Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V12_6/V12_645.TXT

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Date: Thu, 13 Dec 1990 01:40:45 -0500 (EST)
Subject: SPACE Digest V12 #645

SPACE Digest                                     Volume 12 : Issue 645

Today's Topics:
           Re: atmospheric pressure on Mars
    Re: Good Bye  (Quite possibly my last posting from this site)
       BBXRT Status for 12/06/90 [1430 CST] (Forwarded)
               Dr. Scott Madry lecture
              Re: Photon engine
             Re: MAJOR SOLAR FLARE ALERT
             Re: * SpaceNews 03-Dec-90 *
      Astro-1 Status for 12/05/90 [2130 CST] (Forwarded)
           Re: Payload Specialist Selection
              Re: Another Russian first

Administrivia:

    Submissions to the SPACE Digest/sci.space should be mailed to
  [e-mail].  Other mail, esp. [un]subscription notices,
  should be sent to [e-mail], or, if urgent, to
             [e-mail]

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

Date: 6 Dec 90 08:04:25 GMT
From: eru!hagbard!sunic!mcsun!unido!fauern!forwiss.uni-passau.de!nntpserver![e-mail]  (Michael Himsolt)
Subject: Re: atmospheric pressure on Mars


The  avarage athmospheric pressure on  Mars  is 4.9 mbar, the  maximal
pressure is thought to be ~10 mbar (in very deep regions like Hellas).
The maximum pressure recorded by Viking (2) was ~8 mbar.

There has been a discussion on the net about exposing  human bodies to
the vacuum -  in '2001'  there is such  a scene (I did not  see 'Total
Recall'). If my memory serves me right, the body does *not* blow up or
explodes, simply because the forces are much too weak.

In  the 50's and  early  60's,  some people believed   the atmospheric
pressure on Mars to be ~100 mbar. I am not shure whether a human could
live in such an environment even with a respirator.

-- Michael
--
Michael Himsolt,  Universitaet Passau,  Postfach 2540,  D-8390 Passau,  GERMANY
[e-mail]                             [e-mail]

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

Date: 6 Dec 90 20:43:18 GMT
From: spotted.rice.edu![e-mail]  (Shawn Joel Dube)
Subject: Re: Good Bye  (Quite possibly my last posting from this site)

In article <[e-mail]>, [e-mail] (Shawn Joel Dube) writes:
|> In article <[e-mail]>, [e-mail] (Robert Casey) writes:
|> |> I'm afraid that this may be my last posting.  Philips is having layoffs, and I
|> |> might get canned.....
|>
|>
|> This brings up a question.  How many people subscribe to this
|> newsgroup???  I'm curious to know.
|>
|> Just EMail a small letter and I'll post a total count in about a week.
|>


Sorry I ask!!!!  It's well over 70 so......Please, no more mail :-)

--
rrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr
r     ___     _              "...but then there was the         r
r    /__     | \              possibility that they were        r
r   ___/hawn |__\ube          LaRouche democrats which, of      r
r  [e-mail]        course, were better off dead."    r
rrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr

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

Date: 6 Dec 90 23:29:40 GMT
From: trident.arc.nasa.gov![e-mail]  (Peter E. Yee)
Subject: BBXRT Status for 12/06/90 [1430 CST] (Forwarded)


         BBXRT Status Report #05
         2:30 p.m. CST Dec. 6, 1990
         Spacelab Mission Operations Control
         Marshall Space Flight Center,
         Huntsville, AL


         Controlling BBXRT and its Two Axis Pointing System (TAPS) from the
         ground at Goddard Space Flight Center in Greenbelt, MD, has allowed
         BBXRT team members the opportunity to do science observations despite
         today's shut down on the Dedicated Display Unit (DDU).

         During the next 12 hours while flight controllers, mission management
         and science teams work to troubleshoot the DDU problem, BBXRT team
         members at Marshall Space Flight Center and at GSFC will use this
         period to further test the alignment of the instrument and to look at
         several high priority targets, said Dr. Peter Serlemitsos of GSFC,
         principal investigator.

