Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V15_4/V15NO455.TXT

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Date: Wed, 25 Nov 92 05:05:51
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #455
To: Space Digest Readers
Precedence: bulk


Space Digest                Wed, 25 Nov 92       Volume 15 : Issue 455

Today's Topics:
                        Ariane launch coverage
                     Camera Aspect -- What is it?
                         Dante on "Nightline"
                        GPS handheld receivers
                      Magellan Update - 11/20/92
    New Gaspra data, Earth pix (was Re: Galileo Update - 11/24/92)
                   Pumpless Liquid Rocket? (2 msgs)
      Reflights of ASTRO (was Re: Shuttle replacement) (2 msgs)
                      Shuttle Computer Problems
                     Shuttle replacement (3 msgs)
                              Simplicity
                    Space suit research? (2 msgs)
                           Stars listing...
                Voltage protection (re: Mars Observer)

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Date: Wed, 25 Nov 92 01:24:35 EST
From: John Roberts <[e-mail]>
Subject: Ariane launch coverage

-From: [e-mail] (Dean Adams)
-Subject: Ariane v.55 Mission Data
-Organization: Nyx, Public Access Unix at U. of Denver Math/CS dept.
-Date: Mon, 23 Nov 1992 06:19:45 GMT

-ARIANESPACE FLIGHT 55
-...
-LAUNCH COVERAGE:

-All Ariane missions are broadcast live via satellite from Kourou.
-Coverage begins at 30 minutes before launch and continues until
-all payloads have been deployed.

Is the Ariane satellite launch coverage in NTSC, PAL, or SECAM format?

(Come to think of it, how about the CIS video?)

John Roberts
[e-mail]

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

Date: Tue, 24 Nov 1992 21:55:47 GMT
From: Jeffrey J Bloch <[e-mail]>
Subject: Camera Aspect -- What is it?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Charles Fletcher) writes:
>The title says it all--Could someone give me a definition of "Camera Aspect"
>as it relates to satellite navigation. Any references would also be helpful.
>
>Thanks in advance,
>
>Charlie
>
>
>
>
>--
>    NeXTMail to:        |    ...to confer, converse, and
>    [e-mail]    |    otherwise hobnob with my
>                |    brother wizards.
>

I think you are refering to "Camera Aspect Solutions". Many space astronomy
experiments need to know exactly where they are pointing in the sky at any
given time. In essence, pictures of the sky in the direction one's experiment
is pointing are taken periodically. One then fits the positions of known stars
in the images to determine an "aspect solution". This has been done many ways.
Some systems do this in real time with CCD cameras and a lot of computing
power on the satellite. Many shuttle and sounding rocket experiments actually
use film cameras and the film is analyzed on the ground along with the
experiment telemtry to determine the attitude solution after the fact.


                            Hope This Helps,
                            Jeff Bloch
                            Astrophysics and
                              Radiation Measurements
                                Group
                            LANL

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

Date: Wed, 25 Nov 92 01:31:48 EST
From: John Roberts <[e-mail]>
Subject: Dante on "Nightline"

The Tuesday night edition of "Nightline" featured Antarctica, and showed
some video of the Dante rover. It looks like an enormous (purple, of course)
spider when it moves.

Also shown was the NASA submersible robot. That has a really nifty camera
control system - the operator wears a "virtual reality" headset, with
motion or position sensors built in. When he moves his head, the camera
platform swivels correspondingly. (I assume the images are stereo.)

John Roberts
[e-mail]

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

Date: Tue, 24 Nov 1992 22:36:33 GMT
From: Dillon Pyron <[e-mail]>
Subject: GPS handheld receivers
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Dave Hopkins) writes:
>Is the market for GPS handheld receivers is really as big as we've been
>lead to believe? What use will long, lat and alt be to anyone unless it
>it is fully integrated into a navigation system?
>

Rocks is still rocks, regardless of the position determining technique.  I was
pleased to find that my sextant readings for the last six months were within
20" (seconds, not inches) of the readings from my GPS, taken during Op Desert
Storm.  If you are flying, it's nice to know that your present altitude really
will put you over the minimum terrain altitude.

