Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT_ZIP/spacedig/V16_3/V16NO335.ZIP/V16NO335

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Date: Fri, 19 Mar 93 05:00:12
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V16 #335
To: Space Digest Readers
Precedence: bulk


Space Digest                Fri, 19 Mar 93       Volume 16 : Issue 335

Today's Topics:
                                 DC-X
                      Galileo Update - 03/15/93
                      How to cool Venus (2 msgs)
                  Need Info on GOES 2 Move Last Year
                      plans, and absence thereof
                  Response to various attacks on SSF
               Semi-technical aspects of SSTO (repost)
                     SR-71 Maiden Science Flight
                      Tidal lock, magnetic field
                     Veneraforming (sp?) (2 msgs)
                          what's new at nasa
                   What do we do now with Freedom.

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

Date: 18 Mar 93 12:56:05 GMT
From: FRANK NEY <tnc!m0102>
Subject: DC-X
Newsgroups: sci.space

I just wish we could fund DC-X and DC-Y privately.  Unfortunately,
CSLA makes this a near-impossibility.
--
The Next Challenge - Public Access Unix in Northern Va. - Washington D.C.
703-803-0391 To log in for trial and account info.

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

Date: 17 Mar 93 13:09:44 GMT
From: Rui Sousa <[e-mail]>
Subject: Galileo Update - 03/15/93
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Ron Baalke) writes:

   ...

    Over the weekend, spacecraft activity to map the High Gain Antenna
   receive gain pattern was performed on Saturday, as planned.  Tracking was
   ...

Does this mean there is still hope the HGA might be used even in its partially
folded condition?

Rui




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

                All opinions expressed here are strictly my own

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

Date: 18 Mar 1993 13:32:24 GMT
From: Eric Rothoff <[e-mail]>
Subject: How to cool Venus
Newsgroups: sci.space

I agree that cooling down Venus is necessary.  You would need to both import
hydrogen and export lots of oxygen to decrease the density of the atmosphere.
This could be useful in other terraforming projects, fuel for space
exploration, and supplying various space communities. (of course this is FAR
FAR in the future.

Eric

--
********************************************************
*  Eric G. Rothoff      *   "Life is a game, LIVE IT!  *
*  [e-mail]  *      don't hide from it.     *
********************************************************

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

Date: Thu, 18 Mar 1993 18:38:07 GMT
From: Nick Haines <[e-mail]>
Subject: How to cool Venus
Newsgroups: sci.space

We can't use photosynthesis to do anything with Venus because
photosynthesis traps water. nCO2 + nH2O -> saccharides. Venus has
almost no water. We must either provide that water _before_
photosynthesis will take hold or we must get rid of the CO2 in some
other way.

To get the water you need to import either hydrogen (all that oxygen
in the CO2) or water itself. Hydrogen is difficult to transport in the
quantities under consideration, whereas water is simple: it's just ice
after all. How much water? Well, the mass of the Earth's atmosphere is
about 5e18 kg (useful figure to know), so we're talking that order of
magnitude (You don't need as much water as CO2, but you need a whole
lot and Venus has ~100 times as much atmosphere as Earth).  Hey,
that's only 80 million comets (assuming 5km average size). Looks like
a job for Nick Szabo's visionary robots.

The alternative is to get rid of the CO2 some other way. Chemically,
the best thing to do with it is to turn it into carbonate ions (CO3).
If you bond a carbonate ion with pretty much anything you get a solid
(much of the Earth's crust is formed of carbonate rocks). The easiest
way to get carbonate ions is to get the extra oxygen from water, but
the alternative is to manage some sort of nCO2 -> mCO3 + pC process. I
don't know if this is energetically possible.

Either way you need some kind of self-reproducing robots out (in the
Oort cloud?)  collecting icy bodies and lobbing them at Venus or some
kind of self-reproducing robots running chemical factories on Venus.
You can't terrraform Venus without an exponential process, you can't
use existing ones (i.e. life) because the conditions are too extreme,
so you must build a new one.

