Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT_ZIP/spacedig/V09_4/V9_473.ZIP/V9_473

Internet Message Format | 1991-07-08 | 16KB

Return-path: <[e-mail]>
X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson
Received: from holmes.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr1/ota/space/[e-mail] (->+dist+/afs/andrew.cmu.edu/usr1/ota/space/space.dl) (->ota+space.digests)
          ID </afs/andrew.cmu.edu/usr1/ota/Mailbox/4YWrdGm00UkZIcsk5V>;
          Tue,  6 Jun 89 03:16:35 -0400 (EDT)
Message-ID: <[e-mail]>
Reply-To: [e-mail]
From: [e-mail]
To: [e-mail]
Date: Tue,  6 Jun 89 03:16:24 -0400 (EDT)
Subject: SPACE Digest V9 #473

SPACE Digest                                      Volume 9 : Issue 473

Today's Topics:
             Re: Private Space Companies
           OSC Hercules Launch Information
         Re: Venus & the Greenhouse effect..
         Re: Venus & the Greenhouse effect..
       Wanted: software to predict satellite sightings
Smith appointed Deputy Director, NASA Stennis Space Center (Forwarded)
               Re: Spiral arms
         Re: Venus & the Greenhouse effect..
         Re: Venus & the Greenhouse effect..
----------------------------------------------------------------------

Date: 2 Jun 89 18:26:30 GMT
From: jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Private Space Companies

In article <[e-mail]> [e-mail] writes:
>>  the KC-135 and the 707 are **not** the same aircraft...
>
>This is not a popular misconception.  Let's look at Jane's All the
>World's Aircraft, which is a very authoritative source.  On page 238
>of the 1976-77 edition we find the following...

Note carefully what Jane's is saying:  it is saying that the KC-135 and
the 707 were both derivatives of the privately-funded "dash 80" prototype,
that Boeing felt it advisable to ask USAF permission before building the
707, and that the 707 also entered military service as the VC-137 (and
other related designations).

>Thus we see that a privately developed prototype became the VC-137
>(probably A) which turned into the KC-135...

Uh, please re-read your own excerpt from Jane's, carefully.  The KC-135
order came first, after which Boeing asked for (and got) permission to
work on a commercial dash-80 derivative in parallel, and said derivative
eventually became the 707 and the VC-137.

I did some digging in my library at home.  Said library unfortunately runs
more to fighters than transports, but I hit the jackpot in Bill Gunston's
"USAF: The Modern US Air Force".  For those who don't know the name, Gunston
today is a freelance military-aviation author, but back in the mid-50s he
was technical editor of Flight International, the British counterpart of
Aviation Week.  I think we can assume he knows what he's talking about.
In his section on the C-135 family, he says:

    Boeing risked more than the company's net worth to build a
    prototype jetliner, first flown in July 1954.  An important
    factor behind the gamble was the belief that the USAF would
    buy a jet tanker/transport to replace the Boeing KC-97 family,
    and this belief was justified by the announcement of an initial
    order for 29 only three weeks after the company prototype flew,
    and long before it had done any inflight refuelling tests.  The
    KC-135A Stratotanker differed only in minor respects from the
    original prototype, whereas the civil 707 developed in a parallel
    programme was a totally fresh design with a wider fuselage,
    airframe of 2024 alloy designed on fail-safe principles and
    totally revised systems...

And under VC-137:

    These aircraft bear no direct relationship to the prolific C-135
    family but were commercial airliners... bought off-the-shelf...

>The Air Force paid for the YC-14 prototypes, since this was back in
>the era of fly-offs.  This certainly contradicts the "Boeing has never
>been paid by the government to build an aircraft" line...

I don't think that I quite said that, given that the B-52, among others,
was a Boeing product.  But they've never had major government subsidies
to build a later-successful airliner.  (That last bit of weasel-wording
is necessary because of an example you missed:  the American SST.)

>... Boeing is
>much less concerned about ideological purity than some people on the
>net are.  Rather, they'll take any advantage they can (IMO as they
>should) to continue building successful and profitable aircraft.

Quite true.  And more power to them.  Unlike (say) McDonnell-Douglas,
while they are happy to take government money if offered, they don't
quake if the government scowls at them.
--
You *can* understand sendmail, |     Henry Spencer at U of Toronto Zoology
but it's not worth it. -Collyer| uunet!attcan!utzoo!henry [e-mail]

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

Sender: [e-mail]
Date: 2 Jun 89 10:43:20 PDT (Friday)
Subject: OSC Hercules Launch Information
From: [e-mail]
Cc: [e-mail]

Does anyone on the net have any info about where OSC is in their
development of Hercules ?  Specifically I was looking for the date that
they expect to do the first launch.

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

Date: 2 Jun 89 17:50:45 GMT
From: jacobs.CS.ORST.EDU![e-mail]  (Kelly St.Clair)
Subject: Re: Venus & the Greenhouse effect..

