Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT_ZIP/spacedig/V10_1/V10_135.ZIP/V10_135

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Date: Wed, 11 Oct 89 04:22:47 -0400 (EDT)
Subject: SPACE Digest V10 #135

SPACE Digest                                     Volume 10 : Issue 135

Today's Topics:
      Galileo Mission Design (was Re: Magellan summary?)
               Hauling asteroids about
             Re: The Moon vs. My Backyard
             Re: The Moon vs. My Backyard
             Re: The Moon vs. My Backyard
          Galileo--- history repeats itself
  UPI space & shuttle coverage available free in biz.clarinet.sample
             Re: Hauling asteroids about
   Re: The Sad Tale of Galileo, Centaur, and the Invincible 'Nauts
    Re:  Happy Birthday, Robert Goddard and Konstantin Tsilkovsky.
----------------------------------------------------------------------

Date: Mon 9 Oct 89 11:25:39-PDT
From: Brian Keller <[e-mail]>
Subject: Galileo Mission Design (was Re: Magellan summary?)

swrinde!cs.utexas.edu!ut-emx![e-mail]  (Feulner ... Matt Feulner)
writes:

>In article <[e-mail]>
>[e-mail] (Peter Scott) writes:
>
>>Some trajectory wizard (who plainly
>>deserves a medal, IMHO) discovered this bizarre track that enabled Galileo to
>>reach Jupiter with the IUS booster.  It's the most creative piece of mission
>>planning I've seen since I started working here (<- this is called a hook).
>
>No doubt a grad student slave who never gets any credit.  I'm
>pretty sure it was a grad student who first realized the Grand
>Tour/Voyager trajectory.

Take a look at the Sept. version of Aerospace America - should be available
in any sort of engineering library.  There's an article on the chaos
surrounding the mission design for Galileo as its launch vehicles have
been changed annually.  They also mention Roger Diehl as having basically
designed the current mission.  As I have worked at JPL off and on over the
years with Roger as my supervisor, I agree that the article is pretty much
true.  After Challenger, things were quite a mess.  The article describes
what happened quite accurately, although a number of people were working on
the problem at the time.  Roger was the one who did make the breakthrough.

Dr. Roger Diehl is hardly a grad student, though - he's an experienced
mission designer who began looking at Galileo type missions in the mid-70's
when the preliminary work was started without the benefit of the host
of mission design software we now have at JPL.  Back then they would make
educated guesses for trajectories, integrate them out to see the result,
and try again.  It could easily take months to find just one mission that
would work at all.  Now the process from design, OPTIMIZATION, and
integration for a candidate tour can be done in a matter of days if need be.
Basic mission design is still an art, however - there is nearly an infinite
number of possible missions, but it takes an experienced mission designer
to come up with one the will satisfy the bulk of the science objectives
while maintaining a low enough fuel usage.

Check out the article!

                                           Brian S. Keller
-------

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

Date: 10 Oct 89 00:30:43 GMT
From: gem.mps.ohio-state.edu!uwm.edu!bionet!sdsu!polyslo!cosmos.acs.calpoly.edu![e-mail]  (Terrell Drinkard)
Subject: Hauling asteroids about

A question to Paul, or Nick, or even Henry:

How are we planning to haul these asteroids around?  Even  a
'small' one of 100m diameter is a bit largish to stuff into a
shuttle cargo bay, obviously.  So, are we anticipating some
enormous tow vehicle?  Or mounting rocket motors on the asteroid
itself?  Or [tacky idea follows] use nukes to redirect the orbit?

I can't see us having the capability to give more than a minimal
amount of delta V to a rock anytime soon.  Lets face it, a 100m
diameter rock masses oodles more than a shuttle (the light stony
ones run on the order of a million metric tons, or so says my HP).
And who wants those?  As I understand it, we want the nickel-iron
ones.

But, given the fuel and basic engine technology that would allow
this sort of manipulation what sort of control problems would the
crew encounter?  Just taking the spin off of such an object would
be a sizeable undertaking.  And then compensating in real time for
the center of thrust not running directly through the center of
mass will be no small challenge.

Just asking...

Terry

Disclaimer et la Signaturo:
Hell no, I'm not responsible for what I say!  If everyone were
responsible for what they said, we'd have had a balanced budget in
1984.

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

Date: 9 Oct 89 13:01:58 GMT
From: rochester![e-mail]  (Paul Dietz)
Subject: Re: The Moon vs. My Backyard

In article <[e-mail]> [e-mail] (nick szabo) writes:

>>Asteroids would be better, sure, but we haven't
>>got any lying around so conveniently.
>
>There are several discovered, and probably dozens of undiscovered, asteroids
>closer energy-wise than the Moon.  For a tiny, tiny fraction of this
>lunar base cost--less than 1%!--we could find these asteroids and
>characterize their surfaces.  Let's start doing the arithmetic!

