NASA: Shuttle Temperature Rose Suddenly

NASA (news - web sites) officials said Sunday that space shuttle Columbia experienced a sudden and extreme rise in temperature on the fuselage moments before the craft broke apart.

NASA space shuttle program manager Ron Dittemore said the temperature rise — 60 degrees over five minutes in the mid-fuselage — was followed by an increased sign of drag that caused the shuttle's computerized flight control system to try to make an adjustment to the flight pattern.

Dittemore cautioned that the evidence was still preliminary, but that one of the possibilities was that there been damage or a loss of thermal tiles that protect the shuttle from burning up during re-entry into the Earth's atmosphere.

"We are making progress," Dittemore said, adding that the combination of new engineering data and an observer who reported seeing debris from the shuttle while it was still passing over California may create "a path that may lead us to the cause."

The shuttle broke up shortly before landing Saturday, killing all seven astronauts. Most of its debris landed in eastern Texas and Louisiana.

Earlier Sunday, NASA administrator Sean O'Keefe named a former Navy admiral to oversee an independent review of the accident, and said investigators initially would focus on whether a broken-off piece of insulation from the big external fuel tank caused damage to the shuttle during liftoff Jan. 16 that ultimately doomed the flight 16 days later.

"It's one of the areas we're looking at first, early, to make sure that the investigative team is concentrating on that theory," O'Keefe said.

Dittemore said the engineering data showed a temperature rise in the left wheel well of the shuttle about seven minutes before communication was lost with the spacecraft. One minute later, there was an even more significant temperature rise in the middle to left side of the fuselage.

The drag on the left wing began a short while later, causing the shuttle's automated flight system to start to make adjustments.

"There may be some significance to the wheel well. We've got some more detective work," Dittemore said.

The manufacturer of the fuel tank disclosed Sunday that NASA used an older version of the tank, which the space agency began phasing out in 2000. NASA's preflight press information stated the shuttle was using one of the newer super-lightweight fuel tanks.

Harry Wadsworth, a spokesman for Lockheed, the tank maker, said most shuttle launches use the "super-lightweight" tank and the older version is no longer made. Wadsworth said he did not know if there was a difference in how insulation was installed on the two types of tanks.

Wadsworth said the tank used aboard the Columbia mission was manufactured in November 2000 and delivered to NASA the next month. Only one more of the older tanks is left, he said.

O'Keefe emphasized that the space agency was being careful not to lock onto any one theory too soon. He vowed to "leave absolutely no stone unturned."

For a second day, searchers scoured forests and rural areas over 500 square miles of East Texas and western Louisiana for bits of metal, ceramic tile, computer chips and insulation from the shattered spacecraft.

State and federal officials, treating the investigation like a multi-county crime scene, were protecting the debris until it can be catalogued, carefully collected and then trucked to Barksdale Air Force Base in Louisiana.

The effort to reconstruct what is left of Columbia into a rough outline of the shuttle will be tedious and painstaking.

When a shuttle piece was located this weekend, searchers left it in place until a precise global position satellite reading could be taken. Each shuttle part is numbered; NASA officials say experts hope to trace the falling path of each recovered piece.

The goal is to establish a sequence of how parts were ripped off Columbia as it endured the intense heat and pressure of the high-speed re-entry into the atmosphere.

At least 20 engineers from United Space Alliance, a key NASA contractor for the shuttle program, were dispatched to Barksdale for what is expected to be a round-the-clock investigation.

Other experts, including metallurgists and forensic medicine specialists, are expected to join the investigation. Their focus will be on a microscopic examination of debris and remains that could elicit clues such as how hot the metal became, how it twisted and which parts flew off first.

In addition to NASA's investigation, O'Keefe named an independent panel to be headed by retired Navy admiral Harold W. Gehman Jr., who previously helped investigate the 2000 terrorist attack on the USS Cole (news - web sites).

Gehman's panel will also examine the Columbia wreckage, and come to its own conclusions about what happened. O'Keefe described Gehman as "well-versed in understanding exactly how to look about the forensics in these cases and coming up with the causal effects of what could occur."

Joining Gehman on the commission are four other military officers and two federal aviation safety officials.

Officials used horses and four-wheel-drive vehicles to find and recover the shuttle pieces. Divers were being called in to search the floor of Toledo Bend Reservoir, on the Texas-Louisiana line, for a car-sized piece seen slamming into the water.

Some body parts from the seven-member astronaut crew have been recovered and are being sent to a military morgue in Dover Air Force Base in Delaware.

Columbia came apart 200,000 feet over Texas while it was streaking at more than 12,000 miles an hour toward the Kennedy Space Center (news - web sites). A long vapor trail across the sky marked the rain of debris.

1440 GMT (9:40 a.m. EST)
During a mission status news conference yesterday, Entry Flight Director Leroy Cain was asked about any possible damage to the shuttle's thermal tiles during launch. The tiles are what protect the shuttle during the fiery reentry into Earth's atmosphere.
Tracking video of launch shows what appears to be a piece of foam insulation from the shuttle's external tank falling away during ascent and hitting the shuttle's left wing near its leading edge.
But Cain said engineers "took a very thorough look at the situation with the tile on the left wing and we have no concerns whatsoever. We haven't changed anything with respect to our trajectory design. It will be a nominal, standard trajectory."

