Fears the boots
Join Date: May 2003
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Flaws in space shuttle design: Reports
June 24, 2003
Washington: The board investigating the the Columbia disaster in which Indian born Kalpana Chawla and seven other astronauts perished has discovered "grave flaws" in the design of the space shuttle.
The list of problems include, a weak design in a device that catches heavy metal debris from the explosive separation of the shuttle's spent rocket boosters during ascent and hazardous fuel in the orbiter's auxiliary power units that, among other things, power the shuttle's flight controls, experts have told the panel probing the disaster.
Possile cracks in "Stoody balls" deep in the orbiter's main propulsion system could also have contributed to the disaster.
"When a space shuttle is launched, the heavy duty bolts and nuts that secure it firmly to do the launch pad are designed to explode and release the vehicle as it surges into the skiles with almost eight million pounds of thrust".
If one or more of sturdy fixtures fails to give, experts have told the board, the result could be a horrific conflagration that could kill the crew and send torn shuttle components cartwheeling off the launch pad, the investigation board headed by Admiral Harold W. Gehman said.
Meanwhile, the US space shuttle fleet could return to space as early as December, without any enormous time- consuming changes even before the independent panel probing the loss of shuttle Columbia submits its report, media reports said here today. PTI TVP SPC 06241827 D (REOP FES90)
Engineers found cracks in one of the "stoody balls" last year. Though NASA engineers concluded that cracks would pose no risk investigators have questioned the findings.
The investigation board has concluded that a suitcase-size piece of foam flew off the shuttle's external tank and struck the left wing during liftoff, causing damage that allowed superheated planes to destroy the spaceship during reentry.
The panel has also been harshly critical of NASA's decision-making culture, including a creeping acceptance of the foam strikes as "routine," even though they violated design specifications, the Washington Post said.
The board does not plan to release a final report before late July. However, it has issued some preliminary recommendations. Its members have discussed at least some of the issues already, it said.
According to shuttle records reviewed during a Columbia liftoff in 1992, one of the hold-down devices did fail to release. The hardware stayed attached to a booster as it lifted off and tore a piece of material from the booster's base.
Air Force Major General John Barry, a member of the investigation board said that the board's inquiry revealed an engineering "integration" problem among the NASA facilities responsible for the various pieces of it.
In a review of radar images, investigators discovered that a piece of debris--possibly either a 40-pound chunk of a broken bolt or the 11-pound container designed to capture it--flew off Columbia as the boosters separated just over two minutes after its January 16 liftoff.
(CBS/AP) The panel probing the shuttle Columbia disaster has uncovered several problems that could imperil the three remaining spacecraft in the shuttle fleet, a newspaper reports.
The flaws include struts connecting the shuttle to the launch pad that are supposed to separate on ignition, but sometimes do not; dangerous fuel that powers the shuttle's steering system; and metal balls that are used to protect the shuttle's internal piping during take-off, according to The Washington Post.
The board led by Admiral Harold W. Gehman does not believe these problems contributed to the Feb.1 accident that killed all seven astronauts aboard Columbia. While the panel is not expected to release a final report until next month, it believes a fragment of the foam that insulates the external fuel tank broke off and struck the body of the shuttle, exposing a wing to excessive heat when Columbia reentered the earth's atmosphere.
But the newly discovered flaws could pose risks to future flights by the shuttles Atlantis, Discovery or Endeavour.
Two weeks ago, the panel noted another problem that could harm the remaining shuttles: weakness in the "bolt catchers" meant to secure 40-pound fragments of explosive bolts that fall away when the shuttle's booster rockets separate from the craft.
The bolt catcher used on Columbia was made by a new manufacturer and records showed it had not been tested dynamically. When board investigators conducted a test on the device, it failed.
According to The Post, Gehman's team is looking for possible new problems as part of a broad review that goes beyond the Columbia disaster to look at the shuttle program as a whole, especially its management culture.
The problem with the struts that connect the shuttle to the launch pad is potentially the most serious. The two large rocket boosters that lift the shuttle into orbit cannot be shut down once fired, so if the craft ever failed to lift off, a catastrophic explosion would occur on the launch pad.
The rockets are connected to the launch pad by struts that are supposed to blow off of time for liftoff. But sometimes they fail — in October, the primary signal to one of the bolts failed. A backup signal averted disaster. In a 1992 launch of Columbia, The Post found, one of the bolts never blew and part of the booster was ripped off as it rocketed off the launcher.
