In the eyes of NASA, it's a structure that is blocking the development of the space shuttle. In the eyes of historic preservation groups, it's an important part of a national historic site. And so a battle is heating up over the space agency's plans to demolish the last Apollo launch tower at the John F. Kennedy Space Center and allow it to be sold as scrap metal.

The 380-foot tower and the mobile launch pad on which it rides once pointed the way for Americans to moon travel. It was used to launch Apollo 11, the first manned spacecraft to land on the moon, all three Apollo-Skylab manned missions and the Apollo-Soyuz test project.

NASA said it must award a demolition contract by Friday or risk falling behind schedule on its Space Shuttle program. The tower must be removed by October because NASA needs to begin modifying the mobile launch pad then for use by the shuttle program, beginning in 1986.

Earlier this month, NASA agreed to delay the schedule a week to give the preservationists a chance to suggest alternate ways of removing the tower. But NASA officials said yesterday that none of the suggestions are practical.

Rep. Bill Nelson (D-Fla.), whose district includes the space center, asked House colleagues late yesterday to sign a letter urging NASA to postpone awarding the contract for 60 days. The letter also asked NASA to hire an independent firm to estimate the cost of dismantling the tower and reassembling it somewhere else at the space center.

The battle over the tower began after two Air Force engineers at the space center organized a grass-roots campaign to save it. Joseph Fury and John London Jr. say the tower could be a major tourist attraction.

"I'm sure tourists would love to ride up the same elevator that the astronauts rode on their way to the moon," Fury said. He added that the tower also would give visitors an excellent view of the space center and Cape Canaveral Air Force Station, which is next door. A Saturn rocket, like one used on Apollo flights, could be mounted next to the tower to demonstrate what the flights looked like, he said.

In a letter to Nelson, NASA said it would cost up to $4 million to remove the tower and reassemble it for display. It also would be impractical to add a Saturn 5 rocket because "extensive structural modifications" would be necessary because of "corrosion problems" and to enable the display "to withstand hurricane wind conditions," NASA said.

NASA has accepted a low bid of $557,000 to remove the tower. The demolition company would keep the steel, believed to be worth $400,000 as scrap. The coalition of historic groups contends that the tower could be removed and reassembled for about $1 million, but concedes that figure is an estimate.

The coalition maintains that NASA's plans have violated a 1974 agreement between the agency and the Florida Historic Preservation Society. The agreement was signed when the National Park Service added Launch Complex 39, including the tower and mobile launch pad, to its National Register of Historic Places.

At the time, NASA warned Florida officials that it planned to "completely disassemble and remove" the three towers at the site. (Two have been demolished.) But Robert R. Garvey Jr., executive director of the federal Advisory Council on Historic Preservation, said, "In the terminology of preservationists, there is considerable difference between the words 'disassemble' and 'demolish.' "

Garvey has sent NASA a telegram noting that the agreement called for "disassembly," but so far, he has not received a reply. While the council was created to arbitrate disputes over historical properties involving federal agencies, it does not have enforcement authority.

Edward P. Andrews, director of flight and turnaround operations at NASA, said yesterday that NASA has complied with the agreement.

NASA has offered the coalition free storage and a site for the tower if it wants to pay the contractor to dismantle and move it, he said.