Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/spacedig/v15_1/v15no187.txt

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Date: Sat, 12 Sep 92 05:00:50
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #187
To: Space Digest Readers
Precedence: bulk


Space Digest                Sat, 12 Sep 92       Volume 15 : Issue 187

Today's Topics:
                 20 Questions About the Delta Clipper
                           Arstrong's Boots
                   Galileo and Ulysses fact sheets
                       How to build ion engine?
         Is NASA really planning to Terraform Mars? (8 msgs)
          One Small Step for a Space Activist... Vol 3 No 9
                              Relativity
                   SSTO has been achieved (2 msgs)
                             Terraforming
                   Terraforming needs to begin now
         Weekly reminder for Frequently Asked Questions list

    Welcome to the Space Digest!!  Please send your messages to
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----------------------------------------------------------------------

Date: 11 Sep 92 14:26:08 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: 20 Questions About the Delta Clipper
Newsgroups: sci.space

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

>The DCX is a simple craft using off the shelf parts and well
>understood technology. There may be some flight regimes in which
>there is something to be learned, but I suspect there is not much
>from a science viewpoint. Unlike other vehicles built in the past,
>its design is not a research project. This is a skunkworks aviation
>project whose only goal is operational hardware.

The main thing learned from DCX will be the viability of the flip
maneuver they use on re-entry. According to the NASA assessment of
the Delta Clipper design there isn't enough in the database to tell
if it will work.

  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?"                               |
+----------------------225 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: Fri, 11 Sep 92 07:55:11 GMT
From: Glen K Moore <[e-mail]>
Subject: Arstrong's Boots
Newsgroups: sci.space

I was aked today a question by someone who hadn't even thought of all of the useful things I know about the moon. A typical non scientist! He asked me "What material was used to make Neil Armstron's boots?" He needed the answer for a lecture on ?? and was serious in his request.

I don't know where on earth to look. Does anyone out there know the answer?

[e-mail]
Science Centre
Fax: [phone]

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

Date: 11 Sep 92 11:47:47 GMT
From: Keven Weber <[e-mail]>
Subject: Galileo and Ulysses fact sheets
Newsgroups: sci.space

G'day all,

I'm after copies of the Galileo and Ulysses fact sheets.
If anyone has either of these could they send me a copy?

Cheers.


Keven.
--

-----
Email: [e-mail]

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

Date: Fri, 11 Sep 1992 08:37:29 GMT
From: Nick Szabo <[e-mail]>
Subject: How to build ion engine?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Ron Peterson) writes:
>
>Could someone please describe to me how to build a practical ion rocket?
>...platform that could lift itself in the air powered by a solar cell
>or very small battery.  I thought that perhaps a tiny ion motor
>with a solar cell painted on its exterior might be capable of
>lifting itself off the ground.


The thrust-to-weight ratios for any know ion rocket are far too
small to lift itself off the ground.  They are currently used for
stationkeeping, which requires only a very low thrust for a long
duration.  Breakthroughs in the technology would be most important
for deep space transportation, which is very limited by the low
exhaust velocity of chemical engines, and could also be useful
in circularizing satellites from GTO to Clarke orbit.




--
[e-mail]        Tuesday, November third  ##  Libertarian  $$  vote
Tuesday  ^^ Libertarian  --  change  **  choice && November 3rd @@Libertarian

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

Date: 11 Sep 92 09:16:57 GMT
From: Nick Szabo <[e-mail]>
Subject: Is NASA really planning to Terraform Mars?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Richard Nickle) writes:
>Adding water requires small robot probes to go retrieve ice
>and move it to mars.  The robots would attach themselves to the appropriate
>piece of ice, and use the ice itself as reaction mass to move them from
>wherever you got them (Saturn, the belt) to Mars, whereupon they would
>fall onto mars and release tons of water.  You just set up your ice-retriever
>robot factory someplace convenient:  Lunar orbit?

The general idea of moving ice to Mars is good, but this is really
the roundabout to go about it.  By the time we've moved the ice into
Earth orbit, then lunar orbit, then back to Mars, we will have used up
over 95% of the ice (cf. the rocket equation and 200-300 s. Isp for the
nuclear- or solar-thermal engines using water as reaction mass).
Also, we need to process the ice with robot plants before it
can be used for reaction mass, to remove the dust (which may be up to
50% of the content) and shape the ice into something dynamically
stable (my design uses a cylinder).

