SPACE CENTER, Houston--The disaster of space shuttle Challenger, in contrast to the stunning success of Voyager's fly-by of the planet Uranus, will sharpen the argument that the U.S. should abandon manned missions and instead send robots to explore the universe, scientists said yesterday.

Unmanned space travel costs far less than manned missions and can probe much deeper in space with no risk to humans. Yet it remains the poor stepchild to the high-flying manned space program, experts said.

It's a debate that has raged in the scientific community since the first days of exploring the heavens.

"Nobody wants to say `I told you so' the day after seven people have died," said Gordon Pettengill, a planetary astronomy professor at the Massachusetts Institute of Technology. "I wouldn't be surprised if this did cause some reexamination. It would be strange to me if it didn't."

While experts are hesitant to revive the debate so soon after Tuesday's tragedy in which the seven crew members were killed, concerns are surfacing over the impact the Challenger accident will have on unmanned projects.

"I don't want to sound callous but one of the things we always worry about in a tragedy like yesterday's is the money it's going to take to correct [the problem] is likely to come out of the hide of unmanned [projects]," said John W. Freeman, a Rice University space physicist.

"The thing that strikes me is that this happened four days after the successful Voyager rendezvous with Uranus, a planet we've never even had a photograph of," said Dr. Edward Ney, a University of Minnesota professor of physics and astronomy and a shuttle critic.

Data recently radioed back by Voyager 2 have given scientists new photographs of the five major moons of Uranus. The moon Miranda emerged as an icy world unlike any other ever seen in the solar system.

In a recent issue of Scientific American, Dr. James Van Allen, a longtime shuttle critic, argued that manned flights were diverting important resources from unmanned probes.

"It's been an uphill battle. The public doesn't always appreciate what has been learned from unmanned missions," Freeman said. "As it stands right now, manned space flight is budgeted much greater than unmanned."

Many scientists argue that a greater balance should be struck between the use of humans and robots in space.

Machines cannot perform all functions an astronaut can, shuttle proponents note. And the future space station program may yield untold benefits, they argue.

"NASA has always given great weight to both the manned and the unmanned part of the space program," said William Graham, acting administrator of the space agency. "We'll continue our program of people and machines working together."

At the Jet Propulsion Laboratory (JPL) in Pasadena, Calif., which runs America's unmanned space program under contract to NASA, a Voyager 2 expert said the space shuttle program is needed to launch unmanned probes.

"I would feel very badly now if we would try to abandon the shuttle," said Ellis Miner, JPL's deputy project scientist for Voyager 2. "We have no way of launching anything to the planets except for the space shuttle."