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Subject: SPACE Digest V10 #41

SPACE Digest                                      Volume 10 : Issue 41

Today's Topics:
               Re: Stellifying Jupiter.
           Re: Interesting Apollo crew observations
             Re: NASA missions/time table
             Re: Apollo 11 program alarms
              Re: Impossible Space Goals
Science observations selected for NASA/ESA Hubble Space Telescope (Forwarded)
       Re: NASA Headline News for 08/30/89 (Forwarded)
      Re: Where the hell are electric-ion thrusters????
      Re: Was Voyager another damaging Apollo one-shot?
----------------------------------------------------------------------

Date: 5 Sep 89 05:46:45 GMT
From: mailrus!jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Stellifying Jupiter.

In article <2502@pur-phy> [e-mail] (Society of Physics Students) writes:
>    What about dropping a thermonuclear bomb into Jupiter?  Wouldn`t the
> explosion ignite the hydrogen and helium in the atmosphere, causing
>planetwide nuclear fusion? ...

In a word, no, any more than an underwater nuclear explosion on Earth would
ignite the hydrogen in our oceans.  (It's been done.)  (Underwater explosions,
I mean, not ignition!)  Fusion in ordinary hydrogen is inordinately slow,
as witness the fact that the Sun has been doing it for some billions of
years and is still almost all hydrogen.  Helium fusion is even worse.
--
V7 /bin/mail source: 554 lines.|     Henry Spencer at U of Toronto Zoology
1989 X.400 specs: 2200+ pages. | uunet!attcan!utzoo!henry [e-mail]

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

Date: 15 Aug 89 17:28:27 GMT
From: [e-mail]  (Andy Stadler)
Subject: Re: Interesting Apollo crew observations

In article <[e-mail]> [e-mail] (Danny Young) writes:
>The July Astronomy magazine quotes Buzz Aldrin's comments on standing on
>the moon: "I quickly discovered that I felt balanced--comfortably upright--only
>when I was tilted slightly forward.  I also felt a bit disoriented:  On Earth
>when one looks at the horizon, it appears flat.  On the Moon, so much smaller
>than the Earth and quit without high terrain (at least in the Sea of
>Tranquility), the horizon in all directions visibly curved down away from us."
>
>Were these sensations anticipated?  Are there other interesting observations
>that Apollo crews have made that perhaps came as a surprise to them?
>

If you look at any of the surface photos, especially a profile view, this
forward lean is quite evident....  But it's also very evident why:  the large,
heavy life support backpack.  Leaning forward moved the center of mass back
over the feet.

--Andy             [e-mail]

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

Date: 5 Sep 89 05:38:17 GMT
From: mailrus!jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: NASA missions/time table

In article <[e-mail]> [e-mail] (Ken Arromdee (600.429)) writes:
>>        12/08/1990 -- Galileo flies past Earth at an altitude of 620 miles.
>
>Is it going to take pictures?  (Would there be any reason not to take one,
>just for the heck of it?)

The grapevine says that there is talk of doing a full-blown study-the-
hell-out-of-it Earth/Moon encounter, as a combined rehearsal, test, PR
exercise, and opportunity to get some useful data.

Incidentally, I'm told that if you think that Earth encounter is close,
you should check out the Moon part of the encounter.  The number I heard
was 75 miles.  (I have *not* checked this and my source might perhaps have
been mistaken; I don't recall hearing about it before.)
--
V7 /bin/mail source: 554 lines.|     Henry Spencer at U of Toronto Zoology
1989 X.400 specs: 2200+ pages. | uunet!attcan!utzoo!henry [e-mail]

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

Date: 15 Aug 89 11:55:28 GMT
From: thorin!lhotse![e-mail]  (James Symon)
Subject: Re: Apollo 11 program alarms

In article <[e-mail]>, [e-mail] (Charlie Richter) writes:
>
> And the answer is ... Steve Bales.  Bales was the
> guidance officer for Apollo 11.  As such, he was the
> person who gave Eagle the GO to land despite the 1202
> and 1201 program alarms.
> --

In that CBS special it appeared that Armstrong made that decision. He
said something to the effect, "Hang tight, we're going" and just kep
going when the program alarm came up.

jim
[e-mail]
{decvax uunet}!mcnc!unc!symon

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

Date: 15 Aug 89 20:29:06 GMT
From: gem.mps.ohio-state.edu!ginosko!infinet![e-mail]  (Rob Horn)
Subject: Re: Impossible Space Goals

In article <[e-mail]> [e-mail] (Eugene Miya) writes:
>>In article <[e-mail]>, [e-mail] (Stainless Steel Gerbil [Joe Beckenbach]) writes:
>>}My two cents:  those in JFK's world saw the Moon as "impossibly far",
>
>Ain't hindsight wonderful?
>
>To understand why they used that adjective, you must get library books
>dated prior to 1961.  You will see the great unknowns at the time:
>Was the surface of the moon hard or miles of dust for a lander to sink?

