Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V11_4/V11_457.TXT

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Subject: SPACE Digest V11 #457

SPACE Digest                                     Volume 11 : Issue 457

Today's Topics:
              Re: Origin of SPS concept?
          Re: COMPARISON OF PROBE TECHNOLOGY
       Re: Payload Summary for 05/24/90 [Corrected] (Forwarded)
             Re: Problems of missing mass
          Re: COMPARISON OF PROBE TECHNOLOGY
            Re: Space Periodicals
           Re: Consort 3 Launch Successful
                Shuttle models
----------------------------------------------------------------------

Date: 26 May 90 16:27:40 GMT
From: hpcc01!hpsmdca![e-mail]  (Philip Walden)
Subject: Re: Origin of SPS concept?


>Peter Glaser is usually credited with it, although I do not know the
>detailed early history of the concept.

The most recent issue of Smithsonian Air & Space has a full article
on the SPS and Glaser. I have only scanned the article so far. It's
in the magazine apparently because it's the 20th anniversary of the
concept.

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

Date: 27 May 90 08:04:34 GMT
From: unmvax!nmt.edu![e-mail]  (Daniel Briggs)
Subject: Re: COMPARISON OF PROBE TECHNOLOGY

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>
>Actually, there *is* a major generation gap visible, but it's after all
>the missions you mention.  Remember that most of the hardware for Magellan,
>Ulysses, Galileo, and HST is ten years old.  The gap is between them and
>Mars Observer.

Could you possibly elaborate on the properties of the Mars Observer a bit,
Henry?  (I know that I've read about it, but I can't find the #$%*& reference
right now.)

I know that the NASA philosophy for future missions is based around two
distinct types of "modular" spacecraft.  (For the missions that aren't tough
enough to require completely custom craft, that it.)  These two types of
spacecraft are divided primarily by their mission objectives.  There is
one basic bus for the missions to terrestrial-like planets, and one for
deep space missions.  The latter class is the Mariner Mark II series, the
first two examples of which are CRAF and Cassini.  Would the Mars Observer
be perhaps the first example of the series designed for the terrestrial
planets?  In any event, do you know what the generic name is for this
series of spacecraft?

-----
This is a shared guest account, please send replies to
[e-mail] (Internet)
Dan Briggs / NRAO / P.O. Box O / Socorro, NM / 87801  (U.S. Snail)
--
-----
This is a shared guest account, please send replies to
[e-mail] (Internet)
Dan Briggs / NRAO / P.O. Box O / Socorro, NM / 87801  (U.S. Snail)

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

Date: 27 May 90 16:02:35 GMT
From: mcsun!ukc!icdoc!syma![e-mail]  (Nick Watkins)
Subject: Re: Payload Summary for 05/24/90 [Corrected] (Forwarded)

In article <[e-mail]> [e-mail] (Peter E. Yee) writes:
>          AC-69/CRRES
>          is scheduled for on or about June. 30.  All countdown events up
May 30th (launch is June 23 or so) ?

Nick
--
Dr. Nick Watkins, Space & Plasma Physics Group, School of Mathematical
& Physical Sciences, Univ. of Sussex, Brighton, E.Sussex, BN1 9QH, ENGLAND
JANET: [e-mail]   BITNET: [e-mail]

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

Date: 27 May 90 20:35:06 GMT
From: mcsun!ukc!edcastle![e-mail]  (Pavlos Papageorgiou)
Subject: Re: Problems of missing mass


    Hello!

    It was recently posted in this group that the large number of
small dark bodies postulated to exist in the inter-stellar region and
constituting a great part of the mass of galaxies, be the result of
ejections from solar systems rather than independent formation.

    While I am not qualified to make assumptions about the
feasibility of accretion of small objects (intuitively, I would imagine
there is a certain minimum mass needed to form nebulae into solid
objects), I have trouble believing that anything but a tiny fraction of
the mass of the original nebula might have been ejected in the process
of solar system formation.

    The Voyager spacecraft were recently ejected from this solar
system, but this feat caused Jupiter, Saturn, Uranus and Neptune to
suffer a loss of momentum and corresponding degradation of their orbits.
This demonstrates that ejection is indeed feasible, and not in violation
of the First Law of Thermodynamics, as the energy imparted on the
liberated body is lost from other bodies in the system.

    It is the Second Law which imposes statistical limits upon the
maximum dispersion of energies among particles in a system.  As in the
kinetic theory of gases, possesion of above average energy implies that
a particle will be interacting mostly with less energetic ones and that
these interactions would be much more likely to decrease its energy
rather than further increase it.  In addition, the total mechanical
energy of a solar system is steadily decreasing as a result of inelastic
collisions between bodies.


    I can immediately see potential difficulties with my own argument:

   ---* It is beyond this argument to imagine what happens to the mass
of the system following the death of the star. It is conceivable that
most of it might end up in cold, invisible, solid bodies.

   ---*    Additional energy is imparted upon the system from the Sun's
radiative output.  Unfortunately, this would come mostly in the form of
heat.  Presumably this would have a greater impact if the Sun ignited
very early during the formation of the system.

   ---* Much of the kinetic theory of gases, (and of Thermodynamics),
was derived from studies of particles interacting through repulsive
forces (ie.  collisions, between likely charged particles or billiard
balls).  Proving that a system of attractive (ie.  gravitational) forces
would produce similar behaviour is beyond me.

   ---* Gravity generally violates the Second Law (along with
regression, ie.  interactions between the macroscopic behaviour and
internal structure of particles).  Both of these, however, seem to
remove macroscopic mechanical energy from the system.

