Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT_ZIP/spacedig/V15_4/V15NO452.ZIP/V15NO452

Internet Message Format | 1993-07-13 | 28KB

Date: Tue, 24 Nov 92 05:07:28
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #452
To: Space Digest Readers
Precedence: bulk


Space Digest                Tue, 24 Nov 92       Volume 15 : Issue 452

Today's Topics:
                              Databases
            FREE-ENERGY TECHNOLOGY For Spacecraft (2 msgs)
                        GE Aerospace (2 msgs)
                                 HST
                                 ISU
                         Moon Capture Theory
                       Pumpless Liquid Rocket?
                    Putting telescopes on the moon
                      Shuttle Computer Problems
                          Shuttle computers
                            Solar sailing
           STS-53 Mission Emblem (crew patch) Now Available

    Welcome to the Space Digest!!  Please send your messages to
    "[e-mail]", and (un)subscription requests of the form
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    (THENET), or [e-mail] (Internet).
----------------------------------------------------------------------

Date: 24 Nov 92 01:47:49 GMT
From: Craig Fifer <[e-mail]>
Subject: Databases
Newsgroups: sci.space

I realize that this may not help you (because I don't know if
you can access the following databases through e-mail), but
other users may find this of use:

Lunar and Planetary Institute
lpi.jsc.nasa.gov (146.154.14.11)
Username: lpi

NASA Spacelink
spacelink.msfc.nasa.gov (128.158.13.250)

NASA NSSDC Online Data and Info Service
nssdca.gsfc.nasa.gov (128.183.10.4
SET HOST NSSDC or NSSDCA
Username: NSSDC or NODIS

NASA/IPAC Extragalactic Database
ipac.caltech.edu (131.215.139.35)
login: ned

Space Physics Analysis Network Information Center
nssdca.gsfc.nasa.gov (128.183.36.23)
Username: SPAN_NIC


I would imagine that these are accessible by telnet, but I have
not used all of them.  I hope this helps someone!

-Craig Fifer
[e-mail]
--
_____________________________________________________________________________
|   Never play leapfrog with              |   Craig Fifer                   |
|   a unicorn!   -Murphy                  |   3736 Heritage Road, S.W.      |
|                                         |   Roanoke, Virginia  24015-4518 |

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

Date: 23 Nov 92 23:08:09 GMT
From: Steve Taylor <[e-mail]>
Subject: FREE-ENERGY TECHNOLOGY For Spacecraft
Newsgroups: sci.space

[e-mail] writes:

>     The technology described in the article copied below could be used to
>power spacecraft, space colonies, etc.:
>
>
>                            FREE-ENERGY TECHNOLOGY
>                       by Robert E. McElwaine, Physicist

Didn't you post this gibberish a month or so ago? How about some new stuff?

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

Date: 24 Nov 92 05:43:36 GMT
From: Patrick Chester <[e-mail]>
Subject: FREE-ENERGY TECHNOLOGY For Spacecraft
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Brad Whitehurst) writes:
]In article <[e-mail]> [e-mail] writes:
]
]>     The technology described in the article copied below could be used to
]>power spacecraft, space colonies, etc.:
]>
]>
]>                            FREE-ENERGY TECHNOLOGY
]>                       by Robert E. McElwaine, Physicist
]...
]    I think we just found the REAL "Mr. Ozone"!  Is there anyone
]at U. of W. Eau Claire who can verify if this is a real person?  Does
]he do anything but post these articles?
]--

I've emailed queries about his er, theories and have gotten back a few
paragraphs of tripe in reply. Can you program a computer to send replies
via email? Whatever. I guess I could try emailing him again but I don't
know if that will work. I flamed him to hell last time and never got a
reply back. Oh well

--
Patrick Chester            |----------------------------------------------------
[e-mail] |"The earth is too fragile a basket in which to keep
Politically Incorrect      |  all your eggs." Robert A. Heinlein
Future Lunar Colonist      |"The meek can *have* the Earth. The rest of us are
#^%$!! Militarist          |  going to the stars." Robert A. Heinlein
(Of the Sun Tzu mentality) |----------------------------------------------------

