Gennady Padalka works on the exterior of the ISS on Tuesday

The ISS lost its orientation for 20 minutes during the extra-vehicular activity (EVA) on Tuesday.

Russian Gennady Padalka and American Michael Fincke were installing navigation and communication aids to ease arrival of a cargo craft.

The new equipment will let the European cargo craft dock automatically.

The astronauts lost contact with ground controllers for around 20 minutes when the ISS shifted after the equipment controlling its position became overloaded.

The movement severed communications, but engineers on the ground swiftly re-aligned the station's position by switching on an engine to one of its modules.

Vladimir Solovyev, head of mission control in Moscow, Russia, even suggested that the astronauts may have "rocked" the station because they were working too hard - leading to the temporary loss of orientation.

"The crew in fact rocked the station, causing three US gyros to stop and the International Space Station to lose its orientation for twenty minutes," he told the Russian news agency Tass.

The "Jules Verne" Automatic Transfer Vehicle (ATV) - Europe's first cargo craft to the ISS - is due to launch next year and will provide a welcome helping hand, as Russia struggles with the burden of being the sole lifeline to the station while Nasa's space shuttles remain grounded.

Helping hand

Russia has launched all manned and cargo ships to the orbital platform since February 2003, when space shuttle Columbia exploded on re-entry, killing the seven crew aboard. Since then, Nasa's remaining shuttle fleet has been grounded.

The 20-tonne ATVs are capable of carrying a much bigger load of food, equipment and fuel than Russia's Progress cargo craft.

Russian craft are currently the only ones travelling to and from the ISS

The European vehicles are also big enough for astronauts based on the space station to work inside them once they dock.

This is Padalka and Fincke's third spacewalk since arriving at the station. The first lasted just minutes before the men were ordered back into their airlock due to an apparent pressure drop in Fincke's oxygen tank.

The ATV will be launched into orbit from an Ariane 5 rocket due to blast off from Kourou, French Guiana in October 2005.