There were even two series of Lunar probes launched to specifically
answer this and related questions.  It was nice back in the days when
you could have short turnaround simple missions.  Specific focused
goals and specific focused schedules are so much easier to work with
than ongoing generic projects.

I even recall one wonderful day when discussing some problem (I forget
what) someone seriously suggested designing and launching a simple
satellite to discover the answer.  Today you must politic for years to
create a new satellite.  I hope that some of the quick response and
creativity returns with some of the projects like cheapsat.


--
                Rob  Horn
    UUCP:    ...harvard!adelie!infinet!rhorn
        ...ulowell!infinet!rhorn, ..decvax!infinet!rhorn
    Snail:    Infinet,  40 High St., North Andover, MA

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

Date: 15 Aug 89 17:50:22 GMT
From: trident.arc.nasa.gov![e-mail]  (Peter E. Yee)
Subject: Science observations selected for NASA/ESA Hubble Space Telescope (Forwarded)

Paula Clegget-Haleim
Headquarters, Washington, D.C.                     July 19, 1989

Ray Villard
Space Telescope Science Institute, Baltimore, Md.


RELEASE:  89-121

SCIENCE OBSERVATIONS SELECTED FOR NASA/ESA HUBBLE SPACE TELESCOPE

     The Space Telescope Science Institute, Baltimore, Md., has
completed selection of the first science observation proposals
from the astronomy community to be carried out using the
NASA/European Space Agency (ESA) Hubble Space TelescopeMd
     The Hubble Space Telescope (HST), scheduled for launch in
March 1990, is the first major international optical telescope to
be permanently stationed in low-Earth orbit.  Capable of viewing
the universe with a tenfold greater resolution than ground based
observatories, the HST has a tremendous potential for fundamental
scientific breakthroughs in astronomy.  Observing opportunities
on the powerful space facility are open to the worldwide
astronomical community.

     "It is exciting to see the many excellant proposals and to
think of the scientific discoveries that will soon emerge when
the Hubble Space Telescope uncovers the mysteries of fundamental
scientific questions," says Neta Bahcall, Head of the institute's
Science Programs Selection Office.

     The selected observations will make use of HST's unique
capabilities to study a wide variety of astronomical objects,
from nearby planets to the horizon of the visible universe.  The
observations should help to dramatically improve current
understanding of the size, structure and evolution of the
universe.

     Among the accepted proposals are plans to search for black
holes in neighboring galaxies, to survey the dense cores of
globular star clusters, to better see the most distant galaxies
in the universe, to probe the mysterious core of the Milky Way
galaxy and to search for neutron stars that may trigger bizarre
gamma-ray bursts.

     The 162 proposals were accepted following an intensive
scientific peer review of 556 proposals submitted by astronomers
from 30 countries.  Approximately 20 percent of the proposals
were from member nations of the European Space Agency, a joint
partner with NASA on the HST project.

     The HST is such a powerful, new resource for optical
astronomy, that observing time was heavily oversubscribed.
During the first 12-month observing cycle, 11,000 hours of
observing time were requested, with only 1200 hours available.
The average length of an accepted observation is 10 hours.

     "Unfortunately, because of the high oversubscription rate,
many excellent proposals could not be accommodated," says
Bahcall. "We expect that the available observing time will be
somewhat larger in the second cycle, due to a higher anticipated
HST observing efficiency and a lower fraction of time committed
to guaranteed time observers (GTO)."

     When HST is launched, it will undergo a 7 month check-out
and instrument calibration period.  During that time some of the
first science observations will be made by the GTOs.  They are
the astronomers on the six teams which developed HST
instrumentation, as well those astronomers who contributed to the
design of the 12-ton observatory.

     General observer proposals will begin 7 months after launch
and most will be completed within a 12-month period, though a few
key projects will be extended over 3 years.  Slightly more than
half of HST's observing time for the first year of operation will
be available for general observers.  The remainder of the
observing time will be used by the GTO's.

     To utilize every moment of observing time and hence maximize
efficiency, HST is "over-booked" with accepted general observer
proposals by a ratio of 3:1.   One hundred eight accepted
proposals are high priority and represent 90 percent of HST
observing time.  The remaining 54 supplemental proposals
essentially "fly standby."  They will only be executed if
appropriate scheduling opportunities arise.

     Sixty-two scientists including 10 from ESA member nations
participated in the proposal review and selection process.  The
scientists were divided into six peer-review panels which covered
sub-disciplines in astronomy such as solar system, stellar
astrophysics, stellar populations, interstellar medium, galaxies
and clusters, quasars and active galactic nuclei.

