Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V10_2/V10_266.TXT

Internet Message Format | 1991-07-08 | 19KB

Return-path: <[e-mail]>
X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson
Received: from beak.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr11/tm2b/space/[e-mail] (->+dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl) (->ota+space.digests)
          ID </afs/andrew.cmu.edu/usr1/ota/Mailbox/oZOCejS00VcJ03Bk5:>;
          Tue, 21 Nov 89 01:26:56 -0500 (EST)
Message-ID: <[e-mail]>
Reply-To: [e-mail]
From: [e-mail]
To: [e-mail]
Date: Tue, 21 Nov 89 01:26:36 -0500 (EST)
Subject: SPACE Digest V10 #266

SPACE Digest                                     Volume 10 : Issue 266

Today's Topics:
            space news from Sept 25 AW&ST
                Re: Moon Ants
            Planetary data for space lift.
              Re: Mars Elevator
          Re: Planetary data for space lift.
            Re: Moon Colonies / Ant Tanks?
         NASA Headline News for 11/20/89 (Forwarded)
----------------------------------------------------------------------

Date: 19 Nov 89 21:48:41 GMT
From: mnetor!utzoo![e-mail]  (Henry Spencer)
Subject: space news from Sept 25 AW&ST

Space Industries Inc may revive its Industrial Space Facility as an "out
building" for the space station if budget cuts and engineering changes
make the station less suitable for microgravity work.  (In particular,
changes aimed at support of lunar operations might do this.)

Joe Allen, ex-astronaut and SII president, says that the biggest problem
for the Moon/Mars initiative is not engineering or funding but the
"ponderous laws of federal procurement".

SDI starts development of a $400M sensor-demonstration satellite for
launch in 1992.  This will be the first space test of sensors suitable
for use in an operational system.  It will go up on an uprated Titan 2
with eight small solid strapons, being developed by Martin Marietta.
The strapons will be variants of the Castor-4 used on the Delta.  They
will boost polar-orbit payload from 4200lbs to 7500lbs.  MM is covering
development costs; SDI is just buying the first launch.  MM thinks the
new Titan variant has commercial potential.

Virginia attorney general tries to get Avtex Fibers shut down for
polluting the Shenandoah river.  Avtex is the sole source of rayon yarn
used to make carbon-phenolic composites used in most US space and
missile systems.  Avtex has been in trouble on pollution rules before.

Ford Aerospace picked to modernize Mission Control at Houston and to
build a new control center for the space station.  Ford built the original
Mission Control in 1963.

Large article, with color photos, on Mir expansion plans.  Viktorenko
and Serebrov report that Mir is in good shape, but does need some work;
in particular, its batteries are getting old and need replacing.  Mir's
computer memory will be replaced by a new unit during September.  Details
of plans for add-on module installation etc. [now outdated because the
launch of the D module has slipped].  The D service module will be
followed by the T technological module, and later by the O optical
Earth-resources module and an "ecological platform".  Various small
changes will be done as modules go up, including transfer of solar panels
from module T to mountings on Kvant.

Soviets report that Titov and Manarov re-adapted to a one-gee environment
completely within two months of the end of their one-year Mir mission,
and no aftereffects have been seen.  Soviet doctors say that the extensive
program of exercise and other countermeasures is the main factor in this.
The cosmonauts were generally in better shape than others have been after
five-month missions; in particular, bone changes were "not more evident".
--
A bit of tolerance is worth a  |     Henry Spencer at U of Toronto Zoology
megabyte of flaming.           | uunet!attcan!utzoo!henry [e-mail]

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

Date: 20 Nov 89 22:48:02 GMT
From: amdahl!drivax![e-mail]  (MacLeod)
Subject: Re: Moon Ants

In article <[e-mail]>
[e-mail] (John Roberts) writes:

:I agree that there might be a problem with some of the kids (who never
:volunteered to live in space) being discontented, as well as adults who decide
:after a while that they want to return to Earth. However, I suspect that
:most kids would become accustomed to the environment in which they had been
:brought up, to the extent that they would probably be uneasy (at least at
:first) walking around unprotected on the open surface of the earth.

