Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V11_3/V11_327.TXT

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Subject: SPACE Digest V11 #327

SPACE Digest                                     Volume 11 : Issue 327

Today's Topics:
              Galileo Update - 04/27/90
                  Re: [HELP]
         Re: YAPLI (Yet Another Pegasus Launch Idea)
            Re: The Drake Equation
                  Re: [HELP]
     Re: PegBlimp (was Re: Pegasus launch from Valkyrie  (or ...)
              Re: Fermi Paradox
           Re: Pegasus launch is a success!
              The Drake Equation
----------------------------------------------------------------------

Date: 27 Apr 90 23:50:08 GMT
From: usc!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Galileo Update - 04/27/90



                              GALILEO
                       MISSION STATUS REPORT
                          April 27, 1990

     As of noon Friday (PDT), April 27, 1990, the Galileo spacecraft is
91,960,640 miles from the Earth, 18,762,160 miles from Venus and traveling at
a heliocentric velocity of 71,230 miles per hour.  Galileo is spinning at 3.15
rpm in a cruise mode-dual spin.  The spacecraft attitude sun point angle is at
2.2 degrees.  All thermal control temperature are within acceptable range.
Round trip light time is 16 minutes, 24 seconds.

     The Venus-Earth (VE-3) sequence, which was successfully loaded onboard
the spacecraft on April 20, went active as planned on April 23.

     Two SITURNS to lead the sun were successfully performed on April 23 and
April 26.  The spacecraft performance for these activities was as expected and
without incident.

     Cruise Science Memory Readouts (MROs) were successfully completed for
the Magnetometer (MAG), Dust Detector (DDS), and Extreme Ultraviolet (EUV)
instruments on April 24 and 27.

     The eleventh RPM thruster "flushing" activity was successfully performed
on April 27.  The activity flushed the Z, L and S thrusters only.  The P
thrusters were not flushed since they are used periodically to perform the
SITURNS.  These activities were performed at 40 bps and consequently thruster
temperature profiles were not available due to low telemetry sample rate.
Successful flushing was inferred from other spacecraft measurements/events,
including attitude control performance and thruster counts.

     The AC bus imbalance measurement remained nearly constant exhibiting very
little change from about 47.5 to 48 volts.  The DC bus imbalance measurement,
however, fluctuated about 1.6 volts from 21.6 volts to about 20 volts with some
fluctuations occurring during periods of relatively quiescent spacecraft
operation; but some significant DC imbalance measurement changes (3 to 4 volts)
were observed during some DC load switching events associated with the planned
SITURN on April 23.  However, during numerous earlier SITURNS no or very little
(1-2 DN) imbalance measurement change was observed.  During the SITURN
activity on April 26, the DC bus imbalance measurement changed approximately 1
DN  (.1 volt).

     During the uplink of the VE-3, the second command file was transmitted
about two minutes earlier than requested by the Mission Control Team.  This
occurred after a ground uplink command abort and after the uplink had
been restarted; the reason for the ground command abort is currently under
investigation.  The VE-3 sequence was properly loaded. The early transmission
problem was later reproduced during ground tests and is associated with the
particular procedure used to send the command files to the Command Processor
Assembly (CPA) at the tracking station.  A revised procedure to prevent the
early transmission problem from reoccurring has been implemented while the Deep
Space Network (DSN) investigates the problem further with the support of the
Galileo Flight Control and Support Office.

     Investigation of the sinusoidal signature in the doppler residuals of the
70 meter antenna in Spain (DSS-63), which appeared shortly after launch prior
to DSS-63 antenna bearing downtime, has been resumed now that DSS-63 doppler
data from the Low Gain Antenna (LGA-1) is available again.  Preliminary
indications are that the previously observed variations are no longer present
at DSS-63 and are not seen in the 70 meter antennas in Goldstone (DSS-14) or
Australia (DSS-43).  Assessment of the final data will be made before the
matter is closed.

