Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V16_3/V16NO345.TXT

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Date: Sat, 20 Mar 93 05:39:44
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V16 #345
To: Space Digest Readers
Precedence: bulk


Space Digest                Sat, 20 Mar 93       Volume 16 : Issue 345

Today's Topics:
                         CD for Pluto Mission
             Flight time comparison: Voyager vs. Gallileo
                              Grand Plan
               Just a little tap (was Re: Galileo HGA)
   Lunar Arctic, pressure, antifreeze (was Re: Lunar ice transport)
                      Magellan Update - 03/19/93
                  Our Universe not a party Universe?
         Predicting gravity wave quantization & Cosmic Noise
                Space Station Redesign: Constellation
                     SR-71 Maiden Science Flight
                 SSTO: A Spaceship for the rest of us
                          Water Simulations
                  Why use AC at 20kHz for SSF Power?

    Welcome to the Space Digest!!  Please send your messages to
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----------------------------------------------------------------------

Date: Fri, 19 Mar 1993 21:50:46 GMT
From: Bob Myers <[e-mail]>
Subject: CD for Pluto Mission
Newsgroups: sci.space

Why a CD?  Just because consumer recording technology has moved ahead is
no reason to assume that the CD is a good choice for such a project.  One
of the nicer things about the Voyager record was that it was expected to be
reasonably easy to figure out - easier, I suspect, than trying to understand
the CD format without shipping a tech from Sony along with the thing!


Bob Myers            | "One man's theology is another man's belly laugh."
[e-mail]      |                     - Lazarus Long/Robert A. Heinlein
                     |

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

Date: 19 Mar 93 15:24:02 GMT
From: Pat <[e-mail]>
Subject: Flight time comparison: Voyager vs. Gallileo
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>
>No, the fundamental problem is that Galileo really could have used a
>trip to the fat farm.  Galileo is much, much heavier than the Voyagers,

So what is the cause of Galileos weight problem.  I know , I know it's
a glandular thing :-)  But serious,  what  Extra heavy RTG's, or
fat instruments?  or  spare mass for a locker to jam szabo in,  and
send him off prospecting for materials:-)

pat

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

Date: Sat, 20 Mar 1993 04:57:07 GMT
From: Henry Spencer <[e-mail]>
Subject: Grand Plan
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Ron Baalke) writes:
>>CRAF was cancelled because it had overrun its budget massively, and Congress
>>was giving clear signals that this would not be tolerated...
>
>CRAF/Cassini did not overrun its budget...

NASA proposed to do both for $1.6G.  By the time CRAF died, Cassini alone
was going to cost that much (and Congress had been very clear that it had
priority over CRAF).  "The Space Studies Board has found the cost growth
in the Comet Rendezvous Asteroid Flyby and Cassini program to be very
frustrating and difficult to understand." -- Louis Lanzerotti, chairman
of NRC's Space Studies Board, phone interview by Space News (quoted in
the March 1 issue).

It's true that a certain amount of Congressional fiddling contributed
*somewhat* to this, but when the SSB's chairman says he doesn't know why
the costs ballooned the way they did, I have a strange suspicion that
he's allowing for the known causes.
--
All work is one man's work.             | Henry Spencer @ U of Toronto Zoology
                    - Kipling           |  [e-mail]  utzoo!henry

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

Date: Sat, 20 Mar 1993 04:44:15 GMT
From: Henry Spencer <[e-mail]>
Subject: Just a little tap (was Re: Galileo HGA)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Pat) writes:
>Um Nick,  How does a 1,000 fold loss of Data transmission capacity, that
>was fully booked, condense to only a 30% loss of Mission? ...

By a combination of a lot of sweating on data compression and improved
receiver hardware, plus some fairly drastic changes in operational plans,
plus drastic cuts in some of the more imaging-intensive efforts.  That
30% isn't across the board, it's heavily concentrated in the more
data-intensive parts of the mission, notably the atmosphere imaging.
(The moon flybys aren't getting hit all that badly, because while they
are very imaging-intensive, they're also brief with long waiting periods
in between, so they lend themselves to taping the images and then slowly
dribbling the data back to Earth between encounters.)

