Backup Pad 39-B Found To Have Similar Deterioration, But Repairs Not Slated To Be Performed There: Briefers

Damage to a flame trench at Launch Pad 39-A at Kennedy Space Center will be repaired before the next major mission, the launch of Space Shuttle Atlantis Oct. 8 on a rescue run to the Hubble Space Telescope, NASA briefers said in a news teleconference after a two-hour meeting on how to repair the damage.

Repairs already have begun, after the blistering blast of 7 million pounds of thrust in the exhaust from Space Shuttle Discovery on May 31 ripped more than 5,000 flame- resistant bricks from a wall in the east flame trench.

The trenches guide shuttle exhaust away from the pad during launches.

Workers will rush the fixes forward, working two 10-hour shifts a day.

Flame trench damage occurred for several reasons, such as weakness at a fracture joint, corrosion on anchor plates, and a failure of structural epoxy, according to Perry Becker, engineering investigation team lead.

Other problems include carbonation, in which key materials leach out of concrete, leaving it weakened.

Those failings set up the crisis, when intense vibration and the searing hot plume of the Discovery exhaust got behind the bricks on the flame trench wall, causing some bricks to rip loose. And then, because the bricks are interlocked, there was a cascading failure of bricks, Becker said.

Also, an existing patch to fix earlier problems came loose, which created a path for the exhaust plume to get behind the bricks.

When they came loose in the shuttle exhaust that can reach 3,600 degrees Fahrenheit, bricks were sprayed out of the trench like automatic-weapon rounds at speeds greater than 1,000 feet per second, littering the ground up to 1,800 feet beyond the trench.

Briefers noted that the pad itself, which supports the shuttle system and crawler, wasn’t damaged.

Flame-trench decay also was found at nearby Launch Pad 39B during a "nondestructive" inspection, similar to the decay at Pad 39-A that preceded the massive damage May 31.

That damage at Pad 39-B is important because that pad might possibly be used this year. Space Shuttle Atlantis will launch Oct. 8 off Pad 39-A for the Hubble repair mission. Because Atlantis is going to the telescope, it won’t be able to use the International Space Station as a life raft in event of problems with the orbiter vehicle. Therefore, Space Shuttle Discovery will have to be sitting poised on Pad 39-B, ready to rush to the rescue of the crew on Atlantis, if it has problems.

However, NASA officials aren’t as concerned about decay found in the flame-trench area of little-used Pad 39-B. "We don’t plan to do anything to the walls" of that launch pad, a briefer said. She added that decay seen there won’t affect plans for Discovery to be poised and ready for that potential rescue mission.

Costs of the repairs to Pad 39-A likely will be less than $3 million.

It is possible that even after the just-begun repairs are completed, that in some future launch there could be further flame-trench damage with bricks ripped loose and sprayed out of the trench. But this isn’t a safety of flight issue, and it likely wouldn’t be so extensive that crews couldn’t perform further repairs before the next mission, according to briefers.

More extensive launch-pad renovation work will be performed before the next-generation U.S. spaceship, Orion-Ares, begins flying in the middle of the next decade.

No Danger To Shuttles

There was no danger to Space Shuttle Discovery in its launch on the STS-124 Mission to the International Space Station last month, briefers said.

Bricks didn’t ricochet back toward the trench or the shuttle, they explained.

Behind the wall surfaced with the bricks is a concrete wall supporting the launch pad above, and supporting the weight of the space shuttle orbiter vehicle, its external fuel tank and solid rocket boosters, plus the crawler transporter on which they ride from the Vehicle Assembly Building to the pad.

Briefers said they examined that inner wall and found no damage, so there never was a danger of that wall collapsing beneath the weight of the shuttle system and crawler.

In making repairs to the outer wall, concrete will be pumped under pressure to form a new wall.