When we develop that kind of technology, terraforming Venus will be
one of the less impressive things we can do with it.

Nick Haines [e-mail]

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

Date: 18 Mar 93 12:50:29 GMT
From: "Richard B. Langley" <[e-mail]>
Subject: Need Info on GOES 2 Move Last Year
Newsgroups: sci.space

During July, August, and September 1992, GOES 2 was moved from about
59 degrees W to about 138 degrees W.  Would anyone happen to know the
exact days on which the delta Vs were carried out?  This satellite has
a VHF beacon which is used for Faraday rotation studies and we need
to know where the satellite was each day.  I have TS Kelso's element
sets and have deduced that the initial delta V was between 19 and 26
July and the final delta V between 21 and 30 September but I would like
to narrow these down to the actual day.  Thanks.

==============================================================================
 Richard B. Langley                        Internet: [e-mail] or [e-mail]
 Geodetic Research Laboratory              BITnet:   LANG@UNB or SE@UNB
 Dept. of Surveying Engineering            Phone:    [phone]
 University of New Brunswick               FAX:      [phone]
 Fredericton, N.B., Canada  E3B 5A3        Telex:    014-46202
==============================================================================



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

Date: Thu, 18 Mar 1993 14:24:50 GMT
From: "Dr. Norman J. LaFave" <[e-mail]>
Subject: plans, and absence thereof
Newsgroups: sci.space,alt.sci.planetary

In article <[e-mail]> Nick Szabo, [e-mail]
writes:
> This is a truly stupid comment.  Wingo gets 100% of his paycheck
> from the IRS and pays back 20-30%.  BFD.

God Nick! Is this nitpicking, venomous tripe really necessary? Does
a person have to agree with you in order to be treated with respect?
Please Nick.....I don't agree with much of what you say, but I do agree
with some of it. Dennis may even find value in projects you consider
worthy. However, it is the nature of the beast to be multi-headed.
Successful space exploration and exploitation will require both
manned and unmanned efforts, small and large projects, short-term
and long-term R&D, commercial and publicly funded research. Bad-
mouthing the efforts of others will only result in the death of all
efforts. Need I point out that money cut from NASA's budget has
NEVER gone into other space or scientific funding pools?

Norman

Dr. Norman J. LaFave
Senior Engineer
Lockheed Engineering and Sciences Company




When the going gets weird, the weird turn pro
                               Hunter Thompson

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

Date: Thu, 18 Mar 1993 14:31:50 GMT
From: "Dr. Norman J. LaFave" <[e-mail]>
Subject: Response to various attacks on SSF
Newsgroups: sci.space

In article <[e-mail]> ,
[e-mail] writes:
> The primary problem that was faced on the Intelsat mission is that the
> tank simply cannot accurately mimic the moments of inertia of large
> structures in orbit.  Maybe they need to look at regimens to compensate
> better for this difference between water and vaccuum.

Indeed, it seems that some engineers needed to go back and take
a remedial mechanics class. The problem was not the tank, the
problem was the lack of full rotational dynamics of the intelsat
mock-up. They failed to treat it as a body with full 3-axis rotational
freedom. Precession due to off-axis disturbances were not properly
considered. The design of the capture arm was doomed to failure,
because the chances of locking one side of the arm to INTELSAT without
causing precession were extremely small. This has little to do with the
tank.

Norman

Dr. Norman J. LaFave
Senior Engineer
Lockheed Engineering and Sciences Company




When the going gets weird, the weird turn pro
                               Hunter Thompson

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

Date: Thu, 18 Mar 1993 14:03:12 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: Semi-technical aspects of SSTO (repost)
Newsgroups: sci.space

[This is a repost of Henry's article written for the Freshmen Orientation
 Project - sans resume (no idea how that got there)]


(Semi-)Technical Aspects of SSTO by Henry Spencer

This paper will try to give you some idea of why SSTO makes technical
sense and is a reasonable idea.  We'll concentrate on the overall issues,
trying to give you the right general idea without getting bogged down
in obscure detail.  Be warned that we will oversimplify a bit at times.

