Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V15_4/V15NO450.TXT

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Date: Tue, 24 Nov 92 05:00:03
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #450
To: Space Digest Readers
Precedence: bulk


Space Digest                Tue, 24 Nov 92       Volume 15 : Issue 450

Today's Topics:
                              Databases
                         GE Aerospace status?
                                 ISU
   Pete Conrad (was Re: SSTO Viability (was: Shuttle replacement))
                       Pumpless Liquid Rocket?
                         ROTATION OF THE MOON
                           SATELLITE PHOTO
                SGI Space Simulator Version 1.0 (long)
                          Shuttle computers
                     Shuttle replacement (5 msgs)
                            Solar sailing
          SSTO Viability (was: Shuttle replacement) (2 msgs)

    Welcome to the Space Digest!!  Please send your messages to
    "[e-mail]", and (un)subscription requests of the form
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    (THENET), or [e-mail] (Internet).
----------------------------------------------------------------------

Date: 23 Nov 92 10:34:38 GMT
From: Thomas Enblom <[e-mail]>
Subject: Databases
Newsgroups: sci.space

Is there anybody that could provide me with a list of databases that
contain information about spaceflight (shuttle, pioneer, astronomy ...anything).

I suppose there are databases at JPL and Goddard etc.

The databases must be able to communicate through email because I don't
have access to anonymous FTP.

If you could suggest a database, please also enclose instructions how to use it.

(I already have access to [e-mail])

Thank you.

================================================================================
Ericsson Telecom, Stockholm, Sweden

Thomas Enblom, just another employee.

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

Date: 23 Nov 92 15:14:35 GMT
From: Steven Back <[e-mail]>
Subject: GE Aerospace status?
Newsgroups: sci.space

There have been a large number of rumors running around about a
change in the status of GE Aerospace.

So what's the real story?

Thanks
Steven Back
[e-mail]

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

Date: 23 Nov 92 13:15:06 GMT
From: Scott A Koester <[e-mail]>
Subject: ISU
Newsgroups: sci.space

   I am highly interested in obtaining information about the International
Space University, anyone know who I can contact and where? Valid email
addresses would work also.  Give me responses in email please, i would greatly
appreciate it. Thanks everyone....



Scott Koester

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

Date: 23 Nov 92 06:52:03 GMT
From: Bill Higgins-- Beam Jockey <[e-mail]>
Subject: Pete Conrad (was Re: SSTO Viability (was: Shuttle replacement))
Newsgroups: sci.space.shuttle,sci.space

In article <[e-mail]>, [e-mail] (Allen W. Sherzer) writes:
> In article <[e-mail]> [e-mail] (Rich Kolker) writes:
>
>>Simulator testing for the DC-X/Y/1 pilots is underway.  As you know, DC-X
>>will be flown remotely, DC-Y will be crew-capable.  Among the pilots trainingh
>>is Pete Conrad.  If that name sounds familiar....it should!
>     ^^^^^^^^^^^^^
>
> It sure does! He was one of the actors on the made-for-tv movie Plymouth.
>
I think he was also a model for some of the works of painter Alan Bean.

     O~~*           /_) ' / /   /_/ '  ,   ,  ' ,_  _           \|/
   - ~ -~~~~~~~~~~~/_) / / /   / / / (_) (_) / / / _\~~~~~~~~~~~zap!
 /       \                          (_) (_)                    / | \
 |       |     Bill Higgins   Fermi National Accelerator Laboratory
 \       /     Bitnet:     [e-mail]
   -   -       Internet:  [e-mail]
     ~         SPAN/Hepnet:      43011::HIGGINS

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

Date: 23 Nov 92 16:08:59 GMT
From: Thomas Clarke <[e-mail]>
Subject: Pumpless Liquid Rocket?
Newsgroups: sci.space

I was thinking about the problem
of pumping in a liquid fuel rocket
and wondered if there might be an
alternative to fragile turbo pumps
or heavy pressurized tanks.

