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Subject: SPACE Digest V11 #35

SPACE Digest                                      Volume 11 : Issue 35

Today's Topics:
    Soviet Soyuz TM-9 mission begins to Mir space station
               RE: SSX and Propellants
          Re: Spacecraft drives and fuel efficiency
          Re: Spacecraft drives and fuel efficiency
          Re: Galileo Update - 02/06/90 (Forwarded)
                Re: Nasa Freq.
            Re: metric vs. imperial units
          Re: Spacecraft drives and fuel efficiency
  Easy come, easy go (was Re: Spacecraft drives and fuel efficiency)
          Re: Spacecraft drives and fuel efficiency
               Re: Recreation in Space
----------------------------------------------------------------------

Date: Sun, 11 Feb 90 13:40:55 EST
From: Glenn Chapman <[e-mail]>
To: [e-mail], [e-mail],
        [e-mail], [e-mail],
        [e-mail]
Subject: Soviet Soyuz TM-9 mission begins to Mir space station

     The USSR successfully launched its Soyuz TM-9 mission on Feb. 11th
(though the launch time was only stated as this morning). The crew for this
6 month mission are Anatoly Solovyov (Soyuz TM-5/Mir Jun. '88 for 9
days) and Alexander Balandin, a new cosmonaut, as expected.  The Soyuz TM-9
will rendezvous with Mir on Feb. 13th.  There they will replace the current
cosmonauts Alexander Viktorenko and Alexander Serebrov who have been in
orbit for 159 days, since Sept. 5, 1989.  The original schedule for the
current crew called for them to come down on Feb. 24th but the Feb. 9th
announcement said that it may be Feb. 19th. One of the more important items
that Viktorenko and Serebrov will be bringing down in the Soyuz TM-8
capsule will be the crystallization protein experiments paid for by Payload
Systems of Cambridge, MA.  One of the main tasks of the new crew will begin
with the docking of the Kvant 3 or Technology module which will occur in
March/April this year. This 17.2 Tonne expansion section will dock with the
front axial docking port of Mir, then be swung to the side port using a robot
arm to dock opposite to the Kvant 2 module.  Kvant 3 will be 13.7 meters (45
ft.) long (the same length as Kvant 2) but has a huge solar array some 36
meter (118 ft.) in span that is planed to generate some 20 Kilowatts of
power.  By comparison Mir itself has only a 29.7 meter (97 ft.) spanning
array, and the total of its power, plus that of arrays added on Kvant 2 and
erected during space walks, is only 20 Kilowatts itself.  The main task of
Kvant 3 is material processing, especially the growth of super pure
crystals.  The Soviets argue that this module will begin the point where
materials processing on Mir will pay for the missions. (Radio Moscow Feb.
8-11)
     One interesting point has been pointed out about the next mission,
Soyuz TM-10, scheduled for July '90.  As noted in my previous posting one
of the stated crew members is Vitally Serastyanov, an old time cosmonaut,
selected in 1967, flew Soyuz 9 in June 1970 for 17 days, Soyuz 18/Salyut 4
in May 1975 for 63 days and was a manager in the Soviet Lunar Landing
training program.  However, Jonathan McDowell of the Harvard Smithsonian
Observatory, pointed out to me that Serastyanov retired in 1975 and became
a well known science journalist on Russian television/radio.  This suggests
that he is the Soviet reporter to fly to Mir to beat the Japanese
journalist which been moved up from 1991 to the fall of this year.  At 55
years old this probably makes him the first astronaut/cosmonaut to retire,
take on other tasks, then to return again to space to make use of his old
training in a new field.
    Definitely the Soviet manned program is becoming more commercial.  Let
us see if they can, in their own minds, make a profit in space.

                                                  Glenn Chapman
                                                  MIT Lincoln Lab

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

Date: 11 Feb 90 00:03:33 GMT
From: zaphod.mps.ohio-state.edu!van-bc!rsoft!mindlink![e-mail]  (Bruce Dunn)
Subject: RE: SSX and Propellants


Having watched this discussion unfold for a while, i would like to do something
absolutely horrible to those of you who have been hopping up and down
excitedly about high-density propellants: I'm going to break out some Numbers.

