NASA plans to eliminate 5,000 space shuttle jobs over five years so that it can afford such ambitious projects as the building of a lunar base and a flight to Mars.

"All of those things cost money, and there aren't going to be many new bucks for NASA to work with," Robert Crippen, the new Kennedy Space Center director, said in a televised address Monday to Kennedy workers."Consequently, we need to be able to reduce programs like the shuttle but do it safely so that we can do these other exciting things."

Crippen, a former astronaut, said budget cuts will result in the loss of about 20 percent of the 25,000 shuttle jobs nationwide. Much of that will be achieved through attrition, but there will also be layoffs, he said.

Last fall, 400 shuttle workers at Kennedy were laid off.

Other savings will be achieved by cutting some of the checks and balances added to the shuttle system following the Challenger explosion that killed seven astronauts in 1986. Crippen said that wouldn't jeopardize safety.

"Safety is our No. 1 concern and will remain so," Crippen told workers.

Some shuttle workers will be transferred to other projects and Crippen expects the number of Kennedy workers - about 20,000 - will remain stable over the next several years.

Of NASA's $14.3 billion budget for the fiscal year that began Oct. 1, nearly $2.7 billion is for shuttle operations. Last year's shuttle operating budget was $2.8 billion.

Shuttle managers have been ordered to reduce spending 3 percent a year over the next five years.