Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/spacedig/v13_2/v13_211.txt

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Subject: SPACE Digest V13 #211

SPACE Digest                                     Volume 13 : Issue 211

Today's Topics:
             Re: Terraforming, sun shield
             Re: NASA technology choices
              Re: Japan's Space Industry
        Re: Can Mars moons be seen from Mars?
              Magellan Update - 02/27/91
          Can Mars moons be seen from Mars?
             Re: Terraforming, sun shield
         Re: Whither Lunar Observer in FY92?
      Re: Why bother? (was Re: Terraforming, sun shield)
              Re: Space Profits

Administrivia:

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

Date: 25 Feb 91 19:47:30 GMT
From: swrinde!zaphod.mps.ohio-state.edu!uakari.primate.wisc.edu!aplcen!warper.jhuapl.edu![e-mail]  (Ray Sterner)
Subject: Re: Terraforming, sun shield

[e-mail] (Jonathan Leech) writes:

>    I dug out my copy of Oberg's _New Earths_ (Stackpole 1981; ISBN
>0-8117-1007-6) just now.  The approach he advocates is a little
>different from what we've been talking about: rather than removing the
>atmosphere mechanically or binding it to rock, he wants to import H2
>from Saturn to turn it into water.

  Sounds like a possible application for a neutral particle beam, with
  a ballistic trajectory from an outer planet to Venus.  Only a fraction
  (maybe 0) would stay neutral and make it to Venus, since the beam
  would be fighting its way against the solar wind (which probably
  dumps more hydrogen onto Venus than the beam would anyway).

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

Date: 26 Feb 91 19:26:15 GMT
From: swrinde!cs.utexas.edu!news-server.csri.toronto.edu!utzoo![e-mail]  (Kieran A. Carroll)
Subject: Re: NASA technology choices

> Nick Szabo ([e-mail]) writes:
>
> In article <[e-mail]> [e-mail] writes:
> >As a matter of a fact the Flight Telerobotic Servicer bears more
> >than a passing resemblance to a Discovery pod; it's just squashed
> >because it doesn't have a person inside.  After all, if you're
> >going to restrict your dexterity to that available with waldos,
> >then there's no point in adding life-support; just use teleoperation
> >from the space station (no communication delay there), you're not
> >losing a thing.
>
> Or just do teleoperation from earth (with a good circuit there is no
> large communications delay).

For the type of teleoperation that was planned for FTS (force-reflecting
master-slave set-up), it has been shown that closed-loop time-delay of greater
than about 10 milliseconds cannot be tolerated. Research done several years
ago at JPL, in support of FTS design, showed that the closed-loop system
starts to go unstable for larger time delays. I imagine that this could be
ameliorated by increasing the time-constant of the joint controllers
of the robot, but this would make the manipulators more "sluggish",
which causes operator fatigue to increase significantly.

The FTS teleoperation concept is on the leading edge of the "telepresence"
school of teleoperation, in which the sensors and actuators are set up
to try to fool the operator's perceptions into believing that s/he is
actually at the remote location. It is an outgrowth of the work at
Oak Ridge National Laboratories, where force-reflecting master-slave
teleoperation was developed during WWII, for remote handling of radioactive
materials under the Manhattan District project. It is related to the
"exoskeleton" projects of the '50's and '60's, which also foundered on the
rocks of closed-loop instability.

Another paradigm for teleoperation is used for controlling the Canadarm
(NSTS RMS, for you Yanks :-). Instead of using a force-reflecting
manipulator arm as an input device to specify the desired location/orientation of
the end-effector of a manipulator, the operator here uses a pair of
joysticks to specify the desired >velocity< (translational and rotational)
of the end-effector. These may be referred to either an end-effector-fixed
coordinate frame, or a "world-fixed" one ("resolved rate" control).
The historical background for this controller is industrial robot control,
rather than teleoperation.

These velocity commands are forwarded to joint-level controllers in the
manipulator, which use them as set-points for individual joint PID
controllers (typically). The feedback loop is closed not by force-reflection,
but by the operator observing the motion of the end-effector (or payload),
either directly or via TV cameras.

This method has the advantage of allowing much longer closed-loop delay times
without instability. While FTS could not be operated from the ground
(where the closed-loop delay could approach 250 milliseconds), a properly-
designed commanded-rate controller with TV-camera feedback could
do the job (as long as a reliable communications link existed). Work
in Canada is proceeding to generalize this concept in ways that would
allow it to be used to perform Earth-based teleoperation of devices on the
Moon; one step in accomplishing this is to build some autonomy into the
lower-level control loops, with periodic (time-delayed) "supervision"
coming from the Earth.

Credit where due dept.: the RMS control design concept originated
in the US (at JSC, I believe). The adaptation of Canadarm control concepts
to add greater autonomy relies to some extent on work done either at NASA,
or by NASA contractors under the FTS program.

