Obituary: Eugene Shoemaker

Before the lecturer had so much as uttered a word, a slide went up portraying a spectacular group of assorted dinosaurs, writes Tam Dalyell. The scene was the George Street lecture hall of the Royal Society of Edinburgh on 21 February. The distinguished audience derived mainly from Edinburgh's three universities, and the British Geological Survey. After a pause, Eugene Shoemaker said with a twinkle, "Comets and astronauts - they are the reason why we are here, and our dinosaur friends are not!"

For the next couple of hours Shoemaker riveted academic, scientific and not easily impressed Scotland. We learnt that there are a million objects in the universe like the one that flattened vast stretches of the Siberian forest: that it was a damn close run thing that Halley's Comet did not hit the Earth 1,000 odd years ago; that there was a near miss in 1770 by probably a matter of a mere 4.5m kilometres, astronomically a short distance. Chances of a 10mm-long comet hitting the Earth were one every 105,000 years, of a 20km-long comet one every 475,000 thousand years, of a 150km comet hitting the Earth one every 100 million years.

Whatever these figures, Shoemaker has been responsible for the resurgence of interest about the possible risk to Earth from Doomsday astronauts and wayward comets.

Over dinner in the Prestonfield House Hotel Shoemaker regaled Peter Cook, the Director of the Geological Survey, Geoffrey Bolton, Professor of Geology and DNA Science at Edinburgh University, and our wives with his dreams of being an astronaut himself, sadly unfulfilled by a medical condition.

Cook had first met Shoemaker in 1965 in Flagstaff, Arizona, the home of astrogeology. "I was deeply impressed at that time," says Cook, "by the quality of his science and his dedication, enthusiasm and charisma. These same personal qualities were critical in persuading the Nasa to make geology a major part of all its lunar and planetary programmes."

Eugene Shoemaker deserves to be remembered for far more than being immortalised by giving his name to the spectacular crash into Jupiter of Shoemaker-Levy.

Above all that night in Edinburgh proved that he was a magical stimulator of scientifically well- founded ideas.

Eugene Merle Shoemaker, geologist: born Los Angeles 28 April 1928; geologist, US Geological Survey 1948-93, Chief, Branch of Astrogeology 1961-66, Chief Scientist, Center of Astrogeology 1966-68; Acting Director, Nasa Manned Space Sciences Division 1963; Research Associate, California Institute of Technology 1964-68, Professor of Geology 1969-85; Principal Investigator, Geological field investigations in Apollo lunar landings 1965-70; married 1951 Carolyn Spellmann (one son, two daughters); died near Alice Springs, Australia 18 July 1997.