Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V15_4/V15NO413.TXT

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Date: Thu, 12 Nov 92 05:05:57
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #413
To: Space Digest Readers
Precedence: bulk


Space Digest                Thu, 12 Nov 92       Volume 15 : Issue 413

Today's Topics:
                   date for geminid meteor shower?
                      Japanese 1990 Lunar Probe
                  Japanese X-ray satellite: Astro_D
                      Low-Pressure O2 Atmosphere
                     Lunar "colony" reality check
             Lunar "colony" reality check and Apollo fire
                    Mars Simulation in Antarctica
                              newsgroups
                         Obscure Help Needed
                          oxygen atmospheres
                        Space suit research???
                Swift-Tuttle Comet a threat to earth?
                              Thumbs up
              What kind of computers are in the shuttle?

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

Date: Wed, 11 Nov 92 20:28:34 GMT
From: Stephen Kneuper <[e-mail]>
Subject: date for geminid meteor shower?
Newsgroups: sci.space

I was planning to watch the Geminid meteor shower this year but I'm
not sure what date I should plan for.

In the "stardate" publication put out by Univ Texas McDonald
Observatory, they metion the peak as 12 December...

In the space calendar, it mentions 14 December...

Any suggestions?  I know less than nothing about such events, I
thought I would start educating myself.  Should I watch in the evening
or morning?


--
Steve Kneuper                                [e-mail] - Internet
Sr. Operating Systems Specialist
University of Texas System (mailcode 78700)  kneuper@uthermes - BITNET
Center for High Performance Computing        [phone]

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

Date: Thu, 12 Nov 1992 04:31:57 GMT
From: Ron Baalke <[e-mail]>
Subject: Japanese 1990 Lunar Probe
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Karl Dishaw) writes...
>I saw a UPI dispatch saying that Japan launched two satellites to the
>Moon in January 1990, but there wasn't anything in the FAQ about them.
>Does anybody know what happened on that mission and whether they got
>any useful data?
>

I wrote this about the Japan probes a year and a half ago.  I've also
appended Yoshiro Yamada's post on a later lunar fly.

                            HITEN STATUS REPORT
                               March 8, 1991

     Japan's small Moon probe, Hiten, made its seventh lunar flyby on March 3,
passing about 13,300 km from the Moon.  JPL's Deep Space Network is tracking
the spacecraft.  On February 28, the 34 meter Goldstone antenna supported
ranging tests on Hiten, and were successful.  On March 1, the same antenna was
used to collect 24 minutes of ranging and doppler data.

     Hiten was launched into Earth orbit on January 24, 1990.  The spacecraft
was then known as MUSES-A, but was renamed to Hiten once in orbit.  The 430 lb
probe looped out from Earth and made its first lunary flyby on March 19, where
it dropped off its 26 lb midget satellite, Hagoromo.  Japan at this point
became the third nation to orbit a satellite around the Moon, joining the
Unites States and USSR.

     The smaller spacecraft, Hagoromo, will remain in orbit around the Moon.
An apparently broken transistor radio caused the Japanese space scientists to
lose track of it.  Hagoromo's rocket motor fired on schedule on March 19, but
the spacecraft's tracking transmitter failed immediately.  The rocket firing
of Hagoromo was optically confirmed using the Schmidt camera (105-cm, F3.1) at
the Kiso Observatory in Japan.

    Hiten will continue to make lunar flybys on a regular basis, typically
once a month.  According to Takahiro Yamada at ISAS,  Hiten will be performing
aerobreaking experiments on March 19 and 30.  These experiments will be done
using the atmosphere of the Earth.  The next lunar flyby is scheduled for
April 26.


                       Key Dates for Hiten
                       ----------------------------------------
                       01/24/90    Launch
                       03/19/90    1st Lunar Flyby,
                                   Separation of probe
                       07/10/90    2nd Lunar Flyby
                       08/04/90    3rd Lunar Flyby
                       09/07/90    4th Lunar Flyby
                       10/02/90    5th Lunar Flyby
                       01/27/91    6th Lunar Flyby
                       03/03/91    7th Lunar Flyby
                       03/19/91    1st Aerobraking Maneuver
                       03/30/91    2nd Aerobraking Maneuver
                       04/26/91    8th Lunar Flyby


Forwarded from Yohiro Yamada, Yokohama Science Center

                                 HITEN STATUS REPORT
                                  February 22, 1992

     Hiten (MUSES-A) made a close approach to the moon at 22:33 JST (UTC+9h)
on February 15 at the height of 423 km from the moon's surface (35.3N, 9.7E)
and fired its propulsion system for about ten minutes to put the craft into
lunar orbit.