For instance:  The space shuttle ET
The space shuttle's external tank weighs 78,100 lbs [nominal] when empty.
when filled with the full fuel load of 1,359,000 lbs LOX and 226,000 lbs
of LH2, the total tank mass is 1,663,000 approx and the fraction of this that
is the tank itself is one part in 21.  Liquid hydrogen is by far the lowest
density fuel around.  That the tankage for it is negligible compared to the
fuel mass sort of knocks holes in the idea of getting more mileage out of
higher density fuels.

Counterarguements of the type that any decrease in the final mass [rocket eqn]
is a significant advantage can as far as i can tell be effectively countered by
the decrease in Isp for the denser fuels compared to LH2.

If anyone out there has a more in-depth analysis showing me wrong, please post
it and/or email me.  But all my design studies are staying LH2 burners for the
time being :-)


*********************************************************************** *****
George William Herbert |  UCB Naval Architecture [On schedule? at UCB? Yes!]

     I agree with this line of reasoning only as long as the objective is to
lower the total gross mass of a vehicle.  However, it is usually the dry mass
of a rocket which costs a lot, not the propellant.  To a first approximation,
the cost of a vehicle is proportional to its dry weight.  For first stage use
in a multi-stage vehicle, a pencil and paper calculation will quickly show you
that hydrocarbon fuels will give a lower dry mass than LH2 would.  Granted, the
total stage mass will be higher because of the lower specific impulse, but this
increased mass is cheap fuel and oxidizer, not expensive hardware.  However,
for upper stage use or for stages where a lot of delta V is required from a
single stage, specific impulse becomes more important than density.
     Researchers who have been modeling two stage or single stage to orbit
vehicles have generally found that burning subcooled propane during the first
part of the flight reduces total hardware masses by 5 to 10% over the mass of
an all hydrogen vehicle.  This is not a huge difference, but it is real.  In
practice, as Henry Spencer has pointed out, the availability of suitable
engines may be much more important than theoretical considerations in
determining how a vehicle is to be built.  Certainly, if hydrogen is to be used
for the upper stage of an ascent and the engine can be adapted for lower stage
work by modifying its expansion ratio, it may be desirable to go with a single
engine design rather than have the complication of two engine types.
     The most promising engines for future vehicles are dual fuel engines which
can burn both a hydrocarbon and hydrogen.  The relative proportion of thrust
and propellant used in each mode can then be fine tuned to a specific vehicle
and ascent profile.
     For anyone wishing to persue this topic further, I can E-mail them some
literature references.
     - Bruce

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

Date: 11 Feb 90 22:18:33 GMT
From: ogicse!unicorn![e-mail]  (Matthew Skinner)
Subject: Re: Spacecraft drives and fuel efficiency

In article <[e-mail]> [e-mail] (Steve Nuchia) writes:

>Robert Forward's solution to this excersize (_Flight_of_the_Dragonfly_)
>was to release the main reflector at turnover and use the reflected
>(and refocused) beam to deccelerate the ship using a smaller secondary
>reflector.  The former main reflector is of course accelerated further
>on the outbound axis.  This was a one-way mission, [...]

Dr. Forward describes a two way trip in his book _Future_Magic_ which
uses the outermost ring to decelerate the ship, then a middle ring to
reflect the laser to accelerate the center sail back home.


--
Matthew Skinner                          skinner@ [ nessie | unicorn ].wwu.edu

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

Date: 11 Feb 90 19:22:02 GMT
From: nuchat![e-mail]  (Steve Nuchia)
Subject: Re: Spacecraft drives and fuel efficiency

In article <[e-mail]> [e-mail] (H Keith Henson) writes:
>energy to laser light.  Lasers will levitate against 1g, and as someone
>(Henry?) recently said, a year at one gee is the speed of light.
>(How to stop is left as an exercise)  Keith Henson

