The Buildup
I first met David Levy before he had discovered any comets (his latest
count is too high for anyone to remember). I remember being seated around
a breakfast table with him at a Riverside Telescope Makers Conference.
He appeared to be quite shy and said little. There was nothing about him
which foretold his incredible destiny. Eugene Shoemaker was a hero of sorts
for me when I was young, during the Apollo era. I wanted to move to Flagstaff
and follow in his footsteps, working at Meteor Crater and Lowell Observatory.
Shoemaker always seemed destined for big things. The discovery by Shoemaker,
his wife, and Levy of a broken comet in orbit around Jupiter was strange
enough, but when it became apparent that the 21 fragments would impact
the planet I couldn't believe it for a while. At first I had visions of
huge impacts visible to the naked eye. I thought of the black spot in the
movie 2010 which "ate" Jupiter, igniting the planet into a second
sun. I wondered if the long standing features on Jupiter such as the red
spot might have formed from impacts. I thought of the coincidence with
the 25th anniversary of Apollo 11, and wondered more than once whether
someone was sending us a birthday present. But then reality struck, as
the visibility the predictions became more gloomy. It appeared we would
probably see nothing after all. Due to a heavy work schedule I shelved
plans to rebuild and re-aluminize my 12.5" f/6 - why bother?
Mt. Wilson Excursion
Southern California was to have three opportunities to observe fragment
impacts. The first of these was to occur on Saturday the 16th just prior
to sunset. I had originally planned to observe at Highridge park, but when
I found a way to join a group observing with the 100" telescope on
Mt. Wilson, I felt I could not pass up the opportunity. I felt it might
take that much aperture to see anything, and good CCD imagery in near infrared
might show things undetectable in the visible. In addition, the Hooker
telescope was another of my childhood heroes, and I had never had a chance
to see the instrument. The 100" was just coming out of a mothball
sleep of several years, and the impacts were to be its first good workout
after refurbishing. Mt. Wilson has some of the best observing conditions
on the planet. I just had to be there. My wife Nina and I arrived early
to browse the grounds and sit in on the pre-impact talks. Several other
club members (Jim Tobin, Paul Harris and family, Mike Mayerchak, and Alan
Gayda) had arrived even earlier to take the guided tour of the observatories
(they raved about the tour, it is offered every week). In the course of
the evening we ran across at least a half dozen other members. In the early
afternoon we heard the first reports of the A impact from some of the professionals
on the mountain. Word was that South Africa saw a plume. Things were getting
exciting! The talks were excellent. First, Don Yeomans of JPL gave a full
report on the history of the comet and the predictions for the impacts.
He showed some outstanding simulations (good enough they should sell frames
of it on T-shirts). Next Robert Jastrow, another childhood hero, (remember
"Red Giants and White Dwarfs"?) spoke on how the impacts might
churn up organic molecules, or even organisms. His talk was awe inspiring
because it made one realize the magnificence of the events. As sunset approached
we gathered around a monitor to watch images from the 100". Here we
met our first disappointment. The CCD selected was simply a color video
chip, with contrast too low for this kind of work. In addition, working
in the visible, with no filtration, they could not expose the array to
light until nearly a half hour after impact! Intermittent high clouds and
turbulence interfered as well. Then a rumor circulated that someone had
inadvertently opened the dome during the afternoon and thrown the primary
mirror out of thermal balance. There is a standing joke among several of
the club members that CCD images are all playbacks or fakes, since none
of us has ever seen even one good image captured while we were watching.
We looked at each other and shrugged our shoulders one more time. Bets
were started regarding whether we would see anything at all. We started
wondering whether we would be better off in the parking lot where some
amateur scopes were set up. Finally an image was achieved, but there was
nothing to be seen out of the ordinary Strike one. Later we would learn
that fragment B turned out to be a dud, and the remains of A had rotated
behind the planet. We took some photos of city lights and looked through
a Meade 16" in the parking lot before leaving about 10 PM (to be home
for the midnight impact of C - there might be something on TV!). All of
us observers had completely given up on seeing anything from the impacts,
figuring it would take a monster telescope working in IR to play in this
game.
