Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V11_1/V11_110.TXT

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Subject: SPACE Digest V11 #110

SPACE Digest                                     Volume 11 : Issue 110

Today's Topics:
         NASA Headline News for 03/02/90 (Forwarded)
            Re: Magellan Update - 03/02/90
          Re: Spacecraft drives and fuel efficiency
         Space Station (was: Realtime Unix?)
             NORAD to AMSAT Quick Track ?
           Re: Shuttle Payload Bay Question
           Re: Shuttle Payload Bay Question
               Re: Lunar Comm.
               Payload Reports
          Re: Spacecraft drives and fuel efficiency
               Re: Aviation Week Videos
                  SPACE JOBS
----------------------------------------------------------------------

Date: 2 Mar 90 18:32:37 GMT
From: trident.arc.nasa.gov![e-mail]  (Peter E. Yee)
Subject: NASA Headline News for 03/02/90 (Forwarded)

-----------------------------------------------------------------
Friday, March 2, 1990                         Audio: 202/755-1788
-----------------------------------------------------------------
This is NASA Headline News for Friday, March 2......

The White House has named NASA as the lead agency in the mission
to the moon and Mars initiative.  The program will define at
least two significantly different approaches to the goal.  The
program will perform mission, concept and systems analysis
studies along with technology development.  The DoD and the
Department of Energy will also have major roles in technology
development concept definition.  To facilitate coordination, the
Department of Energy will be added as a formal member of the
National Space Council.

The orbiter Discovery, scheduled for the STS-31 mission will be
transferred from the Orbiter Procesesing Facility to the Vehicle
Assembly Building at Kennedy Space Center on Monday.  There it
will be mated to the solid rocket boosters and external tank.
Roll out to launch pad 39-B is set for March 16 with a launch
target date of April 12.  Discovery's mission will be to deploy
the Hubble Space Telescope.

The STS-35 Columbia systems testing at the Cape is underway.
Operations include servicing the orbiter with potable water, a
crew hatch functional test, leak and functional testing as well
as checks of the main propulsion systems.  The ASTRO payload is
scheduled to be installed in the payload bay the middle of this
month.

The Galileo spacecraft is 48.4 million miles from Earth today.
Although the trajectory leads eventually toward Earth for the
next gravity-assist boost in December, the distance will continue
to increase for the next three months.  Galileo has now gone 226
million of the 2.4 billion Miles along the looping 6-year path to
Jupiter.  The next flight sequence to be sent to Galileo is being
reviewed.

The Park Seed Company announced that some of the 12.5 million
tomato seeds exposed to the rigors of six years of space travel
on LDEF appear to be germinating normally.  A summary report this
fall will reveal the response to radiation that may indicate a
difference in the growth process and color -- revealing a loss in
chlorophyll -- which will determine whether food can be grown in
outer space.

A Titan booster will launch the first of two Intelsat VI
communications satellites from Cape Canaveral on March 14.  The
Martin Marietta commercial booster will also launch a second
Hughes Space and Communications Group satellite in June.



                                 ###




-----------------------------------------------------------------
Here's the broadcast schedule for public affairs events on NASA
Select TV.  All times are Eastern.


Sunday, March 4...

     Time to be announced         Landing of STS-36 shuttle
                                  Atlantis at Edwards Air Force
                                  Base in California.


All events and times are subject to change without notice.
-----------------------------------------------------------------
These reports are filed daily, Monday through Friday, at 12
noon, Eastern time.
-----------------------------------------------------------------
A service of the Internal Communications Branch (LPC), NASA
Headquarters, Washington, D.C.

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

Date: 3 Mar 90 15:23:28 GMT
From: bfmny0![e-mail]  (Tom Neff)
Subject: Re: Magellan Update - 03/02/90

In article <[e-mail]> [e-mail] (Ron Baalke) writes:
>     Flight software will be changed to add a background filter to the star
>scan process which will allow for all crossing data in an interrupt window
>to be buffered. The filter will then select the two best crossings, based on
>magnitude of each star. This change will reduce the number of failed star
>scans.