Robert Forward's solution to this excersize (_Flight_of_the_Dragonfly_)
was to release the main reflector at turnover and use the reflected
(and refocused) beam to deccelerate the ship using a smaller secondary
reflector.  The former main reflector is of course accelerated further
on the outbound axis.  This was a one-way mission, and involved a lot
of coasting since the deceleration phase has limited delta-v.  As in
most light sail problems the bulk of the reflector (or thrust/mass
ratio if you prefer) is one of the biggest remaining exercizes.
--
Steve Nuchia          South Coast Computing Services      [phone]
"If the conjecture `You would rather I had not disturbed you
 by sending you this.' is correct, you may add it to the list of
 uncomfortable truths."   - Edsgar Dijkstra

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

Date: 11 Feb 90 23:41:13 GMT
From: cs.utexas.edu!sun-barr!newstop!texsun!convex![e-mail]  (Richard A. Schumacher)
Subject: Re: Galileo Update - 02/06/90 (Forwarded)


This is also the first time a probe will approach the earth-moon
system from a great distance, which should permit the best determination
to date of the Earth's mass (right, Henry, Ron?)

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

Date: 10 Feb 90 21:20:29 GMT
From: mtndew![e-mail]  (Steve Friedl)
Subject: Re: Nasa Freq.

> For all you space fanatics, here is a listing of all of the radio frequencies
> that NASA uses. It's 463 lines long.

I assume that there are all kinds of data streams going to and
from the Shuttle (and to other things like Voyager or Galileo).
Does NASA ever get worried about electronic sabotage over these
frequencies?  Is everything encrypted?

     Steve

--
Stephen J. Friedl, KA8CMY / Software Consultant / Tustin, CA / 3B2-kind-of-guy
[phone] voice   /   [e-mail]   /   {uunet,attmail}!mtndew!friedl

"Winning the Balridge Quality Award is as easy as falling off a horse." - me

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

Date: 12 Feb 90 01:06:32 GMT
From: eru!luth!sunic!sics.se![e-mail]  (Per Danielsson)
Subject: Re: metric vs. imperial units

In article <[e-mail]>, gregw@otc (Greg Wilkins) writes:
>You guys just keep making excuses!!!!   Yes an entire country can convert
>from imperial to metric -> Eg Australia and we have the safest airline in
>the world.  If any airline or spaceflight relies on the pilots ability to
>do mental arithmetic in his native units, then it aint safe!!

I'm quite sure that aviation in Australia uses feet for altitudes and
nautical miles for distances, just as the rest of civilian aviation in
the world (with a few exceptions: the USSR being the one really
important one, but russian pilots have to use feet and nm when they
fly outside the USSR. (The other group I know of using meters and km
in the air is the Swedish Air Force)).
It's of course not impossible to convert everyone to meters (witness
the co-use of air space and Air Traffic Control of civilian and
military traffic in Sweden), but it will be *very* expensive in large
parts of the world.

Converting to SI (i.e. "metrics") in other areas is another matter.
I'm all for it. ("The U.S. is going metric inch by inch.")

>The whole point is that metric has many big points in its favour:
>
> - The rest of the world is using it

Agreed.

> - To some extent, when designing physical systems, recurring decimal
>   places can be avoided, hence round off errors can be reduced.

This I don't understand. Why is any measurement system better than
another here?

> - To do any sort of calculation by computer, metric is by far better than
>   imperial, thus reducing the possibility of program error.

This, too, I fail to understand. Computers don't care about
measurement systems.

>...
>[Stuff deleted]
>...
>Anyway, to sum up, stop making excuses, start making changes, put a bit
>of effort in , and maybe, just maybe you will be able to talk technical
>with the rest of the world in twenty years or so!

I agree completely. The U.S. is becoming more and more dependent on
cooperation with the rest of the world, since it is not as dominating
in the world economy nowadays as 20-30 years ago. This alone should
make americans a little worried about the lack of progress in
converting to SI.
--
Per Danielsson        UUCP: [e-mail] (or ...!enea!sics!pd)
Swedish Institute of Computer Science
PO Box 1263, S-164 28 KISTA, SWEDEN

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

Date: 11 Feb 90 21:32:29 GMT
From: rochester![e-mail]  (Paul Dietz)
Subject: Re: Spacecraft drives and fuel efficiency

In article <[e-mail]> [e-mail] (Tim Maroney) writes:

>You have to realize just how enormous the energy costs are in
>interstellar travel.

