Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/spacedig/v16_9/v16no896.txt

Text File | 1993-07-20 | 35KB | 891 lines

Space Digest                Tue, 20 Jul 93       Volume 16 : Issue 896

Today's Topics:
                          3-man Shuttle EVAs
                       7/19/93 KSC News Release
                       7/19/93 NHQ News Release
                        aerobraking manoeuvre
                            Atlas A/C 104
                              Clementine
                         Gaubatz talk on DC-X
                  GPS in space (was Re: DC-1 & BDB)
                   Hubble, Why the hurry? (3 msgs)
                          Isp of solid fuels
                       LRDPA & Return to the Mo
                           Mars Direct Info
                              Nitpicking
                Very basic questions about dark matter

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

Date: 20 Jul 1993 00:04:30 GMT
From: Dave Akin <[e-mail]>
Subject: 3-man Shuttle EVAs
Newsgroups: sci.space,sci.space.shuttle

In article <[e-mail]> jeff findley, [e-mail]
writes:
>> Provisions are
>> being made for 3-man EVAs, although there are no specific plans for
any.
>
>What provisions are necessary for 3-man EVAs (besides carrying an extra
suit)?
>How exactly do they get those three guys into and out of that small
airlock?
>I know this has been done before, but I had problems getting the details
of
>*how* this is done.
The basic problem is that there are only two servicing mounts for
the EMUs in the airlock. In a typical EVA, the crew closes out the
suits, checks the systems, goes through a prebreathe to get residual
nitrogen out of the bloodstream, and depressurizes the airlock, all
while using consumables from the orbiter via the suit umbilicals.
They only go on internal consumables right before egressing, so
they maximize their EVA time (around 8 hours without any
reserves, typical EVAs rum between 6 and 7 maxed out.) One
problem is that EV3 has to get dressed outside the airlock, due to a
shortage of volume in the airlock (one of the IVA crew is in there
too, helping EV1 and EV2 go through the checklists), and then
enter the lock and breathe off internal consumables while the other
two finish the pre-egress checklists on the umbilicals. Bottom line
is that EV3 has about 1.5 hours less time outside than the other
two. At the end of his nominal consumables, s/he comes in, hangs
himself (or herself, of course) on the wall, and breathes off of the
umbilical while the other two finish. There are also some
complications on contingency procedures, and more work on suit
recycling, but the biggest problem is sharing two umbilicals among
three people, and the fact you're not getting the full time out of
EV3.

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

Date: 19 Jul 93 14:42:00 +0600
From: Bill Loewy <[e-mail]>
Subject: 7/19/93 KSC News Release
Newsgroups: sci.space

                        MISSION: STS-51  ACTS-TOS/ORFEUS-SPAS


          VEHICLE: Discovery/OV-103             ORBITAL ALTITUDE: 184 miles
          LOCATION: Pad 39-B                    INCLINATION: 28.45 degrees
          LAUNCH DATE: TBD                      CREW SIZE: 5
          LAUNCH WINDOW: TBD
          EXPECTED KSC LANDING DATE/TIME: TBD
          EXPECTED MISSION DURATION: 8 days/22 hours + 1 day (an additional
          day on orbit may be granted if orbiter cryogenics and allow)

          IN WORK TODAY:
          *  Troubleshooting of the ground pyrotechnic initiator controller
          *  Argon servicing of the ORFEUS payload
          *  Trickle charge on ACTS batteries

          WORK SCHEDULED:
          *  Ordnance installation and reconnect operations
          *  Load onboard cryogenic reactants
          *  Aft engine compartment closeouts and aft confidence test
          *  Final payload bay closeouts and close payload bay doors for
             flight

          WORK COMPLETED:
          *  Open payload bay doors
          *  Off load of onboard cryogenic tanks
          *  Ordnance disconnect and safing operations
          *  Remove mid-deck payloads for reservicing


          NOTE:  Launch of the space shuttle Discovery on mission STS-51
          was scrubbed Saturday at the T-20 minute mark due to a problem
          with a switch in the pyrotechnic initiator controller (PIC) which
          governs the pyrotechnic circuits on the Shuttle. The problem was
          narrowed down to a prematurely charged capacitor in the firing
          circuit of all eight Solid Rocket Booster hold down posts and the
          T-0 liquid hydrogen vent arm, located on the side of the external
          tank. This charge is normally initiated at the T-18 second mark.

