Twin probes will map Earth's gravity
(CNN) -- NASA and the German Space Agency are preparing to launch two satellites into orbit on Sunday on a five-year mission to study Earth's gravity field.
The Gravity Recovery and Climate Experiment, or GRACE, aims to map variations in the Earth's gravity field as it changes over time in response to shifts in sea levels, the ebb and flow of glaciers, the seasonal melting and freezing of ice sheets, and other such fluctuations.
The twin satellites -- which had been scheduled to launch on Saturday but were delayed by bad weather -- will fly in tandem about 137 miles (220 km) apart, circling the Earth 16 times a day. Subtle variations in Earth's gravity field will cause tiny shifts in the distance between the two as they orbit.
The satellites' measurements of the distance between the two will be combined with data from the Global Positioning System, allowing scientists on the ground to assemble a composite map of the gravity field.
NASA said that map will help researchers create precise digital global terrain models for use by geologists, oceanographers, hydrologists and glacial scientists.
The maps will also be useful to scientists who study global climate change.
The satellites will be launched together aboard a single rocket from Plesetsk, Russia.
NASA satellite pair to tackle weighty task
January 1, 2002
Note: Pages will open in a new browser window
External sites are not endorsed by CNN Interactive.
SPACE TOP STORIES:
NASA starts countdown to Mars mission
Shuttle probe could take six months
Shuttle widows grasp faith, each other
EPA approves new modified corn
Mexico saves island from tourism build-up
|Back to the top|