia Space (Italy), Contraves (Switzerland) and Dutch Space (Netherlands), about 1,600 technicians and engineers throughout Europe are dealing with ATV development. EADS SPACE Transportation as ATV system leader is involved in the project through its sites in France and Germany.

EADS SPACE TRANSPORTATION
EADS SPACE Transportation is the European specialist for access to space and manned space activities. It develops and produces Ariane launchers, the Columbus laboratory and the ATV cargo carrier for the International Space Station, atmospheric re-entry vehicles, missile systems for France's deterrent force, propulsion systems and space equipment.

EADS SPACE Transportation is a wholly owned subsidiary of EADS SPACE, which is dedicated to providing civil and defence space systems. In 2005, EADS SPACE had a turnover of €2.7 billion and 11,000 employees in France, Germany, the United Kingdom and Spain.
EADS is a global leader in aerospace, defence and related services.
In 2005, EADS generated revenues of €34.2 billion and employed a workforce of more than 113,000.

Contacts for the Media
Rémi ROLAND
EADS SPACE
(FR)
Tel.: +33 (0) 1 42 24 27 34

Jeremy CLOSE
EADS SPACE
(UK)
Tel.: +44 (0) 1 438 77 3872

Mathias PIKELJ
EADS SPACE
(GER)
Tel.: +49 (0) 7545 8 91 23