Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT_ZIP/spacedig/V16_0/V16NO038.ZIP/V16NO038

Internet Message Format | 1993-07-13 | 26KB

Date: Tue, 12 Jan 93 05:05:55
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V16 #038
To: Space Digest Readers
Precedence: bulk


Space Digest                Tue, 12 Jan 93       Volume 16 : Issue 038

Today's Topics:
                       Aluminum as Rocket Fuel?
        Antimatter reality (was Re: *** BUSSARD RAMSCOOP ***)
       Antiproton efficiency (was Re: *** BUSSARD RAMSCOOP ***)
              Chicago presentation on Motorola's Iridium
                    DC-1 and the $23M NASA Toilet
                              DC reentry
                          fiber optic cable
                         future space travel
                                 ISU
                         Latest Pegasus news?
                          Re; Shuttle Toilet
Shameless distortion by APS (was Re: Shameless Hucksterism to Plague STS-54)
  Shuttle a research tool (was: Re: Let's be more specific) (2 msgs)
                      Toutatis Images Available
     Who can launch antisats? (was Re: DoD launcher use) (2 msgs)

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

Date: Mon, 11 Jan 1993 20:09:42 GMT
From: Loren Carpenter <[e-mail]>
Subject: Aluminum as Rocket Fuel?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (John Roberts) writes:
>
>There's a diagram on the wall in the building where I work, depicting the
>formation of metallic powders. A narrow stream of liquid metal is injected
>into a chamber, along with several intersecting high-speed jets of inert gas.
>The physics of interacting jets causes turbulence which tears the stream
>of metal apart. First the liquid metal breaks up into streamers, several
>times as long as they are wide, then the streamers break up into individual
>droplets, which eventually solidify.
>
>The first part of this process could be used to form a fine mist of liquid
>aluminum, presumably using oxygen instead of inert gas. The metal and gas
>are introduced through different openings, which should help to prevent
>buildup of oxide on the injectors.
>
>If you want a more advanced reusable engine, you probably need to bring
>along a supply of inert gas to blow the molten aluminum out of the
>injectors as part of the shutdown process.
>
>John Roberts
>[e-mail]


This reminds me of an observation I made back when I was building small
amateur rockets.  It seems that an easy way to raise the ISP of a fuel is
to preheat it.  An exothermic reaction consumes some of its output in
heating the unreacted material up to reaction temperature.  So, liquid Al
at 1000C ought to burn a bit hotter than solid Al at room temperature.  Also,
to pressurize it, you only need something that is a gas at 1000C, like for
example potassium metal (bp 760C, mp 62C).


    Loren Carpenter
    [e-mail]

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

Date: Mon, 11 Jan 1993 22:18:15 GMT
From: Henry Spencer <[e-mail]>
Subject: Antimatter reality (was Re: *** BUSSARD RAMSCOOP ***)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Bill Higgins-- Beam Jockey) writes:
>> ... There are *NO* fundamental barriers that
>> anyone has been able to find.  It's purely a matter of scaling up and
>> optimizing the hardware -- the existing accelerators are optimized for
>> production of Nobel prizes, not bulk antimatter...
>
>I don't appreciate the gratuitous sneer at the people who sweated to
>get the production rates *this* high.  They solved difficult
>engineering problems and had to make use of technology available at
>HEP labs rather than some blue-sky paper scheme.  And, yes, Simon van
>der Meer did win a Nobel prize for stochastic cooling, an essential
>process in the storage of antiprotons.  So what?

I can't vouch for the exact wording, but the basic comment is from
Robert Forward.  I never saw a good explanation of the details, and
probably wouldn't have retained them if so -- an accelerator expert
I'm not -- but my dim recollection is that the existing systems lose
a good many antiprotons because of wanting a relatively narrow range
of energies, so the antiprotons can be stored and accelerated easily.
They're optimized for their end use -- high-energy particle physics --
not for maximum efficiency in antimatter production.
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

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

Date: 11 Jan 93 19:45:31 -0600
From: Bill Higgins-- Beam Jockey <[e-mail]>
Subject: Antiproton efficiency (was Re: *** BUSSARD RAMSCOOP ***)
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Gregory N. Bond) writes:
>>>>>> On Thursday, 7 Jan 1993 12:03:40 PST, Jon J Thaler <[e-mail]> said:
> Jon> This is about 13 orders of magnitude larger than the total number of
> Jon> antiprotons ever created and stored (about 10**14)
> So, even assuming 100% conversion efficiency, 1kg of antimatter =
> 10^19 Joules, or about 300 years output from a 1GW coal or nuclear
> power station, to produce. It will release twice this amount when
> mixed with ordinary matter.
>
> Now if we could generate antiprotons with better than 50% efficiency,
> we have an inexhaustible energy supply......