Navigation was done, quite well, prior to computers.  And there are many
sailors who leave port with nothing more than a sextant and a good clock (and
the almanacs and tables).
--
Dillon Pyron                      | The opinions expressed are those of the
TI/DSEG Lewisville VAX Support    | sender unless otherwise stated.
[phone] (when I'm here)     |
[phone] (when I'm home)     |"Pacts with the devil are not legally
[e-mail]          |binding!"
PADI DM-54909                     |-Friar Tuck   _Robin Hood:The Hooded Man_

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

Date: 24 Nov 92 10:30:36 GMT
From: hiroki hihara <[e-mail]>
Subject: Magellan Update - 11/20/92
Newsgroups: sci.space,sci.astro

In article <[e-mail]> [e-mail] writes:
>In article <[e-mail]> [e-mail] (Claudio Egalon) writes:
>>I have a question about the aerobraking maneuver that the Magellan
>>will perform; Is there any possibility that any of the components of
>>the Magellan be damaged during this maneuver??? ...
 ...
>Hiten performed some aerobraking experiments through the Earth's atmosphere
>in March 1991.

Temperature on bus equipments increased almost fifty degree, and
no anomaly was reported at that time.  (I don't know about mission
equipments, because many of them are not our design. :-)  )

Hiten is working very well even after the re-entry, so scientists
in ISAS hit upon a new plan.  It made another swing-by, and is
turning around the moon now.

We procured many parts from the United States for Hiten, and they
are proven to be strong enough against such environment.
Therefore, I think the trial of Magellan will success.


-- NEC Space Systems Development Division
   $B1'Ch3+H/;v6HIt!!Ek:\5!4o3+H/It(J
   Hiroki Hihara
   $B[X86(J $B90<y(J

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

Date: 25 Nov 92 01:38:39 GMT
From: Bill Higgins-- Beam Jockey <[e-mail]>
Subject: New Gaspra data, Earth pix (was Re: Galileo Update - 11/24/92)
Newsgroups: sci.space,sci.astro

In article <[e-mail]>, [e-mail] (Ron Baalke) writes:
>                             GALILEO STATUS REPORT
>                               November 24, 1992
>      Yesterday, the Gaspra data playbacks were performed, [...]
>      Today, November 24, 1992, Gaspra data playbacks are scheduled [...]
>      Tomorrow, Gaspra data playbacks are scheduled along with [...]

Oh, boy, oh boy.  I know what should be in there.  One low-res
six-color image, and a number of others, showing Gaspra fuzzier than
we've seen it before, but at least some detail on the "back side" we
haven't seen yet.  Full infrared imaging spectrometer data, good for
composition analysis and quantitative thermal modeling.  Other data
from the Gaspra encounter last year that have been sitting quietly on
Galileo's tape recorder.

Wonder when we'll get to see any of these data?

Earth encounter two coming up on 8 December.  Hope Galileo doesn't
smack into Toutatis.  We should see more pix of Earth and Moon on TV
in the days afterward, maybe including the movie of their motion
(don't get excited, the Moon will only be a few dozen pixels across;
and it's real dark compared to the Earth, so it will be hard to
capture them in the same scene without overexposing Earth or
underexposing the Moon).

Then in late December and early January, more thermal cycling of the
high-gain antenna mast, combined with "hammering" from the mechanism
that attempts to open the HGA.  Maybe the ribs will pop.

Now that I think about it, I suppose they'll probably show us the new
Gaspra images at the post-encounter press conference.  Better alert my
pal to fire up his satellite dish and VCR...

Bill Higgins, Beam Jockey              |
Fermi National Accelerator Laboratory  | "Get the dinosaurs in, Martha,
Bitnet:           [e-mail]  |  they're predicting comets."
Internet:       [e-mail]  |      --Dr. Barry D. Gehm
SPAN/Hepnet:           43011::HIGGINS  |

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

Date: Tue, 24 Nov 1992 21:06:02 GMT
From: Henry Spencer <[e-mail]>
Subject: Pumpless Liquid Rocket?
Newsgroups: sci.space

In article <schlegel.722562761@cwis> [e-mail] (Mark Schlegel) writes:
>>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.

Straightforward in theory... but in practice, conventional rockets (which
lack this particular instability but have others) often have problems with
such things, computer-controlled valves and all.  Such problems may not be

unsolvable but they aren't necessarily trivial.
--
MS-DOS is the OS/360 of the 1980s.      | Henry Spencer @ U of Toronto Zoology
              -Hal W. Hardenbergh (1985)|  [e-mail]  utzoo!henry

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

Date: 25 Nov 92 00:10:21 GMT
From: "G. Scott Smith" <[e-mail]>
Subject: Pumpless Liquid Rocket?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (David Toland) writes:
>In article <schlegel.722562761@cwis> [e-mail] (Mark Schlegel) writes:
>[e-mail] (Henry Spencer) writes:
>
>>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.)

