Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/spacedig/v09_4/v9_451.txt

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Subject: SPACE Digest V9 #451

SPACE Digest                                      Volume 9 : Issue 451

Today's Topics:
         Re: Long Duration Exposure Facility
         Re: Long Duration Exposure Facility
           Magellan Status for 05/19/89 (Forwarded)
                  nasa sites
              Re: Alien viruses
         Re: Sun's invisible partner NEMESIS
            New space shuttle name
             Re: The late NEMESIS Theory
         Re: Magellan Status for 05/19/89 (Forwarded)
            Re: New Orbiter Name Announced
         Re: Sun's invisible partner NEMESIS
              Re: Magellan & SRB exhaust
            Magellan Advisory (Forwarded)
----------------------------------------------------------------------

Date: 19 May 89 15:04:05 GMT
From: mailrus!jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Kieran A. Carroll)
Subject: Re: Long Duration Exposure Facility

[e-mail] (Lee Brotzman) writes:
>mnetor!utzoo![e-mail]  (Henry Spencer) writes:
>>...NASA is terrified of the public-relations impact of another Skylab,
>>and considers it quite urgent that LDEF not be allowed to reenter.
>
>If NASA is so "terrified" of allowing a light-weight, sure-to-burn, satellite
>like LDEF to reenter, then why is the Solar Maximum Mission (SMM) being allowed
>to reenter?  Although public relations may be part of it, I think that the
>main reason to get LDEF is simply that it is useful to do so.  The materials
>that were placed on it are pretty much useless now since they have had a
>*really* long exposure (maybe not).  That doesn't mean the thing shouldn't be
>brought back, looked over and possibly loaded up and re-launched.
>

According to one of the recent issues of AWST, the SDI Organization is
keen on seeing LDEF retrieved. While most of the experiments (including
one from here at the U of T) were designed for a one-year mission,
and so will likely return poor results after an additional four years
in space, the SDIO is interested in the effects of the space environment
on the spacecraft's >>bus<<. SDI would result in a large number of
satellites being orbited, and left dormant for years at a time; they are
interested in finding out how typical satellite components stand up to
years of time in space. Also, they apparently plan to do tests on
some LDEF components, to determine how well they would stand up to
attack after being in space for a long time (ie. does the hardness
of a laser battle station deteriorate with time?).

A chilling note: the article states that, due to recent unexpectedly-
high levels of solar activity, LDEF's projected re-entry time is now
sooner than it was -- sometime in December 1989. The SDIO wants NASA
to mount a mission prior to December to do the retrieval; administrator Truly
says that it likely won't fly until mid-december, but that that's all right,
because the re-entry probably won't occur until >late< December.
The sticking point in the negotiations is that NASA only wants to
fly one mission between Galileo and Ulysses (I think that's the pair
they mentioned); the one flight is a DoD payload that's been delayed for quite
awhile now. To retrieve LDEF before re-entry, it looks like DoD will
have their payload bumped again (by NASA and SDIO), or else NASA will have
to fly a mission that they don't think  they have time to prepare for
(shades of early 1986).
--

     Kieran A. Carroll @ U of Toronto Aerospace Institute
     uunet!attcan!utzoo!kcarroll [e-mail]

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

Date: 19 May 89 15:48:35 GMT
From: mailrus!jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Long Duration Exposure Facility

In article <Added.sYQqu3W00Ui30ItE8=@andrew.cmu.edu> [e-mail] (Lee Brotzman) writes:
>>... NASA is terrified of the public-relations impact of another Skylab,
>>and considers it quite urgent that LDEF not be allowed to reenter.
>
>If NASA is so "terrified" of allowing a light-weight, sure-to-burn, satellite
>like LDEF to reenter, then why is the Solar Maximum Mission (SMM) being allowed
>to reenter? ...

Because Solar Max is much smaller.  It's "just another satellite"; they
reenter all the time.  LDEF is one of the biggest things launched since
Skylab.  Remember, we are talking about public perceptions, and fears
thereof, not actual dangers.
--
Subversion, n:  a superset     |     Henry Spencer at U of Toronto Zoology
of a subset.    --J.J. Horning | uunet!attcan!utzoo!henry [e-mail]

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

Date: 19 May 89 18:33:11 GMT
From: trident.arc.nasa.gov![e-mail]  (Peter E. Yee)
Subject: Magellan Status for 05/19/89 (Forwarded)


            MAGELLAN STATUS
            May 19, 1989


    Daily momentum wheel desaturations continue as scheduled, twice
daily, 00:45 a.m. and 12:45 p.m. PDT, project said today.  The daily
star calibration also was performed without difficulty.  Both stars
were detected and a full attitude update was obtained.

    The temperatures of Rocket Engine Modules 3 and 4 continue to
slowly cool as the celestial geometry gradually changes. They are
running a steady 56-58 C (132.8-136.4 F) except during wheel
desaturations when they warm up into the 60s C (140-156 F), still
considerably below the design limit of 83 C (181.4 F).

