Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V12_5/V12_583.TXT

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Subject: SPACE Digest V12 #583

SPACE Digest                                     Volume 12 : Issue 583

Today's Topics:
              Re: Photon Engine
             Re: The Space Plane
            X-30 = The Space Plane != X-29
              Colored satellites
           Re: The great light bulb debate
                Zero-G

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

Date: Wed, 21 Nov 90 17:02:44 EST
From: John Roberts <[e-mail]>
Disclaimer: Opinions expressed are those of the sender
    and do not reflect NIST policy or agreement.
Subject: Re: Photon Engine


>From: wuarchive!julius.cs.uiuc.edu!ux1.cso.uiuc.edu!news.cs.indiana.edu!maytag!watdragon!watyew![e-mail]  (Brian or James)
>Subject: Re: Photon Engine

>    I may be misremembering, but I don't think the lasers are intended
>for use in a 'pure' photon engine. Photon engines have to have very impressive
>power supplies to generate large values of thrust (Power = C x Force, or
>something? My mind is going...). My impression was that they use the land
>based laser to evaporate reaction mass, with the benefits of not having to
>carry the powerplant to orbit, and being able to achieve higher exhaust
>velocities.
>    Granted, once you're in orbit, low thrust isn't a problem (if
>you are patient), but surface to orbit launches work better if the
>thrust is higher than the local gravity :)

>                            James Nicoll

Yes, F = power / c, where F is in Newtons, and c = ~3E8, so the systems we
were describing would consume huge amounts of energy and yet have a thrust
of only a few Newtons at best, and they would therefore be unsuitable for
earth launch.

The laser launcher system proposed by LLNL, etc. would work on an entirely
different principle. In this case the laser is only used to transmit power
from the power plant to the launch vehicle, so the weight of the power plant
will not have to be lifted. As you describe, the laser heats a reaction
mass, creating thrust. The reaction mass can be a block of ice, another
solid such as polyethylene, or just the air under the craft (heated by contact
with a metal plate, most useful for the first part of the trip, to save the
solid reaction mass for later on).

Theoretically, power consumption can be modest, acceleration gentle, and even
some degree of steering possible. Perhaps Jordin Kare could describe the
proposal in more detail (it's been a while).
       John Roberts
       [e-mail]

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

Date: 20 Nov 90 16:57:02 GMT
From: swrinde!cs.utexas.edu!news-server.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: The Space Plane

In article <[e-mail]> [e-mail] (John Prentice) writes:
>is NASP still intended to achieve orbit without rocket assist or have
>they conceded defeat on that one?

They've conceded defeat, last I heard, and NASP will use rockets for the
final portion of a flight to orbit.
--
"I don't *want* to be normal!"         | Henry Spencer at U of Toronto Zoology
"Not to worry."                        |  [e-mail]   utzoo!henry

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

Date: 20 Nov 90 09:38:12 GMT
From: m2c!wpi.WPI.EDU![e-mail]  (MEGAZONE 23)
Subject: X-30 = The Space Plane != X-29

In article <[e-mail]> [e-mail] writes:
>I'm fairly certain NASP is a commercial venture. What I'm not sure of
>is, is NASP the same as the X-29? Maybe the X-29 is the military vehicle
>you're talking about.

The NASP is a government venture. DARPA, NASA, USAF I believe. It is the
X-30. The X-29 is the Foward Swept Wing research aircraft, of which there
are two. The X-29 has been flying for some time now. It is a Grumman aircraft.

###############################################################################
#  "Calling Garland operator 7G," EVE           Email [e-mail]    #
# MEGAZONE, aka DAYTONA, aka BRIAN BIKOWICZ     Bitnet Use a gateway. Sorry.  #
###############################################################################

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

Date: Tue, 20 Nov 90 17:28:56 EST
From: John Roberts <[e-mail]>
Disclaimer: Opinions expressed are those of the sender
    and do not reflect NIST policy or agreement.
Subject: Colored satellites


>From: unmvax!ariel.unm.edu!ghostwheel.unm.edu![e-mail]  (John Prentice)
>Subject: Re: STS 38 Observation Reports -- red?

