Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V16_4/V16NO454.TXT

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Date: Tue, 13 Apr 93 05:19:40
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V16 #454
To: Space Digest Readers
Precedence: bulk


Space Digest                Tue, 13 Apr 93       Volume 16 : Issue 454

Today's Topics:
  ASAT wasn't orbital (was Re: Question- Why is SSTO  Single Stage)
                          Astronomy Program
                   Civilian use of Russian missiles
                   Clementine Science Team Selected
                      Did any DC-X gifs show up?
                         The world of null-a
             Two-Line Orbital Element Set:  Space Shuttle
             What if the USSR had reached the Moon first?
          What is the significance of the name "Clementine?
                   Why is SDIO doing "Clementine"?
            Why is SDIO doing "Clementine"? (part #2 of 6)

    Welcome to the Space Digest!!  Please send your messages to
    "[e-mail]", and (un)subscription requests of the form
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    (BITNET), rice::boyle (SPAN/NSInet), utadnx::utspan::rice::boyle
    (THENET), or [e-mail] (Internet).
----------------------------------------------------------------------

Date: 12 Apr 93 17:51:44 -0600
From: Bill Higgins-- Beam Jockey <[e-mail]>
Subject: ASAT wasn't orbital (was Re: Question- Why is SSTO  Single Stage)
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Gary Coffman) writes:
> It would seem that a first stage built like an airplane, and
> operated like an airplane, that carried an orbital stage, built like
> an airplane and operated like an airplane, with an easy mate design would
> make orbital flight cheaper and more effective than a SSTO requiring
> ultralight structures and finicky maneovers just to get to orbit and
> back. MX has been launched from a C5, and neither system was designed
> for that.

Really?  I'd pay to see that!

> A F16 has carried an orbital ASAT rocket.

Whoops, factual error.  The U.S. experimental ASAT was an air-launched
rocket that went to the *altitude* of low-orbit satellites.  It got
nowhere near the *speed* required to go into orbit-- if it failed to
hit its target, it would have fallen right back to the ground.
Nitpicking, it was carried on an F-15, not an F-16.  (If I'm wrong,
I'll hear about it!)

     O~~*           /_) ' / /   /_/ '  ,   ,  ' ,_  _           \|/
   - ~ -~~~~~~~~~~~/_) / / /   / / / (_) (_) / / / _\~~~~~~~~~~~zap!
 /       \                          (_) (_)                    / | \
 |       |     Bill Higgins   Fermi National Accelerator Laboratory
 \       /     Bitnet:     [e-mail]
   -   -       Internet:  [e-mail]
     ~         SPAN/Hepnet:      43011::HIGGINS

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

Date: 9 Apr 93 04:27:18 GMT
From: kevin marcus <[e-mail]>
Subject: Astronomy Program
Newsgroups: sci.space

Are there any public domain or shareware astronomy programs which will
map out the sky at any given time, and allow you to locate planets, nebulae,
and so forth?  If so, is there any ftp site where I can get one?

Please reply by email to [e-mail]
thanks.

--
 -=+> Kevin Marcus, Virus Researcher.   Author: TSCAN, RE-xxx, MICHEX, STONEXT
      [e-mail]           (619)/457-1836, 3-2400 baud, 24 hours.
      Comp. Sci. Major, University of California, Riverside.

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

Date: Mon, 12 Apr 1993 23:47:22 GMT
From: Michael Moroney <[e-mail]>
Subject: Civilian use of Russian missiles
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Mark Prado) writes:
>>The idea is that instead of destroying many of these missiles, as
>>we are currently planning to do, we could instead launch things
>>into orbit...

