Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/spacedig/v12_5/v12_579.txt

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Subject: SPACE Digest V12 #579

SPACE Digest                                     Volume 12 : Issue 579

Today's Topics:
       Sea Level RL-10s (was Re:  New Shuttle Engines)
             Re: LLNL Inflatable Station
             Re: The Space Plane
           Hubble Space Telescope Update - 11/16/90
             Re: The Space Plane
              Re: Photon engine
              Magellan Update - 11/19/90
             Re: The Space Plane
              Re: The Ariane V36 failure
         Re: HST Press Conference Wilber Spot
           Re: Pity The Much Abused Shuttle

Administrivia:

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

Date: 19 Nov 90 19:47:37 GMT
From: [e-mail]  (SERRE GLENN)
Subject: Sea Level RL-10s (was Re:  New Shuttle Engines)

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>A badly overexpanded nozzle causes the gas flow to break away from the
>nozzle wall before reaching the end, which causes all manner of nasty
>turbulence and problems of various kinds.  The SSME nozzles are in fact

There is, however, one good effect from separation in an overexpanded nozzle:
If the flow didn't separate (which it usually does at ~0.4 times ambient)
then the exit pressure would be even lowe, resulting in a greater loss of
thrust (compared to the separated case).

>>to adapting the RL-10 to operate at sea level.  Is this a good example of

>In principle, all you need is a shorter nozzle, although you have to think
>about things like the effect on the cooling system.  There may be some
>issues in ignition, too.

Since the RL-10 "bootstraps" on ignition (uses energy from tank pressurization
to spin-up the turbines), you'd have to pressurize the fuel and ox tanks to
about 20 lbs/in2 over atmospheric (for the Centaur G-prime RL-10s).  I can't
imagine that this would be a problem, though.

Trivia and ramblings from


--Glenn Serre
[e-mail]   ([e-mail] will disappear soon. :-( )

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

Date: Mon, 19 Nov 90 18:02:40 EST
From: John Roberts <[e-mail]>
Disclaimer: Opinions expressed are those of the sender
    and do not reflect NIST policy or agreement.
Subject: Re: LLNL Inflatable Station


>From: "Allen W. Sherzer" <[e-mail]>
>Subject: Re: LNLL Inflatable Stations

>In article <[e-mail]>:
>>    I don't know about you, but if I were an astronaut doing an EVA to fix
>>a section of the rotating platform (from damage by space flotsam) and had to
>>get out to the 1 g region, I would first have to spin my body, climb down
>>the rotating station hanging on to it for dear life, with the whole universe
>>and earth rotating at 4 times per second above your head, with an uncomfortable
>>suit on, I certainly wouldn't be in any mood to do any work!

>If I was that astronaut I would be pissed. After all, I went to all that
>work and trouble to get there and when I got there I found somebody had
>already fixed the leak from the inside. It wold ruin my whole day! :-)

>Actually, the ladder idea (and a few other solutions) just came to me
>when thinking about the problem you posed. The part about fixing holes
>from the inside is LLNL's (although I think Freedom plans to do the same
>thing).

How do you fix a pinhole leak in the outer protective layer from the inside?
A giant "hypodermic" filled with glue?

Also, could either layer hold the entire interior pressure if the other layer
should somehow be lost (i.e. rupture at a seam)?
    John Roberts
    [e-mail]

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

Date: 19 Nov 90 19:24:59 GMT
From: mentor.cc.purdue.edu!noose.ecn.purdue.edu!en.ecn.purdue.edu![e-mail]  (/dev/null)
Subject: Re: The Space Plane

In article <[e-mail]>, [e-mail] (John Prentice) writes:
>
> Are you talking about the National Aerospace Plane?  It would fit this
> description, although it is a military project and (to my knowledge) there
> has never been an unclassified explanation of its purpose or mission.  There
> has been lots of press about it, but I think the popular accounts bear little
> resemblence to the real thing (based on my experience working at the Skunk
> Works on it several years ago).
>
> John Prentice

I thought it was also funded by NASA for use as an eventual replacement for
the shuttle or an alternative to it...