As Jon pointed out, you gotta conserve baryon number by all known
processes for creating antimatter (the monopole catalysis Henry
discussed is *highly* speculative and unproven).  So you can't do
better than 50%... and in fact...

> Anyone have estimates on the realistic estimates on achievable
> conversion efficiency?  10^4?

Yes, Bob Forward says the paper limit is 10^-4.  :-(  That's with perfect
collection of *all* antiprotons emerging from the target at all angles
and momenta.  If your p-bar factory is in the real world, your
efficiency will be somewhat lower (Fermilab's is around 10^-9).

Bill Higgins, Beam Jockey         | "I'm gonna keep on writing songs
Fermilab                          | until I write the song
Bitnet:      [e-mail]  | that makes the guys in Detroit
Internet:  [e-mail]  | who draw the cars
SPAN/Hepnet:      43011::HIGGINS  | put tailfins on 'em again."
                                            --John Prine

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

Date: 11 Jan 93 19:55:30 -0600
From: Bill Higgins-- Beam Jockey <[e-mail]>
Subject: Chicago presentation on Motorola's Iridium
Newsgroups: sci.space,chi.general

                 The Chicago Space Frontier Society
         in cooperation with the Mae C. Jemison Space Center
                              presents

                     MOTOROLA'S IRIDIUM PROJECT
                          Gordon Comerford
                        Senior Vice President
        and Group General Manager for Iridium in the Americas
                        Motorola Corporation
                        Schaumburg, Illinois


                               7:00 PM
                      Friday, January 15, 1993
                               Room 106
                        Wilbur Wright College
                          3400  N. Austin Blvd.
                          Chicago, Illinois


Imagine using a small handheld cellular phone to make a phone call
from anywhere on the planet Earth.  The "Iridium" system now under
development at Motorola will provide global cellular telephone
service, as well as other communication services, using a large fleet
of satellites in low Earth orbit.  Mr. Comerford will discuss progress
on Iridium and present a videotape.

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

The Chicago Space Frontier Society, a chapter of the National Space
Society, promotes development of the space frontier and education
about the potential of a spacefaring civilization.  For more
information on CSFS, contact Bill Higgins at [phone] or
[e-mail]. Our thanks to the Mae C. Jemison Space Center
at Wright College for arranging meeting facilities.

Bill Higgins                            Internet: [e-mail]
                                        Bitnet:   [e-mail]

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

Date: Mon, 11 Jan 1993 22:11:07 GMT
From: Henry Spencer <[e-mail]>
Subject: DC-1 and the $23M NASA Toilet
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Ethan Dicks) writes:
>... the Skylab toilet was just a large outhouse in orbit.  The system
>was a very low tech, based on the astronauts filling up plastic bags and
>chucking them into the waste storage area.

Sorry, not correct:  the biomedical investigators wanted those bags,
complete with contents.  They weren't thrown out.

Besides, this misses the point.  *All* of these systems are basically
just aimed at collecting the wastes into a convenient form, which goes
into a holding area pending disposal (on the ground) or medical study.
The significance of the Skylab toilet was that it got solid wastes into
convenient bags quickly and reliably.  That is *not* easy, and it was
the big problem with the earlier stick-on-baggie scheme.

>The toilet on the shuttle was supposed to be a major breakthrough in
>orbital waste management.  The collected human byproducts were supposed
>to be dessicated in the vacuum of LEO and (devoid of significant volume)
>discharged into orbit.

Sorry, not correct.  The old shuttle toilet stores the solid wastes until
landing, when it is removed and cleaned out.  Urine is separated to be
dealt with differently (dumped, I think); this is what has been done by
all such systems, including the Skylab one.