 Ron Baalke                       |    [e-mail]
 Jet Propulsion Lab  M/S 301-355  |    [e-mail]
 4800 Oak Grove Dr.               |
 Pasadena, CA 91109               |    Go Lakers!

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

Date: 28 Apr 90 02:22:35 GMT
From: well![e-mail]  (Avery Ray Colter)
Subject: Re: [HELP]


I've always been ticked that the DoD so blindly (except for research colleges)
takes and takes and takes from education, and then turns around and wonders why
there is a shortage of engineers and a predicted shortage of engineering
faculty!

Now, I'm not the highest GPA in my class (partly due to my reading netnews
<grin>), but it is clear to me that the current path of the Iron Triangle is
not doing very well.

The head of DARPA got demoted for trying to promote some civilian
concentrations in technology projects. The next head is liable to be
the classic militarist who will again train our best minds in skills
which are of use only in milspec environments and don't count for shit
in the capitalist battlefield that is the rest of the economy - you know,
the part of the economy which actually PRODUCES something.

Federal funding cuts do affect the states' abilities to fund school systems.
If the general federal outlays to states are reduced, the states are forced
to operate on a tighter belt. Which means education and many other local-level
programs suffer.

--
Avery Ray Colter    Internet: [e-mail] | {apple|hplabs}!well!avery
     o/~ Mama, mama, mama, keep those skinny girls at home,
         o/~ `Cause this skinny boy wants a BIG FAT BLONDE!   - The Rainmakers

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

Date: 27 Apr 90 14:54:06 GMT
From: ccncsu!ncr-fc![e-mail]  (Mike McManus)
Subject: Re: YAPLI (Yet Another Pegasus Launch Idea)

In article <[e-mail]> [e-mail] (Vincent Cate) writes:
>
>   Kevlar cables should be ok for the above design.  I not sure about
>   the pulleys (kevlar pulleys ok?).  I have been trying to get some info
>   on kevlar stuff.0

I'm not an ME, nor am I a sailor, so my only real experience with pulleys was
in physics lab, but...

When I think of pulleys and block-and-tackle systems, I usually picture things
moving rather slowly.  Is it possible to have a pulley system running at
thousands of miles an hour, or is that just asking for trouble?  If the line
got even slightly out of allignment with the pulleys, you would have a big
mess, I would think.  How could the alignment issue be addressed at such high
speeds?

--
Disclaimer: All spelling and/or grammer in this document are guaranteed to be
            correct; any exseptions is the is wurk uv intter-net deemuns,.

Mike McManus ([e-mail]) <- This should work soon!
NCR Microelectronics
2001 Danfield Ct.                   ncr-fc![e-mail], or
Ft. Collins,  Colorado              ncr-fc![e-mail], or
[phone]   Ext. 307           uunet!ncrlnk!ncr-sd!ncr-fc!garage!mikemc

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

Date: 27 Apr 90 19:03:10 GMT
From: sdd.hp.com!elroy.jpl.nasa.gov!jpl-devvax![e-mail]  (Larry Wall)
Subject: Re: The Drake Equation

In article <[e-mail]> [e-mail] writes:
:         Needless to say, this formula is comprised mostly of currently
:     unknown factors; depending on various estimates, there may be as many
:     as one million or as few as ten advanced civilizations in our galaxy.
                                  ^^^

By some estimates there may be as few as one.  We have too small a statistical
sample of planets on which life developed to say Anything Whatsoever about
the probability of life developing.  Perhaps the probability is 1 in 10^28
and we just got lucky.

By other estimates there may be as few as zero advanced civilizations in
our galaxy...  :-)

I suppose a case could even be made that there are -1 advanced civilizations
in our galaxy...     :-)  :-)  :-)

Larry Wall
[e-mail]

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

Date: 26 Apr 90 18:50:23 GMT
From: skipper![e-mail]  (Al Bowers)
Subject: Re: [HELP]

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

>That's what happens when public school systems hire people with
>'education' degrees and refuse to set minimal standards.