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I have always wondered why NASA didn't put shields, or pants, on the leading edges of the Shuttle. These shields would be on the nose and leading edges of the wings and tail, and would stay in place during ascent and orbit, then jettisoned just prior to re-entry.

NASA put a full cover shield over the Apollo command module vehicles call a Boost Protection Cover (BPC) that was jettisoned just prior to reaching orbit.

"The tile damage was done after liftoff. After Main Engine Cut Off there was literally nothing NASA could do. "

Here you go:

RTLS: Return to Launch Site

An engine fails within the first few minutes of flight, or a systems problem (cabin leak, loss of cooling, etc.) occurs which requires the shuttle to come home early. In this case, the shuttle will fly downrange a bit, and then do a flip: it's originally travelling east, with the ET on "top" (away from the earth). During this flip maneuver, the shuttle will rotate so that its nose and tail swap places, and at the end the shuttle is flying backwards into is own exhaust, with the tank on the bottom. Eventually this will negate all of its forward momentum, and start to move back towards KSC. Then it's just a matter of dropping the ET and gliding back to the Cape. The whole thing takes about 25 minutes.

TAL: Transoceanic Abort Landing

If a problem occurs after the last RTLS capability, then the shuttle will have to land on the other side of the Atlantic. Depending on inclination, this will be either in Africa (Ben Guerir, Morocco) or Spain (Zaragoza or Moron). A TAL takes about 35 minutes.

"How much do the suits weigh? Assume they weigh 500# each. Is the paylosd calculated so closely that the additional 1000# would be too far outside the max takeoff weight?"

It is not just the suits, it is special airlock equipment that goes on the Orbiter when they carry suits, additional consumables (because they have to partially depressurize and repressurize the vehicle, and other stuff. I am talking off the top of my head, but I think a planned spacewalk requires about 2-3K of payload. With Columbia I think the max payload at 150 NMI was about 45K -- but that is for a 28.5 deg inclination orbit. AFAIR it was something like 30K to the ISS at the ISS inclination (which is over 50 deg, but I do not remember exactly. So 3K is a big hit.

"That's a real revelation. I always thought that they were like refractory brick. That is why I had such a hard time seeing how a piece of insulation could damage the tiles. So, if it is like styrofoam, the individual shaping would not be a problem as a custom cut from an oversize square blank should be fairly simple."

The consistency of styrofoam. They are not made up of a uniform material that you can cut with a matte knife. Each tile is individually cast, and they do magic things in the manufacturing process to combine spun glass and vacuum in such a way as to provide maximum insulation. (Magic in the sense that the ceramics engineers do stuff that this orbital mechanic does not understand.) So, you cannot bring up a sheet of thermal tile, an exacto knife and some ducco cement, cut to shape and hammer to fit.

Additionally there is the problem of getting an astronaut in a EVA suit to fit the tile into place. The astronaut is orbiting the Earth (at a slightly different orbit than the Orbiter, so they tend to drift apart), and need to station keep -- to an inch or two -- over a spot on the vehicle. Now that person had to take a tile that can be easily cracked in a gloved hand and handle it with the same delicasy as that worker on earth manages with a thin cotton glove.

To give a crude analogy (in both senses) imagine a man trying to arouse his wife while wearing welder's gloves. And not scratch her in the process. Most EVA activities are pretty unsubtle. Bang, boom, slam home a latch. Twist a rod using your entire upper body.

"Why would it be necessary to send a whole space shuttle up for repair or rescue? We send up heavy 3 stage rockets all the time to put satellites into orbit. It could carry provisions, repair materials, or even a small lifting body. It would seem to me that having something like that on standby would be money well spent."

Because the Orbiter is the only vehicle in NASA's inventory that could hold 10 people. You really need a crew of three to fly the thing. (Yeah, two in a pinch, but they have not trained that way since at least 1986.) Then you have to bring down seven. We have NO man-rated system that can be attached to a disposable, and even if we did, liquid-fueled disposables take a month or so to prep (assuming you did not keep one hot, with a rescue system aboard during each manned mission). And we simply do not launch massive payloads, requiring a booster large enough to send a 7-10 man rescue capsule into a rendevous with a crippled Orbiter ofen enough to expect to have one ready to launch (except for switching out the payload capsule) 24-7. So you have the same problem as with an Orbiter. By the time you set it up, the crew is dead.

Could we have a smaller "rescue system" with supplies, intended to keep the crew alive until a rescue mission could be launched? In theory, yes, but it would be pricey. And a lifting body crew rescue system is a great idea. So great that NASA has attempted to design such a thing on about three occasions, only to have Congress defund the effort at or just after the stage where they start cutting steel.

All of this comes down to the classic engineer's trade-off cost vs. benefit. We can diddle around with dramatic rescue systems that can rescue people in even the most extreme situations or we can make sure that those situations don't happen in the first place.

One real cheap fix is to stop adding spray-on foam insulation to the ET -- at least in winter. Or work harder to protect the tiles from strikes during launch. A little further up the expense tree is finding a substitute for the Thermal Protection System. But once you get into dedicated rescue vehicles, you are adding a spare tire that costs as much as the car.

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