Geologists ID Asteroid, Assess Mars

Researchers who gathered at the planetary geology session at the Geological Society of America's annual meeting in Boston in November had been looking as much to the skies as at the ground beneath their feet.

By investigating the 1- and 2-µm silicate absorption features in the near-IR spectrum of 1929 Kollaa, a team from NASA's Johnson Space Center, the University of North Dakota and Rensselaer Polytechnic Institute has deduced that the asteroid is a piece of 4 Vesta. The researchers used NASA's 3-m Infrared Telescope Facility atop Mauna Kea in Hawaii to make their observations.

The laser altimeter aboard the Mars Global Surveyor has produced exceedingly accurate topographic maps of the planet since it began collecting data in 1999. Researchers at Goddard Space Flight Center and at South River High School in Edgewater, Md., have reviewed the altimetry data that reveal >50-km-diameter quasicircular depressions in the northern lowlands. They report that the depressions are ancient, buried impact craters, indicating that the martian crustal dichotomy formed early and quickly.