Why Is SSTO Challenging?

Getting a one-stage reusable rocket into orbit doesn't look impossible,
but it does look challenging.  Here's why.

The hard part of getting into orbit is not reaching orbital altitude,
but reaching orbital velocity.  Orbital velocity is about 18,000mph.
To this, you have to add something for reaching orbital altitude and for
fighting air resistance along the way, but these complications don't
actually add very much.  The total fuel requirement
is what would be needed to accelerate to 20-21,000mph.

So how much is that?  (If you don't want to know the math, skip to the
next paragraph for the results.)  The "rocket equation" is
desired_velocity = exhaust_velocity * ln(launch_weight / dry_weight),
where "ln" is the natural logarithm.  The exhaust velocity is determined
by choice of fuels and design of engines, but 7,000mph is about right
if you don't use liquid hydrogen, and 10,000mph if you do.

The bottom line is that the launch weight has to be about 20 times the
dry weight (the weight including everything except fuels) if you don't
use liquid hydrogen, and about 8 times the dry weight if you do.  This
sounds like hydrogen would be the obvious choice of fuel, but in practice,
hydrogen has two serious problems.  First, it is extremely bulky,
meaning that hydrogen tanks have to be very big; the Shuttle External
Tank is mostly hydrogen tank, with only the nose containing oxygen.
Second, some of the same properties that make hydrogen do well on the
weight ratio make it difficult to build hydrogen engines with high thrust,
and a rocket *does* need enough thrust to lift off!  Both of these
problems tend to drive up the dry weight, by requiring bigger and heavier
tanks and engines.

So how bad is this?  Well, it's not good.  Even with hydrogen, an SSTO
launcher which weighs (say) 800,000lbs at launch has to be 7/8ths fuel.
We've got 100,000lbs for tanks to hold 700,000lbs of fuel, engines to
lift an 800,000lb vehicle, a heatshield to protect the whole thing on
return, structure to hold it all together at high acceleration... and
quite incidentally, for some payload to make it all worthwhile.  Most
of the dry weight has to go for the vehicle itself; only a small part
of it can be payload.  (That is, the "payload fraction" is quite small.)
To get any payload at all, we need to work hard at making the vehicle
very lightweight.

The big problem here is:  what happens if the vehicle isn't quite as
light as the designer thought it would be?  All rockets, and most aircraft
for that matter, gain weight during development, as optimistic estimates
are replaced by real numbers.  An SSTO vehicle doesn't have much room for
such weight growth, because every extra pound of vehicle means one less
pound for that small payload fraction.  Particularly if we're trying to
build an SSTO vehicle for the first time, there's a high risk that the
actual payload will be smaller than planned.

That is the ultimate reason why nobody has yet built an SSTO space
launcher:  its performance is hard to predict.  Megaprojects like the
Shuttle can't afford unpredictability -- they are so expensive that
they must succeed.  SSTO is better suited to an experimental vehicle,
like the historic "X-planes", to establish that the concept works and
get a good look at how well it performs... but there is no X-launcher
program.

Why Does SSTO Look Feasible Now?

The closest thing to SSTO so far is the Atlas expendable launcher.  The
Atlas, without the Centaur upper stage that is now a standard part of
it, has "1.5" stages:  it drops two of its three engines (but nothing
else) midway up.  Without an upper stage, Atlas can put modest payloads
into orbit:  John Glenn rode into orbit on an Atlas.  The first Atlas
orbital mission was flown late in 1958.  But the step from 1.5 stages
to 1 stage has eluded us since.

Actually, people have been proposing SSTO launchers for many years.
The idea has always looked like it *just might* work.  For example,
the Shuttle program looked at SSTO designs briefly.  Mostly, nobody has
tried an SSTO launcher because everybody was waiting for somebody else
to try it first.