         Observations today include NGC 4051, a Seyfert galaxy, and Q 1821, a
         quasar.  This afternoon, BBXRT also plans to observe Supernova 1987A.
         BBXRT was not part of the originally selected Astro payload.  It was
         added to the mission after the appearance of Supernova 1987A in
         February 1987.

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

Date: 7 Dec 90 00:37:09 GMT
From: window![e-mail]  (Marc Wayne Mcconley)
Subject: Dr. Scott Madry lecture

Dr. SCOTT MADRY to speak at Princeton University

Princeton, NJ - Dr. SCOTT MADRY, Associate Director of Cook College
Remote Sensing Center at Rutgers University, will give a public lecture
at Princeton University on the evening on Tuesday, December 11.  He will
discuss NASA's Mission to Planet Earth and the International Space
University (ISU).

Madry will serve as Chair of the Satellite Applications Department at
the International Space University to be held in Moscow this summer.
ISU offers graduate-level programs encompassing space-related fields
from architecture and engineering to life sciences and business.  In
1989 he was a Senior Project Manager at the Institute for Technology
Development, Space Remote Sensing Center, at NASA Stennis Space Center.
Madry has also conducted field research in the U.S. and Europe related
to the applications of satellite remote sensing data for environmental
and ecological analysis.

His talk is sponsored by the Princeton Planetary Society, Princeton's
space-interest organization and a chapter of the National Space Society.
The event will begin at 7:30 pm in the Auditorium of McCormick Hall (the
Art and Archaeology Building) on the Princeton University campus.
Admission is free; parking is available.  For more information, contact
PPS President Audrey Robinson at [phone].

--
Marc W. McConley
Vice President, Princeton Planetary Society
Reply-To:  [e-mail]  ||  [phone]

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

Date: Wed, 5 Dec 90 20:32:56 EST
From: John Roberts <[e-mail]>
Disclaimer: Opinions expressed are those of the sender
    and do not reflect NIST policy or agreement.
Subject: Re: Photon engine


>From roberts Fri Nov 30 21:01:57 1990
>Subject: Re: Photon engine

>Some other interesting general formulae to compare photon drives and matter
>reaction mass drives:

>Drive           momentum xfer / energy
>-----           ----------------------
>photon          1 / c
>matter          2 / v

>which illustrates that a matter drive will always give more than twice as
>much thrust per joule than a photon drive (since v < c). Also, a matter drive
>uses energy more efficiently when exhaust velocity is lower, which means that
>it is always in your best interest to use as much reaction mass as you have
>available. Pushing against a large celestial body (i.e. linear launcher) is
>particularly efficient. Note that the force of a photon drive depends only
>on the power radiated - wavelength is irrelevant.

Oops! As Steve Willner pointed out, this is a non-relativistic calculation
for matter. Poking around with the numbers a little, I get:

  kinetic energy = rest mass * c^2 * ((1 - L) / L),
  momentum       = rest mass * v / L
    where L = sqrt(1 - v^2 / c^2)

  Drive          momentum xfer (impulse) / energy
  -----          --------------------------------
  photon         1 / c

  matter         v / (c^2 * (1 - sqrt(1 - v^2 / c^2)))

which is about (2 / v) for (v << c), but which approaches (1 / c) as
v approaches c. Thus, if exhaust velocity is very close to the speed of light,
it doesn't matter whether you think of the exhaust as matter or energy, since
the result is much the same. In either case, energy efficiency is much less
than for the use of slower matter as reaction mass. For instance, a hydrogen-
oxygen rocket engine with a specific impulse of 450 has (impulse / energy)
or (thrust / power) of about 4.54E-4, meaning that it is nearly 140000
times as energy-efficient as a photon drive, which is why it is able to
launch against earth's gravity with so little power and such a small total
energy consumption compared to what a pure photon drive would require.
Note: for the formula given above, you need plenty of digits of accuracy -
I used 30.