A better approach is to use the Jupiter-family comets.  These can
be nudged to intercept Mars with 1-2 km/s delta-v, using up less than 1/3 of
the ice mass as propellant, and delivering the other 2/3 to the surface
of Mars.  Even better, the ice can be captured into Earth and Mars
orbit and used for transportation between the two bodies instead of
launching upper stages from Earth.  Best of all, the ice can be used
to transport even more robot plants to the comets, a bootstrapping
process that can reduce the cost of deep space transportation by five
orders of magnitude in two decades.

The two big breakthroughs here are (a) the rocket engine can be very low
power, thus low mass, and (b) the ice rockets have a near zero tankage
factor, so that even if we use up 90% of the propellant the rest is payload.

Alas, access to currently known Jupiter-family comets is marginal with
chemical upper stages.  Titan IV/Centaur can deliver about 1,000 kg
to such a comet during a good launch window, but this is probably not
enough for robot plants with current technology to make ice rockets
of a sufficient size for these tasks.  Here is where the ion rocket
could come into play to open up the solar system; the nuclear-thermal rocket
a la Timberwind would have a similar effect.  It would also be a
big breakthrough if we found ice closer, in the Apollo-Amor asteroids,
Phobos, or Deimos; finding such ice is the most important task of space
exploration.  Process technology is also an important driver.


--
[e-mail]        Tuesday, November third  ##  Libertarian  $$  vote
Tuesday  ^^ Libertarian  --  change  **  choice && November 3rd @@Libertarian

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

Date: 11 Sep 92 12:02:01 GMT
From: Andreas Michael Weder <[e-mail]>
Subject: Is NASA really planning to Terraform Mars?
Newsgroups: sci.space

>It's also laughable to look at "global warming" when a single volcanic eruption
>kicks enough enough ash to DROP temperatures despite our many years of
>unregulated environmental engineering, hmm?
>

A lot of the chemical waste we pollute the lower athmosphere with needs
several years to reach the upper regions.

>We also don't have enough of a dataset on our world to show what the "real"
>temperature should be. I kid you not. Would you like to average in the ice ages
>and the time before the DinosaurKiller impacted?
>

Even if some of the results of on-going research on the topic of global warming
were wrong, would you like to bet on that? Even if all the waste we're producing
wouldn't damage the environment at all: it's toxic and we're killing life forms
by simply dumping it in the oceans or whatever. And that's a fact. If you
disagree, watch the news.

I mean: I'm not afraid that life in whole will disappear from this planet, but
I'm quite sure that, if we continue like that, man will.

>Besides, population growth is self-correcting. People who have nothing better
>to do start little piss-ant wars and end up killing themselves off.

>                 Support U.N. military force against Serbia
                               ^^^^^^^^
Definitely. (Yawn)



Andreas Weder
[e-mail]

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

Date: Fri, 11 Sep 92 15:49:50 BST
From: [e-mail]
Subject: Is NASA really planning to Terraform Mars?

> Even if you ignore all the globe-threatening issues, *population* growth,
> which you can *count on*, will still be one of our greatest challenges.

> It will keep growing until it simply *can't* and that only happens when

> world resources, particularly in food stuffs, become steadily taxed. Don't
> kid yourselves, this is *going* to happen whether you like it or agree

> with it.
>


Read some demographics books. Population has been shifting from high birth
rate/high mortality to low birth rate/low mortality for over a century.
Population growth follows and S curve because there is a social lag between
the mortality decline and the change in desired family size. The US and
Western Europe went through this shift at and before the turn of the
century. The end result was not as disastrous because they started at a
lower baseline population and the medical technology was just being
developed. Ie, the transition was spread out enough to allow social change
to more closely track the technological change. Much of the "Third World"
got modern medicine almost as a step function and also started from higher
population bases and lower education/technology bases.

Nonetheless, country by country they are going through the transition to
stability. The exception so far has been africa, which seems to have very
stable social structures making large families desirable. Not to fear. It
will change. Whether by conscious decision or by the four horsemen is their
own decision to make.

At the end of the transition, populations tend to show NEGATIVE growth
rates. Many European countries have slowly declining populations, with the
possible exception of Ireland.

The US would show negative growth already but it is hidden by the large size
of the legal and illegal immigration.

Japan is facing a massive social security crisis in the next decade because
it's population is also graying. They have a requirement for heavy
automation because they face a lack of manpower. (The USA faces a similar
crisis due to a demographic pulse caused by the post-World War II baby boom
rather than the demographic turnover.)

China is trying to weave its' way between the Scylla of population growth
and the Charybdis of an elderly, nonworking population.

Population growth at this time is (except for africa) mostly a momentum
effect that will stabilize by 2020-2050 or so. That is the good news. The
bad news is that the stable population level could be as high as 10-15
billion.

