Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/spacedig/v15_1/v15no126.txt

Internet Message Format | 1993-07-13 | 33KB

Date: Thu, 20 Aug 92 05:00:04
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #126
To: Space Digest Readers
Precedence: bulk


Space Digest                Thu, 20 Aug 92       Volume 15 : Issue 126

Today's Topics:
                    ACRV/Soyuz P # of Passengers
                      Deep-sea Diving on Europa
             Early Warning of missiles and meteo (2 msgs)
                           Electric Tethers
                          Home made rockets
                Shuttle (was: Private space ventures)
                        Soyuz as ACRV (2 msgs)
                       space industry (3 msgs)
             SPS feasibility / Astrophysical Engineering
superstrings & supralight (was SPS feasibility and other space development)
                       Weekly reminder for FAQs
                  What about Saturn?/Future not Past
           Will LAGEOS 2 Earth satellite have a plaque too?

    Welcome to the Space Digest!!  Please send your messages to
    "[e-mail]", and (un)subscription requests of the form
    "Subscribe Space <your name>" to one of these addresses: listserv@uga
    (BITNET), rice::boyle (SPAN/NSInet), utadnx::utspan::rice::boyle
    (THENET), or [e-mail] (Internet).
----------------------------------------------------------------------

Date: 19 Aug 92 15:27:32 GMT
From: Gary Coffman <ke4zv!gary>
Subject: ACRV/Soyuz P # of Passengers
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Allen W. Sherzer) writes:
>In article <[e-mail]> [e-mail] (Gary Coffman) writes:
>
>>The problem with this scenario is *the service isn't provided*. That
>>can't be tolerated when there are crews up there. So the government
>>*will* pay, and the contractor knows it.
>
>Does the word 'comeptition' ring a bell? If GD says "Ah Uncle Sam, we
>got you by the balls now!" then Uncle Sam replies: "Screw you, I'm taking
>my buisness to Martin Marrietta".

And wait how many years for MM to develop a comparable system? *Time*
critical missions go on the first *available* transport, not on a
hypothetical system that promises to be cheaper by and by. Once Fred
is up there, all resupply flights become *time* critical. That gives
the current contractor enormous leverage. There is no market for *two*
HL systems today, only Fred, and a possible return to the Moon. Winner
takes all.

Gary

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

Date: 19 Aug 92 13:05:03 GMT
From: Rui Sousa <[e-mail]>
Subject: Deep-sea Diving on Europa
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Stuart Birkett) writes:

   Path: pinkie!dec4pt.puug.pt!inesc.inesc.pt!mcsun!uunet!elroy.jpl.nasa.gov!usc!sol.ctr.columbia.edu!eff!ibmpcug!pipex!demon!cix.compulink.co.uk!sbirkett
   Newsgroups: sci.space
   From: [e-mail] (Stuart Birkett)
   Reply-To: [e-mail]
   Date: Sun, 16 Aug 1992 18:25:09 +0000
   Sender: [e-mail]
   Lines: 13


>      Marc Barrett writes.......


>     > Many scientists and science fiction writers have speculated
>     > about the possibility of life in the depths of the oceans on
>     > Europa.

>   What are the oceans of Europa composed of?

>   Stuart......

Mostly water, based on what the Voyagers have seen on Europa's surface
(water ice). The ice crust should be a couple of kilometers thick, so
explorers should look for cracks or they would have to dig a lot... :-)

Rui Sousa
--
*** Infinity is at hand!                               Rui Sousa
*** If yours is big enough, grab it!                   [e-mail]

                All opinions expressed here are strictly my own

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

Date: 18 Aug 92 07:20 PDT
From: Mark Goodman <[e-mail]>
Subject: Early Warning of missiles and meteo
Newsgroups: sci.space

To:    sci.space From:  Mark Goodman ([e-mail]) Re:
Meteoroid Detection Date:  18 Aug 1992

The question was asked whether U.S. ballistic missile early
warning systems could detect 1 meter meteoroids.  I think the
answer is yes, but it depends.

