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Subject: SPACE Digest V13 #041

SPACE Digest                                      Volume 13 : Issue 41

Today's Topics:
         NASA Headline News for 01/09/91 (Forwarded)
             Re: Interstellar light sails
         Humankind's Second Off-world Colony
              Galileo Trajectory
          Re: LOX/LH2 in Shuttle Payload Bay
               Re: MIR Vacation
         turbine space power efficiency query

Administrivia:

    Submissions to the SPACE Digest/sci.space should be mailed to
  [e-mail].  Other mail, esp. [un]subscription requests,
  should be sent to [e-mail], or, if urgent, to
             [e-mail]

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

Date: 10 Jan 91 00:59:20 GMT
From: trident.arc.nasa.gov![e-mail]  (Peter E. Yee)
Subject: NASA Headline News for 01/09/91 (Forwarded)


             Headline News
Internal Communications Branch (P-2) NASA
Headquarters

  Wednesday, January 9, 1991    Audio Service: 202 / 755-1788

This is NASA Headline News for Wednesday, January 9, 1991

Kennedy Space Center ground team orbiter technicians continue
their processing of all three vehicles.  Discovery's forward
reaction control system and orbital maneuvering system pods
are currently being inspected.  Technicians working on Atlantis
have installed the remote manipulator system.  Interface tests
on the RMS system are now underway.  And on Columbia, the
hydraulic system is now undergoing inspection and testing.
Technicians are also performing post-flight work in Columbia's
crew cabin.

Payload technicians have begun fueling the Gamma Ray
Observatory.  A total of 4200 pounds of monomethyl hydrazine
will be loaded aboard the spacecraft.  This is nearly four times
more fuel than is required by most spacecraft, and will allow
GRO to take advantage of extended mission opportunities.

GRO is tentatively scheduled to be moved from its current
location, at the Payload Hazardous Servicing Facility, to the
Vertical Processing Facility on Feb. 6, where final spacecraft
tests will be carried out.

The Tethered Satellite, scheduled for flight on STS-46, arrived
at KSC on Nov. 13 and has been undergoing receiving
inspection and initial tests in one of the payload laboratories.
The first fit check of the satellite, with its payload deploy
mechanism, is scheduled to last about a week and will begin on
Jan. 17.

KSC recently named flow directors for two orbiters --
Discovery and Endeavour.  John J. "Tip" Talone was named
director for Endeavour, presently under construction by
Rockwell Space Division in Palmdale.  John C. "Chris" Fairey
was named flow director for Discovery, replacing Talone.  KSC's
flow directors are responsible for the management of all
activities associated with orbiter processing.

  * * * * * * * * * * * * * * * * * * * * * * * * * *

Galileo, moving at a solar orbital velocity of 84,000 mph, is now
15 million miles from Earth, and only 84.12 million miles from
the Sun.  On Friday, Jan. 11, Galileo will be 84.1 million miles
from the sun and at perihelion, the closest it will ever be to the
sun.  The spacecraft health and mission performance
continue to be excellent.  The first post-Earth cruise
sequence, uplinked on Dec. 17, is presently controlling all
onboard activities.  Cruise science operations have resumed and
the magnetometer, dust detector, and extreme ultraviolet
instruments are being read out every few days.

  * * * * * * * * * * * * * * * * * * * * * * * * * *

Astronaut William F. Fisher, M.D., will resign from NASA
at the end of this month.  He will return to full-time medical
practice as an emergency specialist at Humana Hospital-Clear
Lake,  near the Johnson Space Center.  Fisher was named an
astronaut in 1980 and flew on the STS 51-I mission in August
1985.  At that time, he, along with James van Hoften, performed
two spacewalks to fix the ailing Syncom IV-3 satellite.  The first
of the pair's two spacewalks was the longest ever, lasting 7
hours and 20 minutes.  Fisher was most recently co-chair, with
JSC robotics expert Charles Price, of the space station Freedom
external maintenance task force.

  * * * * * * * * * * * * * * * * * * * * * * * * * *

Adm. Truly is this year's honorary chairman of the
Tennessee Space Week, a state-wide aerospace education
program co-sponsored by the Tennessee Education Association
and NASA.  Marshall Space Flight Center staff have set
teacher workshops in Tennessee for the week of Feb. 9-15,
with student programs scheduled for the week of Feb. 18-22.
Admiral Truly will be in Nashville on Feb. 18 to kickoff the
student portion of the state program.



Here's the broadcast schedule for Public Affairs events on NASA
Select TV.  All times are Eastern.  **indicates a live program.

Wednesday, 1/9/91
     1:00 pm    **Combined Release and Radiation Effects Satellite
            Press Conference from NASA Headquarters.

     2:30 pm    **Magellan-at-Venus status report from  the Jet
            Propulsion Laboratory.

Thursday, 1/10/91
    11:30 am    NASA Update will be transmitted.



All events and times may change without notice.  This report is
filed daily, Monday through Friday, at 12:00 pm, EST.  It is a
service of Internal Communications Branch at NASA
Headquarters.  Contact:  CREDMOND on NASAmail or at
202/453-8425.


