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Astronauts say bye, bye ISS
15/07/2006 12:42 - (SA)
Cape Canaveral, Florida - Pilot Mark Kelly fired up steering jets and slowly backed Discovery away from the international space station on Saturday to begin the space shuttle crew's return trip to Earth.
Two hours earlier, Discovery's six astronauts snapped last-minute photos and bid farewell to the space station's crew before closing a hatch for departure.
They left behind former crew mate Thomas Reiter of the European Space Agency, who came up in Discovery for a six-month stay at the station with Russian commander Pavel Vinogradov and US flight engineer Jeff Williams.
"Have a safe journey back, a soft landing and we'll see you on the ground in a few months," said Williams.
Once undocked and about 72 kilometres away from the space station, Discovery's astronauts planned to conduct one final inspection.
The shuttle will stay close enough to the space station to dock again if necessary until it's cleared to return to Earth by mission managers reviewing downlinked inspection images.
The mission, scheduled to end with a landing on Monday at the Kennedy Space Centre, has been viewed as a genuine success by Nasa managers.
One concern
The shuttle launched without any apparent damage to Discovery's thermal protection system.
The transfer of supplies and cargo between the shuttle and station was done much faster than expected. Spacewalking astronauts repaired a crucial rail car on the space station and were able to show that a 15-metre boom attached to a 15-metre robotic arm could be used as a platform to make repairs to the shuttle.
Discovery's crew members set an unofficial record for use of robotics in space, and they delivered Reiter to the space station, raising the number of crew members to three for the first time since the Columbia disaster.
There remained only one concern that could affect the astronauts' planned landing at the Kennedy Space Centre - a slow leak in one of the shuttle's three units that power hydraulic systems used for steering and braking.
It could be leaking harmless nitrogen or flammable hydrazine fuel, but there is no way of knowing that, so Nasa is treating the problem as if the leak were fuel.
To be on the safe side, Nasa will turn on the power unit with the leak early on Sunday as part of its normal testing and then see if the leak rate changes.
If it does, Nasa may burn off the hydrazine and shut down the power unit before the shuttle returns to Earth to eliminate any fire hazard, said John Shannon, the shuttle programme's deputy manager.
If that happens, the shuttle would land with just its two other power units for the first time in the spacecraft's history. The shuttle needs only one power unit to land.
On the net:
spaceflight.nasa.gov
- AP
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