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Subject: SPACE Digest V12 #445

SPACE Digest                                     Volume 12 : Issue 445

Today's Topics:
            Re: Manned/unmanned tradeoffs
              Magellan Update - 10/02/90
            Re: Manned/unmanned tradeoffs
              Re: Launch cost per pound
      Re: Time delay (was Re: Manned/unmanned tradeoffs)
           Re: disposal of N-waste into sun
     Re: Lifeless interplanetary travellers - where are they now?
             Article on NASA in Economist
              Magellan Update - 10/03/90
              Magellan Update - 10/10/90
                Re: Space GIFs

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

Date: 4 Oct 90 02:58:10 GMT
From: media-lab![e-mail]  (Marvin Minsky)
Subject: Re: Manned/unmanned tradeoffs


[e-mail] (Roger Dubbs) says,

> But are you sure about just what kinds of speeds are involved in
> space operations?  Actually, the overall time constant of the system
> is dependent on many factors, not just the speed.  The fact is, some
> serious analysis of the particular job to be tele-operated is
> required.  I doubt whether the time constant of the system would be as
> large as a tanker or as small as an F-16.  This discussion is
> meaningless unless you know about the particular system to be
> controlled.

Yes, I am sure.  Generally, the speeds of space-station operation can
be lower than any earth operations, unless someone has equipped the
lab with things that operate too fast.  A few operations cannot be
slower than the order of 90 minutes, because some things must be done
in orbital time.  You're overlooking how many earth-jobs require
"real-time" operations like catching things before they fall, only
because of gravity.  Most Space-lab operations could be done at slower
than tanker speeds.  Can you really think of station-keeping
operations that really must be done in less than seconds?  Please
remember, I talking about the enormous value of using remotely-manned
operation in GEO and lunar operations.  Not on Mars or Jupiter.  And
we're not talking off-hand options, but of doing more with 1 billion
dollars this way than with, say, 30 B by using Space Station Freedom
with its ill-equipped human crew.

> IMHO, the most versatile tool man has is man.  We will never really
be able to exploit space until we have a permanent manned presence
there.  Man can adapt to situations that tools could never hope to.
The scientists wish that more money could be spent on probes, rather
than expensive manned space programs.  IMHO, once we have a large
presence of humans in space, the probes will be trivial to launch and
maintain.  Further, when we actually visit places that probes have
gone before, we are bound to learn much more about the place than
probes could tell us.

Nonsense.  With a few years R&D, the most versatile tool we'll have is
telepresence.  Robots can adapt to conditions men can never.  Let's be
realistic.  And stop confusing robotic probes with remotely-manned
instruments, which carry the human judgment with them.

Think of teleoperators as like shoes.  And of space as like walking on
ice or on coals.  Simple as that.  Your brain is still there -- but not
your weak, slow, greedy, fragile body.  Think of the remote cameras as
like microscopes and telescopes attached to your eyes.

Let's drop outworn emotional metaphors.  The most versatile tools man
has are are his tools!

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

Date: 2 Oct 90 22:48:10 GMT
From: elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Magellan Update - 10/02/90


                     MAGELLAN STATUS REPORT
                         October 2, 1990

     The Magellan spacecraft has acquired about 125 orbits of
Venus radar mapping data since mapping officially began on Sept.
15.  When mosaicked, the wedge-shaped area of imagery would
cover on Earth a stretch across the southern United States from
Los Angeles to nearly the coast of South Carolina, and from the
North Pole to almost the South Pole.  The DSN (Deep Space Network)
acquisition of the radar data has averaged 98.9 percent.

     A spacecraft anomaly investigation review was held in
Denver on September 27. Review board members said additional
heartbeat modifications are being studied to facilitate mapping
through an AACS (Attitude and Articulation Control Subsystem)
glitch. These are planned to be implemented in December. By the
end of January 1991, the flight controllers will try to
implement an interim fix to the AACS B-side memory to make it
usable.

