A pump on the system failed at the weekend due to a power surge which tripped the circuit breaker, requiring the loop which pushes liquid ammonia through the plumbing lines to be shut down. Lucky for them, there are 4 spare pumps kept on the ISS but unfortunately it will require astronauts to go outside the space station in order to replace the faulty part.
The complicated spacewalks are now scheduled for Friday and Monday, allowing a little more time for astronauts on Earth to conduct more underwater practice sessions at NASA’s huge spacewalk rehearsal pool in Houston, Texas, USA.
In an ideal world NASA engineers would like the faulty pump returned to Earth to determine why it failed but for now, regrettably, there is no room remaining to bring it back on the last scheduled shuttle missions. Let’s hope they have plenty more spare parts available in the ISS store cupboards for future mishaps, as transport capacity will be reduced if plans to cease shuttle flights go ahead.
Note added 06/08/10
Spacewalk dates put back again - first to take place on Saturday 07/08/10 and second on Wednesday 11/08/10.
Hmmmmm . . . . . . . we shall see but hoping it all goes well.