Satellite Lost on Challenger to Be Replaced

A replacement was ordered by NASA on Thursday for the giant, part-secret $250-million satellite lost in the space shuttle Challenger explosion.

The National Aeronautics and Space Administration announced plans to buy a Tracking and Data Relay Satellite and parts for a backup spacecraft from TRW in Redondo Beach, Calif. The value of the contract will be negotiated with the firm, NASA said, with delivery scheduled in September, 1991.

The satellite--the largest and most advanced communications satellite in the world--was in the Challenger cargo bay when it exploded on liftoff Jan. 28. An underwater search for its debris is still under way.

Acts as Switchboard

NASA has had poor luck with the satellite, which functions as a switchboard in orbit, able to track the space shuttle and relay television and telemetry signals.

It weighs 5,000 pounds and measures 57 feet across its solar panels. The electronic relay system can handle up to 300 million bits of information each second simultaneously from up to 25 orbiting spacecraft.

The space agency had planned to have three of the satellites on station, 22,300 miles above the Earth, three years ago.

The first one was ejected from the shuttle’s cargo bay by springs on April 5, 1983, and was propelled higher by an attached rocket.

But something went wrong during the second of two rocket firings, and the satellite began tumbling in a useless orbit, 8,600 miles from its goal.

Thimble-Size Jets

Using a few thruster jets no bigger than thimbles, engineers slowly nudged the satellite into place over a two-month period. Since then, it has provided coverage of half the Earth.

The second satellite had been scheduled for launching in August, 1983, but was postponed because of the first failure. The satellite was put aboard the Challenger for a March 7, 1985, flight, but the launching was canceled when the satellite in orbit experienced problems in its timing circuits.

The second satellite next was loaded on the ill-fated Challenger flight.

In a related development, Administration officials said Thursday that objections raised by White House Chief of Staff Donald T. Regan have delayed a multibillion-dollar decision by President Reagan on a replacement for Challenger.

Although a final decision and announcement had been expected by the end of the week, the officials said Regan has demanded--and not yet received--further justification from NASA to support construction of a new shuttle.