Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/spacedig/v08/v8_315.txt

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Date: Fri, 5 Aug 88 01:04:39 PDT
From: Ted Anderson <[e-mail]>
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Subject: SPACE Digest V8 #315

SPACE Digest                                      Volume 8 : Issue 315

Today's Topics:
           Re: space news from June 6 AW&ST
           Re: space news from May 30 AW&ST
         Re: Time skew -- does it hurt SETI?
              Re: space studies
          Re: query about 'escape velocity'
 Balloon campaign will seek evidence of antimatter galaxy (Forwarded)
                  Space Junk
               The Face on Mars
                Lithium cells
                Digital Images
          Re: query about 'escape velocity'
----------------------------------------------------------------------

Date: 28 Jul 88 19:25:46 GMT
From: att!chinet!mcdchg!clyde!watmath!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: space news from June 6 AW&ST

In article <[e-mail]> [e-mail] (Floyd McWilliams) writes:
>    Re the planned Jupiter-Pluto flight by the Voyager spare:
>How long would such a flight take?  Since Pluto is now closer to the
>sun than Neptune, would it take much longer than the 12-year trip by
>Voyager 2?  ...

I don't remember the numbers, and there may even have been a Saturn
encounter in the middle, but yeah, it was a fairly rapid trip.  Maybe
even faster than Voyager 2, because Uranus is actually not on a direct
course for Neptune.
--
MSDOS is not dead, it just     |     Henry Spencer at U of Toronto Zoology
smells that way.               | uunet!mnetor!utzoo!henry [e-mail]

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

Date: 28 Jul 88 19:30:26 GMT
From: att!chinet!mcdchg!clyde!watmath!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: space news from May 30 AW&ST

In article <[e-mail]> [e-mail] (John Pantone) writes:
>...I am, however, not too thrilled
>to see an editorial comment which seems to imply that just because the
>Soviets may (or may not) be getting tired of our "studies" that we
>should fall through our a__holes trying to please them, or get
>something done to satisfy or placate them.

Not "just" because the Soviets are getting tired of it.  Because everybody
who wants to see action in space, including prospective international
partners (not limited to the USSR), is getting sick of the US's inability
to actually accomplish anything.  The US space program currently specializes
in studying missions rather than doing them.  And when a possible partner
actually proposes *doing* something, what answer do they get from the US
government?  "Great idea, let's study it for a few more years."  Feh.
--
MSDOS is not dead, it just     |     Henry Spencer at U of Toronto Zoology
smells that way.               | uunet!mnetor!utzoo!henry [e-mail]

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

Date: 28 Jul 88 21:04:55 GMT
From: att!chinet!mcdchg!clyde!watmath!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Time skew -- does it hurt SETI?

In article <[e-mail]> [e-mail] (Martin Sodos) writes:
>... If they are
>behind us they are somewhat before the time of their equivalent of the
>Greeks, and there is no hope of communication. If they are ahead of us,
>they are probably so advanced as to be almost unrecognizable...

This hurts CETI but not SETI (at least not to such an extent).  One would
tentatively expect that a race would be observable for quite a while even
after they advanced to the point where they weren't interested in talking
to us.  Unless our current grasp of physics is grossly inadequate, the
electromagnetic spectrum is unlikely to be replaced by anything better
as a species advances.

The single most plausible reason for seeing no signs of extraterrestrial
intelligence is that a species which advances not far beyond our own
changes so radically that it loses interest in communication, space
exploration, etc., at least in the forms we recognize.  There is no way
to test this hypothesis, unfortunately, since it essentially claims that
extrapolation from our current knowledge is invalid.
--
MSDOS is not dead, it just     |     Henry Spencer at U of Toronto Zoology
smells that way.               | uunet!mnetor!utzoo!henry [e-mail]

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

Date: 29 Jul 88 17:27:03 GMT
From: [e-mail]  (Eugene Miya)
Subject: Re: space studies

This is not for space.shuttle, this is more for sci.space.
In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>"Great idea, let's study it for a few more years."

No, you have it all wrong! s/study/computer simulate/  # ;-)

Another gross generalization from

--eugene miya, NASA Ames Research Center, [e-mail]
  resident cynic at the Rock of Ages Home for Retired Hackers:
  "Mailers?! HA!", "If my mail does not reach you, please accept my apology."
  {uunet,hplabs,ncar,decwrl,allegra,tektronix}!ames!aurora!eugene
  "Send mail, avoid follow-ups.  If enough, I'll summarize."

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

Date: 29 Jul 88 18:28:39 GMT
From: cfa!cfa250![e-mail]  (Jonathan McDowell)
Subject: Re: query about 'escape velocity'

From article <[e-mail]>, by [e-mail]:
[... question about escape velocity..]

No, your question is perfectly sensible and your argument is correct.
There is absolutely nothing to stop you going all the way to the Moon
(or Pluto, for that matter) at a nice steady 55 mph (:-) if you have a
nice steady thrust source.  This takes an AWFUL lot of fuel though, and
if your engine stops you find yourself on an orbit you didnt want to be
on.  You've given yourself a lot of potential energy and no kinetic
energy, so if you start freely falling you are at the apogee of your
orbit and will soon change all that PE into huge amounts of KE heading
back towards the Earth very fast..[ "Ground...  yes, ground...  I wonder
if it'll be friendly?"] You might also have a problem landing on the
Moon once you got there; its radial velocity is small, but its orbital
velocity is large..  you sure won't be going at 55 mph relative to it.
Ever tried to step off a moving train?

