Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT_ZIP/spacedig/V15_1/V15NO175.ZIP/V15NO175

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Date: Tue,  8 Sep 92 05:00:04
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #175
To: Space Digest Readers
Precedence: bulk


Space Digest                Tue,  8 Sep 92       Volume 15 : Issue 175

Today's Topics:
                           Business Travel?
            Inflatable Space Stations - Why Not ? (2 msgs)
         Is NASA really planning to Terraform Mars? (3 msgs)
                   Mars Observer Update - 09/04/92
                    Pluto Direct/ options (3 msgs)
                         Relativity (2 msgs)
                        Space markets (2 msgs)
                  THANKS on shuttle traking program
                            Venus orbiters

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

Date: 8 Sep 92 02:13:28 GMT
From: Byron Meadows <[e-mail]>
Subject: Business Travel?
Newsgroups: sci.space,rec.travel,soc.misc

In article <[e-mail]> [e-mail] (Matt Baney) writes:
>
>I'm trying to get some information about how other companies treat
>employees traveling on company business; so I have a couple
>questions:
>
>Does the Frequent-Flyer mileage earned for company travel go to the
>employee for his/her private use or is it retained by the company?


 Working for the gov't, we aren't suppose to use the FF mileage for ourselves
 but the system is not set up for the gov't to keep track of them or use them.

>
>What type of rental car do you get?
>  Cheapest possible (  )
>  What ever the traveler desires (  )
>  ??
>
 A mid-size is the standard rental.  Usually a Ford Tempo(yuch!!) Sometimes
 if your lucky a Ford Probe or Mustang--you get the idea.


>What is the policy for eating/living expenses when travelling??
>
>  (  ) Flat rate per diem and you can spend it however you like
>       How much per day $(_____)
>
>  (  ) Actuals, company pays whatever amounts the employee acrues during
>  the business trip.  receipts required yes( )  no( ),
>  daily maximum no( )   yes( )-how much $( )
>
>  Any restrictions on what is allowed/ paid for, etc??


NASA uses the per diem system which is broken down into 2 parts. We receive
an allowance for lodging that is not to exceed a predetermined amount
depending on the cost of living for the area--higher in places like NY or
DC lower in less urban areas.  Any cost above the maximum allowable comes out
of your own pocket.  If you stay in a hotel that is below the maximum you
only receive that amount (you don't get to keep the rest).

We also receive an allowance for Meal and Incidental Expenses (M&IE). This
is also based on the cost of living for the area.  However, whatever of this
amount we don't spend we keep.


>Are there any restrictions/policies about when trips should be
>scheduled, ie. do you have to fly on your own time, or is travel
>done on company time, or whenever is convienient??


Travel is scheduled based on when the work dictates we need to be there.
Unfortunately, as we have complained before, if we travel on the weekend
we are on our own time unless we report to work directly after arriving at
our destination.

>  ----------------------------------------------
>
>  Just a few questions I was curious about??  Anyone out there have
>  any thoughts/comments
>
>
>
Hope this helps,
Byron

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

Date: 7 Sep 92 13:51:47 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: Inflatable Space Stations - Why Not ?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Russell Katz) writes:

>Any of you experts out there have an answer as to why NASA doesn't use the
>tanks as at least a temporary habitation?

Check out the External Tank Study performed by Space Studies Institute
a few years ago. They cover ET uses ranging from space stations to
fuel recovery.

   Allen

--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "If they can put a man on the Moon, why can't they     |
|  [e-mail]     |  put a man on the Moon?"                               |
+----------------------228 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: Thu, 3 Sep 1992 13:41:58 GMT
From: "Michael K. Heney" <[e-mail]>
Subject: Inflatable Space Stations - Why Not ?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Russell Katz) writes:
>This is a bit related to the topic...I think.
>
>I have read in several sf stories about using the shuttle main tanks as
>modules for space habitats...just having the shuttle carry the tank with it
>into orbit.  Some authors stated that it would not take any extra fuel(??)
>to do so.
>
>Any of you experts out there have an answer as to why NASA doesn't use the
>tanks as at least a temporary habitation?
>
I hardly qualify as an expert, but there are several very good reasons why
NASA doesn't use the tanks.