Actually, there are estimated to be roughly 100,000 near earth
asteroids > 100 meters in diameter that are closer than the moon,
delta-v-wise.  The earth is in the middle of an asteroid swarm.

    Paul F. Dietz
    [e-mail]

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

Date: 9 Oct 89 06:18:35 GMT
From: jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: The Moon vs. My Backyard

In article <[e-mail]> [e-mail] (nick szabo) writes:
>...  Volatiles (hydrogen, nitrogen,
>etc.) are very rare or nonexistent...

With the *possible* exception of volatiles frozen at the lunar poles.

(For those who haven't seen this particular issue raised before...)
Volatiles do get onto the Moon now and then, when comets hit the Moon.
The question is, do they stick around?  There are probably areas at the
lunar poles that are permanently in shadow, since the Moon's axis is
fortuitously almost perfectly perpendicular to the ecliptic.  With luck
those areas could form nice "cold traps" for volatiles.  There are complex
arguments back and forth about how long volatiles would last there, but
overall it doesn't seem like polar volatiles can be ruled out without
going and looking for them.  This can be done from orbit, with the right
instruments.  Various lunar-polar-orbiter projects have been proposed by
NASA -- the latest is a proposal to use backup Mars Observer hardware --
but none has yet been seriously funded.  The Space Studies Institute is
now in the early stages of trying to do it as a private project (the RFP
went out a few months ago).
--
A bit of tolerance is worth a  |     Henry Spencer at U of Toronto Zoology
megabyte of flaming.           | uunet!attcan!utzoo!henry [e-mail]

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

Date: 9 Oct 89 06:31:23 GMT
From: jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: The Moon vs. My Backyard

In article <[e-mail]> [e-mail] (nick szabo) writes:
>(NB1: liquid oxygen accounts for less than 20% of the mass of payloads
>launched into space...

Rocket fuel in general, however, is 50% or better.  Cheap LOX in space
would make a lot of UDMH/N2O4 systems switch to LOX/LH2 instead.

>Liquid hydrogen, the only other major "raw material"
>used in space, cannot be found on the Moon...

Barring volatiles at the poles, yes.  But it's only about 15% of the mass
of LOX/LH2 at the usual rocket mixture ratio.

>Both of these could be replaced
>within the next 20 years for most uses by solar or nuclear electric power.

Um, Nick, I'd be interested to see how you get reaction mass out of a solar
or nuclear electric system; you'll still need fuel, although perhaps less.
There will also be problems with things that want high thrust.  (For example,
most satellites going to high orbit would prefer not to spend weeks working
their way up through the Van Allen belts with low-thrust engines.)

>There are several discovered, and probably dozens of undiscovered, asteroids
>closer energy-wise than the Moon.  For a tiny, tiny fraction of this
>lunar base cost--less than 1%!--we could find these asteroids and
>characterize their surfaces...

We need to know about their interiors, not just their surfaces.  Pointing
a telescope at the Moon is no more costly than pointing one at an asteroid,
but it doesn't tell us what we need to know.

>>I say we colonize the moon as soon as
>>we can figure out what's there.
>
>Really?  What if we find out there's nothing there?

You mean the way Columbus found out there was nothing in the Americas?
(No ":-)" -- he wanted spices, not savages and wilderness.)

>We _have_ mapped the Moon pretty well...

Look at the geochemical maps.  No we *haven't* mapped the Moon well, at all.
(The geochemical maps are a few thin stripes of data across lots and lots of
totally unknown territory.)

>and we haven't found _any_ good locations.  No concentrated ores, no
>volatiles, nothing of value.

How many concentrated ores would you find in half a dozen random samples
from the surface of small areas of, say, Texas?  Especially if you chose
the areas primarily for safe helicopter landings, rather than geological
interest?

>There are many, many other locations in the solar system.  How about let's
>go take a look at them?

No objection -- but let's not pretend that none of those interesting
locations are on the Moon.  We don't know that.
--
A bit of tolerance is worth a  |     Henry Spencer at U of Toronto Zoology
megabyte of flaming.           | uunet!attcan!utzoo!henry [e-mail]

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

Date:     Mon, 9 Oct 89 15:07 EDT
From: <[e-mail]>
Subject:  Galileo--- history repeats itself


  Wasn't it the Christics who persecuted Galileo hundreds of years ago anyway?
I think the Pope, in the infinite speed of Vatican justice, just forgave him
for sticking to his data and not popular propaganda.  Although I believe they
made him deny the truth to keep from being burned as a heretic, at the end.

