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Unmanned Spaceflight.com > Mars & Missions > Orbiters > Mars Express & Beagle 2
SigurRosFan
http://www.nature.com/news/2005/050905/full/050905-10.html

"One of the best chances for solving Mars's methane mystery may have been lost. The Planetary Fourier Spectrometer (PFS) on board the Mars Express orbiter seems to be broken, perhaps for good."

"In 2004, the PFS found that methane averaged about 10 parts per billion in Mars's atmosphere, suggesting that more than 100 tonnes of the gas is released from the surface each year. That same year, Mike Mumma of NASA's Goddard Space Flight Centre in Maryland spotted levels of 250 parts per billion using a telescope in Hawaii. This week he told an American Astronomical Society meeting in Cambridge that he had spotted levels of 44-63 parts per billion from a different part of the planet."
djellison
Well - we're two months from the end of the MEX primary mission - so things breaking is to be expected to some extent, but it's always a dissapointment, especially with something as astonishing as that one.

On the upside, more bandwidth for everyone else.

Doug
BruceMoomaw
I've sent an enquiry to the PFS group asking them to provide more deails on what actually has happened -- and also on what the implications are for the similar PFS on Venus Express. of course, given my past experiences with ESA, I don't guarantee a reply.

One thing that became clear when I read yesterday about the design of this instrument was how astonishingly vulnerable it always has been to vibrations -- it requires positioning of its interferometric mirrors precise to within less than a micron.
BruceMoomaw
By the way, one apparent flaw in that "Nature" article: it says that the next opportunity to measure Martian CH4 won't come until MSL -- but that measurement has now been officially added to Phoenix (although, unlike MSL, it can't do isotopic analyses of atmospheric CH4. MSL can, because its instrument's projected sensitivity is only 20 parts per trillion.)
centsworth_II
What about the Mars flyby of Rossetta? They claim to be able to detect methane and study local variations in its concentration.
http://www.cosis.net/abstracts/EGU05/04196/EGU05-J-04196.pdf
SigurRosFan
New ESA article: Mars Express instrument under investigation

http://www.esa.int/esaCP/SEMSEK7X9DE_Life_0.html

--- ESA has started a technical investigation into the Planetary Fourier Spectrometer (PFS) on board Mars Express, after a problem developed in the instrument a few months ago.

Vibration effects (induced by spacecraft activities) have been suggested as a cause for the observed behaviour. However no source has yet been identified and other causes internal to the instrument cannot be fully ruled out. ---
SigurRosFan
QUOTE (djellison @ Sep 7 2005, 10:36 PM)
... we're two months from the end of the MEX primary mission ...
*
September 16: MEx is extended to end of 2007!
djellison
QUOTE (SigurRosFan @ Sep 21 2005, 02:34 PM)
September 16: MEx is extended to end of 2007!
*


Yup - but the design spec for instrumentation would have been the primary mission - and the PFS just about managed it smile.gif

Doug
paulanderson
Back in business! The PFS has been fixed! biggrin.gif

http://www.esa.int/SPECIALS/Mars_Express/SEM6N9638FE_0.html

See also the new article re methane-producing microbes discovered in arid desert soils that I just posted in the 'Methane Detection' topic (hadn't been updated for a long time but seemed like the best place to post that one):

http://www.unmannedspaceflight.com/index.php?showtopic=143
mike
"back-up motor, more powerful than the first one"? Why have a 'backup' motor that is not exactly the same as the motor it is designed to replace? Were they worried that the first motor might not have enough power, so they built two into it, and they couldn't 'really' test them out until they were in space? Or was this 'back-up motor' actually intended to do something else - maybe it's less accurate and used for getting general readings and then the dead motor would more finely adjust and they found that this 'back-up motor' could actually be just as accurate, or am I missing something...

That just stuck out at me as odd, what can I say..
tedstryk
QUOTE (mike @ Nov 2 2005, 06:07 PM)
"back-up motor, more powerful than the first one"?  Why have a 'backup' motor that is not exactly the same as the motor it is designed to replace?  Were they worried that the first motor might not have enough power, so they built two into it, and they couldn't 'really' test them out until they were in space?  Or was this 'back-up motor' actually intended to do something else - maybe it's less accurate and used for getting general readings and then the dead motor would more finely adjust and they found that this 'back-up motor' could actually be just as accurate, or am I missing something...

That just stuck out at me as odd, what can I say..
*


Depends what they mean by "more powerful." Perhaps during calibration tests it proved to be the more accurate of the two. Of course, that begs the question of why in the hell they made it the backup, but that is the most logical interpretation I make...unless, perhaps, when they turned it on, they realized it simply works better than the previous motor when it was on the brink of death. In that case, it is taking the relatively obvious and making it sound extraordinary...not that ESA would ever do that....
mike
Hmm, yeah, what you say about the backup motor now being the more powerful of the two simply because the other one is basically dead makes sense, and with the fact that most of Europe doesn't speak English, so maybe they slightly mistranslated..

I'm glad they built in a backup motor. I was under the impression that most probes simply don't have entirely redundant backups, since they take up extra weight and space.. Maybe the ESA can find out what the composition of the latest dust storm is. The whole 'tendrils' thing strikes me as odd - why would convection make tendrils like those?
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