>Why do you suppose Lacrosse looks red?  I assume they would not have
>painted it (and if they did, would you paint it a light absorbing
>color like red?).   Are there solar panels that might reflect that
>color?  Interesting.  I must admit, in many years of satellite tracking,
>I don't recall ever having seen a color associated with a satellite,
>so this is intriguing (I also have faith in Beresford's observations).

>John Prentice
>Dept of Physics
>University of New Mexico

I don't know whether there's any relation, but the TDRS satellite, launched
from the Shuttle as a boring-looking cylinder, unfolds into a real work of
art. They've got one on display up near the ceiling at the National Air and
Space Museum, close to the V-2, the spare Skylab, and the HST engineering
prototype. I presume the gold parts of TDRS are for thermal/meteorite
protection, as on the Lunar Module.

TDRS is basically a set of antennae. According to many reports, Lacrosse
has a very large antenna. Larger/brighter objects are more likely to show
color, because of the optical properties of the eye. (For instance, stars
are much more colorful seen through a telescope.)
      John Roberts
      [e-mail]

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

Date: Wed, 21 Nov 90 14:42:57 -0900
From: "ACAD3A::FSRRC" <@BITNET.CC.CMU.EDU:[e-mail]>
Sender: "ACAD3A::FSRRC" <@BITNET.CC.CMU.EDU:[e-mail]>

ISECCo Update:  Summer of '90: A supremely successful summer.
November 21, 1990
     We got a jump on our summer projects, staring work in early May, getting
2 greenhouses, 2 gardens and a significant amount of work done at the  hanger
site, not to mention getting the hole excavated for the biosphere  structure.
June, July and August saw us pushed for time due to outside projects, but  we
still  managed to get raise chickens, expand the aquaculture  (fish)  system,
and keep up with the garden.
     Our primary volunteer workers were Ray Collins, Terry Fike, and R. Scott
Guse.  The ISECCo Vice President, Joe Beckenbach, visited from California for
a  couple  of weeks in June (as a part of winning the ISECCo  Most  Donations
Award  Joe  got a 5 day sailing trip on Prince William Sound)  and  assisted.
Other  people  who  were  instrumental in  our  summer  success  are  Chandra
Schaffer, Elisa Corning and Kelly Wilkinson.  A few others, like Robert  Hale
and  Pat Wilkinson, helped out as needed.  All in all we totaled  nearly  800
man-hours of labor over the summer.

The Greenhouses
     While  it may not appear that growing gardens is a function of  a  space
group  our  gardens  serve two purposes: they allow  us  to  experiment  with
various  means  of  growing  things which will  ultimately  be  used  in  the
biosphere,  and  second  they provide food for our  volunteer  workers.   Our
greenhouses are especially important for developing techniques for  biosphere
crops.
     The  first greenhouse we build was primarily for hydroponics.  It was  a
8'x12'  frame structure covered with fiberglas sheathing.  Inside we built  4
trays,  3 of which held gravel and the 4th of which was soil.  All  of  these
trays  were watered with hydroponics solution; the gravel with  new  solution
and the soil with either old solution or water.
     We  planted tomatoes, bell peppers, and brussels sprouts in  the  gravel
and rutabaga, beets, radishes, cantaloupe and squash in the soil.  We  hadn't
ever  tried growing crops like this so we weren't sure what we were going  to
get.  While we did get a fair crop it could have been improved;  The tomatoes
were touched a bit by a late frost, the brussels sprouts failed to produce at
all (too much competition from the tomatoes they were planted next to?),  the
radishes  went to seed and the cantaloupe didn't have a long  enough  growing
season (this was expected).  In spite of these troubles we harvested  gallons
of  tomatoes,  a bucket full of peppers, all the rutabaga  we  desired,  beet
greens, and several squash.
     The  second  greenhouse  was an 18' x 40' structure,  made  from  poles,
string  and  visqueen (clear tarps) put up over a good patch of  ground.   We
planted  corn, squash, cantaloupe, beans potatoes and beets in it.  In  spite
of overheating problems (it got into the 100's regularly during June) we  got
squash, corn, beans and beets.
     The  cantaloupe (in both greenhouse) didn't have a long  enough  growing
season.   This  was  expected, but it did serve to show us the  size  of  the
plants  and  to  give us an idea about soil  requirements.   Another  notable
failure  was  the potatoes in the visqueen greenhouse: we had hoped  to  have
potatoes  in early-mid July, but it was the end of the growing season  before
they could be harvested.  This was most likely due to heat stress.

