Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT_ZIP/spacedig/V10_3/V10_330.ZIP/V10_330

Internet Message Format | 1991-07-08 | 13KB

Return-path: <[e-mail]>
X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson
Received: from beak.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr11/tm2b/space/[e-mail] (->+dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl) (->ota+space.digests)
          ID </afs/andrew.cmu.edu/usr1/ota/Mailbox/UZUTQsS00VcJQIj04h>;
          Sun, 10 Dec 89 01:27:04 -0500 (EST)
Message-ID: <[e-mail]>
Reply-To: [e-mail]
From: [e-mail]
To: [e-mail]
Date: Sun, 10 Dec 89 01:26:42 -0500 (EST)
Subject: SPACE Digest V10 #330

SPACE Digest                                     Volume 10 : Issue 330

Today's Topics:
    Observing the bright ones (was: Tracking Military Satellites)
               Re: Mars rovers
        Re: Manned vs Unmanned Mission to Mars
     Please Remove me from the Space Digest Mailing List
             Fund-raising via public plea
               Reminders for Old Farts
           Martian rover on remote control
            Could we knock it off?
----------------------------------------------------------------------

Date: 8 Dec 89 22:22:25 GMT
From: pikes!udenva!isis!scicom![e-mail]  (Bruce Watson)
Subject: Observing the bright ones (was: Tracking Military Satellites)


Next week's installment of PBS's NOVA investigates "How English schoolboys
and two teachers located a secret Soviet space center in 1966."
Check your local listings.

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

Date: 9 Dec 89 21:51:01 GMT
From: jumbo![e-mail]  (Jorge Stolfi)
Subject: Re: Mars rovers

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?  Such a trip would make an
absolutely fantastic science mission.  And yet this is not an
unrealistic goal for an unmanned teleoperated rover, even with
today's technology and 20-minute delays.

Please note that such a trip would be *far* beyond the capabilities of
any manned rover that we could dream of sending, even in a $400Bi
mission.  To begin with, a manned rover has to come back to the landing
site; that alone cuts its range in half.  A manned rover needs to be
pressurized and heated, and must carry enough food, water, oxygen, etc.
to last for the whole trip.  That means not only a heavier vehicle but
also a lower payload/deadweight ratio.  A manned rover will probably
have to use wheels rather than legs, which would probably restrict the
kind of terrains it could handle.  Increased weight and wheel
propulsion require a more powerful motor and a heftier energy source;
which means solar cells and RTGs are out, leaving only only fuel cells
or combustion engines (and lots of carry-on fuel), or perhaps a nuclear
reactor (and lots of shielding).  Finally, a manned rover needs to be
designed more conservatively than an unmanned rover, which means still
more dead weight and *lots* more money.

>   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.
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.  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.

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?

    Jorge Stolfi ([e-mail], ..!decwrl!stolfi)
------------------------------------------------------------------------
    But before they did that, they had to load the vehicle-projectile
    with all the things they needed for the trip.  And these were
    numerous.  If Ardan had his way entirely, there would have been no
    space left for passengers.
      --Verne, _From the Earth to the Moon_ (1865)

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

Date: 9 Dec 89 22:52:57 GMT
From: cs.utexas.edu!usc!jarthur![e-mail]  (David L. Williamson)
Subject: Re: Manned vs Unmanned Mission to Mars


Dear Jim Bowery,
    You, sir, are easily one of the most backward people I have ever
communicated with.  The drivel that you spill all over the net is usually
emotional garbage about how you are always correct and anybody who opposes
you is a crying imbecile.
    Thank you very much for your viewpoint.  You are free to say what
you wish, but I am also free to ignore everything you say.  You are becoming
part of my permanent KILL file, and I suspect that you will receive the same
treatment from many others as well.
                        Sincerely,
                        David L. Williamson

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

Date: 9 Dec 89 22:59:30 GMT
From: vax5![e-mail]
Subject: Please Remove me from the Space Digest Mailing List

To whom it may concern:

Please remove me from the Space Digest Mailing List.  Thank you.

Eric Weisstein
[e-mail]

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

Date: 9 Dec 89 18:43:26 GMT
From: zaphod.mps.ohio-state.edu!wuarchive!kuhub.cc.ukans.edu![e-mail]
Subject: Fund-raising via public plea

Nick Szabo writes:
>For any multi-billion dollar fund-raising, one or more of the following
>must occur:

>a) millions of people (or a lesser number of rich people) must share a
>common interest in the project, strongly enough to donate billions of
>dollars (this has never happened in world history).

Actually, if I remember correctly, that kind of money (in relative terms) was
raised not once but twice for the Statue of Liberty. Back in the late 1800's
quite a bit of money was raised to build the pedestal the statue was going to
stand on, and then in the 1980's a lot of money was raised for its restoration.
The general public will make contributions if the cause is worthy (in their
opinion) and well-publicized... I believe there are several hundred thousand
space enthusiasts (those who take the time to join an organization or do
something, like going to watch a launch) who would contribute, plus possibly
millions more who would be willing to contribute. How many people were there
for the first shuttle launch after the Challenger disaster? I remember for sure
that it was a record, and I think it was well over a million people...