U.S. early warning radars operate by scanning across the horizon
for missiles or components (most likely upper stages and buses,
which send MIRVs on their independent trajectories) as they rise
above the horizon, at a distance of several thousand kilometers.
These objects have radar cross-sections of up to a few square
meters.  At that distance, they spend several tens of seconds in
the radar's fan, and the radar has several opportunities to view
them.  By adding the signals from separate radar sweeps, the radar
can achieve the high signal-to-noise ratio needed to detect
missile launches with high confidence and without significant risk
of false alarms.

The return signal from the radar scales as R^-3.  (R^-2 each for
difraction of the direct and return signals, and an extra R to
reflect the fact that objects farther away more at a slower
angular rate and spend more time in the radar fan, allowing a
larger integrated signal.

Meteoroids also travel faster than ballistic missiles -- tens of
km/sec compared to up to 7 for missiles, at least until they get
vey low in the atmosphere and are below the radar fan -- so
theradar won't have as much time to look.  The United States has a
PAVE PAWS radar in Georgia for warning of SLBM attack, which I
think had a good chance of seeing a meteoroid off Daytona Beach.

Two points of potential confusion.  It is said that radars can
objects the size of a grapefruit (or perhaps smaller) in orbit.
That is only when the objects pass nearly overhead in low orbits,
a few hundred kilometers away.  This also allows longer times for
tracking.

Also, over-the-horizon radars are irrelevant to this discussion.
They do not have anything like the sensitivity required to see a
meteoroid against the backscatter of the Earth's surface.

+-----------------------------+-----------------------------+
|       Mark W. Goodman       | What a terrible thing it is |
| [e-mail] -- econet | to lose your mind.          |
| [e-mail]  |                             |
+-----------------------------+-----------------------------+

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

Date: 19 Aug 92 15:34:26 GMT
From: Doug Mohney <[e-mail]>
Subject: Early Warning of missiles and meteo
Newsgroups: sci.space

In article <[e-mail]>, Mark Goodman <[e-mail]> writes:

>Meteoroids also travel faster than ballistic missiles -- tens of
>km/sec compared to up to 7 for missiles, at least until they get
>vey low in the atmosphere and are below the radar fan -- so
>theradar won't have as much time to look.  The United States has a
>PAVE PAWS radar in Georgia for warning of SLBM attack, which I
>think had a good chance of seeing a meteoroid off Daytona Beach.

I don't even know if they run PAVE PAWS 24 hours/day x 7 days/week anymore.
Budget cuts and our friends the Russians' ya know...

                 Support U.N. military force against Serbia

  -- >                  [e-mail]                        < --

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

Date: 19 Aug 92 15:13:00 GMT
From: "R. Cage" <[e-mail]>
Subject: Electric Tethers
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Mike Evert) writes:
>I have a question about the possibilites of an electric tether system
>like that the recent shuttle flight attempted to test.
>
>As I understand it, if a current is put into the tether, then that
>would cause the tether and spacecraft to gain kenetic energy and rise
>to a higher orbit.  The opposite will happen if current is drawn from
>the tether.  Would the acceleration always be in one direction and its
>reverse only?  I don't know if this would be in the direction of orbit
>or perpindicular to magnetic field.  Is it possible to use the tether
>for lateral motion?

Not really.  The limitation is due to simple physics:

1.)    The force is due to the I x B interaction between the
    current in the conductor and the magnetic field.  The
    vector cross-product means that the force must be
    perpendicular to the magnetic field, which goes mostly
    north-south, so you can only push in the
    east-west-up-down (roughly) plane.

2.)    Gravity-gradient stabilization of the tether requires it
    to be vertical.  Since you can only push at right angles
    to the conductor, your only force is horizontal.  This
    limits you to east-west forces.

You could use a tether for lateral motion (plane changing) if you
were in a polar orbit, but then you wouldn't be able to use it
to raise or lower your orbit since the force would be at right
angles to your motion and the work done would be near zero.

>It seems possible to put a payload into a high orbit at a cheaper cost
>by launching the payload into low orbit.  If that payload carried a
>solar powered tether system (or if it could rendevous with one already
>in orbit), then the tether can be used to boost the payload the rest
>of the way for nearly free.