    I believe it was the X-29 or X-30 NASP ????

Brent

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

Date: 19 Nov 90 02:49:58 GMT
From: usc!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Hubble Space Telescope Update - 11/16/90


                             HST Status Report
                             November 16, 1990

     NASA's Hubble Space Telescope (HST) activity progressed officially this
week from orbital to science verification, according to Joseph H. Rothenberg,
Associate Director of Flight Projects for HST at Goddard Space Flight Center.
The milestone means the operational activity of the telescope now will
devote more time to calibration of the five scientific instruments onboard the
spacecraft and less on engineering calibration of the spacecraft.

     "We still have some orbital verification residuals," explained Dr.
Keith Kalinowski, head of the HST Science Management Office at Goddard, "and we
will continue to eliminate these."  Among those residuals, he said, is further
diagnosis of the telescope's pointing and stability problem and an improved
calibration of instrument aperture locations relative to the Fine Guidance
Sensors.

     The HST, launched last April, has suffered a number of problems, primarily
a manufacturing flaw in the primary mirror that prevents proper focussing and a
"jitter" caused by the solar arrays when the spacecraft transitions from
daylight to darkness.  NASA plans to launch a repair mission to correct the
major problems with the telescope in 1993.

     Before the problems were discovered, officials had anticipated orbital
verification could be completed in three months.  Describing the continuing
program, Kalinowski explained, "we will start the science verification period
with a high proportion of instrument calibrations.  By June, 1991, we hope to
be devoting one-half the time to science and one-half to commissioning
activities.  As the year progresses, the science proportion will increase
and, by October, we expect to be doing 80 percent science."

     HST officials hope to complete science verification by December, 1991.
The science verification activity is managed by the Goddard Space Flight
Center.  Upon completion of that activity, the science operations
management will be turned over to the Space Telescope Science Institute at
Johns Hopkins University in Baltimore, which operates under a NASA contract
supervised by Goddard.
      ___    _____     ___
     /_ /|  /____/ \  /_ /|
     | | | |  __ \ /| | | |      Ron Baalke         | [e-mail]
  ___| | | | |__) |/  | | |___   Jet Propulsion Lab | [e-mail]
 /___| | | |  ___/    | |/__ /|  M/S 301-355        |
 |_____|/  |_|/       |_____|/   Pasadena, CA 91109 |

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

Date: 18 Nov 90 22:59:41 GMT
From: unmvax!ariel.unm.edu!ghostwheel.unm.edu![e-mail]  (John Prentice)
Subject: Re: The Space Plane

In article <[e-mail]> [e-mail] writes:
>
>    I was curious if anyone out there knew anything about a possible space
>plane. Some magazines mentioned a experimental high altitude "space plane" that
>could be used to ferry cargo into low earth orbit and could be used commercialy
>to fly passengers from say...New York to Sydney in five hours. I believe it was
>called the "X-87" or something like that. Does anyone know what I'm talking
>about??

Are you talking about the National Aerospace Plane?  It would fit this
description, although it is a military project and (to my knowledge) there
has never been an unclassified explanation of its purpose or mission.  There
has been lots of press about it, but I think the popular accounts bear little
resemblence to the real thing (based on my experience working at the Skunk
Works on it several years ago).

John Prentice

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

Date: Mon, 19 Nov 90 12:37:14 EST
From: John Roberts <[e-mail]>
Disclaimer: Opinions expressed are those of the sender
    and do not reflect NIST policy or agreement.
Subject: Re: Photon engine


>From: usc!cs.utexas.edu!news-server.csri.toronto.edu!helios.physics.utoronto.ca!physics.utoronto.ca![e-mail]  (Christopher Neufeld)
>Subject: Re: Photon Engine

>   Well, this is a bit outside of my field, but my understanding of laser
>technology is that a %10 efficiency isn't bad for a high power laser. This
>would imply a power consumption of 110GW. Clearly this isn't what's going
>on. Try dissipating 99GW of heat in a laser tube......also, 110GW compares
>well with the power output of entire nations.