NASA Select TV:  Satcom F2R, Transponder 13, C-Band, 72
degrees West Longitude, Audio 6.8, Frequency 3960 MHz.

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

Date: Wed, 9 Jan 91 22:51:08 EST
From: John Roberts <[e-mail]>
Disclaimer: Opinions expressed are those of the sender
    and do not reflect NIST policy or agreement.
Subject: Re: Interstellar light sails


>From: cs.utexas.edu!swrinde!elroy.jpl.nasa.gov!euclid.jpl.nasa.gov![e-mail]  (Peter Scott)
>Organization: Jet Propulsion Laboratory, NASA/Caltech
>Subject: Re: Interstellar Light Sails

>In article <[e-mail]>, [e-mail] (Henry Spencer) writes:
>> >What is the spread of a laser over interstellar, or even interplanetary
>> >distances?  Last I heard from the deep-space laser communications people,
>> >there is large dispersion over even interplanetary distances ...

>> This says that at roughly
>> optical wavelengths (a few hundred nanometers), effectiveness at interstellar
>> distances (a light year is roughly 1e16 m) requires transmitters and
>> receivers hundreds of kilometers across.

>Exactly what Forward specifies, although I think he even talks in
>terms of apertures thousands of kilometers across.  He has designs,
>too; I recall a lens formed by a loose mesh enclosing an aerosol,
>don't remember how he handled diffusion but I assume he did.  The
>man thinks *big*.  Best example of someone with their head in the
>clouds but their feet on the ground that I know of.

>This is news.  This is your       |    Peter Scott, NASA/JPL/Caltech
>brain on news.  Any questions?    |    ([e-mail])

It might be interesting to see whether a phased array of transmitters could
do the job, as opposed to one gigantic mirror/lens. The math would certainly
be a challenge. :-)
       John Roberts
       [e-mail]

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

Date: 9 Jan 91 17:59:59 GMT
From: cadence![e-mail]  (Jon Monsarrat x6227)
Subject: Humankind's Second Off-world Colony

Hello! I am Jon Monsarrat, an MIT alum and avid reader of sci.space.

Some friends and I are writing a real-time real-space role-playing game,
set in the year 2180 on Ganymede colony. It's like writing a play, except
Acts 2 to 5 are made up by the actors as they go along. To set the whole
thing up we must write Act 1 including all the facts about the colony and
all the personalities, histories, and goals of the characters.

We want this to be as realistic as possible. I'd really appreciate any
comments, ideas, or non-technical book references on the following:

Where should Man's first colony after a moon colony be?
 OUR GUESS: Ganymede because of its water supply and proximity to Jupiter
  which is a good source of gases possibly used in fusion. Also I read
  about it in a very old Heinlein book! :)

What would the motivations for having a colony be?
 OUR GUESS: Less hostile environment than moon. Station for leaving solar
  system. Research growing food without special fertilizer and insects.
  Shelter for people leaving for political reasons. Biotech research too
  dangerous for Earth. Planetology. Parallax and other astronomy. Big
  surface areas for low-gravity research impossible in orbit.

What would be the basic physics of the colony?
 OUR GUESS: Ganymede has a huge crust of ice where any heat source would
  eventually sink. However there are (??) mineral deposit areas where you
  could build a city inside a crater and cover over the top of the crater.
  Evaporate some water for an atmosphere and add an inert gas to cut the
  oxygen. A "real colony" would be 2000 people and have to be tens of
  square miles with agriculture platforms stacked on top of one another.

What timeframe should we expect to have moon and Ganymede colonies?
 OUR GUESS: Men on mars 2040; Small moon base 2050; Big expansion to moon
  base(s) 2090; Good solar system propulsion invented 2100; Tiny Ganymede
  base 2120; Tiny mars base 2125; Expand Ganymede base to 300 people 2135;
  Expand Ganymede to 2000 people 2170. Good interstellar propulsion 2180.

How dependent would such a colony be on Earth?
 OUR GUESS: There are probably biological dependencies for growing crops,
  like some insect process, that we don't know about. To grow their food
  they might have to import soil from Earth. They can mine minerals,
  recycle air, build their own high-tech factories.

How might a Ganymede-Earth communication system work?
How often and when are there Earth-sun-Jupiter eclipses? How long are they?
 OUR GUESS: CommSattellite orbits Jupiter; endure silence during eclipses.

What are the long term effects of living in Ganymede's 1/7th gravity?
 OUR GUESS: This is mostly unresearched??

If low gravity was inhospitable to man, what would be the solution?
 OUR GUESS: Build a banked circular platform and maglev and rotate it to
  produce gravity?? Probably more worthwhile to live in Ganymede orbit
  (spinning for gravity), and land on Ganymede rarely.

Ganymede has a low pressure atmosphere, but what's it composition?
 OUR GUESS: 5 millibars water vapor??

I apologize if I have asked too many questions; there is really just one
question which is "any comments on our initial research?". We're curious
about {space,robot,computer,etc.} technology in 2180, but I know this is
too vague a question for this board. Please e-mail [e-mail] if
your response is not of general interest to sci.space. Thank you!!!

