Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/spacedig/v15_1/v15no181.txt

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Date: Thu, 10 Sep 92 05:06:08
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #181
To: Space Digest Readers
Precedence: bulk


Space Digest                Thu, 10 Sep 92       Volume 15 : Issue 181

Today's Topics:
             Climate cycles from Earth's orbital geometry
         Is NASA really planning to Terraform Mars? (4 msgs)
                          Landsat Pictures?
                   LDO shuttle and pilot readiness
                      Magellan Update - 09/09/92
                  mission badges for Apollo and STS
          One Small Step for a Space Activist... Vol 3 No 9
                    Pluto Direct/ options (4 msgs)
                              Relativity
              Single Stage to Orbit - How does it work?
                                 SPS
                   Terraforming needs to begin now
                        use of external tanks

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

Date: Wed, 9 Sep 92 20:13:14 GMT
From: Joe Cain <[e-mail]>
Subject: Climate cycles from Earth's orbital geometry
Newsgroups: sci.space,sci.astro,sci.geo.geology,sci.geo.meteorology

    Thanks to the people who answered the question in regard to
references. The ones that give a good toehold are:

Fisher A. G. and D. J. Bottjer, Orbital forcing and sedimentary
sequences, J. of Sedimentary Petrology, Vol. 61, No. 7, December,
1991. This whole issue is devoted to the subject of "orbital
cyclostratigraphy."

Imbrie, J. and K. Imbrie, Ice Ages: solving the mystery, Short Hills
NJ, Harvard U. Press, 1976.

and such classic articles as:

Hays, J. D., J. Imbrie, and N. J. Shackelton, Variations in the
Earth's orbit: pacemaker of the ice ages, Science, V. 194, p
1121-1132, 1976.

I noted a number of other tomes in this area, one interesting one was
written by the cosmologist who originated the continuous creation
theory (not creationist!), Fred Hoyle!

    The one item that did not emerge was a lower level article. I
did hear someone remembering that there was a TV science program of
some sort that discussed Quaternary climate changes in some detail,
but no specific reference.

Joseph Cain        [e-mail]
[e-mail]        scri::cain

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

Date: Wed, 9 Sep 1992 21:13:07 GMT
From: David Knapp <[e-mail]>
Subject: Is NASA really planning to Terraform Mars?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Richard Nickle) writes:
>In article <jvrnh5#[e-mail]> [e-mail] (Thomas H. Kunich) writes:
>>Without references it is difficult to remember, but isn't there
>>water, water vapor and possible liquid water along the interface of
>>the Martian north pole?
>>
>>If so, shouldn't this represent a possible seeding area for life forms?
>>
>>I also seem to remember that the upper atmosphere of Venus was
>>mostly water vapor even though the bulk of the atmosphere was
>>sulphuric acid.
>>
>>Perhaps I didn't make myself clear enough. I don't believe that
>>Venus could ever be made earthlike. I see the chance, however,
>>of seeding life there and letting it make it's own way.
>>
>>The same with Mars. All of the grandiose plans aside I can't see
>>the bulk of the necessary machinery being transported to Mars to
>>terraform it and then the project continued for thousands of years.
>I never understood this machinery bit though...my understanding of
>Martian terraforming was that the timescale would be large, but the
>steps taken would be rather simplistic:  slamming large ice blocks
                      ^^^^^^^^^^^^^^^^^^
>from the belt or Saturn's rings (though why anybody would want to
>throw away all that nice water, I don't know...maybe they could just
>send the low-grade ore towards mars), using orbiting mirrors to melt
>the poles, or covering the poles with dark matter to assist in raising
>the surface temperature.

I think you and I have different ideas of what is 'simplistic'

>  Once you begin to raise atmospheric pressure
>and water vapor content, you can begin seeding microbes....
>
>But all of these steps, no matter how gartantuan the time scale, are
>pretty passive.

How are you calling going to Saturn and bringing back chunks of ring big
enough to supply an atmosphere *passive*?

> You just build the stuff and leave it operating autonomously,
>and fiddle with it every decade or so.  No massive focus of manpower,
>just one hell of a long view would be necessary.

Do you understand how many 'mirrors' would be required to raise the polar
caps one degree centigrade?



