NASA has extended its contract with the Smithsonian Astrophysical Observatory in Cambridge, Mass. to August 2003 to provide science and operational support for the Chandra X-ray Observatory, one of the world's most powerful tools to better understand the structure and evolution of the universe.

The contract is an 11-month period of performance extension to the Chandra X-ray Center contract, with an estimated value of $50.75 million. Total contract value is now $298.2 million. The contract extension resulted from the delay of the launch of the Chandra X-ray Observatory from August 1998 to July 1999. The revised period of performance will continue the contract through Aug. 31, 2003, which is 48 months beyond operational checkout of the observatory. The contract type is cost reimbursement with no fee.

The contract covers mission operations and data analysis, which includes both the observatory operations and the science data processing and general observer (astronomer) support.

The observatory operations tasks include monitoring the health and status of the observatory and developing and distributing by satellite the observation sequences during Chandra's communication coverage periods.

The science data processing tasks include the competitive selection, planning, and coordination of science observations with the general observers and the processing and delivery of the resulting scientific data. Each year, there are on the order of 200 to 250 observing proposals selected out of about 800 submitted, with a total amount of observing time about 20 million seconds.

X-ray astronomy can only be performed from space because Earth's atmosphere blocks X-rays from reaching the surface. The Chandra Observatory travels one-third of the way to the Moon during its orbit around the Earth every 64 hours. At its highest point, Chandra's highly elliptical, or egg-shaped, orbit is 200 times higher than that of its visible-light- gathering sister, the Hubble Space Telescope.

NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra Program for the Office of Space Science in Washington. The development contractor for the spacecraft was TRW, Inc., Redondo Beach, Calif. The Smithsonian's Chandra X-ray Center controls science and flight operations from Cambridge.