The fuel used to power systems of hydraulic controls is flammable and caustic, the panel found, which could lead to accidents.
The steel balls that separate tubes inside the shuttle, and protects them from snapping against each other during rough flight, sometimes crack. That could lead to dangerous leaks, the panel has found.
At the instant of a fiery liftoff, an array of finger-size explosives is supposed to shatter the steel nuts that anchor a space shuttle to its launchpad.
But for shuttle Atlantis, something went very wrong last year. Detonation charges planted in the eight hold-down nuts -- each as big as a saucepan and weighing nearly 10 pounds -- failed.
Separate firing signals did trigger backup explosives, and Atlantis thundered into orbit. But ground personnel -- who never could find the cause of the failure -- were left chilled by the specter of anchors not letting go of a shuttle that has unleashed 7.8 million pounds of launch thrust.
"Some people still involved in the program confided to me that they have been awakened in the night with nightmarish pictures of the vehicle cartwheeling off the pad," said Bill Heink, who retired in 2000 as site director of The Boeing Co. shuttle operations at Kennedy Space Center. "The potential is there."
Hold-down anchors are only one example of persistent defects and breakdowns that have plagued the shuttle since the first launch in 1981.
An Orlando Sentinel review of NASA's hazard-evaluation studies and nearly 2,000 malfunction reports from the 113 shuttle flights found a half-dozen hardware systems -- all critical to successful launch, orbit and landing -- that have repeatedly faltered or failed during flight. In many instances, they have been treated and accepted in much the same fashion that NASA reacted to ongoing flaws that doomed Challenger and Columbia.
The systems aren't thought to be as inherently dangerous as, for example, the shuttle's main engines, which are considered most likely to trigger catastrophe.
But the foam that insulates the shuttle's external fuel tank -- and which regularly ripped loose from the tank and pelted the orbiters -- wasn't considered inherently dangerous either.
Even after engineers determined Columbia had been struck by a chunk of foam shortly after liftoff, NASA did not think it could do enough damage to lead to the destruction of the shuttle.
The agency was wrong.
Now, as NASA prepares to return the three remaining shuttles to flight, the Columbia Accident Investigation Board -- which expects to release its final report Aug. 26 -- is asking, in effect: What could be the next foam disaster?
Board Chairman Harold Gehman Jr. said he has told his investigators: "If these flaws are out there . . . tell me what the next one is."
Among the possibilities, according to Sentinel research:
Entire banks of the orbiter's 44 jet thrusters, needed for precise maneuvers in space, must be shut off because of various malfunctions during most flights. In 1995, damaged thrusters aboard Discovery spewed hazardous fuel as it approached the Mir space station, much to the alarm of the Russians inside.
Electric arcing from damaged wire caused a shutdown of computers that controlled two of three main engines aboard Columbia in 1999. A backup system took over. But despite subsequent studies suggesting damage and deterioration of aging wiring, not all of it has been replaced.
NASA relies on exploding nuts and bolts to trigger the separation of the solid rocket boosters and external fuel tank from the shuttle. But devices designed to capture this pyrotechnic debris have repeatedly failed -- and possibly during Columbia's last flight -- raising the potential of chunks of metal ripping into the body of the shuttle.
At least one of the three auxiliary-power units, which provide hydraulic pressure needed to steer the orbiter, has had problems in most flights, usually because of overheating. Some have even caught fire during landing. NASA engineers were so worried that they commissioned in the late 1990s a major redesign of the power units -- but pulled the plug because of soaring costs.
NASA has been unable to prevent episodes of highly explosive hydrogen gas -- which leaks from the external tank, shuttle and ground systems -- accumulating beneath the shuttle as it sits on the launchpad. High concentrations of the gas have prompted several scrubbed launches.
NASA engineers and the flight-hazard reviews acknowledge that each has the potential to fail in ways that lead to a major accident. The investigation board has asked the agency for details on several of those issues.
And like the foam that led to Columbia's breakup over Texas on Feb. 1, and the booster joint O-rings that doomed Challenger in 1986, all six systems have defied NASA's various efforts to fix them.
When a malfunction occurs, NASA often replaces parts and may even do extensive troubleshooting. But given limited budgets and the aging technology of the shuttles, the agency often has been unable or unwilling to come up with permanent solutions.
Instead, NASA documents show, the space agency has accepted the risks, often thinking that backup systems can compensate for breakdowns.
