In the trail of shattered metal, scorched tiles and human remains that fell from the disintegrating space shuttle Columbia across Texas and Louisiana, accident investigators may be able to read the cause of the catastrophe, aerospace experts said yesterday.
"It's a daunting task, because the evidence is spread over 500 miles," said John C. Macidull, an engineer and former Navy test pilot who was a lead investigator of the Challenger disaster in 1986. "But it is possible."
One critical task is establishing the sequence of events leading to the breakup of the 90-ton craft 39 miles over Texas.
"You usually work backwards from the pieces that flew off first, to the cause of the initial failure," said Jim Burnett, who was chairman of the National Transportation Safety Board when the Challenger blew apart shortly after launch.
In an investigation that is likely to take months, everything from amateur videos of the smoking debris arcing toward earth to decades-old paperwork documenting the design of shuttle parts is likely to be scrutinized by scientists.
The investigators will use microscopic examination and chemical tests on metal scraps to determine where they originated on the shuttle and how they broke off. They will examine critical parts of the remaining three shuttles, trying to locate design weaknesses.
"You've got to look at everything," said Robert B. Hotz, who was editor of Aviation Week for 25 years and later served on the presidential commission that investigated the Challenger. "When you start out on an accident investigation you don't know where it's going to lead."
Just beginning
NASA officials were considering yesterday whether overheating on the left side of the 122-foot craft may have caused the breakup, possibly because insulating tiles had fallen off.
But both NASA officials and outside experts emphasized that the quest for answers in the tragedy is just beginning. It's important not to leap to any single conclusion, thus closing out other possibilities, they said.
"The first thing is to gather materials, recollections, data and imagery," said James E. Oberg, who worked at Mission Control for 22 years and is now an aerospace author and consultant. "It can be damaging to jump too quickly to any hypothesis."
Ron Dittemore, NASA's shuttle program manager, offered a similar caveat even as he told a press conference last night what he knew.
"First reports are notoriously unreliable," he said.
Immediately after declaring a "contingency," NASA's keep-calm term for an emergency, administrators ordered workers Saturday morning to secure all documentary evidence of the accident, from maintenance logs to flight data files and handwritten notes of ground controllers.
"It's going to take days and weeks to put it together and see what we have," Dittemore said.
Hundreds of people have been mobilized under the direction of the Federal Emergency Management Agency to identify, document and collect the thousands of pieces of debris on the ground and in lakes and reservoirs.
Ranging from chunks the size of a compact car to individual bolts, they will be transported to Barksdale Air Force Base in Shreveport, La., for cataloging and analysis.
Body parts - officials said remains of all seven astronauts had been found - will be documented before being transported as families desire for burial or cremation.
Much of the work will be aimed at putting together a minutely detailed, moment-by-moment account of what happened. The Challenger investigation broke down that disaster to each thousandth of a second.
Such a timeline will draw on the masses of telemetry data on temperature, pressure, speed, flap positions and many other indicators that Columbia sent to Mission Control in the last minutes of the flight.
Those sophisticated computer records - including a mix of accurate and erratic data in the last 32 seconds that NASA has yet to analyze - will be combined with videos sent in by Texans who ran outside to capture the fiery descent on film.
Dittemore said 600 people had called to offer videotapes and other bits of information, and NASA had received about 200 e-mails, half of them including digital photographs.
"All that information is being pored over right now," he said.
Another focus will be the moment 80 seconds after takeoff Jan. 16 when foam insulation from the external fuel tank broke off and struck the shuttle's left wing. NASA technicians will re-examine video of the mishap, trying to assess whether the light but fast-moving foam might have done serious damage to the insulating tiles.
Foam being studied
NASA dispatched a team of investigators yesterday to study the foam at a NASA-Lockheed Martin manufacturing plant in New Orleans where shuttle tanks are manufactured.
Officials said chunks of foam have broken loose from the same part of the shuttle fuel tank on at least three flights - Atlantis in October, and Columbia on a 1997 launch and on Jan. 16.
In 1997, a NASA status report found that "while investigations into the cause of Columbia's unusual tile damage continue, managers hope the additional work will reduce the possibility of external tank foam debris contributing to shuttle tile damage."
Burnett said that investigating a major accident is like backtracking to find the first thing that went wrong.
"You look for the parts that came off first," he said.
To determine which pieces fell off the shuttle first, said Macidull, NASA investigators will have to combine data on where the parts were found with data on wind direction and speed. In some cases, it may be necessary to study the aerodynamic properties of a particular scrap, to determine whether it would glide or plummet to the ground.
A piece of metal from Columbia can yield a number of clues about what made the shuttle come apart.
Tim Weihs, a metallurgist and professor of material sciences and engineering at the Johns Hopkins University the way a metal shard from the Columbia is fractured or burned, and any residues on it, may show whether the shuttle was broken apart by an explosion, pressure or heat.
Analyzing aluminum from the Columbia's hull, for instance, might show when the insulating tiles came off, Weihs said.