>I would like to see the public schools require courses in biology,
>chemistry, physics and mathematics (statistics and algebra).
>Why do they let students get away with 'business math' and
>'general science'?  There is no reason that most students couldn't
>take and pass these courses.  I would also require a secondary
>school teacher to have majored in the field they are teaching.

Both my in-laws are teachers.  The fact that either of them are
capable of tying their own shoelaces in the mornings amazes me
sometimes (oh, that's right, they use Velcro! ;-).  I have often
thought about teaching high school math or physics or junior college
level astronomy or...  But I am told that even if I pass the
California CBEST (teachers test) due to my lack of a degree in
education (B.S. in Aero Engr and M of Engr in Aerothermo) and lack of
experience (only 10 years as a working engineer here at NASA, 2 years
as lead aerodynamics engineer on the F-18 high angle of attack vehicle
project) that I would not be eligible for very many promotions.  And
these are the same educators that wonder why the U.S. can't compete
against little countries like Japan.

>--
>John Limpert        [e-mail]    uunet!n3dmc!gronk!johnl

--
Albion H. Bowers  [e-mail] ames!elxsi.dfrf.nasa.gov!bowers

`In the changing of the times, they were like autumn lightning, a
thing out of season, an empty promise of rain that would fall unheeded
on fields already bare.'
                              attributed to Abe Shosaburo by Dave Lowery

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

Date: 26 Apr 90 18:37:44 GMT
From: phoenix!astro![e-mail]  (Michael Woodhams)
Subject: Re: PegBlimp (was Re: Pegasus launch from Valkyrie  (or ...)

In article <[e-mail]> [e-mail] (Russ Cage) writes:
>In article <[e-mail]> [e-mail] (Tom Neff) writes:
>>What about launching Pegasus from a dirigible?
[stuff removed]
>Yes, it matters a great deal.  Mass-ratio requirements increase
[stuff removed]
>0   kg  if launched with a 1134 m/sec penalty;
>125 kg  if launched with a 500  m/sec penalty;
>247 kg  if launched with a 0    m/sec advantage (blimp into polar orbit);
>317 kg  if launched with a 250  m/sec advantage (airplane into polar orbit);
>385 kg  if launched with a 470  m/sec advantage (eastward launch from equator);
>469 kg  if launched with a 720  m/sec advantage (eastward airplane launch).
>
>Note that a 9% advantage in launch speed gives a *90%* increase
>in payload.  This translates to a big cut in $/kg to orbit.
I can't see any 9% advantages in launch speed, and certainly not any
90% increases in payload for small change in velocity. Almost doubling
velocity increases the payload by 21% (from 250 m/s, 470 m/s figures.)

>LTA craft have other problems:  their lifting gas expands with
>altitude, which gives them a service ceiling usually < 15,000 ft.
>An airplane can climb above much more of the atmosphere, which
>reduces drag penalties as well.  In short, an airplane is a much
>better launcher candidate than a blimp or dirigible.

What ever gave you this idea? Balloons go higher than anything but
rockets. If your balloon holds a fixed mass of gas, you simply enclose
it in a much larger volume than the gas fills at ground level. More
realistically, as you gain altitude you can let gas out of your
balloon.

Launching Pegasus at twice the velocity of the B52 is very hard and
expensive, but launching from three times the height and zero velocity
from a balloon should be simple. How does payload vary with launch
altitude?

Michael Woodhams.

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

Date: 26 Apr 90 08:37:25 GMT
From: jtsv16!geac!sq![e-mail]  (Mark Brader)
Subject: Re: Fermi Paradox

>  Humans are very Chauvinist when it comes to carbon and water
 ] There are only 2 elements that are capable of being the basis of
 ] creating long, complex molecules, and those are carbon and silicon...
}  Actually, silicon makes a lousy carbon substitute.  It's just different
}  enough chemically that it prefers to clump up in rings and the like ...

Isaac Asimov (whose Ph.D. is in biochemistry, remember) addressed this
question in a speculative 1961 essay called "Not As We Know It",
reprinted in 1974 in the collection "Asimov on Chemistry".