               Work to repair the circuit, located on the mobile launcher
          platform, is now underway.

               A specific launch date has yet to be determined. NASA
          managers are discussing launch day options.



               The five members of astronaut crew departed for their homes
          in Houston on Saturday. Their schedule to return to KSC will be
          determined by the setting of a new launch date.

               The crew for this mission include: Commander Frank
          Culbertson, Pilot Bill Readdy, and Mission Specialists Jim
          Newman, Dan Bursch and Carl Walz.


        **END**

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

Date: 19 Jul 93 14:47:15 +0600
From: Bill Loewy <[e-mail]>
Subject: 7/19/93 NHQ News Release
Newsgroups: sci.space

DAILY NEWS/TV SKED 7-19-93

Daily                News
Monday, July 19, 1993  Two Independence Square; Washington, D.C.



 % STS-51 launch delayed;
 % HST observations;
 % JSC Director to retire.

Officials decided to scrub Space Shuttle's Discovery's STS-51 mission
Saturday, July 17, at about 8:52 a.m. EDT because all eight of the
solid rocket booster hold down bolts and the T-0 liquid hydrogen
vent arm, located on the side of the external tank, were prematurely
charged with current.  This charge is normally
initiated at the T-18 second mark in the countdown.

Schedules have been made to drain the orbiter's fuel cell storage
tanks and to disconnect or safe pyrotechnic initiator controllers in
various areas of the vehicle and payload.  Officials estimate this
work will be completed today, allowing time to troubleshoot the
pyrotechnic racks inside the mobile launcher platform.

At this time, a new launch date has not been decided.

* * * * * * * * * * * * * * * *

Recent NASA Hubble Space Telescope (HST) observations indicate
that a class of active galaxies further support the theory that they
are fueled by a massive black hole at the center.  This observation
rules out vigorous star formation as the alternative explanation for
the mysterious power source behind quasars and extremely bright
galactic nuclei.

Alexei V. Filippenko, Professor of Astronomy, University of
California at Berkeley,
states that "Our observations provide perhaps the most direct
evidence to date
that normal Seyfert galaxies and quasars are not powered by a burst
of star
formation."  Filippenko further explained that the most likely
alternative is the
standard model in which the energy is provided by matter falling
into a black hole.

The Seyfert galaxies are nearby galaxies with extremely bright
central regions
that often obscure the much dimmer stars in the surrounding
galaxy. Quasars are
among the most distant objects in the universe and can be seen
from earth
because they are so bright.  Seyfert and Quasars, collectively
referred to as active
galactic nuclei (AGN), give off a enormous amount of energy.

A black hole is a theoretical object that is so compact its intense
gravity prevents
even light from escaping.  In the standard model for AGNs , dust,
gas and stars
falling into the black hole heat up as they collide and release
tremendous amounts
of radiation.

Previous HST observation have found additional circumstantial
evidence for the
presence of massive black holes in the core of active galaxies:  dust
disks, "light-
cones" of ionizing radiation and extremely dense stellar
concentrations consistent
with theoretical models for the presence of a black hole.

* * * * * * * * * * * * * * * *

Johnson Space Center Director Aaron Cohen recently announced his
retirement effective August 20.  Cohen has accepted appointment as
the Zachry Professor of Engineering at Texas A&M University.  Paul
J. Weitz, Deputy Director of the Johnson Space Center, will act as
Director upon Cohen's departure.

Cohen has more than 33 years of distinguished service with the
government, 31 of those years with NASA.  NASA Administrator
Goldin said "Aaron represents all of the finest you can hope for in a
government servant.  His career and his accomplishments speak for
themselves.  He provides a benchmark.  He has
brought technical excellence, integrity, dedication and leadership to
the Johnson Space Center and NASA.  His career serves as an
example to us all, and he leaves behind a lasting legacy."

Goldin announced that Cohen will serve as Special Consultant to the
Administrator on human flight as well as research technology along
with his responsibilities at Texas A&M.

 * * * * * * * * * * * * * * * *



Here's the broadcast schedule for Public Affairs events on NASA TV.
Note that all events and times
may change without notice and that all times listed are Eastern.