 'Escape velocity' is just the velocity needed to leave the Earth
WITHOUT any further thrust; that is, if you freely fall with this
velocity (in a direction away from the Earth!) you are on a parabolic
orbit that will not return you to the Earth.

When solar sailing and other continuous thrust propulsion methods become
common, we may hear a lot less talk about escape velocity, but the
relative velocities of departure and destination points will still be
important.

Jonathan McDowell

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

Date: 29 Jul 88 19:07:23 GMT
From: [e-mail]  (Peter E. Yee)
Subject: Balloon campaign will seek evidence of antimatter galaxy (Forwarded)

Paula Cleggett
Headquarters, Washington, D.C.                     July 29, 1988

Patricia M. Simms
Goddard Space Flight Center, Greenbelt, Md.

RELEASE:  88-106

BALLOON CAMPAIGN WILL SEEK EVIDENCE OF ANTIMATTER GALAXY


     NASA will launch three huge balloons in Canada next month to
search for cosmic rays, including those that could provide
evidence of galaxies made of antimatter.

     Antimatter consists of particles with electrical charges
opposite those of "common" matter, which constitutes Earth's
material.  When antimatter and matter collide there is a mutual
and complete annihilation, releasing energy far greater in
proportion then energy released by nuclear fission or fusion.

     Whether antimatter could ever be created in sufficient
supply and harnessed to provide useful energy is a challenging
question.

     The flights will begin Aug. 2, in a month-long campaign that
is part of the NASA Balloon Program managed by the Goddard Space
Flight Center's Wallops Flight Facility, Wallops Island, Va.

     Balloons that will lift three cosmic ray experiments to
approximately 120,000 feet will be launched from Prince Albert
Saskatchewan Airport, approximately 300 miles north of the
U.S./Canadian border.

     Scientific balloons are utilized to carry large research
payloads with scientific instruments to make measurements at
altitudes above 99 percent of the Earth's atmosphere.  They are
made of a thin polyethylene material and are more than 350 feet
in diameter at full inflation.  These balloons provide unique
experiment platforms for measurements at altitudes in the upper
stratosphere.

     Personnel from WFF and the National Scientific Balloon
Facility, Palestine, Texas, will provide the launching and
operational flight support at the primary operations site in
Prince Albert.  Personnel from WFF also will provide downrange
telemetry tracking support at Edmonton, Alberta.

     Principal investigators for this campaign are Dr. Steve
Ahlen, Boston University; Dr. W. Robert Binns, Washington
University; and Dr. Steve Schindler, California Institute of
Technology.

     Ahlen's extragalactic antimatter experiment is a 4,500-pound
payload that will search for heavy anti-nuclei (anti-silicon to
anti-iron), and will be flown on a 28.4 million cubic foot
balloon.  The observed anti-nuclei are expected to provide
evidence for the existence of galaxies made completely of
antimatter.  Scientist believe this discovery could prove to be
extremely useful for understanding the annihilation process
between matter and antimatter in the creation of galaxies.

     Binns' payload, called the scintillating optic fiber
experiment is a 1,200-pound cosmic ray isotope experiment that
will utilize newly-developed range and trajectory-defining
detectors based on scintillating fiber optics.  It also will be
carried aloft by a 28.4 million-cubic-foot balloon.

     Schindler's 2,700-pound payload, to be carried on a 23.3
million-cubic-foot balloon, is the high energy isotope
spectrometer telescope.  This experiment employs a combination of
scintillators and counters to form a cosmic ray isotope
spectrometer capable of measuring the isotopic composition of
cosmic rays from helium to nickle.

     The mission is part of the overall NASA Balloon Program,
managed at Wallops.  The program provides 40-45 balloon flights a
year from locations around the world.

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

Subject: Space Junk
Date: Fri, 29 Jul 88 17:06:33 -0400
From: Fred Baube <[e-mail]>


An article in EE Times (July 25, page 21) declares that "Space
Junk Threatens Future Missions", according to NASA.  Spacecraft
are now more likely to be struck by orbital debris than by
micrometeorites.  In LEO, 1-to-10 cm objects cause the most
concern; NASA plans to release by the end of the year a radar
to detect such objects.

The Novenber 1986 Ariane breakup "instantly created 500 large
pieces of debris and instantly increased the total number of
objects orbiting the Earth by about 7%".

"The average time between collisions that might be damaging to an
orbiter at 300 km is 71 years, based on 1988 debris density ..
but if current trends continue, the time period drops to 26 years
for the density projected for 2000 and to 8 years for the
projected 2010 density."

And now for the kicker ..

"Carried to its logical conclusion, space debris in LEO's could
grow to the point where they are self-regenerative [and] the rate
of debris generation .. will exceed the rate of debris generation
by natural sinks."