The motive for the new design was that the old one, apart from being
noisy and unreliable, simply had a limited storage capacity.  The new
one basically goes back to the get-it-into-a-bag scheme, with the bags
dealt with (by storing them until landing) separately.
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

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

Date: Mon, 11 Jan 1993 20:36:40 GMT
From: Henry Spencer <[e-mail]>
Subject: DC reentry
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Edward V. Wright) writes:
>... The Delta Clipper *is* shaped
>like a bullet.  It does not present its blunt surface (base) on entry.
>It makes a nose-first, high-angle-of-attack entry modelled after an
>ICBM-warhead trajectory.  This was chosen because of the large amount
>of data available from computer modelling of missile warheads.

Um, it may have shared a certain amount of design heritage with missile
warhead, but I'm pretty sure it does *not* share the trajectory, since
an ICBM-warhead trajectory involves retaining very high velocity down
almost to the ground.  (A certain amount of deceleration is inevitable

in thick low-altitude air.)  A spacecraft, e.g. DC, does almost all of
its decelerating at very high altitudes where the heat load is modest.
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

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

Date: Tue, 12 Jan 1993 01:26:52 GMT
From: Dave Michelson <[e-mail]>
Subject: fiber optic cable
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (John Roberts) writes:
>
>Does anybody (the phone companies or the military, for instance) use
>fiber optic cable that's stiff enough to reduce the risk of breaking?
>
I thought I had just mentioned this in a recent post.  Northern Telecom
encountered the same problem when laying fibre optic cables underground
using a "ditch witch".  Their mechanical engineers came up with a sheath
(I vaguely recall it has a helical structure) which takes up the tension
and protects the cable from breaking.  Anyone from NT on the net?

--
Dave Michelson
[e-mail]

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

Date: Tue, 12 Jan 1993 00:46:53 GMT
From: rabjab <[e-mail]>
Subject: future space travel
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Nick Janow) writes:

>Who needs a gravity well (otherwise known as planet)?  The entire solar
>system could be colonized.  All you really need is raw materials and energy,
>and those exist in convenient packages out in the solar system.
>Do you have to have a planet under you just because your parents did?  Let
>your imagination roam...  :)

While it's fun to let imagination roam, I don't think it necessarily
follows that all dreams translate into reality.

Imagineers (Gerard O'Neill, Robert Forward, and many others), can create
an interesting universe on paper, but I wonder which of their musings
will come to pass.  I don't question their expertise in matters related to
physical law and engineering practice.  However, I do question the stated
economics of the plans of an Imagineer.

The Imagineer is a salesman, and as such, underestimates costs for projects.
And because the dreams of an Imagineer cost billions of dollars to even
start, he has to involve himself and others in the political process, that
grand arena of diminished truthfulness.

-rabjab

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

Date: 12 Jan 93 01:39:19 GMT
From: Dave Michelson <[e-mail]>
Subject: ISU
Newsgroups: sci.space

Where can I find out more about the International Space University?
A site that I could FTP some files from would be great.  What about
application forms? :)

I've heard that the 1993 session will be held at the University of Alabama
at Huntsville but not much else... yet.  Thanks in advance.

--
Dave Michelson
[e-mail]

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

Date: 11 Jan 93 23:46:28 GMT
From: Steinn Sigurdsson <[e-mail]>
Subject: Latest Pegasus news?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Edward V. Wright) writes:

   >one aircraft to the next in the series and in a clean sheet of paper
   >design by a team who has never done any similar work. Name 5 vertical
   >takeoff and landing reusable spacecraft designed by the MacDD team.

   Name five jet airliners designed by Boeing before the model 707.

Well, they weren't airliners, but they did the B-47 and B-52
plus at least one prototype for a tanker - experience directly
related to airliners.

However, I think you focus too much on the -80/707 development
(ignoring that it was a make-or-break for Boeing) - the real
question is whether the Delta Clipper is the 707 of spacecraft
or the Comet :-(

|  Steinn Sigurdsson    |I saw two shooting stars last night        |
|  Lick Observatory    |I wished on them but they were only satellites    |
| [e-mail] |Is it wrong to wish on space hardware?        |
| "standard disclaimer"    |I wish, I wish, I wish you'd care - B.B. 1983    |

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

Date: 11 Jan 1993 22:14 UT
From: Ron Baalke <[e-mail]>
Subject: Re; Shuttle Toilet
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] writes...
>.......On shuttle, you couldn't dump the
>wastes overboard without the possibility of contaminating anything
>in the payload bay, and you didn't have the large empty tank to use.
>(The shuttle dumps waste water overboard, but is very careful about
>when and how it dumps the water from the holding tanks).