Discovery
On Sunday Internet downloads showed that this was a big show! But only
in infrared. Oh Well. The most impressive shots were from the Keck telescope.
These were personally inspiring, since Nina and I had been privileged to
see the telescope under construction on Mauna Kea in 1989. We wondered
then what new discoveries it would make (and this was not something that
occurred to us!). At a Chinese dinner that afternoon Nina got a fortune
which read "There is a prospect of a thrilling time ahead for you".
We hoped it meant something about the comet, but soon forgot about the
fortune. In the evening I decided, just on a whim, to try out my Celestron
3.1 " refractor with a 4.8mm Nagler purchased some time back (and
woefully under-used). I wondered just how good the images with the new
eyepiece might be, and how the little telescope would stack up against
the 100" imagery. The sun had just set, and the sky was still bright
when I found Jupiter and brought the scope to bear. My first words were,
"My god, that's an impact sight!!!". What I saw was the most
distinctive feature on the face of the planet. It looked like nothing else
I had ever seen (except for a satellite shadow, which I quickly eliminated
from consideration). I wondered if it might be a natural feature I didn't
remember. My planetary observing was a bit rusty. However, I could not
remember this kind of feature at this high latitude in my nearly 30 years
of observing Jupiter. In addition, this black spot had a halo around it!
As I watched for a few minutes I found there were two black spots separated
by about 30 degrees in longitude, and they both had haloes. I got on the
phone and started an impromptu calling tree of most of our dedicated observers.
Soon we were exchanging excited phone calls and comparing details. Two
things became apparent quickly. First, there was a third black spot which
had risen over the eastern limb of the planet. Second, it looked like my
house, on the lee side of the peninsula, had the best weather. We made
plans to meet at my house on the evening of the 20th to celebrate Apollo
11 and watch impact R. I went back to the scope and made some sketches
(my little 3.1 is on an alt-azimuth mount, the C-8 in the garage actually
gives poorer images, and the 12.5" was still in mothballs, so I had
no photographically capable instruments). That first spot had to be from
the most recent impact that afternoon but, while it was at about the right
latitude, it appeared off in longitude. Then I remembered something on
Internet about how the impact features were lagging behind the normal planetary
rotation rate. Hmmm. As I went to bed I still wondered if these were not
just regular features and I had just been carried away with the excitement.
After all, we had no reason to think there would be any features discernible
in small telescopes. We had seen no visible light images showing such features
from any observatory. I did not sleep well.
The Morning After
On Monday morning I turned on the TV. After a few channels of the usual
TV wasteland I stumbled across a near UV (that's nearly visible) image
from Hubble, and there they were - the three black spots! I spent much
of the day at work pointing out that I am the only guy I've ever heard
of who made a discovery with a 3" refractor which had to be confirmed
with the Hubble Space Telescope! That night I observed more impact sites.
The impact site of fragment H was spectacular as it came around the eastern
limb. With the dust clouds on the limb I was looking through the maximum
path length and the scar appeared to take a bite out of the planet. It
reminded me of the appearance of a solar eclipse a few minutes after first
contact, but the edge of the bite was straight. A better description is
that it looked like Jupiter had been dropped and dented. As the impact
scar rotated into view it looked smaller but it still looked nearly twice
the size of Ganymede! That's about the size of the Earth. On Tuesday I
attended an Apollo 11 observance where I work. My company (TRW) built the
Lunar Module Descent Engine, the Lunar Module Abort Guidance System, and
developed many of the Apollo mission requirements. That was back when I
was a kid, and those events inspired me to pursue the career path I chose
(ultimately developing mission requirements for future space systems).
It was great to have the opportunity to hear from the guys who made it
happen. One fellow told me he had been sent to the Cape in the last three
weeks before the launch to determine just when the descent engine tanks
would run dry. He said he had his own timer running during the landing,
and he figured Armstrong had already run out of fuel a couple of hundred
feet off the surface!
