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Date: Thu, 11 Oct 1990 03:47:40 -0400 (EDT)
Subject: SPACE Digest V12 #446

SPACE Digest                                     Volume 12 : Issue 446

Today's Topics:
              Re: gravity and atmosphere
             Pioneer 11 Update - 10/10/90
              Re: Iron asteroid in orbit
              Re: Iron asteroid in orbit
            Microgravity Data Bank (MGDB)
         NASA Headline News for 10/10/90 (Forwarded)
             News From OSCAR-11  30Sep90

Administrivia:

    Submissions to the SPACE Digest/sci.space should be mailed to
  [e-mail].  Other mail, esp. [un]subscription notices,
  should be sent to [e-mail], or, if urgent, to
             [e-mail]

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

Date: 5 Oct 90 15:48:13 GMT
From: news-server.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: gravity and atmosphere

In article <[e-mail]> [e-mail] (james d. Del Vecchio) writes:
>How much gravity would a planet need to have to keep enough oxygen
>to equal 1/5 of a sea level atmosphere?  How much to hold enough
>nitrogen to equal 78% of a sea level atmsphere?

I don't have exact numbers on hand, but the amounts are almost irrelevant.
(Venus has kept many times Earth's atmosphere despite being slightly
smaller.)  The key question is whether it has enough gravity to hang
onto oxygen or nitrogen at all, over geological time.  If it does, it
will have whatever amount was present in the first place and didn't get
eaten up by reactions with the crust or other loss mechanisms.

>What other factors are involved besides gravity?

Temperature.  The key question is whether more than a vanishingly small
fraction of the relevant molecules are moving faster than escape velocity.
Molecular velocities are lower at lower temperatures.  Also molecular
weight, because heavier molecules are slower.

For complex molecules like water, there are also loss mechanisms like the
one that operated on Venus:  ultraviolet radiation breaking off a hydrogen
atom, which escapes at high velocity.  (This doesn't happen significantly
on Earth because Earth's water condensed into oceans and, partly as a
result, our upper atmosphere is very dry and there is little water exposed
to the shortwave UV.)

>What gasses other than nitrogen could
>be used to "cut" a planet's oxygen without danger to people?

It depends on whether you are thinking about natural gases or artificial
ones.  Whatever it is has to be fairly inert chemically and very inert
biologically, and the list of natural candidates that are likely to occur
in quantity is quite short.  Actually, the list of possible artifical
candidates is also pretty short, and we don't know very much about
long-term biological effects of most of them.

For that matter, we don't know for sure that long-term absence of major
quantities of nitrogen doesn't have some obscure harmful effect.

Neon or argon should work.  The heavier inert gases won't; they are too
rare and they also tend to have biological effects (xenon in quantity is
a good anesthetic, and would be used for that if it weren't so expensive).
Helium ought to work but it will escape quickly.  All the inert gases
suffer from being relatively rare elements (except helium, but it too is
rare on Earth-size planets).  I cannot immediately think of any candidate
except possibly some of the chloro/fluorocarbons (!), which rely on the
not-too-common halogens.

If you want things that are likely to be found in bulk, I think nitrogen
really is it.  The only real question is how much of it you need.  Apart
from possible subtle biological effects, and the speculation that cutting
the oxygen with an inert gas damps fires somewhat, there is no obvious
reason why you *have* to have it.  Neither human respiration nor fires
will be a major problem if you keep the oxygen down to the same partial
pressure it is here, circa 3psi.  (15psi of oxygen, on the other hand,
is quite dangerous in terms of fire and is not considered entirely safe
for prolonged breathing.)  However, the biological effects of prolonged
low pressure are poorly known -- Earth experience doesn't get down that
far because people run out of oxygen first -- and there are other
annoying problems like poorer cooling of air-cooled electronics.
--
Imagine life with OS/360 the standard  | Henry Spencer at U of Toronto Zoology
operating system.  Now think about X.  |  [e-mail]   utzoo!henry

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

Date: 10 Oct 90 15:09:16 GMT
From: sdd.hp.com!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Pioneer 11 Update - 10/10/90


                            Pioneer 11 Update
                            October 10, 1990

     Pioneer 11 spacecraft problems continue.  Following the high power
uplink support with the 70 meter antenna in Australia which had receiver
in-lock only every 14 to 20 seconds, the Goldstone 70 meter station was
not able to acquire a good 3-way downlink, except for about 8 seconds in
which 2 frames of telemetry were sent to the project.  Efforts to get a
good downlink continues.
      ___    _____     ___
     /_ /|  /____/ \  /_ /|
     | | | |  __ \ /| | | |      Ron Baalke         | [e-mail]
  ___| | | | |__) |/  | | |___   Jet Propulsion Lab | [e-mail]
 /___| | | |  ___/    | |/__ /|  M/S 301-355        |
 |_____|/  |_|/       |_____|/   Pasadena, CA 91109 |

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

Date: 10 Oct 90 02:05:34 GMT
From: visix![e-mail]  (Amanda Walker)
Subject: Re: Iron asteroid in orbit

In article <[e-mail]>,
[e-mail] (John Roberts) writes:

> guided right into the bore of your electromagnetic launcher! At this point
> it is a simple matter to operate the launcher backwards, to decellerate the
> payload. You might even be able to recover some energy from the operation.