I think the Russians are actually doing some of that.  I read something
about a launch of a satellite by Russia on a converted ICBM, and in
addition they launched an ICBM at Washington State (actually the offshore
ocean).  Instead of a nuke it carried some sort of items to celebrate
US-Russia peace and I think it was intended as an advertisement "we have
these rockets, we now can do more than launch nukes, let us launch your
satellites"

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

Date: Mon, 12 Apr 1993 20:35:25 GMT
From: Dave Tholen <[e-mail]>
Subject: Clementine Science Team Selected
Newsgroups: sci.space,sci.astro

Doug S. Caprette writes:

>> Clementine

> Why is a civilian project being spoinsored by a military agency?

It isn't a civilian project.

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

Date: Tue, 13 Apr 1993 01:58:30 GMT
From: Douglas R Fils <[e-mail]>
Subject: Did any DC-X gifs show up?
Newsgroups: sci.space

sci.space,
    Did any GIFS show up from the roll out of the DC-X?
I recall someone mentioning that they might be able to get some
and I have been away from the net for a few days and thought
I might have missed any notice.

Thanks much for the time...
and thanks to anyone who has made up and posted gifs of this
important event!

take care
Doug

--

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

Date: Mon, 12 Apr 1993 23:09:30 GMT
From: nathan wallace <[e-mail]>
Subject: The world of null-a
Newsgroups: sci.space

In article [e-mail], [e-mail] (Tom) writes:
>>>Does anyone have any info on the apparent sightings of Vulcan?
>
>>From memory Vulcan was an attempt to account for the precession
>>of the axes of the orbit of Mercury in the late 19th century. The
>>effect has now been full explained thanks to the Theory of
>>Relativity. In fact Mercury's orbit was one of the first
>>confermation of relativity. Vulcan was supposed to have been
>>observed by a somewhat dubious 'gentleman' astronomer who kept
>>his notes on a plank of wood, and used plane as an eraser.
>
>Another legend with the name Vulcan was the planet, much like Earth,
>in the same orbit, but on the other side of the Sun.  I don't know
>the origin or age of this legend, though.  Maybe someone else can fill
>in the people and time this legend comes from.
>
>-Tommy Mac
>-------------------------------------------------------------------------
>Tom McWilliams 517-355-2178 wk   \\ As the radius of vision increases,
>[e-mail] 336-9591 hm \\ the circumference of mystery grows.
>-------------------------------------------------------------------------

I believe this showed up in an ancient (relatively :)) sf book called "the world
of null-a". it was about a planet orbitting exactly opposite earth, but in
the same orbit, and thus always invisible to astronomers on the other side of
the sun. John Norman's GOR series is set on such a world.

If anyone remembers my lagrange question from a couple of weeks ago,
it was to settle this exact point, namely whether a world *could* exist for
any length of time in an "antipodal" position to another planet. (apologies
if that term is not exactly correct.) according to the people i've asked,
it couldn`t. Too bad.

If there was an older legend these books were based on, I'd love to
hear about it too!

---
C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/
C/    Nathan F. Wallace                   C/C/           "Reality Is"         C/
C/    e-mail: [e-mail]   C/C/    ancient Alphaean proverb    C/
C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/


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

Date: Tue, 13 Apr 1993 04:31:55 GMT
From: TS Kelso <[e-mail]>
Subject: Two-Line Orbital Element Set:  Space Shuttle
Newsgroups: sci.space

The most current orbital elements from the NORAD two-line element sets are
carried on the Celestial BBS, [phone], and are updated daily (when
possible).  Documentation and tracking software are also available on this
system.  As a service to the satellite user community, the most current
elements for the current shuttle mission are provided below.  The Celestial
BBS may be accessed 24 hours/day at 300, 1200, 2400, 4800, or 9600 bps using
8 data bits, 1 stop bit, no parity.

Element sets (also updated daily), shuttle elements, and some documentation
and software are also available via anonymous ftp from archive.afit.af.mil
(129.92.1.66) in the directory pub/space.