The following is the orbital calculation results  after the approach:

    Apoapsis Altitude: about 49,400 km
    Periapsis Altitude: about 9,600 km
    Inclination    : 34.7 deg (to ecliptic plane)
    Period        : 4.7 days


(Source: February 17, 1992, Announcement by ISAS/Office of External Relations)

     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Give people a second
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | chance, but not a third.
|_____|/  |_|/       |_____|/                     |

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

Date: Wed, 11 Nov 1992 19:14:27 GMT
From: "John A. Nousek" <[e-mail]>
Subject: Japanese X-ray satellite: Astro_D
Newsgroups: sci.astro,sci.space

The original summary of Astro-D was roughly correct, but I can
add more detail and correct some errors.  The original launch
date of Feb. 5 has been postponed until Feb. 12 (pretty good
for the total slip over five years of development!).  There
will be substantial US participation in the mission and in
exchange the US community will have an opportunity to compete
for observing time.  NASA's Astrophysics Division will release
an NRA (NASA Research Announcement) on 15 Jan 93, due on 15 April,
to allow US scientists to propose to use 15% of the total observing
time for US only work and another 25% of the time for US-Japanese
collaborations.

The instruments consist of four conical foil X-ray telescopes
built by Pete Serlimitsos of Goddard Space Flight Center, two
X-ray CCD cameras built by George Ricker of MIT (with Penn State
Co-I's) and two gas scintillation proportional counters built
by Prof. Makashima of Tokyo University.  The four telescopes
are coaligned and will simultaneously point at the observing
target, allowing both CCD cameras and both GIS counters to
collect data.  Each mirror detector system has an effective
area around 400 cm^2, giving a total effective area greater
than Einstein, ROSAT or AXAF over most of the energy range.
Moreover the graze angle is smaller for these mirrors so they
retain large effective area up to 12 keV!  (For reference
the Einstein mirrors dropped off at 3-4 keV, ROSAT at 2 keV
and AXAF at 9 keV).

The major limitation of these mirrors is that they are not
true imagers (i.e. they are right cone segments and not para-
boloid-hyperboloid pairs).  This limits the spatial resolving
power to 1.3 arc min half power radius [although there is
a sharp core to the PSF which has been demonstrated to resolve
point source 36 arc sec apart.]  The spectral resolution
of the detectors is quite good.  The GIS has 8% energy resolution
at 5.9 keV, and CCDs have 120 eV resolution at 5.9 keV.  The
energy band pass runs from 0.4 keV up to 12 keV.

I don't know about press release material but an instrument
description will be included with the NRA in January.

John Nousek
Penn State University
Dept. of Astronomy and Astrophysics
[e-mail]

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

Date: Wed, 11 Nov 1992 21:29:55 GMT
From: Henry Spencer <[e-mail]>
Subject: Low-Pressure O2 Atmosphere
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Steve Linton) writes:
>... Later Appolo designs
>used 1atm of air on the pad, reducing to 0.2atm of O2 after launch.

Actually, the on-the-pad mix wasn't normal air, it was something like
40% nitrogen 60% oxygen.  It was the lowest nitrogen percentage they
could get away with and still keep flammability problems under control.
--
MS-DOS is the OS/360 of the 1980s.      | Henry Spencer @ U of Toronto Zoology
              -Hal W. Hardenbergh (1985)|  [e-mail]  utzoo!henry

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

Date: 11 Nov 92 20:19:00 GMT
From: "Craig L. Cole" <[e-mail]>
Subject: Lunar "colony" reality check
Newsgroups: sci.space,alt.sci.planetary

In article <[e-mail]>, [e-mail] writes...
>In article <[e-mail]>, [e-mail] (John D. Boggs) writes:
>=From article <[e-mail]>, by jenkins@fritz (Steve Jenkins):
>=>
>=> Oxygen, like many gases, has narcotic effects at very high pressures,
>=> such as in deep-sea diving.  It can cause blindness in newborns
>=>
>=
>=Yes to blindness in newborns, but it is the *nitrogen* that has the narcotic
>=effect in deep sea diving -- hence the use of helium for the really really
>=deep dives.
>
>If oxygen at high pressures DIDN'T cause the bad effects, why bother mixing it
>with helium?  Yes, nitrogen has narcotic effects at high pressure, but so does
>oxygen.