This only works so long as the ionospheric plasma is sufficiently
dense to carry the return current from the tether ends.  This stops
being the case above a fairly low altitude (memory does not serve
me right now, but it is below geosync).

>Mike
--
Russ Cage                  [e-mail] (until 8/28/92)
            [e-mail] (until whenever)
  *  When Ford pays me for my opinions, THEN they can call them theirs. *
                           _Bad_ cop.  No donut.

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

Date: 19 Aug 92 01:52:18 GMT
From: "Frederick A. Ringwald" <[e-mail]>
Subject: Home made rockets
Newsgroups: sci.space

In article <[e-mail]>
[e-mail] (Steve J. Quest) writes:

>         I think the point that should be made is "maybe the guy
> who wants to build engines IS more intelligent and safety
> conscious than you have given him credit for"?  All you really
> should have said was "do you know what you are doing" and if they
> respond with "I think so" then help them out.  That is my two
> cents worth..........sq

I really doubt it. First, that he even brings up the topic of a
KNO3/sugar mixture, melted and spooned into a rocket casing - just that
he can bring up this particular specification at all - shows he has no
idea just how dangerous it is, that there are much safer and more
effective ways of making rockets, and most seriously, that since he
didn't know this, he didn't do his homework FIRST before beginning work
with obviously hazardous materials. (It's a rocket, for crying out
loud!)

Second, the spelling in both his posts suggests a lack of attention to
detail that, in making homemade rockets, can lead to that nasty
surprise. He didn't even get the name "Estes" right, writing it "Stes."
The capitalization makes this an unlikely typo, too.

Along this thread, the argument "no activity is 100% safe, and the
desire for it is what's wrong with contemporary American society," has
been raised several times. It's fallacious and irrelevant. Home
explosives manufacture isn't even remotely CLOSE to 100% safe. True,
while it is possible to die from an infected paper cut from stamp
collecting, it's considerably less likely than blowing off a hand from
improperly packing a rocket casing, due to ignorance of how to do it
properly. Once body parts are blown off, they tend to stay off.

I e-mailed the original poster the list of suppliers from
rec.models.rockets, and told him I wished he could legally obtain at
least some of those products in his country, some being from Canada and
the UK. I also told him I wished he'd stick with models, until he
learned more about what he's doing, so I've had more than enough of
this thread. This is my $1.69 worth.

P.S. I have extreme difficulty believing your claim of building a
rocket with 40 kg of propellant for a few hundred dollars as a
teenager. ThatUs a veritable anti-aircraft weapon! Furthermore, I think
your assertion that it's not science unless you break the safety rules
is unconscionably irresponsible: look what happened when some real
rocket scientists broke the safety rules with Challenger.

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

Date: 19 Aug 92 13:55:37 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: Shuttle (was: Private space ventures)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] writes:

>Also in response to another post about the Shuttle and its availability, the
>routine landing of the Shuttle at KSC cancels the longer time in orbit
>for the Shuttles

I don't understand this statement. Are you saying that Shuttles can't
stay in orbit as long if they land at KSC?

>and lowers the cost per mission by 3-4 million dollars.

A reduction of about one half of one percent. Not even a drop in the
bucket.

>Also for Allan's benefit that 8 per year launch rate was achieved BEFORE
>Endeavour came on line.

Sure. It was achieved with 9 flights in 85. This rate strained the
Shuttle processing system and ended with Chalenger. Since then they
highest rate achieved was 6 per year in 90 and 91.

For 92 they scheduled nine missions, have flown 5 and will likely only
fly 7 or 8.

>A possible other use for Shuttle is to provide service to the CIS station
>as well as to SS Freedom.

Sure. Another use would be to fly it to New York and use it for low
income housing. However, I don't think that would be a cost effective
use for the Shuttle.

Is there some reason you have to think sending the Shuttle to Mir would
be cost effective?

>Don't think your Atlas/Soyuz can do that Allan.
>That is of course launching out of KSC.