Monday, July 19, 1993

        noon            NASA Today.
        12:15 pm        The Night Sky with Dr. Rich Terrile.
        12:30 pm        America's Wings.
          1:00 pm       Apollo 10 Sorting Out Unknowns.
          1:30 pm       Magenetic Effects In Space.
          2:00 pm       Starfinder #3.
          2:30 pm       Our Laboratories in Space.
          3:00 pm       TQM #3.

Tuesday, July 20, 1993

        noon            NASA Today.
        12:15 pm        Aeronautics & Space Report.
        12:30 pm        Apollo 11 Anniversary/KISS: Apollo.
          1:00 pm       Apollo 11: For All Mankind.
          1:30 pm       Return to the Red Planet.
          2:00 pm       Starfinder #4.
          2:30 pm       Life on the Moon.
          3:00 pm       TQM #4.



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

Date: 20 Jul 93 03:13:50 GMT
From: Samuel Mallinson <[e-mail]>
Subject: aerobraking manoeuvre
Newsgroups: sci.space

Some time ago, there were some posts re: an aerobraking manoeuvre that was
going to be attempted with a vehicle that was (then) orbiting Venus.  My
supervisors have performed some experiments involving aerobrake geometries
and when I mentioned this to them, they said they would be interested to hear
of the outcome of the Venus attempt.  If anyone has a report, or a summary, or
even a ftp server addres from which I may obtain the above, I would be most
grateful if they could send it/them to me at:

[e-mail]

or by post to:

Sam Mallinson
Dept Aerospace & Mechanical Engineering
University College, UNSW, ADFA
Canberra ACT 2601, Australia

Thanks in advance.

Sam Mallinson

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

Date: Tue, 20 Jul 93 01:49:39 GMT
From: Dean Adams <[e-mail]>
Subject: Atlas A/C 104
Newsgroups: sci.space

Atlas Centaur 104, with a DSCS III bird onboard lifted off
from the Cape today at 6:04 pm ET... it was a PERFECT launch!

Its about time GD's luck turned around!

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

Date: 16 Jul 93 04:00:04 GMT
From: [e-mail]
Subject: Clementine
Newsgroups: sci.space

HS>In article <[e-mail]>
HS>[e-mail] writes:
HS>>Clementine will orbit the moon next year, as part of a BMDO sensor
HS>test, but is not *really* a lunar scientific mission...

HS>Actually, it's not a bad lunar scientific mission, within its limits.
HS> The major limit is that its sensors are not optimized for lunar
HS>science except in small ways (like choice of filters).  In particular,
HS?it's a purely optical mission, with no gamma/neutron instruments.
HS>--


I am told that it's optics are inferior to the normal NASA optics in
several ways:

sensitivity to radiation is high (meaning radiation in the space
environment will tend to degrade the images)

and the resolution is comparable to a Lunar Orbiter (as in the Lunar
Orbiter from the 1960's).

I am told that this is due to its unique mission (to test BMDO military
sensors) - the optics are extremely small and light, but not to the normal
NASA specs.

I would love to be corrected on this - Clementine is a wonderful mission,
but I don't want to get our hopes too high that this will be the Lunar
Orbiter that we have all waited 21 years for.

___ WinQwk 2.0b#0

--- Maximus 2.01wb

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

Date: 20 Jul 1993 01:06:27 GMT
From: "P. Douglas Reeder" <[e-mail]>
Subject: Gaubatz talk on DC-X
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Ward Paul) writes:
:In article <21om23$[e-mail]> [e-mail] (P. Douglas Reeder) writes:
:>     The software was written by a package called Matrix-X.
:>Designers feed in equations and the package outputs Ada
:>code, which is compiled without being further modified by
:>humans, eliminating most of the need for testing, according
:>to Dr. Gaubatz, and allowing a new version of flight
:>software to be created in two days.
:
:Yipes!  Please, please test your software.

Since the input is some collection of equations, and the code produced
is always for the same application, it seems likely that some theorums
of provably-correct software have been applied.  I suspect this is
akin to changing the value of a constant in source code and
re-compiling.  For some program constants, within certain bounds (and
assuming a program designed to allow this) one can do this with
confidence that the result is as bug free as the last compile.
However, I do not know the details.