Which reminds me, yellow stains were found on LDEF, the long duration
satellite that was in Earth orbit for 5 years.   The stains were analyzed
and determined to be human urine.  It was apparently discharged from the
Space Shuttle (I believe).
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Choose a job you love, and
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | you'll never have to work
|_____|/  |_|/       |_____|/                     | a day in your life.

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

Date: 12 Jan 93 03:42:25 GMT
From: Jon Leech <[e-mail]>
Subject: Shameless distortion by APS (was Re: Shameless Hucksterism to Plague STS-54)
Newsgroups: sci.space

In article <[e-mail]>, "UTADNX::UTDSSA::GREER"@utspan.span.nasa.gov writes:
|> Here is a report on the upcoming Shuttle mission from Francis
|> Slakey of The American Physical Society.  Is it just me, or does
|> anyone else think that NASA's Shuttle people engage in a little
|> too much hucksterism?

    No. I do think that "WHAT'S NEW" has a longstanding vendetta
against NASA (even after Robert Park stopped writing it), and this is
just another case. It's not materially different than the distortions
in Proxmire's Golden Fleece awards. "WHAT'S NEW" makes no pretense of
objectivity and is unworthy of a so-called professional society, IMO.

    The "Toys in Space" stuff may sound silly when presented in APS'
patronizing fashion, but having seen some of the videos NASA has made
in the past from such activities, I think it can produce excellent
educational material in basic mechanics. The dynamics of springs
(slinkys), magnets (marbles), airflow (paper airplanes), etc. in 0-g
are a lot closer to the idealized models in physics books than one
sees on Earth. I'd be surprised if Francis Slakey had ever seen these
videos, though.

|> I especially find the wake-up calls to
|> raucous music annoying - do those people really find that amusing?
|> Do they do their Christmas shopping at Spencer's Gifts?

    Why do you have such a big problem with a humorous tradition?
They're not playing the wakeup calls for your benefit, and it's not as
though there aren't enough real problems with NASA that people have to
invent silly excuses for bashing like this.
--
    Jon Leech ([e-mail])    __@/
    Brice: "How many people don't know anything about it?"
    Andy: "About what?"

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

Date: Tue, 12 Jan 1993 00:20:42 GMT
From: "Edward V. Wright" <[e-mail]>
Subject: Shuttle a research tool (was: Re: Let's be more specific)
Newsgroups: sci.space

In <[e-mail]> [e-mail] (Gary Coffman) writes:

>Ok, let's try it another way. NASA sells Shuttle and it's support facilities
>at cost to Rockwell. NASA then buys a *ticket* when it needs a launch on
>Rockwell Spacelines, about 8 times a year. Rockwell Spacelines sells them
>the tickets at about 1.5 times current Shuttle flight costs, got to recoup
>the investment and turn a profit. The poor taxpayer takes it in the neck.

How about this: NASA seels the Space Shuttle to Rockwell and negotiates
a long-term contract at the same time.  The contract calls for NASA to
purchase 8 flights a year, with penalties for nonperformance, at the same
price NASA pays now.  This would be a no-profit contract if Rockwell
spent as much to launch the Shuttle as NASA does, but Rockwell turns
out to be surprisingly innovative, finds ways to bring costs down,
and makes a tidy profit.

Since NASA has found it can reduce by contracting out many
other operations to private companies (the workforce at KSC
is mainly contractor these days, not NASA), why should the
Shuttle itself be an exception?



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

Date: 12 Jan 93 02:33:27 GMT
From: Steinn Sigurdsson <[e-mail]>
Subject: Shuttle a research tool (was: Re: Let's be more specific)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Gary Coffman) writes:

   In article <[e-mail]> [e-mail] (Henry Spencer) writes:
   >In article <[e-mail]> [e-mail] (Francois Yergeau) writes:
   >>But the airlines do not contract out their operations.  They procure
   >>planes, and fly them, just like NASA buys shuttles and operates them.

   >Actually, it is not at all uncommon for airlines to lease planes complete
   >with crews, or to contract with specialists for support services like
   >maintenance.  Leasing services are among the airliner companies' biggest
   >customers.

   Ok, let's try it another way. NASA sells Shuttle and it's support facilities
   at cost to Rockwell. NASA then buys a *ticket* when it needs a launch on
   Rockwell Spacelines, about 8 times a year. Rockwell Spacelines sells them
   the tickets at about 1.5 times current Shuttle flight costs, got to recoup
   the investment and turn a profit. The poor taxpayer takes it in the neck.