But I'll bet Titan/Soyuz could. However, if I wanted to fly something
on Mir, it would be cheaper for me to charter my own private 747 and
fly it to the CIS for launch. Hell, for the cost of a Shuttle flight,
I don't need to chater the 747, I can simply BUY it and still save
millions.

   Allen

--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "If they can put a man on the Moon, why can't they     |
|  [e-mail]     |  put a man on the Moon?"                               |
+----------------------247 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: Wed, 19 Aug 1992 16:07:36 GMT
From: Jonathan Hardwick <[e-mail]>
Subject: Soyuz as ACRV
Newsgroups: sci.space

[e-mail] writes
> Also, Soyuz will need to be certified for a
> possible water landing.  We do not have areas like the steppes of Asia
> to land in like the Russians.

Uhhh, this may be stupid, but why not just land on the steppes of
Asia, or any other flat land surface that happens to be within reach
when an emergency hits?  It's not like the capsule would be reused,
nor need we worry about the Russians getting their hands on new
technology :-)  Heck, they'd probably appreciate the return of their
raw materials.

Jonathan H.

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

Date: Wed, 19 Aug 1992 16:34:11 GMT
From: Jonathan Hardwick <[e-mail]>
Subject: Soyuz as ACRV
Newsgroups: sci.space

[e-mail] (Gary Coffman) writes
> [e-mail] (Allen W. Sherzer) writes:
> >Besides, in an earlier post you stated that ALL shuttle cargo's had to be
> >certified to 10 G in the direction of motion and 6 or so transverse. Any
> >capsule can do that easy.
>
> Those are engineering *safety* margins. Operating at the outside edge
> of the engineering envelope is never good engineering practice. One
> wind gust against your parachute, and you've exceeded engineering limits.
> Not acceptable.

How closely do SMEs approach the outside edge of the engineering
envelope?  Is this good engineering practice?

> I think that if SSTO doesn't pan out, and there's a good chance
> it won't, then we should be considering Shuttle II, a low maintenance,
> low turnaround follow on vehicle to a proven system.

Here I was thinking that Shuttle I was supposed to be the
low-maintenance low-turnaround vehicle.  The space truck, right?  Any
bets that Shuttle II turns into another expensive boondoggle?

> Taking lessons
> learned, and advances in aerospace technology over the 20 years since
> Shuttle was designed, we should be able to make as large an incremental
> improvement as the step from the 707 to the 767 in the Shuttle. This
> would take advantage of existing, and *paid for*, facilities at the
> Cape and at Rockwell while cutting ground servicing personel costs
> sharply. That's what really drives Shuttle launch costs.

Uh-huh.  Wings are great for getting back down cheaply.  Wings suck
for getting up there in the first place.  Spam-in-a-can is going to be
economically justified for a long time to come, and if the US space
program sticks exclusively with winged vehicles, it's going to be
throwing money away that could be used for something else.

Jonathan H.

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

Date: 18 Aug 92 07:22 PDT
From: Mark Goodman <[e-mail]>
Subject: space industry
Newsgroups: sci.space

To:
From:  Mark Goodman ([e-mail])
Re:
Date:

[e-mail] (dann cutter) writes:

>Could anybody out there please tell me the current status of the private
>space industry world wide. What comapnies exist... what they have done...
>thanks

I can only give you a sketch of the answer, which is all I know.
The first thing that comes to mind is the private space launch
industry, which doesn't really exist.  What exist are a number
of government/corporate ventures (France/Arianespace, China/
Long March, etc.), and a number of aspiring companies in the
United States.  There are really no private space launch providers
outside the United States -- Arianespace is the closest thing.

But the space industry is much more than that.  It includes
satellite makers (a handful in the U.S., Spar in Canada, Matra/
Marconi and maybe others in Europe, Japan?, others?), companies
that provide satellite imagery (Eosat, Spotimage, Soyuzkarta),
companies that make communication satellite downlink antennas,
companies that make components for all these systems, and more.

In general, ground services are more profitable than satellites
are more profitable than launchers, and nothing else is profitable.
The space launch industry suffers from serious problems of oversupply.
I think it is also true that the more profitable sectors are more
widely spread around the world, especially at the component level.
I believe India sells some satellite components, for example.

