It all started with some black dots in a space image. The satellite Dynamics Explorer 1 was launched in 1981 to look at Earth in far ultraviolet light. The pictures it sent down were thrilling—the whole Earth glowed at these wavelengths, the daylit side shining softly in the far-UV light of excited oxygen atoms, the poles crowned with beautiful haloes corresponding to the aurora.
The scientist in charge of the instrument, Prof. Louis A. Frank of the University of Iowa, set one of his physics undergraduate students to work on the images, but John Sigwarth was hampered by black spots. Maybe they were just glitches, camera noise or data transmission errors or something else that could be safely ignored. "But you cannot alter data on a mere assumption," Frank later wrote. "You have to have a reason."
After nearly a year of intense effort, Sigwarth and Frank and John Craven (who built Explorer's instrument) concluded that the black spots were something real out in space. They must be caused by the disintegration of comets, small ones weighing a few tons, the size of a large house. They must be made of water, and there must be thousands of them a day. They must be too small and too fast and too far away to see from the ground. Frank recounts the story in garment-rending detail in this book excerpt.
Their work was published in the April 1986 issue of Geophysical Research Letters, known in the trade as GRL. Rarely does a scientific discovery produce the controversy that erupted. During the ensuing year, 11 separate formal Comments were published and the three authors prepared 10 formal Responses. Finally the editor of GRL, Alex Dessler, wrote that "there is a limit to the number of Comments that will be accepted on even the most controversial of Letters."
This scientific flamewar is an example of the refiner's fire of debate that any new idea must face. It strengthened Frank's convictions. In 1990 he published a trade book that, like some 17th-century classic, laid out the whole scope of his thoughts in its title: "The Big Splash: A scientific discovery that revolutionizes the way we view the origin of life, the water we drink, the death of the dinosaurs, the creation of the oceans, the nature of the cosmos, and the very future of the earth itself."
The most thorough treatment of the ice-comet hypothesis is in Reviews of Geophysics, in two articles, the first (August 1991) by Dessler, who had published Frank's GRL article, attacking the theory ferociously, and the second (February 1993) by Frank and Sigwarth responding to each point in what seems like a sensible way. It and all their other articles are available online from the University of Iowa.
In 1999 the two researchers went on to publish evidence from a camera on NASA's Polar satellite, showing more holes. A team in Berkeley argued that the spots in the Polar images arose from the way Frank had erased bright speckles due to space radiation in the camera. Frank has not refuted that argument, as far as I can tell. In 2000 Robert Mutel, a fellow physics professor at Iowa, reported that a telescopic search from the ground had come up empty. Frank then took Mutel's images and found some very faint streaks in them, dimmer than Mutel had looked for. They are so dim that it's hard to credit them as real.
I honestly don't know what to make of it. Some problems in science remain indeterminate for a long time. But two very powerful things are evident in this story. First is the human fury that a disruptive idea arouses. Frank has described the wounds to his career and the contempt and shunning he has felt from his peers—even though he continues to publish respected research in other aspects of geophysics.
Frank's theory shows how people deal with a major scientific controversy. Dessler concluded his critique in Reviews of Geophysics with some understated highhandedness: "It seems unlikely that the scientific community will expend much additional effort in investigating either the small-comet hypothesis or its consequences." He will live that down if he's wrong—every scientist is wrong sometimes. But he didn't have to say it.
Nor could Dessler resist a further patronizing dig. "If small comets exist, their presence would be confirmed in due course. If [Frank and coauthors] were correct, they would enjoy fame and glory; nothing their critics said would be remembered, except perhaps as quotations demonstrating the evils of scientific dogmatism." Never mind that posterity "in due course" is small comfort when you feel personally attacked by your peers.
The second thing is the temptation to pursue a beautiful theory because of the answers it promises. More on that next.