--
David Knapp                                      University of Colorado, Boulder
Perpetual Student                                   [e-mail]

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

Date: 9 Sep 92 19:26:43 GMT
From: Gary Coffman <ke4zv!gary>
Subject: Is NASA really planning to Terraform Mars?
Newsgroups: sci.space

In article <samw.715971213@bucket> [e-mail] (Sam Warden) writes:
>Were Venus ever to cool off, I would expect ferocious amounts of
>oxidation/carbonation weathering to occur, for example.

Remember that chemical reactions like oxidation proceed at a rate
proportional to temperature. For most reactions, the rate doubles
for every 10 degree temperature rise. On hot Venus, the reactions
*are* going on at a furious rate. If it cooled the reactions would
slow dramatically.

The Venusian atmosphere is apparently mostly CO2 and H2SO4 now. Way
too much oxygen, carbon, and sulfur, not enough nitrogen or hydrogen.
The hydrogen is the critical part since you want to lock most of the
oxygen up as water to reduce atmospheric pressure and establish a
hydrological temperature control. Most of the primeval hydrogen
has been driven off into space by the hot atmosphere pushing the
light molecules to escape velocity.

The problem of terraforming the atmosphere requires separating out
the sulfur, reducing the CO2, and combining the resulting free oxygen
with the non-existant hydrogen. And even if you could do that, you
still have a 100 times too much atmosphere. The surface chemistry must
be a hell of battery acid and acidic complexes. Nearly every member of
the metal group is bound to be fully oxidized. Venus is a natural
toxic waste dump.

Gary
Gary

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

Date: 9 Sep 92 22:08:51 GMT
From: "Thomas H. Kunich" <[e-mail]>
Subject: Is NASA really planning to Terraform Mars?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Nick Szabo) writes:
>
>>Of course it would be unethical to interfere with any life
>>there may be already there.
>
>"Of course?"  Has our civilization changed so much that this notion
>is not only accepted, it is taken for granted?

NASA has taken very great pains to exclude any contamination
another planet with earth biology. Whether it is just because it
might screw up the tests or because of the ethics of the
matter I don't know.

But I think that, yes, we have progressed at least that much.

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

Date: 9 Sep 92 21:28:10 GMT
From: David Knapp <[e-mail]>
Subject: Is NASA really planning to Terraform Mars?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Nick Szabo) writes:
>In article <samw.715971213@bucket> [e-mail] (Sam Warden) writes:
>
>>As for the morality of this sort of thing, I don't share the
>>comfortable expectation that we as a civilization _have_
>>future centuries at our disposal for a conservative planetary
>>exploration.  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.  My opinion; others of course are free to differ.  ;-)
>
>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'd appreciate if you would not lump me into a PC pigeon hole because I
prefer to maintain my life support system.  If we are to travel to and
colonize the terrestrial planets and moons, we should do it without our
thumbs up our collective ass which is how we've approached global terrestrial
issues.  I do not trust well-meaning armchair scientists endorsing orbiting
space mirrors to solve chemical imbalances in our upper atmosphere caused
by industrial overzealousness. I see that all too often though.

If you want to make your backyard unlivable, go ahead, but the second you are
doing things that make *everyone's* backyard unlivable, you should expect
a response. If you think that this behavior is limited to vogue PC yuppies,
you are quite mistaken.



--
David Knapp                                      University of Colorado, Boulder
Perpetual Student                                   [e-mail]

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

Date: 9 Sep 92 19:37:20 GMT
From: John McDonald <[e-mail]>
Subject: Landsat Pictures?
Newsgroups: sci.space,sci.astro,sci.geo.geology

Years ago, i had information on obtaining Landsat photos based
on long-lat information.  I seem to recall the address being in
Colorado somewhere...

Could anyone send me information on getting Landsat photos
nowadays?

Please e-mail...
Thanks!

Johnny.

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M<G1I<W1S(%!R;W9O:V4@06QI96YS"E]?+5]?+5]?+5]?+5]?+5]?+5]?+5]?
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2(" @("!A<W1R;W!H>7-I8W,*

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

Date: 9 Sep 92 21:45:19 GMT
From: Henry Spencer <[e-mail]>
Subject: LDO shuttle and pilot readiness
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Gary Coffman) writes:
>... Though they undoubtedly use
>the Mark I eyeball out the window during landing, Shuttle pilots
>are supposed to be landing IFR *today*. Thus the ground simulator's
>movies aren't strictly necessary.