I hope this helps.  I'm sure others will jump in if I've said
anything wrong (or right but controversial).

+-----------------------------+-----------------------------+
|       Mark W. Goodman       | What a terrible thing it is |
| [e-mail] -- econet | to lose your mind.          |
| [e-mail]  |                             |
+-----------------------------+-----------------------------+

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

Date: 19 Aug 92 13:57:09 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: space industry
Newsgroups: sci.space

In article <[e-mail]> Mark Goodman <[e-mail]> writes:

>There are really no private space launch providers
>outside the United States -- Arianespace is the closest thing.

So what are Atlas, Delta, and Titan, chopped liver?

  Allen
--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "If they can put a man on the Moon, why can't they     |
|  [e-mail]     |  put a man on the Moon?"                               |
+----------------------247 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: 19 Aug 92 14:28:19 GMT
From: [e-mail]
Subject: space industry
Newsgroups: sci.space

In <[e-mail]> Allen W. Sherzer writes:
>So what are Atlas, Delta, and Titan, chopped liver?
  Nope, one is the 4th letter of the Greek alphabet, and the other
2 are straight out of Greek mythology .. <insert deadpan expression here>
 -----------------------------------------------------------------
               ** Of course I don't speak for IBM **
Greg Nicholls ... [e-mail] or [e-mail]
                  voice/fax: [phone]

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

Date: 18 Aug 92 14:04:26 GMT
From: Dani Eder <[e-mail]>
Subject: SPS feasibility / Astrophysical Engineering
Newsgroups: sci.space

[e-mail] (Gary Coffman) writes:

>Numbers could be 2X either way. That's still a near *planetary* body
>we're talking about plating with solar cells in any case. That's so
>unreal I'm surprised *anyone* would seriously consider it.

I'm working on a book that discusses DISMANTLING planetary bodies
(and rebuilding them more to our liking, sigh - all that wasted
mass inside planets doing nothing more useful than holding
atmospheres down, sheesh what poor design).

(1) The energy required to dismantle a planet is 0.6Mgr, where
M is the mass, g is the surface gravity, and r is the radius.

(2) If we calculate the amount of solar energy falling on a
planetary body, and relate it to the disassembly energy, we can
derive a natural time constant: how long will it take to dismantle
a planet using the sunlight falling on an area the size of the
planet?

In the case of the Moon and Mercury they both come to around 300,000
years.

Of course, there is no reason you have to be limited to the
physical area of the planet.  If you surround the Moon with a
cloud of SPSs extending 20,000 km in radius with an optical density
(area fill factor) of 10%, then you have 14 times the energy, and
the disassembly time drops to 22,000 years.

If you are really in a hurry, consider the following: Long tether
based mining conveyors.  They scoop up material from the Lunar
surface and lift it to high altitudes, where it is sent off to
wherever you wanted the stuff.  The upper ends are not bound
by the surface area of the Moon, and have much greater radiating
area.  Let us say that the upper ends function as heat engines
with a rejection temperature of 1000K.  If your thermal cycles are
40% efficient, then you can genrate nearly 30 suns of power
to run the conveyors.  If the collecting area of the upper
ends of the tethers amounts to 100 times the area of the Moon,
then we have a total power available of 3000 times the solar
constant per unit area of the Moon, and the disassembly time is
on the order of 100 years (at 100% efficiency).

Methods of disassembly include:

(1) Large body impact

Messy, but quick.  Don't let the pieces re-coalesce into a body
again.

(2) Big bomb(s)

Again, messy.

(3) Spin up to orbital speed.

You collect stuff off the equator that is now orbital.

(4) Boiloff

Good for removing pesky atmospheres, takes longer to evaporate
planet.  Use lots of concentrated sunlight

(5) Mining

Mass drivers, tethers, etc.


For those who are wondering why I am considering such stuff --
Understanding how such large scale engineering might be done can
tell us what to look for around other stars in the search for
life in the Universe.