--
Doug Reeder                              Internet: [e-mail]
Div, Grad & Curl                         USENET:   ...!tektronix!reed!reeder
programming & derivative work
I am actively seeking scientific programming contracts.

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

Date: 19 Jul 1993 21:39:48 -0400
From: Pat <[e-mail]>
Subject: GPS in space (was Re: DC-1 & BDB)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (fred j mccall 575-3539) writes:
|In <229kmb$[e-mail]> [e-mail] (Pat) writes:
|
|
|>Reasons for a High Inclination Orbit :
|
|>1)  Cheap Soviet flights available.
|
|That's not a valid reason unless you've already decided to chuck the
|U.S. capability in this area in the interests of short-term monetary
|savings.
|

It is possible to Take advantage of cheap soviet flights,
without sacrificing US capabilities.

If we swap to a high inclination orbit,  it means  we can
swap some of the construction flights to the soviets,  while
flying other shuttle dependent missions, like SIRTF or
KH-12 repairs,  or LDEF 2-3 (Not that it's programmed).

Besides,  given the high probablity of a SHuttle Loss and
Fleet shut-down,  would you not want to be able to continue
Logistics flights from somewhere?

If we take Hurricane LeRoY,  and it seriously screws up
KSC for a couple months,  it would be very useful to have
an alternate launch site open.

A high Inclination orbit, does not require  we actually
buy any russian flight services.  it merely makes it possible.


|>2)  Improved Earth Observation Missions.
|
|This one actually makes sense, but the proponents of the
|high-inclination orbit seem to hardly ever mention it or the actual
|improvement that could reasonably be expected in return from it.
|

What can I say.  THis is the one I hear a lot about.  51 degrees,
just about doubles the earth observations science.


>>3)  Improved Logistics Flow missions.
>
>Unless this is just another way of stating something like 1, it
>doesn't seem particularly obvious to me why this would be so.
>

It means,  you have an opportunity for  more flights in less time.

KSC can only process N flights per year.  Vandenburg does not
launch  to 28 degrees.   Let's  say SSF desperately needs a
smoke shifter,  a rapid launch from Pletkesk (sp)  or baikonur
is possible.  It certainly is not from KSC.  I doubt KSC could push
a critical launch through in less then 30 days.

If you are going to do some serious materials processing in Orbit,
you want to get re-supply missions  often.  That means either some
real big improvements at KSC and risk of single point failure,  or
the option to do launches out of several space-ports.


>>4)  Improved space science/engineering base.  (  hihg inclination,
>>is a far more rigorous environment then low inclination.
>
>This sounds like saying "We should do it this way because it is
>*harder*."  Somehow, that doesn't quite track for me.
>

You learn more about working to solve hard problems then easy problems.
High Inclination  acts as a driver towards STS getting the AL-LI
ET  and the ASRM,  really not bad ideas in my book.
High Inclination, means they work  on radiation resistant systems.
a interesting engineering problem.


>>5)  Apparently ACRV return is simplified( This is what i was told,
>>    I can't see an intuitive reason why this is).
>

Henry explained this one for me.  thank you oh, lord of space lore.


>>Make vs Buy is  properly cognizant of the benefits of
>>Technology developement.   Nevertheless,  Every company does
>>Make this  decision in it's business operations.
>
>Yes, and generally badly, since companies often fail to look at
>anything too far beyond the next balance sheet.
>

Just because make vs buy is badly done, by most companies
doesn't mean there is anything wrong with the process,  it's
a problem with the people.

>>IBM  Buys  Micro-processors.  DEC buys 4M DRAMS.
>
>Yes, and we can both see how healthy *those* two are, can't we?
>

WOuld they be healthier  if they were  pouring money into
large IC Fabrication plants every year?  DEC can't afford more then
one large design project at a time,  do you think they could do more
after pouring money into a DRAM plant?

And IBM used to do everything in-house,  and it left them technologically
adrift come the 80's.  They had drifted so far from the main-stream
they had no products to sell to the other electronics firms.

The only way they could develope a PC, was to buy entirely from
outside sources.