>If you could manage 11GW
>continuously, that would be interesting. That's almost 40N of thrust (in
>real units). Put you heat radiators on the back of the spacecraft and you
>might double that from the waste heat being preferentially radiated against
>the direction of thrust. Even a 100 ton spacecraft could use that much
>thrust for a relatively quick transit to Mars.

> Christopher Neufeld....Just a graduate student  |
> [e-mail]    Ad astra! |  S = k log W

Or you could bring along a few tons of reaction mass, and get there much
faster with much less power. Pure photon drives are OK when you absolutely
can not get reaction mass, like maybe intergalactic travel, or when the
energy source is somewhere else, like the sun. I believe it's always more
energy efficient to apply energy to any amount of reaction mass than it is
to drive off photons alone.

I believe we established some months ago that radiation pressure from a big
flat plate produces half as much thrust as a directed beam of photons.
Applying this to the example you give above, with a 10% efficient laser,
the thrust from the radiators would total 4.5 times the thrust from the
laser! Of course, the laser would be more effective for fighting kzinti :-) ,
or accidentally frying your friends and neighbors, blowing out telescopes, etc.
:-( .

This highlights an interesting point. Unless you can build a *very* efficient
laser, there's very little advantage to a photon drive in using a laser as
opposed to just putting a reactor in back and letting it glow, while a laser
would add considerable cost and reduce reliability.
    John Roberts
    [e-mail]

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

Date: 19 Nov 90 20:43:57 GMT
From: usc!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Magellan Update - 11/19/90


                       MAGELLAN STATUS REPORT
                         November 19, 1990

     The Magellan spacecraft is performing nominally in mapping mode, and has
just completed its 369th mapping orbit.  Image data from 361.2 orbits has been
successfully transmitted to Earth.  All DESATS (desaturations) over the weekend
were nominal, and 21 out of 22 STARCALS (star calibrations) were successful
with small attitude updates.

     Since November 16, the limit value on attitude updates was reset to .07
degree, and the heartbeat loss table was reset to its configuration prior to
the recent loss of signal incident.

     The radar system is performing nominally.  Later today, an evaluation of
the playback performance, using the new data management strategy which avoids
tracks A2 and A4, will be completed.

     The SAR (Synthetic Aperture Radar) Data Processing Team reprocessed the
SAR data from orbits 419, 447, and 547 to achieve improved quality.  The
normal flow of new image swaths is not scheduled to resume until November 26.
      ___    _____     ___
     /_ /|  /____/ \  /_ /|
     | | | |  __ \ /| | | |      Ron Baalke         | [e-mail]
  ___| | | | |__) |/  | | |___   Jet Propulsion Lab | [e-mail]
 /___| | | |  ___/    | |/__ /|  M/S 301-355        |
 |_____|/  |_|/       |_____|/   Pasadena, CA 91109 |

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

Date: 19 Nov 90 18:51:19 GMT
From: unmvax!ariel.unm.edu!ghostwheel.unm.edu![e-mail]  (John Prentice)
Subject: Re: The Space Plane

>I'm fairly certain NASP is a commercial venture. What I'm not sure of
>is, is NASP the same as the X-29? Maybe the X-29 is the military vehicle
>you're talking about.
>
>Anyway, from what I've heard, NASP is coming along pretty well. I think
>it was just posted recently that the contractors of NASP all got
>together to decide on a final fuselage shape. They also said materials
>development (extremely heat resistant, etc.) was also going well.
>
>I'd love to hear more about the the progress of NASP myself.
>

I haven't been involved with NASP for about three years now, so maybe
alot has changed.  At that time however (before the down select to the
current contractors), the project was ridiculously oversold.  We do not
understand (or didn't then and I really doubt we do now) the issues of
supersonic combustion or how to build the materials required for this
enterprise without active cooling.  We don't even have a way to test
this thing since there are no wind tunnels that get anything close
to mach 20!  The project was sold by DARPA partly on the theory that
fluid dynamics calculations would provide the answer, but that is
not going to happen (speaking as a fluid dynamicist and code developer).
We don't even have a realistic idea of what the viscosities should be
in these calculations, much less the calculational capability to do
realistic 3d simulations of complex geometries.  Perhaps all these issues
are no longer important (as I said, I have not followed this in years) and
if so, I would be very interested to hear from someone who knows.  Also,
is NASP still intended to achieve orbit without rocket assist or have
they conceded defeat on that one?

