The popular event today was the sunken cities of Egypt I mentioned yesterday. But I went to see a handful of star scientists talk about the deep interior of planets. Raymond Jeanloz, whose talks I seek out, opened the session by surveying the methods we use to observe actual materials at the conditions of the deep Earth. These include the diamond-anvil cell, which not only can compress samples but laser-heat them as well. And there are the remarkable explosive shock-wave techniques that can reproduce the conditions deep inside the major planets—for about a microsecond—before they destroy the entire apparatus.
But a new technique delivers shock waves to samples within the diamond-anvil cell using lasers. "They yield phenomenal data that have really rocked the field," Jeanloz said. We can reproduce conditions that previously could only be reached, he said, during underground nuclear tests, "techniques that thankfully we are no longer allowed to use."
Other speakers included Adam Dziewonski, pioneer of seismic mantle tomography, who surveyed the state of our mantle models. David Mao told how novel techniques are giving us data about many of iron's physical parameters, and Michael Brown described laser techniques to extract data about the shear behavior of iron at high pressure.
And the wide-ranging David Stevenson spoke here too, about Earth's core and why it has more energy than it should. His hypothesis is that when Earth was forming, major impacts delivered large bodies of iron to the core whereas most of the core's iron percolated down slowly, like droplets of water through oil, in small bodies. While small bodies left their energy in the mantle, the large ones gave it directly to the core, which allowed the geomagnetic dynamo to start immediately. Such a process, he added, would work to a lesser extent on Mars (which indeed was slow to have a geodynamo) and not at all on the Moon, even though all three bodies got plenty of impacts.
It was time to wander through the posters again. Here were some highlights:
- The sun's variability has influenced Earth's climate both directly and indirectly during the last century.
- The [International Crown Fire Modeling Experiment has burned forests for science for the last four years.
- The "weight of the seasons"—changes in groundwater and snowfall that raise and lower the crust by several millimeters during the year—can be predicted from weather data and used to correct satellite geodetic measurements.
- Pseudonumerology is an amazing way to memorize data that everyone should learn, says Professor Krill.
- USGS scientists entertained AND educated the public with a surprisingly realistic model of Los Angeles faults made of foam rubber and wax paper.
- Former science bureaucrat Peter Wilkniss (polarki@aol.com) is trying to bring whole science and whole Earth thinking together for Alaskan schools in the context of global warming—as he puts it, "Arctic realities, dreams of consilience."
- Kiyoyuki Kisimoto wants everyone to visualize a global topographic database in 3D—don't forget your red-blue glasses!
- Some folks drilled holes in stones, fitted them with radio transmitters, and followed them down a rocky streambed.
- Amazing map images of seafloors (and Crater Lake and Lake Tahoe) are up on the USGS Web site.
- The lake in the Bosumtwi impact crater has been cored.
My afternoon delight was a session on "Planetary Atmospheric Processes and Astrobiology," run by Frank Drake of the SETI Institute and David Morrison of NASA-Ames Research Center. Two talks at the end went into the sexy questions—if life can exist on Mars, where would it live and how could we detect it? The consensus seemed to be that any bugs would be much like the Archaea microorganisms that live deep underground. There is enough of what they eat in the martian air (carbon monoxide, hydrogen gas, and in some cases oxygen) so that they could survive. Tim Kral is incubating some of these critters in sterilized soil under martian conditions with some success.
I quickly headed out of the hall, eager to get home a little early for once, and paused to ride the escalator. As I rose up the human waterfall I spied the father of plate tectonics, Jason Morgan, wandering alone near the base of the stairs, a faint smile on his face. I imagine that he has many moments of quiet satisfaction as he looks around the Fall Meeting these days, a generation after his scientific breakthrough.
