Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/spacedig/v15_1/v15no182.txt

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Date: Thu, 10 Sep 92 05:09:52
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #182
To: Space Digest Readers
Precedence: bulk


Space Digest                Thu, 10 Sep 92       Volume 15 : Issue 182

Today's Topics:
                         3 booster questions
                               Dry DNA
                    farthest Laser signal (4 msgs)
         Is NASA really planning to Terraform Mars? (2 msgs)
                   LDO shuttle and pilot readiness
          One Small Step for a Space Activist... Vol 3 No 9
                        Pluto Direct/ options
                   QUERY Re: Pluto Direct/ options
                              Relativity
      Shuttle tank for habitation; was Inflatable Space Stations
                      Terraforming Mars (2 msgs)
               Terraforming needs to begin now (2 msgs)
         With telepresence, who needs people in Earth orbit?

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Date: 10 Sep 92 05:23:22 GMT
From: Brett Vansteenwyk <[e-mail]>
Subject: 3 booster questions
Newsgroups: sci.space

[1].What makes Titan so expensive?  I would think that this would be a
mature launch system where no one needs to masturbate the machinery before
launch.  Is there something inherent in its properties (such as long storage
fuel tanks?) or is it in the way the system is managed?

[2].Atlas still goes *boom* a lot?  Is this inherent to the design of having
two of the engines fall off and the difficulty in shutting off the fuel flow
to these engines?

[3].It seems, like it or not, that the Shuttle will be flying for at least 10
more years.  Perhaps developing an LRB for the Shuttle will not be justified
on its own.  Perhaps developing an HLV will not be justified on its own.
However, if you have an HLV whose first stage will also serve as an LRB
you could amortise development costs pretty fast.  Is there something wrong
with this idea?
    For example, a single engine "Baby Saturn" based on the F1A may qualify.
If modifying the External Tank design for 3 boosters instead of 2 is not
difficult, and if there is no particular reason that you cannot ride the
Shuttle on "top" of the stack instead of the the bottom (angle of attack
considerations would force this change), then you would have a ready use
for 25-30 of these vehicles per year.  Why not?

            --Brett Van Steenwyk

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

Date: 10 Sep 92 04:09:05 GMT
From: John Roberts <[e-mail]>
Subject: Dry DNA
Newsgroups: sci.space

-From: [e-mail] (Paul Dietz)
-Subject: Re: Is NASA really planning to Terraform Mars?
-Date: 8 Sep 92 00:43:18 GMT

-The surface of Mars is extremely dry.  All terrestrial life requires
-liquid water to survive.  Even bacterial spores are quickly rendered
-nonviable in extreme dryness: experiments that place spores in air of
-near-zero relative humidity at 25 C find that the DNA begins to
-degrade, and the spores become nonviable within weeks (for this
-reason, the bacteria that supposedly survived in the Surveyor on the
-moon were likely post-recovery contaminants).

I hadn't heard that one before. What about lotus seeds and water bears?
I understood water bears could survive dehydration indefinitely if placed
in a non-oxygen atmosphere. Lotus seeds have a mechanism that tends to make
them increasingly dry over time, yet remain viable for thousands of years.
A lotus seed in a sheltered spot in the Egyptian desert ought to get pretty
dry over time. I believe brine shrimp eggs last quite a while when dry
too. Mars tends to be drier than Earth, but also colder.

I understand researchers recently recovered DNA sequences from ancient bees
that were trapped in amber millions of years ago.

I agree with you that there's no known location on Mars where any known form
of Earth life could be active.

John Roberts
[e-mail]

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

Date: Wed, 9 Sep 1992 23:48:07 GMT
From: Henry Spencer <[e-mail]>
Subject: farthest Laser signal
Newsgroups: sci.space

In article <[e-mail]> [e-mail] ("Richard Schroeppel") writes:
>Note that radar signals have been bounced off Venus, and were
>actually used for some mapping...

I believe JPL has done interplanetary radar work as far as Jupiter.

>Assuming the purpose of your question is to consider "How feasible
>are lasers for high bandwidth, semi-private, space communication?"...