1)  They tend to come down pretty quickly.  Empty, they're very low-density
structures, which causes their orbits to decay fairly quickly.  Note that
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.  The tank *is* set tumbling by venting
LOX thru the top to produce a predictable cross-section and horrible
drag characteristics, while the orbiter keeps a minimum drag attitude.

2) There's residual LH2 and LOX in the tanks - close to 5,000 lbs LH2,
if I remember correctly.  They don't run the tanks dry because the
engines would "belch" as fuel flow became erratic the last few seconds -
not healthy for the engines.  Mission planners don't really want to
carry that stuff around on the orbiter's belly any more than they have to -
a valve-closing problem or just plain leakage could allow both LH2 and LOX
to vent (the tank is built to be a throwaway; not space-certified orbital
hardware), so they want to drop it as soon as possible.

3) The foam insulation has trapped gasses in it (it was foamed on
in the atmosphere, after all), and there are concerns that it could
"pop" like popcorn over time in vacuum, contributing a fair amount of debris
in the same orbit as the orbiters like to use.  There have been suggestions
to wrap the tank in beta cloth or something similar once on orbit to
contain this.

4) The level of on-orbit operations needed to convert an ET are non-trivial.
There *is* an access "hatch" on the bottom of the LH2 tank - 3 feet in
diameter and bolted on *very* securely.  Martin Marietta (henceforth MM)
has determined that a spacesuited astronaut *could* get through the
hatch - it's *barely* big enough.  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.  Yes, it sounds like fun (!), I'd go and do it in
a minute, but it's more work and money than NASA can reasonably be expected
to put out when it's easier and SAFER to build the stuff on the ground and
boost it to orbit with minimal EVA required.

MM has (at least as of 1989) an office which dealt with ET on-orbit
applications.  The US gov't apparently in 1988 or 1989 said that for
a 5-year period, anyone who wanted an ET could have it *free* after launch
provided they could assure controlled re-entry or maintenance of a
stable orbit AND dealt with the insulation-popcorn concerns.  I
recall that it would require an extra 1800 lbs of OMS fuel for the
OMS-2 burn to carry the ET all the way to LEO; this may fall within
the "management reserve" allocated on a mission, but this reserve is for
contingincies (e.g., the Intelsat rescue - damn near ran the tanks dry
in the nose because of 3 instead of 1 rendezvous (rendezvouses?)
(and very fuel-efficient flying at that).

Bottom line - yeah, I'd like to see all that metal hauled up to
orbit, too, even as just an orbital scrap yard.  After all, we *will*
at some point be able to use tons of metal in oribital apps sooner
or later.  There's been talk of a "beam builder" crunching the tanks into
tiny pieces, melting them, and extruding truss members, for example.
But it's not gonna happen this year, or next.
--
Mike Heney                |                                  |  Reach for the
[e-mail]   |     * Will Work for Money *      |  Stars, eh?
Kensington, MD (near DC)  |                                  |

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

Date: 7 Sep 92 23:55:32 GMT
From: "Thomas H. Kunich" <[e-mail]>
Subject: Is NASA really planning to Terraform Mars?
Newsgroups: sci.space

(I am reposting this at request)

There have been suggestions of terraforming Mars, perhaps
even Venus. There may even be other planets or satellites
in the solar system that lend themselves to being improved
upon by man.

Well, I have a suggestion.

We can talk of sending manned flights to Mars, but we do
not have the technology yet, nor the budget for such a
prolonged and possibly ineffective space flight. Maybe we
haven't learned from recent attempts to mass produce
science, but miracle breakthoughs simply don't happen on
schedule if ever. So talk about terraforming with unknown
technologies is premature to say the least.

Yet we do have the capability of terraforming Mars or the
very least modifying Mars to support life of some sort. The
same could probably be said of Venus and other places.

If the Gaia principle really exists, and I find the
principle attractive, then we can let life do it's own work
on these planets.

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. 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.

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.

Oh, maybe the results won't look like our ideas of life. If
Gaia lives on Venus I am sure that she is a Venusian Gaia.
We would find her, perhaps, a little hot blooded for our
tastes. The Martian Gaia might be more to our liking but
then again who is to say? So too for the Titan Gaia.

Would the Gaia principle work? I, for one, think that it
would. In any case the results would be a satisfying and
informative experiment that would cost pennies along the
lines of space travel these days.