They are considered valuable, though, to the point where the pilots
have experimented with taking along videotapes of training-aircraft
landings, to be screened using the little monitors on the video cameras!

>... It may be that Shuttle pilots *can't*
>function sufficiently well to land the Shuttle manually after two
>months on orbit. In that case, Autoland is being developed to handle
>the problem.

Well, "developed" is a bit inaccurate.  The shuttle has theoretically
had full autoland capability from day one.  In principle, the only
things that require manual action are deploying the pitot probes and
lowering the landing gear, both of which are manual-only because they
are irreversible and could be fatal if done too early.  What is being
worked on now is not development of autoland, but convincing the crews
to actually *test* it.  All shuttle landings to date have been manual.
--
There is nothing wrong with making      | Henry Spencer @ U of Toronto Zoology
mistakes, but... make *new* ones. -D.Sim|  [e-mail]  utzoo!henry

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

Date: Thu, 10 Sep 1992 02:45:59 GMT
From: Ron Baalke <[e-mail]>
Subject: Magellan Update - 09/09/92
Newsgroups: sci.space,sci.astro

Forwarded from:
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE [phone]

                     MAGELLAN STATUS REPORT
                        September 9, 1992

     Magellan continued successful radar mapping of the surface
of Venus this week. The goal of the current mapping period is to
fill the largest remaining gap in the map of Venus which will
bring total coverage to 99 percent. The spacecraft had mapped
97.5 percent of the planet with its imaging radar during its
first two 243-day cycles.

     Controllers are planning an orbit trim maneuver next Monday,
September 14, to lower periapsis from its current altitude of 261
kilometers (162 miles) to 182 kilometers (113 miles) for the
gravity mapping cycle beginning the next day.
                              _____
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Anything is impossible if
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | you don't attempt it.
|_____|/  |_|/       |_____|/                     |

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

Date: Wed, 09 Sep 92 21:37:16 GMT
From: George Hastings <[e-mail]>
Subject: mission badges for Apollo and STS
Newsgroups: sci.space,sci.space.shuttle

Try writing to:
     Space Patch Collector's Club
     P.O.Box 17310
     Pittsburg, PA 15235-0310
--

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

Date: 9 Sep 92 19:31:28 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

           One Small Step for a Space Activist...
                             By
                  Allen Sherzer & Tim Kyger

There is an old saying in Mexico: What cannot be remedied
must be endured. With the July House appropriations vote and
with the retirement of Rep. Traxler (D-MI) it looks like Space
Station Freedom is out of remedy mode and into endure mode.
With all its flaws and costs it looks like Freedom WILL be
built (in some form anyway). At the same time, Freedom's huge
costs will consume the funds needed to go back to the Moon
and on to Mars. How can we endure this?

On the plus side, station supply will mean placing a lot of
mass into LEO, and this could make the market for launch
services a LOT bigger, which could help reduce launch
costs. But the way things currently are, NASA intends to use
only the Shuttle (with its high cost) for resupply. Not only
will this deny the advantages of a larger market but it will
add huge costs to the Station life cycle.

If a way to resupply Freedom could be found which didn't
require Shuttle, the payback would be enormous. Not only
would the larger launch markets lower costs, but non-Shuttle
based resupply could mean that the entire Shuttle program
can be phased out, freeing up roughly three BILLION every year.

So what do we need to do? We need to: 1)Fly about 160,000
pounds of supplies and experiments up and about 50,000
pounds back down (returned cargo will need low-G return);
2)Fly four crew to and from Freedom four times a year; and
3)An Orbital Transfer Vehicle needed to transport payloads
to Freedom (this is needed since we are eliminating
Shuttle).

A heavy lift vehicle would be one way to meet requirement one.
such an HLV would lift 100,000 pounds to Freedom orbit and would
carry a reusable logistics module. The logistics module would
have an aerodynamic shape (perhaps like DC-Y or an Apollo
capsule) and be capable of returning 20,000 pounds to Earth.

Such an HLV should be a commercial procurement where the
government buys launch services only (as required by current
federal law). Two candidates are Heavy Lift Delta (see One
Small Step... Vol. 2 No 2) and Titan V (see One Small
Step... Vol. 2 No 3). Both manufacturers have already offered
to sell launch services for either vehicle for less than $200
million per launch (including development costs).