STS 56
1 22621U 93 23  A 93100.58333332  .00060906  00000-0  17653-3 0   103
2 22621  57.0037 168.0276 0004614 270.7909 289.6873 15.92482227   371
--
Dr TS Kelso                           Assistant Professor of Space Operations
[e-mail]                    Air Force Institute of Technology

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

Date: 12 Apr 93 21:17:42 GMT
From: ChaOs <[e-mail]>
Subject: What if the USSR had reached the Moon first?
Newsgroups: alt.history.what-if,sci.space

In article <dxb105.734495289@virgo>, [e-mail] (David Bofinger) writes:
> [e-mail] (ChaOs) writes about the military application
> of a lunar base:
>
>> Well, ever read (for example) Robert Heinlein's _The Moon is a Harsh
>> Mistress_?  A lunar colony was able to do a frightening amount of
>> damage just by throwing rocks at earth.
>
> This made sense in the book because it was an improvised weapon -- the
> rebel colonists didn't own any nukes (though they did own the human
> race's best computer, for no obvious reason).

Just to get off the subject a bit, having _one_ computer that controlled just
about everything on the Moon from life support to transportation to calculating
flight paths means that the computer would _have_ to be tremendously complex.
That's why Mike woke up in the first place.  Now back to the topic:

> But everything they did
> could far more easily have been acheived by nuclear-tipped ICBMs
> launched from Earth. It's not that lunar bases can't attack the Earth,
> but in a world where exterminating most of the human race can be done
> fairly cheaply its hard to see what capabilities it adds.

The purpose of the military is not to exterminate the entire human race - or at
least it shouldn't be.  Going with the rocks example:

1) No radiation.  Destroyed places are not sealed off forever, there are no
   adverse effects on surrounding populations, etc.  Also, it's more humane,
   because it won't cause cancer, birth defects, etc.
2) No fallout.  This is generally regarded as good, because it means your own
   side won't get offed by your weapons.
3) Harder to affect in flight.  Antimissiles can knock out nukes, but a rock?
   It might push it off course, but it'd still hit somewhere.

Also, a lunar base could be used to supplement spy satellites, etc.  Why?

1) As someone else pointed out, it's harder to destroy.
2) No problems with decaying orbits.
I'm sure there are others.  Not being an expert in optics, I don't know if we
have the technology to make this viable, but if we're postulating a moon-base
anyway...

--
[e-mail] - Official generic .sig.  Under 4 lines, under 80
columns, no Amiga checks, no witty quotes, no maps of Australia, no asterisks,
no ASCII art, no disclaimers or anti-flame requests, and one spelling errer.

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

Date: Mon, 12 Apr 1993 22:38:27 GMT
From: James Thomas Green <[e-mail]>
Subject: What is the significance of the name "Clementine?
Newsgroups: sci.space

What is the significance of the name "Clementine? (oh my
darling :-)

Is it the name of some goddess related to the moon?  The wife of
the cheif scientist?  No meaning at all?


/~~~(-: James T. Green :-)~~~~(-: [e-mail] :-)~~~\
|                                                               |
|          Support Mental Health, oR i'LL kILL yOu!?!?!         |

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

Date: Tue, 13 Apr 1993 00:28:00 -0500
From: Mark Prado <[e-mail]>
Subject: Why is SDIO doing "Clementine"?
Newsgroups: sci.space

OK, here goes.  <deep breath>

I worked for years in direct support of SDIO (which was a short
walk
from my office).  I helped manage the Delta 180 and Delta 181
missions, and did long range planning.  I'm a physicist, and my
main specialization at the time was evaluating sensors, though I
found myself in lots of things.  I resigned in 1987 to do other,
unclassified and less stifling things (though I now find myself
consulting primarily to the State Dept ...)

The following is a Small Business Innovative Research (SBIR)
proposal
which my company submitted in 1988, and which I've edited a bit
so
that you or your associates could use it.  (Since I'm the
President
and CEO of the primary, I'm not in deep yogurt over doing this,
though I hope none of my associates are the kind to object to this
...)

Any response/growls should go to   [e-mail]
and NOT to the address in the header of this message.
(In deed, let's ping to see who gets it.)

