Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V10_1/V10_190.TXT

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Subject: SPACE Digest V10 #190

SPACE Digest                                     Volume 10 : Issue 190

Today's Topics:
              Galileo Questions
             Re: Galileo Schedule
    Re: Balloon Launch attempt of a High Power Rocket (40 Miles).
            environmentalist .NE. luddite
Truly updates aeronautics and space programs for Press Club (Forwarded)
                 Re: Galileo
             Looking at Atlantis
         Re: Asteroids as weapons of mass destruction
     Re: Trying to build a fluxgate magnetometer -- help!
     Re: Trying to build a fluxgate magnetometer -- help!
----------------------------------------------------------------------

Date:     Thu, 26 Oct 89 15:38:31 CDT
From: Will Martin <[e-mail]>
Subject:  Galileo Questions

Thanks to Peter Yee for the posting of the STS-34 Press Kit. There's a
lot of good info in there and it answered most of my questions about
Galileo right at the start!

I do have a few minor queries:

1) I seem to recall some traffic on the SPACE Digest some months or even
years back about litium batteries in space-rated hardware. As I recall
the discussion, it seemed to be that lithium batteries were not allowed
in payloads going up in the Space Shuttle, due to the risks of their
exploding or outgassing or doing something else nasty. The Galileo probe,
however, is powered by lithium batteries. I assume nothing else would
give the long 5-year dormancy followed by a brief 75-minute spasm of glory
as the probe executes its brief mission. :-)

Am I recalling the earlier discussion correctly? If so, was the restriction
on lithium batteries only on *commercial* versions? I am assuming these probe
batteries are not "stock" off-the-shelf items but instead specially
constructed custom components designed for this mission, and thus may be made
far safer than ordinary versions. Is this the case?  If so, can anyone
describe briefly how these differ from commercial versions? Are we likely to
see a spinoff from this for very-high-reliability commercial batteries, or
very-safe versions for use in explosive atmospheres or other critical
applications?

2) This is actually much more general than just Galileo-related: the
"T-minus" countdown chart included in the press kit listed a number of
"built-in holds", such as the one at T-27 hours and so forth. Why is the
countdown constructed this way? Why build in a "hold" of 8 hours instead
of just lengthening the countdown period by 8 hours and scheduling the
actions that take place during this hold at the same relative time?
It would appear on the surface that a "hold" should always be an
exceptional condition -- something caused by a problem -- as opposed to
a regular scheduled event expected to occur at some scheduled time.
There must be a good reason for these built-in holds, but I can't figure
it out. I'd appreciate enlightenment on the subject.

3) This is purely speculative -- I've been trying to figure out some
in-flight use for the many pounds of ablative heat shield that burns off
the probe during Jupiter-atmosphere entry. The problem is that it can't
be anything consumable, like maneuvering-thruster fuel, which would be
used during the flight, because that mass has to be there to be burned
off as heat shielding when the probe enters. Also, it has to be dense
and massive and approachng homogeneous, so it will function adequately
as ablative material. So far, the only thing I've been able to think of
is densely-packed electronics embedded in some potting compound. Or
perhaps some really futuristic crystalline mass of computing circuits
based on nanotechnology? (How about an AI that takes measurements
during the flight but then dies a fiery death during the probe entry?
Shades of HAL -- what a motivation to sabotage the mission! :-)

Maybe some sort of entirely-solid-state scanning mechanism to take
detailed star-chart type images during those long lonely years of travel
between slingshot points? Any other ideas?

(I'm sure better minds than I had spent many long hours trying to come
up with some sort of productive use for that otherwise-inert and
extremely-expensive-to-ship weight; anyone from NASA care to post any
notes on what might have been proposed, if anything?

Regards, Will Martin

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

Date: 28 Oct 89 23:32:20 GMT
From: mailrus!jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Galileo Schedule

In article <[e-mail]> [e-mail] (Alex White) writes:
>From personal experience with normal tape units of many varying types
>for computers, I know I would never want to leave a tape unit unattended
>for more than about say 10 minutes, or they screw up badly.
>What would happen with the dramatic temperature variations I'd hate to think.

Well, the temperature variations are less than you would think.  One major
problem of spacecraft design is maintaining temperatures within the bounds
of the equipment specs.  I.e., they just don't let it vary that much.
Voyager is wrapped in thermal blankets everywhere except for antennas and
camera apertures, and much of the equipment has built-in heaters.