I'm sure the best possible face has been put on the numbers for PR use --
any number like that is mostly for PR anyway, since you can't weigh science
results like that -- but if you aren't an aspiring Jupiter meterologist,
the problem is, if not solved, at least under control.
--
All work is one man's work.             | Henry Spencer @ U of Toronto Zoology
                    - Kipling           |  [e-mail]  utzoo!henry

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

Date: Sat, 20 Mar 1993 04:38:00 GMT
From: Henry Spencer <[e-mail]>
Subject: Lunar Arctic, pressure, antifreeze (was Re: Lunar ice transport)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Bill Higgins-- Beam Jockey) writes:
>Remember Henry's assertion that the temperature is a constant 255 K
>underground?  That nice steady thermal environment is mighty
>attractive.

Note that that's at a depth of 1m.  Our measurements go down only 2-3m
(and go down that far at only one site -- it took until Apollo 16 to
sort out the problems of drilling holes in the regolith, and then John
Young had to trip over the damn cable, so our only deep data is from
Apollo 17...), but it looks like the temperature rises at something
like 1.3K/m.  You might not have to bury the thing all that deeply
to get above 0C.

Of course, going down (say) 15m is still a *lot* more excavation...
and lunar excavation is a pain, the regolith is just dust but it's
packed down **HARD**.  You'll also start hitting big rocks at some
ill-defined depth where the regolith ends and mega-regolith begins.
--
All work is one man's work.             | Henry Spencer @ U of Toronto Zoology
                    - Kipling           |  [e-mail]  utzoo!henry

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

Date: 20 Mar 1993 02:58 UT
From: Ron Baalke <[e-mail]>
Subject: Magellan Update - 03/19/93
Newsgroups: sci.space,sci.astro,alt.sci.planetary

Forwarded from Doug Griffith, Magellan Project Manager

                       MAGELLAN STATUS REPORT
                           March 19, 1993

1.  The Magellan spacecraft is operating normally, performing a desat
(desaturation of the reaction wheels) on every orbit and a starcal
(star calibration) every other orbit.  The High Gain Antenna is kept
pointed toward Earth (except during the starcal) in order to acquire
gravity data, especially around periapsis.  Engineering telemetry is
being received at 1200 bps.

2.  The Magellan Project continues to implement the plan to collocate
50 MESUR (Mars Enviromental Survey project) members on the second floor
of Bldg. 230, while minimizing impact to MGN preparations for TEX
(Transition Experiment) and LMGT (Lean Mean Gravity Team).  About half
of the offices being vacated by MGN team members have been cleared, and

the remaining moves will be complete by March 31st.  Significant amounts
of excess paper have been eliminated, and unneeded equipment has been
surplused.

3.  Several members of the Magellan science team were in Houston,
Texas, this week for the Lunar and Planetary Science Conference.  An
Exhibit of Magellan results was presented, as well as technical
papers.

4.  Magellan completed its 7000 orbit of Venus shortly before midnight
(PST) on Tuesday.  We are now 67 days from the end of Cycle-4 and the
start of the Transition Experiment.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Don't ever take a fence
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | down until you know the
|_____|/  |_|/       |_____|/                     | reason it was put up.

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

Date: 20 Mar 1993 09:15:16 GMT
From: Zdzislaw Meglicki <[e-mail]>
Subject: Our Universe not a party Universe?
Newsgroups: sci.astro,sci.space,sci.physics

In article <[e-mail]>, [e-mail] (John S. Neff) writes:
|> In article <[e-mail]> [e-mail] (Jeff Bytof) writes:
|> >From: [e-mail] (Jeff Bytof)
|> >Subject: Our Universe not a party Universe?
|> >Date: Fri, 19 Mar 1993 02:12:01 GMT
|> >In article <[e-mail]> [e-mail] (Dave Palmer) writes:
|> >
|> >>Those of us who grew up reading science fiction have become comfortable
|> >>with the idea of rapid space travel via some sort of "space warp." That
|> >>is, a technology for warping space or passing through wormholes,
|> >>hyperspace, or whatever. I think we've just tended to assume that someday
|> >>we will discover how to do this. But what if no such mechanism is
|> >>possible? Or, if it is, but requires impractical energies, or has some
|> >>other practical limitation?
[...]
|> A practical problem, seldom covered in science fiction stories
|> about traveling at near the speed of light, is the radiation hazard.
|> If we assume v = 0.9c and N = 1 hydrogen atom per cc for an average
|> density in interstellar space the flux of ~ 100 MeV protons will
|> be about 2e10 per sq cm of effective area of spacecraft. Hardening
|> equipment to work under such conditions will be a big challenge, and
|> keeping people alive will be even more difficult.