Consider:

 ______
|      |
|      |
|      |  Tankage
|      |  Depth D
|      |   Area A
 \    /
  \  /
   ||
   ||
   ||       Connecting
   ||      Pipe
   ||    Length L
   ||
  _||_
 |    |   Thrust Chamber
  \  /     Area T
  /  \
 /    \

That is connect the tankage to the rocket engine
with a long pipe.  When accelerating (or at
rest in a gravity field) hydrostatic pressure
at bottom of pipe can be fairly high - like a
water tower.  I think if L/D > A/T, then
the pressure caused by the acceleration should
be sufficient to operate the engine with
enough thrust to cause the acceleration to ...

No pumps!  Startup could be a problem though,
especially in free fall.  I envision sort
of a flying water tower with the long pipe
perhaps stiffened by guy wires as in a
sailboat mast.

Has this ever been tried?

--
Thomas Clarke
Institute for Simulation and Training, University of Central FL
12424 Research Parkway, Suite 300, Orlando, FL 32826
[phone], FAX: [phone], [e-mail]

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

Date: 23 Nov 92 19:00:07 GMT
From: David Ray <[e-mail]>
Subject: ROTATION OF THE MOON
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (paul.h.nelson) writes:
>Since the moon is gradually receding from the earth, due to tidal effects,
>can we extrapolate backwards in time and postulate how close it has been
>to the earth and when?

Scientists have been grappling with this issue for years. It is one of the
scientific paradoxes of our lifetime.

The moon's orbit is also inclined with respect to the earth's equator, and
the orbit would have been *more* eccentric in the past -- tidal effects
are making it more circular. If you extrapolate backwards, the eccentricity
of orbit would have become impossible for any orbit to exist more than
a few hunderd million years ago. Yet, We have confirmed the Moon's age of
well over a billion years from carbon dating. So, either the moon was "captured"
into Earth's orbit well after its formation, or its orbit was significantly
perturbed after it was in Earth orbit.

The degree of tidal dissipation in the past is another large uncertainty.
We can measure the slowdown rate now, but scientists believe that the tidal
dissipation rate was much different in the past, particularly during the
ice ages. Virtually all tidal dissipation of the Moon's orbit comes from the
ocean. During ice ages, there was less ocean, more ice. The issue of "resonant"
frequency of some parts of the ocean is another issue. If only a small part
of the ocean constitutes most of the tidal dissip[ation, the effects of changes
in the tidal dissipation due to changes in ocean might not be as simple as
just the quantity of available ocean mass.

Another hitch is the lack of iron in the moon. The amount of iron tells us if
the moon came out of (or was formed near) the Earth in the formation stages
of the solar system. Normally, a body the size of the Moon should have an
iron core making up about the same % of total mass as the Earth (say within
a factor of three). But our data indicates it is almost an order of magnitude
less. So, did it not form from the same primordial mass? They can't answer
that one, either.

The only single theory that makes sense is that:
1. The earth formed from a primordial mass with a normal amount of iron
2. There was a gravatational pertubation very close to the earth at a very
   specific geologic time, after most of the iron in the earth settled to the
   center. The pertubation expelled material out of only the outer portions of
   the earth, which were depleted in iron.
3. The Moon formed from the material expelled from the pertubation, and has
   orbited the Earth ever since.
4. There has been at least one gravatational pertubation to the moon's orbit
   after it was completely formed, knocking it into its irregular orbit that
   we now observe.

dave


>
>ALso, can we pick a lower bound earth orbit, where the moon would have broken
>up and fallen into the earth, and use that as an UPPER bound for the
>age of the earth-moon system?

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

Date: 23 Nov 92 18:29:07 GMT
From: David Ray <[e-mail]>
Subject: SATELLITE PHOTO
Newsgroups: sci.space

>In article <[e-mail]> [e-mail] (IEGS000) writes:
>>COULD SOMEONE HELP ME: SUPPOSE A HURRICANE JUST BLEW IN! WHERE CAN I
>>FIND A SATELLITE PHOTOS OF IT'S PROGRESS?