Feasible.  There is intense interest in the idea, and some in-space
experiments will fly in this decade.  (It's just possible that secret
military systems might be operational already -- laser communications
systems would have very tight beams that would be very difficult to
eavesdrop on.)
--
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 02:13:09 GMT
From: "Michael V. Kent" <[e-mail]>
Subject: farthest Laser signal
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>In article <[e-mail]> [e-mail] ("Richard Schroeppel") writes:
>>Assuming the purpose of your question is to consider "How feasible
>>are lasers for high bandwidth, semi-private, space communication?"...
>
>Feasible.  There is intense interest in the idea, and some in-space
>experiments will fly in this decade.

Forgive my not knowing the basic vocabulary, but is this what's known as a
lidar (laser radar?)?  If so, the Lidar In-Space Technology Experiment is
scheduled for a 1994 launch.

>It's just possible that secret
>military systems might be operational already -- laser communications
>systems would have very tight beams that would be very difficult to
>eavesdrop on.)

I know work is active in this area, but has anything flown yet?

Mike


--
Michael Kent                                   [e-mail]
McDonnell Douglas                              Rensselaer Polytechnic Institute
All facts in this post are based on publicly available information.  All
opinions expressed are solely those of the author.    Apple II Forever !!

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

Date: 10 Sep 92 10:07:50 GMT
From: Ron Baalke <[e-mail]>
Subject: farthest Laser signal
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Henry Spencer) writes...
>In article <[e-mail]> [e-mail] ("Richard Schroeppel") writes:
>>Note that radar signals have been bounced off Venus, and were
>>actually used for some mapping...
>
>I believe JPL has done interplanetary radar work as far as Jupiter.

Try a little further out, like Saturn.  Radar has been bounced off of
Titan using the high power transmitter on the 70 meter antenna at Goldstone.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     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: 10 Sep 92 02:20:40 GMT
From: Josh 'K' Hopkins <[e-mail]>
Subject: farthest Laser signal
Newsgroups: sci.space

[e-mail] (Henry Spencer) writes:

>In article <[e-mail]> [e-mail] ("Richard Schroeppel") writes:
>>Note that radar signals have been bounced off Venus, and were
>>actually used for some mapping...

>I believe JPL has done interplanetary radar work as far as Jupiter.

As a matter of fact, I think someone has gone so far as to bounce radar off
Titan in an attempt to guess what the surface was.  However, unless we're using
different definitions, radar and laser are acronyms for two different things.

>>Assuming the purpose of your question is to consider "How feasible
>>are lasers for high bandwidth, semi-private, space communication?"...

>Feasible.  There is intense interest in the idea, and some in-space
>experiments will fly in this decade.  (It's just possible that secret
>military systems might be operational already -- laser communications
>systems would have very tight beams that would be very difficult to
>eavesdrop on.)

There is a proposed experiment to be launched by the Japanese which would try to
talk to a European sattelite.  However, like almost all the payloads Japan is
planning, its rocket is still under development.

--
Josh Hopkins           "If you are sitting in an exit row and you cannot read
                       this card or cannot see well enough to follow these
               instructions, please tell a crew member."
[e-mail]                       -United Airlines safety instructions

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

Date: 10 Sep 92 01:15:39 GMT
From: Joe Cain <[e-mail]>
Subject: Is NASA really planning to Terraform Mars?
Newsgroups: sci.space,sci.astro,sci.geo.geology

There is an article of non-fiction in the October "Analog" (=old ASF)
by Martyn J. Fogg regarding the futility of now attempting to
terraform Mars. One of the references he quotes implies that he was the
editor of the Journal of the British Interplanetary Society (at least
in 1991).

I would like to see some critiques or comments by those who have
looked seriously into this subject regarding his article. (pp. 60-77)
To a novice like myself his arguments appear reasonable.

I particularly would like to understand the "carbonate-silicate" cycle
he ascribes to a James Walker et al from the University of Michigan
ca. 1981 but otherwise for which no reference is given. (He does refer
to the December 1989 and April 1991 issues of the BIS, which is not
easily obtainable here, plus a couple of other books I have not had
time to check:
S. K. Atreya et al (editors) Origin and evolution of planetary and
satellite atmospheres, U. of Arizona Press (1989)
and Mallove, E., and G. Matloff, The starflight handbook, Wiley ,
1989.)


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

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

Date: 10 Sep 92 05:04:35 GMT
From: Frank Crary <[e-mail]>
Subject: Is NASA really planning to Terraform Mars?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (David Knapp) writes:
>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.

I'd have to disagree on two points: I don't think there is any evdence
we are making the Earth "unlivable." In some respects, we may have
made it a less pleasent place to live, but that is a very different
thing from uninhabitable. I hope you aren't suggesting absolute
prefection with respect to the Earth's environment should be a
pre-requsite to extra-planetary ventures.

