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| CAPE CANAVERAL, Fla., Feb. 1 — Investigators trying to figure out what destroyed space shuttle Columbia focused immediately on the left wing Saturday and the possibility that its thermal tiles were damaged far more seriously than NASA realized by a piece of debris during liftoff. | |||||
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JUST A LITTLE over a minute
into Columbia’s launch Jan. 16, a chunk of insulating foam peeled away
from the external fuel tank and smacked into the left wing. Saturday, that same wing started exhibiting sensor failures and other problems 23 minutes before Columbia was scheduled to touch down. With just 16 minutes remaining before landing, the shuttle disintegrated over Texas. Just a day earlier, on Friday, NASA’s lead flight director, Leroy Cain, had declared the launch-day incident to be no reason for concern. An extensive engineering analysis had concluded that any damage to Columbia’s thermal tiles would be minor. “As we look at that now in hindsight ... we can’t discount that there might be a connection,” shuttle manager Ron Dittemore said hours after the tragedy Saturday. “But we have to caution you and ourselves that we can’t rush to judgment on it because there are a lot of things in this business that look like the smoking gun but turn out not even to be close.” The shuttle has more than 20,000 thermal tiles to protect it from the extreme heat of re-entry into the atmosphere. The black, white or gray tiles are made of a carbon composite or silica-glass fibers and are attached to the shuttle with silicone adhesive. |
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Loose, damaged or missing tiles can change the aerodynamics of a spaceship and warp or melt the underlying aluminum airframe, causing nearby tiles to peel off in a chain reaction. If the tiles start stripping off in large numbers or in crucial spots, a spacecraft can overheat, break up and plunge to Earth in a shower of hot metal, much like Russia’s Mir space station did in 2001. Dittemore said the disaster could have been caused instead by a structural failure of some sort. He did not elaborate. |
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NO OTHER PROBLEMS NOTED As for other possibilities, however, NASA said that until the problems with the wing were noticed, everything else appeared to be performing fine. NASA officials said, for example, that the shuttle was in the proper position when it re-entered the atmosphere on autopilot. Re-entry at too steep an angle can cause a spaceship to burn up. Senior U.S. officials told NBC News that there was no indication of terrorism. At an altitude of 39 miles, the shuttle was out of range of any surface-to-air missile, a senior government official said. If the liftoff damage was to blame, the shuttle and its crew of seven may well have been doomed from the very start of the mission. Dittemore said there was nothing the astronauts could have done in orbit to fix damaged thermal tiles and nothing flight controllers could have done to safely bring home a severely scarred shuttle, given the extreme temperatures of re-entry. The shuttle broke apart while being exposed to the peak temperature of 3,000 degrees on the leading edge of the wings, while traveling at 12,500 mph, or 18 times the speed of sound. Anthony Beasley, an astronomer at the California Institute of Technology, reported seeing a trail of fiery debris behind the shuttle over California, with one piece clearly backing away and giving off its own light before slowly fading and falling. Dittemore was unaware of the sighting and did not want to speculate on it. If thermal tiles were being ripped off the wing, that would have created drag, and the shuttle would have started tilting from the ideal angle of attack. That could have caused the ship to overheat and disintegrate. |
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The tiles were
damaged during Columbia's liftoff Jan. 16 at Kennedy Space Center in
Florida. |
 NO CHANCE OF REPAIRS Dittemore said that even if the astronauts had gone out on an emergency spacewalk, there was no way a spacewalker could have safely checked under the wings, which bear the brunt of heat re-entry and have reinforced protection. Even if they did find damage, there was nothing the crew could have done to fix it, he said. “There’s nothing that we can do about tile damage once we get to orbit,” Dittemore said. “We can’t minimize the heating to the point that it would somehow not require a tile. So once you get to orbit, you’re there and you have your tile insulation, and that’s all you have for protection on the way home from the extreme thermal heating during re-entry.” |
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Hunt
for shuttle answers begins
| Structural, Systems Integrity Focus Of Shuttle Probe | |
| By William Scott | |
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Investigators probing the loss of space shuttle Columbia on Feb. 1 at about 9 a.m. EST during re-entry will probably focus on structural- and systems-integrity.
Data sent via telemetry from the orbiter are being scrutinized for clues that could explain the vehicle's high-altitude break-up.
"We'll be poring over that data 24 hours a day for the foreseeable future," said Ron Dittemore, NASA's space shuttle program manager.
Although details are still slowly emerging from NASA, it appears that both voice and telemetry signals were lost shortly after Columbia emerged from the "blackout" portion of the reentry. Milt Heflin, NASA's Chief Flight Director, said "all vehicle data" were lost when Columbia was at 207,135 ft. altitude and Mach 18.3.
At a mid-afternoon press briefing, Heflin outlined a sequence of sensor readings and the loss of those readings: - 8:53 a.m. EST - Lost left wing inboard and outboard hydraulic temperature sensors. - 8:56 a.m. EST - Left main tire and brake line temperatures increasing. - 8:58 a.m. EST - "Bondline" temperatures from sensors in the vehicle structure were lost. Three of these were on the left wing's inboard and outboard elevons. - 8:59 a.m. EST - Left main gear tire temperatures and pressures were lost; these involved eight separate sensor measurements. At about this time, a tire pressure alert was displayed to the shuttle crew, and was apparently acknowledged verbally. This was believed to be the crew's last transmission.
U.S. officials identified several primary areas for investigators' initial focus: - The trajectory flown by the shuttle as it entered the upper atmosphere. A too-steep approach could cause excessive heating of the vehicle's structure, which could lead to its failure. - Integrity of the orbiter's structure throughout the reentry. - The flight controls, including both the reaction control system (RCS) small thrusters that let astronauts fly the orbiter in space -- and aerodynamic surfaces, such as elevons on the aft edge of the wing, which control the vehicle within the atmosphere. - Possible damage to the thermal protection system (TPS), the white and black tiles that protect the vehicle from excessive heat. During Columbia's liftoff, a piece of insulation from the external fuel tank fell off and hit the orbiter, apparently on the leading edge of the left wing. Whether this impact significantly damaged protective tiles or not, and had any effect on the shuttle orbiter's ultimate breakup during re-entry, is being studied.
"We spent a goodly amount of time reviewing" film of the insulation falling off, "and then analyzing" it to see "would there be any consequences," Dittemore told reporters. "It was judged that that event did not represent a safety concern. As we look at that now in hindsight, and certainly we have, all the indications were on the left wing. We can't discount that there might be a connection, but we can't rush to judgment on it."
Information from several Defense Dept. space-monitoring facilities will also be key to the investigation. Infrared sensors on U.S. Defense Support Program (DSP) satellites are believed to have captured data that could help NASA determine what was happening to Columbia during reentry. Officials at the North American Aerospace Defense Command (NORAD) said they are supporting NASA, but declined to comment on specifics.
NORAD provides missile warning and space-object tracking primarily for defense purposes, but its Space Control Center in Cheyenne Mountain, Colo., also monitors shuttle launches and on-orbit operations. Using a number of space surveillance systems, NORAD, Air Force Space Command and U.S. Strategic Command provide debris-avoidance information to NASA when the shuttle is in space. |