If you have internet access during the storm, you can FTP weather satellite
photos of N. America which are updated every hour. The images are in GIF
format so you need appropriate viewing software (shareware GIF viewers
are available for PC's and Macs.)

Do this:                    by typing this:

FTP to the site:            ftp 128.174.5.98
login as:                   anonymous
change directories:         cd WX
set binary transfer mode:   binary
list available GOES images: ls CV*
get the desired file:       get CVmmddhh.GIF
end ftp session:            bye

The image files are in the form CVmmddhh.GIF where mmddhh is the month, day
of month, andhour in Greenwich standard time. (For example, CV112316.GIF)
These files are about 90k and are kept for a day or two. There are also
higher-resolution versions of the same files, about 350k, which they only
keep the latest version of due to hard disk limitations -- this file is
named CVIS.GIF.

Finally, a non-smart-ass answer.

Dave

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

Date: 23 Nov 92 12:32:29 GMT
From: [e-mail]
Subject: SGI Space Simulator Version 1.0 (long)
Newsgroups: rec.aviation.simulators,sci.astro,sci.space

SGI Space Simulator Version 1.0

I just had the chance to play with one of the coolest
simulations/machines I have ever seen.

We have a Crimson SGI (100K$ class) on site and there is
GL demo program called space or the
SGI Space Simulator Version 1.0.

It's a  simulation of the Solar System and the Milky Way galaxy
with certain artistic liberties.

It's like something you see on Nova or other PBS shows when
they describe planetary orbits, etc.  Anyone who is interested
in space/astronautics can spend several hours playing with this
program exploring the solar system and galaxy.  I highly recommend
everyone to seek out one of these machines and see this program.
I am sure it comes on the lower class SGI machines also, but the
speed of the Crimson will "knock your socks off".

It starts by placing you in our solar system.  The orbits of the
planets are displayed (green) along with the names.  Standard aircraft
yoke controls are driven by the mouse.  (Rolls are difficult though.)

You can navigate the system by controlling your velocity/direction.
As you approach a planet, you will begin to see the orbit paths
of the moons in blue with names.  You can turn off the orbit paths
and object labels and see graphics of the planets/moons.  As you
approach even closer, the images get clearer and more defined.  Saturn is
spectacular during a flyby, like watching Star Trek, etc.

It appears that satellite Earth color data and planetary color data
have been incorporated into the database.  If you approach, say earth,
the terrain goes through 4 to 5 levels of increased resolution.  With
planets with atmospheres, the sky changes color and the stars fade
from view.  You can position yourself to observe ecplise events.

I am not a space scientist and don't know what the accuracy is of
this simulation, but it was a very fascinating experience.  Very
educational, now I know what the surface of the moon of Pluto looks
like.  It's an image of the software engineer who wrote this program.
:)  While visiting other landscapes I half expected to see a
billboard for SGI.

By changing time, you can observe the motion of planets and moons in
their orbits.  Zodiac and star names can be displayed.  You can
explore other star systems and observe other planetary systems.
(Documented fact starts to break down here, I am sure, but it makes it
interesting.)  There is even a Dysan type system called "Ring World".  You
can accelerate beyond the local systems out to the bounds of the galaxy.
Stars are replaced with an image of the galaxy.  Going further
into inter-galactic areas you can easily get lost and not find your
way back.  An autopilot function can return you to the familar
Sol system.

Here are the commands the operate the program:

 MOUSE CONTROLS
    left   : accelerates
    middle : brakes
    right  : pan/rotate toggle

    left+right   : face nearest moon
    middle+right : face nearest planet
    left+middle  : face nearest star

    (Use these with the autopilot engaged!  Really cool.)