I'm no expert at deep sea diving or anything, but don't they use the helium
to increase to total atmospheric pressure in their submerisibles? So that
the pressure inside and outside the craft are more equal?

This is the opposite of space --  these guys are trying keep there craft
from imploding due to pressure. Increasing the pressure inside the craft
reduces the loads on the craft's strucutre.

On spacecraft, you want to keep pressure as low as possible to reduce
loads on the craft, since you have a vacuum outside.

Just a WAG. No encendiary requireded.

Craig Cole
[e-mail]
[e-mail]

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

Date: Wed, 11 Nov 1992 20:07:00 GMT
From: [e-mail]
Subject: Lunar "colony" reality check and Apollo fire
Newsgroups: sci.space,alt.sci.planetary

In article <[e-mail]>, [e-mail] (John P. Mechalas) writes...
>In article <[e-mail]> soc1070                          writes:
>>>   The fire ignited the velcro under high-pressure, and the resultant toxic
>>>fumes killed the astronauts within seconds.
>>
>>I beg to differ. It was in fact Apollo 1, as many have pointed out. If you
>>check your Apollo history, you will see that 8 circled the moon, 9 did
>>LEO tests, 10 tested the LM in lunar orbit, 11 landed, 12 landed next to
>>the Surveyor, 13 blew an oxygen tank on the way to the moon, etc.
>
>You are right, of course...  Rechecking my refs., I should have said
>"Spacecraft 12" and not "Apollo 12".  Damn naming conventions.  :)
>Apollo 1 was the mission number, and Spacecraft 12 was the spacecraft
>name...Pardon my confusion.
>
>>Secondly, the cause of the fire was never traced to any specific source.
>>According to Micheal Collens in _Carrying The Fire_, the inside of the
>>craft was so fried that a single cause could not be found; rather there
>>were several *probable* causes that resulted in an almost complete redesign
>>of the inside of the capsule.
>
>Correct.
>
>>You were right that almost anything will burn at 16psi pure O2, even
>>stainless steel. Unfortunatly for Grissom, White, and Chaffee, they didn't
>>die of toxic fumes. It was the fire that did them.
>
>I beg to differ on this point.  The burns weren't fatal.  The astronauts had
>suffocated.  The velcro and nylon netting in the spacecraft burned very *very*
>rapidly under 16psi of pure O2( later tests showed that the velcro burned at
>a rate of almost 3 inches per second), and filled the entire cabin with gas.
>The fire itself was very selective...a flight manual inside the craft (where
>White was located) was almost untouched.
>
>--
>John Mechalas                                          "I'm not an actor, but
>[e-mail]                                 I play one on TV."
>Aero Engineering, Purdue University                     #include disclaimer.h

I'll concede this one. Re-reading the section of _Carrying The Fire_,
the actual cause of death is not explectly stated. However, death by
burns is implied. The text makes it sound as though the entire inside
of the capsule was consumed by fire. Probably sells more books that way.

------
Tim Harincar                Millions long for immortality
Central Minnesota             who don't know what to do with
Association of Rocketry            themselves on a rainy Sunday
[e-mail]            afternoon. -Susan Ertz

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

Date: Thu, 12 Nov 1992 04:21:46 GMT
From: Ron Baalke <[e-mail]>
Subject: Mars Simulation in Antarctica
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Ron Baalke) writes...
>"Dante" to Descend into Volcanic "Inferno"
>
>    Later this season, NASA plans to send an eight-legged robot into the
>crater of Antarctica's Mount Erebus, the world's only easily-reached volcano
>with a permanent lava lake.  The rover, appropriately dubbed "Dante," will
>photograph the crater, measure the temperature of the lava lake and sample
>the gases it releases.
>
>    The Erebus project will test technology for future robotic explorers
>that could cross the rugged Martian landscape.  It also will collect science
>data to help understand Earth's environment, since some scientists think that
>gases from volcanic eruptions may play a role in depleting Earth's ozone layer.
>
>    Carnegie Mellon University, Pittsburgh, built Dante under a $2 million
>NASA grant.
>
>[NOTE:  This rover test has been postponed to next year.  Last week, Dante
>        damaged four its legs during a test run and has been sent back to
>        Carnegie Mellon for repairs.  Ron Baalke  ]
>

