Sen. William Proxmire, D-Wis., has warned NASA that cost-consciousness will probably determine its job into the next century, even though the space agency is reinvigorated by the shuttle Discovery's mission.

But NASA officials say they are ready to reclaim America's leadership in space with the successful four-day journey into the cosmos by Discovery's five-man crew.Earth-bound decision makers debated the aims of the American space program Sunday amid the first U.S. manned mission since the shuttle Challenger blew up Jan. 28, 1986.

Proxmire, a ranking Democrat on the Senate Budget Committee, said the primary concern for the National Aeronautics and Space Administration now is money. The next president will have to decide whether to spend it on ambitious, expensive proj-ects, such as the planned space station and a manned mission to Mars, he said.

"Come next May, the president will have to make a decision - after the election is over - to decide whether he wants to do something about the deficit or decide whether he wants to go ahead with the shuttle, which in my view will cost $30 billion," Proxmire said on NBC's "Meet the Press."

Noting the presidential candidates, Repubican George Bush and Democrat Michael Dukakis, have expressed support for the space station, Proxmire predicted, "I think they'll both have second thoughts, whichever is president come next May and has to deal with the deficit."

But NASA Administrator James Fletcher, on CBS's "Face the Nation," said the United States must take advantage of the space agency's demonstration that it can regroup after disaster.

"The whole world watches when we are successful and the whole world watches when we have a failure," said Fletcher, who took charge of NASA just after the Challenger explosion and oversaw the rebuilding program. "How can we lead the rest of the world if we give up something like manned space?

"It's a small part of the federal budget, about 1 percent or perhaps less. As long as it stays in there, no one is going to notice the expenditures on space, but they certainly would notice it if we gave up on the manned space program."

Rep. Bill Nelson, R-Fla., who flew on the shuttle mission shortly before Challenger, argued on the NBC program the shuttle has been worth the cost.

"If it were a white elephant, why does everyone else on planet Earth want one? Why do the Soviets have one that looks almost like ours? Why do the French say that they want it?" Nelson said.

Before the Challenger accident, "we thought that (the shuttle program) was going to be the space transportation system. It was going to carry everything into space, and that was a mistake, in retrospect. We should complement the space shuttle, which will fly humans to space, with the expendable rockets that will put up the unmanned payload," he said.