Tape recorders *have* historically been a reliability headache for space
missions, even though this is spare-no-expense equipment.

>Voyager also apparently had a tape recorder -- this lasted for many
>years, many many replays -- and I never heard that they had any problems
>at all.

Well, actually there was one associated problem, sort of:  starting and
stopping the tape induced torques on Voyager that interfered with keeping
it stable enough for maximum-precision camera pointing.  Really.  Midway
through the mission, the on-board software was changed so that recorder
stop and start operations include small thruster firings to compensate!
--
A bit of tolerance is worth a  |     Henry Spencer at U of Toronto Zoology
megabyte of flaming.           | uunet!attcan!utzoo!henry [e-mail]

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

Date: 26 Oct 89 17:26:17 GMT
From: calvin![e-mail]  (John Sahr)
Subject: Re: Balloon Launch attempt of a High Power Rocket (40 Miles).

In article <[e-mail]> [e-mail] (Brad Templeton) writes:
>But what good is a baloon rocket launch?  When it comes to getting into
>orbit, 90% of the problem is gaining horizontal velocity, not going through
>the atmosphere or gaining altitude.
>--
>Brad Templeton, ClariNet Communications Corp. -- Waterloo, Ontario 519/884-7473

1)  Not everyone who wants to launch rockets wants to go into orbit.

2)  Atmospheric stresses are a significant constraint on sounding rockets,
    enough so that some of them _must_ be launched straight up, or they
    spend too much high speed time in the denser, lower atmosphere.

caveat: I'm not a rocket dude, but a radar dude.

--
John Sahr,                   | Electrical Engineering - Space Plasma Physics
[e-mail] | Cornell University,         Ithaca, NY  14853

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

Date: 26 Oct 89 15:27:21 GMT
From: deimos.cis.ksu.edu!uafcveg!uafhcx![e-mail]  (6079 Smith J)
Subject: environmentalist .NE. luddite


Hey folks, I know the Christics have screwed up.  But Please don't use
'environmentalist' either as an insult or as a synonym for 'technophobe.'
There are perfectly sane people, even engineers, who believe that
unlimited growth/consumption is wrong and recycling is necessary.  The
pollution problem is real.  In sci.space, a discussion of SRB exhaust
pollution is perfectly legit.  Don't sneer at people with real concerns.


|  James W. Smith, University of Arkansas  | uafhcx![e-mail] |
|    I'm so depressed.  If I didn't have so much to do, I'd be a nihilist.   |

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

Date: 26 Oct 89 17:51:07 GMT
From: trident.arc.nasa.gov![e-mail]  (Peter E. Yee)
Subject: Truly updates aeronautics and space programs for Press Club (Forwarded)

[Don't ask me what they mean by the title of this release.  We don't normally
work for the Press Club. :-)  -PEY]

Jeff Vincent
Headquarters, Washington, D.C.
1:00 p.m. EDT
October 26, 1989

RELEASE:  89-165

TRULY UPDATES AERONAUTICS AND SPACE PROGRAMS FOR PRESS CLUB

     Four months after becoming NASA Administrator, Vice Admiral Richard
H. Truly issued an upbeat assessment of the agency's many programs and
said an analysis of future manned missions to the moon and Mars "is
proceeding exceedingly well."

     While the Moon and Mars missions "will be technically demanding and
not without risk, they are well within our reach," Admiral Truly said at a
National Press Club luncheon in Washington, D.C.

     "These expeditions will stimulate new technologies and enhance our
nation's long-term productivity," Admiral Truly said.  "They will improve
national competitiveness.  They will advance scientific knowledge and
lead to discoveries about our solar system, Earth and life, itself."

     The NASA leader's broad-brush review of current NASA programs
included the following highlights:

     * Aeronautics - NASA technology has enabled the U.S. aerospace
industry to maintain "an unqualified lead in world markets."  To help
maintain this position, NASA has revived research on a high-speed civil
transport -- research that will lead to "environmentally sound, supersonic
travel for the future."

     * Space Science - The recent launches of the Galileo and Magellan
space probes ushers in an extraordinary era of space science missions.
Over the next 5 years, NASA will launch 37 space missions that will
"radically change our understanding, not only of the universe but also
of ourselves."