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

From: Mark Benson <[e-mail]>
Subject: GE Aerospace
Newsgroups: sci.space

Nntp-Posting-Host: colorado
Reply-To: Mark Benson 5-4228 <[e-mail]>
Organization: GE Medical Systems, Milwaukee,  WI
Date: Mon, 23 Nov 92 21:59:42 GMT
Lines: 106
Source-Info:  Sender is really [e-mail]
Source-Info:  Sender is really [e-mail]

Responding to an earlier query - the following lifted from internal GE mail
and redistributed (gasp) without permission.  Having heard this on NPR, I
believe it to be no problem...

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

MARTIN MARIETTA TO AQUIRE GE AEROSPACE FOR $3.05 BILLION IN CASH, SECURITIES

WASHINGTON (NOV. 23) UPI - The Martin Marietta Corp. and General Electric Co.
jointly announced Monday they have reached a definitive agreement to merge GE's
Aerospace businesses into Martin Marietta in a deal valued at $3.05 billion.

Under terms of the transaction, GE will receive cash and $1 billion in
convertible preferred stock in Martin Marietta.

Martin Marietta will support GE's nomination of two additional members to its
expanded board of directors.

The merger will combine two of the nation's leading aerospace research and
development organizations and will expand the new Martin Marietta's competitive
position in such diversified markets as space, communications, defense,
electronics, information, technical services, materials and energy.

The GE Aerospace businesses that will join Martin Marietta are major suppliers
of satellites, radar and sonar systems, simulation systems, communications
systems, government technical services and other aerospace and defense systems.

Revenues from these operations in 1991 exceeded $6 billion.

The merger also provides for Martin Marietta's use of General Electric's
Corporate Research and Development Center as part of a continuing cooperative
agreement between the two firms.

With the addition of the GE operations, Martin Marietta's annual revenues will
nearly double, approaching $11 billion, including approximately $3 billion in
sales from commercial and civil government customers.

Martin Marietta's backlog will increase to $19 billion, not including $9
billion in Department of Energy operating contracts.

The merger has been approved by both Martin Marietta's and General Electric's
Boards of Directors but is subject to government review and the approval of
Martin Marietta shareowners.

The transaction is expected to close during the first half of 1993.

Included in the transaction are GE Aerospace, headquartered in Valley Forge,
Pa., and with major locations in Syracuse, Binghamton and Utica, N.Y.;
Moorestown, Cherry Hill, East Windsor and Camden, N.J.; Pittsfield, Mass.;
Burlington, Vt.; and Daytona Beach, Fla.

Also included in the transaction are GE Government Services, headquartered in
Cherry Hill, N.J.; Knolls Atomic Power Laboratory in Niskayuna, N.Y.; and the
Machinery Apparatus Operation in Schenectady, N.Y.

Martin Marietta's employment will be about 94,000 people, including 27,000
engineers and scientists.

Norman R. Augustine, chairman and chief executive officer of Martin Marietta,
and John F. Welch, Jr., chairman and chief executive officer of General
Electric, said the merger was ''a significant milestone in the creation of
stronger, healthier, more competitive companies as the aerospace industries
undergo necessary consolidation.

''We expect substantial benefits for our customers, shareowners and employees
as a result of this agreement,'' Augustine and Welch said.

''The GE and Martin Marietta businesses are very complementary. Through the
more efficient use of facilities and resources and with the application of a
broader range of advanced technologies, Martin Marietta will enhance its
effectiveness in meeting the nation's substantial ongoing national security and
commercial aerospace requirements,'' Augustine and Welch said.

''The new company will be a lower cost, more competitive and more innovative
global supplier,'' they added.

Augustine said ''This agreement brings together two outstanding organizations
to create an even stronger one and will have both immediate and long-term
value.

''We often have been partners with GE Aerospace and we have a great deal of
admiration for its excellent employees as well as for the quality of their
technology and products.

''This new Martin Marietta meets our three strategic objectives for continued
prosperity, strengthening of our core businesses, expansion into
closely-related civil and commercial markets, and enhancement of shareowner
value,'' Augustine added.