A Big Splash for the Anniversary
On Wednesday night a large crowd gathered in my front lawn in San Pedro
with an 18" newtonian, C-8, 5" refractor, 4" refractor,
and my trusty little 3.1". My neighbors were a bit overwhelmed, but
they all got a chance to see the impact spots, and seemed pretty happy
with their choice of neighbor. Seeing varied from mediocre to excellent,
and at the best we thought we could see eleven individual impact scars.
We set up a TV near the snack table for Apollo 11 programs, and the PBS
special on the impacts. The shy David Levy was now wearing a tuxedo on
national TV! I'm sure his friends will not let him live it down at next
year's RTMC, since each year there is a prize awarded for "overdressing
at the conference". As the time for impact R approached we manned
each eyepiece with our most experienced observers, hoping to see evidence
of the fireball peeking around the limb. At R minus four minutes a cloud
deck moved in, and that was that. I muttered something to Nina about not
blowing thousands of dollars on a solar eclipse expedition in November,
since I felt I could predict similar results). We consoled ourselves with
TV and looking at meteorite samples. Three of us present were meteorite
collectors, and we had a couple of samples of what may be comet nucleus
material (types Cl and CM2). It was pretty heady stuff to hold a piece
of a comet in your hands and look at what was going on at Jupiter. Later
we found out that impact R was spectacular, and apparently Hawaiian observers
did see the fireball. Strike two.
Last Chance
The last opportunity to see an impact was with fragment V on the following
night. Most of the same crowd gathered again, and some new neighbors introduced
themselves. We manned the eyepieces once again with our most seasoned observers.
We watched from before the earliest predictions to well after the last
ones, and saw .... nothing. Maybe you did need infrared to see fireballs.
We later learned that V was another dud. Strike three. But Wait
--------
As I write this note it is Thursday night the 29th (30 July in UTC).
It is a full week after the last impact now, and most people have not given
Jupiter a second look. Ha! The biggest surprise was yet to be. I am looking
tonight at two enormous impact scars, each from multiple impacts. Each
one is several times bigger than the Earth. That's right, they're GROWING.
I can see at least eight of the original impact spots, and they don't seem
to be dissipating much. I'm starting to think about 2010 again. When in
the movie Dave is asked what is going to happen, his response is "something
wonderful". I am here to tell you, this is something wonderful. The
entire south polar region is becoming hazy with what may be high altitude
comet dust. Most amazing of all, my suspicion about the impacts creating
new long-lived features may prove to be correct. The two largest scars
are growing in longitude and threaten to grow together, perhaps starting
a new planetary belt. All of the impacts are at roughly the same latitude,
and thus may all participate in belt formation. If this turns out to be
one way in which belts form, and if the only way all impacts can occur
in the same latitude is for the comet to be broken up and orbiting Jupiter
...... well there are a lot of belts on Jupiter. I wonder if these events
are so rare after all. Maybe someone is trying to tell us something.
Aftermath
These have been two of the most exciting weeks of my life. I have been
on an emotional roller coaster with each new image and view. In this note
I have barely scratched the surface. I never mentioned my (unsuccessful)
attempts at monitoring decameter radiation from the impacts, or the many
other fantastic effects observed from the major observatories. I have had
some feelings of sadness mixed with the excitement. Jupiter may never be
the same familiar friend. But in my old age I may be able to tell youngsters
I remember Jupiter before the impacts. On the Sunday after the impacts
I watched archival TV footage of the original live coverage of Apollo 11,
and saw a slightly more youthful Shoemaker walking around Meteor Crater
speaking of impacts, and a visionary, romantic Jastrow speaking of how
the astronauts might find organic matter, or even life on the lunar surface.
Tonight I heard about the possible detection of "strange" organic
molecules in the Jovian impact plumes. Everyone has dreams. Some come true.
