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Subject: SPACE Digest V10 #422

SPACE Digest                                     Volume 10 : Issue 422

Today's Topics:
             Defective Software?
         Re: Red Shifts through Random Media
            Re: Nuclear Reactors in Space
         Re: Frequently asked SPACE questions
         NASA Headline News for 01/12/90 (Forwarded)
              NASP Recon. Drones
            Re: Nuclear Reactors in Space
               Airlocks & Life support
----------------------------------------------------------------------

Date: 12 Jan 90 02:35:45 GMT
From: cs.utexas.edu!ut-emx!hutto![e-mail]  (Henry Melton)
Subject: Defective Software?



I am suffering through a software training course, and in the course
materials, there is a table that is used as a 'demonstration' of how
costly minor software errors can be.  The problem is that the
demonstration sounds cooked.  Can someone enlighten me as to the true
stories?

1981    Shuttle launch postponed 2 days
    Cause - miscoded delay factor

70's    U.S. launched satellite toward the Sun rather than Mars
    Cause - missing semi-colon

70's    Simultaneous destruction of several weather satellites
    Cause - missing parenthesis

1962    Mariner I mission to Venus launch rocket off course
    Cause - missing hyphen

Source:    Frank Tatom, _A Model for Estimating the Cost of Typographical
    Errors in Software Development, IEEE Compsac 86_


--
Henry Melton ...!cs.utexas.edu!ut-emx!hutto!henry
1-512-8463241 Rt.1 Box 274E Hutto,TX 78634

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

Date: 12 Jan 90 10:21:35 GMT
From: oliveb!amdahl!rtech!llama![e-mail]  (Glen Kilpatrick)
Subject: Re: Red Shifts through Random Media

In article <[e-mail]> [e-mail] (Anthony E. Siegman) writes:
>The work is by Professor Emil Wolf at the University of Rochester and
>
>however.  In my opinion, the essence of Wolf's work is not that the
>light gets red-shifted, but that when a broad light spectrum passes
>through certain scattering processes a greater fraction of the red end
>of the spectrum (and a lesser fraction of the blue end) gets scattered
>toward the observer, with the result that the light received by the
>observer appears red-shifted compared to the original light spectrum
>before scattering.

I had the impression that, as stars (and by _association_, galaxies)
put out a continua of light overlayed by absorption lines, that a
red shift could only be determined by (and indeed is defined by)
measuring the shift of said lines relative to a laboratory standard.
As the position of the lines would not be shifted re Wolf's theory,
there could be no _red_shift_, only a reddening of the light, and
who is to say what the _original_ spectrum was?  Cooler stars,
older ones (=< ~2*Mass(sun)), etc., are all "red", so what hypothesis
can Wolf test?  His arguments seem interesting, but what's testable?
Adding insult to injury, the analogy with our sun is that said
scattering does happen, and makes wonderful sunsets, but all that
scattered blue light is what makes the sky blue.  So if any
significant cosmological reddening occurs, where is the isotropically
scattered blue?

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

Date: 12 Jan 90 20:17:06 GMT
From: rochester![e-mail]  (Paul Dietz)
Subject: Re: Nuclear Reactors in Space

In article <[e-mail]> [e-mail] (Tim Maroney) writes:

>That research may have not.  However, superconductivity research has
>pointed in that direction.  If the "giant flux creep" problems can be
>solved in the new higher temperature superconductors, then such
>batteries may be feasible.

No, superconducting batteries could not give a sufficiently high
specific energy to replace RTGs.  The reason is fundamental, and
cannot be avoided by design changes.

Any inductor that stores energy experiences net outward JxB forces (a
consequence of a version of the virial theorem).  The battery must be
strong enough to withstand these forces.  The strength of a material
is ultimately a function of the chemical energy liberated when its
atoms bonded together.  The specific energy of a SMES system is
limited by the strength of these chemical bonds.

A good analogy is the mechanical storage of energy in the form
of a compressed gas.  The specific energy here is also limited by
the mechanical strength of materials.

Now, on Earth, a SMES can cheat by letting bedrock carry the stress,
but strictly speaking the specific energy of the system is still
small, since a lot of bedrock is involved.

    Paul F. Dietz
    [e-mail]

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

Date: 12 Jan 90 04:20:17 GMT
From: pacific.mps.ohio-state.edu!zaphod.mps.ohio-state.edu!swrinde!cs.utexas.edu!jarvis.csri.toronto.edu!helios.physics.utoronto.ca!ists!yunexus!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Frequently asked SPACE questions

In article <[e-mail]> [e-mail] (bill davidsen) writes:
>    What's a good reference on
>        the yield of chemical propellants?

