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Subject: SPACE Digest V10 #332

SPACE Digest                                     Volume 10 : Issue 332

Today's Topics:
               Re: Mars rovers
              Re: SPACE Digest V10 #317
         Multi-national (MANNED) Mars Mission
        Re: Manned vs Unmanned Mission to Mars
----------------------------------------------------------------------

Date: 10 Dec 89 03:41:46 GMT
From: cs.utexas.edu!jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Mars rovers

In article <[e-mail]> [e-mail] (Jorge Stolfi) writes:
>John Roberts argues that a Mars rover can be safely teleoperated from
>Earth by simply making it move slow enough.  Herman Rubin replies:
>>
>>   Sorry, no go.  Suppose one could scan 1 square mile in a day.
>>   Then the state of Delaware would require years.  At one
>>   mile/day, it would take two years to travel from Chicago to New
>>   York.
>
>Does this sound like nothing to you?

Actually, it sounds far too good to be true.  How do you scan a square
mile in one day with a rover that is only allowed to move about 35 times
in that day?  (I assume daylight-only operation, and a 20-minute round-
trip delay -- it actually varies from 7 to 37.)  In rough -- i.e.,
interesting -- terrain, that strikes me as a *linear* distance of only
a few hundred meters.

>...[manned rovers]  Increased weight and wheel
>propulsion require a more powerful motor and a heftier energy source;
>which means solar cells and RTGs are out...

Actually solar cells are out anyway, because of the dust storms, which
can drop the net sunlight at the surface to near-zero for a month or
more.

>... Finally, a manned rover needs to be
>designed more conservatively than an unmanned rover, which means still
>more dead weight and *lots* more money.

More conservatively than the current unmanned designs?  I doubt that,
actually.  Remember, the unmanned ones are designed around the theory
that this is a once-in-a-lifetime mission which is not allowed to fail,
with no on-board repair capability.

>>   But one mile a day is about 3.7 feet/minute.  When there is a
>>   20-minute delay, this is more than 70 feet.  This is still too
>>   far.
>
>I guess it depends on the terrain.  On a flat plain with a few
>scattered rocks here and there, a camera mounted a couple of meters
>above ground should be able to see quite a long way ahead.

Flat terrain is relatively uncommon on Mars.  Ask people who've really
studied transportation on Mars -- Mars is *rough*, especially in the
interesting regions like the edges of the polar cap.  Designing surface
transport that will work *without* teleoperation delays is a challenge.
(Some of my friends were involved in the Planetary Society's Mars-surface-
transport design competition a couple of years ago.)

>Also, it doesn't seem hard to install some simple sonar sensors and
>whiskers on the vehicle, and program it to stop automatically when it
>senses any unexpected bump or dip on the road ahead...

Remember that the Martian atmosphere is a poor grade of vacuum.  I'd be
doubtful about making a workable sonar system.  A scanning laser range-
finder might do.

>On a more rugged
>terrain the speed may fall down to a few feet per hour, but such a
>terrain would probably be off limits to a manned rover anyway.

Are we trying to establish the capabilities of an unmanned rover with
long teleoperation delays, or compare it to manned rovers?  Please stick
to one or the other.  Terrain that can only be covered at a few meters
per hour will probably be off-limits to long-delay teleoperated rovers
as well, simply because traversing any substantial area of it would
take up too much of the rover's expected lifetime.

>I find it amazing that people can argue so vehemently that teleoperated
>rovers Can't Possibly Work, as if the Russian Lunokhod rover had never
>existed.  Sure, it was only the Moon, not Mars; but are we to conclude
>that 10 years from now the US will not be able to even *try* improving
>on what the Russians did 20 years ago?

The Soviets moved the Lunokhods very slowly, and did have some trouble
with teleoperation delays.  We're talking about a delay two orders of
magnitude longer, minimum.  That is not a frivolous side issue, it is
*the* problem.  The speed of light has not increased noticeably in the
last 20 years.
--
1755 EST, Dec 14, 1972:  human |     Henry Spencer at U of Toronto Zoology
exploration of space terminates| uunet!attcan!utzoo!henry [e-mail]

------------------------------

Date: 9 Dec 89 07:15:14 GMT
From: sun-barr!cs.utexas.edu!jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: SPACE Digest V10 #317

In article <08DEC89.16649801.0013.MUSIC@SDSUMUS> [e-mail] (Andy Edeburn) writes:
>> 1233 EST, Dec 7, 1972:         |     Henry Spencer at U of Toronto Zoology
>
>  I'm sorry Harry, but you're wrong on this time. Apollo 17 was launched
>at 0033 EST. It was the first night and last night launch of a Saturn V.

