Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/spacedig/v15_1/v15no194.txt

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Date: Sun, 13 Sep 92 05:02:10
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #194
To: Space Digest Readers
Precedence: bulk


Space Digest                Sun, 13 Sep 92       Volume 15 : Issue 194

Today's Topics:
                        20 questions about th
                          Asteroid explorer
                      Clinton and Space Funding
         Is NASA really planning to Terraform Mars? (3 msgs)
                             Mars Direct
           Maximum Interplanetary Launch Velocity? (2 msgs)
                               Mirrors
                     NASA working on Apollo rerun
          One Small Step for a Space Activist... Vol 3 No 9
                        Pluto Direct/ options
                   Pluto Direct Propulsion Options
               QUERY Re: Pluto Direct/ options (3 msgs)
                            RL-10 (3 msgs)
                                 SPS
                          Terraforming Mars

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Date: 13 Sep 92 01:03:34 GMT
From: tom neumann <[e-mail]>
Subject: 20 questions about th
Newsgroups: sci.space

To: [e-mail]

Hi Allen!

I seem to have missed the article about the 20 questions (and
hopefully answers! ;-) about Delta Clipper.

If you still have the article would you please Emal it over to me?

Thanks,

Tom Neumann
---
 ~ DeLuxe} 1.21 #350 ~ I'm SO confused...
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------------------------------

Date: 12 Sep 92 19:26:15 GMT
From: Steinn Sigurdsson <[e-mail]>
Subject: Asteroid explorer
Newsgroups: sci.space

I think the first post of this was nuked by capricious postware..

Given some recent discussion on NASA approaches, howabout the
following for a small explorer mission:

As per the AO you get $17million (1992) for hardware, R&D,
staff etc, same again for launch; mission ops and data analysis
are extra. So, put together a CCD camera, a (IR?) spectrometer,
a low(medium?) gain antenna, redundant tape recorders, the best CPU
and memory that's flight qualified (is the intel chip qualified yet?)
and a couple of ion thrusters with as much fuel as possible - then
go cruise asteroids, first an Earth crosser, then follow it out
to the belt and peek around, keep going till you run out of fuel
or something dies; main problem would be a power supply and weight
constraints... Nick, Phil? you wanna put your time where your mouth
is?

|  Steinn Sigurdsson    |I saw two shooting stars last night        |
|  Lick Observatory    |I wished on them but they were only satellites    |
| [e-mail] |Is it wrong to wish on space hardware?        |
| "standard disclaimer"    |I wish, I wish, I wish you'd care - B.B. 1983    |

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

Date: 12 Sep 92 23:24:02 GMT
From: Henry Spencer <[e-mail]>
Subject: Clinton and Space Funding
Newsgroups: sci.space,sci.astro

In article <[e-mail]> [e-mail] (Vignes Gerard M) writes:
>    ... we also know that Clinton and Gore are
>    hostile to technology and research spending
>    and especially to projects involving
>    space exploration and astronomy.

Of particular note is that John Pike reportedly has major input to their
space positions and is likely to be head of the Space Council staff if
C/G are elected.  He basically opposes manned spaceflight and does not
believe that cheaper launch vehicles (e.g. SSTO) are possible.  Or so I
am told; those who get to vote in this election might wish to investigate
further if you care about the future of spaceflight.

Followups redirected to talk.politics.space.
--
There is nothing wrong with making      | Henry Spencer @ U of Toronto Zoology
mistakes, but... make *new* ones. -D.Sim|  [e-mail]  utzoo!henry

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

Date: 12 Sep 92 20:39:23 GMT
From: Nick Szabo <[e-mail]>
Subject: Is NASA really planning to Terraform Mars?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Phil G. Fraering) writes:
>More to the point: you wake up forty years from now and
>overnight, without warning, someone's gone ahead and dumped
>about a megaton or so of halon into the Martian atmosphere,
>and there seem to be all these lakes and oceans forming
>all over the place.
>
>Question: who owns the land?

'Tis called property rights.  There needs to be a legal regime where the
halon investors get to auction off the land to pay for the operation.
Commerce can and does invest in 40-year projects; cf. Chevron's investment
in drilling oil and natural gas in Siberia beyond 2030.

Another question: what happens to the astronauts huddling in capsules
at the "Mars Base", when the comet chunks start hitting and the
ocean rises to ungulf their little SSF modules?

