MISSION CONTROL CENTER COMMUNICATIONS

¶At 8:49 a.m. Eastern Standard Time (EI+289), the Orbiterʼs flight control system began steering a precise course, or drag profile, with the initial roll command occurring about 30 seconds later. At 8:49:38 a.m., the Mission Control Guidance and Procedures officer called the Flight Director and indicated that the "closed-loop" guidance system had been initiated. GNC:

¶The Maintenance, Mechanical, and Crew Systems (MMACS) officer and the Flight Director (Flight) had the following exchange beginning at 8:54:24 a.m. (EI+613).

¶MMACS: "Flight – MMACS." Flight: "Go ahead, MMACS." MMACS: MMACS: "FYI, Iʼve just lost four separate temperature

transducers on the left side of the vehicle, hydraulic return temperatures. Two of them on system one and MMACS: one in each of systems two and three."

¶Flight: "Four hyd [hydraulic] return temps?" MMACS: "To the left outboard and left inboard elevon." MMACS: Flight: "Okay, is there anything common to them? DSC

[discrete signal conditioner] or MDM [multiplexer- demultiplexer] or anything? I mean, youʼre telling me you lost them all at exactly the same time?" MMACS:

¶MMACS: "No, not exactly. They were within probably four or five seconds of each other." Flight: "Okay, where are those, where is that instrumentation located?" MMACS: "All four of them are located in the aft part of the

left wing, right in front of the elevons, elevon actua- tors. And there is no commonality."

¶Flight: "No commonality."

¶At 8:56:02 a.m. (EI+713), the conversation between the Flight Director and the MMACS officer continues:

¶Flight: "MMACS, tell me again which systems theyʼre for." MMACS: "Thatʼs all three hydraulic systems. Itʼs ... two of them are to the left outboard elevon and two of them

¶The Flight Director then continues to discuss indications with other Mission Control Center personnel, including the Guidance, Navigation, and Control officer (GNC).

¶Flight: "GNC – Flight." GNC: "Flight – GNC." Flight: "Everything look good to you, control and rates and everything is nominal, right?" GNC: "Controlʼs been stable through the rolls that weʼve

done so far, flight. We have good trims. I donʼt see anything out of the ordinary."

¶Flight: "Okay. And MMACS, Flight?" MMACS: "Flight – MMACS." Flight: "All other indications for your hydraulic system indications are good." MMACS: "Theyʼre all good. Weʼve had good quantities all the way across." Flight: "And the other temps are normal?" MMACS: "The other temps are normal, yes sir." Flight: "And when you say you lost these, are you saying

that they went to zero?" [Time: 8:57:59 a.m., EI+830] "Or, off-scale low?"

¶MMACS: "All four of them are off-scale low. And they were

all staggered. They were, like I said, within several seconds of each other."

¶Flight: "Okay."

¶At 8:58:00 a.m. (EI+831), Columbia crossed the New Mexico- Texas state line. Within the minute, a broken call came on the air-to-ground voice loop from Columbiaʼs commander, "And, uh, Hou …" This was followed by a call from MMACS about failed tire pressure sensors at 8:59:15 a.m. (EI+906).

¶MMACS: "Flight – MMACS." Flight: "Go." MMACS: "We just lost tire pressure on the left outboard and left inboard, both tires."

¶to the left inboard." Flight: "Okay, I got you." [continued on next page]

¶The Flight Director then told the Capsule Communicator (CAP- COM) to let the crew know that Mission Control saw the messages and that the Flight Control Team was evaluating the indications and did not copy their last transmission.

¶CAPCOM: "And Columbia, Houston, we see your tire pressure messages and we did not copy your last call." Flight: "Is it instrumentation, MMACS? Gotta be ..." MMACS: "Flight – MMACS, those are also off-scale low."

¶At 8:59:32 a.m. (EI+923), Columbia was approaching Dallas, Texas, at 200,700 feet and Mach 18.1. At the same time, another broken call, the final call from Columbiaʼs commander, came on the air-to-ground voice loop:

¶INCO: Commander: "Roger, [cut off in mid-word] …"

¶This call may have been about the backup flight system tire pressure fault-summary messages annunciated to the crew onboard, and seen in the telemetry by Mission Control personnel. An extended loss of signal began at 08:59:32.136 a.m. (EI+923). This was the last valid data accepted by the Mission Control computer stream, and no further real-time data updates occurred in Mission Control. This coincided with the approximate time when the Flight Control Team would expect a short-duration loss of signal during antenna switching, as the onboard communication system automatically reconfigured from the west Tracking and Data Relay System satellite to either the east satellite or to the ground station at Kennedy Space Center. The following exchange then took place on the Flight Director loop with the Instrumentation and Communication Office (INCO):

¶INCO: "Flight – INCO." Flight: "Go." INCO: "Just taking a few hits here. Weʼre right up on top of the tail. Not too bad."