     * "Mission to Planet Earth" - Using "superior new instruments," we can
take a comprehensive look at the entire global system -- lands, oceans,
ice and atmosphere.  This program is taking shape and promises to provide
data that "will be coordinated in a decades-long effort to better
understand our fragile Earth."

     * Space Shuttle - With six successful missions since the return to
flight, NASA is moving confidently to safely increase the Shuttle's flight
rate.  The Shuttle is "unquestionably a far safer and much more reliable
vehicle" and will be critical in the construction of Space Station Freedom.

     * Space Station Freedom - The "cornerstone of our future in  space,"
Freedom is the largest international cooperative space  project ever
undertaken.  It is an essential step toward moving  again beyond Earth
orbit and into the solar system, providing new insights into the human
body and psyche as we cope with longer durations of space flight;
allowing us to test exploration technologies; and permitting the
assembly service of space vehicles.

     Last July 20, the 20th anniversary of the Apollo 11 moon landing,
President Bush committed the United States to return to the moon and
then explore Mars.  NASA is supporting the efforts of the National Space
Council, chaired by Vice President Quayle, to determine what resources
will be required and to set a realistic timetable to meet these goals.

     Admiral Truly said the benefits of future missions to the moon and
Mars are difficult to quantify and include such intangibles as knowledge,
success and pride.  "Each time we go to the frontier and beyond," he said,
"we bring back more than we hoped for.  This time we have the chance to
bring back more than we can imagine."

     He also said manned space exploration will stimulate science and
engineering education in the United States.  "I feel strongly that NASA has
a special responsibility in education for a very special reason.  Our
programs -- airplanes, spaceships, moon, Mars and astronauts -- can get
to kids."

Note:  Copies of Admiral Truly's prepared remarks are available from the
NASA Newsroom, Room 6043, 400 Maryland Ave., S.W., Washington, DC
20546 (phone:  XXX/YYY-ZZZZ).

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

Date: 27 Oct 89 01:46:45 GMT
From: crash!orbit!pnet51![e-mail]  (S Schaper)
Subject: Re: Galileo

And that brings up the question, What sort of computer does it have?
  Inquiring Netaddicts want to know


UUCP: {amdahl!bungia, uunet!rosevax, chinet, killer}!orbit!pnet51!schaper
ARPA: crash!orbit!pnet51![e-mail]
INET: [e-mail]

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

Date: 27 Oct 89 19:42:02 GMT
From: skipper![e-mail]  (Mary Shafer)
Subject: Looking at Atlantis

I just went out to the Mate-Demate Device (MDD) and looked at Atlantis.
(It's 1230 PDT, Friday, 27 Oct)

They've got got it in the MDD and up on jacks.  The gear is retracted
now.  Mating with the 747 Shuttle Carrier Aircraft is scheduled for
about 0200 Saturday morning and they are planning to leave Edwards AFB
at first light, about 0650.  The plan is to stop in San Antonio to
refuel and to arrive at KSC before dark.

When Atlantis was towed down the ramp to the MDD a few hours after the
landing, I thought it looked really clean.  I just confirmed that.
There's almost _no_ scorching.  I wonder if they changed the paint?  I
also heard that only about 50 tiles were damaged.  I didn't see much
damage on Monday.  (I couldn't see much of the tiles today, with the
MDD all around it.)

A bit of trivia: The wind limit on raising the Shuttle in the MDD is 7
knots.  Above that they're restricted to ground level work only.
Also, they hope for zero wind when mounting the tailcone, although
they can tolerate a couple of knots.

--
Mary Shafer   [e-mail]  ames!elxsi.dfrf.nasa.gov!shafer
         NASA Ames-Dryden Flight Research Facility, Edwards, CA
                    Of course I don't speak for NASA

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

Date: 28 Oct 89 05:11:15 GMT
From: uccba!uceng![e-mail]  (daniel mocsny)
Subject: Re: Asteroids as weapons of mass destruction

> In article <[e-mail]> [e-mail] () writes:
> >Take a small spacecraft out to about a light-year, aim it at Earth, and
> > fire theengines.  When it hits, it should have a velocity close to c and
> > would do a lot of damage.

In article <[e-mail]>, [e-mail] (Henry Spencer) writes:
[ ... this won't work because ... ]

> ... a small spacecraft, using any immediate-foreseeable rocket
> technology, will run out of fuel long before it can get anywhere near c.

