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Save the 2009 Mars rover. . .



 
 
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  #1  
Old February 18th 04, 01:40 PM
Tom Merkle
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Default Save the 2009 Mars rover. . .

No, not from the budget axe or the usual suspects, but from a far more
pernicious foe: the TooMuchNewStuffAtOnceists. I sent the president's
space commission an email suggesting they ensure a 'moon first, then
Mars' testing regimen for the entire initiative, not just human
missions, because of the momentum stalling nature of a billion dollar
failure.

The mission that worries me most in this regard is the 2009 Mars
Laboratory Rover. The current NASA thinking on this rover has it
costing over a billion as a single rover, testing a brand new landing
method (somewhat like an Acme Rocket Flying Trapeze with a landing
radar) and on a larger scale than any other rover past. This leaves
the potential for a '92 Mars Observer sized embarrassment.

While I applaud the increasing size & power systems for the 2009
rover, the dual success of the current rovers can be easily contrasted
against both the '92 Mars Observer and the 2001 Mars failures. We
should consider testing the trickier parts of the 2009 mission on an
earlier (2007 or early 2008) lunar rover that would try out the Flying
Trapeze landing method before we end up smashing a billion dollars of
RTG warmed earth microbes into the Martian subsurface.

Obviously for monetary and political reasons it does not make sense to
rush to send an RTG powered heavy rover to the moon. But a smaller,
solar powered rover with the capability of sleeping through a lunar
night would be a long term, continuing asset for NASA. In addition,
the landing method for the 2009 Mars rover could be tested on this
moon rover with less risk due to a shorter dormant cruise time and
constant monitoring of the process from earth. Lighter gravity of the
moon, along with the smaller weight of a solar rover, should
adequately compensate for the lack of atmospheric slowing that a lunar
lander gets. Most importantly, any problems or pitfalls with the new
landing process could be discovered with plenty of time to correct the
problems before the 2009 Mars Rover(s) ever leaves earth.

That's a way to smartly leverage goals AND new technologies.
comments?

Tom Merkle

Tom Merkle
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  #2  
Old February 18th 04, 03:31 PM
Henry Spencer
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Default Save the 2009 Mars rover. . .

In article ,
Tom Merkle wrote:
Obviously for monetary and political reasons it does not make sense to
rush to send an RTG powered heavy rover to the moon. But a smaller,
solar powered rover with the capability of sleeping through a lunar
night would be a long term, continuing asset for NASA...


Unfortunately, a solar-powered rover capable of surviving the lunar night
is a whole lot easier said than done. RTGs are needed just as badly there.

Lighter gravity of the
moon, along with the smaller weight of a solar rover, should
adequately compensate for the lack of atmospheric slowing...


A solar-powered rover isn't necessarily lighter than an RTG-powered one.
It could easily end up heavier.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |
  #4  
Old February 19th 04, 12:19 AM
McLean1382
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Default Save the 2009 Mars rover. . .

As I understand
it, they intend to demonstrate the trapeze method on Earth, which is
much closer to Martian conditions than is the moon.

Brian


trapeze?

Will McLean
  #5  
Old February 19th 04, 01:13 AM
Ian Stirling
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Default Save the 2009 Mars rover. . .

Henry Spencer wrote:
In article ,
Tom Merkle wrote:
Obviously for monetary and political reasons it does not make sense to
rush to send an RTG powered heavy rover to the moon. But a smaller,
solar powered rover with the capability of sleeping through a lunar
night would be a long term, continuing asset for NASA...


Unfortunately, a solar-powered rover capable of surviving the lunar night
is a whole lot easier said than done. RTGs are needed just as badly there.


Even RHUs would help a lot.
Insulating and trying to add thermal capacity get very hard when you'r
talking about something relatively small that has to stay warm for
over a million seconds.
A few dozen watts of heat in the right place might make all the
difference.
Mars is comparatively benign thermally, compared to the moon.
About all the moon has going for it is that it's a true vacuum, so
MLI works there.

Random thought.

If a little garage, with insulation and a little bit of RHU were put on
the moon, how much work would be needed to be done on Spirit/Opportunity
type rovers to make them work?

Is thermal control it?
  #6  
Old February 19th 04, 01:37 AM
Paul F. Dietz
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Default Save the 2009 Mars rover. . .

Henry Spencer wrote:

Unfortunately, a solar-powered rover capable of surviving the lunar night
is a whole lot easier said than done. RTGs are needed just as badly there.


Laser power beaming?

Paul
  #8  
Old February 19th 04, 02:39 AM
Tom Merkle
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Default Save the 2009 Mars rover. . .

(Henry Spencer) wrote in message ...
In article ,
Tom Merkle wrote:
Obviously for monetary and political reasons it does not make sense to
rush to send an RTG powered heavy rover to the moon. But a smaller,
solar powered rover with the capability of sleeping through a lunar
night would be a long term, continuing asset for NASA...