Also, for the photon purists, I believe that with the right material for
a reflector, a "spotlight" would almost always be better than a laser.
The coherence and monochromatic output of a laser don't get you anything,
except perhaps in terms of the physical characteristics of the reflector.
       John Roberts
       [e-mail]

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

Date: 6 Dec 90 23:03:58 GMT
From: uhccux!munnari.oz.au!metro!cluster!ultima![e-mail]  (Dan Corbett)
Subject: Re: MAJOR SOLAR FLARE ALERT

[e-mail] (Cary Oler) writes:

>     Flare probabilities for the next 72 hours (ending 07 December) follow:

>             Flare        Probability
>             Type       24hr  48hr  72hr
>       --------------   ----  ----  ----
>       Class M Flare     60%   60%   60%
>       Class X Flare     20%   20%   20%
>       Proton Flare      05%   05%   10%

Sorry if this has been discussed before, but could you give a brief explanation
of what each of these types of flares are?

------------------------------------------------------------------------------
Dan Corbett
University of Technology, Sydney
Sydney, New South Wales, Australia
------------------------------------------------------------------------------

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

Date: 6 Dec 90 17:36:28 GMT
From: sdd.hp.com!wuarchive!cs.utexas.edu!news-server.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: * SpaceNews 03-Dec-90 *

In article <[e-mail]> [e-mail] (Franklin Antonio) writes:
>... How can this billions of years stability stuff be science
>if you can't test the result of the theory?  Meet me in two billion years
>for pizza.  If it turned out that the solar system WAS stable, i'll buy you
>a beer.

Seen in Usenet newsgroup sci.space.celmech.history, 6 Dec 2000001990:

    The adjudicating committee appointed last year has regretfully
    announced that the Two Billion Year Bet has had to be called off.
    The pizza was good, but everyone had to buy their own beers.
    (The management did, however, agree to a special rate, only
    $6945/liter for an excellent import from Heidelberg IV.  The
    local branches of the major US brewers offered to provide beer
    free, but everyone naturally ignored them.)  Citing impossible
    difficulties in deciding whether the solar system would have
    been stable if left alone, the committee concluded that no
    settlement of the bet was possible.  "Moving Venus and Mercury
    out was not that big a deal, and we think we could have allowed
    for that, but the Arts Council grant of 3476876 for rearranging
    the asteroids into aesthetically pleasing formations by modulating
    the orbit of Jupiter just caused hopeless confusion, and when the
    Flat Ecliptic Society started tidying the orbits up in preparation
    for the Galactic Fair of 78654379, well, that was the last straw.
    Not even the generous donation of five milliseconds of Cray-94673
    time by UUNET Intergalactic Communications Inc was sufficient to
    decide what would have happened if the upkeep of the solar system
    had been neglected for so long."
--
"The average pointer, statistically,    |Henry Spencer at U of Toronto Zoology
points somewhere in X." -Hugh Redelmeier| [e-mail]   utzoo!henry

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

Date: 6 Dec 90 22:59:53 GMT
From: trident.arc.nasa.gov![e-mail]  (Peter E. Yee)
Subject: Astro-1 Status for 12/05/90 [2130 CST] (Forwarded)


      Astro 1 Shift Summary Report #12
      9:30 p.m. CST, December 5, 1990
      3/20:40 MET
      Spacelab Mission Operations Control
      Marshall Space Flight Center


      The Astro-1 astronomy mission's pace of observation continued to
      show improvement Wednesday as crewmembers aboard Columbia, along
      with the ground support team, made further progress with
      operations.  During the period from noon to 8 p.m. (CST), a variety
      of targets were acquired and observed by the three specialized
      ultraviolet telescopes.  The range of data-taking periods continued
      to vary substantially, from just a few minutes in some cases to some
      of the longest so far in the mission.