In examining individual pieces of metal, scientists may be able to determine whether a piece broke because of extended wear or sudden force. Metal that wears out shows "fatigue striations," Macidull said.
After the Challenger explosion, NASA recovered about 80 percent of the shuttle and reassembled it at the Kennedy Space Center in Florida.
But Burnett and others noted yesterday that unlike the Challenger, which exploded during its launch, the Columbia came apart 39 miles from Earth and its remnants are scattered over a 500-mile area.
Challenger included an intact crew compartment and other huge chunks, some far larger than anything recovered from Columbia so far.
In addition to examining metal debris, Dittemore said, investigators may look at the wiring in the left wheel well of one of the remaining shuttles while it is being overhauled by maintenance crews. That may provide clues to help explain the peculiar combination of sensor failures and overheating aboard Columbia.
Investigators are likely to do close analysis of the insulating tiles, more than 20,000 of which were custom-made to protect the shuttle's fragile aluminum shell from the intense heat of re-entry, which can reach 3,000 degrees Fahrenheit on the wings and nose.
Controversy has followed the tiles almost from the origin of the shuttle program. While they have a remarkable ability to dissipate heat, they are highly susceptible to damage and can be dented by modest pressure from a fingernail.
During many shuttle flights, the orbiters have lost some tiles on the way through the atmosphere. The resulting damage has never been catastrophic, though technicians have often found scorched aluminum beneath the missing tiles.
In 2001, looking over the space shuttle Discovery after a flight, NASA repair workers found one missing tile and counted 153 dents and gouges, 24 of them an inch or larger.
Dittemore defended the tile insulators, saying they have peformed well on 20 years of shuttle missions.
"I would say the tile system of insulation has performed wonderfully," he said. While NASA is exploring new technologies, they are not looking to replace them, he said.
Uncertain destination
Hotz, the former Aviation Week editor, noted that the precise cause of the Challenger's demise was not discovered for months. Investigators knew an O-ring damaged by cold had allowed smoke to shoot out of a solid-rocket booster on takeoff - and discovered documents dating to 1977 raising questions about the O-rings.
But they couldn't figure out why the smoke then disappeared for a full minute before reappearing in a jet of flame that sparked the disaster.
Finally, he said, the presidential commission concluded that silicon from the propellant had formed a glass-like covering over the leaky O-ring. The glass coating was then broken by wind shear, Hotz said.
"You never know where the trail's going to lead," he said.
For the Challenger investigation and some major airliner disasters, including the TWA Flight 800 crash off New York and the airliner crash over Lockerbie, Scotland, major parts of the aircraft were reconstructed.
But Burnett said it may not be possible to reconstruct any significant portion of the Columbia because it came apart so high in the air and was moving so fast that it scattered debris widely.
"We've never had a breakup 40 miles up, so the trajectory of the debris field is larger than ever before," he said. "There are pieces that may not be found for years."
"It's a daunting task, because the evidence is spread over 500 miles," said John C. Macidull, an engineer and former Navy test pilot who was a lead investigator of the Challenger disaster in 1986. "But it is possible."
One critical task is establishing the sequence of events leading to the breakup of the 90-ton craft 39 miles over Texas.
"You usually work backwards from the pieces that flew off first, to the cause of the initial failure," said Jim Burnett, who was chairman of the National Transportation Safety Board when the Challenger blew apart shortly after launch.
In an investigation that is likely to take months, everything from amateur videos of the smoking debris arcing toward earth to decades-old paperwork documenting the design of shuttle parts is likely to be scrutinized by scientists.
The investigators will use microscopic examination and chemical tests on metal scraps to determine where they originated on the shuttle and how they broke off. They will examine critical parts of the remaining three shuttles, trying to locate design weaknesses.
"You've got to look at everything," said Robert B. Hotz, who was editor of Aviation Week for 25 years and later served on the presidential commission that investigated the Challenger. "When you start out on an accident investigation you don't know where it's going to lead."
But both NASA officials and outside experts emphasized that the quest for answers in the tragedy is just beginning. It's important not to leap to any single conclusion, thus closing out other possibilities, they said.
"The first thing is to gather materials, recollections, data and imagery," said James E. Oberg, who worked at Mission Control for 22 years and is now an aerospace author and consultant. "It can be damaging to jump too quickly to any hypothesis."
Ron Dittemore, NASA's shuttle program manager, offered a similar caveat even as he told a press conference last night what he knew.
"First reports are notoriously unreliable," he said.
Immediately after declaring a "contingency," NASA's keep-calm term for an emergency, administrators ordered workers Saturday morning to secure all documentary evidence of the accident, from maintenance logs to flight data files and handwritten notes of ground controllers.
"It's going to take days and weeks to put it together and see what we have," Dittemore said.
Hundreds of people have been mobilized under the direction of the Federal Emergency Management Agency to identify, document and collect the thousands of pieces of debris on the ground and in lakes and reservoirs.
