MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011

PHOTO CAPTION P-49954AC
July 8, 1998

This is a view of the Shuttle Radar Topography Mission mast after it has been 
fully extended during tests at AEC-Able Engineering Company, Inc., the mast
subcontractor.  In the foreground is the triangular tip-plate on which the
outboard radar antennas will be mounted.  Behind the tip plate is the 
"milk-stool", a three-legged support which will allow coarse mechanical 
adjustment of the antenna alignment once SRTM is on-orbit.  Note the white 
ribbon cables in the box-like mast structure and the suspension wires hanging
above the mast, which are needed to compensate for the mast's weight on earth.
The box structure surrounding the mast in the background is a thermal test 
chamber.

Set for launch on the space shuttle in September 1999, the Shuttle Radar 
Topography Mission is designed to collect three-dimensional images of nearly 80 
percent of the Earth's land surface, except near the poles, with a resolution of
30 meters (98 feet).  To collect the 3-D data, engineers will add the 60-meter-
long (200-foot) mast, additional radar antenna, and improved navigation devices 
to the original Spaceborne Imaging Radar-C hardware, which flew twice on the 
shuttle in 1994. The mission is a cooperative project between NASA and the 
National Imagery and Mapping Agency (NIMA) of the U.S. Department of Defense, 
and is managed by the Jet Propulsion Laboratory for NASA's Earth Science 
Enterprise.