I've just been informed by someone associated with the Erebus project that
the repair work on Dante will only cause a 4 week delay.  So the rover
will be sent into Mount Erebus later this year.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Give people a second
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | chance, but not a third.
|_____|/  |_|/       |_____|/                     |

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

Date: Wed, 11 Nov 92 17:51:24 EST
From: John Roberts <[e-mail]>
Subject: newsgroups

-From: [e-mail] (David Knapp)
-Newsgroups: sci.space,alt.sci.planetary
-Subject: Edit your newsgroup header, please  was Re: Lunar "colony" reality check and Apollo fire
-Date: 11 Nov 92 05:46:46 GMT
-Organization: University of Colorado, Boulder

-There is no reason to have a thread going exactly and totally into two
-different newsgroups. If you see this happening, please edit your headers
-so we can limit the thread to one group or the other.

Keeping the non-planetary stuff out of alt.sci.planetary is good, but
please don't try to keep the planetary stuff out of sci.space/SPACE Digest.

Any progress on setting up a gateway?

John Roberts
[e-mail]

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

Date: Wed, 11 Nov 92 16:11:47 EST
From: John Roberts <[e-mail]>
Subject: Obscure Help Needed

[Posting this because the email address bounced - JR]

-From: [e-mail] (James Davis Nicoll)
-Newsgroups: sci.space
-Subject: Obscure Help  Needed
-Date: 11 Nov 92 01:36:58 GMT
-Organization: University of Western Ontario, London

-    An embarrassing request: my  HP died and I discover I cannot
-remember how to  do logs with a slide-rule,  nor  can I find my sr-related
-texts. Clearly, I am  senile. Anyone out  there recall how  the damn  things
-work?

-                            James Nicoll

Common (base 10) logs and antilogs are easy - just look at the C and L scales -
for instance, log(2) = ~.3. (I expect you know how to take it from there -
if not, reply.)

For natural logs, I would use the formula logn(x) = log(x) / log(e), where
e = 2.7182818... (thus avoiding those nasty e^x scales :-) .

Scientific calculators are so cheap (often available for less than $20 US),
that I like to keep several on-hand as backups. Unix systems also have
a pretty good calculator function (with an arbitrary number of memories,
which is convenient).

If you don't have a calculator with a graphical display, you should rush out
and buy one - they're great for single-point solutions of complex equations.

John Roberts
[e-mail]

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

Date: Wed, 11 Nov 1992 21:35:10 GMT
From: Henry Spencer <[e-mail]>
Subject: oxygen atmospheres
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Pat) writes:
>>...they switched to using a mixed-gas atmosphere before and
>>-during launch, with switchover to low-pressure pure oxygen on the way up.
>
>Why didn't the SHuttle do this?  i would have thought following apollo's
>lead, of  reducing cabin pressure and going to pure O2, you could
>reduce the difficulty of  EVA  which is a primary shuttle mission.

Actually, no, most shuttle missions do not do EVAs at all.  There are three
reasons for wanting to use Earth-normal air when you can:

1. There is some lingering suspicion of long-term adverse effects of
    low-pressure pure oxygen.

2. Biological experimenters don't want to have to use pressure chambers
    for their control specimens on Earth, and don't want to have to
    compensate for possible effects due to a different atmosphere.

3. It's very useful to be able to use air-cooled electronic equipment,
    and that requires something approaching normal air density.
--
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, 11 Nov 1992 21:27:59 GMT
From: Henry Spencer <[e-mail]>
Subject: Space suit research???
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (STANCZYK MICHAEL B) writes:
>With all the talk about US space suits being at 5 psi and pure O2 I was
>wondering what the current state of research is in space suits using
>1 atm and normal air?

Advanced spacesuit research is basically stalled for lack of funding.
A high-pressure suit (probably 8psi or so rather than full normal
pressure -- most people can take a certain amount of pressure change
without much risk of the bends) was planned for the space station but
scuttled by funding cuts.  It would still be useful, because prebreathing
greatly increases the time needed for a spacewalk.
--
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, 11 Nov 1992 20:48:57 GMT
From: John Harper <[e-mail]>
Subject: Swift-Tuttle Comet a threat to earth?
Newsgroups: sci.astro,sci.space

In article <[e-mail]> [e-mail] (Dave Jones) writes:
>Not quite.  Pangaea was the original supercontinent.  It split into
>Laurasia (the Canadian Laurentian Shield and East Asia together) and
>Gondwanaland (just about everything else).