Travis Butler                    Argue ideas, not sources.
University of Kansas, Lawrence   [e-mail]

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

Date: Sat, 9 Dec 89 04:00:22 PST
From: Eugene Miya <[e-mail]>
Subject: Reminders for Old Farts

Hints for old users (subtle reminders) You'll know these.

Minimize cross references, [Do you REALLY NEED to?]
Edit "Subject:" lines especially if you are taking a tangent.
Send mail instead, avoid posting follow ups. [1 mail message worth 100 posts.]
Read all available articles before posting a follow-up. [Check all references.]
Cut down attributed articles.  Summarize!
Put a return address in the body (signature) of your message (mail or
article), state institution, etc. don't assume mail works.
Use absolute dates.  Post in a timely way.  Don't post what everyone will
get on TV anyway.
Some editors and window systems do character count line wrapping:
please keep lines under 80 characters for those using ASCII terms (use <CR>).

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

Date: 9 Dec 89 17:36:23 GMT
From: zaphod.mps.ohio-state.edu!swrinde!cs.utexas.edu!jarvis.csri.toronto.edu!helios.physics.utoronto.ca!physics.utoronto.ca![e-mail]  (Christopher Neufeld)
Subject: Martian rover on remote control


   One other potential problem with teleoperated martian rovers hasn't been
mentioned here. Assuming that the rover lands, leaving an orbiter to act as
a relay station, what fraction of the time spent on Mars can actually be
used for "real-time" control? Consider: if the rover cannot receive
messages directly from Earth but has instead to receive boosted signals
from the orbiter, then the rover will not be usable for at least half of
the time there, while the orbiter is below the horizon.
   If the rover can receive direct signals, it can't get them when the
earth is below the horizon and the orbiter is below the horizon or eclipsed
from the Earth by Mars.
   What is the fraction of the year for which Mars lies too close to the
Sun, or behind the Sun, for direct communications to be possible?
   Is there a problem with the Moon eclipsing Mars?
   What about the famous sandstorms? Can the rover receive transmissions
from the orbiter when ferrous dust is blowing around? Even upper atmosphere
clouds could interfere though they don't affect the rover directly.
   It seems to me that the previous estimates of distance covered per day
by the teleoperated rover would have to be reduced by at least 75% if it
requires a working communication link to Earth to move safely.
   To throw some facts into the discussion, what about the Viking landers?
When somebody on the ground decided he wanted the lander to take a sample
of soil from a certain location, what was the average time before the
lander acted on the information and reported it was starting the job?
--
 Christopher Neufeld....Just a graduate student  | "In another reality,
 [e-mail]              | I might have called you
 [e-mail]                    | 'friend'."
 "Don't edit reality for the sake of simplicity" |   _Balance of Terror_

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

Date: 9 Dec 89 18:44:14 GMT
From: zaphod.mps.ohio-state.edu!wuarchive!kuhub.cc.ukans.edu![e-mail]
Subject: Could we knock it off?

There have been a lot of insults running around the newsgroup recently:

Jim Bowery writes:
>ready to retire.  Sorry Kieran -- better stop sucking blood out of that
>vein -- the host is almost dead.  No self-respecting parasite kills
>its host.
...
>Asking that I be very very precise in these definitions is your way of
>trying to get away with being a tit-sucking brat.  I only become insulting
>to people who are attempting to remain infantile at the expense
>of everyone else, when they should have grown up a long time ago.

Kieran A. Carroll writes:
>Anyway, what's your point, Jim? (Do you have a point, Jim?) Are you arguing
...
>out at? If so, then >explaining< it would contribute a lot more to the
>discussion, than would posting endless insulting replies.

<next set of replies>
>Gee, Jim, but you're insulting to almost everyone on the net,
>as far as I can tell. Has it ever occurred to you that maybe what's
>at fault is >your perception< of other people? You know, you've said all
>kinds of insulting things about me, based on assumptions about what I
>do for a living, but >you don't know< what I do for a living. Doesn't
>that strike you as embarrassing? (especially as your guesses missed the
>mark pretty badly...)

Dale M. Greer writes:
>This is a prime example of the accute egocentrism from which most of
>the boys contributing to the Space Digest seem to be suffering.  The
>repeated use of "we" where "I" would be more appropriate suggests
>that perhaps they need to put down their sci-fi books once in a while,
>get away from their computers occasionally, go out and meet some people,
>try to meet some girls.

John L. McKernan writes:
>On a more personal note: the insulting tone of your posting suggests that
>if you are concerned about personality problems, you should look closer
>to home.

Please, people. I've only been around the net for a few months, but I've been
using local BBS systems for over five years. The only thing I've ever seen come
from these kind of insults is more insults, and the group as a whole suffers.
If you don't agree with someone, say so, but let's not get into personal
attacks, OK? Just because someone's ideas don't fit your world view doesn't
mean they are "infantile," or that you should be insulting in return.
Let's cool it, everybody. Name-calling should have gone out in grade school.

Travis Butler                    Argue ideas, not sources.
University of Kansas, Lawrence   [e-mail]

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

End of SPACE Digest V10 #330
*******************