Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V13_3/V13_364.TXT

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Subject: SPACE Digest V13 #364

SPACE Digest                                     Volume 13 : Issue 364

Today's Topics:
              Re: SPACE Digest V13 #344
         Re: NY Times Article: Nuclear rocket
              Re: "Face" on Mars
         Re: Nova: The Dark Side of the Moon
              Re: How 'bout them Titans?
         ESA's space science dept participates in GRO
           Re: Chemical rocket complexities

Administrivia:

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

Date: 4 Apr 91 17:02:38 GMT
From: orca!bambam![e-mail]  (Bob Pendleton)
Subject: Re: SPACE Digest V13 #344

In article <[e-mail]>, [e-mail] (Tom McWilliams) writes:
> Re;  Railguns, EM launchers
>

> Use a short rail, with moderate acceleration to put a fully-loaded, already-
> been-tested-and-budget-approved chemical rocket moving up at around, say,
> 300mph, then fire the rockets.

Good Idea.

> The fact that I can think of this, yet find no reference of the combination of
> similar technologies to yeild better launch efficiencies elsewhere, is my proof
> that the chemical rocket is not streched to it's limits, or fully explored.
> BTW:  That's a ditto for EM, Rail, Hotol, Reusability, etc.

You must not have read the same science fiction I did. Bob Heinlein
used this idea alot in his stories. I think "Space Cadet" was the
first place I remember reading about it.

The "short" rail ran up the west side of Pike's Peak. The rocket
planes sounded like scaled up X-1s with swept wings. The Great Plains
served as a great place to ditch if the engines didn't fire.  And, of
course, being an early Heinlein juvy (don't ever lie to kids!) you can
bet that there was a solid engineering and mathematical basis for
believing that it would work.

One of the reasons I don't think chemical rockets have topped out is
that ideas like this one have been around, and practical, since the
1930s and know one has even tried them.

A little editorializing:

One of my favorite Heinlein quotations says that if it isn't
mathematics it's opinion. What is missed by what he said is that it is
so easy to use pretty fancy looking pseudo mathematics to justify
almost any opinion.


> P.S>  I think chemical rockets will never, ever, have a market outside of LEO.
>       My personal favorites are the ion rocket and solar sail.

I agree that chemical rockets haven't much future beyond LEO. But I'm
rather fond of fission torch rockets myself. I want to get there NOW,
not next year. :-)


> Tommy Mac          I sure hope I get to see if I'm right!
> 18084tm@msu
> Acknowledge-To: <18084TM@MSU>

--
              Bob Pendleton, speaking only for myself.
   [e-mail] or decwrl!esunix!bpendlet or utah-cs!esunix!bpendlet

                         Tools, not rules.

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

Date: 4 Apr 91 17:49:52 GMT
From: orca!bambam![e-mail]  (Bob Pendleton)
Subject: Re: NY Times Article: Nuclear rocket

In article <[e-mail]>, [e-mail] (Raymond Lister) writes:
>

> >Article xxx of clari.tw.space: [cross refed to several clari news groups]
> >From: [e-mail] (ELIOT BRENNER)
> >Subject: Nuclear rocket being developed
> >Date: 3 Apr 91 15:31:24 GMT
>
>     WASHINGTON (UPI) -- The Pentagon is trying to build a nuclear-powered
> rocket to boost huge payloads, satellites or weapons into space,
> scientists and government sources said Wednesday.
>     Rather than using conventional chemical rocket fuels to generate a
> blast of hot gases to propel a rocket into space, the project involves
> vaporizing liquid hyrdogen into a far stronger exhaust stream by passing
> it over a bed of nuclear fuel pellets generating heat as high as 3,000
> degrees.

Well, if they are going to try this kind of foolishness at least the
pellet bed reactor is the right one to use.

In a pellet bed reactor the fuel is sealed up inside lots of small
ceramic marbles. If one pellet fails you get a very small amount of
very nasty stuff coming out the nozzle. In something like the NERVA
reactor if you have a fuel element failure you could get the whole
reactor core coming out the tail.

If one pellet fails you don't lose the structural integrity of the
whole core. Aside from the bucket, a bucket of marbles doesn't have
any structural integrity.

In a crash you, hopefully, get lots of solid pellets scattered
arround.  Easy to find pellets that can be collected. A graphite core
NERVA style reactor could burn and spread death all over the place.

Personally I'm glad to hear that they are developing the pellet bed
reactor for propulsion applications. BUT, I'm very distressed to hear
that they were looking at using it inside the atmosphere.

--
              Bob Pendleton, speaking only for myself.
   [e-mail] or decwrl!esunix!bpendlet or utah-cs!esunix!bpendlet

                         Tools, not rules.

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

Date: 4 Apr 91 18:33:54 GMT
From: infonode![e-mail]  (Jeff W. Hyche)
Subject: Re: "Face" on Mars

[e-mail] writes:

>  If you want to look for non-terrestrial life, current thought holds that the
>most likely place to find it will be floating high in the atmosphere of
>Jupiter.