Is there another project besides NASP (i.e., X-29 or X-30 or whatever) ?
Who is funding it?  Also, I would be interested to find a printed
reference to an official explanation of the purpose of NASP.  When I
was involved with it, even the designers were unable to articulate it.
There was lots of speculation, but anything official was classified.  It
was (is?) afterall a "gray" program.  If I sound antagonistic about
NASP, I apologize, it just seemed extremely ill-conceived 3 years ago
and what I kept reading in the newspapers had no resemblence to what
I saw being designed.  If this has changed, please enlighten me.

John Prentice
Dept of Physics and Astronomy
University of New Mexico

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

Date: 18 Nov 90 14:51:22 GMT
From: crash!orbit!pnet51![e-mail]  (S Schaper)
Subject: Re: The Ariane V36 failure

Somebody tore their shirt on the end of the pipe and the scrap got left in
when reassembled?

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

Date: 18 Nov 90 14:51:36 GMT
From: crash!orbit!pnet51![e-mail]  (S Schaper)
Subject: Re: HST Press Conference Wilber Spot

W-i-i-i-i-i-ilbur???
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------------------------------

Date: 18 Nov 90 22:07:04 GMT
From: mips!wdl1.wdl.fac.com!wdl76![e-mail]  (Jon W Meyer)
Subject: Re: Pity The Much Abused Shuttle

[e-mail] (J. Taggart Gorman) writes:

>In article <[e-mail]> [e-mail] (Doug Mohney) writes:
>>In article <[e-mail]>, [e-mail] writes
>>
>>Wrong Bbbbbuck. Shooting out the windshield on a jeep results in lots of glass
>>and maybe you might kill someone. If you're Rambo, you dive out of the jeep,
>>tastefully tuck-and-roll, then return fire. If the windshield of the shuttle
>>gets shot out, and you don't happen to be wearing a space suit, you suck
>>vaccuum. Should you be so fortunate enough to get into a space suit,
>>Ivan-the-Terrible has now boarded the shuttle to finish the job he started.

>  Since this shuttle would knowingly be going into combat, all personel
>*would* be in 'suits, because depressurization would be the first thing mean
>'ole Ivan would try.

Certainly.  Now, explain how the shuttle is going to get home with that
nasty whole in its windshield.  The only advantage to attempting such a
re-entry is that the crew may die faster - less suffering.

>  It looks like we're writing the script for Rambo VII,

It certainly does.

>the one where the
>bad Russian space Colonel captures Rambo's one-and-only-friend-and-best-buddy
>and take him to his sekret nuklear space battle fortress.  Since NASA doesn't
>want to waste a shuttle to save Rambo's one-and-only-friend-and-best-buddy,
>good 'ole Rambo sneaks into the evil USSR and steals a Russian shuttle (damn!
>forgot the name!  "My mind is going......" - Hal & me) and on the way to the
                    ^^^^^^^^^^^^^^^^ So, that explains this thread. :-)

BTW, the Soviet Shuttle is Bruan (SP?).

>sekret nuklear space battle fortress, Rambo destroys all of the evil Russian
>space forces, and several TIE fighters.

>  Sounds like a winning script to  me!  :)

Listen.  You keep writing movie scripts.  I'm sure folks would love them.
Just leave the actual application of space tech to the folks who know
something about it.  Otherwise, someone may take you seriously and call
for the men in white coats who will bring you your very own special
jacket.

Jon

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

End of SPACE Digest V12 #579
*******************