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

[                        PERMANENT
           Program to Employ Resources of the Moon
                   and Asteroids Near Earth
                       in the Near Term                   ]

Abstract of proposal

Much of the BMD mass needed for delivery TO ORBIT is
unsophisticated
(e.g., shielding, fuel propellant, structural materials) and thus
could
feasibly be produced from the material of certain Near-Earth
Asteroids
and/or lunar materials.  Recent studies conclude that this
material,
ALREADY in space, could be delivered to Earth orbit in quantities
dwarfing what could feasibly be launched from Earth, at
dramatically
reduced costs per pound.  (After all, the European settlers of
America
didn't bring everything with them -- they used indigenous
resources.)
Delivery of Near-Earth asteroidal material would require a
simple,
small low thrust vehicle (an orbit-to-orbit "tug").  The delta-v
required is as small as 0.1 km/sec for known near-Earth asteroids
such
as 1982DB (versus 8.0 km/sec for Earth launch and a large,
complex
vehicle fighting Earth's threatening gravity).  One 100-ton
spacecraft
with in-situ propellant production capability could retrieve
10,000
tons of asteroidal material.  The Phase I effort would define
potential
products and logistical needs, but focus upon the costs and
equipment
required to make certain products such as shielding and fuel
propellants.  Phase II work could develop or verify particular
processes in the laboratory.


 Table of Contents

1.  Cover Sheet and Abstract
2.  Identification and Significance of the Opportunity
        Products from Near-Earth Asteroidal and Lunar Materials
        Costs -- Economic and Technological Comparison,
            Nonterrestrial vs. Earth-Launched Sources of Material
        Compositions and Processing of Nonterrestrial Materials
3.  Technical Objectives and Work Plan
4.  Key Personnel, Facility Resources, and Consultants
5.  Cost Proposal


Figure 1:  The following products could be commercial spinoff
           products from a program to utilize nonterrestrial
           materials for defense uses -- for popular support


o  Fuel propellant for transporting satellites from low orbit to
     geostationary orbit  (currently requires two tons of fuel
     launched from Earth per ton of satellite to low orbit)

o  Multi-satellite platforms

o  Shielding for space stations

o  Construction materials for walls, beams, and other structural
     members for orbit based facilities

o  Silicon solar cells and silicon semiconductors

o  Large communications antennas

o  Space-based radar to track aircraft

o  Cobalt and platinum group metals from asteroidal materials
     (one product worth returning to Earth)

o  Settlements for corporate communities (with 24 hour sunlight,
      and healthy artificial gravity by rotating huge habitat for
      centrifugal force)

o  Solar power satellites for beaming energy to Earth (longterm)

o  Giant (revolutionary) telescopes for scientific study

        - radio telescopes
        - optical telescopes
_____________________________________________________________


Figure 2:  The following massive but simple products could be
           made from space resources and used to defend any
           space-based operation:

o  Shielding using layers of steel, concrete, ceramics, and sand

        - SDI systems
        - non-SDI assets

o  Propellant

      - orbit-to-orbit transfers of systems and supplies
      - stationkeeping propellants
      - maneuverability for:
             survivability
             better reconnaissance
             better battlefield support
             quickly deploying spare satellites
             adaptive constellations
             intercept

o  Portions of electric power systems

      - fuel to generate burst power (turbogenerator, MHD)
      - radiation shields around nuclear fuel sources
      - structural arrays for solar cells, survivable

o  Energy storage systems

      - Nickel-Hydrogen batteries
      - Steel Flywheels
      - Fuel Cells

o  Cryogenic liquids for cooling of systems

      - optics and sensors
      - weapons systems
      - power generators (cryogenic fuel)
      - IR signature control (e.g., cooling front side)

o  Electronic countermeasure antennas and power sources

o  Space based radar (for global monitoring of aircraft, tanks)

o  Particles for interactive discrimination (RV's vs. decoys)

o  Space stations, garages, and other facilities

o  Decoys

o  Inertial platforms for rapid retargeting and precision
    pointing with minimum structural vibration




      2. Identification and Significance of the Opportunity

Technology advances may allow the Free World to consider creating
new kinds of space based defense systems which would have the
capability to change the nature of warfare, both strategic and
tactical, in such a way as to enhance the security of defense-
oriented nations.