Unfortunately, a solar-powered rover capable of surviving the lunar night
is a whole lot easier said than done. RTGs are needed just as badly there.


True, but the weight req'd for sufficient heat-producing RTGs is a lot
lower than that for an RTG electrical generator. All you need is a
plutonium lump with a protective sheath. With that it's possible to
nearly eliminate heaters.

Lighter gravity of the
moon, along with the smaller weight of a solar rover, should
adequately compensate for the lack of atmospheric slowing...


A solar-powered rover isn't necessarily lighter than an RTG-powered one.
It could easily end up heavier.


Hmm. That is a problem. An additional problem, after I sketched out
detailed landing profiles for both a lunar and mars rover, showed me
the actual difference between a MER-weight lunar rover with
'outriggers' and the 2009 Mars rover with 'outriggers' is much greater
than the difference between the 2004 MER landing profile and the
purported 2009 landing profile. That aeroshell/parachute makes a big
difference. Doing a lunar rover to 'test the landing profile' for a
2009 rover therefore makes little sense. We'd actually get closer to
testing the real landing profile in an earth-bound suborbital test.

So the conclusion I come to is...it's good idea from the lunar
exploration side of the coin, but not in an incremental test scenario.
Here's how I break it down:
(+) commonality of parts and systems with a 2009 Mars rover would make
the price of achieving both capabilities cheaper than if they were
funded and built separately.
(-) commonality of parts implies same power generation method. The RTG
is what makes the 2009 rover a 2009 instead of 2007 rover, so trying
to accomplish this by late 2007 for a lunar rover might be
problematic.
(-)commonality of parts also implies similar development paths, which
means it could be tough to get the lunar rover done far enough ahead
of time.
(+) testing an autonomous driving feature remotely with earth a half
second away and in constant communication, before trying it out on Big
Red, is a huge plus. Software problems would be easy to identify and
correct well before the 2009 rover reaches Mars.
(+)the moon is a great place to test the hazard avoidance/precise
landing targeting methods, for the same reasons testing the driving
software on the moon makes sense.
(-) a 2007 lunar rover is only 3.5 years away, and it would be tough
to bust it out on such a tight schedule when there's currently no
funding for one. In addition, slippage in launch time could cause
insufficient time to correct any real problems found prior to having
to launch the 2009 mars rover.
(+) the communication bandwidth available to a lunar rover is huge.
That would enable rover enhancement with features (like continuous
video) that make up for the less interesting subject matter.
Profit-making payload could even be funded with companies like
TransOrbital or SpaceDev to allow some of the funding for the project
to be commercial.

My new conclusion: the lunar rover is a great idea in its own right,
but schedule limitations, funding, and moon/mars physical differences
(both atmosphere and day/night length) makes it unlikely as a Mars
testbed.

Tom Merkle
  #9  
Old February 19th 04, 03:19 AM
McLean1382
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Default Save the 2009 Mars rover. . .

Brian Thorn writes:

I've forgotten the name for the concept, but the MSL will come down on
a parachute. A few hundred feet up, the backshell will release the
chute and fire up descent engines. Closer to the ground, the backshell
will winch out the lander on a cable until the MSL touches down. The
backshell will steer a safe distance away and crash.

Theoretically, this gives the lander the ability to pick and choose
its landing site, avoiding big boulders, etc.


What is the advantage of this compared to a Viking style lander?

Will McLean
  #10  
Old February 19th 04, 06:20 PM
Andrew Gray
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Default Save the 2009 Mars rover. . .

In article , McLean1382 wrote:
Brian Thorn writes:

I've forgotten the name for the concept, but the MSL will come down on
a parachute. A few hundred feet up, the backshell will release the
chute and fire up descent engines. Closer to the ground, the backshell
will winch out the lander on a cable until the MSL touches down. The
backshell will steer a safe distance away and crash.

Theoretically, this gives the lander the ability to pick and choose
its landing site, avoiding big boulders, etc.


What is the advantage of this compared to a Viking style lander?


You get to pick and choose the landing site, avoiding big boulders,
etc... ;-)

As a quick thought experiment, visualise the way a Viking-style lander
comes down... engine firing, legs touch, kill engine. Sits there on the
sand with a foot of clearance.

Now visualise a nice, solid, reasonably unsmooth 18" rock underneath
it... as if it were coming down on top of one of the boulders you see in
the Pathfinder pictures. Much wailing and gnashing of teeth, tearing of
hair, tearing of descent engine, that sort of thing...

It lets you avoid that; it's pure luck we haven't hit any (probably; we
can't be too sure about some of the failure modes for the failed
ones...)

--
-Andrew Gray

 




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