The American Geophysical Union comes to San Francisco every Yuletide. I've attended the AGU's annual Fall Meeting, first as a passionate bystander and later as a member of the press, since the mid-1980s. In 2000 I kept this diary. The meeting space at the Moscone Center is mostly underground, but the rooms are big and airy. Some 9,000 scientists showed up to present 7,800 talks and posters.
I spent the morning at a session in honor of the late William Kaula, someone I knew only as an eminent presence at AGU meetings. I usually saw him speak on the structure of Venus, but it became clear today that he was respected for much more. In 1966 his little book Theory of Satellite Geodesy became the foundation of a field: the ways we analyze the spacecraft motions to study the internal structure of the planets and asteroids. Asteroid 5485 is named for him.
One former student recalled asking in the early 1960s how he could even think of contributing to planetary physics, a field whose pioneers included Newton, Laplace, and so many other giants. Kaula's reply was typical: "You have a computer and they didn't."
Adrian Lenardic spoke about being Kaula's graduate student. Kaula told him, "Graduate students are like an investment—you shouldn't expect any return from them for two years." The two years Kaula gave Lenardic to ground himself in his field—and basically, he admitted, to get his head together—turned him into a focused, productive scientist. "When I was Bill Kaula's last graduate student, he was at his peak. Not just as a brilliant scientific mind, but as a teacher of graduate students," Lenardic said.
Other speakers had anecdotes to share as they surveyed the fields where Kaula led the way—the origin of the Moon, the inner planets, and comets. His widow shared more reminiscences, and JPL's Jean Dickey announced that Kaula's papers, archived at UCLA, will be placed on the Web.
Lunchtime! Restaurants nearby were jammed. The guy at the next table was talking about ozone, Mario Molina, electron transfer—another geophysicist. I saw the AGU program guide in his briefcase. On the train ride home another stood next to me: "We did those analyses for him in 1996, but they still haven't been published . . ." The whole town was alive with science.
The afternoon session I chose to attend was in the same room as the morning program. Unlike the intimate Kaula tribute, "Water on Mars I" packed the hall. I figured the recent paper in Science showing images of sedimentary rocks on Mars would rouse interest, and sure enough the paper's main author, Kenneth Edgett, was there to speak. His talk came last.
First Michael Carr tried to summarize the case for widespread water on Mars. Unfortunately he had prepared a 25-minute talk but had only 15! Anyway, the subject is full of ferment right now as people hunt for plausible ways to produce liquid water on this cold planet in the distant past. And then once the water is created, where does it go? Because today Mars is very dry. The next several speakers proposed scenarios that might account for it.
But Ken Edgett poured cold water on the group with his report of recent close-up images of the supposed shoreline of the northern Mars ocean. He took published papers that proposed specific places where shoreline features seemed to be. He and M. C. Malin pointed the Mars Orbiter Camera to those spots and found nothing—no sand bars, wave-cut benches and the like. He told the crowd, "We looked for the evidence, but it ain't there."
Of course, people jumped up and discussed it vigorously, but he held firm. And his unstated main point is that science progresses by making definite hypotheses and testing them, and the first round of simple tests have failed. And when it comes to spending the public money to fund studies of other planets, we need to have testable hypotheses. It was a bracing bit of scientific theater, pulling the speculation down to earth.
The afternoon ended with the Cesare Emiliani Lecture, given by James Kennett, on the "Clathrate Gun Hypothesis." That's his notion that eruptions of methane hydrates beneath the cold seafloor, sending the greenhouse gas methane into the atmosphere, causes the abrupt climate changes of the most recent ice age. Methane hydrates are solid compounds (clathrates) of methane gas mixed with ice under pressure. Enormous quantities underlie much of the seafloor and the Arctic permafrost regions. Kennett holds that when ocean warming triggers a collapse of the delicate hydrates, a feedback cycle shoots the world from frozen to balmy within the span of a human lifetime. It was a thorough exploration of this theory by a master of the field.
