Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V10_1/V10_195.TXT

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Subject: SPACE Digest V10 #195

SPACE Digest                                     Volume 10 : Issue 195

Today's Topics:
              Re: Manned Jupiter Mission
       Balloon Launch attempt of a High Power Rocket (40 miles)
         NASA Headline News for 10/31/89 (Forwarded)
            a glimpse behind Venus's veil
             Rock sizes in space
              Voyager trajectory diagram
         Re: Manned Jupiter Mission (was Re:
----------------------------------------------------------------------

Date: 31 Oct 89 01:56:50 GMT
From: [e-mail]  (Terry Hancock)
Subject: Re: Manned Jupiter Mission

In article <[e-mail]> [e-mail] (Mark Gellis) writes:
>Regarding long term manned missions in space...
>
>I've heard talk of using magnetic fields to deflect cosmic rays, particles,
>etc.  This would supposedly lower the mass of the hull necessary to protect
>the crew of a spacecraft from radiation.  Is this true?  Workable?  What is
>involved in setting up such a "radiation shield"?
>
    Yes ... in principle.  This is what protects us on Earth and in
LEO.  However, there are serious problems.  There is a significant danger
of actual *increasing* the radiation levels this way.  I've also heard
mention (I think) of an electrostatic shield (repel charged particles by
direct Coloumb force law rather than trapping them in magnetic fields).

    The problem, basically, is with controlling large enough magnetic
fields to act as shields, and preventing the trapped particles from
being dumped onto the spacecraft.  Consider, for example, the problem
of turning the field off safely -- if you shut it off suddenly, a good
number of your trapped shielding particles will spray through your ship
on their way to inifinity.

    The last description I read on this was published in the mid-70's,
so with the improvements in superconducting materials, it may be easier
to do.  They said it was beyond their technology, however, to build the
necessary magnets -- or rather that they would be far too massive to be
practical.

>In addition, because I am interested in space colonization, I was wondering
>what kind of shielding would be necessary (assuming magnetic fields, etc.
>won't work as well as people would like) to protect people from the long
>term background radiation of space.  I heard something around two meters of
>asteroid/lunar rock should be enough to stop pretty much everything; I was
>wondering if this was true.
>

    I heard (same source as above -- an L5 station design study, but I
don't remember the name), that 10 tonnes per square meter of exposed
surface would be required.  Suppose you use lunar rock (a sort of slag,
let's say) -- 10 Mg/m^2 is about 3.3 m thick.  If you built out of
a Ni-Fe asteroid, it'd be about 1.4 m thick.  This is not exactly true,
since density doesn't directly map to radiation cross-sections, but it's
good enough for speculation.  In any case, this thing will be HEAVY.  It
will almost certainly outweigh your spacecraft.

    There are other options though.  Mostly what you're worried about
are sporadic outbursts of solar activity (not the continuous level of
radiation).  So, you can design a short-term use shield -- perhaps covering
only one hemisphere (roughly speaking) of your ship, or just thicker on
one side.  You just point that end towards the Sun during flares.

    Or, how about finding uses for your sheild?  Water will stop a
fair amount of radiation, so will your fuel.  So, why not just put all
that stuff in an orientation so that you can point it at the Sun during
high activity.  This is, as I understand it, the solution planned for the
Mars mission (if & when...).

    Yes, I know that charged particles don't follow straight paths,
but since it's the fast ones you're worried about, it's not a bad
approximation.  And, yes, you do need to have some sheilding all-around,
I'm merely suggesting that it be concentrated on one side.

>One final question.  If magnetic fields for radiation shielding will work,
>how much power would it require.  Also (okay, I know this is two questions),
>
    Good question.  Depends on how efficient you can get your magnets
to be.  Also, since the radiation flux is highly variable, so will be your
power losses.  Perhaps, if indeed you CAN get away with only shielding
during flares, you can turn it completely off except when needed.

>can it operate if the object is moving relatively fast, like a spacecraft
>moving from one location in a solar system to another?
>
    Shouldn't affect it -- other than that it will be heavy.

    By the way, developing electromagnetic sheilding technology is
probably vaguely related to developing a Bussard ram scoop.  Any
thoughts about that?

>Thanks in advance.
>
>     Mark Gellis
>     f3w%mentor.cc.purdue.edu

*************************************
Terry Hancock
[e-mail]
*************************************

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

Date: 31 Oct 89 00:35:33 GMT
From: megatest![e-mail]  (Ivan Batinic)
Subject: Balloon Launch attempt of a High Power Rocket (40 miles)


    in article <[e-mail]>, R. Michael Jungclas Writes:

>...For now, he's going to be launching a
>2.6" diam. rocket from a balloon at an alititude of about 120,000'
                               ^^^^^^^
    ...