Not quite. Pangaea had a temporary existence, roughly Permian to Jurassic.
Both before and after there were varying numbers of distinct continents.
Besides the places listed above Laurasia also contained most of USA, Mexico,
Europe (not Italy, Greece), W Asia (not Turkey, Arabia, Iran). Argument still
goes on so far as I know about which parts of Indonesia and China were Laurasia
and which were Gondwana, about when Gondwana was assembled, and about when
and whence various parts of Canada+USA in and W of the Rockies moved north
into their present positions relative to the rest of USA+Canada.

John Harper Mathematics Dept. Victoria University Wellington New Zealand

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

Date: Wed, 11 Nov 92 17:33:29 EST
From: John Roberts <[e-mail]>
Subject: Thumbs up

-From: [e-mail] (Bruce Watson)
-Subject: Lunar astronaut covers earth with thumb
-Date: 10 Nov 92 20:21:35 GMT
-Organization: Alpha Science Computer Network, Denver, Co.

-On the last installment of "Space Age" Jim Lovell said while he
-was in the vicinity of the moon, he could cover the earth with his
-thumb while his arm was outstretched. (It was also attributed to
-Rusty Schweikart).

-I heard this a few years ago on a radio talk show with one of
-the lunar astronauts as guest--was it Jim Lovell?

Yes.

-A caller, who had a German accent, had trouble with this reasoned:

-(1) This distance to the moon from the earth is the same as the
-    as the distance to the earth from the moon,
-(2) The earth is larger than the moon, and
-(3) We ordinary mortals here on earth can't cover the moon with
-    a thumb with arm outstretched.

-His unstated conclusion was that the astronaut could not have done
-it and you could sense his reluctance to call the astronaut a liar.

-What is the error the caller made? Give up? It's number (3).
-There's a full moon out tonight. Go out and try it.

Either he didn't try it, or he forgot to close one eye. :-)

I was a little worried about that statement when I heard it on the show,
especially since the context implied that he tried it only shortly after
the burn to leave LEO and head toward the moon. Here's a transcription
from the show:

"I can recall vividly how quickly the Earth began to shrink. It got to be
quite small right away. Really, it was sort of an unusual feeling.
You could actually put your thumb up to the window, and hide the Earth
behind your thumb."

(The accompanying video shows the astronauts bare-handed.) Even at the
distance of the moon, covering the Earth with your thumb at arm's length
would be very marginal, unless you have unusually large thumbs (Lovell
doesn't).

I finally decided that he hadn't necessarily had his arm fully extended.
(Remember, the Apollo capsule was very cramped.) Lovell didn't say anything
on the show about having his arm fully extended, and in fact on the show
he held his thumb up only a little more than a foot in front of his face.

John Roberts
[e-mail]

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

Date: Wed, 11 Nov 92 16:58:02 EST
From: John Roberts <[e-mail]>
Subject: What kind of computers are in the shuttle?

-From: [e-mail] (I am a terminator.)
-Subject: What kind of computers are in the shuttle?
-Date: 11 Nov 92 17:53:36 GMT
-Organization: University of Saskatchewan, Saskatoon, Canada

-The computers used to control the shuttle use very complex programs
-that people don't want to rewrite for newer computers. Has any
-upgrades been done or are the computers still the same old beasts?

Most or all of the orbiters now have the new computers, which are much more
powerful (and have more memory) than the old computers. I believe they're
software-compatible. (I *don't* know whether any new functions were added,
or whether the software has been changed (other than lookup tables, etc.).
The Shuttle control software is claimed to be the most nearly error-free
complex code ever created - millions of dollars went into assuring that.)

I believe one problem with the old computers (and I only saw it once, some
time ago, so don't take it as established fact) was that they did not have
sufficient storage to hold all the abort contingencies. You can imagine the
displeasure of a Shuttle commander rummaging around for the Once-Around-Abort
tape and trying to get it loaded before the first action is required. :-)

Hm, when in doubt, cheat and look up the original references. Here's a
description of computer and computer-related changes from the STS-49 Press
Kit (the first launch of Endeavour):

.............