He proposed 5 hypothetical alternative chemistries for life, each suited to
a different range of temperatures.  Along with our own, the list
from hottest to coldest is:

    Long-Chain Chemicals        Reaction Medium

1.    fluorosilicones            simpler fluorosilicones
2.    fluorosilicones            sulfur
3.    nucleic acids and proteins    water
4.    nucleic acids and proteins    ammonia
5.    lipids                methane
6.    lipids                hydrogen

The 6 cases fall into 3 pairs and the long-chain molecules would not
necessarily be the same in each case; in particular, the proteins in
number 4 would have more nitrogen and less oxygen than ours.

--
Mark Brader            "It can be amusing, even if painful, to watch the
SoftQuad Inc., Toronto         ethnocentrism of those who are convinced their
utzoo!sq!msb, [e-mail]     local standards are universal."    -- Tom Chapin

This article is in the public domain.

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

Date: 26 Apr 90 23:41:21 GMT
From: [e-mail]  (Ken Hoover)
Subject: Re: Pegasus launch is a success!

In article <[e-mail]> [e-mail] writes:
>[...]  a winch sitting on the
>ground that accelerates a Pegasus sitting on the ground (well, on a
>dolly) to a high speed.  Seems to me that a decent winch could get
>our Peg up to several hundred miles per hour.
>

  There's an amusement park just outside Pittsburgh, PA (Kennywood to all
the natives) that has a loop-the-loop roller-coaster ride that
consists of a long straight and level track with a single loop in it
and two to reverse the direction of the train.  The whole thing is
powered by an 8' or so flywheel made from several layers of 2" steel
plates that is kept spinning at high speed (3000+rpm?).

  To start the ride, the operator activates a clutch which makes the
flywheel pull the train down the track toward the loop by the use of a
sled that is reeled in by the flywheel, accelerating the train (10-12
cars) into and around the loop.  An electric motor then kicks in to
accelerate the flywheel back to its normal speed, and the whole thing
is ready for the next trip. I suppose a similar thing might be useful
for a small object to be projected at high speeds...

>David Wolff
>[e-mail]  or  [e-mail]
>Disclaimer:  the above posting is not intended to represent Prime
>policy.

                    - Ken

------------------------------------------------------------------------------
Ken Hoover [ [e-mail] | [e-mail] ]
     Senior undergraduate consultant, SUNY-Binghamton Computer Center
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
          " Never trust a computer you can't lift. "  - Stan Masor
------------------------------------------------------------------------------

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

Date: 27 Apr 90 16:52:43 GMT
From: shlump.nac.dec.com!renoir.dec.com![e-mail]
Subject: The Drake Equation


        The following formula, affectionately known as the Drake Equation,
    as it was created by Frank Drake (and Carl Sagan) in the 1960s, is set
    up thusly:

                              N = R*fgfpneflfifaL

          N - The number of advanced technological civilizations in the
              Milky Way Galaxy.

         R* - The mean birth rate of stars in the Milky Way Galaxy.

         fg - The fraction of stars resembling the Sun which are not
              members of binary or multiple star systems.

         fp - The fraction of such stars with planetary systems.

         ne - The number of Earth-like planets in each system orbiting
              within the life-supporting zones of their stars.

         fl - The fraction of these planets where life has arisen.

         fi - The fraction of life-bearing planets on which life has
              developed intelligence.

         fa - The fraction of intelligent civilizations which have
              developed an advanced technology.

          L - The average lifetime of civilizations with advanced
              technology.

        Needless to say, this formula is comprised mostly of currently
    unknown factors; depending on various estimates, there may be as many
    as one million or as few as ten advanced civilizations in our galaxy.
    This equation also does not take into account intelligent races which
    may have developed in environments other than Earth-like worlds and do
    not possess and/or use technologies recognizable to humans.

        Larry Klaes  [e-mail]
             or - ...!decwrl!wrksys.enet.dec.com!klaes
                 or - [e-mail]
                     or - [e-mail]

             "The Universe, or nothing!" - H. G. Wells

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

End of SPACE Digest V11 #327
*******************