Should we warn them first?  :-)


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

Date: 12 Sep 92 20:30:36 GMT
From: Nick Szabo <[e-mail]>
Subject: Is NASA really planning to terraform Mars?
Newsgroups: sci.space

In article <[e-mail]> "UTADNX::UTDSSA::GREER"@utspan.span.nasa.gov writes:
>
>
>I'm not sure if I would call it pollution, but "moral imperative"?
>What kind of gods are you guys making up, anyway?

All of them, plus the rest of civilization.  The moral imperitive
is to spread civilization across the solar system, instead of keeping
all our eggs on one planet.


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

Date: 12 Sep 92 22:11:45 GMT
From: Steinn Sigurdsson <[e-mail]>
Subject: Is NASA really planning to Terraform Mars?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Paul Dietz) writes:

   In article <[e-mail]> [e-mail] (Josh 'K' Hopkins) writes:

   > I think my question was legitimate.  Do you believe the situation is going to
   > improve as population gets larger?  I'm not so worried about "overpopulation"
   > per se.  What I do believe is that allowing people to have control of the
   > number of children they raise will result in a lower growth rate, which I
   > believe to be an improvement.

   I see no reason why it should get worse.  To first order, and within
   limits, the population doesn't matter, because food production

Here's some data recently posted:

>From: [e-mail] (Howard Gayle)
>Newsgroups: sci.environment
>Subject: Chronic undernutrition in developing regions


>The 14 August 1992 issue of Science has (p. 876) a table from an
>FAO report of 26 July 1992.  Here's part of the table, for all
>developing regions:

>Period   Total population (10^6)    Chronically undernourished (%)
>------------------------------------------------------------------
>1969-71     2 609                   36
>1979-81     3 262                   26
>1988-90     3 938                   20

>In each region, even though the population is increased, the
>fraction of the population that was chronically undernourished
>decreased.


Interestingly here are the absolute numbers of undernourished...

1969-1971    939M
1979-1981    848M
1988-1990    788M

Absolute numbers are decreasing! This was a surprise.

|  Steinn Sigurdsson    |I saw two shooting stars last night        |
|  Lick Observatory    |I wished on them but they were only satellites    |
| [e-mail] |Is it wrong to wish on space hardware?        |
| "standard disclaimer"    |I wish, I wish, I wish you'd care - B.B. 1983    |

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

Date: 12 Sep 92 20:24:47 GMT
From: Nick Szabo <[e-mail]>
Subject: Mars Direct
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Frank Crary) writes:
>To get this figure, you altered the assumptions of Mars Direct. (E.g. not
>to do detailed safety studies on a space station, etc...) The assumption
>behind Mars Direct is to take some risks in this respect. The difference
>is $150 billion for one mission (if you carefully test everything out in
>advance) versus $50 billion for five missions (if you take a risk). While
>I agree your analysis is more like NASA's usual way of doing business,
>I think it also shows the problem with that approach.

So, you are proposing that safety studies constitute 1-1/(5*150/50),
or 93% of the cost of SSF?  That's interesting. :-)



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

Date: 12 Sep 92 21:15:40 GMT
From: Nick Szabo <[e-mail]>
Subject: Maximum Interplanetary Launch Velocity?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Andrew - Palfreyman) writes:
>Relative to the Earth, what is the highest velocity we
>can currently boost to for interplanetary missions?

Titan IV/Centaur can do about 10 km/s for a small payload before
it craps out.  With a good electric plasma rocket (eg the famous
Russian Hall-effect rocket to be used for comsat upper stages)
we could get that beyond 20 km/s, which is enough to get to and return
from Jupiter-family comets, the asteroid belt, Jupiter, etc. on direct
trajectory.  Due to the incredibly bad allocation of NASA funds in
the current political climate, JPL doesn't have enough resources to
turn the Russian engine into an operational deep-space stage.

>Would a gravity assist from the Moon make much differenc
>even if repeated?

The Moon can give up to  a 1.5 km/s boost on both outbound and inbound
trajectories, but the windows are so rare that this is typically not
considered as an option.  A variant of this was used to get ICE from
its LaGrange point to a comet flyby back in the mid-80's.


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

Date: 12 Sep 92 23:03:49 GMT
From: Henry Spencer <[e-mail]>
Subject: Maximum Interplanetary Launch Velocity?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Andrew - Palfreyman) writes:
>Would a gravity assist from the Moon make much difference,
>even if repeated?