The reusable Logistics Module is harder to cost out since it
doesn't exist yet. However similar efforts have costed out
around $3 billion for development; we'll toss in an extra
$100M per flight for recurring costs. At four flights per
year and amortizing development over ten years we get a cost
of about $200M per flight (including interest).

Meeting requirement 2 is easy: we can use a Russian Soyuz-TM
launched on an Atlas or Titan vehicle. All the components
exist today and have been used extensively. The only thing
which hasn't been done is integration of Soyuz on a US
launcher but since launcher/payload interfaces haven't been
standardized this should pose no serious problems. In
quantity, Atlas launches can be had for about $60 million
plus 20 million each for Soyuz. Observant readers will also
note that this eliminates the ACRV problem.

Finally, we need an Orbital Transfer Vehicle (OTV) to move
payloads to Freedom. This capability is not strictly needed
and will be rarely used but will allow us to phase out
Shuttle. This vehicle has already been costed at $3 billion
to develop.

This gives us the following costs for each year:

1. Atlas Soyuz launches (8 @ 80M each): $640M

2. Logistics modules (4 @ 200M each)  :  $800M

3. Heavy Lift Vehicles (4 @ 200M each)  :  $800M

4. Orbital Transfer Vehicle (1 @ 300M)  :  $300M

All this adds up to $2,540 million per year, which is about
half the cost of maintaining Shuttle. Using this approach would
therefore save us all about $2,500 million per year. In addition,
since it uses multiple launch vehicles with backups for every
launcher, it could be even more reliable than Shuttle.

So where does the money to develop all this come from? The answer
lies with the public sector. Many of the components needed are
available today. Contractors have already offered to build the HLVs
themselves if the government will agree to buy them. All we need do
is allow Freedom to provide the market and they will come.

                     Legislative Roundup

                            SSTO/SSRT
Sources say that Senator Pete Domenenici (R-NM) has recently
been briefed on SSRT and emerged an enthusiastic supporter.
The Senator is on the Appropriations Committee and is the
ranking Republican on the Budget Committee. He could be a
powerful ally.

The next vote is the Senate Appropriations Committee's Defense
Subcommittee currently expected for September 14. We need to get
letters to every Senator before then.

                      Commercial Space
The full House has voted on and passed the Omnibus Commercial Space
Act. However action by the Senate is looking less and less likely.

                       NSS Petition Drive
NSS has endorsed Dr. Zubrin's petition calling on the next president
to devote serious effort to SEI. Watch this space for progress reports.

--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "If they can put a man on the Moon, why can't they     |
|  [e-mail]     |  put a man on the Moon?"                               |
+----------------------227 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: Wed, 9 Sep 1992 18:57:00 GMT
From: "Horowitz, Irwin Kenneth" <[e-mail]>
Subject: Pluto Direct/ options
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (robert.f.casey) writes...
>If we send 2 probes to Pluto, maybe we should design them so that they
>can "talk" to each other.  In case one has a stuck antenna, like one
>we have en route to Jupiter.  Then one can relay data from the other.
>Or a dead high power transmitter, or a deaf receiver, and such.
>
>I suppose that someone has figured out what design to change, or do better,
>to avoid "stuck antenna" problems?
>
The problem with Galileo was that it required a Venus flyby to get enough
energy to go to Jupiter.  This necessitated folding up the main antenna so
that it wouldn't be damaged by the close approach to the sun.  The Pluto
direct mission does not need to worry about this, since they will be flying
directly out from Earth to the outer solar system.  The antenna will be
fully opened when placed into the payload fairing of the Titan rocket (there
was an article in yesterday's NY Times on this mission by John Noble Wilford,
and I recommend reading this for anyone interested in this mission).  Actually,
Rob Staehle has an overhead transparency showing what the entire payload would
look like in its fairing (including the two solid upper stage motors), and its
miniscule size is really quite funny.
-------------------------------------------------------------------------------

Irwin Horowitz                        |
Astronomy Department                  |"Whoever heard of a female astronomer?"
California Institute of Technology    |--Charlene Sinclair, "Dinosaurs"
[e-mail]                |
[e-mail]                 |
-------------------------------------------------------------------------------

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

Date: 9 Sep 92 23:03:23 GMT
From: Henry Spencer <[e-mail]>
Subject: Pluto Direct/ options
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Pat) writes:
>Did they consider using energia?  most of the charts I remember
>were using titan or delta class launchers?