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

Date: Fri, 11 Sep 1992 15:40:51 GMT
From: Nick Haines <[e-mail]>
Subject: Is NASA really planning to Terraform Mars?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Nick Szabo) writes:

   In article <[e-mail]> [e-mail] (Richard Nickle) writes:
   >Adding water requires small robot probes to go retrieve ice
   >and move it to mars.  The robots would attach themselves to the appropriate
   >piece of ice, and use the ice itself as reaction mass to move them from
   >wherever you got them (Saturn, the belt) to Mars, whereupon they would
   >fall onto mars and release tons of water.  You just set up your ice-retriever
   >robot factory someplace convenient:  Lunar orbit?

   The general idea of moving ice to Mars is good, but this is really
   the roundabout to go about it.  By the time we've moved the ice into
   Earth orbit, then lunar orbit, then back to Mars, we will have used up
   over 95% of the ice

You're misreading the idea: set up a factory in Lunar orbit which
makes robots. Send the robots out to where the ice is. The robots take
the ice directly to Mars. Do not pass Earth, Do not collect $200. The
main purpose of the robots is to take ice to Luna, but the factory
owner is _so_ generous (?!) that some go to Mars instead.

[...]

                    Best of all, the ice can be used
   to transport even more robot plants to the comets, a bootstrapping
   process that can reduce the cost of deep space transportation by five
   orders of magnitude in two decades.

We'll see.

Nick

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

Date: Fri, 11 Sep 92 16:02:55 BST
From: [e-mail]
Subject: Is NASA really planning to Terraform Mars?

> You do not know there is no life on Mars or anywhere else other than Earth.
> I don't see the relevance of arguing over the label of 'back yard'.  I don't
> think as a society, or even a planet, we have yet learned how to manage our
> *own* planet, not even a *little*.  Because of this I don't think we are
> qualified to begin applying our ignorance to anther planet.
>


As the joke about the Lone Ranger and Tonto goes, when the Lone Ranger saw the
indian war party on the hill, he turned to Tonto and said "We're in a heap
o'trouble". To which Tonto replied: "What you mean, WE, white man?"

My response to the above, is "What you mean, WE, <insert favorite politically
incorrect phrase here>?"

It is obvious this person will not be the one doing the terraforming. Now, at the
moment this is all moot argument. But in about 50-100 years, my return question
would be different and to the point:

    "And just HOW do you propose to stop me?"

Oh, by the way .... I expect to be quite well armed....

================================================================================
Give generously to the Betty Ford Home        [e-mail]
for the Politically Correct.            Belfast, Northern Ireland
================================================================================

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

Date: Fri, 11 Sep 92 16:26:18 BST
From: [e-mail]
Subject: Is NASA really planning to Terraform Mars?

> Furthermore, the Club of Ignorance also ignores little things like A)
> Technological Innovation is not static, B) Free-market economies
stimulate the
> development of more efficient use of resources and substitutes.

>


I might add that the Club of Rome types also refuse to consider
extraterrestrial resources and energy. All of their simulations are based
on closed, technologically static systems. This makes their models a waste
of MIPS.

I really don't think the eventual use of ETM's is questionable. The only
possible argument between optimists and pessimists is whether the have a
big impact in the next couple decades or whether it is a hundred or a
thousand years in the future. Is there anyone out there dumb enough to make
a bet that there won't be significant imports to Earth from Mars by 2992?

PS: I think I'd win the bet if I lived even until 2050.

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

Date: Fri, 11 Sep 92 16:46:25 BST
From: [e-mail]
Subject: Is NASA really planning to Terraform Mars?

> Here we are, with great difficulty even getting antennas to point
in the
> correct direction and this guy suggests that we can throw jillions
> of tons of matter at a planet accurately. Yes indeed, really
refreshing.
>


A) We don't seem to have been having any trouble getting things to go
where we want them, even with multiple fly bys.

B) Who cares where the antenna is pointing as long as the water hits
the planet?

C) Who cares if a few percent miss?

D) This ain't 1992 that we are talking about The above comment is
about as relevant as making a complaint in 1492 that horseshoes can't
be made to survive a transcontinental trip across Eurasia...

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

Date: Fri, 11 Sep 92 08:55:06 PDT
From: "UTADNX::UTDSSA::GREER"@utspan.span.nasa.gov
Subject: Is NASA really planning to terraform Mars?

In Space Digest V15 #180,
Nick Szabo <[e-mail]> writes:

>In article <samw.715971213@bucket> [e-mail] (Sam Warden) writes:
>
>>The spread of terrestrial life to other now lifeless environments
>>seems _very_ moral to me, even a moral imperative, given a possibly
>>limited window of ability to do so.
>
>Even while perhaps disagreeing about the size of that window, I wholeheartedly
>agree that this is a moral imperative, not "pollution" or "ruining the planet"
>as the politically correct would have us believe.