I'm curious about something in general.  One of the geniuses of the space
program, I won't say just the US's although that's what we mostly hear
about, is our ability to improvise and tinker with launched probes,
especially in software, to overcome unexpected obstacles.  Voyager is
rich with examples, and now we read about similar heroics with Magellan
and Hipparcos and Galileo.

The question is, are the lessons learned and the tricks we come up with
DOCUMENTED and passed on to future spacecraft designers?  Or do they
languish in a few geniuses' brains until they retire, or get buried in
the guts of some endless moldering rack of mission paperwork or stacked
magtapes in a department office somewhere?

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

Date: 2 Mar 90 21:21:07 GMT
From: cs.utexas.edu!jarvis.csri.toronto.edu!helios.physics.utoronto.ca!ists!yunexus!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Spacecraft drives and fuel efficiency

In article <[e-mail]> [e-mail] (Christopher Neufeld) writes:
>...The first antimatter drive will probably inject the energy from an
>annihilation reaction into a vessel of water. The water would be boiled,
>and atomised, and the superheated oxygen and hydrogen plasma would stream
>out a nozzle at the back. Perhaps liquid hydrogen would be more efficient,
>but water is safer, at least in atmosphere, and more convenient to handle...

Water is not a good choice for such things.  At high temperatures it becomes
a strong oxidizer, which causes really ugly materials problems.  If one
did not want to use hydrogen, methane or ammonia would probably be a
better choice.  (Methane is cryogenic; ammonia isn't *very* cryogenic.)
However, for almost any sort of thermal rocket you want to use hydrogen
if you possibly can, because the low molecular weight gives the highest
exhaust velocity.
--
MSDOS, abbrev:  Maybe SomeDay |     Henry Spencer at U of Toronto Zoology
an Operating System.          | uunet!attcan!utzoo!henry [e-mail]

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

Date: 3 Mar 90 02:55:06 GMT
From: telesoft![e-mail]  (Bob Kitzberger @sation)
Subject: Space Station (was: Realtime Unix?)

In article <[e-mail]>, [e-mail] (Gerry Kokodyniak) writes:
>
> It also appears that NASA will be using a realtime UNIX system (i.e. LYNX OS
> - a Sys V R 3.2 derivative with BSD features) for use on the space station
> (for whenever it comes into being).

I've heard (sources secret ;-) that LYNX OS won't be used _everywhere_, i.e.
there will still be embedded applications that will use non-UNIX executives.
Anybody know more on this?

Supposedly, NASA is planning on using Rate Monotonic Scheduling rather than the
more traditional Cyclic Executive on the Space Station.

    .Bob.

--
Bob Kitzberger                  Internet : [e-mail]
TeleSoft                        uucp  :    ...!ucsd.ucsd.edu!telesoft!rlk
5959 Cornerstone Ct. West       at&t  :    [phone] x163
San Diego, CA 92121-9891        "Dawn : The time when men of reason go to bed."
------------------------------------------------------------------------------

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

Date: 2 Mar 90 05:46:31 GMT
From: epiwrl!boom![e-mail]  (Mike Peyton)
Subject: NORAD to AMSAT Quick Track ?


 Does anyone have a way to convert the NASA/NORAD Prediction Bulletins directly
to the N4HY's AMSAT Quick Track KEPC.DAT file? It get's old putting all those
numbers by hand.......