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

Date: 9 Jan 91 15:33:38 GMT
From: att!cbnewse!cbnewsd![e-mail]  (paul.h.nelson)
Subject: Galileo Trajectory

Could some knowledgable individual on the net explain why Galileo is flying
on the particular path this it is, (multiple fly-by's and all), rather than
a direct path to Jupiter.

I know vaguely that because of cost considerations the present plan was
chosen to make use of gravity assist.  However, it's still hard to visualize
how this is a faster and cheaper way to get to Jupiter--it's a much longer
path.  Don't understand the distance, velocity, path, and fuel tradeoffs.

Many thsnks,

Paul Nelson
Bell Laboratories
Naperville, IL

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

Date: 9 Jan 91 15:44:06 GMT
From: swrinde!zaphod.mps.ohio-state.edu!samsung!cs.utexas.edu!news-server.csri.toronto.edu!helios.physics.utoronto.ca!physics.utoronto.ca![e-mail]  (Christopher Neufeld)
Subject: Re: LOX/LH2 in Shuttle Payload Bay

In article <[e-mail]> [e-mail] ("Allen W. Sherzer") writes:
>
>Why not mount the Centaur upside down? That would put much less stress
>on the tanks since they would be riding on the 10K lb payload rather
>than the other way around. A harness could be built for the payload
>so it wouldn't rattle around if the fuel needed to be dumped. Of course,
>a way would need to be found to dump the fuel still.
>
   Yeah, and if it turns out that the shuttle could take the strain
better standing on its head we should build the stack for launch with
the engines pointing into the sky!   :-)
   Seriously, though, the pictures of objects leaving the cargo bay
always show the rocket nozzle of the Centaur or IUS pointing at the
floor of the payload bay, which would make the rocket horizontal in the
launch stack configuration. Is there a gimbal which swings the whole
thing to vertical, or is the payload actually mounted that way? If the
latter, it would be impractical to put the engine on top of the
payload.....

>|Allen W. Sherzer | America does best when it accepts a challenging mission. |
>|   [e-mail]   | We invent well under pressure. Conversely, we stagnate   |
>|                 | when caution prevails.   -- Buzz Aldrin                  |


--
 Christopher Neufeld....Just a graduate student  | "Shtarker! Zis is KAOS!
 [e-mail]    Ad astra! | Vee do not 'yippee yo
 cneufeld@{pnet91,pro-micol}.cts.com             | kye aye' here!"
 "Don't edit reality for the sake of simplicity" |      Siegfried of KAOS

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

Date: 9 Jan 91 20:18:45 GMT
From: usc!cs.utexas.edu!sun-barr!newstop!exodus!concertina.Eng.Sun.COM![e-mail]  (Steve Hix)
Subject: Re: MIR Vacation

In article <[e-mail]>, [e-mail] (Donald Heskett) writes:
>
> >Are there any viewports (aka windows)
> >on MIR?  When I get up there with my rolls and rolls of film, will
> >I be able to take any photos at all?
>
> >Don't tell me that my camera won't work up there;  I have the same camera
> >that NASA chose for their flights.  The Hasselblad was chosen because
>
> I don't know any aspect of camera operation that relies on gravity;
> they should all work as well in zero-gravity as they do in 1-g.
> Loading film might be somewhat more problematic than it is on the
> ground, however.

If you thought changing film with your camera was less than trivial...
try it while wearing a spacesuit!

> The Hasselblad uses removable backs that are pre-loaded with film.

One 35mm camera, the Rolleiflex 3003, has the same advantage as the
Hasselblad (and other similar 6x6 SLRs); removable backs.  Even one
that takes 100' rolls of film (800 or so exposures on a roll).
not be suitable for such an application.

Other than price, there may be other reasons that the Rollei might
> As far as the history of use of cameras in orbit, I'm pretty sure the
> shuttle astronauts usually use 35mm cameras these days, ditto the
> Soviets.  I seem to remember seeing a Nikon or two on the shuttle.

Olympus SLRs have been used, too.














--
------------
  The only drawback with morning is that it comes
    at such an inconvenient time of day.
------------

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

Date: 8 Jan 91 23:51:49 GMT
From: eagle!data.nas.nasa.gov!data![e-mail]  (Al Globus)
Subject: turbine space power efficiency query

I'm doing a mini-trade study to determine if space biospheres should
use direct sunlight (via mirrors) for interior lighting or generate
power and use electric lights.  One of the key parameters is the
efficiency with which sunlight can be turned into electricity.  Solar
cells give you maybe 10-20% efficiency - requiring arrays 5-10 times
larger than mirrors to generate the same amount of light in a habitat
interior.  Does anyone know what the efficiency of turbines
generating electricity from sun heated fluids?  Are there any studies
extrapolating earth based results to orbital figures?  Any help would
be greatly appreciated.  I know NASA Lewis is working on this but I
don't have any contacts.

Oh, by the way, if you have a reference for the figures that would
help a lot.  I may want to use the data in a paper.  Thanx.

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

End of SPACE Digest V13 #041
*******************