They are certainly enormous compared to current energy usage.
But then, the energy cost of sending a spacecraft to the moon
is large compared to the energy used by stone-age man.

The energy resources of the solar system are more than adequate for
interstellar travel, given sufficiently massive engineering.  The sun
produces about 4e26 watts of power.  At 100% efficiency, this power is
enough to launch, every *second*, a 15 million ton starship at half
the speed of light.  Implementation details are left to the reader :-).

    Paul F. Dietz
    [e-mail]

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

Date: 12 Feb 90 03:00:29 GMT
From: zaphod.mps.ohio-state.edu!uakari.primate.wisc.edu!xanth!xanth.cs.odu.edu![e-mail]  (Frank C. Paterra)
Subject: Easy come, easy go (was Re: Spacecraft drives and fuel efficiency)

In article <[e-mail]> [e-mail] (Steve Nuchia) writes:
   In article <[e-mail]> [e-mail] (H
Keith Henson) writes:
>>energy to laser light.  Lasers will levitate against 1g, and as someone
>>(Henry?) recently said, a year at one gee is the speed of light.
>>(How to stop is left as an exercise)  Keith Henson
>Robert Forward's solution to this excersize (_Flight_of_the_Dragonfly_)
>was to release the main reflector at turnover and use the reflected
>(and refocused) beam to deccelerate the ship using a smaller secondary
>reflector.  The former main reflector is of course accelerated further
>on the outbound axis.  This was a one-way mission, and involved a lot
>of coasting since the deceleration phase has limited delta-v.  As in
>most light sail problems the bulk of the reflector (or thrust/mass
>ratio if you prefer) is one of the biggest remaining exercizes.

Assuming you guys have solved all the problems of accelerating
the ship, how about when you reach the half way point, pointing
the solar sail at the destination star and using it to decelerate
the ship?

>--
>Steve Nuchia          South Coast Computing Services      [phone]
>"If the conjecture `You would rather I had not disturbed you
>by sending you this.' is correct, you may add it to the list of
>uncomfortable truths."   - Edsgar Dijkstra

Simple idea from a simple mind.

Frank Paterra
[e-mail]
--
Frank Paterra
[e-mail]

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

Date: 11 Feb 90 07:58:48 GMT
From: pasteur!sting![e-mail]  (Scott Silvey)
Subject: Re: Spacecraft drives and fuel efficiency


> Unfortunately, the speculative "gate" approaches such as the Kerr
> metric warp are even worse.  Has anyone done any estimates on the
> energy needed to keep a Kerr warp contained and spinning?

What is a "Kerr metric warp", who is Kerr, and what sort of physics
  does this involve?  Is this merely some science fiction conjecture
  or is it based on reputable theory?

How do you estimate how much energy it takes to induce one?

Scott

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

Date: 11 Feb 90 23:35:55 GMT
From: zaphod.mps.ohio-state.edu!rpi!crdgw1!sixhub![e-mail]  (Wm E. Davidsen Jr)
Subject: Re: Recreation in Space

In article <[e-mail]> [e-mail] (WATMOST Groups 9) writes:

| Finally, do what would YOU like to do if you were a crewman on the Space
| Station?  Could zero gravity itself be entertaining enough, or would you
| desire some form of activity?  Can you suggest an object, such as a
| gyroscope, that would be interesting to use in zero-g, and should be provided?

  Let me give you a hint... if I were going to be on a multiyear
mission, I would want female astronauts.
--
    bill davidsen - sysop *IX BBS and Public Access UNIX
[e-mail]        ...!uunet!crdgw1!sixhub!davidsen

"Getting old is bad, but it beats the hell out of the alternative" -anon

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

End of SPACE Digest V11 #35
*******************