The gardens
     Our gardens were both located in newly turned soil, and neither location
(one being at my house and the other being at the hanger site) has good soil.
In  spite  of  this  our crops did quite well.  We  are  in  the  process  of
upgrading  the soil with horse manure from local farms, chicken  manure  from
our chickens and earthworm casts from our earthworm trays.  Over the next few
years we hope to improve the soil to the point where our crops will flourish.
     The  garden at my house was 9 meters (30') x 12 m (40'), and is  located
on  a  south facing slope in a (primarily) silt soil.  We had a  garden  here
during the summer of '89 and plowed this area with a rented rototiller before
we  planted.  Over the summer we expanded the area for the garden, and it  is
now  12 m. (40') x 20 m. (60').  We used the cat (tractor) to turn  over  the
new  ground, and pulled most of the sticks out of it.  We expect it to be  an
easy job to plow it next spring, though we haven't improved it's soil yet  so
it may not produce very well next summer...indeed, we may leave it fallow for
another year.
     The garden at the hanger site is of a similar size.  It was formed  from
top  soil  dug from where the hanger is being built and dumped in  a  cleared
part of the lot.  The area is slightly south facing (5 degrees?), and is well
protected  from wind by the surrounding trees (which, unfortunately, tend  to
shade it during the early morning.  The soil was somewhat better than that at
my  house,  but  is  still  nothing  to  brag  about.   This  coming   summer
construction will probably prohibit planting this garden.

Biosphere Construction
     The  First  CELLS,  the name of our biosphere (a  NASA  acronym  meaning
"Closed   Ecological   Life  Support  System"),  is  being  built   on   land
'lease/donated'  by  Marilyn Rowley.  Included in the lease is the use  of  a
mobile home, which was used to house our volunteer workers this summer.  As a
part of the deal we cleaned up the trailer, and got it to the point where  it
could  be lived in by early May.  Scott and Terry spent the entire summer  in
the trailer, and Robin and Chandra lived there occasionally.  The  excavation
for the biosphere is right behind the mobile home, and most of the dirt  from
from the excavation was used to make a large parking pad in front.
     Construction  this summer was 'limited' to digging the  biosphere  hole.
This  immense  excavation  took  about a month to  dig  with  the  Catepillar
Tractor,  which  was  on loan from TANSTAAFL Inc.  The hole is  12  m.  (40')
square  and  averages 8 m. (26') deep.  We will dig another  1-1.5  m  (3-5')
before pouring the foundation, for we have just gotten through the silt (into
gravel)  in  one corner of the hole and it is advisable to  have  the  entire
foundation in gravel.
     I have been attempting to get pictures showing the size and depth of the
hole,  with  limited success.  So far the best I've gotten have  been  aerial
photos  taken from a Super Cub (a 2 seater airplane).  If you would  care  to
see  some  of my attempts send a SASE to us at the address below and  I'd  be
happy to send you a few black & white prints.

The Aquaculture System
     We  upgraded  our  fish system to a capacity near what will  be  in  the
biosphere.   We have a 15 gallon aquarium, a 20 gallon aquarium, a 70  gallon
bath  tub, a 4'x6'x2' tank (360 gallons), and a 2'x4'x2' tank (120  gallons).
These latter two aren't operational yet; we have been trouble with the  liner
outgassing (we think!)
     Our  fish population started with 20 Tilapia a year ago and  since  then
we've  breed them twice; the first time we got around 80 and the second  time
around 60.  We have lost 30-40 to various causes, so we now have a population
of about 125.  The largest of these is 8" long and weighs 1/4 pound, close to
the  optimum size for harvest.  It appears that it will take a year  to  grow
them  to  this size, so for a harvest of 2 every other day we  would  need  a
population of 365 fish, or about 3 times our current population.

The Chickens
     While it has not yet been determined that we shall have chickens in  the
First  CELSS  we  did  want  to experiment  with  them.   Elisa  Corning  was
instrumental  in getting our poultry system established.  She raised  several
varieties  of  birds in a cage behind her house.  While it is  too  early  to
determine  whether  they  will fit into the ecosystem or not,  we  have  been
gaining valuable experience in their habits and requirements.