 KEY CONTROLS
 Esc   : quit
 Shift : defeat mouse controls (for menu)
 Ctrl  : disconnect view vector from velocity vector
     a : autopilot
     b : single buffer mode (< 24bits) (left mouse is trigger)
     h : on screen help toggle
     i : moons/orbits toggle
     l : reshade polyplanet every frame
     n : star name toggle
     o : planets/orbits toggle
     q : control panel toggle
     r : decelerates time by 10
     s : stellar system statistics
     t : accelerates time by 10
     v : reverse velocity
     x : text display toggle
     y : time reset
     z : display constellation boundaries
     - : time direction toggle
     up   arrow : increase tesselation level (max: 5)
     down arrow : decrease tesselation level (min: 0)
     PrintScrn  : snap rgb image and quit

 TEXT COLOR CODES
    red   : in interplanetary space
    blue  : in interstellar space
    yellow: in intergalactic space
    green : currently being eclipsed

Satellite Earth color data provided by
TOM VAN SANT and the GEOSPHERE PROJECT
With assistance from NOAA, NASA, EYES ON EARTH
Technical Direction Lloyd van Warren, Leo Blume, Jim Knighton
Source data derived from NOAA/TIROS-N Series Satellites
All rights reserved by Tom Van Sant, Inc.
146 Entrada Drive, Santa Monica, CA 90402
310-459-4342

This program seems to be a sales demo for SGI, but this is
the kind of thing that should be available at all the
planetariums/space museums.  There are simulators like this
on personal computers but the speed and sheer graphics brute
force of the Crimson really shine here.

A very remarkable experience!

Enjoy.

--
>Bob Witmer
>Eyring Corp., Flight Simulation Div.
>Salt Lake City, Utah
>[e-mail]

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

Date: Mon, 23 Nov 92 17:16:34 GMT
From: [e-mail]
Subject: Shuttle computers

> I wonder if they've ever considered a system by which a spare tape can be

> written by instructions from the ground, for checking and subsequent loading
> into the GPCs. That could be useful if (for instance) one of the flight
> control surfaces is damaged in an unanticipated way, and the basic flight
> protocol has to be modified. Writing to a tape would overcome some of the
> objections to direct loading of programs from the ground.
>


I see your point, but I suspect the time required to modify and certify the
flight software would be far too long. If the surfaces are damaged in some way,
could it actually be modeled quickly enough? Could a program written in low
level code be flight qualified and uploaded in time? I doubt it.

Probably better off going with the existing control program and using the
best flight control computer ever designed. Comes standard (1, each) with a
Right Stuff Pilot. Preinstalled between ears.

Now if you want to talk about noncritical flight regimes, that might be more
practical. Even so, the program development is (or at least was) one of the
major bottlenecks on shuttle flight rate.

Actually, calling these thing GPC is almost a misnomer. They run simple (by the
standards of complexity we are using to communicate with) sequential programs.
Only one program runs at a time. During critical flight phases the programs are
pre-loaded. On launch I think they also have an abort Major Mode loaded as well.
Each program also has minor modes, which are mostly display option I believe.

I'm not sure they even run an operating system. I don't think they even use
interrupts because that makes programs too unpredictable. All this is discussed
in great detail in the ACM paper whose citation I posted recently.

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

Date: 23 Nov 92 14:06:18 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space.shuttle,sci.space

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

>No Allan, what has been shown is that when you micromanage a program and or
>cut the budget below the request and or stretch the program to "save money"
>Nasa nor anyone else for that matter can complete a job in a cost effective
>manner.

Agreed. The problem is that exactly that is inevitable for any large program.
It is compounded by the fact that NASA feels that is the correct way to do
buisness.

>>I don't doubt that much cheaper expendables CAN be build (Zenith Star
>>launchers for example cut costs in half).

>The baby saturn can do the same thing.

You have yet to document any cost savings from baby saturn. If and when
you do I will be happy to embrase it.

>Funny thing is that the NLS 1 design ended up in the single engine
>configuration that we propose for the Baby  Saturn.