Utilization of material already in space -- from Near-Earth
Asteroids and/or from the lunar surface -- may be pivotal to
making such concepts economically feasible, survivable, robust,
defense-dominant, and politically realistic.

The Strategic Defense Initiative (SDI) would require a mass of
material in Earth orbit much greater than any other official
program, past or currently planned.  It is debatable whether the
necessary material for a survivable and robust system could
realistically be delivered into Earth orbit at an attractive cost
using current and projected Earth launch vehicles, especially
given budgetary constraints and other defense spending
priorities, not even considering the ever present technical
difficulties associated with large Earth launch vehicles.

Much of the mass needed in orbit for a completely operational SDI
system would be relatively unsophisticated (e.g., shielding, fuel
propellant, burst power fuel) and thus could feasibly be produced
from the material of certain Near-Earth Asteroids and/or from
lunar materials.

As stated in the abstract, recent studies conclude that Near-
Earth Asteroidal material and possibly lunar material could be
delivered to Earth orbit in quantities dwarfing what could
feasibly be launched from Earth, at dramatically reduced costs
per pound (in bulk).  Delivery would require a simple, small low
thrust vehicle (an "interorbital tug"), and the delta-v required
to bring material back is as small as 0.1 km/sec for known Near-
Earth Asteroids (versus 8.0 km/sec for Earth launch and a large,
complex vehicle fighting Earth's threatening gravity).

Conservative studies estimate that a 100-ton asteroid-recovery
vehicle (including fuel propellant) launched from low Earth orbit
would be able to retrieve 10,000 tons of a near-Earth asteroid
such as 1982-DB, for a mass payback ratio of approximately 100,
assuming in-situ propellant production capability.  After the
first return of cargo, the spacecraft would be reusable.

In 1983, the Defense Technologies Study Team (DTST), headed by
Dr. James C. Fletcher, met with the National Academy of Sciences
and the National Science Foundation to review new ideas in BMD
technology.  They reported on "[t]wo new ideas that warrant
serious attention and fiscal support in the years 1984-1989 ...
The first of these was the possible use of extraterrestrial
resources to provide large amounts of mass in Earth orbit ...",
primarily to satisfy survivability needs.  The DTST later
sponsored a workshop to further explore the issue.   "The group
concluded that extraterrestrial materials may provide the
required mass at costs competitive with or significantly cheaper
than options requiring launch from Earth's surface ...  Material
from the lunar surface or from nearby asteroids can be brought to
the vicinity of Earth for a much lower energy budget than
launching from Earth's surface - 1 to 3 orders of magnitude
less."  However, the funding suggested was not officially
allocated.

The Soviet Phobos lander currently under construction for launch
in the
early 1990's will effectively be landing on an asteroid to sample
its minerological and elemental composition and its physical
consistency.  (Phobos is an asteroid moonlet of Mars, with
practically no surface gravity.)  The Soviets are cooperating
with 14 nations on this project, most of these nations being
western technological powers.

Also, consistent with President Reagan's stated consideration of
sharing SDI technology with the Soviets, it may be conceivable to
negotiate with the Soviets a sharing of technology used in
retrieving Near-Earth Asteroidal and lunar material, and to
engage in a cooperative effort.

As stated in a 1986 report of the NASA Advisory Council, which
devoted 30 pages to the topic:  "As other advisory groups have
pointed out, large-scale human activities in space will, in time,
become an integral part of Earth's economy.  The use of near-
Earth resources, obtained from the Moon and nearby asteroids,
will be essential.  The ability of the U.S. to be prepared to
act, when the time comes, depends on our preparedness, including
having in hand a scientific survey of the resources that are
potentially available in space."  However, the strong
recommendations of the NASA Advisory Group have failed to
produce significant additional support from within NASA due to
competing interests in an era of declining spending.