¶The Flight Director then resumes discussion with the MMACS officer at 9:00:18 a.m. (EI+969).

¶Flight: "MMACS – Flight." MMACS: "Flight – MMACS." Flight: "And thereʼs no commonality between all these tire

pressure instrumentations and the hydraulic return instrumentations."

¶MMACS: "No sir, thereʼs not. Weʼve also lost the nose gear

down talkback and the right main gear down talkback."

¶Flight: "Nose gear and right main gear down talkbacks?" MMACS: "Yes sir."

¶At 9:00:18 a.m. (EI+969), the postflight video and imagery analyses indicate that a catastrophic event occurred. Bright flashes suddenly enveloped the Orbiter, followed by a dramatic change in the trail of superheated air. This is considered the most likely time of the main breakup of Columbia. Because the loss of signal had occurred 46 seconds earlier, Mission Control had no insight into this event. Mission Control continued to work the loss-of-signal problem to regain communication with Columbia:

¶INCO: "Flight – INCO, I didnʼt expect, uh, this bad of a hit on comm [communications]." Flight: "GC [Ground Control officer] how far are we from GC:

¶UHF? Is that two-minute clock good?" GC: "Affirmative, Flight."

¶GNC: "If we have any reason to suspect any sort of

controllability issue, I would keep the control cards handy on page 4-dash-13."

¶Flight: "Copy."

¶At 9:02:21 a.m. (EI+1092, or 18 minutes-plus), the Mission Control Center commentator reported, "Fourteen minutes to touchdown for Columbia at the Kennedy Space Center. Flight controllers are continuing to stand by to regain communications with the spacecraft."

¶Flight: "INCO, we were rolled left last data we had and you

were expecting a little bit of ratty comm [communications], but not this long?"

¶INCO: "Thatʼs correct, Flight. I expected it to be a little intermittent. And this is pretty solid right here." Flight: "No onboard system config [configuration] changes right before we lost data?" INCO: "That is correct, Flight. All looked good." Flight: "Still on string two and everything looked good?" INCO: "String two looking good."

¶The Ground Control officer then told the Flight Director that the Orbiter was within two minutes of acquiring the Kennedy Space Center ground station for communications, "Two minutes to MILA." The Flight Director told the CAPCOM to try another communications check with Columbia, including one on the UHF system (via MILA, the Kennedy Space Center tracking station):

¶CAPCOM: "Columbia, Houston, comm [communications] check." CAPCOM: "Columbia, Houston, UHF comm [communications] check."

¶At 9:03:45 a.m. (EI+1176, or 19 minutes-plus), the Mission Control Center commentator reported, "CAPCOM Charlie Hobaugh calling Columbia on a UHF frequency as it approaches the Merritt Island (MILA) tracking station in Florida. Twelve-and-a-half minutes to touchdown, according to clocks in Mission Control."

¶MMACS: "Flight – MMACS." Flight: "MMACS?" MMACS: "On the tire pressures, we did see them go erratic for

a little bit before they went away, so I do believe itʼs instrumentation."

¶Flight: "Okay."

¶The Flight Control Team still had no indications of any serious problems onboard the Orbiter. In Mission Control, there was no way to know the exact cause of the failed sensor measurements, and while there was concern for the extended loss of signal, the recourse was to continue to try to regain communications and in the meantime determine if the other systems, based on the last valid data, continued to appear as expected. The Flight Director told the CAPCOM to continue to try to raise Columbia via UHF:

¶CAPCOM: "Columbia, Houston, UHF comm [communications] check." CAPCOM: "Columbia, Houston, UHF comm [communications] check." GC: "Flight – GC." Flight: "Go." GC: "MILA not reporting any RF [radio frequency] at this time."

¶GNC: "Flight – GNC." Flight: "Go." [continued on next page]

¶[continued from previous page]

¶INCO: "Flight – INCO, SPC [stored program command]

just should have taken us to STDN low." [STDN is the Space Tracking and Data Network, or ground station communication mode]

¶Flight: "Okay." Flight: "FDO, when are you expecting tracking? " [FDO

is the Flight Dynamics Officer in the Mission Control Center]

¶FDO: "One minute ago, Flight." GC: "And Flight – GC, no C-band yet." Flight: "Copy." CAPCOM: "Columbia, Houston, UHF comm [communications] check." INCO: "Flight – INCO." Flight: "Go." INCO: "I could swap strings in the blind."

¶Flight: "Okay, command us over." INCO: "In work, Flight."

¶At 09:08:25 a.m. (EI+1456, or 24 minutes-plus), the Instrumentation and Communications Officer reported, "Flight – INCO, Iʼve commanded string one in the blind," which indicated that the officer had executed a command sequence to Columbia to force the onboard S-band communications system to the backup string of avionics to try to regain communication, per the Flight Directorʼs direction in the previous call.