     The long term memory-B fix is targeted to be completed as
early as June 1 of next year, but it could take as long as to
the end of the year. The long-term fix also will incorporate
software modifications to guard against computer glitches.

     Most investigations as to the primary cause of the August 16
loss of signal are being closed out. The actual cause has not
been found, but several candidates have been eliminated.
      ___    _____     ___
     /_ /|  /____/ \  /_ /|
     | | | |  __ \ /| | | |      Ron Baalke         | [e-mail]
  ___| | | | |__) |/  | | |___   Jet Propulsion Lab | [e-mail]
 /___| | | |  ___/    | |/__ /|  M/S 301-355        |
 |_____|/  |_|/       |_____|/   Pasadena, CA 91109 |

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

Date: 3 Oct 90 18:24:36 GMT
From: wuarchive!cs.utexas.edu!helios!neural![e-mail]  (Roger Dubbs)
Subject: Re: Manned/unmanned tradeoffs

[e-mail] says,

> Trains and tankers have large time constants (in other words, they
>don't accelerate quickly), but there's nothing inherently difficult
>about controlling such systems ('plants' in control systems jargon).

> Time delays in the control input, on the other hand, particularly when
>they are not small relative to the dominant plant time constants, can
>be destabilizing.

> In other words, a 2.5 s delay isn't a problem for a tanker, but you
>wouldn't want to fly in an F-16 whose pitch axis control system had
>one....

[e-mail] (Marvin Minsky) responds:

>This is confusing different things.  Presumably, you could fly an
>F-16, in spite of delay -- if you could maintain low speeds.  You
>can't, because of gravity.  The problem of "real-time control", here
>is not involved with how FAST you can accelerate, but with how low you
>can keep your -- and how SLOW you can accelerate.  The issues about
>time delay are, thus, much more involved with speeds rather than
>accelerations.  Planes have minimum speeds, hence each delay implies a
>minimum reaction-distance.  But that has little to do with spaceships,
>or earth-ships.  Tankers can be "flown" as slow as you want, hence
>have no problems with time delay, for well-trained pilots.

But are you sure about just what kinds of speeds are involved in space
operations?  Actually, the overall time constant of the system is
dependent on many factors, not just the speed.  The fact is, some
serious analysis of the particular job to be tele-operated is required.
I doubt whether the time constant of the system would be as large as a
tanker or as small as an F-16.  This discussion is meaningless unless
you know about the particular system to be controlled.

IMHO, the most versatile tool man has is man.  We will never really be
able to exploit space until we have a permanent manned presence there.
Man can adapt to situations that tools could never hope to.  The
scientists wish that more money could be spent on probes, rather than
expensive manned space programs.  IMHO, once we have a large presence of
humans in space, the probes will be trivial to launch and maintain.
Further, when we actually visit places that probes have gone before, we
are bound to learn much more about the place than probes could tell us.

                            Roger Dubbs

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

Date: 5 Oct 90 16:18:59 GMT
From: news-server.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Launch cost per pound

In article <[e-mail]> [e-mail] (Doug Mohney) writes:
>>Space is expensive because of NASA's and the government's monopoly on the
>>facilities. If it became cheap, that would threaten NASA's turf which it
>>doesn't want. It suits NASA's purpose to keep space expensive so it should
>>be no suprise that it is.
>
>You make it sound like a conspiracy to keep space expensive. I find THAT hard
>to swallow, since it is in NASA's best interest to to DELIVER on their previous
>claims of cheap payload-to-orbit, rather than being cheap-shot'ed

It's not a conspiracy, just a situation where it's in almost everyone's
interest to maintain the status quo.  NASA is no longer promising cheap
launches and no longer has to worry about being criticized for the lack
thereof.  I don't think one has to invoke turf protection in quite the
way that Allen did, though; it suffices that NASA in particular and the
government in general want *control* of space activity, which means they
want control of launch operations... and government-controlled operations
are never cheap.
--
Imagine life with OS/360 the standard  | Henry Spencer at U of Toronto Zoology
operating system.  Now think about X.  |  [e-mail]   utzoo!henry

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

Date: 5 Oct 90 15:58:11 GMT
From: news-server.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Time delay (was Re: Manned/unmanned tradeoffs)

In article <9010041933.AA14633@tilde> [e-mail] (If Clayton's an Aggie, I'm not!) writes:
>As far as training goes, even a trained operator will need to adaptation time
>when coming "on shift."  And this person could be deadly on the street, trying
>to anticipate and react in a different time frame from work.
>
>Maybe the time delay problem can be licked, but it won't be all that easy.