    The Command Data System breadboard began working again in the
System Verification Lab and the test of Cruise)2 computer command
sequence, which holds the upcoming Trajectory Correction Maneuver, is
going well and nearing completion. Project will be prepared to upload
the sequence Saturday.

    A meeting today was scheduled to address solution options to
the three current problems: 1) Rocket Engine Module temperatures; 2)
star rejects during star calibrations; and 3) desaturation frequency.






    SPACECRAFT Distance  From Earth (mi)
    2,220,474

    Velocity  Geocentric                         5,905 mph
          Heliocentric                      59,970 mph

    Round Trip Light Time                           12.2 sec

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

Date: 19 May 89 23:26:59 GMT
From: asuvax!enuxha![e-mail]  (Norman C. Kluksdahl)
Subject: nasa sites

(Apologies for the use of the bandwidth--once again, the infamous
 evil e-mail system prevents direct response)

Joni Guldenpfennig,
I got your note, and tried to forward the info four different paths.
None of them worked.  Sorry.  Can you get me a better path?

N. Kluksdahl                          [e-mail]

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

Date: Fri, 19 May 89 11:03:53 EDT
From: John Roberts <[e-mail]>
Disclaimer: Opinions expressed are those of the sender
    and do not reflect NIST policy or agreement.
Subject: Re: Alien viruses

>From: Robert Nelson <[e-mail]>
>I noticed that someone commented on waht would happen if we had contact
>with ETs, and if we could get a virus from them or perhaps something
>from -us- could affect them.  I turn your interest to the book/movie
>_The_Andromeda_Strain_.  It depicts a scenerio that has a meteor landing
>and there is a virus of sorts on it, actually I think that it is some
>form of bacteria, which breaks down carbon compounds like plastics...
>any comments?

I don't think Crichton's story matches any plausible real-life scenario. In
the book/movie, an alien microorganism finds its way to Earth, and begins to
enthusiastically wipe out 99+% of the population in affected areas. Suddenly,
every one of the teeming trillions of organisms just happens to mutate into
harmless form (!) Another writer in this class is D.F. Jones (the Colossus
series), who has written novels filled with numbers that are off by dozens
of orders of magnitude.

Some science fiction writers *are* very careful with numbers (though they
can still mess up on the sociology, etc.) Robert Heinlein reported that in
the process of writing a novel, he had spent several days working on a set
of calculations, just so a single paragraph describing orbital maneuvers
would be accurate.
                               John Roberts
                               [e-mail]

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

Date: 19 May 89 10:56:37 GMT
From: bunny![e-mail]  (Rod Stephens)
Subject: Re: Sun's invisible partner NEMESIS


Read the book "NEMESIS". It's quite readable. As I read it the theory
is not dead. The author predicts that Nemesis (if it exists) would be
some sort of red dwarf (I think) that would be visible from the earth
but would be hard to tell apart from a bigger more distant star. He
implies there is some hope of locating it soon since imaging systems
are just about sensitive to record and analyze stuff of this brightness
now.

        Rod Stephens
        GTE Laboratories

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

Date: Fri, 19 May 89 12:04:48 PDT
From: Peter Scott <[e-mail]>
Subject: New space shuttle name

ginosko!infinet!ulowell!hawk![e-mail]  (Roger Levasseur) writes:

>Captain James Cook who explored the Pacific Ocean in the late 1770's,
>and charted Alaska and Hawaii sailed in ships named HMS Resolution
>and HMS Endeavour.  If the shuttle is named after it, it would certainly
>be silly to use another spelling.

If they named if after this particular ship, agreed.  AW&ST uses the name
"Endeavor" several times in the current issue with no allusion to any
alternate spelling, however, so it'll be interesting to see what actually
winds up on the side.

Peter Scott ([e-mail])

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

Date: 19 May 89 14:19:44 GMT
From: sun-barr!cs.utexas.edu!ut-emx![e-mail]  (Ethan Tecumseh Vishniac)
Subject: Re: The late NEMESIS Theory

In article <[e-mail]>, [e-mail] (Bill Wyatt) writes:
>
> Several things would have to be verified for the entire NEMESIS theory
> to be accepted. A short list, off the top of my head:
>
> ...list mostly deleted ..
> 5) The iridium layer(s) must be of extraterrestrial origin.

The original claim was that the K-T boundary had to be.  One
comment that I see periodically is that the same irridium anomaly
that shows up in meteorite abundances is also present (perhaps to
a lesser degree) in the mantle.  It follows that extensive volcanism
*might* have a similar effect.  Any geologists following this?

> 6) There must be an Ir or other tracer layer at every extinction boundary.

Although there have been some claims along these lines, I believe that
the K-T boundary is the only well accepted instance.  Given the claimed
periodicity and the existence of at least one more drastic (although
earlier) extinction this seems somewhat damning.