There are a few things that are crucial to success of an SSTO
launcher.  It needs very lightweight structural materials.  It needs
very efficient engines.  It needs a very light heatshield.  And it
needs a way of landing gently that doesn't add much weight.

Materials for structure and heatshield have been improving steadily
over the years.  The NASP program in particular has helped with this.
It now looks fairly certain that an SSTO can be light enough.

Existing engines do look efficient enough for SSTO, provided they can
somehow adapt automatically to the outside air pressure.  The nozzle
of a rocket engine designed to be fired in sea-level air is subtly
different from that of an engine designed for use in space, and an
SSTO engine has to work well in both conditions.  (The technical
buzzword for what's wanted is an "altitude-compensating" nozzle.)
Solutions to this problem actually are not lacking, but nobody has
yet flown one of them.  Probably the simplest one, which has been
tentatively selected for DC-Y, is just a nozzle which telescopes,
so its length can be varied to match outside conditions.  Making
nozzles that telescope is not hard -- many existing rocket nozzles,
like those of the Trident missile, telescope for compact storage --
but nobody has yet flown one that changes length *while firing*.
However, it doesn't look difficult, and there are other approaches
if this one turns out to have problems.

We'll talk about landing methods in more detail later, but this is one
issue that will be resolved pretty soon.  The primary goal of the DC-X
experimental craft is to fly DC-Y's landing maneuvers and prove that
they will work.

So... with materials under control, engines looking feasible, and
landing about to be test-flown, we should be able to build an SSTO
prototype:  DC-Y.  The prototype's performance may not quite match
predictions, but if it works *at all*, it will make all other launchers
obsolete.

Why A Rocket?

As witness the NASP (X-30) program, air-breathing engines do look like
an attractive alternative to rockets.  Much of the weight of fuel in
a rocket is oxygen, and an air-breathing engine gets its oxygen from
the air rather than having to carry it along.  However, on a closer
look, the choice is not so clear-cut.

The biggest problem of using air-breathing engines for spaceflight is
that they simply don't work very well at really high speeds.  An
air-breathing engine tries to accelerate air by heating it.  This works
well at low speed.  Unfortunately, accelerating air that is already
moving at hypersonic speed is difficult, all the more so when it has
to be done by heating air that is already extremely hot.  The problem
only gets worse if the engine has to work over an enormous range of
speeds:  NASP's scramjet engines would start to function at perhaps
Mach 4, but orbital speeds are roughly Mach 25.  Nobody has ever built
an air-breathing engine that can do this... but rockets do it every week.

Air-breathing engines have other problems too.  For one thing, to use
them, one obviously has to fly within the atmosphere.  At truly high
speeds, this means major heating problems due to air friction.  It
also means a lot of drag due to air resistance, adding to the burden
that an air-breathing engine has to overcome.  Rocket-based launchers,
including SSTO, do most of their accelerating in vacuum, away from
these problems.

Perhaps the biggest problem of air-breathing engines for spaceflight
is that they are *heavy*.  The best military jet engines have thrust:weight
ratios of about 8:1.  (This is at low speed; hypersonic scramjets are not
nearly that good.)  The Space Shuttle Main Engine's thrust:weight ratio,
by comparison, is 70:1 (at any speed).  The oxygen in a rocket's tanks
is burned off on the way to orbit, but the engines have to be carried
all the way, and air-breathing engines weigh a lot more.

And what's the payoff?  The X-30, if it is built, and if it works
perfectly, will just be able to get into orbit with a small payload.
This is about the same as SSTO, at ten times the cost.  Where is the
gain from air-breathing engines?

The fact is, rockets are perfectly good engines for a space launcher.
Rockets are light, powerful, well understood, and work fine at any
speed without needing air.  Oxygen may be heavy, but it is cheap (about
five cents a pound) and compact.  Finally, rocket engines are available
off the shelf, while hypersonic air-breathing engines are still research
projects.  Practical space launchers should use rockets, so SSTO does.