Ranging from chunks the size of a compact car to individual bolts, they will be transported to Barksdale Air Force Base in Shreveport, La., for cataloging and analysis.
Body parts - officials said remains of all seven astronauts had been found - will be documented before being transported as families desire for burial or cremation.
Much of the work will be aimed at putting together a minutely detailed, moment-by-moment account of what happened. The Challenger investigation broke down that disaster to each thousandth of a second.
Such a timeline will draw on the masses of telemetry data on temperature, pressure, speed, flap positions and many other indicators that Columbia sent to Mission Control in the last minutes of the flight.
Those sophisticated computer records - including a mix of accurate and erratic data in the last 32 seconds that NASA has yet to analyze - will be combined with videos sent in by Texans who ran outside to capture the fiery descent on film.
Dittemore said 600 people had called to offer videotapes and other bits of information, and NASA had received about 200 e-mails, half of them including digital photographs.
"All that information is being pored over right now," he said.
Another focus will be the moment 80 seconds after takeoff Jan. 16 when foam insulation from the external fuel tank broke off and struck the shuttle's left wing. NASA technicians will re-examine video of the mishap, trying to assess whether the light but fast-moving foam might have done serious damage to the insulating tiles.
Officials said chunks of foam have broken loose from the same part of the shuttle fuel tank on at least three flights - Atlantis in October, and Columbia on a 1997 launch and on Jan. 16.
In 1997, a NASA status report found that "while investigations into the cause of Columbia's unusual tile damage continue, managers hope the additional work will reduce the possibility of external tank foam debris contributing to shuttle tile damage."
Burnett said that investigating a major accident is like backtracking to find the first thing that went wrong.
"You look for the parts that came off first," he said.
To determine which pieces fell off the shuttle first, said Macidull, NASA investigators will have to combine data on where the parts were found with data on wind direction and speed. In some cases, it may be necessary to study the aerodynamic properties of a particular scrap, to determine whether it would glide or plummet to the ground.
A piece of metal from Columbia can yield a number of clues about what made the shuttle come apart.
Tim Weihs, a metallurgist and professor of material sciences and engineering at the Johns Hopkins University the way a metal shard from the Columbia is fractured or burned, and any residues on it, may show whether the shuttle was broken apart by an explosion, pressure or heat.
Analyzing aluminum from the Columbia's hull, for instance, might show when the insulating tiles came off, Weihs said.
In examining individual pieces of metal, scientists may be able to determine whether a piece broke because of extended wear or sudden force. Metal that wears out shows "fatigue striations," Macidull said.
After the Challenger explosion, NASA recovered about 80 percent of the shuttle and reassembled it at the Kennedy Space Center in Florida.
But Burnett and others noted yesterday that unlike the Challenger, which exploded during its launch, the Columbia came apart 39 miles from Earth and its remnants are scattered over a 500-mile area.
Challenger included an intact crew compartment and other huge chunks, some far larger than anything recovered from Columbia so far.
In addition to examining metal debris, Dittemore said, investigators may look at the wiring in the left wheel well of one of the remaining shuttles while it is being overhauled by maintenance crews. That may provide clues to help explain the peculiar combination of sensor failures and overheating aboard Columbia.
Investigators are likely to do close analysis of the insulating tiles, more than 20,000 of which were custom-made to protect the shuttle's fragile aluminum shell from the intense heat of re-entry, which can reach 3,000 degrees Fahrenheit on the wings and nose.
Controversy has followed the tiles almost from the origin of the shuttle program. While they have a remarkable ability to dissipate heat, they are highly susceptible to damage and can be dented by modest pressure from a fingernail.
During many shuttle flights, the orbiters have lost some tiles on the way through the atmosphere. The resulting damage has never been catastrophic, though technicians have often found scorched aluminum beneath the missing tiles.
In 2001, looking over the space shuttle Discovery after a flight, NASA repair workers found one missing tile and counted 153 dents and gouges, 24 of them an inch or larger.
Dittemore defended the tile insulators, saying they have peformed well on 20 years of shuttle missions.
"I would say the tile system of insulation has performed wonderfully," he said. While NASA is exploring new technologies, they are not looking to replace them, he said.
But they couldn't figure out why the smoke then disappeared for a full minute before reappearing in a jet of flame that sparked the disaster.
Finally, he said, the presidential commission concluded that silicon from the propellant had formed a glass-like covering over the leaky O-ring. The glass coating was then broken by wind shear, Hotz said.
"You never know where the trail's going to lead," he said.
For the Challenger investigation and some major airliner disasters, including the TWA Flight 800 crash off New York and the airliner crash over Lockerbie, Scotland, major parts of the aircraft were reconstructed.
But Burnett said it may not be possible to reconstruct any significant portion of the Columbia because it came apart so high in the air and was moving so fast that it scattered debris widely.
"We've never had a breakup 40 miles up, so the trajectory of the debris field is larger than ever before," he said. "There are pieces that may not be found for years."