| Space Shuttle Columbia Disaster |
Article Index for Space Shuttle |
Website Links For Space Shuttle |
Information AboutSpace Shuttle Columbia Disaster |
|
News to report Columbia explosion by Breaking News.]] The Space Shuttle ''Columbia'' disaster occurred on February 1 , 2003 , when the Space Shuttle ''Columbia'' disintegrated over Texas during Re-entry into the Earth's Atmosphere , with the loss of all seven crew, shortly before concluding its 28th mission, STS-107 . The loss of the ''Columbia'' was caused by damage sustained during launch when a piece of foam insulation the size of a small briefcase and known as the ''Left Bipod Foam Ramp'' broke off the Main Propellant Tank under the Aerodynamic forces of launch. The debris struck the Leading Edge of the left wing on the number 8 Reinforced Carbon-carbon (RCC) tile, damaging the Shuttle's thermal protection system (TPS). While ''Columbia'' was still in orbit, some engineers suspected damage, but NASA managers limited the investigation on the grounds that little could be done even if problems were found. NASA's Shuttle safety regulations stated that external tank foam shedding and subsequent debris strikes upon the Shuttle itself were safety issues that needed to be resolved before a launch was cleared, but launches were often given the go-ahead as engineers unsuccessfully studied the foam shedding problem. The majority of Shuttle launches recorded such foam strikes and thermal tile scarring in violation of safety regulations. During re-entry of STS-107, the damaged area allowed the hot gases to penetrate and destroy the internal wing structure,1 eventually causing the in-flight breakup of the vehicle. A massive ground search in parts of Texas, Louisiana and Arkansas recovered crew remains and many vehicle fragments. The Columbia Accident Investigation Board 's recommendations addressed both technical and organizational issues. The Space Shuttle Program was set back over two years by the disaster, a delay comparable only to that resulting from the ''Challenger'' Disaster . CREW . L to R: Brown, Husband, Clark, Chawla, Anderson, McCool, Ramon.]]
DEBRIS STRIKE DURING LAUNCH Despite its designation as the 107th Space Shuttle mission, STS-107 was actually the 113th to launch. It had been delayed 18 times over the two years from its original launch date of 11 January 2001 to its actual launch date of 16 January 2003 . A well-publicized launch delay due to cracks in the shuttle's propellant distribution system occurred one month before a 19 July 2002 launch date, but the Columbia Accident Investigation Board (CAIB) determined that this delay had nothing to do with the catastrophic failure six months later. The Left Bipod Foam Ramp is an approximately three-foot (one-meter) piece made entirely of foam, as opposed to being a metal ramp that is merely coated with foam. As such, the foam, not normally considered to be a structural material, is required to bear some aerodynamic loads. Because of these special requirements, the casting-in-place and curing of the ramps may be performed only by a senior technician.2 Bipod Foam Ramps had fallen off on at least three previous flights, with at least one previous strike that caused no serious damage; NASA management came to refer to this phenomenon as "foam shedding." As with the O-ring erosions that ultimately doomed the ''Challenger'', NASA management became accustomed to these phenomena when no serious consequences resulted from these earlier episodes. This phenomenon became known as "normalization of deviance."3 Video taken during lift-off of STS-107 was routinely reviewed two hours later and revealed nothing unusual. The following day, higher-resolution film that had been processed overnight revealed that a piece of Insulation foam fell from the external fuel tank 81.9 seconds into the launch sequence and appeared to strike the shuttle's left wing, potentially damaging the thermal protection on the Space Shuttle. The exact location where the foam struck the wing could not be determined due to the low resolution of the tracking camera footage. FLIGHT RISK MANAGEMENT In a risk-management scenario similar to the Challenger disaster, NASA management failed to recognize the relevance of engineering concerns for safety. Two examples of this were failure to honor engineer requests for imaging to inspect possible damage, and failure to respond to engineer requests about status of astronaut inspection of the left wing. Engineering made three separate requests for Department Of Defense (DOD) imaging of the shuttle in orbit to more precisely determine damage. While the images were not guaranteed to show the damage, the capability existed for imaging of sufficient resolution to provide meaningful examination. In fact, the CAIB recommended subsequent shuttle flights be imaged while in orbit using ground-based or space-based Department Of Defense assets.4 NASA management did not honor the requests and in some cases intervened to stop the DOD from assisting. NASA's chief Thermal Protection System (TPS) engineer was concerned about left wing TPS damage and asked NASA management whether an astronaut would visually inspect it. NASA managers never responded. Throughout the risk assessment