New satellite to measure ice sheets

By Andrew Bridges
Associated Press
Dec. 17, 2002

NASA scientists hope to get new insight into the future of global ocean levels with the launch this week of a laser-equipped satellite designed to measure the waxing and waning of the planet's largest ice sheets.

The Ice, Cloud and Land Elevation Satellite, or Icesat, is intended to spend a minimum of three years making non-stop measurements of the elevation of the ice sheets that blanket Greenland and Antarctica.

That will help answer the question of whether those layers of ice, which are up to two miles thick in places and contain an estimated 8 million cubic miles of fresh water, are growing or shrinking.

"Very simply, we do not know," said Jay Zwally, the mission's project scientist at NASA's Goddard Space Flight Center in Greenbelt, Md.

Icesat is scheduled for launch aboard a Delta II rocket on Thursday from Vandenberg Air Force Base on the central California coast. The question that the $282 million Icesat project is designed to answer is important: If more ice melts off the sheets than piles up as snow, the water would contribute to the already measurable rise in global sea levels. Scientists fear that rise could flood coastal regions and upset the ocean circulation patterns that play an important role in determining climate conditions.

Sea levels currently are rising about 0.8 of an inch every decade. About half of that rise is attributable to the melting of small glaciers and the warming of the oceans, which expand as temperatures rise.

The cause of the other half is unknown, although ice sheet melting is suspected.