/f

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

Subject: The Face on Mars
Date: Fri, 29 Jul 88 17:15:26 -0400
From: Fred Baube <[e-mail]>


World Weekly News cover story, August 9:

"Face On Mars Beams Warning to Earth" (with cover photo)

Story on page 5, with another photo captioned,

"Mile-long monument, center of photo, houses the Martian tele-
vision transmitter that has been sending the Earth stark images
of a long-dead civilization. Scientists who have seen the night-
marish pictures beamed from the gigantic face say they were
made by a race battling a deadly plague."

Named are "Swiss astronomer Ludin Pasche" and "Dr Lars-Tvar
Carlsson, the noted Swedish astronomer".

"It shows thousands and thousands of wretched souls dying in the
streets .. The suggestion is that the planet had been stricken
with a deadly plague."

More seriously, isn't there more to it than just the "face" ?
Aren't there some interesting geometrical relationships among
other objects in the area ?

#include <disclaimer.h>

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

Sender: "chaz_heritage.WGC1RX"@xerox.com
Date: 29 Jul 88 08:25:54 PDT (Friday)
Subject: Lithium cells
From: "chaz_heritage.WGC1RX"@xerox.com

Some reported explosions of lithium cells are due not to short-circuiting but to
application of AC.

Several reports of lithium cell explosions have appeared in 'Electronics and
Wireless World', a UK professional electronics magazine not given to
sensationalism. In all cases the lithium cells were part of a power supply
system which operated normally from mains AC, but relied on the lithium cells
for backup when mains power was disconnected. Failure of sufficient components
to allow mains AC (at 240V/50Hz in UK) to be applied to the cells caused them
not merely to outgas but to explode with great violence. In one case a rack of
expensive apparatus was seriously damaged; in another a laboratory suffered
structural damage assessed by its reporter as being similar to that which might
be caused by a small hand-grenade.

Since in the astronautics application no high-voltage AC will be present in the
circuit, there appears to be no risk of such violent explosions. Assessment of
the outgas hazard is clearly in the hands of experts.

Regards,

Chaz

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

Date: 29 Jul 88 18:50:33 GMT
From: rochester!ur-tut![e-mail]  (Tony Giaccone)
Subject: Digital Images


Hi folks,

I'm hoping someone out there can help me out. I'd like to get some of the raw
digital images sent back by either Viking, or Voyager, or both. Does anyone
know if this stuff is availible to the general public and if there's a cost
associated with it. The best news would be that someone out there has copies
of some of these images that I could ftp to my local machine. However, I'll
take them anyway I can get them (within reason, paper tape is probably not
acceptable :-).


                                       Thanks,

                                        Tony Giaccone

                    [e-mail]
                    cornell!rochester!ur-tut!giaccone

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

Date: 29 Jul 88 19:44:52 GMT
From: cfa![e-mail]  (Bill Wyatt)
Subject: Re: query about 'escape velocity'

In article <[e-mail]>, [e-mail] (Jonathan McDowell) writes:
> From article <[e-mail]>, by [e-mail]:
> > [... question about escape velocity..]
>
> No, your question is perfectly sensible and your argument is correct.
> There is absolutely nothing to stop you going all the way to the Moon
> (or Pluto, for that matter) at a nice steady 55 mph (:-) if you have a
> nice steady thrust source.  This takes an AWFUL lot of fuel
> [...]
>       so if you start freely falling you are at the apogee of your
> orbit and will soon change all that PE into huge amounts of KE heading
> back towards the Earth very fast.
[...]>
>  'Escape velocity' is just the velocity needed to leave the Earth
> WITHOUT any further thrust; that is, if you freely fall with this
> velocity (in a direction away from the Earth!) you are on a parabolic
> orbit that will not return you to the Earth.
[...]

The above is correct except I think you have to emphasize that the
escape velocity varies with the square root of the distance from the
Earth's (or other gravity well's) center. Thus, if you have sufficient
thrust to move away from the Earth at 55 mph, I calculate that
somewhere in the vicinity of Jupiter's orbit you'll be at the escape
velocity of Earth. After that point, even stopping the thrust will not
let you fall back to Earth (assuming no perturbations, etc.), although
you'd presumeably orbit or fall into the Sun!

A better way to think of this is that you are in a potential well,
with the Earth at the bottom, and you need to expend some amount of
energy to move up the sides of the well. The total amount of
energy needed to get out of the well (i.e. reach infintely up the
sides of the well) is constant, but the increment from a given
height decreases as you move outward.

Bill    UUCP:  {husc6,ihnp4,cmcl2,mit-eddie}!harvard!cfa!wyatt
Wyatt   ARPA:  [e-mail]
         (or)  [e-mail]
      BITNET:  wyatt@cfa2
        SPAN:  cfairt::wyatt
--

Bill    UUCP:  {husc6,ihnp4,cmcl2,mit-eddie}!harvard!cfa!wyatt
Wyatt   ARPA:  [e-mail]
         (or)  [e-mail]
      BITNET:  wyatt@cfa2
        SPAN:  cfairt::wyatt

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

End of SPACE Digest V8 #315
*******************