As of this day, January 6, 1988, there has yet been an official
committment to this project, though there are numerous groups
doing work in this area with funding from sources largely unknown
to us.  Further, there is apparently no central databank of
information available to new researchers interested in this
field, nor is there an available report establishing a clear
foundation for future development.

This proposal is to justify support for a Phase I evaluation of:

1. potential products from near-Earth asteroidal material and
     lunar material that would help create survivable and
     robust space based defense systems and civilian products;

2. key materials processing issues for making the above products;

3. other logistical, equipment and technology needs; and

4. economic factors in retrieving and processing materials for
     manufacturing valuable defense system components.

[continued in next message]

 * Origin: PerManNet Communications, Washington D.C., U.S.A.
(1:109/349.2)

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

Date: Tue, 13 Apr 1993 00:29:01 -0500
From: Mark Prado <[e-mail]>
Subject: Why is SDIO doing "Clementine"? (part #2 of 6)
Newsgroups: sci.space

Product #1:  Shielding

It would be difficult to acquire a capacity to attack and destroy
BMD or other defense satellites protected by several feet of
armor consisting of layers of steel, "lunarcrete", ceramic,
fiberglass, and sand.  This would lead to a stable strategic
situation, instead of a space based arms race, by making the
defense dominant.  The great expense of attacking well protected
BMD satellites makes it extremely unlikely that a potential
adversary could acquire the ability to "punch a hole" in an SDI
system by destroying most or all of the BMD satellites in a
position to prevent ballistic missile attack, in a short enough
time to make such an attack practical.

Several layers of thick, laminated steel and fiberglass could
greatly enhance the survivability of satellites contained within
them.  While not impermiable, these shields would be immune to
most current threats -- multimegawatt directed energy weapons,
nuclear detonations more than a mile away, impact of co-orbiting
explosive projectiles up to several hundred pounds, and impact of
counterorbiting projectiles up to tens of pounds.

Survivability has a long military history.  There are four
primary methods of acheiving it:

        - concealment  (including decoys)
        - hardening  (e.g., shielding)
        - escape  (e.g., using propellant)
        - shoot-back  (e.g., using propellant and shrapnel)

Nonterrestrial materials (NTM) could provide shielding, decoy
shields, propellant for maneuverability, and possibly shrapnel
and energy stores for shootback systems.  (Regarding concealment,
low Earth orbit is an impossible environment to conceal a size-
able object from view.  Proliferating decoys would be necessary
to conceal valuable satellites.)  Electronic countermeasures is
an additional possibility, given enough power.  (Power is
discussed later in this proposal.)

It can be argued that we can employ reactive protection tech-
niques to thwart a specified threat, but the enemy can usually
develop and deploy a different type of threat which defeats the
reactive protection technique before significant advantage can be
gained, especially if the enemy is committed.  The best recourse
is a combination of shielding, decoys, maneuver, and shootback.

The only protection technique with a history of success against a
wide variety of threats - some not anticipated at the time of its
production - is to put thick pieces of strong material between
the threat and the target.  While any protection technique can be
defeated, thick armor is relatively difficult to penetrate and
thus requires the enemy to use expensive and large weapons which
he cannot afford in great quantities.  These heavy weapons are
much easier to find, attack ("shootback") or avoid than are
numerous lighter weapons.


Product #2:  Fuel Propellant

Large amounts of oxygen would be useful for rocket fuel.  Oxygen
is ubiquitous in nonterrestrial materials, averaging 42% of the
lunar crust and around 30% of many near-Earth asteroids, bound as
mineral oxides.  Because water is 86% oxygen by weight, 6-8 times
as much oxygen as hydrogen would be consumed in a hydrogen-oxygen
rocket engine.  In other words, 86% of regular rocket fuel is
oxygen and is abundant in asteroidal and lunar material.

