ISS ESA Automatic Transfer Vehicle (ESA)

The Automated Transfer Vehicle or ATV is a European Space Agency spacecraft designed to supply the International Space Station with propellant, water, air, payload experiments and the like. In addition, the ATV can re-boost the station, restoring its orbit that shrinks over time due to friction with the atmosphere. It is an unmanned spacecraft launched with an Ariane 5 from Kourou, French Guiana. After approximately 2 days of autonomous transfer flight it arrives at the International Space Station and docks automatically to the Russian Service Module Zvezda.

The ATV is designed at least partially as a replacement for the Progress spacecraft, though with three times its capacity. Like the Progress it carries both bulk liquids and relatively fragile freight which is stored in a cargo hold kept in a pressurized shirtsleeve environment so that astronauts can have access to it without putting on a suit. Again like the Progress, the ATV will be serving at the same time as a container for the station's waste.

Each ATV weighs 20 metric tonnes at launch and has a cargo capacity of 9 metric tonnes:

• 1500_5500 kg of dry cargo (re_supply goods, scientific payload, etc.),
• 0_840 kg of water,
• 0_100 kg of gas (Nitrogen, Oxygen, air, 2 gasses/flight),
• 0_4700 kg of propellant for the re_boost manoeuvre and refueling the Station. The ATV propellant also used for re_boost (Monomethylhydrazine fuel and Nitrogen tetroxide oxidizer) is of a different type from the payload Russian refueling propellant (UDMH fuel and N₂O₂ oxidiser).

After undocking the ATV is led to a controlled burn-up in the atmosphere, along with up to 6.5 metric tonnes of waste.

The prime contractor of the ATV is EADS SPACE Transportation, leading a consortium of many sub-contractors and the flight models are integrated in its Bremen facility.

The first ATV, whose construction is now complete, is expected to be launched by the end of 2005. It is called the Jules Verne, in memory of the first science fiction writer of modern times. Contracts and accords have been signed for six more ATVs, which should be launched about once every year.

The Japan Aerospace Exploration Agency, JAXA is currently working on a similar vehicle, the H_II Transfer Vehicle (HTV) to resupply the Kibo Japanese Experiment Module (JEM) on the ISS, as well as the rest of the station if need be. Contrary to the ATV, the HTV would berth to Node 2 of the ISS.

ATV Evolution

The European Space Agency is studying potential evolutions and adaptations of the ATV, following the decision by NASA to retire the Space Shuttle around 2010.

Most of the studies are focused on the adaptation of the ATV in order to allow cargo return to Earth's surface.

A first study is called PARES (PAyload REtrieval System), and would include a small ballistic capsule similar to VBK-Raduga and embedded into the ATV docking interface, which would bring back a few tens of kg of payload. PARES could feature a deployable heat shield system. The European Space Agency is also proposing the system for use with the Progress spacecraft and the H-II Transfer Vehicle (HTV).

The CARV (Cargo Ascent and Return Vehicle) study is investigating a larger lifting capsule, capable of bringing back a few metric tonnes of payload, which could be installed in place of the ATV pressurized cargo hold.

Such vehicles could be available by 2010.

External links

• ESA's description of the ATV (http://www.esa.int/export/SPECIALS/ATV/index.html)