process, senior NASA managers were influenced by their belief that nothing could be done even if damage was detected, hence this affected their stance on investigation urgency, thoroughness and possible contingency actions. They decided to conduct a parametric "what-if" scenario study more suited to determine risk probabilities of future events, instead of inspecting and assessing the actual damage. The investigation report in particular singled out NASA manager Linda Ham for exhibiting this attitude.Columbia Accident Investigation Board, (2003) Volume 1, Chapter 6, p. 138. Chapter 6 (pdf); retrieved June 8, 2006 Much of the risk assessment hinged on damage predictions to the thermal protection system. These fall into two categories: damage to the silica tile on the wing lower surface, and damage to the Reinforced Carbon-carbon (RCC) leading-edge panels. Damage-prediction software, known as "Crater", was used to evaluate possible tile and RCC damage. The software predicted severe penetration of multiple tiles by the impact, but engineers downplayed this, believing that results showing that the software overstated damage from small projectiles meant that the same would be true of larger Spray-On Foam Insulation (SOFI) impacts. The program used to predict RCC damage was based on small ice impacts the size of cigarette butts, not larger SOFI impacts. Under 1 of 15 predicted SOFI impact paths, the software predicted an ice impact would completely penetrate the RCC panel. Engineers downplayed this, too, believing that impacts of the less dense SOFI material would result in less damage than ice impacts. In an e-mail exchange, NASA managers questioned whether the density of the SOFI could be used as justification for reducing predicted damage. Despite engineering concerns about the energy imparted by the SOFI material, NASA managers ultimately accepted the rationale to reduce predicted damage of the RCC panels from complete penetration to slight damage to the panel's thin coating.5 NASA managers felt a rescue or repair was impossible, so there was no point in trying to inspect the vehicle for damage while on orbit. However, the CAIB determined either a rescue mission or on-orbit repair, though risky, might have been possible had NASA verified severe damage within five days into the mission.67 Ultimately the NASA Mission Management Team felt there was insufficient evidence to indicate that the strike was an unsafe situation, so they declared the debris strike a "turnaround" issue (not of highest importance) and denied the requests for the Department Of Defense images. DESTRUCTION DURING RE-ENTRY The following is a timeline of ''Columbia's'' re-entry. The shuttle was scheduled to land at 9:16 a.m. EST.
radar over Texas and Louisiana .]] ]]
RESPONSE FROM THE PRESIDENT At 14:04 EST (19:04 UTC), a somber President George W. Bush addressed the United States: "This day has brought terrible news and great sadness to our country... The ''Columbia'' is lost; there are no survivors." Despite the disaster, the President assured Americans that the space program would continue: "The cause in which they died will continue. Our journey into space will go on."9 RECOVERY OF DEBRIS More than 2,000 debris fields, including human remains, were found in sparsely populated areas southeast of Dallas from Nacogdoches in East Texas , where a high amount of debris fell, to western Louisiana and the southwestern counties of Arkansas . NASA issued warnings to the public that any debris could contain hazardous chemicals, that it should be left untouched, its location reported to local Emergency Services or government authorities, and that anyone in unauthorized possession of debris would be prosecuted. Because of the widespread area, volunteer Amateur Radio operators accompanied the search teams to provide communications support.10 A group of small (1 mm adult) '') designed to study the effect of weightlessness on physiology. The researchers were able to recover some usable data. Debris Search Pilot Jules F. Mier Jr. and Debris Search Aviation Specialist Charles Krenek died in a helicopter crash that injured three others while they were contributing to the ground search effort. Some Texas residents recovered some of the debris, ignoring the warnings, and attempted to sell it on the Online Auction Site EBay , starting at $10,000. The auction was quickly removed, but auctions for Columbia merchandise such as programs, photographs and patches, went up dramatically in value immediately following the disaster, creating a surge of Columbia-related listings. Interest in Columbia items was nonexistent before then.13 ONBOARD VIDEO One item recovered from the debris field was a videotape recording made by the astronauts during the start of re-entry. This video was later made available on NASA's website . The video recording lasts for thirteen minutes and shows the flight crew astronauts conducting routine re-entry procedures and joking with each other, none of them giving any indication of a problem. The video shows the flight-deck crew putting on their gloves and passing the video camera around in order to take footage of plasma and flames visible outside the windows of the orbiter, and ends approximately