>>Certainly there are intangible benefits from  spooling up to
>>do things,  but if that bleeds off developemnt  money from
>>more vital activities,  that is equally a problem.
>
>>Good Business people  make these analyses.
>

Japanese companies have poured enormous amounts of money into
low profit activities,  it has left them in a very difficult position.
It is somewhat un-certain if their  gamble has paid off.


>
>>More energy Conservation,  Higher energy taxes,  developemnt of
>>low energy consumption Infra-structure.   It's  bizarre, that it
>>is  cash wise cheaper for me  to drive  to Chicago  then to
>>take the train  ( The absolute lowest energy cost solution.
>
>It's actually not, if you properly amortize the vehicle the way the
>trains have to.  This is one of the points of 'full costing' (in the
>economic sense).  Lots of people make bad decisions because they
>figure that they already own the car so the cost of operating it
>(other than gasoline) doesn't count.
>

Oh, I know.  the actual full costing says take the bus,
especially when pollution is factored in,  but as an individual
consumer,  make vs buy,  says it's cheaper for me to
drive.


--

God put me on this Earth to accomplish certain things.  Right now,
I am so far behind, I will never die.

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

Date: 19 Jul 93 17:01:04
From: Steinn Sigurdsson <[e-mail]>
Subject: Hubble, Why the hurry?
Newsgroups: sci.space

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

   In article <[e-mail]> [e-mail] (Peter Monta) writes:
   >So, naive question, but why aren't laser-interferometric gyros used?
   >With good diode lasers available, plasma-tube lifetime/fragility
   >would be moot.

   I believe diode lasers don't produce a sufficiently clean output to be
   used in orthodox laser gyros yet.  And laser gyros qualified for combat
   aircraft don't need much improvement in durability to be good enough
   (in that department) for spaceflight.

Hmm, "reliable sources" [ouch, I'm starting to sound like Allen],
have told me that diode lasers are used in laser gyro designs,
they won't tell me if the gyros are good enough to go into
certain large US government payloads though, although from
the context I gathered that was the whole point...
on the other hand they could be still stuck to labtop assemblies
for the high-precision needed in this case.

In either case the HST design was frozen way before that kinda
stuff was available...

*  Steinn Sigurdsson                Lick Observatory         *
*  [e-mail]               "standard disclaimer"      *
*  I can take the killing, I can take the slaughter        *
*  But I don't talk to Sun reporters     - B.B. 1983        *

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

Date: 20 Jul 1993 02:20:23 GMT
From: Timothy Banks <[e-mail]>
Subject: Hubble, Why the hurry?
Newsgroups: sci.astro,sci.space

[e-mail] (Henry Spencer) writes:
>I'm told that the Hubble gyros weren't particularly
>advanced even by the standards of the time; there are better mechanical
>gyros, never mind laser types.

    At a recent conference I went to, several of the presentations
    involved HST data. One of the speakers commented on the gyro
    problem, and said that they were "left overs from IUE". I'm
    afraid I haven't confirmed this...



--
  Timothy Banks, Physics Department, Victoria University of Wellington, NZ.
bankst@kauri|rata|matai.vuw.ac.nz, banks@beagle|vavatch|solotol.phys.vuw.ac.nz
    "He's dead, Jim!" "OK, you take the tricorder, I'll take the wallet!"

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

Date: 20 Jul 93 03:33:51 GMT
From: Pat <[e-mail]>
Subject: Hubble, Why the hurry?
Newsgroups: sci.astro,sci.space

 SPectrum magazine did a really interesting re-view of
Laser Gyros  and FOG's  a few years back.

From what I remember,  Both of these,  suffer from an
in-sensitivity to small outputs.  this is worked around
by mechanically biasing the system,  of course that undercuts
a major elegance  of optical gyros.

I don't think the radiation problem  is that bad,  one could
always  shield the system,  i just wonder if they are
actually sensitive enough.  although David's mention of
planned replacements,   seems to grant an answer.

pat
--

God put me on this Earth to accomplish certain things.  Right now,
I am so far behind, I will never die.

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

Date: 20 Jul 1993 00:29:23 GMT
From: George William Herbert <[e-mail]>
Subject: Isp of solid fuels
Newsgroups: sci.space

[e-mail] (Bertil Jonell) writes:
>  Does anybody know some typical specific impulses for solid rocket fuels,
>both theoretical and practical? My references are mostly concerned with large
>scale rocketry so they don't list anything lower than the Isp's for various
>liquid propellant mixes.