After you reach escape velocity, you don't get to repeat it any further!
Lunar gravity assists are mildly useful, but the win isn't big enough to
be worth the narrow launch windows unless you've got a mission that can't
quite be flown otherwise.  The Moon is too small to give good gravity
assists.  The only interplanetary mission that has used lunar gravity
assist, as far as I know, is ICE, and that was a spacecraft that was
meant for near-Earth operations and didn't have the fuel to get into
an interplanetary trajectory otherwise.
--
There is nothing wrong with making      | Henry Spencer @ U of Toronto Zoology
mistakes, but... make *new* ones. -D.Sim|  [e-mail]  utzoo!henry

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

Date: Sat, 12 Sep 1992 22:33:45 GMT
From: Henry Spencer <[e-mail]>
Subject: Mirrors
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (John Roberts) writes:
>How come those solar sails zoom across space while carrying a payload, then
>when you get to Mars and remove the payload (thus making them even less
>massive), they just sit there? :-)

Park them in a position and at an angle where the combined effects of
Martian and Solar gravity balance the photon thrust.  Such positions do
exist; Robert Forward has patented the idea of using them for high-latitude
"geostationary" comsats.  The question for this application is, can you
find such positions where the reflected sunlight hits the planet?  (Bonus
for having it hit the polar caps in particular.)

An alternative is a dynamic system where the sails spend some of their
time as reflectors, acquiring velocity in some undesired direction, and
the rest of their time as sails, maneuvering back.  The question here is,
what's the best duty cycle you can achieve?

Frankly, if you want to warm up the planet, the idea of adding halocarbon
greenhouse gases to its atmosphere strikes me as superior.  The ratio of
results to effort seems much better.
--
There is nothing wrong with making      | Henry Spencer @ U of Toronto Zoology
mistakes, but... make *new* ones. -D.Sim|  [e-mail]  utzoo!henry

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

Date: 12 Sep 92 23:28:24 GMT
From: Josh 'K' Hopkins <[e-mail]>
Subject: NASA working on Apollo rerun
Newsgroups: sci.space

[e-mail] (Nick Szabo) writes:

A fairly legitimate attack on NASA's return to the moon program.

>Those expecting a lunar base out of NASA's proposed "return to the
>moon" are in for a big disappointment, according to a recent Aviation
>Week article.  It describes FLO, which stands for "First Lunar
>Operations", apparently because it repeats in form and function
>our first lunar operations, Apollo.

[stuff deleted]

Included in a list of criticisms was:

>  The space suits would be designed
>from scratch instead of using those from Apollo or STS.

Nick, talk to _anyone_ who know's what they're talking about and you'll see
that new suits are high on the list of required technology for the Moon.
Both the astronauts and the suits suffered significant wear and tear on the
Moon.  They (both the suits and the wearers) just plain wouldn't last 45 days.
--
Josh Hopkins        "I believe that there are moments in history when challenges
                     occur of such a compelling nature that to miss them is to
[e-mail]   miss the whole meaning of an epoch.  Space is such a
                     challenge"       - James A. Michener

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

Date: 12 Sep 92 20:09:34 GMT
From: Nick Szabo <[e-mail]>
Subject: One Small Step for a Space Activist... Vol 3 No 9
Newsgroups: talk.politics.space,sci.space

In article <[e-mail]> [e-mail] (Allen W. Sherzer) writes:
>
>With the support NASA, the
>contractors, and Congress is giving it IS going to get built.
>The Senate vote last Tuesday just confirms it.

Next year Congress will likely have 150 new members, elected to cut the
budget (that's what all the pols out here are running on). We will have
a new President, and Al Gore in charge of the Space Council.  They will be
looking for something visible, and symbolic of the Reagan/Bush years,
to cut. Do you seriously think Al Gore is going to promote Reagan's SSF at
the expense of EOS and his fiber optic network?

Note that even this year, SSF's budget request of $2.3 billion was cut
to $1.9 billion.

>>The probability of SSF being a significant milestone in space
>>development remains very low;
>
>Sure. But that's not the point. We are now past trying to kill it and
>must now find ways to live with it.

How about just ignoring it?

>We aren't talking about a unique capability. What we are talking about
>is a market driven solution to reduce costs.