I'm coming in late on this thread, but consider why NASA operates its
own fleet of aircraft rather than lease them for all purposes.
In particular do people contend that say the Kuiper Observatory
should be put on a AA flight rather than a NASA owned Starlifter?

|  Steinn Sigurdsson    |I saw two shooting stars last night        |
|  Lick Observatory    |I wished on them but they were only satellites    |
| [e-mail] |Is it wrong to wish on space hardware?        |
| "standard disclaimer"    |I wish, I wish, I wish you'd care - B.B. 1983    |

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

Date: Mon, 11 Jan 1993 21:21:44 GMT
From: Martin Connors <[e-mail]>
Subject: Toutatis Images Available
Newsgroups: sci.space

In article <[e-mail]> [e-mail]
(Richard Ottolini) writes:
> What is the cell resolution of the radar images in meters and
> what are the factors limiting this resolution?
Please see the Ostro abstract which is the second mentioned in this
excerpt>>>>
Images of minor planet 951 Gaspra returned by the Galileo spacecraft have
shown a heavily cratered surface whose crater density approaches
equilibrium or saturation (the state in which new impacts remove old
craters at the rate new ones are produced) for the smallest resolvable
craters (1)  which are 100m in diameter. .... Apollo-class 4179 Toutatis
.. makes a close approach to Earth on 8 December 1992. ... Radar
investigations (2) should provide similar information about crater density
as is now known for Gaspra.
1. Chapman, C. R. & the Galileo Imaging Team Bull. Am. astr. Soc., 24,
931-932 (1992).
2. Ostro, S. J. Bull. Am. astr. Soc., 24, 934 (1992).
<<<<<<<
So basically Ostro hopes to get 100m craters. I have asked around and been
told that the data inversion is both difficult and iterative, thus will
get better results 'later'. I imagine most of the small stuff being seen
right now is not real....
--
Martin Connors         |
Space Research         | [e-mail]  [phone]
University of Alberta  |

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

Date: Tue, 12 Jan 1993 00:10:49 GMT
From: "Edward V. Wright" <[e-mail]>
Subject: Who can launch antisats? (was Re: DoD launcher use)
Newsgroups: sci.space

In <[e-mail]> [e-mail] (Henry Spencer) writes:

>Define "adequate".  Microsat levels of resolution should be adequate
>for many military requirements.  Tactical commanders don't care about
>the license-plate numbers on the tanks...

If you're planning air strikes with smart weapons, 10-meter resolution
isn't going to cut it.  You need *which* one of those buildings is the
command bunker.

Microsats can supplement our current recon satellites, but can't
replace them.


>Careful here...  I don't know exactly what legal maneuvers took place
>when the US formally joined the UN, but if the UN Charter has the status
>of a Senate-ratified treaty, that means it has the force of law in the
>US... and one of the clauses in there is a renunciation of war as an
>instrument of national policy.

Well, not really.  The "supreme law of the land" is the US Constitution,
not international treaties -- no matter what the State Department might
tell you.  It pretty specifically spells out warmaking powers in terms
that can't be ammended by a simple act of Congress.

All of which is irrelevent because, as I said, George Bush de facto
surrendered US sovereignty in 1992.

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

Date: 12 Jan 93 00:07:49 GMT
From: Steinn Sigurdsson <[e-mail]>
Subject: Who can launch antisats? (was Re: DoD launcher use)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Henry Spencer) writes:

Note changed followup:

E.W.>
   >Of course we didn't.  The United States has gone to war numerous
   >times in the past.  It has never needed permission of the United
   >Nations before.  It was George Bush who set that (dangerous) precendent.

   Careful here...  I don't know exactly what legal maneuvers took place
   when the US formally joined the UN, but if the UN Charter has the status
   of a Senate-ratified treaty, that means it has the force of law in the
   US... and one of the clauses in there is a renunciation of war as an
   instrument of national policy.

   Of course, that just means everybody calls it a "police action" instead...

You mean like Korea? ;-)

*  Steinn Sigurdsson               Lick Observatory          *
*  [e-mail]        "standard disclaimer"      *
*  Just because there's a reason                      *
*  Doesn't mean it's understood              Specials, 1979    *

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

End of Space Digest Volume 16 : Issue 038
------------------------------