Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V12_6/V12_658.TXT

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Subject: SPACE Digest V12 #658

SPACE Digest                                     Volume 12 : Issue 658

Today's Topics:
        Re: Translunar/interplanetary shuttle?
            Re: Planetary Society
           Re: ASTRO status at 4/16:00 MET
        UIT Status for 12/09/90 [1500 CST] (Forwarded)
              Magellan Update - 12/05/90
              Magellan Update - 12/10/90
              Magellan Update - 12/04/90
             Light years and such
Re: Who killed Nuclear Rockets? (was Re: The Next Ten Years In Space)

Administrivia:

    Submissions to the SPACE Digest/sci.space should be mailed to
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----------------------------------------------------------------------

Date: 5 Dec 90 17:20:39 GMT
From: elroy.jpl.nasa.gov!swrinde!zaphod.mps.ohio-state.edu!samsung!umich!sharkey!teemc!fmeed1![e-mail]  (Russ Cage)
Subject: Re: Translunar/interplanetary shuttle?

In article <[e-mail]> [e-mail] writes:
>As for the problem with the main engines (we've been told here that they are
>not restartable), would it be possible to use the extra fuel for the OMS
>engines instead...? (my guess is it won't be, anyway).

It would be easy to carry extra OMS fuel; it has been proposed
before, and I've seen depictions of orbiters with a rack of fuel
tanks taking up the back half of the cargo bay.

The problem is the low impulse of the OMS engines. To do a trans-lunar
injection burn, decelerate into lunar orbit, and burn again to return
to earth takes something like a million pounds of OMS fuel.  This is
about 20 Shuttle payloads worth.

Forget the idea of taking a Shuttle orbiter to the moon.  It's stupid.

Consider that the weight of the Shuttle's wings, tail, engines, landing
gear, thrust structure and thermal protection system is probably 130,000
of its 160,000 lbs weight.  Eliminate that and you've cut the fuel
requirements by 4/5.  Then dump the OMS engines and their fuel, and
carry a single RL-10 engine burning hydrogen and oxygen.  (These ARE
restartable, and have never failed to start or restart.)  This cuts
the required fuel drastically, and the cost of launching it.  What
you wind up with would be much smaller and cheaper than a Shuttle
orbiter for the same payload, and it could be built of off-the-shelf
engines and other parts.
--
Russ Cage    Ford Powertrain Engineering Development Department
Work:  itivax.iti.org!cfctech!fmeed1!cage   (CHATTY MAIL NOT ANSWERED HERE)
Home:  [e-mail]  (All non-business mail)
Member:  HASA, "S" division.

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

Date: 9 Dec 90 04:29:04 GMT
From: zephyr.ens.tek.com!tektronix!sequent!crg5![e-mail]  (Nick Szabo)
Subject: Re: Planetary Society

In article <[e-mail]> [e-mail] (John Roberts) writes:


>If the Planetary Society wants to produce a consensus statement of people
>who hold a particular point of view, then fine. If they want to produce a
>statement and claim that it is the general consensus of everyone in the
>field, then they shouldn't make a deliberate effort to stack the meeting
>with people known to hold a particular point of view.

The Planetary Society never claimed the statement covers everybody in
the field.  They did not "stack" the committee any different than any
other committee.  The whole issue is a slander against the Planetary Society
and an ad hominem attack against this committee's conclusions.  It is
a sad sight to see a group that includes leaders of our successful exploration
of the solar system defamed like this.


>My own opinion is that the space station was in need of redesign, particularly
>in light of the predicted need for maintenance during assembly. I would also
>consider at least the option for use as an assembly point for lunar and
>interplanetary craft to be very important.

The *concept* of a space station needs redesign.  NASA has designed
and redesigned dozens of "space stations" since its inception and has only
a brief post-Apollo fling, ending in the sands of the Australian outback,
to show for it.  Maybe it's time we realized the whole aproach is wrong.