For the Nth time, NASA is not a commercial market!  It is a government
agency, funded from year to year, that dictates design details to its
contractees, and funds the projects via the process of political
lobbying.  If you could come up with a viable scenario where the main
customers are, say, direct broadcast satellites, and NASA funds the
first couple launches of an HLV for those customers while keeping
hands off the design, I would believe the rhetoric about market-driven.
However, if Ariane 5 meets its cost targets it will be a great HLV
for launching the larger DBS's.   I don't see any NASA-driven launcher
being competitive with Ariane 5, now that they've dumped Hermes and
are getting serious about cutting costs (their target is to reduce
the cost of the 4, already the lowest-cost launcher in the world, in
half).

>>[160,000 lbs.]

>That is the estimates I have for the amount of material which will
>be lifted to Freedom every year.

That's somebody's wet dream, is what it is.  NASA doesn't have that
kind of money for SSF, nor should it be handed a justification for it.
Furthermore, as Mike Kent noted it makes more sense to launch it in
20,000 lb. chunks, which can easily be handled by current commercial
launchers.

>>This service has a politically risky future,
>>both in terms of funding SSF and non-use of the Shuttle.
>
>We can wait for Freedom (should the market require that andlthough since
>we are talking about doubling the market it's worth a lot of risk). But
>you are correct in that it will require NASA to say up front that they
>will be open minded about it.

No, it requires a _commitment_ with money up front.  NASA is
funded year to year and ya can't sue the government -- look at what
happened to Spacehab and SSI.  Nobody does business with Uncle Sam
based on a promise of being "open minded" on the issue of payment.

>>MM already charges $280 million for Titan IV; how are they
>>going to launch more than twice the payload with the same
>>tech for less than $200 million?
>
>First of all, they charge less than that for Titan IV (the figure I
>have seen is $225 million. In addition, the Titan V doesn't use the
>Centaur upper stage (which is included in the $225 million).

The most recent figure I've seen, on an article about the Pluto probes,
is $400 million for one Titan IV/Centaur launch.  That's government
accountants for ya.  (That's also what happens when the Uncle Sam,
in this case the USAF, promises a big set of orders and then reneges on
it).

>>It makes more sense to use the Shuttle phase-out to fund
>>new technology, like AMROC and SSTO,
>
>I myself would rather just have the government buy services and
>let the market fund vehicle development.

I sympathize with this, but there is room for NASA R&D as long at it is
done in service of the space industry, instead of for its own narrow
purposes.  (Imagine that, me more socialist than Allen :-)  NASA's
aeronautics side would be a good model to follow; they develop basic,
widely applicable tech instead of building 700-person mega-SSTs that
nobody but themselves would use.

>I have shown that for the cost of Shuttle they can easially fund
>the vehicles I speak of with private money. If Martin selects Titan V
>or Titan IV for their bid is up to them. I only use the Titan V because
>it is cheaper.

I have no major quarrel with this, as long as Titan V is also cheaper
for commerce and military.  Ariane 5 will likely be fine, but their's
nothing like competition to keep them on their toes.



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

Date: 12 Sep 92 18:48:48 GMT
From: Steve Willner <[e-mail]>
Subject: Pluto Direct/ options
Newsgroups: sci.space,alt.sci.planetary

From article <[e-mail]>, by [e-mail]
(Henry Spencer):
> Of course, as it turned out, Titan was a disappointment... but there was
> no way to be sure of that in advance.

A matter of taste, I suppose.  There were no pretty pictures, but the
atmospheric composition, pressure, and temperature structure were
fascinating.  I'll take "disappointments" like that any day.
--
Steve Willner            Phone [phone]         Bitnet:   willner@cfa
Cambridge, MA 02138 USA                 Internet: [e-mail]
  member, League for Programming Freedom; contact [e-mail]

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

Date: 12 Sep 92 23:20:25 GMT
From: Henry Spencer <[e-mail]>
Subject: Pluto Direct Propulsion Options
Newsgroups: sci.space

In article <[e-mail]> [e-mail] ("Phil G. Fraering") writes:
>>... is there a way to convince them to use post-early-
>>1960's technology, like an ion drive of some sort?
>
>\Not until somebody space-qualifies modern hardware of that sort...
>
>But they apparently intend to use very new modern hardware for
>the sensors. Why is this not "risky" but propulsion is?