Welch said ''This merger is consistent with a belief central to GE management
strategy over the past decade, that businesses must be number-one or number-two
in their marketplace to succeed in the highly competitive global arena, or have
a way of getting there.

''This merger will allow the new company to walk into the global arena as
number-one in its industry, with twice the resources and a fraction of the
overhead of the two companies that created it.

''We at GE have a long-term commitment to this new company. The agreement
presents a unique opportunity for GE Aerospace employees to be part of a
dynamic enterprise that is well-positioned for the challenging
businessenvironment ahead,'' Welsch added.

--
Mark Benson                    [e-mail]
GE Medical Systems (until they sell us:^)    Milwaukee, WI   USA

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

Date: Tue, 24 Nov 92 01:36:45 EST
From: John Roberts <[e-mail]>
Subject: GE Aerospace

-From: [e-mail] (Mark Benson)
-Subject: Re: GE Aerospace
-Date: 23 Nov 92 21:59:42 GMT
-Organization: GE Medical Systems, Milwaukee,  WI

-MARTIN MARIETTA TO AQUIRE GE AEROSPACE FOR $3.05 BILLION IN CASH, SECURITIES

-WASHINGTON (NOV. 23) UPI - The Martin Marietta Corp. and General Electric Co.
-jointly announced Monday they have reached a definitive agreement to merge GE's
-Aerospace businesses into Martin Marietta in a deal valued at $3.05 billion.

Don't forget the important custom in contempory business - any big corporate
merger or significantly improved product must be given a silly synthetic
name - this is a goodwill gesture to one's competitors, to eliminate the
unfair advantage of name recognition. Since "Unisys" and "Pentium" have
already been taken, how about "SnorkelDyne"? If that's not silly enough,
maybe "MaGMEl", though that has the disadvantage of being noticeably
derived from the constituent names.

-Martin Marietta will support GE's nomination of two additional members to its
-expanded board of directors.

And we all wondered where David Letterman would end up!

(Just kidding. :-)

John Roberts
[e-mail]

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

Date: Tue, 24 Nov 92 01:50:59 EST
From: John Roberts <[e-mail]>
Subject: HST

-From: [e-mail] (John F. Woods)
-Subject: Re: Shuttle replacement
-Date: 23 Nov 92 15:09:00 GMT

-And, of course, since Hubble wasn't designed to withstand the rigors of
-being brought back (though that was the original intention), doing so could
-result in *needing* to build a new one -- after having spent a billion dollars
-:-).

It could *probably* withstand return to Earth and relaunch, but given a
plausible chance at repair in orbit, landing it is not the preferred
method. (Analogy - if you had a medical problem that could be fixed by
open-chest surgery or (much more cheaply and safely) by taking pills for
a few weeks, wouldn't you be more attracted by the option of the pills?)
If the primary or secondary mirror were shattered by an impact, they
probably would plan to return it to Earth. (Those parts are not designed
for in-orbit replacement.)

-[The ride down is not all that smooth, and Hubble is a big, delicate
-piece of optics.]

I wouldn't say the optics were the main concern for landing damage, except
for the risk of contamination. The main problem is probably all those
thousands of mechanical parts and electrical connections. Judging by the
massive redundancy built into the system, I suspect they didn't expect HST
to do nearly as well as it did during launch - they were lucky, and aren't
anxious to press their luck.

John Roberts
[e-mail]

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

Date: 23 Nov 1992 12:35 PST
From: "Horowitz, Irwin Kenneth" <[e-mail]>
Subject: ISU
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Scott A Koester) writes...
>   I am highly interested in obtaining information about the International
>Space University, anyone know who I can contact and where? Valid email
>addresses would work also.  Give me responses in email please, i would greatly
>appreciate it. Thanks everyone....
>
Folks,
    Just to follow up on the message I sent out last week.  The person to
contact at ISU is Mr. Steve Abrams and his e-mail address should be:
        [e-mail]
I had the incorrect e-mail address in my post last week.
-------------------------------------------------------------------------------
Irwin Horowitz                        |
Astronomy Department                  |"Whoever heard of a female astronomer?"
California Institute of Technology    |--Charlene Sinclair, "Dinosaurs"
[e-mail]                |
[e-mail]                 |
-------------------------------------------------------------------------------

