Friday, July 16, 2004


I know where I was 10 years ago today, without even trying to think about it. You see, my good friend David Levy along with one of the nicest ladies on the planet and her husband, a man who was one of the greatest scientists of the 20th century, discovered the shattered remains of a comet near the planet Jupiter 10 years and 16 months ago which the world knew as comet Shoemaker-Levy 9. I was in the right place at the right time when David called me from Mt. Palomar to help them confirm their new discovery on the night of March 26, 1993. It was one of the most exciting moments of my career, right up there with the discovery of my own comets and the announcement that one of my own discoveries might make a close approach to Earth 30 years later (which you might recognize as 1997 XF11) when I became the first person in the Universe to see their new comet for what it was as a string of broken pieces of comet (their faint fuzzy images only hinted at what I was able to see with my CCD camera on a telescope with about four times the light gathering power). So, 16 exciting months after their discovery, following meetings with colleagues who, along with me, were planning to try and observe and study the comets demise, the 21+ fragments plummeted into Jupiter over about 6 days in July 1994, beginning with the first fragment on July 16. I traveled to the Wise Observatory in the desert of Isreal where we were going to try to observe the affects of the first impact, of fragment "A". Jupiter was not very well placed in the western sky following sunset and the Moon approached Jupiter closely, but the longitude where the Wise Observatory is located was at the right place on planet Earth to be in the dark while Jupiter was still high enough to observe in the sky. I was part of a network of observers spread around the globe to try and observe as many of the impacts as possible. And that is why I remember where I was 10 years ago today.

It does not seem possible that it has been 10 years already. It is also hard to believe that it has been 7 years since one of the discoverers, Gene Shoemaker, was killed tragically in a car accident while studying impact craters in Australia. But this Geologist turned Astronomer lead a wonderful life, taking up the science of Geology as a young boy and turning his eyes towards the moon. If everything had worked his way, he might have been the first geologist to walk the Moon, but instead, it was one of his protoge's who took that honor, but after his death, he became the first to have his remains left on the moon when some of his ashes flew aboard the Lunar Prospector spacecraft which was deliberately crashed onto the moon at the end of its mission to map the minerology of the Moon. Gene Shoemaker studied Meteor Crater in northern Arizona and definitively proved that it was the result of the impact of a small asteroid. He later founded the Astrogeology branch of the United States Geological Society in Flagstaff Arizona and lead the first U.S. spacecraft to softland on the Moon during the Surveyor program as well as leading the geological investigation of the Moon during Apollo. After Apollo, he turned his eyes and brain towards the stars, realizing that the pulverized cratered surface of the Moon continues to be pounded, and he knew just what to do to learn first hand about the objects that continued to pound the Moon. Shoemaker and a few farsighted colleagues invented another field of research, the Near-Earth Asteroid (NEA) field by designing one of several innovative survey programs which pioneered the field of NEA discovery. It was as part of his survey that Gene and his wife Carolyn and David Levy stumbled upon one of the most momentous moments in history with their discovery of Shoemaker-Levy 9.

I find it even more interesting that the impact of Shoemaker-Levy 9 occured on the 25th anniversary of the flight of Apollo 11 - the first manned landing on another world and an event that Shoemaker himself was heavily involved in. The first impact on July 16 marked the 25th anniversary of the launch of the Apollo 11 Saturn V and today, I remember not only the wonderous impacts of S-L 9 on Jupiter 10 years ago, but the flight of the first men to walk on the moon 35 years ago, an event that inspired this then future scientist to learn more about the Moon, planets, stars and Universe.


Thursday, July 01, 2004


The Cassini spacecraft successfully made it into orbit around Saturn last night. It had to successfully pass through the ring plane of Saturn twice and fire its rocket engine for 96 minutes to change its velocity by 626 meters per second (about 1,400 miles per hour). I watched NASA TV during the event and waited along with more than a dozen friends and colleagues who have invested as many as 15 years working on Cassini. Each hurdle passed with the cheers of the folks on TV at the Jet Propulsion Lab (JPL) control center as we watched the Doppler velocity graph change as they tracked the spacecraft during its close approach to the planet and its rocket engine burn. After its engine shut down right on time, the largest cheers were heard. In the meantime, out at Saturn, the spacecraft turned its high gain antenna towards Earth to improve communication and then turned its powerful cameras onto the rings of Saturn as it made its closest and best approach of the entire 4 year orbital mission to the rings. This morning, it beamed its images back home and we've seen some of the fantastic images on the web and in the news. It is just the beginning of 4 wonderful years of discovery around the Solar System's 2nd largest planet.

Next up: a close flyby of Titan, the 2nd largest moon in the Solar System and the equivalent of your grandmothers freezer where she kept those Apple pies frozen and awaiting your visit, in this case, a frozen snapshot of planet formation in the early solar system. Titan is hidden by a thick cloud cover that keeps us from easily seeing the surface. In December, Cassini will release the Huygens probe which will enter the atmosphere of Titan on January 14 and parachute through its atmosphere taking measurements and images all the way to the surface. Will it land on solid ground or will it land in an ocean of methane? Some of my friends designed and built the camera that will show us.