>...A TV camera on the balloon will be able to cover the launch
      ^^ ^^^^^^
>(hopefully).  The rocket will carry a flight computer and transmitter
                                       ^^^^^^ ^^^^^^^^     ^^^^^^^^^^^
    ...

    I am very interested in such a venture.  A few engineering
problems come to mind (besides the balloon/rocket separation!). I'm
curious about environment control: It seems to me that even some MIL-
Spec components cannot function in the temperatures you can expect at
those altitudes.  Particularly since the balloon launch will prolong
the flight computer's idle stay in the upper atmosphere.  Was such an
environment control device also placed on-board, or deemed not neces-
sary?

>... I will keep you informed of any further developments.

    If the net is inappropriate for more detailed discussions on
this subject (and if I am not intruding) I would appreciate E-Mail
correspondance.  Thankyou for submitting this interesting article!

    Ivan

    Email:    {sun,decwrl,fortune,pyramid}!megatest!ivan

    DisClaimer: My opinions are my own and do not necessarily
            reflect those of this organization.

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

Date: 31 Oct 89 21:06:23 GMT
From: trident.arc.nasa.gov![e-mail]  (Peter E. Yee)
Subject: NASA Headline News for 10/31/89 (Forwarded)

-----------------------------------------------------------------
Tuesday, October 31, 1989                     Audio: 202/755-1788
-----------------------------------------------------------------

This is NASA Headline News for Tuesday, October 31....


The STS-33 crew completed the Countdown Demonstration Test
for Discovery at Kennedy Space Center yesterday.  Commander Fred
Gregory, Pilot John Blaha and Mission Specialists Manley Carter,
Story Musgrave and Kathryn Thornton showed a sense of humor by
wearing costume hats and carrying artificial jack-o-lanterns on
their way to the launch pad.

Target date for the launch of the DoD mission is November 20.  A
firm date is expected to be set at the conclusion of the Flight
Readiness Review on November 6 and 7.


(Correction)  The NASA budget, a part of the VA, HUD and
Independent Agencies Appropriations Bill was n-o-t sent to the
White House Friday.  The Senate sent the bill back to the House
for a vote on an amendment not associated with the NASA
appropriation.  Action on that amendment is expected today.  The
bill will then go to the White House with signing by the
President expected sometime next week.


With the Hubble Space Telescope now powered up at Kennedy Space
Center, engineers have begun a series of checks of onboard
instruments and systems.  A satellite link between the Lockheed
plant in Sunnyvale, Calif., and KSC is being used for data
transmission during the tests.  Other tests will be conducted
between the Hubble Payload Operations Control Center at Goddard
Space Flight Center and KSC also using the new satellite link.
Launch of the telescope is scheduled for March 1990.


The flap over Avtex Fibers' Front Royal, Virginia, rayon yarn
plant continues.  The state water control board is being asked by
the state attorney general to revoke Avtex's permit to discharge
toxic waste into the Shenandoah River.  The plant produces
special rayon yarn used in the manufacture of DoD and NASA solid
rocket motors.  If the board revokes the permit the plant would
shut down.  If closed Avtex would most likely appeal the decision
in court.


And....a new Intelsat V communications satellite is scheduled to
achieve geostationary orbit today and deploy antennas later this
week.  The spacecraft was launched aboard an Ariane  booster last
Friday.

            *             *            *           *


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

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


Wednesday, November 1....

      2:00 P.M.      STS-34 post flight news conference from
                     Johnson Space Center.

      2:30 P.M.      Following news conference...the quarterly
      (approx.)      "Aeronautics and Space Report".


Thursday, November 2.....

     11:30 A.M.      NASA Update will be transmitted.


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.

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

Date: 1 Nov 89 00:38:12 GMT
From: bridge2!3comvax![e-mail]  (Michael McNeil)
Subject: a glimpse behind Venus's veil

Avid tourists of the Solar System won't want to miss the geological tour
of a portion of Venus's surface that's included in the 20 October 1989
article in *Science* "Styles of Volcanism on Venus: New Arecibo High
Resolution Radar Data."  After some preparation -- moseying, say, down
to your local U.S. Geological Survey office (for example, the office at
345 Middlefield Road in Menlo Park, California), there purchasing the
"Altimetric and Shaded Relief Map of Venus" (a beautiful map, color
coded for the elevations of Venusian terrain), and after orienting
oneself to the scale and locations of Venusian features described in
the article -- thereupon is revealed unparalleled high-resolution radar
"photographs" of Venusian mountain and plain, complete with analysis.

I think it's a tour de force (comparable in its way to Voyager in
revealing an un-Earthly realm to us), and the team that accomplished
this feat all the way from Earth is certainly due multiple huzzanahs!
(And mucho thanks to the authors of the article, a beautiful job....)