>From: [e-mail] (Peter E. Yee)
Subject: STS-49 Press Kit (Forwarded)
Date: Sat, 18 Apr 1992 19:56:05 GMT

               STS-49 PRESS KIT
                    MAY 1992

...
IMPROVED FEATURES OF SPACE SHUTTLE ENDEAVOUR

    Many systems onboard Endeavour have had design changes or have
been updated from earlier equipment to take advantage of technological
advances and continue improvements to the Space Shuttle.  The upgrades
include several improved or redesigned avionics systems; installation
of a drag chute as part of a series of landing aid additions to the
orbiters; and modifications to pave the way for possibly extending
Shuttle flights to last as long as 3 weeks in the future.

    Some such updated systems already have been installed in the
rest of the shuttle orbiters as well as Endeavour; some will be
installed in all orbiters in the near future; and others will be used
on Endeavour only...

    The advanced general purpose computers (GPCs) are now in the
process of being incorporated into the entire orbiter fleet and will be
installed and used on Endeavour for its first space flight.  The
updated computers have more than twice the memory and three times the
processing speed of their predecessors.  Officially designated the IBM
10-101S, built by IBM, Inc., they are half the size, about half the
weight and require less electricity than the first-generation GPCs.
The central processor unit and input/output processor, previously
installed as two separate boxes, are now a single unit.

    The new GPCs use the existing Shuttle software with only subtle
changes.  However, the increases in memory and processing speed allow
for future innovations in the Shuttle's data processing system.
Although there is no real difference in the way the crew will operate
with the new computers, the upgrade increases the reliability and
efficiency in commanding the Shuttle systems.  The predicted Rmean time
between failuresS (MTBF) for the advanced GPCs is 6,000 hours.  The
flight computers are already exceeding that prediction with an MTBF of
18,500 hours.  The MTBF for the original GPCs is 5,200 hours.

New GPC Specifications
Dimensions:         19.52S x 7.62S x 10.2S
[I wonder what an "S" is? From context, I'd guess "inches". - JR]
Weight:         64 lbs.
Memory Capacity:     262,000 words (32-bits each)
Processing Rate:     1.2 million instructions per second
Power Requirements:      550 watts

HAINS Inertial Measurement Units

    The High Accuracy Inertial Navigation System (HAINS) Inertial
Measurement Unit (IMU) will be incorporated into the orbiter fleet on
an attrition basis as replacements for the current KT-70 model IMUs.
The three IMUs on each Shuttle orbiter are four-gimbal, inertially
stabilized, all-attitude platforms that measure changes in the
spacecraft's speed used for navigation and provide spacecraft attitude
information on flight control.
    For Endeavour's first flight, one HAINS IMU will fly with two
accompanying DT-70 IMUs to provide redundancy with proven hardware.
The HAINS IMU for the Space Shuttle is a derivative of IMUs used in the
Air Force's B-1B aircraft.  It includes an improved gyroscope model and
microprocessor and has demonstrated in testing improved abilities to
hold an accurate alignment for longer periods of time.  In addition, it
has proven more reliable than the KT-70 IMUs.  The new IMUs require no
software changes on the orbiter or changes in electrical or cooling
connections.  The HAINS IMU is manufactured by Kearfott, Inc., of
Little Falls, N.J.

Improved Tactical Air Navigation Systems

    A complete set of three improved TACANS will fly on Endeavour's
first flight.  The improved TACAN is a modified off-the-shelf unit
developed by Collins, Inc., of Cedar Rapids, Iowa, for military
aircraft and slightly modified for the Shuttle.  The improved TACAN
operates on 28-volt direct current electricity as compared to the
current TACANs that use 110-volt alternating current for power.  Also,
the new TACANs do not require forced air cooling as do the current
TACANs.
    The TACANs' connections to the Shuttle's guidance, navigation
and control system are identical.  The TACANs provide supplemental
navigational information on slant range and bearing to the orbiter
using radio transmissions from ground stations during the final phases
of entry and landing.

Enhanced Master Events Controller (EMEC)

    The EMEC features improved reliability, lower power usage and
less maintenance than current MECs.  The new design uses 30 percent
less electricity and has more internal backup components.  The MECs,
two aboard each Shuttle, are a relay for onboard flight computers used
to send signals to arm and fire pyrotechnics that separate the solid
rockets and external tank during assent.  The EMEC were built by
Rockwell's Satellite Space Electronics Division, Anaheim, Calif.
Present plans call for Endeavour to be the only orbiter with the
EMECs.