I suspect it was driven more by payload requirements and STME capabilities.

However, NLS1 (or Spacelift I as it is now called) will not save any
money. Even if it meets its development and operational cost goals it
won't save any money.

   Allen

--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
|  [e-mail]     |  nothing undone"                                       |
+----------------------152 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: 23 Nov 92 14:12:16 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

In article <[e-mail]> [e-mail] writes:
  >> That means all it needs for the second launch is to be re-fueled.

>Well, I'll pick a rather important nit: No pilot in their right mind
>gets behind the wheel/stick without doing a careful walkaround
>pre-flight.

To quote Sir Gawain: 'I stand a fool and you a wise man proved'.

>I expect that an operational DC1 vehicle will put the
>pilot back into the loop in a way they never were or could be on the
>Shuttle. With aviation style operations and complexity comes aviation
>style checklists and hands on pilot responsibility. And a hearty amen
>to that, brother.

That's an important point. When the Shuttle was first going up,
comentators called it 'the most complex vehicle ever built'. The
problem was that they said it like it was a good thing. Complexity
is NOT a good thing and its about time we realized it.

  Allen

--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
|  [e-mail]     |  nothing undone"                                       |
+----------------------152 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: Mon, 23 Nov 92 17:26:42 GMT
From: [e-mail]
Subject: Shuttle replacement

> On a related topic (your informative background on Delta Clipper) this
> sounds like an excellent idea, but I'm nervous about it. Having grown up
> in the Cape Canaveral area, and seen my share of boosters blow up or go
> tumbling into the Atlantic, the idea of a powered descent and vertical
> landing gives me the willies... I sure hope that thing has plenty of
> redundancy... rocket engines have a way of conking out at innopportune
> times.
>


Absolutely correct. And so do 747's. They make one *HELL* of a mess when they
come down on an apartment block. Too 747's don't go straight up and down so
they'd keep the incredible destruction of an accident inside the bounds of the
airport. (Tongue in cheek, but barely...)

Lets face it. The fuel load of a modern jumbo (and the superjumbo's they are
talking about in Europe) is not significantly different from a DC-1. Because
of the VTVL the DC-1 is probably less of a hazard to people than an airliner.
Accidents usually happen at take off and landing. Both of these will be much
more within the confines of the airport than airliners.

BTW... Did the pictures of the Isreali crash into an apartment block get shown
on the air over in the US (and the rest of the world) as much as here? Anyone
heard outcries to allow 747's to only take off and land over water?

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

Date: 23 Nov 92 15:09:00 GMT
From: "John F. Woods" <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

[e-mail] (Allen W. Sherzer) writes:
>In article <[e-mail]> [e-mail] (Brian Stuart Thorn) writes:
>>Whether or not it is efficient to do so is another question. I posted
>>another question about why Hubble Space Telescope is not brought back
>>home for repairs. There are many reasons in this case, mostly concerning
>>cost and loss of productivity (however limited it would be).
>Brinning Hubble back and flying it again would cost well over a billion
>$$. For less, we could build a new one and launch on a Titan.

And, of course, since Hubble wasn't designed to withstand the rigors of
being brought back (though that was the original intention), doing so could
result in *needing* to build a new one -- after having spent a billion dollars
:-).  [The ride down is not all that smooth, and Hubble is a big, delicate
piece of optics.]

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

Date: 23 Nov 92 18:58:09 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space.shuttle,sci.space

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

>It's not an accident that the more farsighted schemes for encouraging
>commercial launchers focus on guaranteeing a market, not on providing
>direct support.

The problem with a 'Kelly act for space' is that the Government can
no longer be trusted to maintain the program long enough to do any
good.