ON  OTHER  MATTERS:
     In  June the Directors of ISECCo held a meeting, and at that meeting  we
voted  to  begin preliminary investigations on what is required  to  build  a
live model of a aerospace plane.  The purpose of this model would be to  have
a  device  which  would  be capable of  hypersonic  velocities  for  critical
component testing.  Unfortunately this will be limited (at this point) to  an
intellectual  exercise  since all of our funds are being put into  the  First
CELSS.
     This fall/winter we are in the process of upgrading the systems that  we
have developed thus far in an attempt to begin some preliminary cycling.   We
plan to tie the dehumidifiers to the fish and chickens; the fish and chickens
to the hydroponics system (which is a part of the plant system) and the plant
system will provide water (vapor) for the dehumidifiers.  While none of these
'ties'  will  be closed, it will give us a working idea of  how  things  will
work.   We  will also gain experience in rates of  nutrient  flow,  determine
potential limits and discover the some of the problems (and cures?).


Those  of you who wish to know more can write me at FSRRC@ALASKA, or via  the
postal system at the address below.  Please include a postal mailing  address
for  all  initial BITNET correspondence--we occasionally have  letters  whose
computer return address fails for one reason or another.

                                   --Ray R. Collins:: President, ISECCo

      :::The International Space Exploration and Colonization Company:::
               :::P.O. Box 60885::Fairbanks::Alaska::99706:::
                        Researching  and  Developing
                    space oriented  technology  for  the
                           betterment of mankind.
     *     *    *    *    *    *    *    *    *    *     *     *    {end}

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

Date: Wed, 21 Nov 90 18:28:51 EST
From: John Roberts <[e-mail]>
Disclaimer: Opinions expressed are those of the sender
    and do not reflect NIST policy or agreement.
Subject: Re: The great light bulb debate


>From: zephyr.ens.tek.com!wrgate!mtdoom![e-mail]  (Dan Tilque)
>Subject: Re: The great light bulb debate

>[e-mail] (Henry Spencer) writes:
>>
>>Krypton is better than argon for the same reason that argon is better than
>>vacuum:  the denser gas slows the evaporation of the tungsten filament.

>Obviously we need to take this to it's logical extension.  It's time to
>start recycling all that radon that everyone has in their houses.

>And I want no namby-pamby whining about radon being radioactive.  In a
>lightbulb, that's not a bug, it's a feature.

>Dan Tilque    --    [e-mail]

The mantles for gas lanterns are made with radioactive thorium oxide
(presumably because of its mechanical properties at high temperatures).
A reference book I have also states that it is included in trace quantities
in the tungsten filaments of light bulbs (!).
         John Roberts
         [e-mail]

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

Date: Wed, 21 Nov 90 14:01:39 EST
From: John Roberts <[e-mail]>
Disclaimer: Opinions expressed are those of the sender
    and do not reflect NIST policy or agreement.
Subject: Zero-G


>From: sun-barr!newstop!exodus!norge.Eng.Sun.COM![e-mail]  (John McKernan)
>Subject: Re: LNLL Inflatable Stations

>[e-mail] ("Allen W. Sherzer") writes:
>>An inflatable station could be made smaller for 0G however if they are
>>to maintain artificial gravity, it is about as small as they can get. It's
>>not clear which has more life cycle cost. Crew can be left on a spinning
>>station for a year with no problems.

>Soviet crews have stayed in orbit for over a year. They have demonstrated
>that with advanced exercise machinery and lots of exercise it is possbile
>to return to the Earth after a year in a 0g environment and completely
>recover.

"Recover" is the key word. Apparently nobody stays up there that long and
remains what could objectively be called "healthy". As an ideal, a stay
in space should be no more destructive to the human body than a comparable
period on the earth.

NASA (or a spokesman thereof whom I heard recently) has stated that it has
no interest in chemical means to combat calcium loss - it prefers vigorous
exercise, clean living, pure thoughts, ritual chants, and so on. Since the
loss of bone calcium is essentially a chemical (or electrochemical) activity,
I don't think they should be so quick to summarily dismiss the possibility
of therapy involving chemical treatment. For that matter, a drug to block
decalcification would be useful to many women on earth.
     John Roberts
     [e-mail]

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

End of SPACE Digest V12 #583
*******************