-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+
     Mike Peyton             USENET: ...!uunet!epiwrl!boom!mike
     4209 Tulare Dr.       INTERNET:   [e-mail]
     Wheaton, MD 20906      MCIMail:   M Peyton or 324-8388
            w 703-749-7381     h 301-933-2273
-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+

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

Date: 3 Mar 90 11:30:28 GMT
From: swrinde!cs.utexas.edu!jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Shuttle Payload Bay Question

In article <[e-mail]> [e-mail] (Frank P. DiGiuseppe) writes:
>All this talk about LDEF, and whether it was protected from the atmosphere,
>has me wondering: when and how is pressurization/depressurization of the
>payload bay performed? Is the bay air-tight? Is contained air simply
>released when the doors are opened in orbit (I kind of doubt this...)?
>Is re-pressurization performed after landing?

The payload bay is not pressurized and is not air-tight, so contained
air leaks out during ascent and (fairly warm!) air leaks back in during
descent.  Some of the reference material I've got hints at vents being
provided, although it's not absolutely clear on this.
--
MSDOS, abbrev:  Maybe SomeDay |     Henry Spencer at U of Toronto Zoology
an Operating System.          | uunet!attcan!utzoo!henry [e-mail]

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

Date: 3 Mar 90 20:50:41 GMT
From: unmvax!nmtsun![e-mail]  (Timothy Younts)
Subject: Re: Shuttle Payload Bay Question

Frank (and the gang!), I thought I would attempt my first posting
to add to the discussion about Orbiter venting.

Henry's response to your question is correct.  As I recall there are
something like 10 to 20 vents located throughout the orbiter, including
not only the payload bay, but also the forward RCS (Reaction Control
System) pod and the aft OMS (Orbital Manuvuering System) pods.
These vents are computer controlled w.r.t. the particular flight phase
being accomplished (w/ manual override, as well).  These vents become a
very important part of the checklist procedures if a consumables leak
(propellant, water, etc.) is detected (allows liquid to sublimate out of
the orbiter and into space).

I wish I could remember more, but it's been 2 yrs since I was involved
with NASA/STS, and the vents were not in my immediate realm of expertise
( for 3 yrs I was a propulsion/guidance/flight control instructor in the
Shuttle Mission Simulator at JSC ).  I hope this helps...!

Best Regards,
Tim Younts    ( [e-mail] )
New Mexico Institute of Mining and Technology
Socorro, NM

P.S.-
 I hope continuing this discussion outside of sci.space.shuttle is ok?!

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

Date: 4 Mar 90 00:27:57 GMT
From: wuarchive!cs.utexas.edu!jarvis.csri.toronto.edu!helios.physics.utoronto.ca!ists!yunexus!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Lunar Comm.

In article <[e-mail]> [e-mail] writes:
>Is there an accepted way for calculating how far away the horizon is for an
>observer at a given height?  ...

The triangle running from observer to horizon to the planet's center is
a right-angle triangle (the right angle is at the horizon).  So we have:

distance = sqrt( (radius+height)^2 - radius^2 )
    = sqrt( radius^2 + 2*radius*height + height^2 - radius^2 )
    = sqrt( 2*radius*height + height^2 )
    ~= sqrt( 2*radius*height )       if radius >> height

This is slant distance, actually, not surface distance, but unless the
tower is really high or the planet is very small, it's close enough for a
first approximation.

Of course, on a real planet, you get to worry about all sorts of nasty
complications like mountains.
--
MSDOS, abbrev:  Maybe SomeDay |     Henry Spencer at U of Toronto Zoology
an Operating System.          | uunet!attcan!utzoo!henry [e-mail]

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

Date: 2 Mar 90 23:58:04 GMT
From: usc!elroy.jpl.nasa.gov!zardoz.cpd.com!dhw68k!ofa123![e-mail]  (Mark Perew)
Subject: Payload Reports

Peter -

I spoke with a person at the Marshall Space Flight Center who is
associated with the SpaceLink BBS.  I asked why the Payload Status
Reports were not available on SpaceLink.  The reply was that
Public Affairs management at Marshall felt that the reports issued
from KSC were not sufficiently accurate and that the publisher o
of these reports should check the reports with the KSC technical
people.