I strongly suspect that we're doomed never to try interstellar travel
in our current form. If our civilisation is ever to spread it may happen in
an altogether different way: durable, intelligent robots travelling from
one star to another at pretty unimpressive speeds (but, what's 10,000 years for
a machine in vacuum, the more so if it can switch itself off to save
its power sources). We're just the "missing link", or, if you prefer,
"cosmic larvae".
--
   Zdzislaw Gustav Meglicki, [e-mail],
   Automated Reasoning Program - CISR, and Plasma Theory Group - RSPhysS,
   The Australian National University, G.P.O. Box 4, Canberra, A.C.T., 2601,
   Australia, fax: (Australia)-6-249-0747, tel: (Australia)-6-249-0158

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

Date: Sat, 20 Mar 1993 03:15:30 GMT
From: Cameron Randale Bass <[e-mail]>
Subject: Predicting gravity wave quantization & Cosmic Noise
Newsgroups: sci.space,sci.astro,sci.physics,alt.sci.planetary

In article <[e-mail]> [e-mail] (Mark) writes:
>In article <[e-mail]> [e-mail] (Cameron Randale Bass) writes:
>>     Not really wishing to start another discussion on what the 'speed'
>>     of gravity means, if the waves travelled instantaneously, how
>>     does one define or detect a 'wave'?
>
>I believe that the universe is closed.  That means that all functions are
>decomposeable into a series of harmonics with respect to the closed dimensions.
>I believe that the metric has components at low frequencies that are residual
>from the Big Bang.  They will occur as standing waves, so the idea of wave
>speed is utterly inappropriate.

     Ignoring the fact that you're talking about standing waves of
     tremendous spatial extent (and ignoring that wavespeed can be
     perfectly well defined in systems with standing waves),
     your coefficients are changing with time (since you
     apparently believe in some sort of 'Bang').  Have you
     worked out the havoc this is going to cause with your 'standing waves'?

>Since there's closure in the spatial dimensions, these components will only
>exist at discrete values of wavelength and frequency, which (doing a back of
>the envelope calculation) comes out to something on the order of a millimeter
>separation for wavelengths of 1 AU (wavelength^2 / universe radius).
>
>If the spacecraft are separated far enough (like by more than 1 AU) you could
>detect these components because it's like you'll have a huge antenna detecting
>them.  Having more than one spacecraft is crucial in order to triangulate.

     Okay, we're bathed in such 'waves', right?  At what amplitude,
     and how will it affect the spacecraft?  With a wavepacket of
     limited temporal extent, you  presumably see the 'whack'.
     What you're asking for is a constant vibration at all
     three satellites and the ground station.  How does one
     distinguish this from 'noise'?

     And how in the blazes do you propose 'triangulating' a standing wave?
     What does that even mean?

                             dale bass


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

Date: Sat, 20 Mar 1993 08:10:24 GMT
From: Nick Szabo <[e-mail]>
Subject: Space Station Redesign: Constellation
Newsgroups: sci.space

Let's step back and consider the functionality we want:

[1] microgravity/vacuum process research
[2] life sciences research (adaptation to space)
[3] spacecraft maintenence

The old NASA approach, explified by Shuttle and SSF, was to
centralize functionality.  These projects failed to meet
their targets by a wide margin: the military and commercial users
took most of their payloads off Shuttle after wasting much effort to
tie their payloads to it, and SSF has failed in a jumble of disorganization
and miscommunication.  Over $50 billion has been spent on these
two projects with no reduction in launch costs and no improvement
in commercial space industrialization.  Meanwhile, military and commercial
users have come up with a superior strategy for space development: the
constellation.