Some spacecraft use a pressure feed system for the attitude control thrusters.
But there you don't have the high thrust requirements, thrust levels range from
5 to 20 lbf of thrusts, Isp 250 or 300.  Although the Gravity Probe B has a
feed system that take the helium that boils off the dewar that holds the
experiment and uses that for attitude control, the thrusters, which are
variable thrust, are measured in micronewtons.

I think essentially, for high performance engines, you need the turbo pumps
mainly for the volume of fuel that the engines need for the thrust output, not
just to get the fuel to the combustion chamber.

--
Scott Smith                     |Ozman's First Law: If someone says he will do
                                |                   something "without fail",
                                |                   they won't.

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

Date: 24 Nov 92 16:58:03 -0600
From: Bill Higgins-- Beam Jockey <[e-mail]>
Subject: Reflights of ASTRO (was Re: Shuttle replacement)
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Pat) writes:
> In article <[e-mail]> [e-mail] (Gary Coffman) writes:
>>
>>Spacelab and Astro are two payloads that we want very much to return
>>from orbit on a regular basis. That allows them to be easily refitted
>>with new experiment racks and reflown.
> I think astro only returns because the shuttle returns.  Most astro
> program objectives could be flown on expendable sattellites rather
> like IUE.  [...] if ASTRO was so great, they'd fly it more.

Hmmph.  I'd like to hear Greg Hennessey's opinion on this, Pat.

ASTRO (a bunch of telescopes in the .5 m to 1 m class working mostly
in the ultraviolet) made sense if you flew it frequently, like every
year or two.  They were stupid if you flew them just once after a
decade of development, which is what has happened so far.
(Fortunately, they're scheduled for an ASTRO-2 reflight, and I hope
they do more).

They are similar to the fully-automated satellite IUE (International
Ultraviolet Explorer) but IUE is pretty much a spectroscopy mission,
where ASTRO had (1)a 1-m spectroscopic scope with far-ultraviolet
capability, (2) the world's first imaging UV telescope in orbit, (3) a
dedicated photopolarimetry scope.  Plus NASA threw in a couple of
X-ray telescopes on the same mission.  They also incorporate

Would it make sense to put the ASTRO telescopes onto one or more
free-flying platforms?  Well, it would be a pain to do *now*, and
maybe not cost-effective, since they're designed to run from the
Shuttle. (For instance, UIT uses film, not CCDs, so you have to bring
it back.)  Hey, Greg, do your guys ever talk about how to do this?

But suppose it's 1980 and you're running this project. A gypsy
fortuneteller gives you a glimpse of the Shuttle's troubles and
ASTRO's electronics problems once it *does* fly (the primary and backup
control computers both crapped out and a manual kluge was created for
pointing)-- well, you would dash out and buy a free-flyer
faster than you could say "Son of IUE."

Or am I all wet?

> Space lab is useful, certainly, but you could automate it and fly most of
> the experiments on disposables with return capacity if you really wanted.
> certainly the shuttle has certain unique capacities but judging how often
> LDEF, ASTRO and SPacelab have flown over the last 12 years,  i dont think
> people are dying for those missiions.

Aaarrgh.  Are you saying ASTRO and other Spacelab missions have flown
infrequently because they have little scientific merit?  *I* think
they've flown infrequently because the Shuttle has flown infrequently!
As I said, they were conceived when frequent reflights were supposed
to be part of the Shuttle science program.

Bill Higgins                           | Sign in window of
Fermi National Accelerator Laboratory  | Alice's bookstore:
Bitnet:      [e-mail]       | "EVER READ BANNED BOOKS?
Internet:  [e-mail]       |     YOU SHOULD!"
SPAN/Hepnet:      43011::HIGGINS       | Gee, I hope it doesn't become
                                       |   *compulsory*.

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

Date: Tue, 24 Nov 1992 23:42:00 GMT
From: Greg Hennessy <[e-mail]>
Subject: Reflights of ASTRO (was Re: Shuttle replacement)
Newsgroups: sci.space

Bill Higgins writes:
#Hmmph.  I'd like to hear Greg Hennessey's opinion on this, Pat.

Sure. I would have chipped in earlier, but for some reason sci.space
got unsubscribed.

#ASTRO (a bunch of telescopes in the .5 m to 1 m class working mostly
#in the ultraviolet) made sense if you flew it frequently, like every
#year or two.  They were stupid if you flew them just once after a
#decade of development, which is what has happened so far.
#(Fortunately, they're scheduled for an ASTRO-2 reflight, and I hope
#they do more).