Would you believe "because"? :-)

I haven't seen specs for the sensors proposed, but I'd bet they aren't
too far from things already flying.  This is an area where there has been
active development, only somewhat retarded by spacecraft planners'
conservative impulses.  (You realize, I trust, that the only reason
Galileo uses solid-stage imaging sensors is that JPL's favorite imaging
tubes had gone out of production?)  Something like ion propulsion would
be a radical change from existing space systems.

>[power-source problem]
>Use solar. I'm currently thinking along the lines of a Pluto flyby,
>but with ion drives instead of solid rockets for the final kick...

Remember that you don't get a "kick" from ion rockets. :-)  Any mission
using them gets to spend months or years accelerating, and has to have
power until the end of that phase.  Given a desire to fly to Pluto in
under a decade, the sunlight's going to be getting pretty dim by the end
of the acceleration phase.

>Using advanced propulsion, instead of just another set of solid
>rockets, would, if it turned out to be a mistake, at least be
>a _new_ mistake.

Amen.  But NASA isn't allowed to make mistakes any more.  Of course,
they still do... but *deliberately* doing something risky and having
it fail is much worse (politically) than having a conservative mission
fail in some unexpected way.  At least, that's the perception.

This is, of course, a recipe for bringing progress nearly to a halt.
To make progress, you have to accept risks.
--
There is nothing wrong with making      | Henry Spencer @ U of Toronto Zoology
mistakes, but... make *new* ones. -D.Sim|  [e-mail]  utzoo!henry

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

Date: 12 Sep 92 23:10:55 GMT
From: Henry Spencer <[e-mail]>
Subject: QUERY Re: Pluto Direct/ options
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Mario Wolczko) writes:
>Given that there are two bodies (Pluto and Charon), would it be
>possible to lose enough energy by sling-shotting around them
>repeatedly...  Or are they too small to have enough of a
>gravitational effect?

They're basically too small.  You really have to get into some kind of
orbit around them on the first pass; otherwise you end up in a solar orbit
(at best; at worst, you're beyond solar escape velocity) that will bring
you back to Pluto's orbit decades -- more likely centuries -- later.
They are small bodies and orbital velocity around them will be low, so
you have to kill essentially all your interplanetary velocity.  This just
isn't feasible with such weak gravitational fields to work with.
--
There is nothing wrong with making      | Henry Spencer @ U of Toronto Zoology
mistakes, but... make *new* ones. -D.Sim|  [e-mail]  utzoo!henry

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

Date: 12 Sep 92 20:01:22 GMT
From: [e-mail]
Subject: QUERY Re: Pluto Direct/ options
Newsgroups: sci.space

Ron Baalke writes:

> Pluto does have a
> tentative atmosphere, but we know so little about it.  A flyby mission will
> help to enlighten us.

I think you meant "tenuous", not "tentative".  The detection of the atmosphere
via the stellar occultation method was quite certain.  The surface pressure
is approximately 1 microbar, however, so aerobraking isn't very practical,
unless we plan to fly a feather to Pluto.

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

Date: 12 Sep 92 20:07:51 GMT
From: [e-mail]
Subject: QUERY Re: Pluto Direct/ options
Newsgroups: sci.space

Nick Janow writes:

> Would it be possible to aerobrake at Uranus or Neptune, perhaps also using the
> atmosphere to change trajectory significantly?  This would provide a fast
> flight for much of the journey and have the remaining part at a speed slow
> enough for aerobraking in Pluto's atmosphere, or at least a much slower pass
> by Pluto.  It would also allow a mission at Uranus or Neptune.
>
> I can see lots of problems with this, but sometimes wild ideas are workable.

One big problem is that Pluto isn't lined up with either Uranus or Neptune.
It would take less time to fly direct to Pluto than to wait for the next
orbital alignment that would permit a Uranus or Neptune flyby (well in excess
of a hundred years).  You don't save much by going to Neptune first now.
The current Pluto-Neptune elongation is about 50 degrees.  If it were 60
degrees, we'd have something close to an equilateral triangle, which means
Pluto would be just about as far from Neptune as it is from Earth!

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

Date: 12 Sep 92 22:45:51 GMT
From: Henry Spencer <[e-mail]>
Subject: RL-10
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Allen W. Sherzer) writes:
>>RL-10 failures? What does that do to Allen's statistics for the reliability
>>of the engine to be used for DCX?
>
>Even with the failures it's still extreemly reliable. However, it is not
>a problem because in both cases the problem was that the engine failed
>to fire, not go boom. So all DCX need is enough engines for an engine
>out capability (which it has).