Why No Wings?

With light, powerful engines like rockets, there is no need to land
or take off horizontally on a runway, and no particular reason to.
Runway takeoffs and landing are touchy procedures with little room
for error, which is why a student pilot spends much of his time on
them.  Given adequate power, vertical takeoffs and landings are easier.
In particular, a vertical landing is much more tolerant of error than
a horizontal one, because the pilot can always stop, straighten out
a mistake, and then continue.  Harrier pilots confirm this:  their
comment is "it's easier to stop and then land, than to land and then
try to stop".

What if you don't have adequate power?  Then you are in deep trouble
even if your craft takes off and lands horizontally.  As witness the
El Al crash in Amsterdam recently, even airliners often don't survive
major loss of power at low altitude.  To make a safe horizontal landing,
especially in less-than-ideal weather conditions, you *must* have enough
power to abandon a bad landing approach and try again.  Shuttle-style
gliding landings are dangerous, and airline crews go to great lengths
to avoid them; the Shuttle program, with the nation's best test pilots
doing the flying and no effort spared to help them, has already had
one near-crash in its first fifty flights.  Routine access to space
requires powered landings.

If we are going to rely on powered landings, we must make sure that power
will be available.  Airliners do this by having more than one engine,
and being able to fly with one engine out.  SSTO is designed to survive
a single engine failure at the moment of liftoff, and a second failure
later.  Since (at least) 7/8ths of the takeoff weight of SSTO is fuel,
it will be much lighter at landing than at takeoff.  Given good design,
it will have enough power for landing even if several engines fail.
If SSTO has an engine failure soon after liftoff, it will follow much
the same procedure as an airliner:  it will hover to burn off most of
its fuel (this is about as quick as an airliner's fuel dumping), and
then land, with tanks nearly empty to minimize weight and fire hazard.

Note that in an emergency, vertical landing has one major advantage
over horizontal landing:  horizontal landing requires a runway, preferably
a long one with a favorable wind, while a vertical landing just requires
a small flat spot with no combustible materials nearby.  A few years ago,
a Royal Navy Harrier pilot had a major electronics failure and was unable
to return to his carrier.  He made an emergency landing on the deck of a
Spanish container ship.  The Harrier suffered minor damage; any other
aircraft would have been lost, and the pilot would have had to risk
ejection and recovery from the sea.

Given vertical landing and takeoff, is there any other use for wings?
One:  crossrange capability, the ability to steer to one side during
reentry, so as to land at a point that is not below the orbit track.
The Shuttle has quite a large crossrange capability, 1500 miles.
However, if we examine the history of the Shuttle, we find
that this was a requirement imposed by the
military, to make the Shuttle capable of flying some demanding USAF missions.
A civilian space launcher needs a crossrange capability of, at most, a
few hundred miles, to let it make precision landings at convenient times.
This is easily achieved with a wingless craft:  the Apollo spacecraft
could do it.

Finally, wings are a liability in several important ways.  They are heavy.
They are difficult to protect against reentry heat.  And they make the
vehicle much more susceptible to wind gusts during landing and takeoff
(this is a significant limitation on shuttle launches).

SSTO does not need wings, would suffer by carrying them, and hence does
not have them.

Why Will It Be Cheap And Reliable?

This is a good question.  The Shuttle was supposed to be cheap and
reliable, and is neither.  However, there is reason for hope for SSTO.

The Shuttle's costs come mainly from the tremendous army of people
needed to inspect and refurbish it after each flight.  SSTO should get
by with many fewer.

The basic SSTO concept opens major possibilities for simple, quick
refurbishment.  With no discarded parts, nothing needs to be replaced.
With no separating parts, there is no need to re-assemble anything.
In principle, an SSTO vehicle should be able to "turn around" like
an airliner, with little more than refuelling.