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

Date: 23 Nov 92 15:36:40 GMT
From: Curtis Roelle <roelle@uars_mag.jhuapl.edu>
Subject: Moon Capture Theory
Newsgroups: sci.space

[e-mail] (James Davis Nicoll) writes:

>>>I seem to remember some theory a while back that the moon was actually
>>>*captured* by Earth at some stage (I think it was about 800 million
>>>years ago), which also has corollaries in some of the very early
>>>human legends.

>    I  find  it *very* difficult  to believe  that events  800
>million  years ago would  have corollaries  in  the myths of  a species
>4  orders of magnitude less old, except  perhaps by co-incidence.

Perhaps these corollaries originated from an intelligent species of lizard
wiped out without a single trace by the Mother of all Extinction Events.

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

Date: Mon, 23 Nov 1992 23:52:41 GMT
From: Mark Schlegel <[e-mail]>
Subject: Pumpless Liquid Rocket?
Newsgroups: sci.space

[e-mail] (Henry Spencer) writes:

>>That is connect the tankage to the rocket engine
>>with a long pipe.  When accelerating (or at
>>rest in a gravity field) hydrostatic pressure
>>at bottom of pipe can be fairly high...

>The hydrostatic head in the plumbing, while useful -- it figures into the
>design calculations for both pump-fed and pressure-fed rockets -- is not
>enough to run a pressure-fed engine particularly well.  Even low-performance
>pressure-fed engines need 5-10 atmospheres of pressure.  (One atmosphere is
>a 10m column of water, and most fuels and oxidizers are substantially less
>dense than water.)

>I'd also expect stability problems, given the increase in feed pressure as
>thrust increases.

Not really, you could put a valve at the bottom of the pipe that would
vary the flow rate due to feedback from flow sensors in the pipe and
accelerometers in the rocket.

Mark

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

Date: 23 Nov 92 20:52:56 GMT
From: Roger Arnold <[e-mail]>
Subject: Putting telescopes on the moon
Newsgroups: sci.space

[e-mail] (John Roberts) writes:
>
>[..]
>Would speckle interferometry, or integration of the incoming signals over
>very long periods of time (hours to weeks) help with reception? (Other than
>the fact that planets move over such time intervals.)
>
>I think you've made your point that the resolution formula can't be extended
>out to infinity. I'd be interested in how far it *can* be extended with, say,
>100 high-precision 10-meter optical telescopes.
>
>John Roberts
>[e-mail]

To be pedantic about it, speckle interferometry isn't applicable to
space-based telescopes; it's a specific technique for partially
overcoming distortions and blurring caused by the unstable atmosphere
that ground based telescopes have to look through.

Signal integration over long periods of time does help.  The trouble
is that the improvement in signal to noise ratio is only proportional
to the square root of the observing time.  To get 10x in single-to-
noise over some reference observation, you need 100x the observing
time.

But if each element in the LBI array can individually resolve the
signal you're interested in, then you can derive spatial structure
to a level commensurate with the size of the virtual aperture that the
array synthesizes.  Given 100 high-precision 10-meter optical scopes
on the moon as the array elements, then mapping the continents on
planets of nearby stars should be quite do-able.

In my earlier reply, I may have come across as more negative on the
idea than I really am.  Actually, I'm a staunch advocate of space
telescopes, precisely because they offer the potential for direct
observation of extra-solar planets.  Consider the impact of even one
fuzzy point of bluish light, whose spectrum revealed an atmosphere
with significant water vapor and free oxygen; it would revolutionize
our thinking every bit as much as the Apollo images of earth from the
moon.