Firstly, different functions are broken down into different
constellations placed in the optimal orbit for each function:
thus we have the GPS/Navstar constellation in 12-hour orbits,
comsats in Clarke and Molniya orbits, etc.  Secondly, the task
is distributed amongst several spacecraft in a constellation,
providing for redundancy and full coverage where needed.

SSF's 3 main functions require quite different environments
and are also prime candidates for constellization.

[1] We have the makings of a materials processing constellation
now: COMET and Mir for long-duration flights, Shuttle/Spacelab for
short-duration flights.  The best strategy for this area is
inexpensive, incremental improvement: installation of U.S. facilities
on Mir, Shuttle/Mir linkup, and transition from Shuttle/Spacelab
to a much less expensive SSTO/Spacehab/COMET or SSTO/SIF/COMET.
We might also expand the research program to take advantage of
interesting space environments, eg the high-radiation Van Allen belt
or gas/plasma gradients in comet tails.  The COMET system can
be much more easily retrofitted for these tasks, where a
station is too large to affordably launch beyond LEO.

[2] We need to study life sciences not just in microgravity,
but also in lunar and Martian gravities, and in the radiation
environments of deep space instead of the protected shelter
of LEO.  This is a very long-term, low-priority project, since
astronauts will have little practical use in the space program
until costs come down orders of magnitude.  Furthermore, using
astronauts severely restricts the scope of the investigation,
and the sample size.  So I propose LabRatSat, a constellation
tether-bolo satellites that test out various levels of gravity
in super-Van-Allen-Belt orbits that are representative of the
radiation environment encountered on Earth-Moon, Earth-Mars,
Earth-asteroid, etc. trips.  The miniaturized life support
machinery might be operated real-time from earth thru a VR
interface.  AFter several orbital missions have been flown,
follow-ons can act as LDEFs on the lunar and Martian surface,
testing out the actual environment at low cost before $billions
are spent on astronauts.

[3] By far the largest market for spacecraft servicing is in
Clarke orbit.  I propose a fleet of small teleoperated
robots. Ground engineers can practice their skills on the
many defunct satellites in Clarke and super-Clarke orbit
before trying them out on real cases.  Once in place, robots can
pry stuck solar arrays and antennas, attach solar battery power packs,
inject fuel, etc.  Once the fleet is working, it can be
spun off to commercial company(s) who can work with the comsat
companies to develop comsat replaceable module standards.

By applying the successful constellation strategy, and getting
rid of the failed centralized strategy of Shuttle and SSF, we
have radically improved the capability of the program while
greatly cutting its cost.  For a fraction of SSF's pricetag,
we can fix satellites where the satellites are, we can study
life's adaptation to a larger & more representative variety
of space environments, and we can do microgravity and vacuum
research inexpensively and, if needed, in special-purpose
orbits.  In this constellation strategy lie also the seeds of
two potential U.S. export industries: affordable space materials
processing and satellite servicing. The key is lowering the
cost of capability to the point where the commercial market
is large and profitable without further NASA intervention.
The centralized-station strategy has demonstrated just
the opposite, cost hikes and capability cuts, and has thus
demonstrated its inability to foster new space industries.

N.B., we can apply the constellation strategy to SEI as well, greatly
cutting its cost and increasing its functionality.  MESUR and
Artemis are two good examples of this; more ambitiously we can
set up a network of native propellant plants on Mars that can be used
to fuel planet-wide rover/ballistic hopper prospecting and
sample return.  The descendants of LabRatSat's technology can
be used as a Mars surface LDEF and to test out closed-ecology
greenhouses on Mars at low cost.  The decentralized strategy
also allows concurrent exploration & development of the moon,
asteroids, Jupiter-family comets and Mars. We can pick favorites
based on actual discoveries when we make them, instead of being
forced to make an initial choice, and putting all our eggs in
one very expensive planetary basket which may turn out to be
barren.