    Wonder what is going on in SETI right now?
--
                                  // Jeff Hyche
    There can be only one!    \\ //  Usenet: [e-mail]
                               \X/   Freenet: [e-mail]

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

Date: 3 Apr 91 12:21:43 GMT
From: dev8.mdcbbs.com![e-mail]
Subject: Re: Nova: The Dark Side of the Moon

In article <[e-mail]>, [e-mail] (Fraering Philip) writes:
> I was just wondering if anyone here wanted to discuss
> the recent Nova episodes on the Soviet space program.
>
> I have only seen the second: "The Dark Side of the Moon,"
> and I will see the third one, "The Mission," this Saturday.
>
> Anyone want to start?
>
> If noone does, I have a technical question about the Soyuz.
> From what I saw on the program, the Soyuz doesn't use the
> same attitude control system the Apollo CSMs did (the 4
> thrusters per point, 4 point or whatever it is called).
> What sort of system does it use? Is it efficient? I always
> thought the one on the CSM looked like an optimum configuration,
> but I haven't given it any serious thought.
>
> I suppose a related question would be, where is the location
> of the center of gravity on a Soyuz?
>
> Another good question would be: how hard would it have been to
> have moved their original two-man lunar mission to the Proton
> rocket, using multiple launches? How many Protons would it have
> taken?
>
> Is the Soyuz as good a spacecraft as it was made out to be
> on the program?
>
> Phil Fraering
> [e-mail]
> Disclaimer: whatever a disclaimer is, I guess it applies ;-)

As I recal, the reason for the development of the 4 point system was that it
best served the geometry requirements for the LEM itself, and was adapted
for the CSM in order to reduce duplication of effort. The Soyuz uses a more
complex system similar to the one in the Shuttle ( and in the seperated Command
Module).

  As to how good the Soyuz is? Hard to tell, even with the show. There has
been one major accident with it that killed three Cosmonauts on re-entry, but
like any design that has been kept and refined over the years, has most of the
bugs and problems worked out. By the time the Apollo CSM was retired ( after
Skylab, etc. it had proven itself a good piece of hardware.)

Mike

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

Date: 4 Apr 91 22:14:40 GMT
From: att!cbnewsm!cbnewsl![e-mail]  (Stuart Warmink)
Subject: Re: How 'bout them Titans?

In article <[e-mail]>, [e-mail] (John A. Weeks III) writes:
> Saw it on CNN--it was spectacular!  I liked how the explosion looked
> like an expanding cylinder rather than the typical expanding hemishpere.
> The sparklers caused by flying debris was a nice touch.

But didn't you just love the exclamations on the soundtrack? Almost like
the "ooooohhhh.....ahhhh!" of a good piece of fireworks!
--
------------------------------------------------------------------------------
Stuart Warmink, Whippany, NJ, USA  |  [e-mail]  |       Hi!
------------------------------------------------------------------------------

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

Date: 4 Apr 91 04:40:59 GMT
From: agate!bionet!uwm.edu!linac!pacific.mps.ohio-state.edu!zaphod.mps.ohio-state.edu!unix.cis.pitt.edu!pitt!nss![e-mail]  (Bev Freed)
Subject: ESA's space science dept participates in GRO

European Space Agency
8-10 Rue Mario Nikis
75738 Paris Cedex 15
Telephone: [phone]
Telex: ESA 202 746
FAX: [phone]

FOR RELEASE: MARCH 29, 1991   #8

ESA'S SPACE SCIENCE DEPARTMENT PARTICIPATES IN THE
GAMMA RAY OBSERVATORY

The Astrophysics Division at the European Space Agency's ESTEC (European
Space and Technology Centre) at Noordwijk in the Netherlands built part
of the Imaging Compton Telescope (Comptel), one of the four instruments
carried by NASA's Gamma-Ray Observatory (GRO).

The Observatory, to be launched on 5 April from Cape Canaveral, will be
the heaviest science payload ever deployed by the Space Shuttle in low
Earth orbit -- it weighs over 17 tons and fills half the Shuttle bay.

The Imaging Compton Telescope was built jointly by the Astrophysics
Division at ESTEC, the Max Planck Institute, Garching (Germany), the
Space Research Laboratory at  Leiden (The Netherlands), and the
University of New Hampshire (USA).

Comptel detects gamma rays in the 1-30 MeV energy range, using the
Compton scatter principle (the rays scatter in a detector bank, and
are absorbed by a second detector bank 1.5 meters away).  Comptel's
operational modes and data-handling are controlled by the Digital
Electronics Assembly developed by scientists and engineers of the Space
Science Department (SSD) under the management of Dr. Kevin Bennett.
On-orbit operations of Comptel will be controlled by computers located
in the United States, all the software and hardware for which has been
developed by SSD.  Finally, SSD provided two detectors that will
monitor radio-active sources in order to provide continuous on-board
energy calibration of Comptel.

The Gamma-Ray Observatory is a 3-axis stabilised spacecraft. Its
gamma-ray detectors can be kept pointed in a fixed direction for
observation periods of 14 days each.

