Mars Rover longevity again limited by dust build-up

"Manfred Bartz" schrieb im Newsbeitrag ...
"Ool" writes:

Yeah! All these "Close Encounters" type missions, and in all
this time, when was the last time we had a rover roam the Moon?
That's a place whose resources could actually help us on Earth--
solve our energy problems and all that.

Nonsense.

Now, now! There is no reason to get emotional and all negative in
your reply after the objective and dispassionate way in which I've
made my point!


If you are after resources you don't go down another gravity well.
You'd be much better off exploiting NEOs, especially the Ni-Fe ones.

Granted, that's an alternative. But I don't see us doing that, ei-
ther.

(Even if a Moon base were the priority, hauling in volatiles from
NEOs for life support would probably be cheaper than getting them
from Earth. So that could be the next target anyway...)


And it would be the ideal jumping board to the rest of the Solar
System, if we were able to build and launch rockets from up there.

Nonsense again.

Assembling inter-planetary ships in free-fall makes a lot more sense
than at the bottom of a gravity well.

It's a shallow well. Look at the spindly LEM! And if you got mass
accelerators working you wouldn't even need any fuel to shoot stuff
into orbit. Once the raw material were there you could assemble it
in free fall, if that is really easier. (Maybe it is, maybe not. I
really couldn't say.)

The problem with deep space is just that there's nothing to assemble
anything from. (But we were talking NEOs, so maybe there is.)

The other problem I see is radiation. On the Moon you can dig your-
self in and work in polar craters providing natural shielding that
you don't have to bring with you from Earth. Would NEOs provide
shielding? They probably have quite a spin, most of them, with no
places where the Sun don't shine...


("Aluminum, silicon, oxygen, low gravity and lots of solar ener-
gy to be had..." *That's* music to my ears!

Lets talk about exploiting NEOs then. I am all for it.
Same with solar power satellites.

For which you need material.

And space based, solar powered antimatter factories.

That's a little too deep into science fiction for me. Meaning I
haven't heard that we can do that, so I'm assuming we can't. Same
with space elevators. Maybe as soon as ten years from now the ma-
terials can be made at the required length, but as of now they can-
not.

Technology and know-how for mining the Moon (or NEOs for that mat-
ter) exists today, though. And for building SPSs.

What's the deal with Mars if we haven't even built a base on the
Moon yet?

What would a base on the Moon achieve?

If it were just another ISS, only more expensive, not much. But if
the goal of mining the place were achieved, for rocket fuel and so-
lar panels--whether you leave them on the lunar surface or launch
them into GEO--it could really get us somewhere.

About the only thing I can
think of is to learn how to build a base on Mars.

Not just Mars. Anywhere. Mars is a much more useless place in my
opinion, though, even if it were closer. It has an atmosphere, so
you couldn't launch anything into space with mass accelerators.

And as you rightly
ask "what's the deal?" The answer might be "tourism", but probably not
much else.

Tourists would grow tired of the monotony of the Moon soon. It
would be just a fad. After the novelty is gone no one would shell
out the millions any more to go there. (I think. My understand-
ing of human nature is poor, though.)

Why do I get the feeling space exploration is funded by people who
get their idea of what's important from the head- lines of the
National Enquirer?

Hmm, maybe space exploration *is* funded by people who get their idea
of what's important from the headlines of the National Enquirer?

It's all a conspiracy by the Men in Black, I tell you!

What's the deal with trying to find life out there?

Big deal or not, I am not *that* much focused on life on Mars. My
comment reflects more of a resentment that the science package on the
current rovers will not produce science commensurate with the expense.
All we'll get in the end is another IMAX movie and some more evidence
(probably still inconclusive) of past water. IMHO, that isn't
ambitious enough for 800M$.

Well, that was my point, too--that people have no sense of priori-
ties.

Water on the Moon interests me more. But I don't count on it. The
point is, if an industry on the Moon could be sustained, (which is a
big "if," granted) it could send probes to Mars every week. With
tiny rockets, compared to what you have to launch from Earth.

Of course no industry can work these days without human beings, and
keeping them alive and working is the expensive part. The one argu-
ment I can think of against Lunar mining today is, why do it now
when it's hard if in a few decades it will be easy, through the mir-
acles of robotics and cybernetics.