At risk of repeating myself and spoiling a beautiful argument with ugly
facts, teleoperation of simple equipment with a 2.5s delay *has been tried*
experimentally (by the Space Studies Institute) and *is not that hard*.

Mind you, it depends a lot on what sort of work you are trying to do with
teleoperation, and this in turn influences how you design missions.  Running
a bulldozer (which is roughly what SSI tried) is one thing.  Assembling
electronic equipment is another.  Juggling eggs is yet another. :-)  There
is enough experimental evidence to confidently say that teleoperation for
simple tasks, as a *supplement* to manned presence, is feasible at lunar
distances:  human bulldozer operators need not be on the spot, although
the bulldozer repairman may be a different story.

Quick response to real-time problems is obviously difficult.  The answer
is to structure the job so that it isn't necessary.  Here again, this
has implications for mission design:  driving a bulldozer around a base
should be okay, but driving a science rover over unknown terrain, with
no on-the-spot human help available should trouble develop, will be trickier.
--
Imagine life with OS/360 the standard  | Henry Spencer at U of Toronto Zoology
operating system.  Now think about X.  |  [e-mail]   utzoo!henry

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

Date: 10 Oct 90 15:21:46 GMT
From: voder!dtg.nsc.com![e-mail]  (Alan Hepburn)
Subject: Re: disposal of N-waste into sun

In article <[e-mail]> [e-mail] writes:
>
>Do the arithmetic on dissolving the "high grade" waste in a suitable
>solvent and then dispersing it over a few square miles of ocean.  I
>think you will find it disappears into the background.  It is high
>grade only because the ecohysterics have insisted on concentrating
>it into minimum volume.
>
>dan herrick


Picture this:  a supertanker modified slightly so that the nuclear
waste starts out in the bow tank, being diluted 100:1 with sea water.
This mix is then pumped to the next tank where it is diluted 100:1 with
sea water.  And so on till the last tank, which is pumped into the open
ocean.  You would be unable to detect other than background radiation
in the resulting water.





--
Alan Hepburn                 "History is a lie agreed upon."
mail: [e-mail]        Voltaire

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

Date: 10 Oct 90 17:30:24 GMT
From: usc!cs.utexas.edu!news-server.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Lifeless interplanetary travellers - where are they now?

I wrote:
>... Failing that, it would return to Earth's orbit, but the odds are
>roughly zero that Earth would be nearby at the time -- Earth's orbit is
>half a billion kilometers long.

How embarrassing; not half a billion, but a full billion.

What's a factor of two between friends? :-)
--
Imagine life with OS/360 the standard  | Henry Spencer at U of Toronto Zoology
operating system.  Now think about X.  |  [e-mail]   utzoo!henry

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

Date: 10 Oct 90 20:14:07 GMT
From: bacchus.pa.dec.com!jumbo!jumbo![e-mail]  (Bob Ayers)
Subject: Article on NASA in Economist

The Economist magazine of 29sep-5oct has an excellect article on NASA and
its rpoblems. An excerpt:

    By 1975, NASA's budget was a third of what it had been ten years
    earlier. NASA responded to starvation the way most creatures do; it
    lost a lot of weight and developed a monomaniacal interest in its next
    meal. In the 1970s, the next meal was the space-shuttle programme.

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

Date: 3 Oct 90 23:49:15 GMT
From: sdd.hp.com!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Magellan Update - 10/03/90


                     MAGELLAN SPECIAL REPORT
                         October 3, 1990

     A loss of power at the Deep Space Network (DSN) station near
Madrid, Spain, resulted in loss of radar data reception of one-half
of orbit 490 and all of the mapping data from orbit 491.