"It's fair to say they got comfortable with these," said Duke University Professor Alex Roland, a former NASA historian who follows the space agency. "They were rather just crossing their fingers and hoping. And if it didn't do what they once feared it would do, they accepted that and just moved on."
The Sentinel asked NASA for more than a week to provide engineers, executives or documents to explain how the agency has handled the problems. NASA responded by passing the requests to United Space Alliance, the private company that runs day-to-day shuttle operations. A NASA spokesman also said the company had indicated that "it will take a great deal of time" to respond.
Call for answers
To critics of NASA, the agency's willingness to continue flying without fixing these problems is part of a failed organizational culture that must be fixed if the shuttle is to return safely to flight. NASA engineers, they say, are too willing to assume the best, in order to keep the shuttle flying and control costs.
"The answer to this is to go back and try to understand what you don't understand," said John Pike, director of GlobalSecurity.org, a space-policy think tank. "You have to go back and look at what parts of your understanding on the shuttle are based on assumptions, and which ones are based on conclusions."
Since the Columbia disaster, NASA and the Columbia investigation board have been looking for problems that could doom future shuttle flights. The task is formidable.
A shuttle has 2.5 million parts. It accelerates to 17,400 mph in 8.5 minutes, withstanding temperatures ranging from the minus-423 degrees of liquid hydrogen fuel to the 6,000-plus degrees within engine combustion chambers. Then, after orbiting in the vacuum of space, it endures temperatures of up to 3,000 degrees on its way to landing on Earth.
Every mission brings its own set of problems, from malfunctioning toilets to a premature shutdown of main engines. NASA's reviews of these problems are outlined in so-called "in-flight anomaly" reports, released under the Freedom of Information Act.
Much to learn
The reports, which have drawn criticism for not tracking all major flight problems, chronicle how engineers progressively learned not to worry about the flaw that brought down Columbia.
Investigators have concluded that a 1.67-pound chunk of foam flew off the external tank nearly 82 seconds after liftoff and smashed a hole in the thermal armor along Columbia's left wing, allowing hot gases to penetrate and destroy the wing during re-entry. All seven crew members were killed.
Foam debris had damaged thermal armor in all 112 previous launches and twice ripped more than 500 "craters" in the silicate-based thermal tiles that line the orbiter's belly.
Shuttle engineers familiar with the troubled systems analyzed by the Sentinel say it's unlikely that their failures would lead to a disaster. But they also admit to previously saying the same thing about foam debris.
Arguably, Columbia was a classic example of Murphy's Law: The chunk of foam was the largest ever known to have come off the tank. It fell off later than any previous piece, so it was moving faster -- about 500 mph in relation to the orbiter. And like none before it, the foam struck directly on the leading edge of the wing.
Robert "Hoot" Gibson, a retired astronaut who was commander during four of five missions he flew, describes it as "the 'golden BB' -- to think about the right chunk of foam coming loose at the right speed to hit the right place on the wing and knock a hole in it."
But as the thousands of anomalies during 22 years of flight prove, there is still a great deal about the shuttle that NASA engineers do not understand. And all it takes is a horribly perfect scenario, a terribly ideal sequence of events, to propel those unknowns into a chain reaction that no one thought possible until it was too late.
If fuel gums up jets,
they leak, steer poorly
When a shuttle reaches orbit and begins maneuvering in space, the question is not so much whether a steering jet will malfunction as it is how many will quit working, leak or both.
NASA has reported 117 of those failures in 84 missions, according to Sentinel analysis.
A shuttle has 44 of the jets, called thrusters, mounted in its nose and tail and pointed in various directions.
They work by combining hydrazine, a highly corrosive fuel, with an oxidizing chemical. The two ignite on contact, providing thrust that propels the orbiter through a turn, roll or other maneuver.
But the oxidizing chemical also eats away at the system's plumbing and leaves deposits of what NASA calls "metallic-nitrate contamination."
The stuff gums up the thrusters so they can't fire -- or they leak.
The failure of too many thrusters could leave astronauts unable to steer the shuttle. But NASA insists that's no concern, that there are more than enough thrusters to compensate for the failure of a few.
That belief was tested in 1995, when Discovery made the first approach to the Russian space station. Discovery's leaky thrusters -- one of them spouted a quart of oxidizer an hour -- alarmed Mir's cosmonauts because of the potential to cause station sensors to malfunction.
So Discovery approached only after main valves were closed, stopping the leaks but also disabling other thrusters.