We already know that important physiological changes occur when a mature
human lives in free-fall for a period of time.  I would expect that children
born on the Moon will grow up with lunar-adapted skeletons and musculature,
and quite possibly would not be able to live on Earth in comfort, if at all.
Then there is the possibility (inevitability - *sigh*) of discrimination
between the two groups because they look so different to each other.

Michael SLoan MacLeod  (amdahl!drivax!macleod)

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

Date: 11/20/89 15:59:18
From: [e-mail]
Comment: CROSSNET mail via SMTP@INTERBIT
Return-Receipt-To: [e-mail]
Subject: Planetary data for space lift.

There has been a number of messages about the slow rotation of the
Moon prohibiting any selenostationary cable. Indeed, it is the
planet's rotation that makes the sky hook hold in the air under its
own weight, but the only requirement is that the planet does rotate.
This being the case for any known body, the rotation only gives a
small bonus both on the cable's resistance and on the energy needed
to transfer loads on stationary orbits. The other advantage is that
the stationary orbit is lower when the rotation is high, so that the
cable is shorter. But once again, the limiting factor is the cable's
cross-section, not its length.

Remember: Delta( Log(S) ) = p/s.r0.g0.(1 + x/2 -3/2.x^(1/3) )
where 'x'=w^2.r0.g0 is the ratio between centrifuge force and
gravitational acceleration on the equator. Usually the
corresponding reduction factor is negligible or only a few percent,
so that the order of magnitude of the cable's dimention and weight
is controlled by the r0.g0 factor, for a given material (for which
p=density and s=maximal traction per square meter are constants).

Here is the data for the inner planets (copied from a russian book,
so this may be desinformation...):

  !Planet !    w     :  r0   : g0   :   r1  :  r0.g0  :reduction!
  ! name  !E-6rad.s-1: E6 m  :m.s-2 :  E6 m :E6.m2.s-2: percent !
  !-------------------------------------------------------------!
  !Venus  !    0.30  : 6.052 : 8.86 :1536.8 :  53.62  :  0.0    !
  !Earth  !   72.72  : 6.371 : 9.81 :  42.2 :  62.45  : 22.6    !
  !Mars   !   71.24  : 3.397 : 3.71 :  20.4 :  12.60  : 25.     !
  !Mercury!    1.24  : 2.44  : 3.68 : 242.4 :   8.98  :  0.     !
  !Moon   !    2.66  : 1.738 : 1.63 :  88.6 :   2.83  :  0.0    !

Moon's figures just give an order of magnitude, since Earth's
attraction adds a small bonus: the two Lagrange points are at
58 E6.m for the inner one (288_557 furlongs) and at 65 E6.m for the
outer one (35_519_125 fathoms - I love these old english units).

The table shows our bad luck: of all the reachable planets, Earth is
the one where the energy expense to reach synchroneous orbit is the
largest, when rotation is not taken into account. When this
correction is taken into account, the figure falls down to
48.4 E6.m2.s-2, some ten percent under Venus - which is definitely
the unreachable planet. Mars' fast rotation together with its small
gravity makes it almost as easy to reach as Mercury, and with a much
shorter cable.

For outer planets, the size and ground(?) acceleration clearly
prohibits any cable for the time being. (Exept of course for Pluto -
but who wants to go there anyway?)  The data for their larger
satellites might be nevertheless useful, but we can wait a while
before we reach them and use them industrially.

The cable's construction consists basically in launching a
synchroneous satellite plant, a big spider wich will spin the cable
both up and down so as to remain in equilibrium. The gravitation
field tends to align both cables toward the planet's center, whereas
the cable's progression tends to tilt it due to gyroscopic effect.
For a proper progression, both effects cancel out (and the cable has
a constant tilt).  Once the cable reaches the ground, one simply has
to anchor it, then add some weight at the other end so as to put it
under tension (otherwise the cable would be unable to lift anything:
adding a payload at the bottom would merely pull the satellite
down...).

The plant need not be a synchroneous one, of course, thought it
simplifies the matter.  As Michel van Roozendaal pointed out (13
nov. 89), the cable itself can be used to control the station's
final altitude: if a load is thrown downward before the cable is
anchored, the station will be pulled upward, and mutatis mutandis an
upward load thrown into space will lower the station. As soon as the
cable is anchored, up and down traffic change the planet's momentum
and not the satellite's, so that the corresponding energy is free
and the effect negligible.


