The space shuttle Discovery is about to get its first in-flight examination for hits from micrometeoroids and space junk.
On Friday, Discovery鈥檚 astronauts will use a 15-metre boom extension to the orbiter鈥檚 robotic arm to look for damage to its left wing. They will compare the images gathered with those taken earlier in the flight 鈥� any new dings could be the work of space junk or micrometeoroids (see Space debris impacts on shuttle mission).
The astronauts will repeat the process for the right wing and the orbiter鈥檚 nosecap after undocking with the International Space Station (ISS) on Saturday. Performing the inspection on those areas is difficult when the shuttle is docked.
Advertisement
The examination is the result of a recommendation by the Columbia Accident Investigation Board (CAIB).
The shuttle Columbia was ultimately destroyed in 2003 by a piece of foam insulation that broke from the external tank and put a hole in the orbiter鈥檚 wing, allowing hot plasma to enter the breach during atmospheric re-entry.
But the CAIB said that NASA needed to do more to protect against space junk and micrometeoroids that could also create holes in the orbiter. This mission marks the first such inspection.
Pressure drop
On Thursday, the shuttle crew took their first day off since flying into space on 4 July. But the team at mission control was busy looking into some small problems with the shuttle.
They had identified glitches with two of the orbiter鈥檚 three Auxiliary Power Units. The APUs power different hydraulic elements necessary for landing. These include the landing gear brakes, the rudder/speed brake and steering for the nosewheel.
The shuttle needs only one APU to land, and all three power units are still working. 鈥淲e fully expect them to be fine and operational for the landing,鈥� says Johnson Space Center spokesman James Hartsfield.
But there may be a small leak on APU 1. Flight controllers have noticed a small, gradual drop in pressure 鈥� amounting to 151,700 pascals (22 pounds per square inch) over eight days 鈥� which may indicate a leak, flight controllers said.
The leak appears to be in a fuel tank, but it is not clear what is leaking. It could be nitrogen 鈥� which is used to pressurise the tank 鈥� or hydrazine, the fuel. As Discovery was being prepared for launch, technicians fixed a nitrogen leak in this tank, leading some to believe that the current problem may also be a nitrogen leak.
In addition, the thermostat for APU 3鈥檚 heaters may not be working properly. 鈥淎PU 3 is not considered failed for entry at this time and there are no significant impacts to entry operations,鈥� flight controllers wrote to the crew on Thursday.
Keep up-to-date on the mission by visiting our .