  Allen

--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
|  [e-mail]     |  nothing undone"                                       |
+----------------------152 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: 23 Nov 92 16:48:24 GMT
From: Christopher Neufeld <[e-mail]>
Subject: Solar sailing
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (John Roberts) writes:
>
>Most proposed solar sails are reflective, not black. That's because the
>principles of conservation of momentum show that reflecting the beam of
>light can greatly increase the thrust of the sail. The best results
>are with a 100% reflective sail perpendicular to the beam of light (theta = 0);
>that doubles the thrust.
>
   Well, yes, for certain definitions of 'best results'. Unless your
sail+payload has a very low mean mass per unit area, though, the net
force on the sail is still going to be sunward. Since the solar pressure
falls off as the square of distance just the way gravity does, the effect
of setting the sail at normal incidence to the sun is the same (from a
mathematical point of view) as instantaneously reducing the mass of the
sun while maintaining the position and velocity of the spacecraft fixed
over that instant. The result is a new orbit which circumscribes the old
one and is tangent to it at the point where the sail was unfurled. This
new orbit, of course, is closed, like any bounded orbit in an inverse
square field.  Now, for some trajectories this is desirable, but for most
it probably will not do.
   The usual trick is to set the sail at an angle to the spacecraft-sun
line. Since the radial component of the thrust does no net work over one
complete orbit (to first order, it helps a bit to second order if the
sail is not at normal incidence), the sail should be set at an angle to
maximize the tangential thrust. This angle is about 35 degrees for a
perfectly reflecting, planar sail. The sail can be angled to thrust along
the velocity vector or against it, and the orbital energy of the sail can
be raised or lowered this way, allowing the sail to move sunward just as
easily as it moves outward.
   A higher generation sail might be designed with a collector area at
normal incidence to the sun but which focusses the light onto a small
secondary reflector which can be steered rapidly to new directions. The
sail can be smaller for a given thrust. There will be some weight and
design penalties on making the reflector (which has to handle a very high
power flux) and making a sail which can focus accurately onto the second
reflector.

>John Roberts
>[e-mail]


--
 Christopher Neufeld....Just a graduate student  | Don't let your mind
 [e-mail]    Ad astra  | wander -- it's too little
 utzoo.utoronto.ca!generic!cneufeld              | to be let out alone.
 "Don't edit reality for the sake of simplicity" |

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

Date: Mon, 23 Nov 1992 14:07:57 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: SSTO Viability (was: Shuttle replacement)
Newsgroups: sci.space.shuttle,sci.space

In article <[e-mail]> [e-mail] (Rich Kolker) writes:

>Simulator testing for the DC-X/Y/1 pilots is underway.  As you know, DC-X
>will be flown remotely, DC-Y will be crew-capable.  Among the pilots trainingh
>is Pete Conrad.  If that name sounds familiar....it should!
    ^^^^^^^^^^^^^

It sure does! He was one of the actors on the made-for-tv movie Plymouth.

:-)

  Allen

--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
|  [e-mail]     |  nothing undone"                                       |
+----------------------152 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: 23 Nov 92 14:44:54 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: SSTO Viability (was: Shuttle replacement)
Newsgroups: sci.space.shuttle,sci.space

In article <[e-mail]> [e-mail] (Bill Goffe) writes:

>>We need to do other things as well. There was an article on this in
>>a recent issue of Design News

BTW, this is the September 7th issue page 58.

>>and the British newspaper The Guardian
>>is also working on an article.

>I understand that there will be an article in the British newspaper
>The Daily Telegraph on Nov. 20.

I stand corrected. The article will be in the Daily Tlegraph and I was
mistaken to think it would be in the Guardian.

It may not be on Nov. 20 but could be anytime from then to the middle
of December.

  Allen

--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
|  [e-mail]     |  nothing undone"                                       |
+----------------------152 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: Mon, 23 Nov 92 14:09:14 EST
From: "Prof. Eric T. Lane" <[e-mail]>

help

I'm writing an article on Physics resources on bitnet and internet.

Thanks, Eric Lane.

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

End of Space Digest Volume 15 : Issue 450
------------------------------