>Last I heard, the Planetary Society was still pushing for a hideously
>costly, crash-priority one-shot manned trip to Mars, mainly to serve
>as an inspiration to mankind and generate political goodwill

Good grief.  Everybody in the planetary science field knows this is
just a political ploy to get funding for the stuff that does the real
work, the probes.   There is no way anybody is going to afford to
send people to Mars or anywhere else beyond the Earth system until well
after it has been thoroughly explored and mapped.  But politics is
politics, and if NASA can conjure up space station "customers", the
planetary probe folks are entitled to conjure up a macho alternative
to war in the cosmos.


>and at the
>expense of most or all other manned space activity for the forseeable
>future.

The "manned" program has already chopped up solar system exploration beyond
belief, not to mention creating a bloated bureaucracy.  I for one will not
cry any tears to see it die and the Space Age begin.


>I do not consider this a good utilization of human resources in space,

I, most explorers, and all successful space commerce companies don't
consider throwing around humans in tin cans a good utilization of
human resources on Earth.

>and since I have read claims that the Planetary Society in its lobbying
>tends to imply that *all* its members support the "official" view, I have
>avoided joining the Planetary Society in spite of its many excellent
>features.

Every organization tries to show one face, a consensus opinion.
Show me how this is different than other advocacy groups.



--
Nick Szabo
[e-mail]~
"We live and we learn, or we don't live long" -- Robert A. Heinlein

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

Date: 9 Dec 90 22:43:23 GMT
From: haven!uvaarpa!murdoch!astsun.astro.Virginia.EDU![e-mail]  (Greg Hennessy)
Subject: Re: ASTRO status at 4/16:00 MET

In article <[e-mail]> [e-mail] (Robert McGwier) writes:
#Just another example of when you should NOT send a man to do a robot's job.
#From the exercises fouling up the stability to lint from uniforms clogging
#air intakes, to residue from the huge thrusters (which are only necessary
#because it is a huge plane carrying men and the HEAVY life support equipment)
#the evidence is overwhelming that good science in astronomy done from
#orbit and human presence don't mix.

Perhaps you are unaware that for the last four days the astronauts
were guiding the instruments because the "robot" was broken?

Perhaps you are unaware that this guiding CANNOT be done from the
ground because of the round trip travel time?

The entire astro concept made no sense
#after they spent umpty dumpty million dollars and then refused to fly
#it but once.  If they fly it again, its cost MIGHT come close to being
#justified.

Please, by all means, write your congresscritter about ASTRO and write
NASA about it. If NASA and congress see public interest, ASTRO WILL
fly again. I expect that the images from UIT will be available to the
press in early January, and I will try to post FITS images to the net,
although I'll have to worry about the bandwidth.

#. . . ."  We bellyache constantly in the US about the constant advances
#by the Japanese and Germans and then do not give adequate support to
#doing basic science and basic technology research.  It is pitiful.

If you think it is pitiful, write to your congresscritter. If you are
not part of the solution, you are part of the problem. (Or part of the
precipate.)


--
-Greg Hennessy, University of Virginia
 USPS Mail:     Astronomy Department, Charlottesville, VA 22903-2475 USA
 Internet:      [e-mail]
 UUCP:        ...!uunet!virginia!gsh7w

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

Date: 9 Dec 90 23:54:51 GMT
From: trident.arc.nasa.gov![e-mail]  (Peter E. Yee)
Subject: UIT Status for 12/09/90 [1500 CST] (Forwarded)


         UIT Status Report #06
         3 p.m. CST  Dec. 9, 1990
         Spacelab Mission Operations Control
         Marshall Space Flight Center

         The Goddard-developed Ultraviolet Imaging Telescope is currently
         getting long exposures on almost all its targets.  Last night the
         instrument focused on Abell 665, a rich cluster of galaxies very close
         to earth.

         "We got very deep, all night exposures," said Susan Neff, of GSFC, an
         astronomer with the UIT team.  "So we should be able to get 400 to 500
         galaxies at once with this picture.  It was probably the high point
         for the evening."

         This morning, at about 10 a.m. CST, UIT took images of the Perseus
         cluster of galaxies.  Two previous pointings were cut short due to an
         orbiter hot fire test.