four minutes prior to the start of the shuttle's disintegration. On normal flights, the recording would have continued through landing. According to the online introduction given by Scott Altman , the remainder of the tape was destroyed in the accident. INITIAL INVESTIGATION NASA Space Shuttle Program Manager Ron Dittemore reported that "The first indication was loss of temperature sensors and hydraulic systems on the left wing. They were followed seconds and minutes later by several other problems, including loss of tire pressure indications on the left main gear and then indications of excessive structural heating".14 Analysis of 31 seconds of telemetry data which had initially been filtered out because of data corruption within it showed the shuttle fighting to maintain its orientation, eventually using maximum thrust from its Reaction Control System jets. The focus of the investigation centered on the foam strike from the very beginning. Incidents of debris strikes from ice and foam causing damage during take-off were already well known, and had actually damaged orbiters, most noticeably during STS-45 , STS-27 , and STS-87 .15 Tile damage had also been traced to ablating insulating material from the cryogenic fuel tank in the past. The composition of the foam insulation had been changed in 1997 to exclude the use of Freon , a chemical that causes Ozone Depletion ; while NASA was exempted from legislation phasing out CFCs, the agency chose to change the foam nonetheless. This led to many statements linking the foam strike to environmental pressures. STS-107 used an older "lightweight tank" where the foam was sprayed on to the larger cylindrical surfaces using the newer no freon foam. However, the bipods were manufactured from BX-250 foam which was excluded from the EPA regulations and did use the original Freon formula. The composition change did not contribute to the accident. 16 POSSIBLE EMERGENCY PROCEDURES The CAIB determined that had NASA management acted in time, two possible contingency procedures were available: a rescue mission by shuttle '' Atlantis '', and an emergency Spacewalk to attempt repairs to the left wing thermal protection. Rescue The CAIB determined a rescue mission, though risky, might have been possible provided NASA management took action soon enough. Normally a rescue mission is not possible, due to the time required to prepare a shuttle for launch, and the limited consumables (power, water, air) of an orbiting shuttle. However, ''Atlantis'' was well along in processing for a March 1 launch, and ''Columbia'' carried an unusually large quantity of consumables due to an Extended Duration Orbiter (EDO) package. The CAIB determined that this would have allowed ''Columbia'' to stay in orbit until flight day 30 ( February 15 ). NASA investigators determined that ''Atlantis'' processing could have been expedited with no skipped safety checks for a February 10 launch. Hence if nothing went wrong there was a five day overlap for a possible rescue. Repair NASA investigators determined on-orbit repair by the shuttle astronauts was possible but risky, primarily due to the uncertain resiliency of the repair using available materials. ''Columbia'' did not carry the Canadarm, or Remote Manipulator System , which would normally be used for camera inspection or transporting a spacewalking astronaut to the wing. Therefore an unusual emergency EVA would have been required. While there was no astronaut EVA training for maneuvering to the wing, astronauts are always prepared for a similarly difficult emergency EVA – to close the external tank umbilical doors located on the orbiter underside. During launch these doors are open for the propellant feed lines from the external tank to supply the main engines in the orbiter tail. If they fail to close after jettisoning the external tank, it constitutes a thermal protection breach which would destroy the orbiter upon re-entry. This requires an emergency EVA to close them manually. Similar methods could have reached the shuttle left wing for inspection or repair. For the repair, the CAIB determined the astronauts would have to use tools and small pieces of titanium, or other metal, scavenged from the crew cabin. These heavy metals would help protect the wing structure and would be held in place during re-entry by a water-filled bag that had turned into ice in the cold of space. The ice and metal would help restore wing leading edge geometry, preventing a turbulent airflow over the wing and therefore keeping heating and burn-through levels low enough for the crew to survive re-entry and bail out before landing. Because the NASA team could not verify that the repairs would survive even a modified re-entry, the rescue option had a considerably higher chance of bringing ''Columbia'''s crew back alive. ''COLUMBIA'' ACCIDENT INVESTIGATION BOARD See Also: Columbia Accident Investigation Board Following protocols established after the loss of '' Challenger '', an independent investigating board was created immediately following the accident. The Columbia Accident Investigation Board, or CAIB, consisted of expert military and civilian analysts who investigated the accident in great detail. ''Columbia's'' flight