A good starting point is George P. Sutton, "Rocket Propulsion Elements",
5th ed (but earlier editions should be fine), Wiley-Interscience 1986,
ISBN 0-471-80027-9.  Best book I've yet found on technical aspects of
rocket propulsion in general (with the reservation that it talks very
little about non-chemical rockets).  Moderately detailed theoretical
treatment of almost everything about rocket engines, with a fair bit
of practical info thrown in.

>        nozzle design?

Sutton does a good first pass on this.

>        simple orbital dynamics (formulas, not theory)

I have trouble figuring out precisely what "formulas, not theory" is
supposed to mean -- you really can't get away from theory for anything
but the simplest aspects, because all too often there are no neat simple
formulas.  That being said, my current favorite is Archie E. Roy's
"Orbital Motion", 3rd ed, Adam Hilger 1988, ISBN 0-85274-229-0.  This
is a reasonably intelligible treatment.  If you absolutely insist on
just a few simple formulas and no theory, though, Max Hunter's old
"Thrust Into Space", Holt Rinehart Winston 1966, no ISBN, is pretty
good.  Unfortunately it's out of print.
--
1972: Saturn V #15 flight-ready|     Henry Spencer at U of Toronto Zoology
1990: birds nesting in engines | uunet!attcan!utzoo!henry [e-mail]

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

Date: 12 Jan 90 18:12:57 GMT
From: trident.arc.nasa.gov![e-mail]  (Peter E. Yee)
Subject: NASA Headline News for 01/12/90 (Forwarded)

-----------------------------------------------------------------
Friday, January 12, 1990                      Audio: 202/755-1788
-----------------------------------------------------------------


This is NASA Headline News for Friday, January 12.....


Astronaut Bonnie Dunbar, operating the space shuttle Columbia's
remote manipulator arm, grappled the Long Duration Exposure
Facility at 10:16 A.M., Eastern time, today, concluding the
nearly 5-year solo flight of the experiment-carrying satellite.
The capture of the LDEF went smoothly.  Following the grapple
the crew of Columbia began an extensive on-orbit photo survey of
the 21-thousand pound space laboratory.

Later today the LDEF wil be stowed away in the orbiter's payload
bay for the trip home.  Between now and next Friday the crew will
busy itself with Earth photography and operating a variety of
microgravity experiments aboard the orbiter.



Aerospace Daily says that funding for ongoing and proposed space
science programs will face tough times when the fiscal 1991
budget proposal goes to Congress in two weeks.  The Daily says
congressional staffers from the House and Senate told them that
there will be a lot of scrutiny of ongoing science projects.  The
majority counsel for the Senate Commerce, Science and
Transportation Subcommittee dealing with space told the Daily he
doesn't think space science is sacrosant as it once was.



The launch of the Global Positioning System satellite aboard a
Delta 2 rocket from Cape Canaveral has been delayed until no
earlier than January 22.  Following a review of test data it was
determined that an accelerometer in the booster's inertial
measurement system must be replaced.



Astronomers meeting near Washington, D.C. have been told of the
existence of one of the largest concentrations of galaxies and
matter ever found.  The New York Times reports the finding could
change the way astronomers think about the structure of the
universe.  Dr. Alan Dressler, leader of the team of astronomers
that discovered the huge structure, says it is so big and covers
so much of the sky that no one looked for it.  Called "the great
attractor"...the object presents enormous problems for theories
of the universe that were standard only 10 years ago.

           *             *           *          *

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


Saturday, January 13....

    4:45 A.M.   Video tape playback of LDEF retrieval ops.

    TBD  A.M.   On-orbit crew news conference

    1:30 P.M.   Videotape replay of day 5 activities.



Sunday, January 14....

    2:20 A.M.   Downlink of fluid experiment apparatus ops

    6:21 A.M.   Crew choice TV downlink

   10:05 A.M.   Downlink of mid deck activities.

    8:30 P.M.   Replay of day 6 activities


Monday, January 15.....

    11:21 A.M.  Downlink of crew choice TV

     4:30 P.M   Replay of day 7 activities



Tuesday, January 16....

    12:35 P.M.  TV downlink of payload bay views

     4:30 P.M.  Replay of day 8 activities.


All events and times subject to change without notice.

-----------------------------------------------------------------
These reports are filed daily, Monday through Friday, at 12 noon,
Eastern time.  There will be no report Monday, January 15, a
federal holiday.
-----------------------------------------------------------------
A service of the Internal Communications Branch (LPC), NASA
Headquarters, Washington, D.C.

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

Date: 12 Jan 90 20:58:44 GMT
From: mintaka!oliveb!orc!mipos3!omepd!omews10.intel.com![e-mail]  (Larry Smith)
Subject: NASP Recon. Drones


The following summarizes an article which appeared in Defense Week;
Jan. 8, 1990; Pg 1.

