The reason for this post is that the latest S.E report see here states:
"AACS is continuing to investigate the significant change in RWA-2 friction test results. This has not affected any overall pointing or other spacecraft performance to date"
As I understand it, there are four RWA (reaction wheel assemblies) which control attitude and pointing when thrusters are not used. Three of the RWA's are used at any one time. RWA-3 was switched to RWA-4 in July 2003 after problems with 'oscillations' leaving three usable RWA's.
If RWA-2 is also experiencing problems, is this a cause for concern re: future spacecraft science, as a failure would result in having to use the reaction control subsystem (i.e thrusters), with subsequent loss of some pointing/stabilisation accuracy, and the much-increased depletion of consumables.
On the first day of the extended mission, should we be:
1) Concerned like hell for some of the XM science
2) A little concerned, consumable use may rule out an XXM in the event of RWA-2 failing, but the XM is safe
3) A little worried, but the problem can be worked around with other in-built subsystem redundancy
3) Not worried at all - Jase should stop being a panic-merchant and lie down in a darkened room with a beer and some soothing music