But then, if everyone thought like that we'd never even *get* to the
stage of versatile robots. Think of the Mars rovers not so much as
a science mission but a technological challenge mastered.

And *now* let's build rovers that can withstand lunar temperature
extremes and survive the night there!


I mean, it still doesn't mean that *we* could live there, and that's
all that counts!

Humans now have the ability to live nearly anywhere thanks to our
technology. The only thing missing at this stage is the will to do
this on a large scale.

AFAICS, about the only good reason to build bases on the Moon and on
Mars would be if it is done with the long term intention of creating
self-sufficient human colonies. And why would we want to do that?
-- As a contingency against a doomsday event I suggest.

Solar power stations would be an elegant solution to energy problems,
and if they're ever to be built, Lunar material would be a cheap sup-
ply. There's probably no rush to insure us against Armageddon, and
maybe it'll happen all by itself in a few years anyway... (Like fly-
ing.)

Still, I wish people had a better idea of what space could offer us.


I wrote my previous post before I've heard that the Prez may announce
plans for a Lunar base or, at the very least, more Lunar exploration.
'Bout time, if you ask me! I could forgive him a lot if that actual-
ly happened... (Another big "if!")

"Ken Taylor" schrieb im Newsbeitrag ...
"Ool" wrote in message
...
"Stanislaw Sidor" schrieb im Newsbeitrag
...
Newsuser "Manfred Bartz" wrote ...

Personally I think the Beagle mission had a better and more ambitious
science package. They were going to look for past and present life,
not just at a few rocks in search of past water activity. Oh well,
maybe a few missions down the track we'll get serious.... :/

Do you think, that SETI is a 'good science'?

Yeah! All these "Close Encounters" type missions, and in all
this time, when was the last time we had a rover roam the Moon?
That's a place whose resources could actually help us on Earth--
solve our energy problems and all that. And it would be the
ideal jumping board to the rest of the Solar System, if we were
able to build and launch rockets from up there.

("Aluminum, silicon, oxygen, low gravity and lots of solar ener-
gy to be had..." *That's* music to my ears! As opposed to:
"Ancient fossilized microbes found on meteorite--maybe." So
what, even if they were??)

I'm not aware that we've run low on Al, Si or O2 just yet.

Not for Earth, dude! For space! There isn't that much of it in
the emptiness of space. You either shoot it up there from Earth
or from them Moon. From the Moon is cheaper--theoretically, if
you can build and maintain facilities there. Near Earth orbit
asteroids are another possible supply of all sorts of materials
needed for large orbital power stations.

There's also a
bit of solar energy available in this half of the world. If you really want
to go into space to get it, go to earth orbit, no need to go to the moon
(much longer power cord!).

You go to the Moon for the *materials,* not the location. Much
cheaper to launch-- Wait, I've covered that point.

"Ool" wrote in message ...

("Aluminum, silicon, oxygen, low gravity and lots of solar ener-
gy to be had..." *That's* music to my ears!

The problems of "long distance, hostile environment, high shipping
costs, and high labor costs," are some sour notes that might ruin the
song. They might not, but I bet a solar power plant on Earth would be
more affordable than on the moon - far fewer hurdles to clear.

What's the deal with Mars if we haven't even built a base on the
Moon yet? Why do I get the feeling space exploration is funded
by people who get their idea of what's important from the head-
lines of the National Enquirer?

Trying to replicate what's mostly available now on Earth in the hopes
that the moon's lower gravity will make space travel easier/cheaper is
an expensive gamble. You might win, or you might watch a "$10 billion
project with big ROI" turn into a $100 billion white elephant.

Mike Miller, Materials Engineer

On 4 Jan 2004 18:10:05 -0800, (Christopher M.
Jones) wrote:

They are well aware of the problem. It's a non-problem
problem. The real problem is the cold, that's going to
kill the rover stone dead with absolute certainty in a
few months.

Why will cold kill it? I know excessive heat is bad for electronic
components, but I thought microchips if anything worked better at
lower temperatures?