This can be helpful for Mars: as Paul F. Dietz said in this forum
(17 nov. 89), Phobos can be pulled in higher orbit using a tether
that throws part of its mass on Mars. Of course, this has to be done
before we send anybody down there. (Pebbles in the sky? Who said
that?)  Phobos is not that large (a couple of kilometer across), so
that digging out part of it is not much of a problem once you get
there. *BUT* this only give a synchroneous orbit: how can it be
turned into a Mars-stationary one (that is: bring Phobos' orbit into
Mars' equator)?

This is also useful for the Moon: it would be useless to build a
plant in sel.-station. orbit, since the target Lagrange points are
unstable: the plant would tend to drift away, and correcting the
trajectory of a thousand-kilometer long satellite might be tricky.
It would probably be easier to assemble the cable on a lower stable
orbit, then give the station a final pull up while bringing down
some weight and the last part of the cable. Et voil'a.

                             Bertrand MICHELET
                             uDoc140 at FrOrs31 (BitNet)

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

Date: Mon, 20 Nov 89 18:56:50 EST
From: John Roberts <[e-mail]>
Disclaimer: Opinions expressed are those of the sender
    and do not reflect NIST policy or agreement.
Subject: Re: Mars Elevator


>From: sei![e-mail]  (Robert Firth)
>Subject: Re: Mars space elevator

>In article <[e-mail]> [e-mail] (John Roberts) writes:
>>This problem was discussed in Fountains
>>of Paradise by Arthur C. Clarke. The proposed solution was to set up a
>>carefully-controlled vibration in the elevator, which would cause it to
>>move out of the way as Phobos passed by.

>Um... wouldn't it be a lot simpler to move Phobos?

Several people have pointed out that it would be an undertaking way beyond
current technology to get Phobos beyond synchronous orbit or crash it into
Mars. While this is true, there is an alternative which is "not quite as
impossible". The Martian day is about 24.62 hours. Phobos orbits Mars in
about 7.65 hours. If this period could be increased to around 8 hours,
so that it was exactly equal to 1/3 of the period of a synchronous
orbit, it seems to me that it could be set up to always pass over the
equator at certain fixed points. You could then pick a spot that it never
passes over, and build the elevator there. Of course, you might have to
periodically adjust Phobos' orbit to maintain this relationship, which would
be a nuisance.
                                 John Roberts
                                 [e-mail]

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

Date: 21 Nov 89 02:19:45 GMT
From: jarvis.csri.toronto.edu!me!helios.physics.utoronto.ca!physics.utoronto.ca![e-mail]  (Christopher Neufeld)
Subject: Re: Planetary data for space lift.

In article <[e-mail]> [e-mail] writes:
>
>This is also useful for the Moon: it would be useless to build a
>plant in sel.-station. orbit, since the target Lagrange points are
>unstable: the plant would tend to drift away, and correcting the
>trajectory of a thousand-kilometer long satellite might be tricky.
>
>                             Bertrand MICHELET
>                             uDoc140 at FrOrs31 (BitNet)

   Please, somebody correct me if I'm wrong. The L1 and L2 points are 2/3
stable points, so that a mass which drifts in the plane perpendicular to
the line connecting the two masses tends to drift back to the L1/L2 point.
The unstable direction is radial. If it falls slightly toward the earth, it
will keep falling that way. The converse is also true. Since the tether
would be anchored at the moon, and held under tension by the ballast
weight, it seems to me that this situation should still be dynamically
stable. Of course, I'm ignoring quadrupole mass effects for the earth and
the moon, and the sun's gravitational force. Still, it should be fine
without active maneuvering.

--
 Christopher Neufeld....Just a graduate student  | "Space probe may be
 [e-mail]                    | Doomsday machine!"
 [e-mail]              |   -Toronto Star article
 "Don't edit reality for the sake of simplicity" | on Galileo 19/11/89

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

Date: 18 Nov 89 01:18:26 GMT
From: zephyr.ens.tek.com!tektronix!psueea!parsely!bucket![e-mail]  (Leonard Erickson)
Subject: Re: Moon Colonies / Ant Tanks?