> [Is there any reason that Venus could not be cooled and terraformed?]

Is there any reason (besides needing space so that we can keep breeding like
flies)s) that we should?

Most important of all:
Is there anything that gives us the *RIGHT* to remake another world in our
own image?

(Old discussion, I know, but I thought it should be said...)

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

Date: 2 Jun 89 23:10:08 GMT
From: haven!aplcen![e-mail]  (Ken Arromdee)
Subject: Re: Venus & the Greenhouse effect..

>Is there any reason (besides needing space so that we can keep breeding like
>flies)s) that we should?
>Is there anything that gives us the *RIGHT* to remake another world in our
>own image?

The same thing that allows us to farm, mine, build houses on, etc... our own
planet.  "Is there any reason (besides needing space so that we can keep
breeding like flies) that we should move out of the tropical regions in which
we evolved into climates which require us to ruin the natural surroundings
with dwellings to protect us from temperature extremes?  Is there anything
which gives us the *RIGHT* to build fires, grow plants, just to benefit our
own selfish species, etc..."
--
"The fact is self evident from the text and requires no supporting argument."
  --Tim Maroney

Kenneth Arromdee (UUCP: ....!jhunix!ins_akaa; BITNET: g49i0188@jhuvm;
     INTERNET: [e-mail]) (please, no mail to arrom@aplcen)

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

Date: 1 Jun 89 10:18:02 GMT
From: mcvax!ukc!mucs![e-mail]
Subject: Wanted: software to predict satellite sightings

The regular postings of orbital elements sure *look* interesting,
... but does anyone have PD software that can use these elements to
predict sightings?

Anything for UNIX or IBM PCs would be appreciated...

Mario Wolczko
   ______      Dept. of Computer Science    Internet:   [e-mail]
 /~      ~\    The University               USENET: mcvax!ukc!man.cs.ux!mario
(    __    )   Manchester M13 9PL           JANET:      [e-mail]
 `-':  :`-'    U.K.                         Tel: [phone]  (FAX: 6280)
____;  ;_____________the mushroom project____________________________________

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

Date: 2 Jun 89 20:28:59 GMT
From: trident.arc.nasa.gov![e-mail]  (Peter E. Yee)
Subject: Smith appointed Deputy Director, NASA Stennis Space Center (Forwarded)

David W. Garrett
Headquarters, Washington, D.C.                       June 2, 1989


RELEASE:  89-85

SMITH APPOINTED DEPUTY DIRECTOR, NASA STENNIS SPACE CENTER


     The appointment of Gerald Smith as deputy director of NASA's
John C. Stennis Space Center (SSC), Miss., was announced today by
Center Director Roy Estess.  Smith will assume his new duties on
June 17.

     Since 1986, Smith has managed the solid rocket booster
project in the Shuttle Projects Office at NASA's George C.
Marshall Space Flight Center (MSFC), Huntsville, Ala.  In April
1985, he was detailed to NASA Headquarters, Washington, D.C., as
acting chief, Engine Programs Branch, Shuttle Propulsion Division
in the Office of Space Flight.

     Smith joined MSFC in September 1961 as a member of the
former Structures and Mechanics Division.  From 1961 to 1963, he
served in the U.S. Army and was then re-employed at Marshall in
the Propulsion Division of the former Propulsion and Vehicle
Engineering Laboratory.

     In 1965, he left Marshall to work as a test and evaluation
engineer in the Large Jet Engine Department at the General
Electric Company.  He returned to Marshall in 1967 as part of the
center's structures and propulsion effort.

     In 1974, he was assigned to the Office of the Associate
Director for Engineering in the Science and Engineering
Directorate.  In 1983, he became deputy manager of the Space
Shuttle maine engine project in the Shuttle Projects Office.  In
September 1984, he was appointed deputy associate director for
engineering in the Science and Engineering Directorate.

     Smith earned bachelor's and master's degrees in aeronautical
engineering at Auburn University, Ala., and a master's degree in
administrative science at the University of Alabama, Huntsville.

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

Date: 2 Jun 89 18:30:19 GMT
From: frooz![e-mail]  (Steve Willner)
Subject: Re: Spiral arms

First, usc!csun!solaria![e-mail]
(Stephen Walton) wrote:
>Contrary to popular belief, the steller density
>(stars per cubic parsec) in spiral arms is the same as between the
>arms; it is just that most of the new, hot, and therefore bright stars
>are in the arms, causing them to stand out.

Then in article <[e-mail]>, by
[e-mail] (Peter Scott) replied:
> ... but I thought that arms in spiral galaxies were thought to be
> compression waves and therefore at different times different parts
> of the galaxy would be in the arms, which would preclude stellar
> differentiation on the basis of age?  Isn't the differentiation
> between the disk and the halo, the Pop. I and II stars?