        I'm amazed Columbus got funding at all.  I suppose he left port
before the Holy Enforcement Squad kept him from going off the edge of the
world, "where no mortal man was meant to be", or some nonsense.  Every age
has its groups that would prevent pursuits into the unknown, I guess.

        "The meek shall inherit the Earth..." Fine.  They can have it, the
rest of us can have whats left.  Someone give Donald Trump a copy of "The Moon
is a Harsh Mistress" and a letter appealing to his grand ego.  Private
enterprise might be the only way anything will ever get done.  Just spouting
off at a tangent.

                        Korac MacArthur
                        [e-mail]

"Death before Disclaimer!"

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

Date: 10 Oct 89 03:45:21 GMT
From: watmath!looking![e-mail]  (Brad Templeton)
Subject: UPI space & shuttle coverage available free in biz.clarinet.sample

For the next week or so, the group clari.tw.space, with coverage of
the space shuttle mission, will be fed for free to the group
biz.clarinet.sample.   The biz distribution is available on many backbone
sites, such as uunet.   You may wish to subscribe to that group for
space coverage.
--
Brad Templeton, ClariNet Communications Corp. -- Waterloo, Ontario 519/884-7473

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

Date: 10 Oct 89 02:07:05 GMT
From: rochester![e-mail]  (Paul Dietz)
Subject: Re: Hauling asteroids about

In article <[e-mail]> [e-mail] (Terrell Drinkard) writes:

>How are we planning to haul these asteroids around?

To start, at least, we wouldn't move them around.  We'd extract
some material at the asteroid and return it to earth orbit.

>And who wants those?  As I understand it, we want the nickel-iron
>ones.

Actually, the carbonaceous asteroids would also be desirable.  They
are thought to contain abundant volatile elements, from which one can
make reaction mass.  Also, many NEAs may be extinct comets
(Shoemaker's estimate was 60%, I think).

I imagine mining an asteroid with an unmanned vehicle.  It would be
propelled by a small nuclear thermal rocket.  At the asteroid, it
would be anchored to the surface, perhaps with three or four
penetrators with cables.  Winches would enable the vehicle to be
pulled over the asteroid surface.  A scoop or crusher of some kind
(carbonaceous meteorites are observed to be rather weak) would move
material into a chamber.  A gas would be heated in the reactor and run
over the material at high temperature.  The result would be a mixture
of gases -- water, oxides of carbon, hydrogen, methane, nitrogen, etc.
Some on-line chemical processing would convert the gas to something
storable (water? methanol?) for return to earth orbit.

Processing of metal asteroids would be similar, except that the
carbonyl process would be used.

When the storage tanks are full, the vehicle would return to eccentric
earth orbit using aerocapture.  For properly chosen asteroids the
delta-v to return to earth is much less than 1 km/s, perhaps as small
as 0.1 km/s.  From eccentric earth orbit the delta-v to go to another
asteroid can be quite small, less than 2 km/s.

    Paul F. Dietz
    [e-mail]

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

Date: 9 Oct 89 18:20:10 GMT
From: thorin!alanine![e-mail]  (Jonathan Leech)
Subject: Re: The Sad Tale of Galileo, Centaur, and the Invincible 'Nauts

In article <[e-mail]> [e-mail] (Nick Szabo) writes:
>This story cannot be repeated enough times.  Originally Galileo was supposed
>to launch on the Shuttle in early 1986 with a Centaur upper stage
>powerful enough to go straight to Jupiter.

    Actually, Galileo was originally supposed to launch on the Shuttle
in 1982. I was at a JPL conference back then, at which Bruce Murray
mentioned in passing that Galileo should have been on its way at that
time :-(
--
    Jon Leech ([e-mail])    __@/
    "A compact set can be controlled by a finite police force no
     matter how dumb." H. Weyl ca. 1938

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

Date: 9 Oct 89 15:51:47 GMT
From: sei![e-mail]  (Robert Firth)
Subject: Re:  Happy Birthday, Robert Goddard and Konstantin Tsilkovsky.

In article <[e-mail]> [e-mail] (Robert Firth) writes:
>My (Russian produced) digest of Tsiolkovsky's writings ('Man in the Cosmos')
>has the 4 October date.

***RETRACTION***

I really should learn to read enough text before shooting off my
mouth.  The cited book says no such thing; I misinterpreted a
sentence in the translator's introduction.  I've just gone off
and checked two other references, and they agree with Henry's
posted date (5 Sept old style / 17 Sept new style).

Sorry

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

End of SPACE Digest V10 #135
*******************