   ---* Evaporation is permitted by the second law.  This is because the
ejected particles, once given an improbably high energy, leave the
system and thus cease to interact with other particles, which saves them
from losing their energy back to the system.  I imagine this as the
most plausible argument in favour of the notion that a large fraction of
the system's mass may escape.

    It is a quantitative problem to determine the extent of the
evaporation effect. It is certainly possible, given enough time, for all
but a few bodies to escape, but the probability of subsequent ejections
falls dramatically as the effect progresses (in other words, evaporation
cools down the system). I am unable to make an informed estimate of
this, but my intuitive guess would be that only a small fraction of the
initial mass is likely to have made it so far.


    I would be very hapy to be corrected, or indeed to hear what is
held as accepted theory on this subject. Is there an absolute limit to
the evaportion effect, for instance?
    Thank you for reading this far!


    Pavlos Papageorgiou ([e-mail])
--------------------------------------------------------------------------------
    "The Universe always gets the last laugh" --- Richard P. Feynman

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

Date: 25 May 90 13:39:11 GMT
From: att!cbnewsl![e-mail]  (Stuart Warmink)
Subject: Re: COMPARISON OF PROBE TECHNOLOGY

[e-mail] (Henry Spencer) writes:

> Actually, there *is* a major generation gap visible, but it's after all
> the missions you mention.  Remember that most of the hardware for Magellan,
> Ulysses, Galileo, and HST is ten years old.  The gap is between them and
> Mars Observer.

Even Mars Observer isn't as new as it may seem - the design (other than the
payload and communications) is based heavily on existing geostationary
comsat components in order to keep the cost down. Mars Observer will enter
a circular sun-synchronous (2PM) orbit around Mars, though.
--
------------------------------------------------------------------------------
Stuart Warmink, Whippany, NJ, USA  |  [e-mail]  |       Hi!
-------------------------> My opinions are just that <------------------------

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

Date: 27 May 90 05:09:22 GMT
From: sdd.hp.com!elroy.jpl.nasa.gov!zardoz.cpd.com!dhw68k!ofa123![e-mail]  (Wales Larrison)
Subject: Re: Space Periodicals

Bill, you were looking for a discussion on the quality of space-
oriented magazines -  here are few more you've missed...

  Space Business News - bi-weekly, very good, but about $260/year
  Interavia - European, but covers European and U.S. aerospace
  Space - British publication, slick and good looking, about $60/yr
  Military Space - bi-weekly, very good, but about $260/year
  Aerospace Daily - Very good, rather expensive ($400?) daily
  Defense Daily - Very good, also rather expensive daily
  Space Daily - Very good, but expensive
  Space Markets - Bi-monthly, European, so-so
  Satellite Week - Very good, very specialized for comsats
  Flight International - Very good "the Aviation Week of Europe"
  Space Policy - Quarterly, but good articles
  Interspace - European, primarily Satellite communications, bi-weekly

  I would rate the best space publications (for other than very
general intersest publications) as Space News, Aviation Week, (pretty
much a tie...) Space Business News (in some ways better...), and
Aerospace Daily (if you positively, absolutely have to know...).  I
try to skim these publications every week.  But - they require some
area knowledge.   AvWeek is probably the best for overall technical
depth, but Space News is a good weekly read and is more focused on
space.  Space Business News is very good, and oriented more towards a
general business community reader (I enjoy it the most...).
   If I was getting a non-spacer involved in space, it would have to
be "Final Frontier" as the first choice.  Then Planetary Report" or
"Ad Astra" or "Spaceflight", since these magazines are "choir"
magazines.
---------------------------------------------------------------------
Wales Larrison                  "Space Technology Investor"



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

Date: 27 May 90 12:28:56 GMT
From: xavax![e-mail]  (Phillip Harbison)
Subject: Re: Consort 3 Launch Successful

In article <[e-mail]> [e-mail] (Edward V. Wright)
writes:
> [e-mail] (Phillip Harbison) writes:
>
> > The following is a summary of information carried in newspaper
> > articles by The Huntsville Times, The Huntsville News, and the AP wire.
>
> > Deke Slayton, a former Mercury astronaut, is the president and founder
> >  of SSI.
>
> Not true!  Deke Slayton did not join SSI until after the Percheron
> rocket, built for SSI by GCH Inc., exploded during a static engine
> test and SSI decided to switch to solid-fueled rockets.

My apologies for the inaccuracy.  I rechecked my sources and there was
no claim, either by the AP wire or the Huntsville papers, that Slayton
was a founder of SSI.  I don't know where I got the wrong information
(perhaps from the vacuum inside my head? :-).

--
Live: Phil Harbison, Xavax, P.O. Box 7413, Huntsville, AL 35807
Uucp: [e-mail]
Bell: 205-539-1672, 205-880-8951

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

Date: 28 May 90 01:37:55 GMT
From: [e-mail]  (Kevin Dowling)
Subject: Shuttle models



Does anyone know what high-quality scale models of spacecraft (specifically
the shuttle) are available or which companies make them?

I found that Monogram and Revell make a 1:72 scale model of
the orbiter and the Revell seems
to be slightly better detailed than the Monogram. They also make
1:148 and 1:200 scale models of the orbiters.

At Kennedy Space Center's Spaceport they have a selection of a few models
like those mentioned above and an Ertl die-cast model too.

nivek

aka :    Kevin Dowling
net :    [e-mail]    Robotics Institute
tel :    [phone]        Carnegie Mellon University
                Pittsburgh, PA 15213

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

End of SPACE Digest V11 #457
*******************