Rudy Seiffer, a retired NASA deputy engineering director for shuttle systems at Kennedy Space Center, said a permanent fix would require extensive modifications. Instead, shuttle managers chose to remove failed thrusters for regular cleaning and maintenance at the agency's White Sands Test Facility in New Mexico.
"I didn't feel it was that a severe a problem," Seiffer said, who acknowledged he once thought the same of foam debris. ". . . But things go wrong."
Despite aging, arcing,
all wires weren't replaced
The orbiter's main systems, including avionics, computers and hydraulics, are linked by up to 157 miles of wiring, forming the shuttle's central nervous system.
Never was the importance of wiring more clear than during a July 1999 launch of Columbia, when nicked and exposed wiring caused electrical "arcing," shorting out a circuit five seconds after liftoff.
A pair of computers controlling two of Columbia's three main engines were knocked out. Backup computers took over, but the shuttle was a failure away from losing at least one engine -- and a possible emergency landing.
Engineers later suspected that a protruding screw nicked the wiring's Kapton insulation when technicians were servicing the orbiter. Kapton, prone to damage and susceptible to arcing, has been mostly banned from new U.S. military aircraft after suspected involvement in crashes.
The Columbia incident led to the grounding of the shuttle fleet for almost five months. Wiring inspections following the incident and during a maintenance overhaul of Columbia revealed anywhere from 1,677 "discrepancies" -- damaged, chafed or exposed Kapton -- on Discovery to 3,967 on Columbia. What's more, 1,704 feet of Columbia's wiring was inaccessible to inspectors, but NASA decided it could fly "as is" because of the low risk of damage, according to NASA documents obtained by the Sentinel.
A current overhaul of Discovery has turned up an additional 2,438 wiring problems, documents show.
"Damage to wiring or insulation and aging of insulation are a concern to the shuttle fleet," according to a March 2000 NASA advisory-panel report. It said "arcing" had been pointed out as a serious risk since 1991.
NASA reports show dozens of electrical problems during flights that were not explained by troubleshooting but were suspected to involve faulty wiring. Former shuttle managers say those reports do not reflect countless wiring problems discovered while the shuttles were being processed on the ground.
And a November 2001 study performed for Boeing suggested that 91 percent of Columbia's midbody wiring was "fully aged" and, as of September 2000, had an "expected remaining life" of less than two years. However, the company performing the study said a more extensive analysis was needed to confirm the results.
Still, the wiring wasn't replaced. And as NASA engineers ready Atlantis to return to flight next year, they've decided against a wire-by-wire inspection, sources said. In a separate matter, engineers have recommended separating redundant wiring in about 50 spots on the vehicle.
Bolts don't always release
cleanly during launch
Nightmares about the launchpad anchoring system are rooted in its many malfunctions -- on at least 16 flights during the shuttle's 22-year history, according to an analysis by the Sentinel. The problems varied from a computer warning that the explosives were primed to prematurely blow off the nuts -- which resulted in a scrubbed launch -- to many instances when the shuttle had to wrench itself free of one or several of the 3.5-inch-thick bolts used in the anchors.
Yet, despite the efforts of NASA engineers, the problem has neither been solved nor, as the Atlantis episode showed, clearly diagnosed.
So NASA has chosen to live with it -- and continue flying.
"I can tell you it just seemed to keep recurring and recurring and recurring," said Heink, the former site director of Boeing's shuttle operations at KSC. "And I never saw anything being done that really seemed to be resolving the problem. It is, indeed, a terribly significant concern."
During the countdown to blastoff, the 4.5 million-pound shuttle is held on the launchpad by just eight nut-and-bolt assemblies. And for 6.6 seconds, while the main engines rev up to more than 1.2 million pounds of thrust, it strains against the 3.5-inch-thick bolts.
Then the two solid rocket boosters fire -- and explosive charges simultaneously fragment the nuts atop the hold-down posts, allowing the shuttle to rise off the launchpad.
Like so much of what occurs in shuttle flight, the detonation of these "frangible" nuts is a choreography of brute force applied very precisely. During the launch of Atlantis in 1991, seven of the anchor nuts self-destructed as designed. But the firing of the explosives in the eighth was off ever so slightly -- just one-half of one-thousandth of a second.
That "skewed firing" prevented what should have been a clean separation -- the hold-down bolt gouged nearly a half-inch of steel out of the bolt-hole in the booster.
