Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V13_4/V13_401.TXT

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Subject: SPACE Digest V13 #401

SPACE Digest                                     Volume 13 : Issue 401

Today's Topics:
            Re: Launch Technology
               Re: Magellan Aerobraking
        Re: comsat cancellations and lawsuits
     Voyager CD-ROM 4 replaced with Magellan MIDR CD-ROM
               Re: Upper Stage
            Re: Launch Technology
             Re: I want to go to orbit...
             Re: Space technology
          Amiga satalight tracker data file
        Re: Teflon (Was Re: Space technology)
         Re: NEP to Mars!?!? - a thesis topic

Administrivia:

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

Date: 12 Apr 91 15:56:38 GMT
From: usc!rpi!news-server.csri.toronto.edu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Launch Technology

In article <[e-mail]> [e-mail] (Chris Jones) writes:
>don't know whether this is really plain old kerosene or their RP-1 equivalent,
>but the difference probably isn't that great.

Probably zero.  RP-1 *is* high-grade kerosene, and "kerosene" can be used
as a generic term for it and similar fuels.
--
And the bean-counter replied,           | Henry Spencer @ U of Toronto Zoology
"beans are more important".             |  [e-mail]  utzoo!henry

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

Date: 11 Apr 91 00:13:38 GMT
From: hub.ucsb.edu!ucsbuxa![e-mail]  (Charles Frank Radley)
Subject: Re: Magellan Aerobraking



Magellan 's original orbital u insertion was by means of
a Thiokol Star-48 solid motor, which weighed more than
the rest of the spacecraft.   It has no heat shield.
I have heard of a plan to do some sdm low energy aerobrking
to modify its orbit.   This will presumably cause the
spacecraft to become significantly heated, and I have
hear Magellan is already encountering themral problems..

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

Date: 12 Apr 91 16:31:04 GMT
From: agate!bionet!uwm.edu!linac!pacific.mps.ohio-state.edu!zaphod.mps.ohio-state.edu!rpi!news-server.csri.toronto.edu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: comsat cancellations and lawsuits

In article <[e-mail]> [e-mail] (Charles Frank Radley) writes:
>  NASA never guaranteed to launch anything.
>The language in the standard Launch Services Agreement
>states NASA will use "their best endeavours", which
>means no warranty etc.

Still sounds like grounds for a lawsuit to me.  *What* "best endeavours"?
More like "we'll launch it if it's convenient, but at the first sign of
trouble, forget it".
--
And the bean-counter replied,           | Henry Spencer @ U of Toronto Zoology
"beans are more important".             |  [e-mail]  utzoo!henry

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

Date: 13 Apr 91 01:56:13 GMT
From: [e-mail]  (Peter E. Yee)
Subject: Voyager CD-ROM 4 replaced with Magellan MIDR CD-ROM


Thanks to Rob Seaman at NOAO, I have a patch for my Sun HSFS driver that allows
it to read the Magellan discs.  The images on the Magellan disc appear to
be larger than the Voyager images and are not compressed.  The images are
available via anonymous ftp to ames.arc.nasa.gov, and are mounted on the
/pub/SPACE/CDROM2 directory (replacing the Voyager CD-ROM 4 that I had
installed yesterday).

                        -Peter Yee
                        [e-mail]
                        ames!yee

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

Date: 12 Apr 91 04:46:20 GMT
From: swrinde!elroy.jpl.nasa.gov!zardoz.cpd.com!dhw68k!ofa123![e-mail]  (Wales Larrison)
Subject: Re: Upper Stage

Nick Szabo replying to message from Paul Blase
>Hold on.  If a market doesn't exist, why are you building the thing
>in the first place?  A government is the poorest judge of markets I
>can think of, bar none.
 >
> I can think of jillions of examples of this, but right off the bat
>there is one that hit close to home: upper stages.  In the dozens
>government studies of nuclear, electric, and other advanced upper
>stages I have read, use for boosting satcoms to GEO is rarely, if
>ever, mentioned, even though this is by far the largest use of
>upper stages.  ...
  Sorry, but I couldn't resist replying to this. Boy, are you wrong.
What if the the government is the market?  Let's see - most commonly
used upper stages are:
  - PAM-D, developed by McDonnell Douglas to launch government
payloads (GOES and other geo satellites).  Exclusively used for GEO
launches.  Commercial development, under government license.  Money
loser to date.  Government usage estimated at approx 40%
  - IUS, developed by Boeing under USAF contract.  Used to launch
government payloads, and TDRS (operated by commercial entity for
government use, with excess capacity being sold on the open market).
2(?) uses for non-GEO missions by NASA.  Remaining 20+ uses for GEO.
  - Centaur, developed by General Dynamics under government
contract.  Minor/slight upgrades paid for by commercial entities.
Major upgrades paid for by government for GEO missions.