Second, since there is no live on Mars, nor anywhere else in the
Solar System, excatly who's backyard is Mars, if not our own?

                                                    Frank Crary
                                                    CU Boulder

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

Date: 10 Sep 92 02:06:59 GMT
From: "Michael V. Kent" <[e-mail]>
Subject: LDO shuttle and pilot readiness
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>In article <[e-mail]> [e-mail] (Gary Coffman) writes:
>>... 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.

Yes, but isn't Autoland scheduled for test on STS-53 in November?  I remember
a blurb about it in AvWeek this summer and another in the Shuttle status
reports about a month ago.

Speaking of STS-53, is this mission classified?  STS-38 was launched two
years ago with much fanfare over its being the last classified Shuttle
mission.  Then it STS-38 made an unscheduled landing in Florida (the first
in the post-51L era), and STS-53 was very quietly added to the manifest.
What's the deal?

Mike

--
Michael Kent                                   [e-mail]
McDonnell Douglas                              Rensselaer Polytechnic Institute
All facts in this post are based on publicly available information.  All
opinions expressed are solely those of the author.    Apple II Forever !!

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

Date: 10 Sep 92 03:27:53 GMT
From: "Michael V. Kent" <[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:
>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

NASA intends to use only the Shuttle for resupply ONLY until something
better comes along.  Also, one of the design missions of the Delta Clipper
is station resupply.

>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.

The mistake here is thinking of the Shuttle as a launch vehicle.  It is not.
A second mistake is thinking its sole mission is Station resupply.  That, too,
is untrue.  If Station resupply is offloaded to another vehicle, you still
want to keep the Shuttle around for missions like EURECA, TSS, SHARE, CIRRUS,
Hubble revisits, satellite repair, retrieving, and servicing, etc.  These
are missions which still need to be done and that the Shuttle was designed to
do.

Remember, the Shuttle is not a launch vehicle.  It is a space transportation
system (hence the acronym STS).  It includes things like the OMS and RCS for
multiple satellite rendezvous, the robot arm, astronauts-on-demand for
contingency spacewalks, the MMU, Spacelab, the Spacelab mounting hardware
(for things like Astro), the Shuttle Palette Satellite, and some things
harder to quantify like the attitude control capability (essential for
missions like Astro and STS-39).

Your station resupply vehicle will offer few of those things.  It is a
valuable first step but a small one.  It will not replace the Shuttle.

>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).

Please note two things.  NASA would like to go to a 180-day rotation about
two years after PMC (instead of 90 days).  Also, NASA plans to expand the
station to an eight man crew (EMCC).  Plan your vehicle accordingly.

>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).

I like the heavy-lift idea, but I don't think they fill the mission well.
It seems like you're adapting a mission to the vehicle and not the other
way around.  (You could argue NASA is doing the same with the Shuttle, but
the Shuttle already exists.  These vehicles do not).  If you're going to
build a new vehicle, build it to the mission requirements.  (If I were
a station manager, I'd rather have 5 flights of 20,000 lbs each than one
flight of 100,000 lbs.  It offers much more flexibility).

>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

You want to use an Atlas?  The rocket that goes "boom" a lot?  (Rockets
should go roooar, not boom  :)  ).  We used to launched manned missions
on the Atlas, but we didn't have much of a choice then.

>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.

I think you want the Orbital Maneuvering Vehicle (OMV).  The OTV was meant
to move payloads between LEO and GEO.  (An OTV is nice, but we need an OMV
first).

Mike

--
Michael Kent                                   [e-mail]
McDonnell Douglas                              Rensselaer Polytechnic Institute
All facts in this post are based on publicly available information.  All
opinions expressed are solely those of the author.    Apple II Forever !!

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

Date: 10 Sep 92 04:33:08 GMT
From: Dave Tholen <[e-mail]>
Subject: Pluto Direct/ options
Newsgroups: sci.space

Robert 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 current spacecraft design has a fixed antenna, not a deployable antenna
like Galileo.  Note that the data rates we're talking about with the Pluto
spacecraft aren't that much higher than Galileo's data rate through the
low gain antenna.  It's a tradeoff of mass versus data rate.  We can get
the data rate up, but only by using either a larger antenna or a more
powerful transmitter, which requires more electricity.  Either way, the
spacecraft mass goes up, so you either travel more slowly to Pluto or you
use a more powerful booster, which also adds to the cost.  The design
tradeoffs are rather involved.

