Space shuttle astronauts deployed the longest rigid structure ever built in space today and continued work to check out the equipment they will use to produce unrivaled three-dimensional images of the Earthís surface.

Red Team leader Commander Kevin Kregel, and colleagues Janet Kavandi and Gerhardt Thiele initiated extension of the radar mast at 5:27 p.m. CST. After 17 minutes, all 87 cube-shaped bays of the carbon fiber-reinforced plastic, stainless steel, alpha titanium, and Invar structure were deployed by 5:44 p.m. Total length of the mast was 60.95 meters, or just under 200 feet.

The crew also maneuvered the shuttle into the proper attitude, or orientation, for mapping. This orientation points the shuttle payload bay ñ and its inboard and outboard radar antennas ñ at the Earth. Endeavourís tail is leading the way as the shuttle orbits about 150 statute miles above the surface. The Red Team then began a series of jet thruster firings to test the ability of dampers to absorb the force of planned maneuvering jet firings and keep the inboard and outboard antennas properly aligned. This alignment is crucial for scientists who will need to combine the radar images received by the two sets of antennas.

The Shuttle Radar Topography Mission will record radar data in both C-band and X-band radar wavelengths. This data eventually will be processed into 3-D maps of the Earth that are 30 times more exact that those currently available. These maps will be important to scientists in many disciplines, ranging from ecology to geology to hydrology, as well as a number of military and commercial applications.

As the Red Team performed the checkout procedures, Blue Team members Dom Gorie, Janice Voss and Mamoru Mohri set up the shuttleís network of portable computers and began an abbreviated six-hour sleep period at 3:44 p.m. Theyíll be awakened at 9:44 p.m to begin radar mapping operations late tonight.

Endeavour is orbiting the Earth in an orbit inclined 57 degrees to either side of the Equator for the radar mapping of a majority of the Earthís surface. The shuttle completes one orbit every 90 minutes at an altitude of about 150 statute miles.