There is no doubt that *all* four of the telescopes in the Astro
mission would be much better off as IUE type projects, but the screwey
budget situation does not allow this. BBXRT is basically being done as
a permanent telescope as ASTRO-D, but the three UV telescopes are SOL.

If the three UV instruments, WUPPE and HUT (one a spectro-polarimeter,
the other a spectroscope mainly from 912-1216 AA, but can go down to
450 AA), are easily convertible in scope to IUE type instruments, BUT
NOTE, that isn't saying that the existing instruments would be
converted. It is probably just as expensive to retrofit the existing
instruments as it is to design new ones. I'm not very familar with how
much HUT overlaps with the FUSE mission, so that one may not be very
useful.

UIT is a bit harder. I have the origional proposal on my desk, and it
is dated 1978. *AT THE TIME* it was clear that using film as a
recorder was far better than CCD's, especially considering the 40 mm
field of view. There is an announcement of opportunity for Small
Mission EXplorer instruments, and it is highly likely that a UV survey
instrument (using a mosiac of 2Kx2K CCD's) will be chosen. This would
do an all sky survey, then deeper direct pointings for the rest of the
spacecraft's life.

#where ASTRO had
#(2) the world's first imaging UV telescope in orbit,

Sorry, not true. HST beat us to orbit, and FAUST also flew before us,
and there were some UV wide field imagers on some of the Apollo
missions. Most of them returned of order 10 or so images, while UIT
returned 900 exposures, but we weren't the first.

#(For instance, UIT uses film, not CCDs, so you have to bring
#it back.)  Hey, Greg, do your guys ever talk about how to do this?

Only at bars while drinking, since 1) there is no hope for a budget
for this, 2) using CCD's would lose a large fraction of the field of
view, and 3) there is no hope for a budget for this.

Also add in the lack of a budget, and you see it isn't feasable.

#But suppose it's 1980 and you're running this project. A gypsy
#fortuneteller gives you a glimpse of the Shuttle's troubles and
#ASTRO's electronics problems once it *does* fly (the primary and backup
#control computers both crapped out and a manual kluge was created for
#pointing)-- well, you would dash out and buy a free-flyer
#faster than you could say "Son of IUE."
#
#Or am I all wet?

Well, in 1980 the scientists were *TRYING* to get Son of IUE, since we
knew the shuttle was bad for science, but there was no budget. It was
the shuttle or nothing. The astronomers didn't have to pay for a
shuttle launch, but would have to pay for a unmanned rocket launch, so
it was either launch on the shuttle, or watch someone else launch on
the shuttle. Also remember that IUE wasn't paid for untill *AFTER*
"Large Space Telescope" aka HST was ordered. IUE was basically a
proving ground for much of HST, not the first of a series of
telescopes it *SHOULD* have been!

#Aaarrgh.  Are you saying ASTRO and other Spacelab missions have flown
#infrequently because they have little scientific merit?  *I* think
#they've flown infrequently because the Shuttle has flown infrequently!

They were designed when the shuttle was going to fly 24 times a year,
so they would fly once every 24 flights. According to schedule,
Astro-2 will fly on about the 60th flight, basically on schedule. :^(



--
-Greg Hennessy, University of Virginia
 USPS Mail:     Astronomy Department, Charlottesville, VA 22903-2475 USA
 Internet:      [e-mail]
 UUCP:        ...!uunet!virginia!gsh7w

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

Date: Tue, 24 Nov 92 20:40:24 EST
From: John Roberts <[e-mail]>
Subject: Shuttle Computer Problems

-From: [e-mail]
-Subject: Shuttle Computer Problems
-Date: 24 Nov 92 03:59:56 GMT
-Organization: NASA, Kennedy Space Center

-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?

It's known that even very high-energy cosmic rays occasionally reach the
ground. Another possibility that occurs to me: as well as I can recall
from the post-recovery analysis of LDEF, the typical radiation dosage
in LEO is a few hundred times what is normally experienced on the ground.
(It's considerably less inside the Shuttle, but still above ground levels.)
Many materials that are exposed to radiation themselves become radioactive,
some more than others. Though I get the impression that this form of
secondary radiation is usually not very energetic, it still might be
adequate to explain a higher-than-expected incidence of SEUs on the ground,
particularly if the IC packages themselves are what's become radioactive.
Have there been any attempts to measure radiation levels? (Particularly
right after landing.) Are the memory chips in ceramic or plastic packages?