¶GC: "And Flight – GC." Flight: "Go." GC: "MILAʼs taking one of their antennas off into a search mode [to try to find Columbia]." Flight: "Copy. FDO – Flight?" FDO: "Go ahead, Flight." Flight: "Did we get, have we gotten any tracking data?" FDO: "We got a blip of tracking data, it was a bad data

point, Flight. We do not believe that was the Orbiter [referring to an errant blip on the large front screen in the Mission Control, where Orbiter

tracking data is displayed.] Weʼre entering a search pattern with our C-bands at this time. We do not have any valid data at this time."

¶By this time, 9:09:29 a.m. (EI+1520), Columbiaʼs speed would have dropped to Mach 2.5 for a standard approach to the Kennedy Space Center.

¶Flight: "OK. Any other trackers that we can go to?" FDO: "Let me start talking, Flight, to my navigator."

¶At 9:12:39 a.m. (E+1710, or 28 minutes-plus), Columbia should have been banking on the heading alignment cone to line up on Runway 33. At about this time, a member of the Mission Control team received a call on his cell phone from someone who had just seen live television coverage of Columbia breaking up during re-entry. The Mission Control team member walked to the Flight Directorʼs console and told him the Orbiter had disintegrated.

¶Flight: "GC, – Flight. GC – Flight?" GC: "Flight – GC."

¶Flight: "Lock the doors."

¶Having confirmed the loss of Columbia, the Entry Flight Director directed the Flight Control Team to begin contingency procedures.

¶In order to preserve all material relating to STS-107 as evidence for the accident investigation, NASA officials impounded data, software, hardware, and facilities at NASA and contractor sites in accordance with the pre-existing mishap response plan.

¶At the Johnson Space Center, the door to Mission Control was locked while personnel at the flight control consoles archived all original mission data. At the Kennedy Space Center, mission facilities and related hardware, including Launch Complex 39-A, were put under guard or stored in secure warehouses. Officials took similar actions at other key Shuttle facilities, including the Marshall Space Flight Center and the Michoud Assembly Facility.

¶Within minutes of the accident, the NASA Mishap Investigation Team was activated to coordinate debris recovery efforts with local, state, and federal agencies. The team initially operated out of Barksdale Air Force Base in Louisiana and soon after in Lufkin, Texas, and Carswell Field in Fort Worth, Texas.

¶Debris Search and Recovery

¶On the morning of February 1, a crackling boom that signaled the breakup of Columbia startled residents of East Texas. The long, low-pitched rumble heard just before 8:00 a.m. Central Standard Time (CST) was generated by pieces of debris streaking into the upper atmosphere at nearly 12,000 miles per hour. Within minutes, that debris fell to the ground. Cattle stampeded in Eastern Nacogdoches County. A fisherman on Toledo Bend reservoir saw a piece splash down in the water, while a women driving near Lufkin almost lost control of her car when debris smacked her windshield. As 911 dispatchers across Texas were flooded with calls reporting sonic booms and smoking debris, emergency personnel soon realized that residents were encountering the remnants of the Orbiter that NASA had reported missing minutes before.

¶The emergency response that began shortly after 8:00 a.m. CST Saturday morning grew into a massive effort to decon- taminate and recover debris strewn over an area that in Texas alone exceeded 2,000 square miles (see Figure 2.7-1). Local fire and police departments called in all personnel, who began responding to debris reports that by late afternoon were phoned in at a rate of 18 per minute.

¶Within hours of the accident, President Bush declared East Texas a federal disaster area, enabling the dispatch of emergency response teams from the Federal Emergency Management Agency and Environmental Protection Agency. As the day wore on, county constables, volunteers on horseback, and local citizens headed into pine forests and bushy thickets in search of debris and crew remains, while National Guard units mobilized to assist local law- enforcement guard debris sites. Researchers from Stephen F. Austin University sent seven teams into the field with Global Positioning System units to mark the exact location of debris. The researchers and later searchers then used this data to update debris distribution on detailed Geographic

¶Information System maps.

¶Figure 2.7-1. The debris field in East Texas spread over 2,000 square miles, and eventually over 700,000 acres were searched.

¶Public Safety Concerns

¶From the start, NASA officials sought to make the public aware of the hazards posed by certain pieces of debris, as well as the importance of turning over all debris to the authorities. Columbia carried highly toxic propellants that maneuvered the Orbiter in space and during early stages of re-entry. These propellants and other gases and liquids were stored in pressurized tanks and cylinders that posed a danger to people who might approach Orbiter debris. The propellants, monomethyl hydrazine and nitrogen tetroxide, as well as concentrated ammonia used in the Orbiterʼs cooling systems, can severely burn the lungs and exposed skin when encountered in vapor form. Other materials used in the Orbiter, such as beryllium, are also toxic. The Orbiter also contains various pyrotechnic devices that eject or release items such as the Ku-Band antenna, landing gear doors, and hatches in an emergency. These pyrotechnic devices and their triggers, which are designed to withstand high heat and therefore may have survived re-entry, posed a danger to people and livestock. They had to be removed by personnel trained in ordnance disposal.