The point I was making is that before you can start playing LBI games
with extra-solar planetary images, you need individual telescopes that
are extremely impressive in their own right.  They have to be capable
of resolving the traces of light from the planet from the overwhelming
glare of light from its primary.  Calculations that I once did showed
that, for the dozen nearest stars, a 10-meter aperture would do the
job--if the optics were nearly perfect.  For a reflector, the mirror
would need to be manufactured to the same level of tolerance as the
Hubble mirror.  It would have to be of one piece, not segmented, and
it would have to focus off-axis.  Light diffracted from mirror segment
boundaries, or from an on-axis secondary mirror and support struts,
would overwhelm the feeble light from the planet.

A telescope mirror of that size and quality, 4 times the diameter and
16 times the area of the Hubble mirror, could theoretically be built.
It would, however, be a daunting task.  Telescopes incorporating such
mirrors would be far too large to be built on earth and shipped to a
lunar base for setup and operation by a handful of astronauts.  So--to
get back to the original thread from which this subject split--I don't
think one gets to count extra-solar planetary observatories in the
justification for a lunar base.

--
Roger Arnold
[e-mail]

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

Date: 24 Nov 92 03:59:56 GMT
From: [e-mail]
Subject: Shuttle Computer Problems
Newsgroups: sci.space

Monday November 23 10:20 EST

I'm looking for some help out here in the net. Any physists or experts
in electron physics out there?
   The problem we're having is with both the General Purpose Computers
(GPCs) onboard the shuttle as well as the Main Engine Controllers (SSMEC).
Both experience single bit upsets while in orbit. The GPCs have one bit
error correction and log these upsets in what we call a soft error counter.
For the SSMEC, it has no error correction. We dump the SSMEC memory after
landing and determine how many upsets have occurred. Well today when the
SSMECs were powered up on Discoveries three Main Engines, the standby
computer on engine 3 had one bit flipped from the last time it was powered
up (about a week ago). The GPCs have also experienced soft errors while at
the pad. The current theory is that high energy particles striking the
memory cell impart energy which changes the state. My question is if
high energy particles can change the memory on the shuttle sitting on the
pad. Why aren't all the other computers in the world inflicted with the
same problem? Has anyone heard any studies being done on this?

Some info, the SSMEC uses 8K static RAM chips to make up the 64K by 16 bit
main memory. When power is removed the memory is held up by a 3.56V
battery. Todate it is believed that all bit flips have occurred at this
lower battery voltage (power up voltage is 5V). This of course can not
be proved (could have happened at full power in memory that was not being
accessed).

Thanks.

---------------------------------------------------------------------------
Bob Waterman [Aqua]
[e-mail]
---------------------------------------------------------------------------

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

Date: Mon, 23 Nov 92 22:25:10 GMT
From: Dave Jones <[e-mail]>
Subject: Shuttle computers
Newsgroups: sci.space

Henry Spencer ([e-mail]) wrote:
> In article <[e-mail]> [e-mail] (Craig Keithley) writes:
> >> It's not a cycle-by-cycle lockstep like some redundant systems.  Every
> >> couple of milliseconds, the four computers in the main redundant set
> >> compare notes...
> >
> >I seem to recall that this is correct; that the four computers running the
> >same code are on something like a 40ms main event loop...
>
> When I said "every couple of milliseconds", I meant it. :-)  It's actually
> about 440 cycles per second, which may be what you're remembering.  This

If its *exactly* 440 Hz then it gives a whole new meaning to "keeping things
in tune".......


--
||------------------------------------------------------------------------
||Dave Jones ([e-mail])|Eastman Kodak Co. Rochester, NY  |

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

Date: Tue, 24 Nov 92 01:14:01 EST
From: John Roberts <[e-mail]>
Subject: Solar sailing

-From: [e-mail] (Christopher Neufeld)
-Subject: Re: Solar sailing
-Date: 23 Nov 92 16:48:24 GMT
-Organization: University of Toronto Physics/Astronomy/CITA

-In article <[e-mail]> [e-mail] (John Roberts) writes:
->Most proposed solar sails are reflective, not black. That's because the
->principles of conservation of momentum show that reflecting the beam of
->light can greatly increase the thrust of the sail. The best results
->are with a 100% reflective sail perpendicular to the beam of light (theta = 0)
->that doubles the thrust.