NASA engineers refer to that type of failure as a "stud hang-up"; they think the shuttle can launch safely even if all eight hold-down posts hang up -- as long as all of the nuts ultimately break apart.
So they've defined stud hang-ups as being "within the experience base" -- just like the insulating foam that routinely peeled off the external tank.
What NASA is doing about problems with the launchpad anchors is unclear, though accident investigators have said they are concerned about the system's reliability.
Price tag killed plan
to build safer units
Hydraulic steering -- during a shuttle's launch, and its re-entry -- depends on a unique source of power.
The "Auxiliary Power Unit" is not much larger than a microwave oven. Essentially a jet engine in a box, it has a turbine that spins 74,000 times a minute. It's run by a highly toxic fuel -- hydrazine -- and needs an elaborate array of hardware for lubrication, cooling, fuel handling and sensing trouble.
"It's remarkable the energy it puts out," said Bob Bucina, retired orbiter fluids and propulsion manager for The Boeing Co. at KSC. But that high performance comes with a cost.
"It's a big maintenance problem. Servicing takes a lot of time. And they're hazardous," he said.
In fact, NASA calculates that 30 percent of the overall risk of a shuttle catastrophe stems from the dangers of the three power units in each shuttle.
NASA managers have said their launch anxieties often began to peak as soon as the units started up, five minutes before liftoff. Two caught fire in a 1983 flight of Columbia, resulting in internal "detonation" and "minor shrapnel damage." More mundane malfunctions have occurred at least 170 times in 75 missions, according to the Sentinel analysis of NASA hazard reports.
Many of those problems stemmed from lubricant contamination or from failures of what serves as a radiator, a component called a "water-spray boiler" that often freezes up.
Those kinds of malfunctions don't directly jeopardize a shuttle but can lead to the shutdown of a unit. Shuttles can fly with two operating units. Flying with one will "result in dangerous degradation" of control, a NASA report states.
In the late 1990s, NASA decided it wanted units that could run on batteries to cut to 5 percent the risk of disaster because of power-unit failure. But initial cost estimates rose from $182 million to $667 million. NASA dropped the plan two years ago, having spent $70 million.
Tiny leaks can release
flammable, explosive gas
Hydrogen leaks on the launchpad -- events that have the potential to turn the shuttle into a fireball -- are one of NASA's biggest worries.
"Hydrogen is a very nasty thing," said Ted Sasseen, a retired chief shuttle engineer. Said another retired shuttle manager, Heink: "Nothing will stop a countdown faster than a hydrogen leak. You go in and find it."
The Sentinel analysis found that errors, malfunctions and leaks in the handling of hydrogen occurred at least 56 times, causing several launch delays.
Liquid hydrogen, at minus-423 degrees, can warp the seals at plumbing joints. And gaseous hydrogen can seap through even minuscule flaws. But a major leak from Atlantis in 2002 resulted in a cloud of accumulated hydrogen.
And tiny cracks found in a hydrogen fuel line of Atlantis last year -- the inspector was praised for having unusually sharp vision -- have heightened concerns that NASA has not stayed on top of potential disasters with the dangerous fuel.
NASA's primary response to leaks has been to install increasingly sophisticated gas-detection systems.
Containers don't always
catch all pieces from bolts
Accident investigators disclosed in June that half of an explosive bolt used to attach one of Columbia's solid rocket boosters to the external tank may have burst through its "bolt-catcher" nearly two minutes after launch Jan. 16.
Radar recorded the debris sailing away from Columbia. A hit by the bolt section, which weighed 40 pounds, would have been devastating.
While this was the first suspected failure of this particular bolt-catcher, the problem of uncontrolled pyrotechnic debris isn't new.
Among a number of events, pieces of explosive nuts that attach external-tank fuel lines to the shuttle have escaped from capture containers eight times.
The risk is that the metal fragments could jam covers -- called "umbilical doors" -- that must be closed over the fuel-tank-attachment ports to protect against the searing heat of re-entry. Pieces of shattered nuts have dropped onto the runway after those doors were opened.
According to a NASA analysis, "The probability of a fragment preventing ET door closure is considered remote."
NASA's inability to solve ongoing problems with shuttles opens the door to the next tragedy in the space program, critics say.
American University Professor Howard McCurdy, who has written several books about the nation's space program, said he is disturbed by how NASA has allowed repeated problems to become accepted as routine.
"The question is what's going to be the next one," he said.