Hi Bertil; here's a quick table for optimum expansion 1000 PSI chamber
pressure solid rockets

Materials            Isp SL, seconds
---------            ---------------
Galcit (asphalt/perch.)        240
perchlorate/plastic mixtures    270-275
Double-Base (nglycerine/ncell.)    270-280
SRB    (perch./plastic/al)    283

This is off the top of my head, so I may have some detail errors.
It's what I remember from the table in the Space Handbook, USAF University.

Note that the SRB mixture, Ammonium Perchlorate in a plastic base with
aluminum fuel added in, is standard in all launch vehicle large motors
under varying names with slightly different characteristics.  The Shuttle
solid boosters, the Titan boosters, the Castor motors, the Arianne solid
boosters, and the new Arianne 5 and H-2 boosters all use nearly the
same mixture, and all get Isp around 280.

-george william herbert
Retro Aerospace

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

Date: 16 Jul 93 04:00:06 GMT
From: [e-mail]
Subject: LRDPA & Return to the Mo
Newsgroups: sci.space

DA>>The Lunar Resources Data Purchase Act, soon to be introduced in
DA>Congress
DA>>(fingers crossed) uses private vendors to supply NASA with a
DA>geochemical
DA>>lunar map.

DA>>The LRDPA will pass the 103rd Congress if enough folks stop wishing
DA>about a return to the Moon, and actually *do somthing* about it.

BY>While LRDPA sounds like a good idea, I'm curious whether its
BY>supporters actually believe that this will lead to a manned return to
BY>the moon -- and if so, how?


Well, I'm glad that you asked that question (typical response from a
politician fishing for an answer to a tough question).

1) After 21 years of political gridlock, squabbling among scientists, and
just plain idiocy, *any* lunar survey is a step in the right direction. If
we delay too much longer in lunar exploration, the current generation of
lunar scientists - those that cut their teeth on Apollo data - will fade
away, leaving the next generation with no new data set to examine. Let's
face it - how many grad students opt to be lunar scientists these days? A
new lunar mission would go far in turning around the cultural state within
the Beltway as to the chances for further lunar exploration, robotic and
manned. As they say - the first step is the hardest.


2) The procurement method outlined in the bill will allow for more
affordable exploration in the future, both robotic and unmanned. With
enormous budget deficits looming down the road, unless we come up with
affordable missions, we will have no missions.



___ WinQwk 2.0b#0

--- Maximus 2.01wb

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

Date: 20 Jul 1993 00:54:06 GMT
From: George William Herbert <[e-mail]>
Subject: Mars Direct Info
Newsgroups: sci.space

[e-mail] (Ralph Buttigieg) writes:
>Some of my BBS users would like to know more about Zubrin's Mars Direct
>proposal. Are there any sites out there with articles, drawings etc? Failing
>that, can anyone inform me of a contact address for Mr Zubrin? A E-Mail
>address would be nice. I could then write to him and ask for permission to
>make available some of his articles on the BBS.

Zubrin isn't on the Net.  He is, for internal Martin Marietta purposes
only*, but not for outside email.  And unfortunately I don't know of
any versions of his papers online... which is _very_ unfortunate.

That having been said, there are at least two of us here on sci.space
(myself and Frank Crary) who've been following Mars Direct pretty
closely for several years and who have seen the papers on it.
It was (suprise) again a featured item at Case for Mars V earlier this
year, and hasn't changed much except that Bob's talking more certainly
about using artificial-G on the way out by tethering to the expended
upper stage, or at least that's the impression I got.

If you'd like to ask us questions about it, or have one of us do a
summary article or something on the concept (and one should be posted
here sometime, also one on the Stanford/Energia** proposal) we can work
on that.

-george william herbert
Retro Aerospace

*  I have Bob Zubrin's snail mail address somewhere, and will email it to
   anyone who promises not to take too much of his very valuable time 8-)
** Prof. Bruce Lusignian of Stanford is primarily behind this one, a mission
   very similar to Mars Direct except not using in-situ resources (less risk)
   and using more NASAish costing estimates for the project.  Uses the Energia
   launcher instead of a Shuttle-C concept (Mars Direct uses a shuttle-derived
   HLV named Aries).