      One significant procedural improvement evolved during this period,
      in an effort to most efficiently aim and stabilize the ultraviolet
      telescopes on each planned target.  The plan involves making a
      decision prior to beginning each observation period whether the crew
      should use the automatic or manual mode of locking on desired
      targets with the Instrument Pointing System (IPS) and star
      trackers.  The determination as to the most promising acquisition
      mode is being made by a team in the Spacelab Mission Operations
      Control Facility and then voiced up to the crew aboard Columbia.

      "We still want to get to routine use of the automatic mode of IPS
      acquisition, since the pointing accuracy will be higher," said
      Astro-1 Mission Scientist Ted Gull.  But, he said, the case-by-case
      determination regarding acquisition modes appears to be the best
      approach at this point in the mission.

      Some of the observations during this period stood out as particular
      highlights for science teams on the ground.  For instance, following
      an observation of the quasi-stellar object 3C273, Principal
      Investigator Dr. Arthur Davidsen of the Hopkins Ultraviolet
      Telescope was elated.  A congratulatory message from Davidsen was
      passed up to the Astro-1 crew, noting "the great 3C273 spectrum."
      And a period of data acquisition on the hot supergiant star P Cygni
      brought enthusiastic comments from members of the Wisconsin
      Ultraviolet Photo-Polarimeter Experiment science team.  Crew
      Interface Coordinator Debra Underwood relayed to Columbia the
      message that "the WUPPE team really appreciates your effort on this
      target.  They say they got a very good signal-to-noise ratio in the
      data."

      Ground controllers for the Broad-Band X-ray Telescope continued to
      work on fine-tuning the alignment of their instrument with its
      pointing system.  Prior to this period, they had been acquiring good
      data, but experienced alignment difficulties which caused them to
      miss several data opportunities.  They reported making progress
      during the afternoon and evening but were not yet successful in able
      to consistently get X-ray photons into their telescope's central
      detector element.  Nevertheless, they acquired useful spectral data
      today during pointings at the X-ray source LMC X-1 in the Large
      Magellanic Cloud and at two galactic binaries -- 3U 0614+09 and EXO
      0748-676.

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

Date: 6 Dec 90 14:27:41 GMT
From: pilchuck!seahcx!phred![e-mail]  (Pete Jarvis)
Subject: Re: Payload Specialist Selection

In article <[e-mail]> [e-mail] (Brian Yamauchi) writes:
>
>How are payload specialists selected for shuttle flights?
>Do payload specialists need to meet the same criteria as mission
>specialists?  In particular, do they need to meet the vision
>requirement?
>Is their training the same as for mission specialists, or is it
>limited to the skills they will need for their particular mission?

*Payload Specialists do not have to meet the same requirements as do MS's.
*An MS is a career Astronaut. A PS is not. PS training is mission dependent
*with the addition of about 6 months training in Houston on Shuttle Systems.
  --- Peter Jarvis --- Physio-Control, Redmond, WA.

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

Date: 6 Dec 90 04:49:55 GMT
From: agate!bionet!uwm.edu!zaphod.mps.ohio-state.edu!sdd.hp.com!news.cs.indiana.edu!msi.umn.edu!cs.umn.edu!kksys!wd0gol!newave![e-mail]  (John A. Weeks III)
Subject: Re: Another Russian first

In article <[e-mail]> [e-mail] writes:
> We had the first space station (Skylab)

BZZZT! Wrong.  Skylab launched 14 May 1973, Salyut 1 launched 19 April 1971.

Interesting to note that the Soviets have had a string of workable space
stations, while Skylab 2 is sitting inside of the National Air & Space Museum.

-john-

--
===============================================================================
John A. Weeks III               [phone]               [e-mail]
NeWave Communications                 ...uunet!rosevax!tcnet!wd0gol!newave!john
===============================================================================

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

End of SPACE Digest V12 #645
*******************