Spacecraft Health, A cause for concern? |
Spacecraft Health, A cause for concern? |
Jul 1 2008, 12:53 PM
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Member Group: Members Posts: 655 Joined: 22-January 06 Member No.: 655 |
I generally read most of the significant events (S.E) reports that are posted on the Cassini-Huygens website, and the spacecraft is always described as being in excellent health and operating normally.
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 |
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Jul 1 2008, 01:21 PM
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Merciless Robot Group: Admin Posts: 8783 Joined: 8-December 05 From: Los Angeles Member No.: 602 |
Don't think it's too scary yet. If they lose another RWA, I presume that would mean that they'd have to augment maneuvers with the thrusters, but only along one plane; not nearly as bad in terms of propellant consumption as having to use the RCS for all attitude positioning.
I was sort of amazed to learn from that update that the main engine cover has completed 40 cycles since launch. That is really impressive for a moving part that's been directly exposed to space for twelve years! -------------------- A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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Jul 1 2008, 05:04 PM
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Member Group: Members Posts: 213 Joined: 21-January 07 From: Wigan, England Member No.: 1638 |
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 That sounds like a great option, regardless of the outcome! -------------------- "I got a call from NASA Headquarters wanting a color picture of Venus. I said, “What color would you like it?” - Laurance R. Doyle, former JPL image processing guy
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Mar 20 2012, 10:31 PM
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Member Group: Members Posts: 808 Joined: 10-October 06 From: Maynard Mass USA Member No.: 1241 |
Cassini plasma spectrometer is working again after nine months off line.
details... http://news.yahoo.com/instrument-cassini-c...-204927160.html -------------------- CLA CLL
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