Any use of Energia entails the sort of political complications that I
imagine JPL would rather avoid...  I mean complications *within the US*,
not the negotiations with the Russians, which ought to be straightforward
as long as you bring money.  (That was how things worked *before* the
breakup of the USSR, and I imagine it's even more so now...)
--
There is nothing wrong with making      | Henry Spencer @ U of Toronto Zoology
mistakes, but... make *new* ones. -D.Sim|  [e-mail]  utzoo!henry

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

Date: 9 Sep 92 23:14:15 GMT
From: Henry Spencer <[e-mail]>
Subject: Pluto Direct/ options
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (robert.f.casey) writes:
>I suppose that someone has figured out what design to change, or do better,
>to avoid "stuck antenna" problems?

It's really very simple:  don't use a folding antenna.  Or if you must
use one, launch the mission on a shuttle (heresy! heresy! :-)) and unfold
the antenna before upper-stage ignition, so there's somebody around to
*fix* it if it doesn't work.  The antenna on Compton stuck too -- although
in a somewhat different way -- and the shuttle crew went out and fixed it.
--
There is nothing wrong with making      | Henry Spencer @ U of Toronto Zoology
mistakes, but... make *new* ones. -D.Sim|  [e-mail]  utzoo!henry

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

Date: 9 Sep 92 23:19:30 GMT
From: Henry Spencer <[e-mail]>
Subject: Pluto Direct/ options
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Horowitz, Irwin Kenneth) writes:
>The problem with Galileo was that it required a Venus flyby to get enough
>energy to go to Jupiter.  This necessitated folding up the main antenna so
>that it wouldn't be damaged by the close approach to the sun...

Actually, no, the problem with Galileo was that the combination of data
rate, transmitter power, and size constraints made a rigid antenna
impossible.  The Voyager design had the biggest rigid antenna that would
fit in a Centaur payload shroud; nothing in the US inventory could carry
a Galileo-size antenna unless it was folded.

The effect of the Venus flyby was to require that the antenna *stay*
folded for the first year or so in space.  This may or may not have
contributed to the problem.  The back-and-forth shipping needed to make
those modifications quite possibly contributed to the problem.
--
There is nothing wrong with making      | Henry Spencer @ U of Toronto Zoology
mistakes, but... make *new* ones. -D.Sim|  [e-mail]  utzoo!henry

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

Date: 9 Sep 92 22:49:13 GMT
From: "Alan M. Carroll" <[e-mail]>
Subject: Relativity
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Alan Barclay) writes:
> A recent SF book used relativistic mass to produce black holes.
> i.e. accelerate a spaceship until it's massive enough to collapse
> into a singularity.  Something seems missing in this equation.
> Could it happen?

No. Are you sure this was in a book? I remember seeing this in the
"Probability Zero" column of Analog magazine a few years back. It was
a short story that used this effect and was intended as a parody of
bad science fiction writing.

--
Alan M. Carroll          "Weren't there yams involved, too?" - J. Ockerbloom
Epoch Development Team
Urbana Il.               "I hate shopping with the reality-impaired" - Susan

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

Date: 9 Sep 92 21:38:14 GMT
From: Henry Spencer <[e-mail]>
Subject: Single Stage to Orbit - How does it work?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (KEVIN D. DAWSON) writes:
>>except that it will probably use either a "plug nozzle" (which puts the
>>entire base area of the rocket to work as the nozzle) or telescoping
>>nozzles that can be made longer in flight... neither
>>has flown, although both look workable...
>
>I Take it the Telescoping nozzle on the Peacekeepers upper stage doesn't
>count because it only telescopes for storage?

Correct.  There are quite a number of nozzle designs that telescope for
storage but are fully deployed before ignition.  They are common for
applications where nozzle length is a major issue:  submarine-launched
missiles (where a fixed missile-tube volume must be used as efficiently
as possible), treaty-limited missiles (same requirement for a different
reason), and shuttle payloads (the IUS uses telescoping nozzles).  Nobody
has yet flown a nozzle designed to be *fired* in more than one position.
--
There is nothing wrong with making      | Henry Spencer @ U of Toronto Zoology
mistakes, but... make *new* ones. -D.Sim|  [e-mail]  utzoo!henry

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

Date: 9 Sep 92 22:38:51 GMT
From: Henry Spencer <[e-mail]>
Subject: SPS
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (John Roberts) writes:
>-... to develop less expensive
>-technologies for getting lunar material into space, such as
>-electromagnetic mass drivers and powdered aluminum/oxygen rockets.
>
>Ah, one of my favorites! Apparently a private company actually built a
>working aluminum-oxygen rocket last year...

