Scientists have eyes on the moon

By TODD NEFF
Scripps Howard News Service
Tuesday, June 05, 2007

The moon peaked as a scientific focus soon after the Apollo 17 lander lifted the last men from its surface 35 years ago.

Yet as NASA's Constellation program gears up to spend billions of dollars to return people to the moon, scientists are thinking hard about how to share the wealth -- and leverage Luna for science as well as exploration.

Following the mission money is nothing new in space science, said Bill Bottke, a planetary scientist with the Southwest Research Institute in Boulder.

"People go where the data is," Bottke said, and data comes from expensive space instruments on manned or unmanned missions.

Bottke and fellow Southwest Research Institute scientist Hal Levison use computer models to simulate such things as the solar system's creation and the behavior of asteroid belts. For them, new data from the moon will help set hard limits for their equations.

"We can do a lot of guessing on our computers, but we need constraints," Bottke said.

Bottke said more thorough sampling of moon rock could help scientists determine how the moon stratified into different layers as it cooled from a molten ball. Such understanding would shed light on Earth's own evolution, Bottke says.

The moon also serves as what Bottke called a "witness plate" to 4.5 billion years of solar-system history, which is of particular interest to Levison.

Levison and colleagues developed a model that suggests the solar system's planets migrated from entirely different orbits, triggering a hailstorm of asteroids or comets known as the Late Heavy Bombardment about 4 billion years ago. Many of the moon's craters could date from that era.

"Studying the moon will allow us to actually look at the impact rates over time, which really will allow us to study planetary evolution," Levison said.

On Earth, geologic activity has long since buried evidence of such bombardment. Apollo missions brought home a lot of rock, but the six landings happened on relatively new surfaces, Bottke said.

Lunar sampling and subsequent dating of craters could help date the event -- or perhaps even disprove it and send Levison and colleagues back to their keyboards.

Jeff Taylor, a research professor with the University of Hawaii's Hawaii Institute of Geophysics and Planetology, helped lead a recent workshop on science and lunar exploration in Tucson, Ariz.

Among the ideas advanced were using the moon as a base to study Earth from afar and investigating the history of solar radiation by looking at how it changed moon rocks over time.

"In principle, you can research the past history of the sun by looking at the moon," Taylor said.

Taylor said University of Colorado astronomer Jack Burns has advanced the idea of building radio-astronomy observatories on the far side of the moon. The moon itself would shield low-frequency radio telescopes from Earth's own radio noise.

Taylor said more lunar sampling could also refine Southwest Research Institute scientist Robin Canup's widely accepted model of a Mars-sized body smashing the proto-Earth to create the Earth-moon system roughly 4.5 billion years ago.

"It could give us the composition of the projectile, which may tell us where it came from," Taylor said.

(Contact Camera Todd Neff at 303-473-1327 or nefft(at)dailycamera.com.)