Mass Memory Unit Product Improvement

    Improvements to the current MMUs in the form of modifications
include error correction and detection circuitry to accommodate tape
wear, tape drive motor speed reduction to extend the tape's lifetime.
In addition, modifications were made to the tape drive head to extend
its lifetime.  The improvements have no effect on the current software
or connections of the MMUs.  Two MMUs are on each orbiter and are a
magnetic reel-to-reel tape storage device for the Shuttle's onboard
computer software.  The modification to the MMUs will be done for the
first flight of Endeavour and for the rest of the orbiter fleet during
normal maintenance activities.  The MMUs were built and upgraded by
Odetics of Anaheim, Calif.

Enhanced Multiplexer-Demultiplexer

    The EMDM uses state-of-the-art components to replace obsolete
parts and improve maintenance requirements.  The new components have
simplified the structure of the EMDM by more than 50 parts in some
instances.  The EMDMs are installed on Endeavour, but plans have not
been made to replace the current MDMs in other orbiter.  The MDMs, 19
located throughout each orbiter, act as a relay for the onboard
computer system as it attains data from the Shuttle's equipment and
relays commands to the various controls and systems.  The EMDMs are
manufactured by Honeywell Space Systems Group, Phoenix, Ariz.

Radar Altimeter

    The improved radar altimeter aboard Endeavour already has been
installed and flown on all other Shuttle orbiters since STS-26.  The
altimeter is an off-the-shelf model originally developed for the
military's cruise missile program.  The altimeter has the capability to
automatically adjust its gain control as a function of changes in
altitude.  Along with anti-false lock circuitry, the improvements have
eliminated a problem frequently experienced with the original radar
altimeter caused by interference from the Shuttle's nose landing gear.
The radar altimeter is built by Honeywell, Minneapolis.

Improved Nosewheel Steering

    Improvements to the nosewheel steering mechanisms include a
second command channel, used as a backup in case of a failure in the
primary channel, for controlling the steering through the onboard
computers.  In addition, a valve has been installed in the hydraulic
system to switch in a secondary hydraulic pressure system in case of a
failure in the primary system.  Endeavour will have the modifications
prior to its first flight, and the rest of the orbiter fleet will have
the improvements made during their major modifications periods.  The
improved nosewheel steering was designed by Sterer Engineering and
Manufacturing Components, Los Angeles.

Solid State Star Tracker

    The SSST is a new star tracker design developed for Endeavour
which takes advantage of advances in star tracker technology.  The two
star trackers on each Shuttle orbiter are used to search for, detect
and track selected guide stars to precisely determine the orientation
of the spacecraft.  The precise information is used to periodically
update the orbiter's IMUs during flight.  The SSST uses a solid state
charge coupled device to convert light from stars into an electric
current from which the star's position and intensity are determined.
The solid state design consumes less electricity and provides greater
reliability than the current star trackers.  The SSSTs require no
modification to the orbiter or its software for installation.  Current
plans are for one SSST to be installed on Endeavour and another to be
incorporated into the orbiter fleet on an attrition basis.  The SSST
was developed and built by Ball Aerospace Division, Boulder, Colo.

.............
John Roberts
[e-mail]

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

Newsgroups: sci.space,alt.sci.planetary

From: Dave Jones <[e-mail]>
Subject: Re: Lunar "colony" reality check
Message-Id: <[e-mail]>
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Carl J Lydick ([e-mail]) wrote:
> In article <[e-mail]>, [e-mail] (John D. Boggs) writes:
> =From article <[e-mail]>, by jenkins@fritz (Steve Jenkins):
> =>
> => Oxygen, like many gases, has narcotic effects at very high pressures,
> => such as in deep-sea diving.  It can cause blindness in newborns
> =>
> =
> =Yes to blindness in newborns, but it is the *nitrogen* that has the narcotic
> =effect in deep sea diving -- hence the use of helium for the really really
> =deep dives.
>
> If oxygen at high pressures DIDN'T cause the bad effects, why bother mixing it
> with helium?  Yes, nitrogen has narcotic effects at high pressure, but so does
> oxygen.

Oxygen at, say, 5 atm. pressure strikes me as a very unhealthy gas to
breathe.  Even a few atm., as we might have used in a bomb calorimeter,
will consume anything combustible (lung linings etc.) with the slightest
encouragement.  If you're going to breathe high pressure gas for deep
diving purposes, you need an inert filler to add to the standard partial
pressure of oxygen.

--
||------------------------------------------------------------------------
||Dave Jones ([e-mail])|Eastman Kodak Co. Rochester, NY  |

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End of Space Digest Volume 15 : Issue 413
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