-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).

I've read that both the trend toward smaller memory cell sizes and the
ongoing reduction of operating voltage from 5V to 3.3 or 3V are expected
to increase the susceptibility of computer logic to SEUs, other things
being equal. So lower voltage during powerdown *might* be a contributing
factor.

John Roberts
[e-mail]

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

Date: Tue, 24 Nov 1992 21:43:15 GMT
From: Henry Spencer <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Gary Coffman) writes:
>>... as any Harrier pilot will tell you, a vertical powered landing is
>>safer than a horizontal powered landing.  And either one is *much* safer
>>than a Shuttle-style horizontal landing *without* power.
>
>As any glider pilot will tell you, gliders don't burn on impact. Nor
>do they pinwheel across the sky when a thrust diverter fails.

Ask any airline pilot how he'd prefer to land a 747:  as a glider with
tanks bone-dry, or low on fuel but with all four engines running.

If gliders were big enough and heavy enough and fast enough to need
10,000ft concrete runways for a safe landing, most of them would have
engines, so they could abort a landing approach and go around for
another try.

No, gliders don't burn on impact; they just go "crunch".  It's still
just about as fatal.

Neither airliners nor rockets "pinwheel across the sky when a thrust
diverter fails".  A Titan launch a few years ago had one of the core
engines lose gimbal control and lock in position (just about hard over
to one side, I believe it was); the other engine compensated and only
the technical crew noticed -- the launch was successful.
--
MS-DOS is the OS/360 of the 1980s.      | Henry Spencer @ U of Toronto Zoology
              -Hal W. Hardenbergh (1985)|  [e-mail]  utzoo!henry

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

Date: Tue, 24 Nov 1992 21:50:52 GMT
From: Henry Spencer <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Chris Jones) writes:
>All US missions up through the fourth shuttle launch had crew escape
>provisions.  After the loss of Challenger, the escape pole was added to the
>shuttle, so there were 21 missions flown with no escape provisions after
>launch, and I'd say that the shuttle currently has no escape provision during
>boost.

More precisely, the shuttle has never had any provision for escape during
boost.  Both its escape systems -- the ejection seats carried for the first
four flights, and the escape pole carried now -- require gliding flight at
relatively low altitude.  (Technically the seats could have been used during
boost, but the probability of survival approached zero.)  Both were meant
as alternatives to a (probably unsurvivable) ditching or belly landing,
not for instant escape during powered flight.

>>             I cant remember wether apollo used a escape rocket
>>or the SM engines,
>
>It had an escape rocket.

Actually, it used either one, depending on timing.  The escape rocket
was jettisoned after it was no longer needed.
--
MS-DOS is the OS/360 of the 1980s.      | Henry Spencer @ U of Toronto Zoology
              -Hal W. Hardenbergh (1985)|  [e-mail]  utzoo!henry

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

Date: Wed, 25 Nov 1992 02:22:05 GMT
From: "Simon E. Booth" <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Gary Coffman) writes:
>In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>>In article <[e-mail]> [e-mail] (Allen W. Sherzer) writes:
>>>>the idea of a powered descent and vertical
>>>>landing gives me the willies...
>>>
>>>Much safer than airplanes for most people. A DC crash will only affect the
>>>Spaceport. When aircraft crash they tend to kill people on the ground.
>>
>>And as any Harrier pilot will tell you, a vertical powered landing is
>>safer than a horizontal powered landing.  And either one is *much* safer
>>than a Shuttle-style horizontal landing *without* power.
>
>As any glider pilot will tell you, gliders don't burn on impact. Nor
>do they pinwheel across the sky when a thrust diverter fails.
>
Most gliders have no fuel on board. The shuttle, however has a considerable
amount of hypergolic fuels on board for the OMS and RCS thrusters.
Which means a big explosion w/toxic gas clouds, as well as the loss of the
crew.

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

Date: Tue, 24 Nov 92 20:48:41 EST
From: John Roberts <[e-mail]>
Subject: Simplicity

-From: [e-mail] (Allen W. Sherzer)
-Subject: Re: Shuttle replacement
-Date: 24 Nov 92 15:19:15 GMT

-If your in Shuttle, true enough. On the other hand if your in a Delta
-Clipper made of much simpler components (less likely to fail) and with
-abort modes throughout the entire flight envelope it is a great deal
-of comfort.