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

Date: Wed, 9 Sep 1992 23:10:23 GMT
From: Henry Spencer <[e-mail]>
Subject: QUERY Re: Pluto Direct/ options
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Tom A Baker) writes:
>Could you clarify whether this craft is supposed to just flyby (a la
>Voyager) or is truly a Pluto "orbiter"? ...

It is extremely difficult to combine a reasonable payload and a manageably
short trip time with an orbiter mission.  Pluto is *a long way away*; to
get there in under a decade, the probe has to be fast.  Killing all that
velocity is inordinately expensive in mass.  You really cannot do a Pluto
orbiter in a reasonable amount of time with 1960s propulsion technology,
which is what all currently-planned missions use.
--
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 04:20:45 GMT
From: John Roberts <[e-mail]>
Subject: Relativity
Newsgroups: sci.space

-From: [e-mail] (Alan Barclay)
-Subject: Re: Relativity
-Date: 9 Sep 92 07:21:06 GMT
-Organization: MIND LINK! - British Columbia, Canada

-What I was trying to simplify is the following:

-1) Observer starts at v=0 relative to stars A and B.  He starts at Star A.
-2) Observer measures distance to star B = 4 ly.
-3) Observer accelerates to a high relativistic speed travelling towards
-star B, turns over halfway and decelerates to v=0 relative to star B
-adjacent to star b.  During this time he makes no measurements except to
-keep track of subjective time passed.
-4) When he steps onto the surface of a planet around star B, he can look
-back at star A, measure it as 4 ly away, and know it took him less than
-four (subjective) years to get there.

-It seems to me that it is possible to travel at greater than 1 ly per
-year FROM A CERTAIN POINT OF VIEW, and that point of view is valid,
-in that it would have real experiential consequences on a traveller.

That's true. It's also true that if human cryogenic storage is ever perfected,
the astronaut could be frozen for the entire duration of the trip on a
spacecraft moving at only a tiny fraction of c. Even if the ship's
chronometer indicates that 10000 years of ship time passed, from the
astronaut's point of view, the trip was instantaneous, and thus the
velocity was therefore infinite.

John Roberts
[e-mail]

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

Date: 10 Sep 92 05:08:08 GMT
From: Frank Crary <[e-mail]>
Subject: Shuttle tank for habitation; was Inflatable Space Stations
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (USENET System Software) writes:
>Why not orbit the tank with solid fule trap-on boosters and
>build them with an access hatch?

There are two problems (neither unsolvable): There would be no
internal hardware (live support, research equipment, etc...) and
there would be a pressing, immediate need for station keeping
rockets: Due to the low mass/cross sectional area of an external
tank, one on orbit would de-orbit from atmospheric drag very
soon (months I think).

                                              Frank Crary
                                              CU Boulder

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

Date: 10 Sep 92 04:11:39 GMT
From: John Roberts <[e-mail]>
Subject: Terraforming Mars
Newsgroups: sci.space

-From: [e-mail] (Thomas H. Kunich)
-Subject: Re: Is NASA really planning to Terraform Mars?
-Date: 7 Sep 92 23:55:32 GMT
-Organization: Netcom - Online Communication Services  (408 241-9760 guest)

-It is a simple, possibly even elementary, matter to find
-various bacteria, algae, fungi, lichen etc. that can exist
-in the harsh environment of Mars. Or, for that matter, the
-upper reaches of the Venusian atmosphere. These life-forms
-are small, light and quite capable of being transported in
-rather massive quantities to these planets by presently
-possessed technology.

It's probably harder than you think. The main challenge on Mars is not
necessarily the scarcity of water (though that is a major problem), but
finding a location where they can get the energy to support life processes
without being killed by the UV in the sunlight or the reducing soil that
destroys organic matter.

-Should there not be appropriate life
-forms, our present knowledge of biotechnology should lead
-us to be able to develop some in fairly short order.

We should think twice before deliberately producing microorganisms that
can survive some of our best sterilization techniques. Remember that in the
realm of microorganisms, "recombinant DNA" isn't something that happens only
with human assistance.

-I suggest that we send a space vessel bearing our life
-substitutes to Mars and Venus. The cost is relatively
-miniscule. Thereon we can sprinkle the makings of man
-himself.