  - TOS, developed by OSC.  Only 2-3 uses are for NASA. Money loser.
  Almost every government upper stage study I have seen in the last
decade has had GEO as a major market.  The market to GEO is split
about 40/60 between Commercial satellites and government satellites
(including GPS in the government market).  Government studies of
upper stages do focus on GEO, since the majority of high altitude
government payloads go to GEO, or very close.
  The exceptions are specific studies which examine how to meet a
unique government launch requirement - well outside of the
commercial requirements.  For example - launching 100,000 lbs into
Low Lunar Orbit usually requires a system which has little
application to 2,000 lb commercial GEO satellites.

>Meanwhile, Rocket Research Company and OSC, with no help from the
>government, have teamed up to finally bring electric technology to
>the market where it is needed most, satcom stationkeeping and upper
>stages. ...
   Ahem.  Rocket Research is developing arc-jet thruster systems
under USAF contract.  Their effort is part of the ELITE ("Electric
Insertion Transfer Experiment") program from the USAF Phillips Lab
in New Mexico to demonstrate an electric GEO transfer upper stage.
Prime contractor for the USAF is TRW.  Rocket Research is providing
the arcjet, power conditioning, and propellant feed unit.
   In all fairness, RR is also developing a de-rated system of
potential application to commercial spacecraft.  However, my files
say the primary focus of this system is to provide stationkeeping on
comsats, not act as an electric stage.  I would suspect a lot of the
technology development for this was done under the USAF contract.
  Considering also that OSC is also under USAF contract to build and
fly the APEX Advanced Photovoltaic and Electrics Experiments
spacecraft, it sure looks to me like the USAF is supporting the
development of any future commercial applications of this by funding
all of the R&D, development and design work ...
  I think you're flaming here, Nick.


--
Wales Larrison
Internet: [e-mail]
Compuserve: >internet:[e-mail]
--------------------------------------------------------------------------

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

Date: 12 Apr 91 14:55:19 GMT
From: eru!hagbard!sunic!mcsun!hp4nl!phigate!philtis![e-mail]  (Harm Munk)
Subject: Re: Launch Technology

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>I've never seen a discussion of the exact rationale for Ariane's fuel
>combination, but remember another consideration:  the Ariane contractors
>were military missile contractors, whose experience with liquid-fuel
>rockets would have been heavily biased toward storable fuels.  It would
>not surprise me if the decision was made based on what people had experience
>designing engines for, rather than on the merits of the fuels themselves.
>Engine development is often the pacing item for launcher development.

Well, I don't know about the design of Ariane 4 engines, but for the
boosters for Ariane 5 they certainly did a 'go-for-the-best-you-can-get'
type of research. On the other hand ... that research was performed by a
research institute of the Dutch Organisation of Applied Scientific
Research (TNO for insiders) which usually does military research (the
institute, that is, not TNO in general).

Anyway, if you want to know the rationale behind the Ariane 5 boosters,
read ESA Journal 1990/3.


Regards,
    Harm Munk.

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

Date: 10 Apr 91 00:13:18 GMT
From: hub.ucsb.edu!ucsbuxa![e-mail]  (Charles Frank Radley)
Subject: Re: I want to go to orbit...



Truax is in southern California, developing a small sea
launched recoverable rocket for the US Navy, on a substantial
contract - a couple of $M

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

Date: 12 Apr 91 06:58:55 GMT
From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!mips!spool.mu.edu!munnari.oz.au!manuel!coombs![e-mail]  (Chris @ SSDA ...)
Subject: Re: Space technology

[e-mail] (Phil OKunewick) writes:

>In article <[e-mail]> [e-mail] (Robert W Murphree) writes:

>   Lots of stuff about frypans etc deleted...