data recorder was found near Hemphill, Texas on March 20 , 2003 . Unlike commercial jet aircraft, the space shuttles do not have flight data recorders intended for after-crash analysis. Rather the vehicle data is transmitted in real time to the ground via Telemetry . However, since ''Columbia'' was the first shuttle, it had a special flight data OEX (Orbiter EXperiments) recorder, designed to help engineers better understand vehicle performance during the first test flights. Even after these were completed, the recorder was never removed from ''Columbia'', and was still functioning. It records many hundreds of different Parameter s and contained very extensive logs of structural and other data which allowed the CAIB to reconstruct many of the events during the process leading to breakup. Investigators could often use the loss of signals from sensors on the wing to track how the damage progressed. This was correlated with forensic debris analysis conducted at Lehigh University and other tests to obtain a final conclusion about the probable events. On July 7 , 2003 foam impact tests were performed by Southwest Research Institute , which used a foam block of similar size, mass and speed to that which struck ''Columbia.'' It created a hole 41 cm by 42.5 cm (16.1 inches by 16.7 inches) in the protective RCC panel.17 The tests clearly demonstrated that a foam impact of the type ''Columbia'' sustained could seriously breach the protective RCC panels on the wing leading edge.18 On August 26 , the CAIB issued its report on the accident. The report confirmed the immediate cause of the accident was a breach in the leading edge of the left wing, caused by insulating foam shed during launch. The report also delved deeply into the underlying organizational and cultural issues that led to the accident. The report was highly critical of NASA's decision-making and risk-assessment processes. It concluded the organizational structure and processes were sufficiently flawed that compromise of safety was expected no matter who was in the key decision-making positions. An example was the position of Shuttle Program Manager, where one individual was responsible for achieving safety, timely launches and acceptable costs, which are often conflicting goals. The CAIB report found that NASA had accepted deviations from design criteria as normal when they happened on several flights and did not lead to fatal consequences. One of those was the conflict between a design specification stating the Thermal Protection System was not designed to withstand significant impact damage and the common occurrence of impact damage to it during flight. The board made recommendations for significant changes in processes and culture. MISCELLANEOUS ITEMS Fears of terrorism Despite some initial fears after announcement in the news that Columbia suffered explosion over Palestine (Texas) and that the addition of the first Israel i Astronaut to the crew had made the ''Columbia'' a more likely target for terrorists, there is no evidence to support any theory that terrorism was involved. In any case, security surrounding the launch and landing of the space shuttle had been increased to ward off any potential Terrorist attack.19 The Merritt Island launch facility, like all sensitive government areas, had increased security measures put in place in the wake of the September 11 Attack . Gordon Johndroe, spokesman for the United States Department Of Homeland Security , stated: "There is no information at this time that this was a terrorist incident." "Purple streak" image The '' San Francisco Chronicle '' reported that an amateur astronomer had taken a five-second exposure that appeared to show "a purplish line near the shuttle" during re-entry. Mysterious purple streak is shown hitting Columbia 7 minutes before it disintegrated February 5, 2003 Mysterious purple streak is shown hitting Columbia January 30, 2006 The CAIB report concluded that image was the result of "camera vibrations during a long-exposure".20 MEMORIALS On February 4 , 2003 , President George Bush and his wife Laura led a memorial service for the astronauts' families at the Lyndon B. Johnson Space Center . Two days later, Vice President Dick Cheney and his wife Lynne led official Washington and the rest of the nation in paying tribute at a similar service at Washington National Cathedral . During that service, singer Patti LaBelle sang "Way up There".21 On March 26 the United States House Of Representatives ' Science Committee approved funds for the construction of a memorial at Arlington National Cemetery for the STS-107 crew. A similar memorial was built at the cemetery for the last crew of Space Shuttle Challenger . On October 28 , 2003 , the names of the astronauts were added to the Space Mirror Memorial at the Kennedy Space Center Visitor Complex . The Houston Astros honored the crew by having seven simultaneous first pitches thrown by family and friends of the ''Columbia'' crew. For the National Anthem , 107 members of the NASA family, including flight controllers and others involved in ''Columbia’s'' final mission, carried a U.S. flag onto the field. In addition, the Astros wore the mission patch on their sleeves for the entire season.22 |
|
|