I suggest we make sure we understand the matter thoroughly before we try
anything. This is not a good area for trial and error. (Remember Asimov's
novel "Foundation and Earth".)

John Roberts
[e-mail]

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

Date: 10 Sep 92 06:58:13 GMT
From: Nick Janow <[e-mail]>
Subject: Terraforming Mars
Newsgroups: sci.space

[e-mail] (John Roberts) writes:

> It's probably harder than you think. The main challenge on Mars is not
> necessarily the scarcity of water (though that is a major problem), but
> finding a location where they can get the energy to support life processes
> without being killed by the UV in the sunlight or the reducing soil that
> destroys organic matter.

Does it destroy _all_ organic material (carbon, hydrogen, nitrogen material),
or is there a molecule that can convert UV photons to chemical energy without
being destroyed?  Even if no organic molecule could manage that, there are
other possibilities.  What of a microorganism (similar to Terran types) that
fills a silicone or silica bubble with inorganic chemicals that can be split to
form useful chemical energy (H2 and O2, for example)?  It could shove the
bubbles above the sand, while the body is deep below, connected by silicone
tubes.

The entire organism could be underground, using silica fibres to the surface as
light pipes.  I think some Terran life forms use something like this (there are
plants that use light pipes).

Limiting your thoughts to Terran organic processes leaves out a _lot_ of
possibilities.

--

[e-mail]

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

Date: 10 Sep 92 02:24:46 GMT
From: Josh 'K' Hopkins <[e-mail]>
Subject: Terraforming needs to begin now
Newsgroups: sci.space

[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.

This might work, and I believe something similar but but on a smaller scale and
using aquifers is being tried in Lybia.  The trouble is that big projects like
this are _big_ and expensive.  A cheaper way to do it is Chinas "green Great
Wall" approach.  They are planting millions of plants in the northwest, and
using sattelite imagery to pick the best spots.


>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.
--
Josh Hopkins           "If you are sitting in an exit row and you cannot read
                       this card or cannot see well enough to follow these
               instructions, please tell a crew member."
[e-mail]                       -United Airlines safety instructions

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

Date: 10 Sep 92 08:32:13 GMT
From: [e-mail]
Subject: Terraforming needs to begin now
Newsgroups: sci.space

In <[e-mail]> Jeff Jackson writes:
> -- description of terraforming the outback deleted for brevity --
  Believe it or not, in OZ we actually think about things like this.
   Our problem is that the outback is dead flat. There's nothing to
interrupt the moisture laden air coming off the coast. Without this,
it cannot rise and precipitate.
   The coolest idea I know of, was to cover vast (strategically located)
areas with tar/black paint etc. to create hot spots that would form
artificial mountains. Do this properly and you can get a convection
cycle going, that will bring moisture laden air in from the coast,
and cause it to precipitate on the upwind border of your 'parking lot'
 -----------------------------------------------------------------
               ** Of course I don't speak for IBM **
Greg Nicholls ... [e-mail] or [e-mail]
                  voice/fax: [phone]

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

Date: Wed, 9 Sep 1992 23:40:35 GMT
From: Henry Spencer <[e-mail]>
Subject: With telepresence, who needs people in Earth orbit?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Thomas Clarke) writes:
>> It's absurd to tie teloperation in low earth orbit to a communication
>> path involving two round trips to Clark orbit.  Build a necklace of
>> co-orbiting microsats ...
>
>Easier still, use the Motorola Iridium constellation...

Both of these ideas assume that the delay *around the Earth* is tolerable
for teleoperation.  Probably true for the simpler forms, but I've heard
some very low numbers for the tolerable delay if you're using the fancier
methods like force feedback.
--
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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    id AA01175; Wed, 9 Sep 92 21:58:48 EDT
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From: Henry Spencer <[e-mail]>
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Subject: Re: Is NASA really planning to Terraform Mars?
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In article <[e-mail]> [e-mail] (Andreas Michael Weder) writes:
>I'd say, forget about that. Even a manned mission to Mars would cost
>*at least* 500 billion dollars (according to a NASA researcher).

According to a NASA politician, you mean.

There is no technical reason why it has to cost that much.  See Bob Zubrin's
"Mars direct" proposal for an example of a method that ought to cost about
a tenth that much, total, for the first ten missions.  If enough people prod
me, I'll type in my notes from his talk, although there was a good summary
paper about it a year or two ago in JBIS.
--
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 182
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