Airbus Defence and Space

Welcome aboard the ISS

Docking with the International Space Station may not look all that difficult, but in fact the operation is quite tricky. Spacecraft moving at a speed of 27,000 km/hr some 400 kilometres above our heads must be slowly joined together, as the distance separating them is reduced by a few centimetres per minute.

One of the characteristics of the European space station is its ability to dock with resupply spacecraft developed with different types of technology, such as the Shuttle, HTV, Soyuz, or ATV. The Shuttle, for example, uses a different technique for docking with the ISS than Soyuz or the Japanese HTV.

There are in fact three different techniques for docking with the station: automatic, semi-automatic and manual, depending on how the spacecraft were built. Why is this? Quite simply because the different countries participating in the conquest of space have each decided to use different types of technology for historical reasons.

In the 1970s, for example, the Russians opted for computerised tools, as the assembly work for the Mir space station was already based on the same technology. The Europeans also decided to use an automatic approach procedure for their ATV, but the United States wanted to continue perfecting piloting techniques: onboard the Shuttle, it is the pilot who is behind the controls and who directs the approach. The Japanese, on the other hand, have developed a hybrid technique called "berthing": their vehicle can automatically approach the station until it is within the range of the ISS's robotic arm, which berths the HTV under the controls of an astronaut.

The current docking techniques provide the spacecraft with access to ports of different sizes, which can be very important when large pieces of equipment are being brought aboard. However, when the station reaches the end of its service life and all the astronauts have returned to Earth, only a totally automated space vehicle will be capable of performing the deorbit.

International Space StationISS