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Greg D. Moore (Strider) wrote:

Stupid question, but what exactly in the electronics dies from being cold?

Materials that are bonded to each other but which have dissimilar thermal
expansion coefficients will eventually develop small cracks and lose circuit
integrity if repeatedly temperature cycled over an extreme range. Batteries,
printed circuit boards, and devices are all potentially at risk.

--
Dave Michelson

"Henry Spencer" wrote in message
...
In article ,
Greg D. Moore \(Strider\) wrote:
The night-time cold is likely to kill the electronics before power
shortages become acute, though.

Stupid question, but what exactly in the electronics dies from being
cold?

The problem is not so much being cold, as going from a little bit cold to
a lot cold, and back again, over and over. Because different materials in
the electronics -- e.g., the circuit-board material and the copper
"wiring" lines plated onto it -- have different coefficients of thermal
expansion, this drastic thermal cycling stretches and strains them.
Sooner or later some of them start cracking.

Thanks, that's sorta what I was thinking.

Hmm, now we just have to find thermal vents on the surface of Mars. :-)

(And next time just launch a damn RTG. )

On Wed, 07 Jan 2004 13:48:03 GMT, Diane Wilson
wrote:

Then it's pretty poor planning to have only one sun available.
I mean, what if it goes out?

....Pat, Diane thinks she's you, now :-P

OM

--

"No ******* ever won a war by dying for | http://www.io.com/~o_m
his country. He won it by making the other | Sergeant-At-Arms
poor dumb ******* die for his country." | Human O-Ring Society

- General George S. Patton, Jr

On Thu, 8 Jan 2004 01:57:45 GMT, (Henry Spencer)
wrote:

This is almost certainly what killed Mars Pathfinder. It's unlikely to be
an accident that MP died soon after the demise of its battery, and thus of
its ability to heat its innards at night. (MP's specs called for a
relatively short surface life, so its designers chose a lightweight
battery that was good for only a limited number of cycles.)

....Wasn't there a "best guess" estimate on how long Sojourner went
around in circles around Pathfinder before solar cell efficiency
dropped below levels required to power it? I still keep having this
vision in my head of Pathfinder being found in the next hundred years
with a foot-deep trench around it with Sojourner still running at
least when the sun's directly overhead :-)

OM

--

"No ******* ever won a war by dying for | http://www.io.com/~o_m
his country. He won it by making the other | Sergeant-At-Arms
poor dumb ******* die for his country." | Human O-Ring Society

- General George S. Patton, Jr

Henry Spencer wrote:


This is almost certainly what killed Mars Pathfinder. It's unlikely to be
an accident that MP died soon after the demise of its battery, and thus of
its ability to heat its innards at night. (MP's specs called for a
relatively short surface life, so its designers chose a lightweight
battery that was good for only a limited number of cycles.)


Was it the RTGs on the Vikings that gave them such a long life- by
keeping the innards warm?

Pat

OM wrote:



Then it's pretty poor planning to have only one sun available.
I mean, what if it goes out?



...Pat, Diane thinks she's you, now :-P




Hey Boss, da sun- he to young to be going out.
Dat what a scientist tell me.
But Saturn, she already engaged- he say she has a ring.
We ain't even a-going to talk about Uranus.... :-P

Chicolini

Am 7 Jan 2004 23:49:51 GMT schrieb "Andrew Gray":

kill them due to lack of power. (Some observations can take as much
as 12-24 hours, with a predicted life of 90 days that means they need
to get moving as soon as reasonably possible.)

Is that 90 days or 90 sols, BTW?

The uncertainity about real life time is bigger than the difference
between a Martian and a Terrestrial day. The MERs are not located on
the moon, where the difference would be significant...

cu ZiLi aka HKZL (Heinrich Zinndorf-Linker)
--
## In TN it is estimated that there are 17 guns per household.
# Whoo, hoo, hoo, I am going to move to Tennessee then.
I've been trying to persuade my friends to conform to the 17 gun
rule, but they don't seem willing to sell down to that average.
(Nick Hull in rec.guns)

In article ,
Pat Flannery wrote:
This is almost certainly what killed Mars Pathfinder. It's unlikely to be
an accident that MP died soon after the demise of its battery, and thus of
its ability to heat its innards at night. (MP's specs called for a
relatively short surface life, so its designers chose a lightweight
battery that was good for only a limited number of cycles.)

Was it the RTGs on the Vikings that gave them such a long life- by
keeping the innards warm?

Right. Having plenty of power available during the night makes a huge
difference. (For bonus points, work out a way to use the waste heat of
the RTG to help... That hasn't been done, except in that Cassini's RTGs
help keep its propulsion system warm, but it has been proposed.)
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |

In article ,
om@our_blessed_lady_mary_of_the_holy... _facility.org says...
On Wed, 07 Jan 2004 13:48:03 GMT, Diane Wilson
wrote:

Then it's pretty poor planning to have only one sun available.
I mean, what if it goes out?

...Pat, Diane thinks she's you, now :-P

Nonsense. I'm Jim Oberg, just like everyone else.

Diane

"Diane Wilson" wrote in message
k.net...
In article ,
om@our_blessed_lady_mary_of_the_holy... _facility.org says...
On Wed, 07 Jan 2004 13:48:03 GMT, Diane Wilson
wrote:

Then it's pretty poor planning to have only one sun available.
I mean, what if it goes out?

...Pat, Diane thinks she's you, now :-P

Nonsense. I'm Jim Oberg, just like everyone else.

Diane

That's good. Very good.