Hydrogen is almost certainly abundant in near-Earth asteroids, as
is carbon.  Therefore, 100% of rocket fuel could be derived from
nonterrestrial materials.

These elements are extractable simply by heating the material,
using a small nuclear or solar oven.

Inexpensive propellant could enhance survivability by allowing
BMD satellites to perform significant orbit changes when under
attack.  These orbit changes could also be used to enhance
systems performance by allowing satellites to adjust their orbits
for maximum defensive effect, or to cover gaps left by
overwhelmed or destroyed satellites.

Orbital maintenance also requires fuel propellants.  A typical
satellite in low Earth orbit requires about 25% of its weight to
be stationkeeping fuel over a 5-year operational lifetime.
Pointing and tracking systems may require additional propellant.


Product #3:  Power Generation

In addition to use as fuel propellants, oxygen and hydrogen are
useful for electric power generation.

Large amounts of inexpensive oxygen and hydrogen or hydrocarbons
would provide an excellent fuel source for turbogenerators or
MHD/turbogenerator hybrid systems.  This would be very useful for
directed energy or electromagnetic launcher weapons systems,
space based radar, and electronic countermeasures.

Turbogenerators and MHD (magnetohydrodynamic) systems have the
advantages of being able to provide burst power on a moment's
notice, minimal housekeeping requirements, and simplicity in
design and operation.  Turbogenerators can be extremely compact
and simple power supply devices when fueled by combustible
liquids.  The availability of inexpensive oxygen could provide
abundant energy stores and reduce the operating costs of
currently envisioned systems.  (20 to 50 times as much oxygen as
hydrogen could be consumed in an oxy-hydrogen gas turbine.)

The cryogenic oxygen and hydrogen can also be used to cool
systems by circulating the fluid thru pipes enroute to the
combustor.



A robust defense is one which has the capability to react to
unanticipated threats, to react to more extensive threats than
were expected, and to be on alert whenever there is some
possibility of trouble.  All of these capabilities require large
amounts of propellants for maneuvering and power generation.  If
fuel is cheap, evasive maneuvers can be taken, systems warmed up,
or warning shots fired without the need to worry about running
out of propellant or power or running over budget.  Without low
cost fuel, there will be the temptation to sit tight in tense
situations - which could lead to being badly out of position,
unprepared and vulnerable when an attack is launched.


Other Products:

A prerequisite to considering a product to be made from
nonterrestrial materials is that the product must satisfy all of
the following criteria:

     - consist of elements known to be abundant in NTM
     - be simple to produce, requiring minimal machining
     - be in massive demand

Figure 1 lists the components of a space defense system which
might be feasible to produce from nonterrestrial materials.

Figure 2 lists potential civilian products, many of which are
important to national security.

Many of these products are basic structural items.

In addition to making space based defense systems feasible and
effective, space resources can also be used for products of
economic and cultural benefit, as well as for spreading free
societies beyond Earth's biosphere.  A significant public motiv-
ation for supporting SDI research is that there will inevitably
be commercial spinoffs of great value to our nation and mankind
from SDI technology and infrastructure.  Research into using
Near-Earth Asteroidal and lunar material would enhance this
public interest.  The projected rewards of creating a space based
economy, in terms of benefits from space based products, the
trade deficit and multi-billion dollar space exports, enhanced
security for the Free World, and the spread of free societies,
are immense compared with the cost and risk of the preliminary
R&D necessary to determine the feasibility of doing so.
Costs

Low Earth orbit (LEO) is much more energetically accessible from
"Near-Earth Asteroids" than either the lunar surface or Earth's
surface.  Table 1 compares transportation requirements from the
three candidate sources of material.  Figure 3 illustrates the
difference in propulsive requirements to leave the Earth or the
Moon with roughly equivalent payloads (two men in a gemini
capsule vs. two men in the lunar module).