There is a secret $3 million Air Force study going on to study the
design for a unmanned hypersonic drone that can fly to any continent
in under an hour to perform recon. or strikes. Such a drone would be
designed to fly as fast as Mach 20 (14,000 mph) to outrun the most
advanced air defenses (lasers?). NASP technologies would be used for
such a vehicle. Such a vehicle would be related to current cruise
missiles, but it would be hypersonic, an air breather, do recon.,
and could be recovered.

The study is being done by each of the 3 NASP airframe contractors.
This study is part of a 16 month old DARPA hypersonic research
program. Another study in the same DARPA program is a study of using
hypersonic technology for air interception purposes. The vehicle would
not achieve orbital energy levels (17,000 mph) to avoid violations of
the 1972 ABM treaty banning space weapons.

Some sources say that such a drone could be built for as little
as 150 million, and be rolled out by the end of 1991.

The drone would not have stealth characteristics, it would rely on its
speed to foil intercept attempts (as the A-12 and SR-71 did during their
recon. careers).

Such a drone would be able to do recon. at unpredictable times. One
usage is over threatening 3rd world nations that achieve ICBM capability.

Such a vehicle would probably be the 2nd stage of a 2 stage vehicle. The
first stage could be an aircraft, or a rocket. A vertical launched 1st
stage would look too much like an ICBM launch. The drone's primary
propulsion would be ramjet to scramjet or scramjet only. The drone may
be a glide vehicle over part of its mission. The drone could be designed
so that with configuration changes it could be a strike vehicle.

NASP contractors are worried that such a vehicle would replace the
current NASP concepts. Some former high ranking Air Force officials say
that such a vehicle should not replace the current NASP concepts.

If there is such a project, and it has been going on for 16 months,
the Air Force has much more interest in the NASP program than they
said they did in mid 89. Also they seem to believe in the current
 advantages of air breathing recon.. Namely, fast reaction time,
temporal unpredictability, and spatial capability. So the reason they
are canning the SR-71 is either, it really is too expensive for them
to operate, or they have a replacement (Aurora?).

Larry Smith

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

Date: 12 Jan 90 02:27:34 GMT
From: norge![e-mail]  (John McKernan)
Subject: Re: Nuclear Reactors in Space

In article <[e-mail]> [e-mail] (Neal Woodall) writes:
>3) Because the nuclear reactor actually has a sustained nuclear reaction going
>on inside of it, it needs active control systems to dampen the reaction
>....thus,
>it is much more complex. The RTG, on the other hand, has no sustained reaction
>going on, and needs no active control systems....it is much simpler and safer.

A nuclear reactor does not need active reaction damping controls. In fact
this is a poor design decision and is responsible for many of the problems
nuclear reactors have. Sweden is implementing reactors with active controls
which sustain the reaction. In the absense of such controls the reaction
passively stops. The US is studying such reactor designs.

John L. McKernan.                                                  [e-mail]
Disclaimer: These are my opinions but, shockingly enough, not necessarily Sun's
-------------------------------------------------------------------------------
"There is no such thing as Cyberpunk, but there are alot of imitations."
               - William Gibson

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

Date: 12 Jan 90 20:52:30 GMT
From: agate!shelby!csli![e-mail]  (John Kallen)
Subject: Airlocks & Life support

I've often wondered what happens tro the air in the airlocks when
cosmonauts perform EVAs. Since air is a precious resource in vacuum,
one would imagine that some conservation steps would be taken, yet I don't
see how it would work. Is air sucked out of the airlock prior to the
opening of the outer hatch before EVA exit, or is it dumped in space when
the hatch opens?

In the former case, what kind of mechanism would be required? Is the
evacuation of the airlock the activity that makes EVAs so lengthy timewise?

In the latter case it would seem to be a waste of air. I figure the Progress
modules carry bottles of oxygen. But how often does MIR need to be "refueled"
with air when it is manned? How long can they survive only by recycling with
LiOH(I think?) before they absolutely need more oxygen (disregarding food
and drink availabilty)?

My apologies if these fall into the category "frequently asked questions..."
_______________________________________________________________________________
 | |   |   |    |\ | |   /|\ | John K{llen         "God hates me. *That's*
 | |\ \|/ \|  * |/ | |/|  |  | PoBox 11215          what it is." "Hate Him
 | |\ /|\  |\ * |\ |   |  |  | Stanford CA 94309    back; it works for me."
_|_|___|___|____|_\|___|__|__|[e-mail]___________________________

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

End of SPACE Digest V10 #422
*******************