>   One space spin-off was directly related to geology (and hey, this
>_is_ cross-posted to that newsgroup): 4.5 million-year-old moon rocks.
>These showed that the earth and moon formed at the same time, and thus
>partly settled one of the greatest disputes in geoscience.  From this,
>we were able to develop a better theory on how the solar system
>formed.  Although at first this doesn't seem nearly as useful as a
>non-stick frying pan, the amount it has helped us understand the world
>around us (and thus help preserve it) is incalculable.

    I thought that the earth-moon configuration was caused via the
collision of the moon onto the earth, which caused the melting of both
objects, etc...  I saw a simulation done on a cray which showed this...

Actually I know very little about this theory, anyone got any more info about
this ???

Thanks
  Chris.

PS. I'm not crossposting to Geology ;-)

--
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
                  Chris Patterson | Ph:  [phone]
     Social Science Data Archives | AARNet: [e-mail]
   Australian National University | "I wonder what happens if I ..."

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

Date: 11 Apr 91 17:13:13 GMT
From: eru!hagbard!sunic!mcsun!ukc!strath-cs!str-va![e-mail]  (Dan Dare)
Subject: Amiga satalight tracker data file

I don't normal read this conferance so if you are replying to this message
could you please email me.

I have a program for the amiga called ORBIT it tracks satalights round the
earth and reports on their position so that they can be observed I am given to
understand that the data file with them is updated every 2 weeks if this is so
where would I find the file.

the name of the author escapes me right now but I know he was from the east
cost of america.

If you know where I can find this data or know how to change it inside the
program please let me know.
--
                              / / The Light of the
Dan Dare                      \\  New Dawn Burns Bright
                               /  Even at night.
================================================================================
 AKA  Sean Stratton     | "I came here to chew        | Live life    |Amiga  ///
[e-mail]| bubblegum and kick ass. and | Taste Death  |   \\\///
on JANET                | i'm all out of bubblegum."  |              |    \XX/
================================================================================
               All misspelling is my brains fault not mine

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

Date: 12 Apr 91 16:59:39 GMT
From: media-lab![e-mail]  (Marvin Minsky)
Subject: Re: Teflon (Was Re: Space technology)

In article <[e-mail]>
[e-mail] writes:
>The trick in making non-stick frying pans is to get
>the pan to stick to Teflon as *nothing* sticks to Teflon!!

O.K., I give up.  What's the trick.

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

Date: 10 Apr 91 05:18:12 GMT
From: unisoft!fai!sequent!crg5![e-mail]  (Nick Szabo)
Subject: Re: NEP to Mars!?!? - a thesis topic

In article <[e-mail]> [e-mail] writes:
[needs background profile for nuclear electric propulsion/radiator paper]

An excellent choice of technology, but you are making a big mistake:
tying such a promising technology to one narrow mission.  Mars is
one interesting body out of dozens, and planetary exploration is
one important space endevour out of several.

The biggest market for NEP is as an upper stage for the $billions of
satellites that are currently launched for defense, communications,
and other uses including planetary exploration.  A good design will cut the
amount of mass needed for an upper stage, thereby increasing the mass
that can be put in the payload.  For example, (to pick a number out of
the blue), if you could design an upper stage to double the mass to
GEO for the same launcher, you could sell your upper stage for at least
5 times the price of the competitive chemical stage for that launcher,
because you are effectively saving the entire price of a launch to GEO.
The market for such a technology would be at least $1 billion a year,
perhaps closer to $3 to $4 billion at saturation.

Until we get standard payload bays, upper stages will tend be specific to
certain rockets, so you have to pick the winners.  The best bets at this
point are Titan IV/Shuttle at the high end (where many of the political $$
are), Ariane and/or Delta at the middle end (where most of the commercial
$$ are),  and perhaps Pegasus, a low-end launcher with a new, rapidly
growing market and so far lacking an upper stage.   It would be quite
fascinating, and a true technological advance, to see a nuclear upper
stage made for a Pegasus.


