By Sid Perkins
From San Francisco, at a meeting of the American Geophysical Union
Using data gathered by a satellite launched almost 3 years ago, scientists have assembled the most comprehensive high-resolution map of Antarctica that’s ever been made.
The laser altimeter onboard NASA’s ICESat orbiter fires pulses of light down at Earth more than 40 times each second, says John P. DiMarzio, an engineer at NASA’s Goddard Space Flight Center in Greenbelt, Md. The pulses, about 70 meters across when they reach the Earth’s surface, reflect back toward the spacecraft. The time that each pulse takes to make that round trip reveals the elevation of the spot it hit.