Ground Shuttle Until Seals Are Fixed, Space Chief Says

The suspect joint between segments of the space shuttle’s solid rocket boosters should be modified or even redesigned before shuttles grounded by the Challenger tragedy are launched again, the acting administrator of the National Aeronautics and Space Administration said Tuesday.

“I don’t want to preempt the presidential commission on the accident,” space agency chief William R. Graham told the House Science and Technology Committee, “but, as an engineer reviewing a wide range of issues since the accident, it’s my view today that it would be very appropriate to modify the field joints on the (solid rocket boosters) before we return to space flight.”

Since the early days of the investigation of the Jan. 28 tragedy, in which the shuttle’s seven crew members were killed, experts have suspected that a failure of synthetic rubber O-rings sealing the joint between the lower segments of Challenger’s right solid rocket booster precipitated the accident. However, another theory has attributed the failure to the effect on the O-rings of abnormally cold weather on launching day, rather than a design flaw.

Graham’s recommendation that the joint be modified or redesigned suggested that the remaining three shuttles may be grounded much longer than the year now being estimated by NASA. A redesign, space agency sources said, would require not only equipment changes but a series of flights to test the modified rocket before it is used to launch the shuttle.

Graham said that NASA officials have already undertaken a complete review of launching schedules, with one schedule based on a fleet of three orbiters and another assuming four orbiters. The plan is to resume flights at a low rate that is “safe and appropriate to the system,” he said.

His recommendation to modify the solid rocket booster follows scathing criticism from chief astronaut John W. Young, who charged that launching schedules had compromised safety in the shuttle program. It coincided with mounting pressure on the Reagan Administration and Congress to decide whether to seek funds for a new orbiter to replace the Challenger.

Graham put the cost of the accident at about $3.2 billion, not including the tracking and data relay satellite carried in the spacecraft’s cargo bay when it exploded nine miles above the Florida coast. A new orbiter to replace the Challenger could be built for $2.8 billion and delivered to the space agency in about three years, he said.

Wants More Funds

NASA hopes to get White House approval of a supplemental budget request for fiscal 1986 to start work on a replacement shuttle, but the Administration’s position is still being debated by an interagency panel headed by national security adviser John M. Poindexter.

Graham told the House panel that a decision to proceed immediately with construction of a new orbiter might require a supplemental appropriation of $500 million in the space agency’s budget for the current year--$300 million to start work on a new orbiter and $200 million for other costs resulting from the accident. The accident investigation and salvage operations alone could cost as much as $50 million, he estimated.

NASA Comptroller Thomas Newman said that the catastrophe’s financial effects will be felt most severely in the fiscal 1987 space agency budget, in which an additional $900 million will be needed to prepare the system to fly again and to press work on a Challenger replacement.

Besides the question of replacing the Challenger, the Administration is considering constructing expendable rockets to be used for routine satellite launchings.

According to sources, the interagency panel, including officials of the Transportation and Defense departments, as well as NASA, has had difficulty agreeing on a plan to be presented to the President, while the Office of Management and Budget made consideration of the budget deficit a chief concern.

Graham told the House panel that NASA will have by 1990 a backlog of space payloads equivalent to 24 shuttle missions. Unless a fourth orbiter is brought into the fleet, he said, that backlog will continue to grow.