Hmm, right you are, and I knew that too.  (Stayed up late to watch it.)
Must have flubbed an AM/PM conversion somewhere.
--
1233 EST, Dec 7, 1972:         |     Henry Spencer at U of Toronto Zoology
last ship sails for the Moon.  | uunet!attcan!utzoo!henry [e-mail]

------------------------------

Date: 9 Dec 89 23:35:16 GMT
From: stan!katmandu![e-mail]  (Stephen Matson)
Subject: Multi-national (MANNED) Mars Mission


 I'm surprised that in the discussion over manned vs. unmanned the
 subject of a multi-national mars mission has not come up yet (or
 did I miss it ?).

 A Multi-National Mars mission would serve the goals of ;

  Cost reduction on a per-nation basis. ( tho the U.S. and U.S.S.R. would
  probably flit most of the bill)

  Putting together the best technology know-how of the participating
  nations, The USSR's heavy lift boosters, The USA's computer systems,
  Japans manufacturing skills, ETC....

  The World Space Agency formed to oversee a Mars mission would serve
  as the foundation for a more agressive exploration/colonization
  effort with ( hopefully ) more vision and commitment then any one
  nation could possibly keep up by itself for long.

  And foremost (IMHO) it  would serve to excite  (most)  of the worlds
  people and bring a vision of a United ( Ok, Confederated) World reaching
  out to the planets, then one day the stars, Closer.

 Most people I know think that one day Humans will colonize the planets,
 but not in our lifetime. Why not ? If there was a Multi-national effort
 put forth to explore Mars, it would bring down some of the lingering
 walls of mistrust. And then think what we could do as far as Space
 exploration/research/colonization (not to mention hunger, etc)
 if we did not have to maintain a gigantic military.

 Personally I *like* the idea. I think the formation of a W.S.A. is
 inevitable, its just a matter of when.


 I also think the space station should be more multi-national.


               Any comments ?????

             Steve.
--------
" What we could do with 10% of the worlds military budget....." Me

--
 E-mail == [e-mail]
  "FRODO LIVES"                                "COLORADO!!"
------------------------------------------------------------------------------
             Support the formation of a World Space Agency.

------------------------------

Date: 10 Dec 89 00:24:56 GMT
From: attcan!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Manned vs Unmanned Mission to Mars

In article <[e-mail]> [e-mail] (Jim Bowery) writes:
>The only reason we aren't flying probes the way we were in the 60's
>(fire off a few to different places, find out something, quickly send others
> to answer questions raised by earlier ones) is because NASA assasinated
>our space transportation capabilities with the Shuttle Program.

Oh, nonsense.  Jim, have you ever read, e.g., the reports of the Solar
System Exploration Committee?  The Galileo mission, in particular, has
suffered considerably from the Shuttle's problems, but that's not the
main reason for the decade-long hiatus in major planetary missions.
The real problem is that the planetary-science people got caught in
a vicious circle of bigger and more complicated and less frequent missions.
Galileo, to pick an example, had launch-vehicle problems partly because
it kept getting bigger and fatter.  It also ate up almost all the funding
for such missions for several years, interfering with a lot of smaller
science missions that would have yielded results sooner.

The SSEC's proposed solution -- the Planetary Observer program, with steady
yearly funding to launch a series of relatively small and unambitious
missions to the inner planets -- unfortunately hasn't worked.  It looked
plausible, given that the Explorer series of space-science missions (COBE
being the latest) runs quite well that way.  Unfortunately, Mars Observer
caught a serious case of Galileoitis, with the resulting budget overruns
and schedule slips.  Nearly a decade after the Observer program was
conceived, it still hasn't flown its first mission and doesn't even
have approval for the second.  And the hoped-for steady funding for the
Observer program simply has not appeared.  Using the shuttle as a
launcher did not cause its problems, and abandoning that policy has not
magically cured them.

For all the harm that the Shuttle-only policy did, one must beware of
casting it (and its lingering influence in NASA) as the Great Satan,
to blame for all the space program's woes.  The real problem here is
not the choice of launcher, but hardening of the arteries in NASA and
Congressional micromanagement.  Between its own bureaucracy and the
outside ones it constantly fights, NASA simply finds it impossible to
do anything simply and quickly.  When missions take a decade to mount,
they *will* be big and complicated, no matter where they are going
or what booster they ride.  Cassini, planned from the start for an
expendable launch, will be every bit as bloated as Galileo, since none
of the people involved believe they'll get another Saturn mission in
their working lifetimes.  *That* is the real problem.
--
1755 EST, Dec 14, 1972:  human |     Henry Spencer at U of Toronto Zoology
exploration of space terminates| uunet!attcan!utzoo!henry [e-mail]

------------------------------

End of SPACE Digest V10 #332
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