Shuttle Launch Pad Damaged
Published on Jun 2, 2008 at 5:08 pm.
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Filed under NASA, space shuttle.
A couple of days ago, the Space Shuttle Discovery lifted off from Launch Pad 39A at the Kennedy Space Center to begin the STS-124 mission to the International Space Station. Space Launch Complex 39 (Kennedy Space Center) has two launch pads: 39A and 39B. These two launch pads were originally constructed in the 1960s for the giant Saturn V rockets used by the Apollo missions to the Moon. They used to support Skylab in the 1970s. Then, they were modified to accommodate the Space Shuttle program. These two launch pads, plus one built (but never used for that purpose) at Vandenberg Air Force Base are the only places that were equipped to handle shuttle launches.
Many earlier launch pads were just that: concrete pads from which that rockets launched. But, the Saturn V rockets had enormous engines that took a few seconds to achieve sufficient thrust for the rocket to lift off. During those seconds, massive amounts of kerosene were being burned. The heat from those flames would have destroyed the bottom of the rocket and the launch pad structure unless something were done to deflect the blast away from the rocket itself. So, directly underneath the rocket exhaust was a wedge shaped structure directing the hot exhaust gases to the side, along two concrete and brick trenches that carried the exhaust away from the rocket and pad structure. These are the flame trenches.
The Space Shuttle also needs the flame trenches to deflect the exhaust away from the spacecraft itself. The pressure, heat, and physical forces from all of that hot gas flowing through the flame trenches are enormous. They really take a beating. And, Pad 39A has taken a longer beating than 39B. The first launch from Pad 39A was in 1967. Pad 39A was taken out of service in 1973 to make the necessary modifications to support Space Shuttle missions. It returned to service in 1981 with the first Space Shuttle Launch: STS-1. After the Apollo Soyuz Test Project, launch pad 39B was taken out of service to prepare it for Space Shuttle operations, too. However, it did not see action again until 1986 when the Challenger lifted off from LC-39B on its final disastrous mission, STS 51-L. Last year, launch pad 39B was deactivated as an active launch site to prepare for conversion to support the Constellation program and the Ares Rocket that are to follow the Space Shuttle. The Space Shuttle infrastructure, though, is still there so that pad 39B can act as a backup in the event that a rescue mission is needed for the STS-125 mission to the Hubble Space Telescope now scheduled for October of this year.
But, during the launch of STS-124 two days ago, the flame trench for Pad 39A was seriously damaged. The flame trench is 42 feet deep, 58 feet wide, and 450 feet long. You can see from the picture at the top that some of the concrete facing has buckled and been dislodged. But, the pictures below show that the wall of the trench itself is damaged, and debris was thrown all the way to a perimeter fence.
Now, as you can imagine, with the awesome forces at work on these trenches, this is not the first time that they’ve been damaged during a lift off. The debris was thrown outward by the hot exhaust gas, so it almost certainly posed no danger to the Space Shuttle itself. Of course, you wouldn’t have wanted to be anywhere in the direction that the debris was being thrown! (With the hot gas going out that direction, you would not have wanted to be in the area even without debris!)
Reportedly, the damage, though extensive, is nowhere near severe enough to delay the STS-125 mission in October. The damage is described as serious, but that could simply mean that it will take weeks or months to get it fixed. Clearly, you would not want to launch another shuttle from this site without fixing the damage. That is what is meant by serious. It is not unprecedented. Of course, it could be somewhat indicative of the aging infrastructure at KSC. At any rate, NASA does not seem too concerned about it.
-Astroprof
Images from Spaceflight Now, originally for a story for CBS News “Space Place”