I'm not sure if I would call it pollution, but "moral imperative"?
What kind of gods are you guys making up, anyway?

>[e-mail]  Public Access User --- Not affiliated with TECHbooks
>Public Access UNIX and Internet at [phone] (1200/2400, N81)

_____________
Dale M. Greer, whose opinions are not to be confused with those of the
Center for Space Sciences, U.T. at Dallas, UTSPAN::UTADNX::UTDSSA::GREER
                 "Pave Paradise, put up a parking lot." -- Joni Mitchell

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

Date: 11 Sep 92 14:29:02 GMT
From: "Allen W. Sherzer" <[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] (Josh 'K' Hopkins) writes:

>ESA has also done studies of an Ariane Transfer Vehicle to do logistics for
>Freedom.  It has two advantages I see over either of the above suggestions.
>First, its launched on a vehicle that, while still vaporware, is looking to be
>done one time and inexpensive to launch.  Second, if ESA does the resupply, we
>don't have to pay anything.

So we have yet another option.

I don't care which one we use so long as it is the cheapest.

  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?"                               |
+----------------------225 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: 11 Sep 92 11:39:01 GMT
From: Hartmut Frommert <[e-mail]>
Subject: Relativity
Newsgroups: sci.space

[e-mail] (Shawn McCarthy) writes:

>Ok.. you look like you know what ur talking about (considerably more than i do
>anyway.. :>  ) got a question: what if that train is moving just 5mph slower
>than c (as measured from the station) and i run forwards at 6mph? According to
>the train, i am moving at 6mph.. what does the station see? (or move a flag
>foreward at that speed on the outside, so they can see it) ... when the object
>(me or the flag) moves past c according to the station, what happens? or is that
>a case of the train being shorter (from the station) so the speed really ISN'T
>faster than c..?

given:
  station velocity relative to observer:     v_1
  your velocity relative to station:         v_2
-->
  your velocity relative to observer:
         v = (v_1 + v_2) / [1 + (v_1*v_2 / c^2)]
i.e.
  v = (c+1 mph) / (1+6 mph/c-30 (mph/c)^2) = c - 4.99999968 mph

which is clearly *slower* than c.
--
 Hartmut Frommert                 <[e-mail]>
 Dept. of Physics, Univ of Constance, P.O.Box 55 60, D-W-7750 Konstanz, Germany
                                            -- Eat whale killers, not whales --

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

Date: Fri, 11 Sep 1992 11:11:05 GMT
From: Hartmut Frommert <[e-mail]>
Subject: SSTO has been achieved
Newsgroups: sci.space

[e-mail] (Kevin W. Plaxco) writes:

>[..] a lunar SSTO was an achievable
>task in 1969.

>But what about a martian SSTO?  I have seen several discussions
>about the logistics of a manned (or even unmanned return) mars
>mission, but I have never seen a proposal for how to achieve
>mars orbit after the mission has ended.  How difficult will this be?

I have seen Mars ascent descent vehicle (ADV) plans, some of which included a
SSTO ascent stage, and some even being only 1-stage ADV, years ago. If I
remember right, Wernher von Braun described a Mars ADV with SSTO ascent stage
as early as the early 1950s; ok, that's out of date since it presumes a
Martian atmosphere of much higher density than really present and therefore
had a winged Mars lander. About 1969 there was probably also a technology for
a Mars SSTO -- if one could only get there.

As far as I noted there are both SSTO and TSTO Mars ascent stages under
consideration now.
--
 Hartmut Frommert                 <[e-mail]>
 Dept. of Physics, Univ of Constance, P.O.Box 55 60, D-W-7750 Konstanz, Germany
                                            -- Eat whale killers, not whales --

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

Date: Fri, 11 Sep 1992 13:10:26 GMT
From: Nick Szabo <[e-mail]>
Subject: SSTO has been achieved
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Kevin W. Plaxco) writes:
>As the subject line says, a Single Stage ascent To Orbit has been

>But what about a martian SSTO?  I have seen several discussions
>about the logistics of a manned (or even unmanned return) mars
>mission, but I have never seen a proposal for how to achieve
>mars orbit after the mission has ended.  How difficult will this be?