GRO's instruments are much larger, more massive, and far more sensitive
than any gamma-ray instruments flown in Space up to now.  Size is
crucial for gamma-ray astronomy: large instruments are needed to
detect a significant number of photons in a reasonable amount of time,
because the number of gamma rays from celestial sources is small.  A
massive detector is required because gamma-rays are highly penetrating
and can be detected only when they interact with matter.

The Goddard Space Flight Center in the US is responsible for the
development of the Gamma Ray Observatory.  The Observatory's operations
will be conducted from Goddard's Payload Operations Control Center
with a remote link to Comptel operations computer in New Hampshire.

Gamma-ray astronomy is the study of celestial objects from their
gamma-ray emissions of photons that have an energy over a million times
that of visible light but whose flux is extremely small.

Gamma-rays are the most energetic of all the forms of electro-magnetic
radiation but Gamma-ray astronomy can only be performed from Space.
Because gamma rays are so penetrating, powerful detectors allow us to
"see" through all the interstellar gas and dust, and out to distant
galaxies.

They help us understand the structure and life-cycle of galaxies, and
give us a unique glimpse of mysterious pulsars and distant quasars.
In 1975 ESA's COS-B satellite used a spark chamber to confirm that
pulsars, and a score of other sources including quasar 3C 273, produce
gamma rays at somewhat higher energies.

"Comptel will make the great break-through in this uncharted lower
energy range just as COS-B did 15 years ago" says Dr. Bennett.

"Detection of gamma rays from Supernovae such as SN 1987-A is a
prime goal, but we are hoping to detect other supernova gamma-ray
emissions as well during the 2- 4-year mission."

For further information, please contact:

Beatrice Lacoste               Heidi Graf
ESA/Paris                      ESTEC Noordwijk (NL)
Tel: [phone]        Tel.: [phone]

Ria Weiland                    Evelyn Leoffler-Stegen
ESOC Darmstadt (FRG)           ESRIN Frascati (I)
TEL: [phone]        Tel.:  [phone]

For further information contact the above address or
ESA Washington Office
L'Enfant Plaza, S.W., Suite 7800
Washington, D.C. 20024
Tel: [phone]
FAX: [phone]


--- Opus-CBCS 1.14
 * Origin: NSS BBS - Ad Astra! [phone] *HST* (1:129/104.0)
--
Bev Freed - via FidoNet node 1:129/104
UUCP: ...!pitt!nss!freed
INTERNET: [e-mail]

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

Date: 3 Apr 91 02:12:32 GMT
From: unisoft!fai!sequent!crg5![e-mail]  (Nick Szabo)
Subject: Re: Chemical rocket complexities

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

>An additional comment: while chemical rockets *are* complex, there is no
>reason to believe that exotic launchers would be significantly less
>complex.  The total operation of a laser launcher, for instance, would
>probably be more complex than anything that has been attempted with chemical
>rockets.

Several things wrong with this:

* The term "exotic".  These technologies are only "exotic" to the
  extent we don't understand them.   It is about time we started
  understanding them.

* Laser launchers use water, not explosive or corossive or
  cryogenic fuel, as reaction mass.  They also have a much
  higher payload/reaction mass ratio, due to laser heating
  being higher efficiency than chemical reactions.  This means
  more payload, less bulk to heft, and thus smaller, simpler
  launch pads.  All in all, quite a bit simpler.

* EML and gas gun vehicles have neither fuel nor reaction mass
  on board (except for the small upper stage), thus are far
  simpler still.

* See more comments below.


>The exotic launchers thus far envisioned would also have very
>high initial costs, and may very well have considerable recurring costs.

An analysis was just posted of EML costs.  Using reasonable, and
sometimes even pessimistic assumptions, up-front costs are less than
a quarter that of chemical rocket projects, and recurring costs are between
100 and 10,000 times smaller, depending on whether we use today's
technology or technology projected for 20 years from today.

The fundamental difference in how energy is stored in the advanced
launch schemes means that the immensity and complexity surrounding
the energy source is focused on the "launch pad", which can be reused
hundreds to millions of times per year, instead of the launcher, which
Shuttle has demonstrated cannot be reused at a reasonable frequency.


>...(Of course there should be funding for continuing research.)

Here we are agreed, but I emphasize that they should be well-funded,
on the level chemical rockets research has been funded during the last
20 years.  Chemical rocket improvments should become the province of
private enterprise, which has produced the major chemical rocket innovations
of the last 10 years, Pegasus and the Aquila engine, despite having less
than 1% of the R&D funds.


>I'm also concerned that there may be some tendency to equate complexity
>with cost.

This is similar to equating any other variable, such as energy, with
costs: it can be a good rule of thumb, but we better have the whole
picture in our minds, to ensure we are not discounting other variables
that could be more important.  This also goes for deciding what "cost"
itself means: entry level costs, cost/lb., cost/response time,
cost/reliability, etc.

--
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 #364
*******************