     Each proposal was judged primarily for scientific
importance.  Other selection criteria took into account such
factors as the technical feasibility of the proposal and an
observer's need for the unique capabilities of HST.

     The ranked lists of proposals assembled by the various
panels were then reviewed by a cross-discipline Time Allocation
Committee (TAC).  Space Telescope Science Institute Director
Riccardo Giacconi made the final selection based upon a review of
the TAC's recommended list of proposals.

     The proposals now will go through a phase II process where
the guest observers will specify the technical details of their
observations.  The proposals then will be checked for technical
feasibility, such as availability of guide stars required to aim
the telescope in space and other possible problems.  At the
conclusion of phase II this fall, a catalog of approved
observations will be made available.

     The Space Telescope Science Institute is operated for NASA
under a contract with the Goddard Space Flight Center, Greenbelt,
Md., by the Association of Universities for Research in
Astronomy, Inc.  The institute is located on the Johns Hopkins
University campus in Baltimore, Md.

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

Date: 5 Sep 89 05:26:03 GMT
From: mailrus!jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: NASA Headline News for 08/30/89 (Forwarded)

In article <[e-mail]> [e-mail] (Steve Masticola) writes:
>Can the RTG be conserved by reducing power use, or are the instruments
>being shut off because there won't be adequate power available for
>them at that time? The former seems unlikely...

It is; the RTG decay rate is preordained.  I think either the "shutting
down instruments to conserve power" is really "eventually power will get
short, and we might as well turn them off now because they're no longer
useful", or somebody has misunderstood slightly.

>When is Voyager expected to meet the heliopause?

Good question.  Originally it was thought that it might happen well before
now.  I don't know what the current guesses are, but as far as I know they're
only guesses.

> Was any maneuvering
>done at Neptune to shorten this time?

Not as far as I know.  Science return from Neptune was by far the highest
priority.
--
V7 /bin/mail source: 554 lines.|     Henry Spencer at U of Toronto Zoology
1989 X.400 specs: 2200+ pages. | uunet!attcan!utzoo!henry [e-mail]

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

Date: 5 Sep 89 05:21:54 GMT
From: mailrus!jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Where the hell are electric-ion thrusters????

In article <[e-mail]> [e-mail] (Neal Woodall) writes:
>>>...fewer B2 bombers, and give that money to JPL for probes, including a full
>>>program of electric-ion engine probes to various parts of the solar system?
>
>>Because Congress isn't willing to move funds around like that.  If you feel
>>this is unfair... have you talked to *YOUR* Congressthing about it lately?
>
>It so happens that I am VERY involved in lobbying Congress...

Apologies for poor wording; that was meant as a broadcast exhortation, not
pointed at you specifically.

>Sure, the thrust is low, but the nice thing about electric-ion thrusters
>is the fact they have much greater delta-v potential because they are much
>higher specific impulse...

Mmm, do remember, though, that in a solar system with significant
gravitational fields, we need thrust as well as specific impulse.  If
thrust is much lower than the local force of gravity on your vehicle,
you generally get very inefficient and tedious trajectories.

>(I think that recently someone showed they are about
>an order of magnitude higher than the Saturn F1 or J2 engines in specific
>impulse)

Easily.  In fact the speed of light is the only *fundamental* limit on
the exhaust velocity of ion engines, as demonstrated by Fermilab (which
has an exhaust velocity of essentially c, although the thrust:weight
ratio is truly dreadful).

> AND the fact that they can run for 1000's of hours continuously.

This is a side effect of the high specific impulse, not a separate issue
(except insofar as durability of the thruster is an issue).
--
V7 /bin/mail source: 554 lines.|     Henry Spencer at U of Toronto Zoology
1989 X.400 specs: 2200+ pages. | uunet!attcan!utzoo!henry [e-mail]

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

Date: 5 Sep 89 05:43:34 GMT
From: mailrus!jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Was Voyager another damaging Apollo one-shot?

In article <[e-mail]> [e-mail] (Jeff Goldader) writes:
>We have just *barely* scratched the surface with the Voyagers...
>It takes a long time to get to the planets...

It takes quite a short time to get to Mercury.  Mariner 10 scratched the
surface there in 1975, nearly fifteen years ago.  We haven't been back.
There are no plans to go back.

I won't even mention the Moon... :-(

I hope Tom doesn't have a point... but I fear he may.  Cross your fingers.
--
V7 /bin/mail source: 554 lines.|     Henry Spencer at U of Toronto Zoology
1989 X.400 specs: 2200+ pages. | uunet!attcan!utzoo!henry [e-mail]

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

End of SPACE Digest V10 #41
*******************