I'd say that's a little bit too strong a statement, in the general case.
Reliability is dependent on many factors, of which simplicity is only
one. If you took all the redundant components out of the Shuttle, it
would certainly be simpler, but it would probably be *less* reliable.
If Magellan had been made slightly more simple, it would have failed
almost immediately, and we wouldn't have all those radar images. Of course,
the proper way to apportion complexity is open to debate.

-Simplicity often = safety.
            -----

That's more like it. :-)

John Roberts
[e-mail]

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

Date: Wed, 25 Nov 1992 01:40:50 GMT
From: Bruce Dunn <[e-mail]>
Subject: Space suit research?
Newsgroups: sci.space

> John Roberts writes:
>
> Apparently anything significantly below 3 psi partial pressure of oxygen
> is a potential health risk, unless you have many generations of ancestors
> who lived in the mountains. The body undergoes various changes to adapt to
> low oxygen content, but some of these changes have undesirable side
> effects.
> I'll try to find that Scientific American article again and post a summary.


        Another useful data point might be the experience at the Mauna Kea
observatories at ca. 15,000 feet altitude.  I believe that one of the
telescopes has oxygen-enriched working areas because of problems suffered by
astronomers who have not acclimatized.  Do any of our astronomer readers have
any information on this?

--
Bruce Dunn    Vancouver, Canada   [e-mail]

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

Date: Wed, 25 Nov 1992 04:45:43 GMT
From: Frank Crary <[e-mail]>
Subject: Space suit research?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Bruce Dunn) writes:
>> Apparently anything significantly below 3 psi partial pressure of oxygen
>> is a potential health risk, unless you have many generations of ancestors
>> who lived in the mountains.

I'm not sure what you mean by "significantly", but this certainly doesn't
apply to ~2 to 2.5 psi oxygen: The residents of Aspen, many (most?) of
whom have zero generations of ancestors who lived in mountains, live
and work at such oxygen pressures, with no visable problems. Further,
people with no hereditary _or_ personal adjustment to low pressures
routinely go they to ski (which, if anything, requires slightly above
normal consumption of oxygen.)

>        Another useful data point might be the experience at the Mauna Kea
>observatories at ca. 15,000 feet altitude.

This is more extreme than anything suggested for spacecraft cabins (Mauna
Kea had a total pressure of ~550 mbars/8psi and a partial pressure of
oxygen slightly around 1.5-1.7 psi.)

>I believe that one of the
>telescopes has oxygen-enriched working areas because of problems suffered by
>astronomers who have not acclimatized.  Do any of our astronomer readers have
>any information on this?

I've heard a few, but none of them concerned long term effects: After a
few days to adapt, people seem to do fairly well. There are a few who
can't adapt, but in the case of spaceflight, I don't see why this couldn't
be part of the medical qualifications. (Of course, the Russians use this
philosophy to select out people prone to the bends and thereby sidestep
the whole low-pressure cabin/pre-breath issue. Their advice, reportedly,
is "make sure your flight doctors know who they work for.")

                                                 Frank Crary
                                                 CU Boulder

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

Date: 25 Nov 1992 01:30:13 GMT
From: Ryan Mercer Davis <[e-mail]>
Subject: Stars listing...
Newsgroups: sci.space

I'm a Computer Science student working on a comuter graphics
project involving an immaginary space ship w/ about 1g accel
flying through the local star systems.  I intend to include color
shifts and other relitvistic effects.

the problem is, i need some stellar data:
    Stars within 100ly, their luminosity, mass, spectral class
    and motion (either spherical or orthogonal)

i'd appreciate any help as to where to find such info.
thanx.

--
_______________________________________________________________________________
                   [e-mail] |
   /\  /\                                |  Realism, n : Nature as seen through
  //\\//\\                               |               the eyes of a toad.
 //  \/  \\    A   C   B   E   T   H     |
//        \\  ----------=====}=====O     |  --- Open locks
"By the pricking of my thumbs,           |  --- Whoe'r knocks.
 Something wicked this way comes!"       | Send my opinions to /dev/null.

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

Date: Tue, 24 Nov 92 21:00:12 EST
From: John Roberts <[e-mail]>
Subject: Voltage protection (re: Mars Observer)

Remember all the trouble Mars Observer had with incorrect voltages being
applied during testing? Now a somebody at Lewis Research Center has
published a short description of some very simple circuits that can be
incorporated to guard against incorrect polarity and excessive voltage.
They're described on page 22 of the October, 1992 issue of NASA Tech Briefs.

(I wonder whether there's a connection? :-)

John Roberts
[e-mail]

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End of Space Digest Volume 15 : Issue 455
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