One point which I haven't seen treated much is the question of whether
it is even necessary to explain the (debatable) periodicity using
astronomy.  Mass extinctions
appear to follow from some combination of climate and biology.
Dropping rocks on everything (or comets) is simply a crude way to
ensure this.  However, climate and ecology are coupled, extremely
complicated nonlinear systems.  One might add geological processes,
including continental drift, to the  list as the source of episodes
of intense volcanism, disruption of ecological systems due to
the creation of land bridges, and changes in climatic patterns.
It is my understanding that such systems frequently show oscillations
on somewhat unpredictable time scales that may appear, at first glance,
crudely periodic.

To take an extreme example, suppose mass extinctions are due entirely
to episodes of volcanism and the K-T boundary is either a coincidence
( comet(s) happened to hit close to such an episode) or simply reflective
of an unusually deep upwelling of mantle material during this episode.
Then one really needs to explain an approximate periodicity in certain
kinds of flow patterns in the Earth's core.  I don't think this would
strike anyone as particularly outrageous.

--
 I'm not afraid of dying     Ethan Vishniac, Dept of Astronomy, Univ. of Texas
 I just don't want to be     {charm,ut-sally,emx,noao}!utastro!ethan
 there when it happens.      (arpanet) [e-mail]
    - Woody Allen            (bitnet) [e-mail]

These must be my opinions.  Who else would bother?

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

Date: 19 May 89 19:15:24 GMT
From: [e-mail]  (Charles Daffinger)
Subject: Re: Magellan Status for 05/19/89 (Forwarded)

In article <[e-mail]> [e-mail] (Peter E. Yee) writes:
>
>            MAGELLAN STATUS
>            May 19, 1989
>
>
>    Daily momentum wheel desaturations continue as scheduled, twice
>daily, 00:45 a.m. and 12:45 p.m. PDT, project said today.  The daily

What are these momentum wheel desaturations?






-charles


--
Charles Daffinger  >Take me to the river, Drop me in the water<  [phone]
[e-mail]              {pur-ee,rutgers,pyramid,ames}!iuvax!cdaf
Home of the Whitewater mailing list:    [e-mail]

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

Date: 18 May 89 14:05:39 GMT
From: asuvax!anasaz![e-mail]  (Scott Gibson)
Subject: Re: New Orbiter Name Announced

In article <[e-mail]> [e-mail] (Marc Bonin) writes:
>
>Enterprise :  Obvious !
>Discovery:   the ship from 20001
                            ^^^^^
                ^^^^^
AAAAAHHHHHHHHH!  You mean this is really 19989??  I knew I was feeling
sort of run down.......( ;-) )

Scott

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

Date: 19 May 89 09:00:00 GMT
From: well![e-mail]  (Jef Poskanzer)
Subject: Re: Sun's invisible partner NEMESIS

In the referenced message, [e-mail] (Henry Spencer) wrote:
}Last I heard, this idea was no longer taken seriously by most people.  It
}appears unlikely that Nemesis's orbit would be stable against perturbations
}by other stars over billions of years.

It doesn't have to be stable for billions of years, just for the few
hundred million that we can see in the fossil record.  This specious
objection comes straight from a Nature editorial, by the way.

Read "The Nemesis Affair: A Story of the Death of Dinosaurs and the
Ways of Science", by David M. Raup, 1986.  Read "Nemesis: The Death Star",
by Richard Muller, 1988.  Then decide.
---
Jef

            Jef Poskanzer   [e-mail]   ...well!pokey
                      "Back off, man - I'm a scientist!"

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

Date: 19 May 89 16:05:44 GMT
From: dinl![e-mail]  (kevin w. holroyd)
Subject: Re: Magellan & SRB exhaust

In article <[e-mail]> [e-mail] (Marcus Hall) writes:
>        stuff deleted
>Are the windows considered more critical than the bottom tiles?  I guess they
        stuff deleted

Only when it comes time to land and you can't see outside.

--
*******************************************************************************
Kevin W. Holroyd            *
CFI Aspen Flying Club            * Got tired of last .signature file
Denver CO.                *
*******************************************************************************

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

Date: 19 May 89 23:40:16 GMT
From: trident.arc.nasa.gov![e-mail]  (Peter E. Yee)
Subject: Magellan Advisory (Forwarded)

JET PROPULSION LABORATORY

News Advisory   May 19, 1989



Editors:
The Magellan spacecraft, on a 15)month journey to Venus, will
perform a trajectory correction Sunday at 7 p.m. PDT. The
maneuver will increase the spacecraft's velocity 2.9 meters per
second, or about 6.6 miles per hour. It also will slightly alter
the course of the spacecraft's trajectory. Friday, Magellan was
moving at 59,970 miles per hour, relative to the sun.

Magellan, launched from the shuttle Atlantis May 4, is to map up
to 90 percent of the surface of Venus with imaging radar. It is
to be placed in Venus orbit Aug. 10, 1990. Seventeen days prior
to orbit insertion, Magellan will perform a second Trajectory
Correction Maneuver.

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

End of SPACE Digest V9 #451
*******************