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

Date: 16 Jul 93 04:00:08 GMT
From: [e-mail]
Subject: Nitpicking
Newsgroups: sci.space

BH>Nitpicking: Twenty, as of June 1993, since Explorer 49 orbited the
BH>Moon. Much less if "we" are mankind, thanks to the Soviet Luna probes
BH>and Hiten (launched 1/24/90).

Thank you for the nitpicks. I believe Henry also caught me on these
details.

Actually, Explorer 49 was *not* a lunar probe in the usual sense: it
literally ignored the Moon (that's why it worked).


--- WinQwk 2.0b#0

--- Maximus 2.01wb

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

Date: 19 Jul 1993 21:42:59 -0400
From: Pat <[e-mail]>
Subject: Very basic questions about dark matter
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Bill Higgins-- Beam Jockey) writes:
>Remember a fundamental equation of cosmology:
>
>(Exotic explanations            (Employment for
>      for              =            people
>  missing mass)                    like me)


Does this mean, if we don't support  your 12 Billion dollar
SSC (  not very far from STS or SSF)  you will
actively lobby against our DC-X  :-)

pat

--

God put me on this Earth to accomplish certain things.  Right now,
I am so far behind, I will never die.

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


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From: David Ward <[e-mail]>
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Subject: Re: COOKIE CUUTTER PROBES (WA
Date: 19 Jul 1993 19:11 EST
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In article <[e-mail]>, [e-mail] (Zvi Lev) writes...
>Henry Spencer ([e-mail]) wrote:
>
>: Who cares?  Pick the one that's best at initial design time, and stick
>: to it.  It's not that vital to have the latest and fastest CPU aboard --
>: you're not running Microsoft software. :-)
>
>That is, of course, very true. However, I want to use it to bring up an
>idea and see what people think about it:
>
>I want you to make me a personal computer, and it does not have to be faster
>or more sophisticated than standard ones, except for the next few items:
>
>F. (and if E was a catch, this is a black hole!) - eh, sorry guys,
>but I only want a few of these ever produced, say 5, and no, you cannot
>use this technology to make anything that sells.
>

Of your reasons, I think this one's really the killer.  As a matter of
fact, if you get to 5 units, you might consider yourself lucky to have
a "production line"-quantity unit.

>
>Actually, it is even worse - I do not believe that the software
>of any spacecraft is anywhere as reliable as that of any old (5 years),
>popular PC operating system. No matter how clever the people who test it
>are, they are not cleverer than 10^7 users with crazy setups and uses.
>The same for hardware, of course...
>
Agreed, but then you usually test the crazy setups and uses on a space
program on the ground before you use it.  Also, you generally don't have
to tell a spacecraft's Flight Ops Team to Read the Manual (RTFM) very
often.
>
>So, is there a way out? I dunno, but consider this:
>suppose you could buy for around 100k$ a system which enables you to
>fully build a sattelite main electronics system on something which is
>PC compatible (no advertising intended. Could be any kind) -
>that is, you can run on it anything a PC runs, plug into it any card
>a PC can take.    The system has all the excellent debugging
>facilities you have for a PC, but with an operating system that also
>supports some clever features such as redundancy, SEU protection,
>ACS sensors/actuators support,etc. The thing also has a simulation
>mode that can feed the desgined electronics/software inputs to match
>a space enviro.
>
>I may be optimistic, but I think such a thing could solve many problems
>for many many missions, if it is done correctly, with the right tradeoffs
>between actual needs (mission,reliability) and the ever present
>GEE WHIZ desire (lets develop a NEW way to do it that is 10% better than
>the old one but costs double the money.. this should get us publicity...).
>
>Basically i guess I am saying that we might have a use for a space
>hardware bus that runs Microsoft windows.....
>
FYI, Goddard's Engineering Directorate is currently building two
spacecraft that use an 80386 microprocessor for main functions.
No DOS or Windows though.:-)

>
>What are the opinions of my fellow USENET space advocates?
>If you want to mail me directly - I'm
>at [e-mail]
>Ever yours,
>Zvi Lev
>

David W. @ GSFC

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End of Space Digest Volume 16 : Issue 896