Anyway, the radar "photographs" show glaring, obvious, spouting-all-
over-the-landscape examples of volcanism on Venus.  It's completely
garish in the case of Theia Mons (a major peak in the Venusian region
known as Beta Regio, where several major rift zones intersect).  It's
as if someone had squirted spaghetti all over the country, dribbling
down every little fault -- it's quite a sight, go check it out....

(And how about this -- in only one week, not only a tour of Venus, but
another brilliantly lucid [IMHO] article "The Chemistry of Solid-State
Electronics," by E. Yablonovitch -- and an honorable mention: "Burgess
Shale Faunas and the Cambrian Explosion."  Sock it to me, oh "National
Enquirer" of *Science*!  Week after week; I can take it!  "Ahhh...!!!")

--
Michael McNeil            [e-mail] (3comvax.UUCP)
3Com Corporation        hplabs!oliveb!3comvax!michaelm
Mountain View, California    work telephone: [phone] x 5-208

References

[1]  "Altimetric and Shaded Relief Map of Venus," Atlas of Venus,
1:50,000,000 Topographic Series, V50M 6/60 RKT, 1981, published by
the U.S. Geological Survey.

[2]  Donald B. Campbell, James W. Head, Alice A. Hine, John K. Harmon,
David A. Senske, Paul C. Fisher, "Styles of Volcanism on Venus: New
Arecibo High Resolution Radar Data," *Science*, 20 October 1989
(vol. 246), pp. 373-376.

[3]  E. Yablonovitch, "The Chemistry of Solid-State Electronics,"
*ibid.*, pp. 347-351.

[4]  S. Conway Morris, "Burgess Shale Faunas and the Cambrian
Explosion," *ibid.*, pp. 339-346.

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

Date: 1 Nov 89 02:03:53 GMT
From: cs.utexas.edu!mailrus!jarvis.csri.toronto.edu!utgpu!radio.astro!helios.physics![e-mail]  (Christopher Neufeld)
Subject: Rock sizes in space


   I read something recently in a science fiction book, and would like to
know where the science ends and the fiction begins. The book made mention
of a rule which stated that for each object in the solar system of a given
diameter, you could expect to find ten objects with a diameter one third as
great. Is there any real evidence of a rule to this effect?


Note: new path. I can finally get rid of that annoying disclaimer.
--
 Christopher Neufeld....Just a graduate student  | New degree, new
 [e-mail]                      | supervisor, new
 [e-mail]              | project, and a
 "Don't edit reality for the sake of simplicity" | new path. NOTE.

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

Date: 1 Nov 89 03:02:24 GMT
From: mailrus!jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Voyager trajectory diagram

A little while ago, in one of my AW&ST summaries, I was quite taken with
a perspective diagram of the trajectories of the Voyagers with respect to
the planets.  I've just discovered the original; it's in JBIS (the
Journal of the British Interplanetary Society), Oct 1985, page 440.
In black&white rather than pretty color, but larger and more legible
(and incidentally, much easier to reproduce).
--
A bit of tolerance is worth a  |     Henry Spencer at U of Toronto Zoology
megabyte of flaming.           | uunet!attcan!utzoo!henry [e-mail]

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

Date: 31 Oct 89 17:50:40 GMT
From: gem.mps.ohio-state.edu!wuarchive!brutus.cs.uiuc.edu!samsung!shadooby!mailrus!jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Manned Jupiter Mission (was Re:

In article <[e-mail]> [e-mail] writes:
>... one of the greatest challenges of
>even a manned trip to Mars is that of radiation shielding from cosmic
>radiation...

Unless the general opinion has changed since I last heard it, cosmic rays
are a big issue only if you plan to spend a significant fraction of your
life outside the Van Allen belts.  A couple of years is a significant
exposure but not a particularly worrisome one.  No Mars-expedition plan
that I'm aware of uses cosmic-ray shielding en route, although ideas
for significant stays on the surface tend to involve buried living
quarters.

>... If astro/cosmonauts spent 18 months flying to Mars in the
>traditional 5-10 cm thick hulled tin can that has been the tradition for space
>crafts flown under the Earth's Van Allen belts...

Uh, 5-10 *centimeters*?!?  More like a few millimeters, unless you count
a certain amount of equipment in as shielding.

>If humans did make it to Jupiter, I would think that, unless they have very
>good shielding, would head either for the cover of >5 m of Jovian moon dirt or
>for the underside of the Jovian radiation belts!

It depends on how long they're staying there.  For a lengthy stay, local
dirt would be a good thing to have.  The problem with getting inside the
Jovian Van Allen belts is that you have to pass through them -- and
that is a radiation problem that makes cosmic rays look insignificant.
A human passenger aboard one of the Voyagers, which zipped through at
very high speed, would have taken a very-probably-lethal dose.
--
A bit of tolerance is worth a  |     Henry Spencer at U of Toronto Zoology
megabyte of flaming.           | uunet!attcan!utzoo!henry [e-mail]

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

End of SPACE Digest V10 #195
*******************