A mass driver with regenerative braking?  Yowza...  somehow I that
that "a simple matter" underestimates it a bit, though... what about
plain old thermal energy from re-entry?  Bleeding that off usefully
(not to mention safely) could be a tad tricky.

--
Amanda Walker                              [e-mail]
Visix Software Inc.                    ...!uunet!visix!amanda

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

Date: 10 Oct 90 20:30:23 GMT
From: timbuk!sequoia![e-mail]  (Greg Titus)
Subject: Re: Iron asteroid in orbit

In article <[e-mail]> [e-mail] (Amanda Walker) writes:
>In article <[e-mail]>,
>[e-mail] (John Roberts) writes:
>
>> guided right into the bore of your electromagnetic launcher! At this point
>> it is a simple matter to operate the launcher backwards, to decellerate the
>> payload. You might even be able to recover some energy from the operation.
>
>A mass driver with regenerative braking?  Yowza...  somehow I that
>that "a simple matter" underestimates it a bit, though... what about
>plain old thermal energy from re-entry?  Bleeding that off usefully
>(not to mention safely) could be a tad tricky.
>

No problem!  At the back end of the launcher, at which point the
payload will be nicely slowed down, you put a giant tub of water.  A
very heavy lid is hinged to one side of the tub (away from the
launcher), and the other side, toward the launcher, is held up by a
(very strong) stick.

As the payload exits the launcher, traveling quite slowly now but
having been exceedingly heated up in the reentry and capture process,
it strikes the stick and then falls in the water.  With the stick
knocked out of the way, the lid slams shut.  The hot payload boils the
water, cooling itself and creating copious steam.  The steam is
captured and used to drive a small turbine, which in turn charges a
bank of batteries.

When the payload has cooled sufficiently, a robotic arm inside reopens
the lid.  Another robotic arm picks up the payload and puts it on the
conveyor belt next to the tub, then puts the stick back in place.  The
first arm then gently rests the lid on the stick.

The cycle is now complete, and the apparatus is ready for the next
"catch".

All power for these operations is provided by the battery bank.  Any
excess power generated would of course be sold to the local utility.

greg
--
--------------------------------------------------------------
Greg Titus ([e-mail])             Compiler Group (Ada)
Cray Research, Inc.                               Santa Fe, NM
Opinions expressed herein (such as they are) are purely my own.

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

Date: 11 Oct 90 00:44:10 GMT
From: sam.cs.cmu.edu![e-mail]  (Vincent Cate)
Subject: Microgravity Data Bank (MGDB)


Does anyone know anything about the "Microgravity Data Bank"?

There was an article about it in Space Technology vol. 9
no. 3, 1989 but our library does not seem to a copy.

It is supposed to be an easily accessible database with
extensive information on microgravity experiments.  This
"easily accessible" part makes me hope that it is somewhere
on the net.

Anybody have any info?

Thanks,

    -- Vince

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

Date: 11 Oct 90 02:47:53 GMT
From: trident.arc.nasa.gov![e-mail]  (Peter E. Yee)
Subject: NASA Headline News for 10/10/90 (Forwarded)


              Headline News
Internal Communications Branch (POC) NASA HQ


Wednesday, October 10, 1990    Audio Service: 202/755-1788


This is NASA Headline News for Wednesday, October 10, 1990

Following a nearly flawless 5-day mission, the crew of STS-41
returned Discovery to Earth this morning at 9:58.  The
landing, at California's Edwards Air Force Base, was on Runway
22, the concrete main runway.  The concrete runway was
selected to allow tests of Discovery's new main gear carbon
brakes and nose wheel steering during the landing.

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

Columbia was rolled back to the Vehicle Assembly
Building at the Kennedy Space Center yesterday as a
precaution, due to tropical storms in the Florida vicinity.
Tropical Storm Klaus, the most threatening of the storms,
however, has dissipated following landfall in the Bahamas.
Winds were described as quite strong at the pad area yesterday.
Columbia is expected to be rolled back to Pad B sometime
Monday, Oct. 15.

Following the roll back, technicians reestablished ground
support power to the Astro-1 payload.  Routine monitoring
is scheduled for the remainder of this week.  The Broad Band X-
ray Telescope is set to be serviced again with liquid argon on
Monday.  All indications give the payload a clean bill of health.

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

Atlantis is now scheduled to be rolled out to launch pad 39-
A late tomorrow evening.  The schedule for a tanking test of
Atlantis' fuel system is still being developed.