Of course, this is easier said than done.  But there is no real reason
why SSTO should need much more.  Its electronics experience stresses
not much worse than those of an airliner -- certainly no worse than
those of a jet fighter.  Its structure and heatshield, designed to fly
many times, will have sufficient margins that they will not need
inspection and repair after every flight.  Most space-vehicle components
don't inherently need any more attention than airliner components.

The one obvious exception is the engines, which do indeed run at much
higher power levels than airliner engines.  But even here, airliner
principles can be applied:  the way to make engines last a long time
is to run them at less than 100% power.  SSTO engines have it easy in
one respect:  they only have to run for about ten minutes at the start
of the flight and two or three minutes at the end.

Still, the Shuttle engines certainly are not a shining example of low
maintenance and durability.  However, it's important to realize that
the Shuttle engines are not the only reusable rocket engines.  Most
liquid-fuel engines could be re-used, were it not that the launchers
carrying them are thrown away after every flight.  And the durability
record of these other engines -- although limited to test stands -- is
*much* better.  The RL-10 engine, which will be used in DC-X, is rated
to fire for over an hour, in one continuous burn or with up to ten
restarts, with *no* maintenance.  Several other engines have comparable
records.  Conservatively-designed engines are nowhere near as flakey
and troublesome as the Shuttle engines.

Here again, DC-X should soon supply some solid evidence.  Although its
engines and other systems are not the same ones that DC-Y would use,
they should be representative enough to demonstrate rapid, low-effort
refurbishment, and the DC-X program will try to do so.

Airliners typically operate at about three times fuel costs.  The fuel
cost for an SSTO vehicle would be a few dollars per pound of payload.
It may be a bit optimistic to try to apply airline experience to the
first version of a radically new vehicle.  However, even advanced
aircraft typically cost no more than ten times fuel cost.  Even if
SSTO comes nowhere near these predictions, it should still have no
trouble beating existing launchers, which cost several thousand dollars
per pound of payload.

We can look at this another way:  head counts.  Airlines typically have
about 150 people per aircraft, and most of those sell tickets or look
after passengers' needs.  Perhaps a better example is the SR-71, which
is like SSTO in that it was an advanced craft, pushing the frontiers
of technology, operated in quite small numbers.  Although it is hard
to get exact numbers because of secrecy, it appears that USAF SR-71
operations averaged perhaps one flight per day, using perhaps eight
flight-ready aircraft, with a total staff of about 400 people.  That's
50 per aircraft.  If SSTO can operate at such levels -- and there is
every reason to think it can -- it should have no trouble beating
existing launchers, which typically have several thousand people
involved in preparations for each and every launch.  (NASA's Shuttle
ground crew is variously estimated at 6,000-10,000 for a fleet of
four orbiters flying about eight flights a year.)

As for reliability, the crucial reason for thinking that SSTO will do
a lot better than existing launchers is simple:  testing.  It should
be feasible and affordable to test an SSTO launcher as thoroughly as
an aircraft.  This is *vastly* more thorough than any launcher.  The
F-15 fighter flew over 1,500 test flights before it was released for
military service.  No space launcher on Earth has flown that many
times, and the only one that even comes close is an old Soviet design.
It is no wonder that the Shuttle is somewhat unreliable, when it was
declared "operational" after a grand total of four test flights.
By aircraft standards, the Shuttle is still in early testing.  Some
expendable launchers have been declared operational after *two* tests.

Each and every SSTO vehicle can be tested many times before it carries
real payloads.  Moreover, since SSTO can survive most single failures,
it can be tested under extremes of flight conditions, like an aircraft.
For example, unlike Challenger, an SSTO vehicle would launch with
passengers and cargo in freezing temperatures only after multiple
test flights in such conditions.  There will always be surprises when a new
craft is flown in new conditions, but SSTO should encounter -- and
survive -- most of them in test flights.

