The space agency has unveiled a national competition that invites schoolchildren to come up with a name for the new shuttle that will replace Challenger in the early 1990s, officials said.

"The name chosen should not only identify an American spacecraft but also should capture the spirit of America's mission in space," NASA said in a statement. "In honor of the seven crew members lost in the Challenger accident, the name Challenger has been retired."Challenger was destroyed Jan. 28, 1986, by a booster failure. All seven crew members, including New Hampshire school teacher Christa McAuliffe, were killed in history's worst space disaster.

Along with eliminating any form of the name "Challenger" from the competition, NASA restricted the competition to continue the agency's tradition of naming shuttles after exploratory or research sea vessels. NASA's three operational shuttles Discovery, Atlantis and Columbia all were named after sea vessels, as was Challenger.

Entry forms and rules will be available in May and the winning name will be announced in May 1989.

Challenger's replacement, currently known only by its serial number, OV-105, is under construction at Rockwell International's shuttle assembly line at Palmdale, Calif. Scheduled for completion in April 1991, first flight is expected in 1992.

The "Orbiter-Naming Competition," conducted by NASA with the cooperation of the Council of Chief State School Officers, is open to elementary and secondary students in the United States and U.S. territories along with those attending overseas schools run by federal agencies.

To enter, students will have to form teams and research a name, NASA officials said. The name ultimately selected by a team will have to be justified in a classroom project, which must be completed during the 1988 fall semester. Entries must be postmarked by Dec. 31, 1988.

There are two entry divisions: kindergarten through sixth grade and seventh through twelfth grade. Each state, territory or agency will select one winner in each division one year from this month. The final winner in each division and the name selected by NASA for the new shuttle will be announced in May 1989.

Many schoolchildren across the nation related to Challenger's ill-fated voyage because of McAuliffe's presence on the spaceship.

Less than two months after Challenger's destruction, Rep. Tom Lewis, R-Fla., introduced a resolution calling for the name of a replacement orbiter to be selected by students.

NASA Administrator James Fletcher announced the program June 8, 1987, and the following October, Congress authorized the space agency to proceed with the plan.