Are you (or anyone else in receipt of this message) aware of any
specific problems with the payload reports published by KSC?  It
seems extremely bizarre to me that the Shuttle Status Reports are
issued by KSC and appear on SpaceLink, but the same organization
produces the payload reports and those are deemed to be not worthy
of publication.

Thanks for your input.



--
Mark Perew
...!{dhw68k,lawnet,conexch}!ofa123!Mark.Perew                             [e-mail]
714 544-0934 2400/1200/300     [PCP: CASAN]

[disclaimer.std]

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

Date: 2 Mar 90 19:37:06 GMT
From: sco![e-mail]  (Nathaniel Ingersoll)
Subject: Re: Spacecraft drives and fuel efficiency

In article <[e-mail]> [e-mail] (Tim Maroney) writes:
:In article <[e-mail]> [e-mail] (David Schneider)
:>You may not have noticed :-), but all existing space propulsion systems
:>fry the immediate vicinity when they take off...
:
:Hmm.  How much antimatter would you have to annihilate to escape the
:gravity well?  Micrograms per launch?  I tend to think it would "fry"
:the immediate vicinity a little worse than extreme heat does.  Wouldn't
:there be a good deal of residual radiation, especially after multiple
:launches of large craft?  Current launch pads are reusable pretty
:quickly, and the atmospheric pollution is insignificant.

In most of the anti-matter proposals I have seen, you don't just
chuck some antimatter behind you to react, blow up and push you
forwards; you have it react somewhat internally to superheat
some sort of reaction mass (likely candidate is H2O), and throw
that mass out behind you at a high velocity.  I suppose that you
could have the reaction take place in a reasonably shielded
containment area (on second thought, how easily do gamma rays
go through water?).
--
________________________________________________________________________________
  I told the police that I was not injured,
  but on removing my hat, I found that I
  had a skull fracture.                     -- from an insurance accident form

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

Date:        Sat, 03 Mar 90 09:02:41 AST
From: [e-mail]
Subject:     Re: Aviation Week Videos

On  Date: Wed, 28 Feb 90 15:16 EST
Mark C. Widzinski <[e-mail]> writes:
>
> I came across a flyer from AW&ST advertising a series of video
> tapes.  Some of the title sound interesting:  "SR-71 Blackbird:
>
> Has anyone seen these videos?  They're all $50 which is a little
> much to blow on a low quality flick.  Any critiques or comments
> would be welcome.

I have "SDI, The Technical Challenge" and "Space Shuttle: The Recovery."
They are both professionally done, very interesting, and to me worth
the $50.

========================================================================
Richard B. Langley                  BITnet:  [e-mail] or [e-mail]
Geodetic Research Laboratory        Phone:   [phone]
Dept. of Surveying Engineering      Telex:   014-46202
University of New Brunswick         FAX:     [phone]
Fredericton, N.B., Canada  E3B 5A3
========================================================================

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

Date: 3 Mar 90 14:06:46 GMT
From: phoenix![e-mail]  (Marc Wayne Mcconley)
Subject: SPACE JOBS

PRINCETON PLANETARY SOCIETY is pleased to announce a new publication.

"SPACE JOBS:  The Guide to Careers in Space-Related Fields," is a
26-page booklet listing companies which have jobs available in
space-related fields, whether you're looking for a summer job or a
full-time career.  "SPACE JOBS" also lists schools which offer graduate
programs in space.  The publication even gives helpful hints on how to
go about landing your perfect space job!

"SPACE JOBS" is available from the Princeton Planetary Society for
$2.00 per copy.  Order your copy today!

To order, please send check or money order for $2.00 per copy, payable
to "Princeton Planetary Society" to:

Editor, SPACE JOBS
Princeton Planetary Society
315 West College
Princeton University
Princeton, NJ 08544

--
Marc W. McConley
Vice President, Princeton Planetary Society
Reply-To:  [e-mail]  ||  [phone]

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

End of SPACE Digest V11 #110
*******************