Spaceflight Now: Space Station/STS-98

NASA managers assess booster repair options

Posted: December 17, 2000
Updated: 9:30 a.m. EST, December 19
Updated: 4:30 p.m., 4:45 p.m. EST, December 19

The mission patch for STS-98 -- Atlantis' voyage to deliver the Destiny module to the international space station. Photo: NASA
The shuttle Atlantis' rollout to pad 39A for launch on a critical space station assembly mission will be delayed at least until Jan. 2 to complete booster wiring repairs and to give work crews holiday time off, NASA officials announced today.

The shuttle's launch, originally targeted for Jan. 18, is expected to slip a few days to Jan. 21 or 22 at the earliest.

But the Air Force Eastern Range, which provides radar and tracking support for all rockets launched from the East Coast, currently is booked Jan. 21 through Jan. 23 for pre-launch tests of an Air Force Titan 4 rocket at the nearby Cape Canaveral Air Force Station.

NASA managers plan to meet Wednesday to assess the shuttle repair plan, the processing schedule and range availability. A new launch target date could be set Wednesday afternoon.

At issue is what to do about crumbling shielding on cables in one area of the shuttle's booster separation system. A repair option has been developed that can be accomplished without "destacking" the shuttle and its external tank.

But additional analysis will be required to give NASA managers confidence similar problems don't lurk elsewhere in the separation system.

The goal of mission STS-98 is to deliver the U.S. laboratory module, Destiny, to the international space station. The 32,000-pound module is scheduled to be delivered to the launch pad payload changeout room Jan. 3 for installation in Atlantis's cargo bay.

Atlantis originally was scheduled to be hauled to launch pad 39A on Dec. 11, but the move was held up when engineers discovered a booster separation problem that occurred during launch of the shuttle Endeavour on Nov. 30.

During Endeavour's launching, one of two explosive cartridges used to separate a strut holding the base of the orbiter's left-side solid-fuel booster to the ship's external fuel tank failed to fire.

A redundant "NASA standard initiator," or detonator, inside the strut in question did fire, however, and the booster separated cleanly. As it turned out, a wiring problem prevented the detonation signal from reaching the initiator.

But analysis indicates a shuttle would fly out of control and begin breaking up within seconds if both detonators in a given booster attach strut failed to fire. As a result, NASA managers decided to make sure the booster separation system used by Atlantis was healthy before moving the shuttle to the launch pad. Atlantis's rollout then was delayed to give engineers time to X-ray wiring in the separation system and to review ground processing.

"On Friday, a cable located in the lower strut of (Atlantis's) left-hand booster failed a standard (electrical) resistance check," NASA spokesman Joel Wells said in a recorded status report Sunday. "On Saturday, managers decided to replace a faulty connector on that cable.

"Meanwhile, workers performing final X-rays on cables located in the SRB forward skirt identified a damaged outer shield on one ordnance cable. While replacing that cable connector, workers had to peel back an outer layer of shielding. During that process, technicians noticed a loss of integrity on an inner layer of cable shielding.

"Further inspection revealed a crumbling effect on most of that shielding layer throughout that single cable," Wells said. "Engineers are now evaluating the cause of this cable issue and work planners are discussing plans to replace this entire cable."

After additional analysis, engineers developed two repair options that did not require destacking.

Assuming no additional inspections will be required to check other cables in the booster separation system, Atlantis should be ready for launch within a few days of its original Jan. 18 target. But if analysis indicates additional inspections and/or repairs are required, the flight likely would slip into February.

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