_______________________________________________________________

Table 1:  Comparison of accessibility


Material source       Earth    Moon      Near Earth Asteroid
                                           (e.g., 1982DB)

Energy               2000      180                   1
Delta-V, km/s           8        2.4                 0.1
Mass of planet[oid]    81        1                  10^-18
_______________________________________________________________

The economics of delivering space resource derived manufactures
to Earth orbit have been discussed in a variety of contexts, as
has the possible utility of space resources for SDI.  However,
these analyses have not been performed in adequate detail to
confidently apply their positive results to calculating
approximate costs for providing shielding and propellants for SDI
like missions, nor have they been done in the depth required to
believably generalize their results and have some confidence that
the answers are meaningful.  The attendant issues could be
substantiated further by the proposed Phase I SBIR effort.

DoD-sponsored workshops have looked into utilizing nonterrestrial
materials (NTM) for SDI, and there are numerous recent NASA
studies into the issue.   Conservatively assuming production of
primarily fuel propellants, shielding, and structural materials,
the conclusions of these workshops and studies were that these
commodities might feasibly be produced from space resources for
much less than the cost of launching equivalent materials from
Earth, in a scenario of major demand such as a deployed SDI
system.  Despite positive reports, these concepts have not
received the requested follow-on funding and thus have not been
pursued much further.

It should be emphasized that nonterrestrial materials become more
economical than Earth sources only in scenarios where large
quantities of material are needed in a relatively few years.  A
large front-end investment is needed to initiate nonterrestrial
materials utilization.  After that one-time investment,
nonterrestrial materials will thereafter be available at lower
cost than Earth-derived materials.  The crossover point has yet
to be defined.  However, general statistics on the quantity of
SDI shielding mass and propellants needed may provide one single
legitimate application to justify evaluating the relative merits
of nonterrestrial materials utilization and estimating an
economic crossover point.

[continued in next message]

 * Origin: PerManNet FTSC <=> Internet gateway (1:109/349.2)

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

From: Bill Higgins-- Beam Jockey <[e-mail]>

Newsgroups: sci.space
Subject: Perishable food (was Re: Quick reaction shuttle)
Followup-To: sci.space.shuttle
Date: 12 Apr 93 17:02:01 -0600
Organization: Fermi National Accelerator Laboratory
Lines: 26
Message-Id: <[e-mail]>
References: <1q5381$[e-mail]> <[e-mail]> <1q7vki$[e-mail]> <[e-mail]> <1qage2$[e-mail]> <[e-mail]>
Nntp-Posting-Host: fnalf.fnal.gov
Summary: A possible solution to the food problem?
Sender: [e-mail]
Source-Info:  Sender is really [e-mail]

In article <[e-mail]>, [e-mail] (Josh Hopkins) writes:
> [e-mail] (Pat) writes:
>
> How difficult can it be to keep a
>>shuttle stacked,  and waiting for the occasional light weight
>>mission?
>
> Try impossible.  Or at least, not practical for the amount of money we're
> willing to spend.  For one thing, you'd be tying up a launch pad or VAB spot.
> For another, the shuttle doesn't have an infinite shelf life.  You can't keep
> the fuel in it forever (or the food for that matter).

Roger on the hydrazine and N2O4, Josh, but as for the food, surely
they could install vending machines in the Shuttle?

In a national emergency, I'm confident astronauts could subsist for a
week on peanut-butter cheese crackers.  After all, hackers do it all
the time.  (Although in times of real stress, I tend to fall back on
microwave popcorn.)

Bill Higgins, Beam Jockey              | "Enough marshmallows
Fermi National Accelerator Laboratory  | will kill you
Bitnet:           [e-mail]  | if properly placed."
Internet:       [e-mail]  | --John Alexander, leader of
SPAN/Hepnet:           43011::HIGGINS  | "disabling technologies"
 [*Aviation Week*, 7 Dec 1992, p. 50]  | research, Los Alamos

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End of Space Digest Volume 16 : Issue 454
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