Greetings, greetings fellow email readers,

Here's your reminder -- AAS meeting Friday December 1st, 8:00pm, in room 302
of the aerospace building.
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For anyone who missed the November meeting, you missed some of the most
beautiful hi-res images from Hubble of the star forming regions in M-16
shared by Rhon at his SUN workstation..
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Well , it's just over a week now until Galileo sends its probe into the
Jovian atmosphere.  It's certainally had its share of problems. Let's hope
all goes well.  Can anyone with access to NASA Select tape it for a future
Here is a file  from JPL giving "Galileo Amazing Facts":

A new amazing fact about the Galileo mission to Jupiter appears on the
Galileo home page every day: .

Here are the Galileo amazing facts that have appeared so far:

The Galileo probe weighs 339 kilograms (750 pounds) and will enter the
atmosphere at a top speed of 170,000 kilometers per hour (106,000 mph), or
about 50 times faster than a bullet shot out of a rifle. The probe will
experience deceleration forces as high as 230 times Earth's gravity. In
about two minutes, the orbiter's speed will be slowed to about 1,600
kilometers per hour (1,000 mph) as it begins its 75-minute mission to
measure the planet's
atmosphere and clouds, while descending into the dense atmosphere under its
parachute. It's possible that the probe will also encounter lightning and rain.
Engineers have taken several steps to boost the performance of the ground
antennas that will be receiving Galileo's signals. One trick is to use
arrays of antennas instead of single antennas. How big (in diameter) would a
antenna be to provide the same performance as, say, the combination of the
Canberra Deep Space Network site, the Parkes Radio Telescope, and the
largest Goldstone antenna? 125 meters (410 feet)! That's about the distance
from home
plate to the wall in center field in Shea Stadium!
There's usually not that much dust for Galileo to plough through: a 1300
square foot house has maybe 290 cubic meters of space inside (about 10,000
cubic feet). At a usual interplanetary dust density of .00006 particles per
meter, you'd find one particle of dust in every 57 houses! Equivalently,
that's the volume that you'd get if you covered a football field with a 4
meter high roof-- and you'd only find one dust particle in that entire volume!
How big are those dust motes that were slowing Galileo? The dust motes are
.01 to .1 micrometers in diameter, which is 1/100th to 1/10th the size of
airborne dust that you might see floating in sunlight in front of a window,
or, several
hundred times smaller than a human hair.
Galileo was somewhat slowed by having to plough through a dust storm
originating from Jupiter--after three weeks, Galileo's speed dropped by a
whopping 25 angstroms per second (1 angstrom is one ten-billionth of a meter,
or about 4 billionths of an inch)!
The Galileo spacecraft is designed to survive extreme environmental
hardship. The temperatures on various parts of Galileo can range from -220
to +220 degrees celsius. The average radiation dose per minute absorbed by
during its orbital mission is equivalent to what the average person receives
in a whole year on Earth. On 7 December, as it makes its closest approach to
Jupiter, the radiation dose per minute to Galileo will exceed by several times
what a person on Earth would receive in their entire lifetime!
Jupiter's volume is about 1,400 times that of the Earth. In fact, its volume
is half again bigger than all of the Solar System's other planets, moons,
asteroids, and comets combined.
The radio signals from Galileo will be incredibly weak (about a billion
times fainter than the sound of a transistor radio in New York as heard from
Los Angeles). Radio science tries to measure effects that are very minute (about
the same as measuring the distance between Los Angeles and New York to the
accuracy of a human hair).
It's not necessarily true that the shortest distance between two points is a
straight line: as of November 15, 1995, Galileo still has 9,329,160
kilometers to travel along the curved arc that will take it to Jupiter.
However, if you
drew a straight line between the spacecraft and Jupiter on November 15,
they'd be separated by 16,141,701 kilometers. What's going on? If Galileo
headed out for where Jupiter is right now, it would arrive to find Jupiter
long gone--the
planet's orbital motion would have carried it further along its path around
the Sun. Instead, the spacecraft is heading towards the point where its
trajectory and Jupiter's orbit will intersect. Since Jupiter's speed going
around the Sun
is much faster than Galileo's current speed with respect to the Sun,
Jupiter's orbital motion will eat up much of the distance between spacecraft
and planet. That means that Galileo itself doesn't have to travel as far.
Galileo has already bagged a number of scientific firsts, including: the
first close-up look at an asteroid (Gaspra), the first discovery of an
asteroid moon  (Ida's moon Dactyl), the first and only documented direct
observation of a collision between solar system bodies (the impact of Comet
Shoemaker-Levy 9 with Jupiter), and the first global scale multi-spectral
(i.e. using several different wavelengths of light) imaging of the Moon's
far side.
Typical home insulation has a rating R=19, and is 4" thick. Galileo's
insulating blankets are 3 times as effective, and 1/20th the thickness
(2/10ths of an inch thick). The spacecraft insulation is 65 times "better"
than the fiberglass insulation that you'll find in your home!
Since Galileo is going into orbit around Jupiter (unlike the two Voyager
spacecraft, which flew by the planet), it can fly by Jupiter and its moons
at far closer distances than did Voyager, which means that Galileo's
pictures will
be a dramatic improvement over those from Voyager. Comparing Voyager images
with those to be sent back from Galileo is like viewing a book at the base
of the Empire State Building from the top story, as opposed to holding that
book in your hands.
Galileo's power sources, radioisotope thermo-electric generators, are
putting out only about 520 watts on 7 December. That's not even enough to
run a kitchen toaster!
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A Puzzler (from the ASTRO Mail List) :
	Who am I, what did I do, what did I predict?

	In the days of yore, I wrote before those tiny things were found.
	And in advance,without a glance, envisioned both go round.
	Only fiction? Firm prediction, with orbits neatly bound?
	But years must pass. Then through a glass they'll prove my vision sound.

Hints: in fact he was (past tense) a great English novelist and to my
knowledge was not an astronomer.

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Did anyone else catch the lunar occultation of beta CAP Sunday evening?

See you at the meeting,

Russell Whigham