[e-mail] (daniel mocsny) writes:

>What does this have to do with space? Industries and economies that
>are not spectacularly profitable in an environment with more
>advantages than anyplace else in the solar system will not work
>elsewhere. The only way to overcome the expense of an inherently
>hostile environment is to increase the productive ability of each
>individual. This translates ultimately into giving the individuals
>more Information Power. Of course we will do this anyway whether
>we go to space or not. But if you want to get something viable
>going upstairs, that is the place to start.

You are assuming that space is a hostile environment *in general*.
For many industrial activities, space or the moon have *advantages*.
The disadvantages have to do with the need to give workeres more
protection from the environment.

Semi-silly example. A steel mill in space can obtain high temperatures
more easily and *maintian* them even more easily. Vacuum is an advantage
here. Gravity may or may not be desired. Once you get to the point
where you are working on the billets then the situation is more
nuetral, or possibly even slightly negative (lubrication is harder
in space, cooling is a *lot* harder).
--
Leonard Erickson        ...!tektronix!reed!percival!bucket!leonard
CIS: [70465,203]
"I'm all in favor of keeping dangerous weapons out of the hands of fools.
Let's start with typewriters." -- Solomon Short

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

Date: 20 Nov 89 19:23:07 GMT
From: trident.arc.nasa.gov![e-mail]  (Peter E. Yee)
Subject: NASA Headline News for 11/20/89 (Forwarded)

-----------------------------------------------------------------
Monday, November 20, 1989                     Audio: 202/755-1788
-----------------------------------------------------------------

This is NASA Headline News for Monday, November 20....


Project officials at Goddard Space Flight Center report that the
Cosmic Background Explorer satellite is operating well following
its launch into near polar orbit last Saturday.   The COBE
spacecraft was placed into orbit by a Delta rocket.  The delta
rose off the pad ten minutes into the half-hour launch window
after high winds aloft finally abated enough to allow the
lift-off.  COBE was placed into a 559-mile circular orbit.


As COBE scientists prepare for their one-year search for remnants
of the big bang some 15 billion years ago....astronomers at
Palomar Observatory report that they have located a quasar 14
billion light years from earth making it the most distant and
oldest object ever discovered.


Workers continue their pre-launch pad operations at Kennedy Space
Center aiming for a Wednesday lift-off of the space shuttle.
Discovery's five-member crew arrived at KSC Sunday afternoon.
Pad workers were running behind schedule over the weekend
completing work on the the right hand Solid Rocket Booster
Following replacement of an Electronic Controller Unit.  Launch
Director Robert Sieck told United Press International it would be
"a very tight fit in terms of being finished in time" for
Wednesday evening's scheduled launch.

Discovery's payload bay doors have been secured and today pad
personnel are closing out the aft compartment of the orbiter.
The classified Department of Defense mission will be launched
sometime after 6:30 P.M., Eastern time, Wednesday.


Last Friday, NASA Administrator Richard Truly provided members of
the National Space Council with the results of a 90-day study
aimed at establishing a manned base on the moon and a manned
mission to Mars.  The report came about as the result of
President Bush's space initiative earlier this year.  The paper
spelled out issues and discussed special technology required for
the two proposed programs.


The White House has released an unclassified version of a revised
national space policy.  The document, approved by the President
earlier this month, contains strong support for human exploration
of the solar system and for commercial space ventures.

                  *          *         *


-----------------------------------------------------------------
Here's the broadcast schedule for public affairs activities on
NASA Select TV.  All times are Eastern.


Wednesday, November 22......

    5:30 P.M.     Coverage begins of the STS-32 launch only of
                  the space shuttle orbiter Discovery. The
                  mission is classified.


This note:        NASA Update will not be transmitted this
                  Thursday because of the Thanksgiving holiday.

All events and times are subject to change without notice.
-----------------------------------------------------------------
These reports are filed daily, Monday through Friday, at 12 noon,
Eastern time.
-----------------------------------------------------------------
A service of the Internal Communications Branch (LPC), NASA
Headquarters, Washington, D.C.

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

End of SPACE Digest V10 #266
*******************