Final Note: has anyone heard what the actual status of FTS is? I've heard that
it's not been cancelled, but just transferred from the SSF program to
a separate development program -- i.e. it's not part of the space station
anymore, but it's still being worked on. Any other news?
--

     Kieran A. Carroll @ U of Toronto Aerospace Institute
     uunet!attcan!utzoo!kcarroll [e-mail]

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

Date: 27 Feb 91 19:46:45 GMT
From: rex!rouge![e-mail]  (Fraering Philip)
Subject: Re: Japan's Space Industry

In article <[e-mail]> [e-mail] (Paul Blase) writes:

>WRONG!!! The Japanese ARE spending serious money on the subject.  They
>intend to MAKE A PROFIT!!!!!!!!! (at our expense).


Funny, when BP goes into the wilds of some desolate Middle Eastern
country and drills a well, noone talks about how they are making a
profit at Chinese expense. You see, as I detailed a while back on this
group, the medieval Chinese invented the oil/natural gas "drilling"
rig. They were used to extract brine from deep below the ground, and
natural gas was used to boil the brine. They used a percussion bit,
variations of which (just as a stupid American could claim that all
the Japanese stuff is only variations of ours) were used when the U.S.
went from using the stuff oozing out of a dead whale and using
petroleum instead. The modern rotary bit was invented by Hughes, but
by the time the Japanese presense in space is 10 years old they will
be using Japanese technology.

BTW, most people don't think of the West and Japan as having stolen
the technologies that helped start the Industrial Revolution from
China. Most people look at the massive floods and famines of 19th
century China and wonder why they didn't _do_ anything about it, such
as moving from an agrarian to an industrial economy if they were able.

Phil Fraering
[e-mail]
"I'm troubled, I'm dissatisfied, and I'm Irish." Marianne Moore

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

Date: 27 Feb 91 23:17:41 GMT
From: usc!cs.utexas.edu!news-server.csri.toronto.edu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Can Mars moons be seen from Mars?

In article <[e-mail]> [e-mail] (Eric J. Korpela) writes:
>Oops!  Make that at least three.  It may be possible for those with good eyes
>to separate the outer galilean satellites from Jupiter...

There have been anecdotal reports of it being just possible from Earth
for people with superb eyesight under extremely good conditions, I believe.
From Mars the chances are better.
--
"But this *is* the simplified version   | Henry Spencer @ U of Toronto Zoology
for the general public."     -S. Harris |  [e-mail]  utzoo!henry

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

Date: 28 Feb 91 03:14:33 GMT
From: usc!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Magellan Update - 02/27/91


                        MAGELLAN STATUS REPORT
                           February 27, 1991

     The Magellan spacecraft and its radar system are performing nominally.
All STARCALS (star calibrations) and DESATS (desaturations) during the past
24 hours were successful with attitude updates averaging 0.056 deg.

     The M1058 command sequence was sent to the spacecraft and is presently
executing.  It includes the solar panel offpoint and 10 minute early turn
from mapping in order to maintain spacecraft temperatures at acceptable levels.

     DMS-A (Data Management Subsystem) Test #3, the playback of stored
data patterns, will start near the end of orbit #1591 this morning and
continue through orbit #1602 tomorrow evening.  The gyroscope temperatures
have been declining, with a peak at 68 degrees C.

     Spacecraft controllers believe that they are already seeing the effects
of solar occultation as measured by the solar panel output.  Navigation
predicted that the spacecraft would first encounter the shadow of Venus early
tomorrow morning, so we are probably observing the effects of Venus'
atmosphere.  The effects are seen for as much as six minute per orbit.
      ___    _____     ___
     /_ /|  /____/ \  /_ /|      Ron Baalke         | [e-mail]
     | | | |  __ \ /| | | |      Jet Propulsion Lab | Is it mind over matter,
  ___| | | | |__) |/  | | |___   M/S 301-355        | or matter over mind?
 /___| | | |  ___/    | |/__ /|  Pasadena, CA 91109 | Never mind.
 |_____|/  |_|/       |_____|/                      | It doesn't matter.

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

Date: 27 Feb 91 08:58:23 GMT
From: mcsun!ukc!newcastle.ac.uk![e-mail]
Subject: Can Mars moons be seen from Mars?

Are the moons of Mars both large enough so that they can be seen (by eye, not
by telescope)  from the Martian surface?
From the surface of which planet would the most moon's be visible to the unaided
observer?
        Earth = 1  (luna)
        Pluto = 1?
        Mars  =?
Venus, Mercury,gas giants =0

.................................................................
Department of Process and Chemical Engineering,  +
Newcastle University, United Kingdom.            + "If we breed like rabbits,
                                                 +  in the long run we have
JANET: [e-mail]                 +  we have to die like
UUCP : ...!ukc!newcastle.ac.uk!W.P.Coyne         +  rabbits" Carlson on
ARPA : [e-mail]                 +  population growth.
................ ................................+.......................