         This cluster is particularly interesting because it is not symmetrical
         in shape, meaning that it may be a young cluster that could give
         scientists information about the formation of clusters.

         The images taken from UIT are recorded directly ontl a very sensitive
         astronomical film for later development at Goddard Space Flight Center
         after Columbia lands.

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

Date: 11 Dec 90 04:28:25 GMT
From: snorkelwacker.mit.edu!usc!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Magellan Update - 12/05/90


                        MAGELLAN STATUS REPORT
                          December 5, 1990

     The Magellan spacecraft is presently performing nominally and the seven
STARCALS (star calibrations) of the past 24 hours were successful with small
attitude updates.  Yesterday, mapping sequence M0339 and its associated
parameter files was uploaded and began executing at 3:48 AM PST this morning.

     The radar sensor continues to operate normally.  However, analysis of
data from orbits #958 & 959 indicates that tape recorder tracks A1 and A3 are
beginning to show the progressive deterioration that affected tracks A2 and A4.
A tape management strategy using only tape recorder B is currently being
evaluated.  The 1.8 megabits of radar data from each full mapping pass requires
four tape recorder tracks.  If only one recorder is used, small gaps occur
when the recorder switches from one track to another.

     The strategy up to this time has been to use both tape recorders, so the
second unit is recording as the first reaches the end of a track and no gaps
occur.  It may be possible to design a strategy which uses tape recorder A
only to fill the gaps.

     The SAR (Synthetic Aperture Radar) Data Processing Team produced five
standard image swaths on Monday, December 3, three from reprocessed data
records.  On December 4 they produced a test image swath from orbit #951
and twelve standard image swaths from orbits #790 thru 803.  The quality is
normal except for a small "bright patch" at about 13 degrees south latitude.
This patch is a result of a faulty SAR threshold value for one burst of SAR
data.  It is considered to be a minor problem, but it is being investigated
and appropriate corrections will be made.
      ___    _____     ___
     /_ /|  /____/ \  /_ /|
     | | | |  __ \ /| | | |      Ron Baalke         | [e-mail]
  ___| | | | |__) |/  | | |___   Jet Propulsion Lab | [e-mail]
 /___| | | |  ___/    | |/__ /|  M/S 301-355        |
 |_____|/  |_|/       |_____|/   Pasadena, CA 91109 |

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

Date: 11 Dec 90 04:42:54 GMT
From: usc!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Magellan Update - 12/10/90


                        MAGELLAN STATUS REPORT
                          December 10, 1990

     The Magellan spacecraft is presently performing nominally.  All STARCALS
(star calibrations) over the weekend were successful with small attitude
updates.  On Friday, December 7, the weekly update of radar control parameter
and mapping quaternion files was successfully sent to the spacecraft.

     Thermal and power effects of solar occultation are beginning to be seen.
The spacecraft temperatures drop while in the shadow of Venus and the battery
charge levels are slightly lower.  Starting on Saturday, December 15, we will
have periods of Earth occultation, when the playback of data to Earth is
blocked by Venus.

     Spacecraft controllers are still analyzing the performance of on-board
tape recorder A and designing a data management strategy which uses just tape
recorder B.  The single tape recorder approach would result in gaps of about
ten seconds when the tape recorder switches from one track to another.  Since
the radar is mapping about 8 kilometers of the surface in each second, the
potential gaps would be about 80 kilometers.  But because of the actual beam
width of the radar, the gaps would vary from 60 to 70 kilometers.  A technical
meeting with representatives of Odetics and Martin-Marietta is scheduled for
December 13 at JPL to discuss the tape recorder and possible corrective
actions.
      ___    _____     ___
     /_ /|  /____/ \  /_ /|
     | | | |  __ \ /| | | |      Ron Baalke         | [e-mail]
  ___| | | | |__) |/  | | |___   Jet Propulsion Lab | [e-mail]
 /___| | | |  ___/    | |/__ /|  M/S 301-355        |
 |_____|/  |_|/       |_____|/   Pasadena, CA 91109 |

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

Date: 11 Dec 90 04:10:43 GMT
From: julius.cs.uiuc.edu!usc!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Magellan Update - 12/04/90


                         MAGELLAN STATUS REPORT
                            December 4, 1990

     The Magellan spacecraft is presently performing nominally and the seven
STARCALS (star calibrations) of the past 24 hours were successful with small
attitude updates.  Magellan is now in orbit #965, so it has completed 480
radar mapping orbits.  Counting the orbits lost or degraded by this past
weekend's incident, we have lost about 18 orbits which will have to be
recovered during the extended mission.