Of course it would be unethical to interfere with any life
there may be already there. So considerable exploration
would be necessary to give a moral basis for such a
project. But consider this:  Should man never be able to
budge from this planet in earnest we will have had our
moment of godhood and brought life to pass. And perhaps,
after all, that is the true meaning of life.

(This is a new posting on the subject)

A couple of comments have come my way in regards to the
Gaia principle. Maybe I ought to make myself lucid.

My direct quote regarding Gaia was, "If the Gaia principle
really exists, and I find the principle attractive, ~ ".

I did not say, nor do I maintain, that there is anything of
a supernatural nature about Gaia. Nor does it's original
author to my knowledge, which is admittedly slight.

Scientists can find no problem understanding nuclear
physics, with it's myriad complex intertwining of actions
and interactions. Physicists can talk for days, weeks or
even months on end about how each step leads to the next
which leads to the next in a steady flow of cause and
effect that weaves a pattern of infinite complexity and
beauty from simple original concepts.

Geologists can trace the development of the earth's mantle
over the millennia. The sedimentation and metamorphosis of
one type of stone to the next. All with a precise line that
natural laws predict with clarity at least in retrospect.

Others can trace the beginnings of life on this planet,
step by step, through eons of time. Showing how each
evolution follows the previous and theorizing about the
ecological changes that presented themselves to produce
these changes. Cause and effect, cause and effect.

Gaia, as I understand it, isn't a direct line that supposes
that what we have now is what was meant to occur from the
beginning. Gaia is the chain of events whereby life
actually does change the world around it. After all, isn't
it a little obscure to say that man is destroying his
environment and then to imply that he is the only life form
capable of doing so? I find it astonishing that intelligent
people could _not_ find the Gaia principle interesting!

No, as I say, I find the principle of Gaia attractive. I
find that it is a theory that can be tested. I have
suggested a test of that theory that can be run for a
miniscule fraction of what terraforming projects of other
types would cost. Something that requires very little in
the way of new technology. And something that could result
in the bringing of life to other lifeless worlds in this
universe.

And in the final analysis this may be the only way man can
spread life off of this small planet.

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

Date: Tue, 8 Sep 1992 00:43:18 GMT
From: Paul Dietz <[e-mail]>
Subject: Is NASA really planning to Terraform Mars?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Thomas H. Kunich) writes:
>(I am reposting this at request)
>
>There have been suggestions of terraforming Mars, perhaps
>even Venus. There may even be other planets or satellites
>in the solar system that lend themselves to being improved
>upon by man.
...>
>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. 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.
>
>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.


Pseudoscience about Gaia notwithstanding, this doesn't work.

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).

As for Venus: the clouds there are concentrated sulfuric acid.  Should
anything be able to survive there, which is doubtful, it could not
terraform Venus into anything remotely habitable to humans, as the
primary problem is how to get rid of the atmosphere.  Converting it to
oxygen and biomass doesn't work; there is just too much oxygen there.

    Paul F. Dietz
    [e-mail]

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

Date: Tue, 8 Sep 1992 02:52:40 GMT
From: David Knapp <[e-mail]>
Subject: Is NASA really planning to Terraform Mars?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Paul Dietz) writes:
>In article <[e-mail]> [e-mail] (Thomas H. Kunich) writes:
>>(I am reposting this at request)
>>
>>There have been suggestions of terraforming Mars, perhaps
>>even Venus. There may even be other planets or satellites
>>in the solar system that lend themselves to being improved
>>upon by man.
>...>
>>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.


Thomas, would you expound on which bacteria or fungi can exist in a hot sulfuric
acid/sulfur dioxide environment?

>> These life-forms
>>are small, light and quite capable of being transported in
>>rather massive quantities to these planets by presently
>>possessed technology. 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.
>>
>>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.

Like his ashes, maybe. No, let's send Dan Quayle! He says that since there
are canals on Mars, there's water and if there's water, then there's air
and if there's air we can breathe.  I suggest we send Dan Quayle to Mars
so he can breathe there.


>Pseudoscience about Gaia notwithstanding, this doesn't work.
>
>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 think the most reasonable proposals involved life forms in the *regolith*,
not at the surface.  There is a great deal of evidence for abundant water
in the regolith and there are places there where liquid water can exist.


