Satellite Will Measure Thickness of Icecaps

A NASA satellite being launched Thursday to take precision laser readings of the world’s icecaps will yield the most accurate view yet of melting at the North and South poles.

Scientists have noticed melting in Greenland, the Arctic Ocean and parts of Antarctica. But some parts of Greenland and Antarctica are accumulating ice, leaving scientists unsure of what is causing the melting in different regions or how much that melting will raise sea levels.

“The time is really right to take a comprehensive look,” said Waleed Abdalati, a lead scientist of the new ICESat project. “Big things are going on.”

The satellite will use a laser altimeter system pulsing 40 times a second to measure the thickness of ice to an accuracy of about 5 inches, said scientist Jay Zwally, and it will focus on Greenland and Antarctica.

It will also be the first satellite to take precise measurements of clouds and atmospheric aerosols such as soot, sulfate and sea salt -- particles that play a large but little-understood role in governing climate.

The $232-million mission is scheduled to be launched from Vandenberg Air Force Base.