--
"Sore wa himitsu desu."
To reply by email, remove
the small snack from address.
http://www.esatclear.ie/~rwallace

On Fri, 9 Jan 2004 18:38:47 +0100, "Ool"
wrote:

Yeah! All these "Close Encounters" type missions, and in all
this time, when was the last time we had a rover roam the Moon?
That's a place whose resources could actually help us on Earth--
solve our energy problems and all that.

What energy problems? Earth possesses a vast abundance of energy.

Anyway, the moon is a worthless ball of slag. Not only is Mars much
more interesting scientifically, but it's much better from a material
viewpoint. (Water, nitrogen, mineral resources, gravity that just
might be strong enough to let you live there without destroying your
health.)

And it would be the
ideal jumping board to the rest of the Solar System, if we were
able to build and launch rockets from up there.

Little or nothing to use as rocket fuel, and a lousy place to work.
It'd probably cost several orders of magnitude more to assemble and
launch a Mars mission on the moon compared to on Earth.

("Aluminum, silicon, oxygen, low gravity and lots of solar ener-
gy to be had..."

These things are abundant everywhere in the inner solar system.

What's the deal with Mars if we haven't even built a base on the
Moon yet?

Building a manned base on the moon would cost orders of magnitude than
NASA's entire current budget, and would produce nothing whatsoever of
value in return.

Why do I get the feeling space exploration is funded
by people who get their idea of what's important from the head-
lines of the National Enquirer?

Because it is. They're called "taxpayers".

What's the deal with trying to find life out there? I mean, it
still doesn't mean that *we* could live there, and that's all
that counts!

Well, it's the main thing that counts. But for sustaining human life
outside Earth, the issues aren't in aerospace technology at all - we
already have the means to reach the planets. The issues are in the
basic enabling technologies like robotics and nanotech - so I'd
suggest lobbying for more funding for those areas.

--
"Sore wa himitsu desu."
To reply by email, remove
the small snack from address.
http://www.esatclear.ie/~rwallace

In article ,
Russell Wallace wrote:
...The real problem is the cold, that's going to
kill the rover stone dead with absolute certainty in a few months.

Why will cold kill it? I know excessive heat is bad for electronic
components, but I thought microchips if anything worked better at
lower temperatures?

The problem is not so much cold in itself, but the huge temperature swings
during the day-night cycle. The total swing from daily high to daily low
there is typically 80degC -- like going from a hot day in Mojave to a cold
winter's night in Alberta.

The electronics won't see the full extent of that right away, because they
have electrical heat during the night... but as Mars moves farther from
the Sun, and Sun angles at the landing site deterioriate with seasonal
change, and the rover's battery gradually wears out, less and less energy
will be available at night. And so the electronics will see increasing
temperature swings, and increasing thermal-contraction stresses between
different materials. Fairly soon, things will start to crack.

Mars Pathfinder died shortly after its battery gave out.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |

(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. 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."

Nor is dust accumulation the only "energy crisis" faced by the rover.
Rechargable battery technology still pretty much sucks; even after over
100 years of research, the performance of most rechargable batteries
degrades significantly after only a few hundred or so deep discharge cycles
(which is one of the reasons we _still_ don't have practical electric cars!_).
Even if we _could_ find a way to clean the solar panels effectively,
the rover's rechargable batteries will gradually lose the ability
to store enough of the excess energy produced by the solar panels during
daylight to allow the rover to survive the cold of the martian night...


-- Gordon D. Pusch

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

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?

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. 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."

Nor is dust accumulation the only "energy crisis" faced by the rover.
Rechargable battery technology still pretty much sucks; even after over
100 years of research, the performance of most rechargable batteries
degrades significantly after only a few hundred or so deep discharge cycles
(which is one of the reasons we _still_ don't have practical electric cars!_).
Even if we _could_ find a way to clean the solar panels effectively,
the rover's rechargable batteries will gradually lose the ability
to store enough of the excess energy produced by the solar panels during
daylight to allow the rover to survive the cold of the martian night...


-- Gordon D. Pusch

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

(Henry Spencer) writes:

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

So it's just the _mechanical_ stress that causes all the problems?

--
Markus Redeker Hamburg, Germany

"Archibald" wrote in message
...
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?

Existing RTGs are too big and weigh too much for Spirit and
Opportunity.