>As for Venus: the clouds there are concentrated sulfuric acid.  Should
>anything be able to survive there, which is doubtful, it could not
>terraform Venus into anything remotely habitable to humans, as the
>primary problem is how to get rid of the atmosphere.  Converting it to
>oxygen and biomass doesn't work; there is just too much oxygen there.
>
>    Paul F. Dietz
>    [e-mail]

Really the most interesting aspect of terraforming either planet is the amusing
speculation.



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

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

Date: Mon, 7 Sep 1992 19:00:52 GMT
From: Steve Collins <[e-mail]>
Subject: Mars Observer Update - 09/04/92
Newsgroups: sci.space,sci.astro

Boy it will be nice when Mars Observer is in space where it's safe...
                             steve collins MO-SCT

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

Date: 7 Sep 92 17:32:53 GMT
From: Pat <[e-mail]>
Subject: Pluto Direct/ options
Newsgroups: sci.space

I saw parts of the pluto direct flyby talk by staehle from JPL.
they are talking of sending a 1-200 kg orbiter to pluto.

Did they consider using energia?  most of the charts I remember
were using titan or delta class launchers?

I was thinking an energia would allow a bigger bird or possibility of
more thrust to slow down the encounter.

Does anyone know if that's an idea, or do they want to hold costs down
to $150 million?

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

Date: Tue, 8 Sep 1992 04:37:00 GMT
From: "Horowitz, Irwin Kenneth" <[e-mail]>
Subject: Pluto Direct/ options
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Pat) writes...
>
>
>I saw parts of the pluto direct flyby talk by staehle from JPL.
>they are talking of sending a 1-200 kg orbiter to pluto.
>
>Did they consider using energia?  most of the charts I remember
>were using titan or delta class launchers?
>
>I was thinking an energia would allow a bigger bird or possibility of
>more thrust to slow down the encounter.
>
>Does anyone know if that's an idea, or do they want to hold costs down
>to $150 million?
>
I was also at Staehle's talk at the WSC and since I have some background
on this mission, I will attempt to describe it.

The plan is to send a pair of spacecraft to Pluto on a direct trajectory.
The mass of each craft is currently 164kg.  They are talking about launch
on either a Atlas or a Proton (the Atlas would allow a slightly higher
payload mass).  The current launch date is 1998, with an 8 year flight time
to Pluto.  Each craft will be able to carry out 4 primary science experiments:
Optical imaging using a CCD camera, UV spectroscopy, an IR payload and radio
science using the main antenna.  The mass allocation for the three instruments
is only a few kgs.  Power will be provided by an RTG.

This mission is an example of the new "cheaper, faster, better" attitude that
Goldin is trying to bring to NASA.  The budget is only $400M for the entire
mission, and they are real serious about sticking to that figure.  Getting
the craft off the ground in six years is much faster than other big projects
that NASA has undertaken in recent years (JPL is learning a hard lesson from
CRAF/Cassini).  As for better, well that will have to wait until they get out
to Pluto to determine :-).  The primary drivers in the past were performance,
schedule, cost.  For this mission, these have been reversed, so that cost is
the primary consideration, and they are going to overlook a lot of potentially
interesting science in an attempt to avoid the pitfalls of many other projects,
that just grew too big b/c everyone wanted a piece of the pie.  In addition,
Staehle is committed to bringing a large number of students into the project,
and primarily those students will come from local SEDS chapters here in LA.
(SEDS==Students for the Exploration and Development of Space).  Indeed, if
you had the chance to see the mockup of the flyby craft in the exhibition hall
(in the main NASA area in front), that was built by one of the members of
Caltech SEDS as his summer project.
-------------------------------------------------------------------------------
Irwin Horowitz                        |
Astronomy Department                  |"Whoever heard of a female astronomer?"
California Institute of Technology    |--Charlene Sinclair, "Dinosaurs"
[e-mail]                |
[e-mail]                 |
-------------------------------------------------------------------------------

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

Date: 8 Sep 92 04:51:02 GMT
From: Josh 'K' Hopkins <[e-mail]>
Subject: Pluto Direct/ options
Newsgroups: sci.space

[e-mail] (Pat) writes:

>I saw parts of the pluto direct flyby talk by staehle from JPL.
>they are talking of sending a 1-200 kg orbiter to pluto.

Actually, they'd like to send two so that they can image both sides of the
planet.