>                     My Tentative Thesis Outline (4/2/91)
>
>I. Background
>      A. Inevitability of deep space missions/exploration

Something, almost inevitably, as there are 4 nations (counting Europe as
one) that have explored the Moon or farther, with over 50 deep space missions
so far, and the technology is getting better every year.  The actual targets,
discoveries, instruments, and scale of mission depend on previous discoveries
and (alas) politics and tradition.


>      B. Problems/parameters of deep space missions
>            1. Mission length
>                  a. Life Support

Only for manned missions, which, with current levels of technology,
are politically and economically untenable beyond LEO.


>....
>                  c. Fuel availability or lack thereof

It is possible that small comets could be captured and used as
reaction or heat sink mass.  H, C, O, and N in various molecules can
all be readily distilled.  For example water, the most abundant comet
molecule, can be used for liquid droplet radiators.   For sufficient
demand (1,000+ tons/year) the price might be $10-$100/kg, a factor of 100 to
1,000 below the costs of hauling up from earth.  Unfortunately, the mission
profile is not rigorous at this point, due to lack of sufficient astronomical
knowledge at this point in space exploration. We don't know how to detect
most small comets, even those that pass near earth.

Other suggested sources of materials (such as the Moon) contain much less
diversity (eg no H, N, or C on Moon) and are much harder to extract (rock
instead of ice mining).  These are economically untenable for any sort of
science or exploration, though asteroids might be used for large-payoff
industrial projects, such as solar power satellites.  In sum, I would take
cometary materials into consideration in your designs, but I would
not count on them in the near future.


>      C. Need for reduction in time and/or fuel required.

Most deep space missions benefit from higher Isp, but there are
specific regimes where decent thrust is also required.   You
might want to look carefully at the thrust requirements to
get a payload to GEO in a decent amount of time.  I had heard
that current electric designs have too low thrust for this (comments?).
I know OSC and Rocket Resarch are looking at chemical/electric
hybrids for this purpose.  Remember, GEO is the most frequent
destination for payloads needing upper stages.


>      E. Mars as example
>            1. Why? due to database available for comparison

Because it was in Collier's.  It's The Plan.  Of course, nobody has
stepped up to pay for anything more than Mars Observer in 1992.

There are some good scientific and exploration reasons to continue
to look at Mars:

* search for life (though it is more probable on Europa and Enceladus)
* fruitful comparisons between Martian and earth weather
* geology (eg search for intersting ore-forming processes)

None of this justifies spending $billions, though, not to mention
the fantastic $400 billion NASA proposed pricetag.

Some non-reasons for exploring Mars are:

* colonization: Mars is quite inferior to near-earth free space in terms
  of time, energy, material availability, ability to trade products
  with earth, and a whole host of other factors.
* prestige:  1990's economic war politics are quite different from
  1960's cold war politics.   In the 1960's, prestige came from
  seeing who could launch the largest payloads into space on
  ICBM derivatives.  Such spectaculars win propaganda wars but
  lose economic wars.  Economic prestige comes from displaying a
  quality, automated, cost-effective, and customer-driven operation.
  If we can learn to operate in this matter, we may be able to
  derive some post-Cold-War era prestige from space exploration.  The
  bulk of our space program still thinks it's living in the 60's,
  alas.



>            2. Any specific Mars problems/advantages over other deep space
>               scenarios?

A rough order of difficulty, in terms of energy, for the larger bodies is
Moon, Venus, Mars, Jupiter, etc.   Gravity assist and aerobraking can
be used, eg Voyager and Galileo VEEGA gravity assist trajectories, and
Apollo aerobraking on the return trip from the Moon.   VEEGA trades time
for energy, though Voyager gained both time and energy.  There exist a few
discovered, and probably 100,000 undiscovered, asteroids closer energy-wise
to LEO than the lunar surface.  There probably an even greater number of
comets, which can be captured via gravity assist and aerobraking, but as
mentioned our astronomical resources are not currently sufficient for the
task of finding and tracking these dark objects.




--
Nick Szabo            [e-mail]
"If you want oil, drill lots of wells" -- J. Paul Getty
The above opinions are my own and not related to those of any
organization I may be affiliated with.

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

End of SPACE Digest V13 #401
*******************