It should be quite straightforward to build an SSTO for 1/3 gravity.
We wouldn't want to do it any other way -- every tank we drop has to
come from Earth, a very expensive proposition.  Combinining a very
reusable Mars SSTO with native propellant reduces the ongoing costs of
shuttling to and from Mars orbit by several orders of magnitude,
assuming a large market.  The same craft could be used to hop all over
the planet, greatly increasing mobility and exploration.

It would help if the Earth and Mars SSTO's used the same propellant
(CH4/LOX), but even an LH/LOX SSTO shouldn't be to hard to convert
to Martian CH4/LOX, given the relaxed constraints of Mars' gravity
well.


--
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Tuesday  ^^ Libertarian  --  change  **  choice && November 3rd @@Libertarian

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

Date: Fri, 11 Sep 92 16:04:32 BST
From: [e-mail]
Subject: Terraforming

> The athmosphere, as we all now, seems to be an enourmously complicated
> system. It gets kicked out of balance due to meteor impacts, changes
> to the angle of Earth's axis and the like.

This is not relevant to Dr. Zubrin's thesis.


> So if you would be able to heat up this system in a few decades it

> probably wouldn't be stable at all. It would cool out, heat up
> again and maybe would never ever find it's balance again.
> I'm very suspicious if a "solution" to a problem like this turns out
> to be a brute-force method.
>


This was not simulation, but a simple matter of temperature and pressure
curves and the direction that things are driven. He showed that Mars is
bistable and that as time goes on, the warming up of the sun is making it
easier and easier to push it over the edge so that it will fall into the
upper bistable state. His logic and charts seemed quite solid, but as I
don't have a copy of my own to refer to, I cannot in good faith defend his
thesis much better than this. We'll just have to wait until it show up
in the literature somewhere.

Oh, and it is most decidely NOT a brute force method. It is more like
tweaking a parameter of a bistable feedback control system just enough to
make it runaway into the the second state.

And yes, if you read what I posted I noted that it would reverse if the
atmosphere becomes O2 rich.  It would become transparent and allow cooling.
But the CO2 atmosphere supports positive feedback that keeps things warm
enough to keep the CO2 gaseous.

=========================================================================
Are PC owners Internet Challenged?    Dale Amon,Queens University Belfast
                          (!!!Incoming!!!!)
=========================================================================

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

Date: 11 Sep 92 09:38:00 GMT
From: pete <[e-mail]>
Subject: Terraforming needs to begin now
Newsgroups: sci.space

In article <[e-mail]>,
[e-mail] (Jeff Jackson) writes...
>
>On the wall of a nearby office is this neat picture of a planet with
>large amounts of liquid water, but large portions of the land mass is
>brown -- dry, relatively lifeless desert.  How about some ideas on how
>to terraform good old earth?  Starting with the Sahara or Austrailia's
>outback.
>
>I guess the hard part is getting fresh water to these regions.  Here's
>my wild, uneducated, naive silly idea for all ya'll to shoot holes in.
>There's tons of sand in these deserts.  You can use sand to make
>glass, so, use all this glass to make huge solar distillation systems.
>I'm envisioning long salt-water canals running from the Med. Sea, or
>Oceans running hundreds of miles inland.  Covering each canal is a
>greenhouse that heats the water up and makes it evaporate.  At the top
>of the greenhouse, the vapor is collected and cooled of, and the resulting
>distilled water is then pumped out into irrigation canals runing
>perpendicular to the salt-water canals.
>
>Yes, I'm an idiot, but tell me why.  Why won't it work?  What *would*
>work?
>

Jeez that's bizarre. I had that exact idea some 10 years ago, in
detail. Plus a few more twists: use the glass to form solar mirrors
to fire the glass factories, and use the fresh water to grow crops
on the ground sheltered from direct sunlight beneath the evaporation
panels. The vapour is condensed by cool sea water flowing into the
system along the tops of the evaporators.
     I see 2 major problems with this scheme, besides labour:
1) glass requires lime, to lower its melting point, and yield
a strong product. Also sand must be very white to yield transparent
glass.
2) how do you pump the seawater cheaply?

===========================================================================
Hey, Sahara Sandblast Inc.,                                 Pete Vincent
yeah that's the ticket.

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

Date: 10 Sep 92 13:51:44 GMT
From: Jon Leech <[e-mail]>
Subject: Weekly reminder for Frequently Asked Questions list
Newsgroups: sci.space,sci.astro,sci.space.shuttle

    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
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    (1) If your machine is on the Internet, it can be obtained by anonymous
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    (2) Otherwise, send email to '[e-mail]'
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help

    The archive server will return directions on how to use it. To get an
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    Use these files as a guide to which other files to retrieve to answer
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------------------------------

End of Space Digest Volume 15 : Issue 187
------------------------------