The Hubble Space Telescope was just west of Equatorial Africa
at the time of Discovery's landing at Edwards Air Force Base
this morning at 9:58 am EDT.


Here's the broadcast schedule for Public Affairs events on NASA
Select TV.  All times are Eastern.  **indicates a live program.

Wednesday, 10/10/90
    11:30 am    **Post-landing briefing from DFRF.
    1:15 pm    **Magellan at Venus status briefing from JPL.

Thursday, 10/11/90
    11:30 am    NASA Update will be transmitted.



All events and times may change without notice.  This report is
filed daily, Monday through Friday, at 12:00 pm, EDT.  It is a
service of Internal Communications Branch at NASA
Headquarters.  Contact:  CREDMOND on NASAmail or at
202/453-8425.


NASA Select TV:  Satcom F2R, Transponder 13, C-Band, 72
degrees West Longitude, Audio 6.8, Frequency 3960 MHz.

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

Date: 2 Oct 90 15:21:10 GMT
From: ka2qhd![e-mail]  (John Magliacane)
Subject: News From OSCAR-11  30Sep90






* UOSAT-2 OBC STATUS INFORMATION *

DIARY OPERATING SYSTEM V3.1 SMH MLJM MSH

 Today's date is 2 /10 /90  (Tuesday)
 Time is 13 :48 :48 UTC
 Auto Mode is selected
 Spin Period is - 269
 Z Mag firings  = 0
 + SPIN firings = 33
 - SPIN firings = 20
 SEU count      = 23953
 RAM WASH pointer at A057
 WOD commenced 2 /10 /94 at 0:0 :9
 with channels 53 ,
 Last cmnd was 109 to 0 , 0
 Attitude control initiated, mode 1
 Data collection in progress


           **** UoSAT-OSCAR-11 BULLETIN     30 September 1990 ****

                         UoSAT MISSION CONTROL CENTRE
         University of Surrey, Guildford, Surrey, GU2 5XH, England




** UO-11

Suggestions on the most useful operating schedule for UoSAT-2 should be sent
to UoSAT as soon as possible so that they can be taken into account during an
operations review due to take place later this month.


** FO-20

FO-20 is continuing to experience high temperature problems (due to the
spacecraft experiencing no eclipse periods during which it can cool down)
which is forcing a drastic reduction of operations.  As of the weekend of 29
Sept 90, the battery temperature had risen to near 45 degrees C.  Extended
exposure to high battery temperature will decrease the useful life of the
battery.

From           To              Mode
011090  0900   021090   0910   PSK Telemetry acquisition
041090  0955   041090   2330   JA
081090  0920   081090   1110   JA and JD
111090  0825   121090   0850   JD

The above dates and time are in UTC and the schedule may change without
notice.  The FO-20 Command Team will be monitoring satellite performance and
operations during these times and may turn off the transponder if they
determine that the satellite is in danger.

** MIR

A new and exciting amateur radio project is being planned for the Mir space
station known as the "Amateur Radio Experiment on Mir" or AREM.  This project
is the result of a collaboration between the Soviet Union and the Austrian
Amateur Radio Society (OeVSV).  It is designed to provide equipment for both
2M packet data and voice transmissions from Mir.  The voice messages will be
spoken in German, Russian, and English and will alternate with packet
transmissions.  The first AREM operations are expected to begin around January
1991 when an Austrian cosmonaut will install the station after he joins the
crew of the Mir.  To obtain further information about AREM, please write to:

Wolf Hoeller (OE7FTJ)
Amraserstrasse 19
A-6020 Innsbruck
Austria

** AO-13

The present transponder schedule for AO-13 is as follows:

Mode-B          : MA 003 to MA 165
Mode-JL         : MA 165 to MA 195
Mode-B          : MA 195 to MA 240
Off             : MA 240 to MA 003  (Mode B Beacon On)
Omni Antennas   : MA 240 to MA 060

The September 10 attitude estimate is:

BLON = 205  and  BLAT = -7

** AO-10

Until further notice please DO NOT use AO-10's transponder.


** BADR-1

Would any stations receiving signals from the BADR-1 spacecraft on 145.825 MHz
and 144.010 MHz please send brief details to UoSAT - thank you.

Thanks to AMSAT-NA ANS and its contributors for much of the above information,
there is generally insufficient 'room' in the UO-11 Bulletin to give regular
acknowledgements.


** $BID **

Please use BID $UOSAT.930 for PR BBS use.




--
John A. Magliacane                 FAX  : [phone]
Electronics Technology Department  AMPR : KD2BD @ NN2Z.NJ.USA.NA
Brookdale Community College        UUCP : ..!uunet!masscomp!ocpt!ka2qhd!kd2bd
Lincroft, NJ  07738  USA           VOICE: [phone] ext 607

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

End of SPACE Digest V12 #446
*******************