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

Date: 27 Feb 91 17:58:38 GMT
From: bonnie.concordia.ca!ccu.umanitoba.ca![e-mail]
Subject: Re: Terraforming, sun shield

In article <[e-mail]> [e-mail] (David Fuller) writes:
>I find the concept that humans find "uninhabited" planets fertile ground
>for cultivation repulsive, ignorant and a propulsion of the status quo.
>
>Without understanding the greater nature of the universe, we propose to
>make a planet habitable inasmuch as sticking some giant terrestrial penis
>into Venus' vagina without understanding in any real sense why
>Venus is there or whether there is something more subtle to be learnt.
>
>We may get older as a (male) race but we certainly don't get any
>smarter.

I could argue that there is a VERY compelling reason for terraforming other
planets as soon as possible: the apparent scarcity of intelligent life in the
galaxy.

We know very little about the prevalence of extraterrestrial life. Perhaps
the only thing we do know with certainty is that intelligent life (as
defined by the production of artificial radio communications) is
exceedingly rare.

Knowing how difficult it is for life to originate (and how few planets are
likely to have the right conditions), and how apparently rare intelligent
life is, it is justifiable to say thet life is the most precious (valuable)
thing in the universe, and intelligent life the most rare and precious of
all. Since our biosphere is the only known example of life, and man the
only known "intelligent" species, we should be compelled to safeguard  this
resource by re-creating it on other planets. Indeed, all commercial
considerations aside, this may be the single most important justification
for proceeding with space exploration and development.

Balls of gas and rock are probably more numerous than the stars. Until
proven otherwise, we must assume that life is more rare than hydrogen
in the interstellar vacume.

===============================================================================
Brian Fristensky                | What can literature do against the pitiless
Department of Plant Science     | onslaught of naked violence? Let us not for-
University of Manitoba          | get that violence does not and cannot flourish
Winnipeg, MB R3T 2N2  CANADA    | by itself; it is inevitably intertwined with
[e-mail]          | LYING... Lies can stand up against much in
Office phone:   [phone]    | world, but not against art.
FAX:            204-275-5128    |     Alexander Solzhenitsyn, NOBEL LECTURE
===============================================================================

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

Date: 27 Feb 91 19:45:50 GMT
From: deccrl!news.crl.dec.com!shlump.nac.dec.com!sousa.enet.dec.com!sndpit.enet.dec.com![e-mail]  (Willie Smith)
Subject: Re: Whither Lunar Observer in FY92?


In article <[e-mail]>, [e-mail]
    (Henry Spencer) writes...
>In article <[e-mail]> [e-mail] (John A. Weeks III) writes:
>>No smiley here--I think it really is feasible to return a moon orbitor
>>back to Earth.  The big trick would be getting the probe back to into
>>Earth orbit so the shuttle can pict it up...
>
>That is indeed the big trick.

No, it's easy, you just collect it on a return trip from one of the
regularly scheduled supply runs to the lunar base, right?

Willie Smith
[e-mail]
[e-mail]
{Usenet!Backbone}!decwrl!sndpit.enet.dec.com!smith

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

Date: 26 Feb 91 16:28:23 GMT
From: usc!cs.utexas.edu!news-server.csri.toronto.edu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Why bother? (was Re: Terraforming, sun shield)

In article <[e-mail]> [e-mail] (S.S.Sturrock) writes:
>Nice idea this terraforming, why can't we make lots of new worlds for people
>to live on, then we don't have to worry about contraception, or the population
>problem, excellent plan guys.  We make a mega mess of this world, get all
>green and caring but still we don't consider the one all important green issue,
>our propensity to overpopulate....

You seem to think that terraforming has someting to do with overpopulation.
This is a curious assumption.

We will never be able to export population in sufficient numbers to avoid
having to deal with overpopulation here, regardless of whether there are
attractive places to go.  Too few people are willing to go and it is too
expensive to transport the ones who are.

The point of terraforming is diversity, and lifeboats, not replacement.
--
"But this *is* the simplified version   | Henry Spencer @ U of Toronto Zoology
for the general public."     -S. Harris |  [e-mail]  utzoo!henry

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

Date: 25 Feb 91 20:14:01 GMT
From: usc!hacgate!ashtate!dbase![e-mail]  (Michael Wallis)
Subject: Re: Space Profits

The likely first lunar export will be oxygen, mined from the soil, and used to
fuel ships on the Earth-Luna run. It's cheaper to refine and ship it to Earth
than to haul it up the gravity well from the surface.

There's also He3, the "miricle" fusion fuel. If it can be proven useable, the
helium export will be a very valuable contract.

The main thing, though, is that we won't know what's valuable until we're there.
Columbus sold Isabella on his voyage because of spices. What he gave Spain was
CONSIDERABLY more valuable, and could not have been predicted in 1491.

-------------------------------------------------------------------------------
Michael Wallis                          INTERNET:       [e-mail]
Computer Consultant                     CI$:            75470,1264
San Jose, CA,   USA                     bix:            mwallis

                   "I'd rather be building rockets!"
--
-------------------------------------------------------------------------------
Michael Wallis                          INTERNET:       [e-mail]
Computer Consultant                     CI$:            75470,1264
San Jose, CA,   USA                     bix:            mwallis

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

End of SPACE Digest V13 #211
*******************