Another side of this, too, is that all engines on Delta Clipper are firing
at launch... so an ignition failure can probably be a pad abort rather than
an engine-out flight or a mission failure.  This is one place where
multistage vehicles lose badly.
--
There is nothing wrong with making      | Henry Spencer @ U of Toronto Zoology
mistakes, but... make *new* ones. -D.Sim|  [e-mail]  utzoo!henry

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

Date: 12 Sep 92 22:41:31 GMT
From: Henry Spencer <[e-mail]>
Subject: RL-10
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Phil G. Fraering) writes:
>>RL-10 failures? What does that do to Allen's statistics for the reliability
>>of the engine to be used for DCX?
>
>They may be _electronics_ failures of some sort. I don't think
>we've gotten enough parts back to find out for sure.
>
>If they ever actually used the shuttle for retrieval like all
>the people here talk about how they need to spend 5 billion a
>year to the end of time on the shuttle for payload retrieval,
>we'd know what the problem was.

The shuttle is not good at retrieving things from the bottom of the ocean,
unfortunately, which is where those Centaurs ended up...

The first one was thought to be ice, or something, in the turbopumps
interfering with startup.  I haven't heard any verdict yet on the second
one; I know they were taking pretty stringent precautions against pump
contamination in the wake of the first one.
--
There is nothing wrong with making      | Henry Spencer @ U of Toronto Zoology
mistakes, but... make *new* ones. -D.Sim|  [e-mail]  utzoo!henry

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

Date: 12 Sep 92 23:54:15 GMT
From: Charles Pooley <[e-mail]>
Subject: RL-10
Newsgroups: sci.space

From the AWST, Sep 7, pg 38, the recent failure was also an ignition-
but-no-thrust problem.  The engine was started twice, but the turbine
did not turn, and both engines shut down for another try.  After m2nd
shutdown range safety sent destruct command.

The RL-10 has been a real slick, reliable design, but there is a danger
of turbine sticking, and failing to start with the admission of cold H2
gas which evaporated from the initial admission of liquid H2 to the engine.
Very cold.  When running, the turbine inlet temp is low--something like
-100 F.     Because of two recent failures after so many faultless starts,
the problem is possibly related to some change in handling/checkout or
something.  Remember Apollo 13?
--
Charles Pooley                  [e-mail]    GEnie  c.pooley
EE consultant, Los Angeles, CA

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

Date: 12 Sep 92 22:38:30 GMT
From: Henry Spencer <[e-mail]>
Subject: SPS
Newsgroups: sci.space

In article <[e-mail]> [e-mail] writes:
>> Actually, you don't have to fool around with aluminum-oxygen (which
>is
>> a hassle as a rocket fuel, because both the aluminum and the
>aluminum
>> oxide are solids, where you'd really like liquid and gas
>respectively).
>
>The fuel consists of, roughly speaking, tightly wrapped aluminum
>foil. The oxidizer is water that is introduced to a lithium igniter...

For launching from the lunar surface, though, this is not what we want.
The aluminum-water rocket needs *hydrogen*, which is scarce on the Moon.
The whole attraction of the aluminum-oxygen rocket is that it uses only
elements which we know are abundant on the lunar surface.  (The existence
of frozen volatiles at the poles is uncertain and controversial.)  If we
have hydrogen, an LH2-LOX rocket works fine.
--
There is nothing wrong with making      | Henry Spencer @ U of Toronto Zoology
mistakes, but... make *new* ones. -D.Sim|  [e-mail]  utzoo!henry

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

Date: 12 Sep 92 22:57:40 GMT
From: Henry Spencer <[e-mail]>
Subject: Terraforming Mars
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (brad thornborrow) writes:
>Mars' gravity was not strong enough to keep oxygen molecules from escaping
>into space over time.  So, even if one could start plant-life on Mars,
>you'd have to have a heck of a lot of it to keep the oxygen from just
>"floating away"!!!

The key words here are "over time".  You can give Mars an atmosphere that
will last many times the total length of human history.  That's plenty;
by the time it starts to thin out sufficiently to cause trouble, we'll
be able to replace it, if it's worth the trouble.
--
There is nothing wrong with making      | Henry Spencer @ U of Toronto Zoology
mistakes, but... make *new* ones. -D.Sim|  [e-mail]  utzoo!henry

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End of Space Digest Volume 15 : Issue 194
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