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View Full Version : Next TEGA "Bake" Could Be Last for Phoenix



Fraser
2008-Jul-03, 03:50 AM
The "vibrating" done to get the first Mars arctic soil sample into Phoenix's TEGA (Thermal and Evolved Gas Analyzer) oven may have caused a short circuit that could happen again the next time the oven is used, perhaps with fatal results. A team of engineers and scientists assembled to assess TEGA after a short circuit [...]

More... (http://www.universetoday.com/2008/07/02/next-tega-bake-could-be-last-for-phoenix/)

spacestart.eu
2008-Jul-03, 07:45 AM
That would be a disaster. Let's hope nothing happens with Phoenix!

LotusExcelle
2008-Jul-03, 11:31 AM
Isn't there a Maytag repair man in the area that could help?

t@nn
2008-Jul-04, 01:00 PM
I hope all goes well. If something does happen how much will Phoenix's ability to do research be curtailed? What other options will it have?

01101001
2008-Jul-05, 06:35 PM
I hope all goes well. If something does happen how much will Phoenix's ability to do research be curtailed? What other options will it have?

If TEGA fails next, permanently, that's 7 uses of the ovens they won't get. They will only have the first to go on.

There'll be no TEGA confirmation of soil water ice content. If they detected organics in the first oven, there'll be no dismissing the possibility of earthly contamination -- via testing the OFB, organic-free blank (Lunar and Planetary Institute PDF document (http://www.lpi.usra.edu/meetings/lpsc2008/pdf/1067.pdf)) -- and no chance to follow up with a confirmatory sample.

According to a document -- NASA Mission Design Overview for the Phoenix Mars Scout Mission (http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/40351/1/07-0267.pdf) (PDF) -- minimal mission success depends on testing 2 samples in either the MECA Wet or TEGA, so they would be OK there.

Full mission success requires 3 soil samples through TEGA, so that would be a failure.

I don't know if the feared TEGA failure mode would also eliminate planned sniffing of the atmosphere that I think has yet to happen.

TEGA is a major instrument, but one of a handful on Phoenix (instrument list (http://phoenix.lpl.arizona.edu/science05.php)). And they got at least one sample processed with it. If no more, some science would be lost. Full success would be lost.

dgavin
2008-Jul-05, 06:40 PM
I hope all goes well. If something does happen how much will Phoenix's ability to do research be curtailed? What other options will it have?

Well I hate to be the gainsayer here, but It -has- accomplished two of it's primary goals already, and those are finding water on the soil surface as was theorized, and to find chemicals in the soil that can support certain forms of bacterial life.

There are Eight ovens so if one is lost, we will lose the ability to sample what that oven/gas chromatograph was designed for. I'm not sure what Oven 4 relates too, I'll see if I can find out.

dgavin
2008-Jul-05, 07:13 PM
Ok basically what I found about the design is the Tega is a single unit with 8 Ovens, as seen below during construction.

http://phoenix.lpl.arizona.edu/images/gallery/lg_99.jpg

Each oven receives a certain amount of material for a given sample run. So if one one oven goes down, the following could be the scenarios of some outcomes.

1. Oven 4 Permanently Shorts out, which causes a power drain from the other ovens that prevents the TEGA from being used. If it was turned on it would drain the power of the entire probe in short order.

2. Oven 4 goes offline after a temporary short, the Tega is still usable, but it might not be able to reach the 1000c temperature it needs. There would be a loss of detections for higher melting point elements.

3. Occasionally shorts out, but still functions. The Short seems to happen during the vibration phase of sampling, it may not degrade any further and just be a intermittent -glitch-

Tuckerfan
2008-Jul-05, 07:28 PM
Isn't there a Maytag repair man in the area that could help?

He's working on it. (http://www.angelfire.com/pa/lkmarvin/Pictures/MarsLanding_.jpg)