Dani

--
Dani Eder/Boeing/Advanced Civil Space/[phone](w)/232-7467(h)/
Rt.1, Box 188-2, Athens AL 35611/Member: Space Studies Institute
Physical Location: 34deg 37' N 86deg 43' W +100m alt.
***THE ABOVE IS NOT THE OPINION OF THE BOEING COMPANY OR ITS MANAGEMENT.***

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

Date: Wed, 19 Aug 92 14:49:15 BST
From: [e-mail]
Subject: superstrings & supralight (was SPS feasibility and other space development)

> P.S. There's a preprint running around by Richard Gott (that may or
may
>

> not yet have come out in Physical Review D) that actually takes

> faster-than-light travel seriously, basically as a consequence of
what

> two superstrings passing each other do to spacetime. Thorne and
others

> are trying their hardest to find what's wrong with it, as it
severely

> strains the notion of causality...
>


Now all we have to do is find a pair of superstrings. Details,
details.... :-)

PS: when it comes out I'd love the citation so I can go dig it out.
I'm sure it's well beyond my mathematical level, but I'd sure like to
take a look at it!

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

Date: 19 Aug 92 16:10:25 GMT
From: Bill Higgins-- Beam Jockey <[e-mail]>
Subject: Weekly reminder for FAQs
Newsgroups: sci.space,sci.astro,sci.space.shuttle

[Jon Leech is taking a vacation from cyberspace.  Our Special Guest
Host this week:  Usenet's favorite ukulele-playing physicist,
W. Skeffington Higgins!]

"Thankyouthankyouthankyou.  It's great to be here.  Did you hear about the guy
who build a tethered space gambling casino?  He started out on a shoestring!
And now, on with the Weekly Reminders!"

    This notice will be posted weekly in sci.space, sci.astro, and
sci.space.shuttle.

    The Frequently Asked Questions (FAQ) list for sci.space and sci.astro is
posted approximately monthly. It also covers many questions that come up on
sci.space.shuttle (for shuttle launch dates, see below).

    The FAQ is posted with a long expiration date, so a copy may be in your
news spool directory (look at old articles in sci.space). If not, here are
two ways to get a copy without waiting for the next posting:

    (1) If your machine is on the Internet, it can be obtained by anonymous
FTP from the SPACE archive at ames.arc.nasa.gov (128.102.18.3) in directory
pub/SPACE/FAQ.

    (2) Otherwise, send email to '[e-mail]'
containing the single line:

help

    The archive server will return directions on how to use it. To get an
index of files in the FAQ directory, send email containing the lines:

send space FAQ/Index
send space FAQ/faq1

    Use these files as a guide to which other files to retrieve to answer
your questions.

    Shuttle launch dates are posted by Ken Hollis periodically in
sci.space.shuttle. A copy of his manifest is now available in the Ames
archive in pub/SPACE/FAQ/manifest and may be requested from the email
archive-server with 'send space FAQ/manifest'. Please get this document
instead of posting requests for information on launches and landings.

    Do not post followups to this article; respond to the author.

    "Thanks, ya been a great audience!"

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

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

Date: 18 Aug 92 14:39:03 GMT
From: Dani Eder <[e-mail]>
Subject: What about Saturn?/Future not Past
Newsgroups: sci.space

[e-mail] writes:

[about the revival of the Saturn launch vehicle]

How about looking to the future instead of the past?

Dr. Robert Bussard is working under contract to DARPA to develop an
'electric fusion' machine.  The way it would work is to set up
a chamber bounded by current-carrying wires, such that a magnetic
field is set up that gets weaker towards the center, and strong
towards the periphery.  Into this chamber you inject electrons,
which are reflected by the magnetic fields at the edges, and thus
bounce radially from side to side.  The electrons are denser towards
the center of the chamber if they are all bouncing radially.

This setup creates a strong negative potential well in the middle,
caused by all the electrons in the central region.  Now the fun
part: drop deuterium & tritium ions into this chamber.  They are
attracted by the electron cloud, and accelerate towards the
center.  If the potential well is deep enough (tens of kilovolts),
the ions will be going fast enough at the center to fuse when they
run into each other.  The ones that miss or scatter will continue
to bounce around until they hit something.