>Did they consider using energia?  most of the charts I remember
>were using titan or delta class launchers?

The two options are Titan IV and Proton (which is a Soviet rocket with a
smaller fan club than Energia).  They would prefer to use a Proton because of
pricing, but they're unsure of the performance of Proton upper stages.

>I was thinking an energia would allow a bigger bird or possibility of
>more thrust to slow down the encounter.

The problem is that a bigger probe is much more expensive, and you can't
really slow down the encounter much without extending the trip time greatly.

--
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: 7 Sep 92 12:53:50 GMT
From: David Meiklejohn <[e-mail]>
Subject: Relativity
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Alan Barclay) writes:
>#4300029 from John Roberts
>
>I always thought I had a good handle on the basics of relativity.

Well, we all like to think we do, don't we?  :-)

>Can you have a look at this for me, and tell me what you think?

OK, I'm just a humble engineer, but let's see...

>A Thought experiment:
>
>Star A is four light years from star B.  A spaceship leaves earth
>and accelerates to .9 C and ceases acceleration when it passes
>Star A.  An observer inside the moving frame notes the length of
>subjective time passing.  When the ship passes star B, the observer
>inside the frame has only experienced 1.95 subjective years.  For him,
>he traversed four light years in only 1.95 years.  A subjective speed
>of 2.05 C.

 [ mathematics deleted ]

>However, if he were to use instruments to determine his velocity
>relative to the frame of reference, his velocity would remain .9 C.
>
>The only flaw I can see in this is if my observer's velocity somehow
>changes the timing of his observations of incidence with Star A or B.

No, his time measured is 1.95 years, as you say.  What you're missing is that
there is no favoured frame of reference, given that he's not accelerating.
Therefore, as far as our astronaut is concerned, he's stationary, and the
universe is rushing by at 0.9 c.  Now, when you move, the only relatavistic
effect isn't time dilation.  You gain mass, and your metrics contract in the
direction of motion.  This last effect means that the observer measures the
distance between the stars as 2.17 ly.  As far as he's concerned, he's taken
1.95 years to travel between two objects 2.17 ly apart, so he's measured his
speed as 0.9 c.

So, it all works out.

>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?

I don't see why not.  To continue to accelerate, the spaceship needs energy.
An increasing proportion of this energy is converted into mass, rather than
velocity, as c is approached.  The real question is, where did the energy
come from?  Assume that the spaceship used a perfect antimatter drive, so
that all of the mass of it's fuel is converted into energy and is used for
acceleration.  In effect, your just turning mass into mass as c is approached.
Nothing is gained, except maybe some compression, depending on how the ship
is arranged.  If that's the case, it would have to be close to gravitational
collapse before it started.

Maybe energy is fed from outside as it travels.  Sounds dubious to me.

>Not knowing the more complex math of relativity, I have no way of
>proving it to myself.  But I wonder if time dilation due to velocity
>(and the gravitation itself?) would put the singularity at the end of
>an asymptotic curve, like v=1.0C, completely unachievable.

I'm hardly an expert on black holes, but you don't need infinite density to
initiate collapse, which is what your v=c would imply.


--

David Meiklejohn                  | Internet : [e-mail]
Computer Systems Officer, QDPI    | Fax      : [phone]
Mareeba, Australia                | Voice    : [phone]

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

Date: Mon,  7 Sep 1992 11:15:49 -0400
From: Samuel John Kass <[e-mail]>
Subject: Relativity
Newsgroups: sci.space

>>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?
>I don't see why not.  To continue to accelerate, the spaceship needs energy.

Could it?  I'm no expert either, but I thought that to get collapse,
parts of the object had to be pulling against each other.  Since the
ENTIRE spaceship is accelerating, from the frame of reference of the
spaceship, wouldn't it be 'normal' mass?  Of course, from the frame of
reference of a 'stationary' observer, the spaceship will have sqashed
itself so flat that it should have fused anyway.  Since, by general
relativity, there is no preferred frame of reference, why would the
Earth, then, not collapse into a black hole, just because such a thing
is possible.  (ie. Compared to the frame of reference of something else,
the Earth has enough mass to collapse.)  For example, there may be an
object in the universe travelling at such speeds that, to it, the Earth
should have collapsed into a black hole.  But we're not a black hole. (I
don't think.)

