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Mars Rover longevity again limited by dust build-up



 
 
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  #41  
Old January 21st 04, 02:26 AM
groutch
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Default Mars Rover longevity again limited by dust build-up

Gordon D. Pusch wrote:
(groutch) writes:

I was wondering why NASA accepts a shortened life for the Mars Rovers
due to "dust build-up on the solar panels".

Is cleaning them beyond their rocket scientists ?


Cleaning hyper-fine dust off of darned near _anything_ is MUCH harder
than you apparently realize.


I ( as far as you know ) realise nothing. I was merely asking a
question about the abilities of NASA.

NASA was unable to find a good way to
clean hyper-fine moondust off the Apollo astronaut's space-suits,
so that dust accumulation was already causing severe problems in the
spacesuit glove/wrist joints after only a few days --- and mars dust
appears to be even "stickier" than moondust, perhaps because there is
just _barely_ enough water in it to make it "muddy."


Apollo was more than 30 years ago - I think it is time NASA invested
more money in fixing this sort of boring (to some) problem than
spending billions on doing whatever Earth observation happens to be
trendy at the moment. One student's paper does not constitute an
attempt at a fix.


Credit where credit is due, though: NASA learnt from previous mistakes
and used technology ( the 256 tones ) to let them know what, if
anything, was going wrong with a probe that might well have failed.
( Don't know how well it worked ? - they seem scared of using big
words on their web site).

Brickbats where brickbats are due: If only ESA had invested in ( a
copy of ) that technology, Beagle might have provided something for
future missions, instead of a big, "we only had 65 million dollars",
Nada. ( No idea about Mars Express's success - the ESA website is
SH... less than up-to-date ).


Groutch.
  #42  
Old January 21st 04, 04:45 AM
Gordon D. Pusch
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Default Mars Rover longevity again limited by dust build-up

Archibald writes:

Hmm...i still don't see what's so wrong with RTG's? They are cheap,
reliable and have high energy density. Is there a ban on using RTG's or
what?


Not yet. But RTGs are considered _VERY_ "politically incorrect" by the Greens,
and every time one is launched, Greenpeace will picket NASA, Mitch Kaku will
appear on Nightline to tsk-tsk NASA for doing something so Environmentally
Threatening, and Jeremy Rifkin will file a strategic nuisance lawsuit, in an
attempt to get a Federal Judge to issue an injunction to Stop The Countdown
Until A Proper Environmental Impact Statement Has Been Filed And Processed
(by which time the launch window would have long since closed, effectively
canceling the launch).

Also, the stack of bureaucratic paperwork required to certify and launch
a vehicle carrying an RTG is exponentially higher, so NASA prefers to
avoid it unless it has Absolutely No Other Possible Alternative.


-- Gordon D. Pusch

perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;'

  #43  
Old January 26th 04, 02:14 PM
Jan C. Vorbrüggen
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Default Mars Rover longevity again limited by dust build-up

Brickbats where brickbats are due: If only ESA had invested in ( a
copy of ) that technology, Beagle might have provided something for
future missions, instead of a big, "we only had 65 million dollars",


I believe Beagle 2's budget was more in the range of 5 million GBP. The
whole thing has a diameter of 60 cm or two feet for you Imperialists -
no place for gadgets.

Nada. ( No idea about Mars Express's success - the ESA website is
SH... less than up-to-date ).


Mars Express is extremely successful - I'm sure ESA's website has things
to say about it, as I've read and seen some of it myself.

Jan
  #45  
Old January 28th 04, 02:30 AM
Henry Spencer
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Default Mars Rover longevity again limited by dust build-up

In article ,
Russell Wallace wrote:
...And so the electronics will see increasing
temperature swings, and increasing thermal-contraction stresses between
different materials. Fairly soon, things will start to crack.


That makes sense, though I'm surprised it isn't possible to find
materials that don't crack when put through heating/cooling cycles. Or
is it the case that it could be done, but would cost more than it'd be
worth?


There is very limited room to maneuver on this, because you need materials
that can do their jobs in other respects. In practice, one tries to avoid
gross mismatches of thermal expansion anyway, because there is some
exposure to heat in soldering etc., but often there is little or no choice.

And yes, economics do enter the picture as well. The MER project couldn't
possibly have afforded to custom-make all its ICs, for example.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |
 




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