These questions touch on a very active field of current research.  As
always, there is an interplay of theory and observation.  I'll try to
outline current ideas.  We should know a lot more in five years.

Spiral galaxies are conventionally considered to be made up of the
following parts: the "bulge" in the middle (round, radius around 3000
light-years); the "disk", which is very thin (say 500 ly) but of
large radius (say 50000 ly); and the "halo", which is roughly
spheroidal and about the same radius as the disk.  Some galaxies also
have "bars," which are bigger than the bulge but smaller than the
disk.  The Sun is located in the disk of the Milky Way galaxy, about
25000 ly from the center.  Halo stars generally have lower metal
abundance than disk stars and are called "Population II" stars versus
"Pop. I" in the disk.  Less is known about bulge stars, but it now
looks as though at least some of them have higher metal abundances
than disk stars.  Every star orbits in the gravitational field
established by all the other mass of the galaxy.

In the last several years, both theory and observation have come to
agree that most of the mass of spiral galaxies is in the halo but is
in some invisible form.  There simply are not enough halo stars
observed to add up to the necessary mass.  (In describing these
results for the Milky Way, the late Bart Bok used to refer to the
"bigger and better Galaxy.")  The nature of the invisible matter is
unknown, though it cannot be stars (say 0.1 solar mass or greater).
I think massive black holes (>10 solar masses) are also ruled out.
(This "hidden mass" is NOT the same as the "missing mass" supposedly
needed to close the Universe, though of course the two might be made
out of the same stuff.  The amount of "hidden mass" is only 1/50 to
1/10 of the "missing mass.")

Theory says that perturbations to the mass distribution in galaxies
can last for significant times if the perturbations have the right
form.  One form is spiral density waves.  The "pattern" of the waves
rotates at a different speed than do the actual stars in the disk, so
any given star alternately passes through high- and low-density
portions of the wave.  The density contrast is modest but non-zero.
An important research question today is how the observed spiral arms
are related to these theoretical density waves.

Spiral arms are much more conspicuous in blue light than in red
light.  The interpretation is that massive (thus blue and
short-lived) stars are preferentially concentrated in the spiral
arms, more concentrated in fact than stars of lower mass.  The most
likely explanation is that the density increase associated with
spiral density waves somehow enhances star formation.  The abundance
of bright stars - stars so massive that their lifetimes are less than
a galactic rotation period - is thus higher "downstream" of the
density waves.  Less massive stars, with long lifetimes, should be
slightly concentrated in the density wave itself, but these stars are
faint and thus hard to observe.  (Most of the visible light of a
"typical" galaxy comes from stars more massive than 2 solar masses,
whereas most of the mass is in stars less massive than the Sun.)
Infrared images, which are just now starting to be obtainable, should
give a much better picture of the mass distributions in galaxies.

I have cross-posted this to sci.astro and (with luck) directed
follow-ups there.  Please check the newsgroups line.

(P.S.  We have suffered two independent "system upgrades" in our mail
path, so please try again if you recently have failed to reach me.)


Steve Willner            Phone [phone]         Bitnet:   willner@cfa
60 Garden St.            FTS:      830-7123           UUCP:   willner@cfa
Cambridge, MA 02138 USA                 Internet: [e-mail]

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

Date: 2 Jun 89 15:59:13 GMT
From: asuvax!anasaz![e-mail]  (Scott Gibson)
Subject: Re: Venus & the Greenhouse effect..

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>
>into the details and established that Earth would not have a runaway
>greenhouse effect even with far more CO2 than it has now.  There are
>a number of complications, like the effect of clouds on climate (they
>tend to cool the surface, on the whole).  The "habitable zone" around

I have seen this comment several times, and don't really understand it.
The surface of Venus is *completely* obscured by clouds.  While it makes
sense (or seems to) that clouds, by shading the surface, cool it - this
has not done much for the surface of Venus.  Clearly, the presence of
clouds does not necessarily stop a runaway greenhouse effect.

Of course, Venus *is* a little closer to the sun......

Scott

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

Date: 3 Jun 89 22:09:51 GMT
From: jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Venus & the Greenhouse effect..

In article <[e-mail]> andrew@berlioz (Eraserhead @ The Noblest Explosion            ) writes:
>Is there any strong a priori reason why Venus could not be cooled by this
>or any other terraforming idea? ...

As I recall, from papers in JBIS and other places, the notion is not quite
impossible but it is difficult.  Getting rid of all that atmosphere is hard.
There are other problems in making Venus habitable too, like a grave shortage
of water and an excessively long rotation period.
--
You *can* understand sendmail, |     Henry Spencer at U of Toronto Zoology
but it's not worth it. -Collyer| uunet!attcan!utzoo!henry [e-mail]

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

End of SPACE Digest V9 #473
*******************