Re: Lunar prospector "hard landing" observing opportunity

James Husnay Sr. (jhusnay@scsinet.com)
Sat, 24 Jul 1999 07:27:06 -0400

Philip Chien wrote:

>  Unfortunately 5:52 am EDT is a bit light for me, but I suppose it's certainly
> worth looking - after all
> few predicted ahead of time that Shoemaker-Levy-9 would make such a "splash" at
> Jupiter!

This will be a bit early for me too and a bit off topic. But I hope I can bring up
a couple of  interesting points concerning Philip's thought. It appears there
looking for the plume and not the impact and at this point of time a larger scope
might be needed? During the Jupiter Impact my son and I saw the first 2 impacts in
full blown twilight just after sunset in a small 4 1/2 reflector. In fact CNN's
John Holliman (now deceased) said, "It's even been reported that the 1st 2 impacts
have been seen by 2 amateur astronomers in Syracuse, NY.",  after we reported it to
the local media which apparently then pooled the info.

(Jupiter was a pretty small disc in twilight and the resolution of the impacts
where better at lower power - - - can a larger disc with a small scope and a higher
powered wide angled lens do it again????.)

So Philip I agree and am going to presume there' a possibility for anything as
sunrise for my local is at 05:54 - 2 minutes after scheduled impact - I have a
large hill behind and to my east which shadows and have observed the moon in
morning twilight to the west on many occasions. I think the moons elevation will be
the key for us. Two things for certain I will envy those out west and hope for
clear sky's. I also will be pausing for a moment for this reason.

This was in my mail on Thursday as a bulletin and since I haven't seen it posted I
hope the seesat members won't mind as this is an important event for all of us. If
it wasn't for another impact many of us would never have gotten to know Carolyn and
Eugene Shoemaker, along with David Levy as we have and for those of us who look-up
each night at the wonders have become better for it, so it might be worth taking a
look up at the moon on the 30th or 31st if it's just for a free moment. It appears
the moon is going to be memorialized again, it's my understanding the crater being
impacted is presently nameless, does anyone know if they've already named a crater
after Gene Shoemaker?

Subject: Lunar Prospector Impact
Date: Thu, 22 Jul 1999 17:14:28 -0700 (MST)

LUNAR PROSPECTOR
IMPACT
OBSERVING BULLETIN

The Lunar Prospector has been orbiting around the Moon for nearly 18 months
being credited for many new discoveries about our Moon. Its time has come to
an end with its fuel nearly exhausted. It was decided to attempt to crash the
spacecraft in one of the ice filled craters instead of allowing the
spacecraft to crash into the Moon uncontrolled. I had not given it much
thought as to being able to detect the impact plume with our equipment until
Kyle Davidson, the science editor for the San Francisco Examiner, called me.
He asked if I was planning to have the LTP team monitor the South pole for a
possible impact plum that may be visible over the crater rim. Upon calling
Dr. Alan Binder and reading the information on the Lunar Prospector Web page,
I came to the conclusion that we may in fact be able to see something against
the back drop of black space.

The impact is going to be monitored by the Hubble Space Telescope, McDonald
Observatory at Austin Texas, Keck Telescope in Hawaii. and the Submillimeter
Wave Astronomy Satellite.

 What will happen is the Lunar Prospector will be sent into a high orbit as
it tracks around the Moon from south to north It will climb into a 200
kilometer maximum altitude  orbit and when it swings around the back side
will reappear over the South pole for a few seconds before impacting into the
40 kilometer wide by 4 kilometer deep unnamed crater located at  87.7 S. Lat.
by  44.0 E. long The impact will take place at 9:51 U.T. 31 July 1999 or 2:51
A.M. Pacific Daylight Time. They are expecting a debris plume of lunar soil
to clear the wall of the crater and may be detected by large telescopes in
the visible range.  They are expecting up to 18 kg of water ice could be
ejected and vaporized by the impact. This vapor plume should be detectable by
infrared instruments.

The key will be to observe at the maximum magnification that seeing will
allow. If any thing can be seen it's apparent that a large instrument may be
needed. I remember when the comet fragment struck Jupiter in 1994.  The word
was we would not be able to see the impacts on Jupiter.  I was blessed with
an amazing 14 hours of observations, following that statement by watching
black smudges appear on the face of the Jupiter.

There will be many challenges to seeing the debris plume since its size will
most likely be small.  Also depending where your are located, the sky will
start lighting up with the coming dawn, reducing the chances of seeing the
plume against the black back ground of the night sky. This may be another one
of those rare moments in life when the unexpected happens giving us the gift
of wonder and amazement to carry with us for all time.

Also I think it would be fitting to have a moment of silence for Dr. Eugene
Shoemaker, a planetary scientist who was instrumental in the training of the
Apollo astronauts.  He was also a strong supporter of the impact theory for
the cratering seen on the Moon and other worlds to include the earth.  He was
also the principle investigator for the Clementine mission.  This gave me the
opportunity to work with him to coordinate the ground based observers.  When
the Lunar Prospector crashes into the Moon, one ounce of his ashes will rest
on the Moon for the rest of eternity.

Also there may be last minute changes so I recommend that you check in on the
Lunar Prospector Web site and check the impact section at,
http://lunar.arc.nasa.gov/
Remember to let us know if you see anything.

Good Hunting.

David O. Darling
A. L. P. O.  Lunar Transient Phenomena Recorder