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).
Jordin Kare's latest laser-launcher design, the heat-exchanger rocket,
needs liquid hydrogen for launch from Earth but would work well enough
on liquid oxygen for a lunar launch.  You'd still have to do some of
the same work on chamber/nozzle materials, I expect.

>important, because I think you get the best specific impulse with an excess
>of oxygen, and hot oxygen is bad for most metals.

Your exhaust velocity [specific impulse is exhaust velocity in bizarre
units] will go all to hell without that excess of oxygen, because the
combustion products of that reaction are *solid* at any reasonable
temperature.  To convert heat to jet velocity, you need hot *gas*.
So yes, such a system would have to run very oxygen-rich.
--
There is nothing wrong with making      | Henry Spencer @ U of Toronto Zoology
mistakes, but... make *new* ones. -D.Sim|  [e-mail]  utzoo!henry

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

Date: 10 Sep 92 00:02:52 GMT
From: Jeff Jackson <[e-mail]>
Subject: Terraforming needs to begin now
Newsgroups: sci.space

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?



--
============================================================================
Jeffrey Glen Jackson  _|_Satan jeered, "You're dead meat Jesus, I'm gonna
[e-mail] |     bust you up tonight."
x5120                  | Jesus said, "Go ahead, make my day."
                   ~~~~~~~~~ -- Carman, "The Champion"
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
    Politically, I am neither conservative nor liberal --
             I think for myself instead.

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

Date: 9 Sep 92 23:00:37 GMT
From: Henry Spencer <[e-mail]>
Subject: use of external tanks
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Michael K. Heney) writes:
>the current direct-ascent trajectories used on shuttle launches has the
>orbiter climbing to apogee and the tank re-entering after MECO, with no
>burns to alter either's trajectory...

For those who didn't read the above carefully :-), note in particular that
*it is no longer true* that the shuttle expends fuel just to get the tank
into a disposal trajectory.  Taking it into orbit, even low orbit, will
cost you.

To expand on Michael's general point, the tanks won't stay in orbit long
because they are big and light and very vulnerable to air drag.  This is
especially true because, left to themselves, they will stabilize with
the long axis pointing along the tank-Earth line, which puts them
broadside-on to orbital motion -- the worst possible case for air drag.

It is Politically Unacceptable to just let them come down anywhere.
You have to be able to either keep them up or deorbit them under control,
with a very high probability of success (i.e. you need redundant systems).

Another significant point is that any large, light structure has to count
on being punctured by space debris.  The Gamma-Ray Imaging Telescope
concept -- the most detailed study on ET use that I know of -- planned to
wrap an outer blanket around the entire tank once on orbit, both to act
as a "meteor bumper" and to contain popcorning insulation.

>There *is* an access "hatch" on the bottom of the LH2 tank - 3 feet in
>diameter and bolted on *very* securely...

In fact there are two, although one is obstructed by some of the internal
plumbing.  There is also one in the top of the LH2 tank (letting you into
the intertank space), one in the bottom of the LO2 tank (ditto), and a
door in the side of the intertank ring (giving you access to those hatches).
Getting access to any of them is going to require cutting away the spray-on
insulation, by the way.

>... Now, you need to somehow add on a
>*real* airlock, build internal structures, add power supplies, plumbing,
>windows, etc,  all of which involves cutting and welding on orbit by
>astronauts on EVA...

Actually, you can shortcut this a lot by using the technique planned for
the original "wet workshop" Skylab concept:  once the hatch cover is off,
insert a cylinder 3ft in diameter and the length of the tank (actually,
you'd probably have to join two pieces end-to-end to get that length from
something fitting the shuttle cargo bay).  Bolt it down where the hatch
used to be.  The outside end of the cylinder contains your airlock,
which can stay *outside* and hence be any convenient diameter; only the
inserted part is limited to 3ft in diameter.  That part is packed as
solidly as you can with parts, plumbing, etc.; it becomes your utility
core, while things like structure can be assembled -- by people in
shirtsleeves, inside the pressurized tank -- from the parts.
--
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 181
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