     A bad star calibration on orbit 493 caused a shift in the HGA
(High Gain Antenna) pointing of approximately half a degree which
severely degraded the downlink during playback of the second half
of orbit 493 and the first half of orbit 494.

     Additionally, radar data was taken on orbit 494 with the
HGA mispointed by half a degree. Some or all of that data may be
salvaged by special processing.

     Steps were being taken to limit the size of star calibration
updates to prevent bad updates from mispointing the antenna.

     The orbits are counted from August 10 when Magellan went into
orbit around Venus. An orbit takes three hours and 15 minutes and
there are seven and a third orbits a day.
      ___    _____     ___
     /_ /|  /____/ \  /_ /|
     | | | |  __ \ /| | | |      Ron Baalke         | [e-mail]
  ___| | | | |__) |/  | | |___   Jet Propulsion Lab | [e-mail]
 /___| | | |  ___/    | |/__ /|  M/S 301-355        |
 |_____|/  |_|/       |_____|/   Pasadena, CA 91109 |

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

Date: 10 Oct 90 21:39:34 GMT
From: swrinde!zaphod.mps.ohio-state.edu!sdd.hp.com!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Magellan Update - 10/10/90


                         Magellan Status Report
                           October 10, 1990

     The Magellan spacecraft has now completed 184 mapping orbits, with
good radar data received from at least 180 orbits.  The seven star
calibrations and two desaturations of the reaction wheels in the past 24
hours were successful with nominal attitude updates.  Once star calibration
was partially successful.

     The 8 day mapping upload M0283 was sent to the spacecraft yesterday and
is now executing.  Engineering telemetry shows the radar sensors continue
to operate normally.  A test image swath from orbit 534 was produced and
confirmed satisfactory the end-to-end system performance.  Production of
standard image products through the SAR (Synthetic Aperture Radar)
processor has started.  Twelve image swaths covering the reproccessing of
orbits 376 through 387 were successfully completed yesterday.
      ___    _____     ___
     /_ /|  /____/ \  /_ /|
     | | | |  __ \ /| | | |      Ron Baalke         | [e-mail]
  ___| | | | |__) |/  | | |___   Jet Propulsion Lab | [e-mail]
 /___| | | |  ___/    | |/__ /|  M/S 301-355        |
 |_____|/  |_|/       |_____|/   Pasadena, CA 91109 |

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

Date: 10 Oct 90 06:58:58 GMT
From: sumax!polari![e-mail]  (Paul Varn)
Subject: Re: Space GIFs

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

From: @polari (Don Wennick)
Date: Tue, 9 Oct 90 00:31:56 PDT
X-Mailer: Mail User's Shell (6.5.6 6/30/89)
To: [e-mail]


In article <[e-mail]> you write:
>Since my orriginal request for a source of space related GIF format pictures,
>there has been mail sent to me by others interested in the same thing.

Following is a response I recieved from a local user.  I've fowarded it in
hopes it will help others who seek the same information as myself.

There is an e-mail ftp server that I use occasionally. This allows access to
any anonymous ftp site, or any other ftp site you have a valid account
on. wuarchive.wustl.edu is accessible this way. The server's address
is [e-mail], and you can get the instructions for it's
use by sending e-mail with the command 'help' in the message body.
I don't know if a .signature will confuse it, but I never allow mush to
sign my messages to any servers.

Don.

---
Don Wennick | [e-mail] -or- [e-mail]
"subhuman bloodless leaders fed on lies and fear / and TV anchor news teams
 trim all we see and hear / use your head / sidestep the traps / snake
 through the chaos with a smooth noodle map" - Devo

-PV-
     /+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+\
     +   COMMENTS COMPLIMENTS CONTINOUS COMPLAINTS   +
     "             COURTESY: Paul Varn               "
     +   UUCP: pv@polari             GEnie: p.varn   +
     \+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+/

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

End of SPACE Digest V12 #445
*******************