Conclusion

Although there is reason for some uncertainty about the exact performance
of the first SSTO spacecraft, the basic approach being taken is sensible
and reasonable.  It should work.  The imminent test flights of the DC-X
test craft should resolve most remaining technical concerns.  Nobody can
be sure about costs and reliability until DC-Y is flying, but there is
reason to believe that SSTO should be much better than current launchers.
If the program is carried through to a flying DC-Y prototype in a timely
way, it really could revolutionize spaceflight.

--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
|  [e-mail]     |  nothing undone"                                       |
+----------------------90 DAYS TO FIRST FLIGHT OF DCX-----------------------+

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

Date: Thu, 18 Mar 1993 15:11:03 GMT
From: Matthew Kaiser <[e-mail]>
Subject: SR-71 Maiden Science Flight
Newsgroups: sci.space

is NASA going to run the SR-71 through its paces
and find out what exactly IS its top speed?

matthew
[e-mail]

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

Date: Thu, 18 Mar 93 13:24:51 EST
From: John Roberts <[e-mail]>
Subject: Tidal lock, magnetic field

-From: [e-mail] (Aaron Ray Clements)
-Subject: Re: Moons rotation period question
-Date: 12 Mar 93 05:10:26 GMT
-Organization: California Institute of Technology, Pasadena

-A correction to the above:  the moon's core is not now liquid
-(if it were, the moon would have a significant magnetic field).
-My apologies for the error, and my thanks to Bill Gawne for
-pointing it out to me.

What it tells you is that the moon does not have a liquid, electrically
conductive core with convection currents. Last I heard, it was thought that
there might be partial melting of rock at a certain depth.

It is thought (ref. Science News) that the convection currents in the Earth's
outer core are caused by heat released as the outer core gradually freezes
(or crystallizes under pressure), expanding the inner core. I guess that
means that eventually the Earth won't have a magnetic field either. (This is
a separate issue from possible cooling of the Earth's interior.)

-The continuing lunar tidal locking (I think) is attributable to
-the fact that lunar density is not uniform; this results in the
-center of mass of the moon being offset from the geometrical
-center, creating a gravitational differential across the moon
-that serves the same purpose (but on a much smaller scale).

That alone wouldn't do it - though it does set a minimum angular momentum
to make the moon slip its lock completely - as it is, the moon rocks back
and forth. To permanently establish lock, you need a mechanism to absorb
energy, such as the flexing of rock under tidal influences. I expect this
is also working to circularize the moon's orbit.

John Roberts
[e-mail]

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

Date: Thu, 18 Mar 93 13:48:51 EET
From: [e-mail] (F.Baube[tm])
Subject: Veneraforming (sp?)

fred j mccall 575-3539 <[e-mail]>
>
> [e-mail] (Ata Etemadi)
>
> >-| >VENUS should be given an near Earth-like
> >-| > orbit to become a Born Again Earth
>
> There is the question of where all the excess carbon is going to go.

Terraforming Venus was the subject of an Analog magazine Science Fact
column a couple-three years ago.  The conclusion was pessimistic,
that there is in fact simply too damned much carbon left over.

--
* Fred Baube (tm) Optiplan O.Y. [e-mail]
* "With the present means of long-distance * We live in only one
* mass communication, sprawling isolation  * small room of the
* has proved [an] effective method of      * enormous house of
* keeping a population under control."     * our consciousness
* -- Lewis Mumford, "The City in History"  *  -- William James

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

Date: Thu, 18 Mar 1993 14:49:02 GMT
From: Paul Dietz <[e-mail]>
Subject: Veneraforming (sp?)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] ("F.Baube[tm]") writes:

> Terraforming Venus was the subject of an Analog magazine Science Fact
> column a couple-three years ago.  The conclusion was pessimistic,
> that there is in fact simply too damned much carbon left over.

I thought the Analog article ignored a more promising approach to
terraforming Venus.