Yeah, but Henry, think about how long a present-day spacecraft would
take to get out to a distance of one light-year. By the time it gets
out there, drive technology will certainly have advanced enough to let
us do some interesting things. So you just radio out the necessary
software upgrades to the probe to enable it to transform itself into a
Von Neumann Universal Replicator. That could be tough, of course,
because we don't know what sort of hardware/raw materials to put on
board to make this easier. But I would expect the technology of a few
millennia hence to be so advanced that they could probably start with
almost any sort of antique general-purpose computer and manipulator
arm and make it turn itself into anything. If worse came to worst,
some technical enthusiast could turn herself into an "energy being"
and broadcast out directly to install the upgrade.

Dan Mocsny
[e-mail]

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

Date: 29 Oct 89 20:21:56 GMT
From: jarthur![e-mail]  (Mark Wilkins)
Subject: Re: Trying to build a fluxgate magnetometer -- help!

In article <[e-mail]> [e-mail] (Doug McDonald) writes:

>(Also, I might add, a lot of people refer to actual physical
>magnets, though not the fields they create, in megahertz - as
>in "it's a 500 MHz magnet" meaning, of course, that the NMR
>resonance frequency of protons in it would be 500 MHz." Even the
>people who do this snicker a bit while doing it, however.)
>
>Doug McDonald

   Ummm...  In the world of analytical chemistry and in some other areas
where large magnets are often in use the Tesla is used to measure large
fields.  For example, Nicolet Instruments, the company which currently holds
the patent on Fourier transform mass spectrometers, advertises all of their
magnets in Tesla values as do most other manufacturers in the analytical
chemistry market.
   In general, when I was working in analytical chemistry at UC Riverside,
the only place I heard the gauss values used was in the Bank of America's
specification that credit cards were unsafe past the 50 gauss line.  The
magnets were always, to us, thirteen, seven, and three TESLA.
   Of course, everybody also used "torr" to refer to "mm Hg," which people in
some fields would find odd.  I suppose the point is that just because your
area of work has different conventions than someone else's it isn't really
yours to say that some unit or another is NEVER, EVER used.

             -- Mark Wilkins
                [e-mail]

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

Date: 29 Oct 89 23:38:22 GMT
From: kitty![e-mail]  (Larry Lippman)
Subject: Re: Trying to build a fluxgate magnetometer -- help!

In article <[e-mail]>, [e-mail] (Doug McDonald) writes:
> >>I would like to measure changes at least as small as
> >>10 gammas (.001 Gauss), and if possible, even smaller.
> >
> >?  You mean of course, nanotesla (nT), since 1954.  :-)
>
> I have been in the science business for over 20 years and have
> never heard anyone refer to magnetic fields in Tesla - everyone
> uses gauss. It is true that people know that someone somewhere
> created a unit of magnetic field called a Tesla, but no one
> remembers how many gauss are in one Tesla, and no one uses it.
> Sometimes it might appear in a textbook (usually directed at
> freshmen or sophmores - more advanced books use gauss).

    Speaking as a Gauss-person who would prefer to see otherwise :-),
I regret to inform you that the Tesla is indeed being used in the real
world to replace the Gauss as a unit of magnetic flux density measurement.

    Many magnetometer and magnetic instrument manufacturers, such
as F. W. Bell, Humphrey Inc., FRL Industries and Walker Scientific now
use the Tesla instead of the Gauss as their unit of specification.
However, it is somewhat amusing to note that while these vendors still
refer to certain products as "gaussmeters", they are now specified
using the Tesla as a unit of measurement; sort of an oxymoron, huh? :-)

    Since I have already survived and coped with the Pascal, the
change to Tesla was less traumatic than I had imagined.  Incidently,
the nanotesla (nT) seems to have replaced the gamma (.00001 Gauss) where
finer magnetic flux measurements are concerned.

<> Larry Lippman @ Recognition Research Corp. - Uniquex Corp. - Viatran Corp.
<> UUCP  {allegra|boulder|decvax|rutgers|watmath}!sunybcs!kitty!larry
<> TEL [phone] | 716/773-1700  {hplabs|utzoo|uunet}!/      \uniquex!larry
<> FAX [phone] | 716/773-2488      "Have you hugged your cat today?"

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

End of SPACE Digest V10 #190
*******************