     Later today, the weekly mapping command sequence load will be sent to
the spacecraft along with a few routine commands such as tertiary heater
settings, etc.

     While the SAR (Synthetic Aperture Radar) Processing team is awaiting the
delivery of post Superior Conjunction radar tapes, effort has been directed
toward processing "problem" data sets that have accumulated.  A software
modification was made which enabled an input data defect to be circumvented.
This made possible the processing of four new image swaths from previously
unprocessable data records. Two other image swaths were regenerated by the
High Rate Processor to correct other problems, and were successfully processed
into good quality images.
      ___    _____     ___
     /_ /|  /____/ \  /_ /|
     | | | |  __ \ /| | | |      Ron Baalke         | [e-mail]
  ___| | | | |__) |/  | | |___   Jet Propulsion Lab | [e-mail]
 /___| | | |  ___/    | |/__ /|  M/S 301-355        |
 |_____|/  |_|/       |_____|/   Pasadena, CA 91109 |

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

Date: Sun, 09 Dec 90 22:17:35 CST
From: "John Schultz" <[e-mail]>
Subject: Light years and such

Whenever I hear about a new telescope (such as the HST, etc.) I also hear
that the new telescope will be able to see even farther into the past.  Now,
I have no trouble with the idea of light speed, light years, etc., but how
can one telescope see back farther than another?  Is it due to focusing power,
or somethin ssimilar?

::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
: John Schultz                      :Disclaimer : I *pay* for this -   :
: University of Missouri - Columbia :do you think the bureaucracy      :
: Bitnet   : [e-mail]  :cares what I say???               :
: Internet : [e-mail] (128.206.1.1)                 :
::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
: Don't dream it, be it...  - Frank N. Furter, "RHPS"                  :
::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

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

Date: 9 Dec 90 23:42:47 GMT
From: usc!cs.utexas.edu!news-server.csri.toronto.edu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Who killed Nuclear Rockets? (was Re: The Next Ten Years In Space)

In article <[e-mail]> [e-mail] (Brian Yamauchi) writes:
>Given that nuclear rockets were to be such a benefit for space
>exploration, what killed them?

All the advanced missions were killed, and then the nuclear-rocket projects
were killed because there was no mission to justify them... guaranteeing
that there would be no future missions planned around them.  The near-total
shutdown of advanced-propulsion research in the early 1970s didn't help.

>What ever happened to NERVA?  What was the connection between this
>project and the projects mentioned in the quotes above?

NERVA was the most conservative nuclear rocket that anyone could think of,
and the last to die as a result.  Some of the more enthusiastic quotes may
have been aimed at the more ambitious ideas.

>If we had spent the money to develop the space shuttle on nuclear
>propulsion instead, could we have developed a practical nuclear
>orbital booster or lunar/planetary transfer vehicle? ...

The latter, almost certainly, but there would then have been the problem
of what to use to get to Earth orbit.  The former, rather more doubtful:
the orthodox nuclear-rocket systems tend to suffer from low thrust:mass
ratios, making them unsuited for lower stages, and also can have a bit
of a problem with fission products in the exhaust.  There was some talk
of a nuclear third stage for the Saturn V, which would probably have been
viable had the Saturn V survived.  Fission rockets tend to be inherently
a little "dirty", so using them for boost from the ground would have
become problematic with the cessation of above-ground nuclear testing
and the reduced tolerance for radioactive garbage in the atmosphere.
--
"The average pointer, statistically,    |Henry Spencer at U of Toronto Zoology
points somewhere in X." -Hugh Redelmeier| [e-mail]   utzoo!henry

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

End of SPACE Digest V12 #658
*******************