Reacting the CO2 with rocks would be a long, slow process; importing
metals to soak up oxygen would also be hard.  It would be better to
remove the CO2, all 4.6e17 tons of it, to space.  This requires a lot
of energy -- about 2.5e28 joules.  The cheapest way to deliver large
amounts of energy is by nuclear explosives.  2.5e28 joules is about
the energy produced by fusing to helium about 50 billion tons of
deuterium.  Since very large bombs hold together longer than small
ones, they should be able to burn more advanced fuels, such as
hydrogen with lithium, boron, or perhaps even carbon, which may be
easier to obtain in large quantities than deuterium, as well as
produce less neutron activation.

The atmosphere would be ejected by simultaneous detonation of many
small bombs.  This would quickly heat and dissociate the atmosphere;
the hot gas, now at higher pressure, would accelerate upwards, cooling
and recombining as it went, over a period on the order of ten minutes.
(This is not to be confused with thermal escape of light molecules
from the top of the atmosphere.)  Sufficient energy input would
accelerate most of the atmosphere to above escape velocity.

    Paul

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

Date: 16 Mar 93 22:43 PST
From: [e-mail]
Subject: what's new at nasa
Newsgroups: sci.space

From: <tom>
Subject: what's new at nasa

From charlie Mon Mar 15 21:00:47 1993
Received: by igc.apc.org (4.1/Revision: 1.70 )
    id AA13681; Mon, 15 Mar 93 21:00:27 PST
Date: Mon, 15 Mar 93 21:00:27 PST
From: Charlie Metzler <charlie>
Message-Id: <[e-mail]>
To: cdplist
Subject: for chuckles
Status: R

>From [e-mail] Sun Mar 14 02:07:33 1993
Received: from ihb.compuserve.com by igc.apc.org (4.1/Revision: 1.69 )
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    id AA26154; Sun, 14 Mar 93 05:07:03 -0500
Date: 14 Mar 93 05:00:20 EST
From: Billy <[e-mail]>
To: Charlie <[e-mail]>
Subject: non-personal but I hope interesting message
Message-Id: <[e-mail]>
Status: RO

SCIENTISTS DISCOVER NEW ELEMENT AT NASA

The heaviest element known to science was recently discovered by NASA
physicists. The element, tentatively named Administratium, has no protons or
electrons and thus has an atomic number of 0. However, it does have one
neutron. 15 assistant neutrons. 70 vice assistant neutrons, and 161 assistant
vice neutrons.  This gives it an atomic mass of 247. These 247 particles are
held together in a nucleus by a force that involves the continuous exchange of
meson-like particles called morons.

Since it has no electrons, Administratium is inert. However, it can be
detected chemically as it impedes every reaction it comes into contact with.
According to the discoverers, a minute amount of Administratium added to one
reaction caused it to take over four days to complete. Without Administratium,
the reaction ordinarily occurred in less than one second.

Administratium has a normal half-life of approximately three years, at which
time it does not actually decay but instead undergoes a reorganization in
which assistant neutrons, vice neutrons, and assistant vice neutrons exchange
places. Studies seem to show the atomic number actually increasing after each
reorganization.

Research indicates that Administratium occurs naturally in the atmosphere. It
tends to concentrate in certain locations such as government agencies, large
corporations and universities. It can usually be found in the newest, best
appointed and best maintained buildings.

Scientists warn that Administratium is known to be toxic, and recommend plenty
of fluids and bed rest after even low levels of exposure.

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

Date: Thu, 18 Mar 1993 13:21:28 GMT
From: Thomas Clarke <[e-mail]>
Subject: What do we do now with Freedom.
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Michael F.
Santangelo) writes:
>
> Problem is, how do you justify throwing away all that money spent
> over the last 10 or so years?  So much has been done already on
> a very specific design for our Space Station.  Doing something else
> in light of this is very hard to swallow.
>
Easy!  Re-charter NASA as a savings and loan and let the Resolution
Trust Corporation take care of the problem!
--
Thomas Clarke
Institute for Simulation and Training, University of Central FL
12424 Research Parkway, Suite 300, Orlando, FL 32826
[phone], FAX: [phone], [e-mail]

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

End of Space Digest Volume 16 : Issue 335
------------------------------