The ones that fuse create particles with high energy - millions of
volts, which is enough to kick them entirely out of the central
region - to generating equipment outside of the chamber.  The trick
is that you use the electrons and geometry to create a trap for the
ions you want to fuse.  Electrons are much lighter than ions, and
thus are easier to control with magnetic fields - rather than
trying to contain a plasma directly with magnetic fields as the
Tokamak tries to do.

Bussard's calculations show it is possible to produce 2000 MW of
power in a 2 meter chamber.  The system weight would be on the
order of 3-4 tons.

Electric power generation is by direct climb of the charged particles
against a megavolt field set up by wires surrounding the chamber.
This produces megavolt output at some amperage with high
conversion efficiency.  The high voltage is then used to generate
thrust in this way:

You dump megavolt electron beams into a chamber (this is a souped
up TV tube, which uses 20 kilovolt electron beam to illuminate the
phosphors).  The beam energy is absorbed in a few tens of cm by
your propellant, getting it very hot, then it goes out a nozzle.

Specific implulse in the range of 2000 seconds is possible, before
the heat of the exhaust gas sets a limit.  This is somewhat better
than the NASP average specific impulse, and you don't have to
spend lots of time in the atmosphere, as NASP does, getting hot
and fighting drag.

This would make a dandy spaceplane engine.  Once in orbit, where
you have room to build a bigger magnetic nozzle (in the atmosphere
you have to stay within the aerodynamic lines for it to fly)
The specific impulse can be increased to 3000-5000 seconds.  This
is because the power can be spread over a larger area, and waste
heat melting your nozzle is the limiting factor.

This system is close to the 'Mr Fusion' we saw in 'Back to the
Future', and allows building real spacecraft, ones that don't
fall apart (stage) in flight.

Where they are is building a scaled prototype for DARPA, to
verify the calculations in the same way a wind tunnel model
is used in airplane design.  That completed, there should be
no stopping the full size machine from working.

This may seem futuristic to some, but no more so than cryogenic
rocket engines would have seemed in the 40's, and they were
actually built for the first time in the 50's.

Dani Eder


--
Dani Eder/Boeing/Advanced Civil Space/[phone](w)/232-7467(h)/
Rt.1, Box 188-2, Athens AL 35611/Member: Space Studies Institute
Physical Location: 34deg 37' N 86deg 43' W +100m alt.
***THE ABOVE IS NOT THE OPINION OF THE BOEING COMPANY OR ITS MANAGEMENT.***

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

Date: 19 Aug 92 14:39:03 GMT
From: Larry Klaes <[e-mail]>
Subject: Will LAGEOS 2 Earth satellite have a plaque too?
Newsgroups: sci.space,sci.geo.geology,sci.astro

         Will the LAGEOS 2 satellite - scheduled for launch on the
    Space Shuttle STS-52 mission - have a plaque of some kind on it
    as the craft's predecessor did in 1976?

     To explain, LAGEOS 1, launched in 1976, was designed to help
    scientists measure the movements of continental plates.  Since
    LAGEOS 1's orbit would keep it in space for eight million years
    before plunging back to Earth, Carl Sagan had a plaque designed to
    help future explorers understand the purpose of the satellite.

     Briefly, the LAGEOS 1 plaque depicted three views of Earth's
    continents:  As they were 250 million years ago when all the land
    masses were combined into one called Pangaea; as they appeared in
    1976 (launch year); and as they will probably look in 8 million A.D..
    The plaque also contained a diagram of the satellite and a simple
    picture of Earth orbiting Sol to explain the concept of one year.

         You can read more about the LAGEOS plaque in Carl Sagan's 1978
    book MURMURS OF EARTH, which also discusses the VOYAGER 1 and 2
    gold records and the PIONEER 10 and 11 plaques to extraterrestrial
    intelligences (or humanity's future space explorers).

         Your information is appreciated.

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

              "All the Universe, or nothing!" - H. G. Wells

         EJASA Editor, Astronomical Society of the Atlantic

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

End of Space Digest Volume 15 : Issue 126
------------------------------