-   Well, yes, for certain definitions of 'best results'. Unless your
-sail+payload has a very low mean mass per unit area, though, the net
-force on the sail is still going to be sunward.

That was sloppy wording on my part - I meant the angle where the total
thrust of the sail is greatest. I would not presume to specify the optimum
setting for various orbital maneuvers - that's where the math gets *hard*. :-)

-Since the solar pressure
-falls off as the square of distance just the way gravity does, the effect
-of setting the sail at normal incidence to the sun is the same (from a
-mathematical point of view) as instantaneously reducing the mass of the
-sun while maintaining the position and velocity of the spacecraft fixed
-over that instant.

Which means that the required mass per unit area of a non-orbiting solar
sail that can support itself against the sun's gravity is pretty much
independent of distance from the sun - an interesting phenomenon.

-   The usual trick is to set the sail at an angle to the spacecraft-sun
-line. Since the radial component of the thrust does no net work over one
-complete orbit (to first order, it helps a bit to second order if the
-sail is not at normal incidence), the sail should be set at an angle to
-maximize the tangential thrust. This angle is about 35 degrees for a
-perfectly reflecting, planar sail.

Argh! Jon Leech pointed out an error in my calculations for a black sail,
and now your figure of 35 degrees causes me to realize that it applies
equally to a flat reflective sail - the incident beam makes no contribution
to the tangential thrust - that's wholly dependent on the tangential
component of the reflection (if any). So the math from the relevant
parts of my earlier post should be changed to:

Terms: P = power per unit area of incident beam (watts / meter^2)
       c = speed of light (~3E8 m/s)
       theta = angle that sail is off from perpendicular to beam
       Fr = radial (direction of beam) force vector on sail
       Ft = tangential (sideways) force vector on sail
         (Fr, Ft measured in Newtons per square meter of sail)

Black sail:
Fr = P/c * cos(theta)
Ft = 0

Reflective sail:
Fr = P/c * cos(theta) * (1 + cos(2 * theta))
Ft = P/c * cos(theta) * sin(2 * theta)

Using these formulas, the optimum angle for tangential thrust works out
to about 35.26 degrees (tangential thrust = ~.77 of the force of the incident
beam), which fits pretty well with your number.

(See folks? That's why it pays to have your math checked by other people! :-)

(Jon agreed with my conjecture on uniformly diffuse light sources and
diffuse reflectors.)

Bonus question (meaning I don't have any idea how to work out the math):
  In designing sails for sailboats, it usually works out that the optimum
  sail is a nonplanar piece of fabric, mounted with some slack so that the
  wind inflates it to a particular curved shape. Is that also the case
  for a solar sail, when one wants to maximize tangential thrust per unit of
  sail area? (If so, the mechanism would be multiple reflections.)

John Roberts
[e-mail]

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

Date: Tue, 24 Nov 1992 00:30:48 GMT
From: [e-mail]
Subject: STS-53 Mission Emblem (crew patch) Now Available
Newsgroups: sci.space.shuttle,sci.space

The mission emblem for STS-53 is now available for anonymous FTP at
  ames.arc.nasa.gov:/pub/SPACE/LOGOS/sts-53.*

This batch of files includes all of the usual formats and the text
from the back of the decal.  Check out:
  ames.arc.nasa.gov:/pub/SPACE/LOGOS/README
for the list of available space logo files, graphics formats, etc.

(Hey, I got this one out BEFORE the mission this time.)

-- Ken Jenks, NASA/JSC/GM2, Space Shuttle Program Office
      [e-mail]  [phone]

     "The STS-53 insignia shows the Space Shuttle Discovery rising to
      new achievments as it trails the symbol of the Astronaut Office
      against a backdrop of the American flag.  The five stars and
      three stripes also symbolize the mission number -- STS-53 -- and
      America's continuing commitment to world leadership in space.
      The pentagonal shape of the patch represents the Department of
      Defense and its support of the Space Shuttle Program.  The band
      delineating the flag from space includes the four colors of the
      military services of the crew members."
        -- The STS-53 Crew Patch Description

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

End of Space Digest Volume 15 : Issue 452
------------------------------