--
Nick Szabo                     [e-mail]

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

Date: Fri, 19 Mar 93 23:41:28 PST
From: Mark Robert Thorson <[e-mail]>
Subject: SR-71 Maiden Science Flight
Newsgroups: sci.space

>     The SR-71 can take measurements across a wider area at that
>     height, it can also take measurments in day, night and terminator
>     between day/night all in 1 flight, i.e. within a short period of
>     time. This wide sample space may provide useful information beyond
>     what a balloon's sample space would be.

But what if you used TWO balloons, or maybe three.  That would solve the
sample space problem at much lower cost.

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

Date: Sat, 20 Mar 1993 04:28:11 GMT
From: Henry Spencer <[e-mail]>
Subject: SSTO: A Spaceship for the rest of us
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Steinn Sigurdsson) writes:
>   Second, and more serious, I quoted LOX at five **CENTS** a pound, not
>   five dollars a pound.
>
>Got a source for that number? You can't get drinking water for 5c/lb
>in most places! ...

The source is Max Hunter, who knows more than a little about launchers
and launcher economics...

For those unfamiliar with the name, Hunter was chief engineer for Thor,
which eventually became Delta, and is the father of the current SSTO
project.  Much of my technical-issues writeup was based on his "The SSX:
SpaceShip Experimental", revised draft, 11 March 1989.  (Please don't
ask where you can get a copy -- I don't know.)
--
All work is one man's work.             | Henry Spencer @ U of Toronto Zoology
                    - Kipling           |  [e-mail]  utzoo!henry

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

Date: Sat, 20 Mar 1993 04:20:16 GMT
From: Bruce Dunn <[e-mail]>
Subject: Water Simulations
Newsgroups: sci.space

> Henry Spencer writes:
>
> There are two things really wrong with the water-tank simulation of free
> fall.  One is that you are lying in your suit rather than floating in it.
> The other is the more obvious issue:  the water has viscosity.


        I once again offer my suggestion of a neutral buoyancy simulator
using pentane rather than water for buoyancy.  Pentane has only a small
fraction of the viscosity of water.  There are obvious problems with
operating such a facility (previously hashed over in this group), but I am
not convinced that there are any show stoppers.
       Yesterday I spent several minutes in semi-darkness in 110 feet of
water at 8 C, with my body tissues rapidly loading with dissolved nitrogen as
I breathed air from a system which inherently has a number of single point
failure modes.  I enjoyed it thoroughly - I was sport diving on SCUBA.
However, although this was a routine dive I probably would have been a lot
safer if I was in a spacesuit submerged in 10 feet of pentane, with safety
personnel watching every move and standing by to haul me out at the first
sign of trouble.
--
Bruce Dunn    Vancouver, Canada   [e-mail]

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

Date: Sat, 20 Mar 1993 07:27:31 GMT
From: "Richard A. Schumacher" <[e-mail]>
Subject: Why use AC at 20kHz for SSF Power?
Newsgroups: sci.space

>One of the most frequent complaints here against NASA is that
>they don't consider new technologies that might lower costs
>in the long run and don't experiment with different concepts.
>Yet, when they do and it doesn't work out they are chastised
>(often by the same people) for wasting money when they could
>have been using old and tried technology, and using the
>magic of 20-20 hindsight it becomes "obvious" that the
>new concept tried wouldn't work.
>Pah!

The problem is that NASA hasn't had decent experimental technology
programs for years. They attempt to turn all new technology into
an operational system all at once without allowing for necessary
development time. Notice how well that worked with the shuttle.
The twin points are: if you want to build an operational system
with minimum cost and risk, use existing technology. If you
want to develop new technologies, run experimental programs.
If you're serious about what you're doing, you do both in
tandem. One should not have to figure out how to dry lumber and
make nails while building the house.


>Those [scientific] instruments are handbuilt at no small expense.

Thank you for making my point! Handbuilt, unique, non-standard
stuff, like 20 kHz power systems and things to plug into them,
are expensive. 10 years from now, after 10 years of development
effort, 20 kHz power systems might be cheap, reliable and the
right choice. For something that was originally intended to
fly last year, they're not. Go out and buy something else.

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

End of Space Digest Volume 16 : Issue 345
------------------------------