>>acceleration.  In effect, your just turning mass into mass as c is
approached.
>>Nothing is gained, except maybe some compression, depending on how the ship
>>is arranged.  If that's the case, it would have to be close to gravitational
>>collapse before it started.

it _IS_ possible to accelerate things without having the mass on board.
Could we create a "black hole factory" with a long enough linear
accelerator?

   --Sam Kass

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

Date: 7 Sep 92 13:03:32 GMT
From: Gary Coffman <ke4zv!gary>
Subject: Space markets
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Nick Szabo) writes:
>
>There is no need for tiny-market HLVs; commerce can share launchers with the
>military and civilian space agencies.  The civilian agencies should be
>following the lead of military and commerce, instead of living in their
>own world building space stations, then building HLVs to support them,
>none of it relevent to the commercial market.

It's not the charter of the civilian space agency to follow in anyone's
wake, certainly not the commercial sector. The agency is supposed to
do space R&D that no commercial entity will attempt because it's too
risky or too costly. The agency is supposed to break new ground, not
ride the coattails of the military or commerce. The current commercial
market is irrelevant to the agency's mission.

Gary

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

Date: 7 Sep 92 13:40:59 GMT
From: Gary Coffman <ke4zv!gary>
Subject: Space markets
Newsgroups: sci.space

In article <[e-mail]> [e-mail] writes:
>
>Look at the troubles Iridium is having raising their capital for a commercial
>venture  and they have a great business plan with a high rate of return. The
>prime problem they have is that it is new tech and no one has sufficient
>intestinal fortitude to bankroll them, therefore they are spreading the risk
>and lowering their own returns by going into partnerships with many companies.
>This has delayed the program for at least two years.

Iridium has tremendous problems, but lack of guts isn't one of them.
The two biggest problems faced by the system are regulatory issues
on a global scale, and what to do if the system actually attracts
a large user base. As terrestrial cellular providers are discovering,
the big problem is achieving *small* enough cells to prevent the
user base from overloading the system. A small satellite can't
carry a big enough array to shrink cell sizes as demand increases.
Users will quickly abandon a system where they almost always get
a busy. Yet without a large user base the system can't turn a
profit.

They can try to limit the user base by charging $100 a minute for
service, but there are only so many drug lords in the third world,
and they've installed their own terrestrial cellular service.
Iridium can't serve 4/5 of the world's population. All it can be
is a plaything of the very rich, and the very rich are intolerant
of limits. Investors aren't stupid. They can count very well. Iridium
isn't risky because it uses advanced technology, it's risky because
it's technology isn't advanced enough to serve it's potential market.

Many companies have failed because they were too successful in
creating a market for their products while being unable to
deliver on their marketing promises when the scale got too
big. Iridium's main danger is not that it will fail, but that
it will succeed too well.

Gary

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

Date: 7 Sep 92 22:23:35 GMT
From: Matthew Sheppard <[e-mail]>
Subject: THANKS on shuttle traking program
Newsgroups: sci.space

Thanks for all the responses on the shuttle traking program.

I found it at ames.arc.nasa.gov , and it was called stsorbit.arc.

Thanks again.

--
| Matthew Sheppard  CLARKSON UNIVERSITY  [e-mail] |
| I'd rather have a bottle in front of me than a frontal lobotomy.ANoN |
| I don't want a pickle. DoD#477 TEP#477 RIDE FREE (8^]..etcetera..    |

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Date: Sun, 6 Sep 1992 18:59:46 GMT
From: Pat <[e-mail]>
Subject: Venus orbiters
Newsgroups: sci.space

In article <[e-mail]> [e-mail] writes:
>aerobraking next year for Cycle 5.  Of course, this is assuming that Magellan
>isn't turned off at the end of Cycle 4.  Magellan is in Cycle 3 right now with
>Cycle 4 due to start on September 14.  Each cycle lasts 243 days, or one
>Venusian day.
>     ___    _____     ___


Rumour has it that COngress and certain unnamed NASA Brass want to keep magellan
alive for as long as possible.
The DDTE for Magellan was $600 million (appx) so why not burn 60 million
more to get better gravity data..

also word is that small light probes are hot for funding in the near future.
cheap fast missions are being experimented with to avoid cost problems
with  heavy big birds.

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End of Space Digest Volume 15 : Issue 175
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