¶In light of these and other hazards, NASA officials worked with local media and law enforcement to ensure that no one on the ground would be injured. To determine that Orbiter debris did not threaten air quality or drinking water, the Environmental Protection Agency activated Emergency Response and Removal Service contractors, who surveyed the area.

¶Land Search

¶The tremendous efforts mounted by the National Guard, Texas Department of Public Safety, and emergency personnel from local towns and communities were soon over- whelmed by the expanding bounds of the debris field, the densest region of which ran from just south of Fort Worth, Texas, to Fort Polk, Louisiana. Faced with a debris field several orders of magnitude larger than any previous accident site, NASA and Federal Emergency Management Agency officials activated Forest Service wildland firefighters to serve as the primary search teams. As NASA identified the areas to be searched, personnel and equipment were furnished by the Forest Service.

¶Within two weeks, the number of ground searchers exceeded 3,000. Within a month, more than 4,000 searchers were flown in from around the country to base camps in Corsicana, Palestine, Nacogdoches, and Hemphill, Texas. These searchers, drawn from across the United States and Puerto Rico, worked 12 hours per day on 14-, 21-, or 30-day rotations and were accompanied by Global Positioning System-equipped NASA and Environmental Protection Agency personnel trained to handle and identify debris.

¶Based on sophisticated mapping of debris trajectories gathered from telemetry, radar, photographs, video, and meteoro- logical data, as well as reports from the general public, teams were dispatched to walk precise grids of East Texas pine brush and thicket (see Figure 2.7-2). In lines 10 feet apart, a distance calculated to provide a 75 percent probability of de- tecting a six-inch-square object, wildland firefighters scoured snake-infested swamps, mud-filled creek beds, and brush so thick that one team advanced only a few hundred feet in an entire morning. These 20-person ground teams systemati- cally covered an area two miles to either side of the Orbiterʼs ground track. Initial efforts concentrated on the search for human remains and the debris corridor between Corsicana, Texas, and Fort Polk. Searchers gave highest priority to a list of some 20 "hot items" that potentially contained crucial information, including the Orbiterʼs General Purpose Computers, film, cameras, and the Modular Auxiliary Data System recorder. Once the wildland firefighters entered the field, recovery rates exceeded 1,000 pieces of debris per day.

¶Figure 2.7-2. Searching for debris was a laborious task that used thousands of people walking over hundreds of acres of Texas and Louisiana.

¶After searchers spotted a piece of debris and determined it was not hazardous, its location was recorded with a Global Positioning System unit and photographed. The debris was then tagged and taken to one of four collection centers at Corsicana, Palestine, Nacogdoches, and Hemphill, Texas. There, engineers made a preliminary identification, entered the find into a database, and then shipped the debris to Kennedy Space Center, where it was further analyzed in a hangar dedicated to the debris reconstruction.

¶Air Search

¶Air crews used 37 helicopters and seven fixed-wing aircraft to augment ground searchers by searching for debris farther out from the Orbiterʼs ground track, from two miles from the centerline to five miles on either side. Initially, these crews used advanced remote sensing technologies, including two satellite platforms, hyper-spectral and forward-looking in- frared scanners, forest penetration radars, and imagery from Lockheed U-2 reconnaissance aircraft. Because of the densi-

¶igure 2.7-3. Tragically, a helicopter crash during the debris earch claimed the lives of Jules "Buzz" Mier (in black coat) and harles Krenek (yellow coat).

¶ty of the East Texas vegetation, the small sizes of the debris, and the inability of sensors to differentiate Orbiter material from other objects, these devices proved of little value. As a result, the detection work fell to spotter teams who visually scanned the terrain. Air search coordinators apportioned grids to allow a 50 percent probability of detection for a one- foot-square object. Civil Air Patrol volunteers and others in powered parachutes, a type of ultralight aircraft, also participated in the search, but were less successful than helicopter and fixed-wing air crews in retrieving debris. During the air search, a Bell 407 helicopter crashed in Angelina National Forest in San Augustine County after a mechanical failure. The accident took the lives of Jules F. "Buzz" Mier Jr., a contract pilot, and Charles Krenek, a Texas Forest Service employee, and injured three others (see Figure 2.7-3).

¶Water Search

¶The United States Navy Supervisor of Salvage organized eight dive teams to search Lake Nacogdoches and Toledo Bend Reservoir, two bodies of water in dense debris fields. Sonar mapping of more than 31 square miles of lake bottom identified more than 3,100 targets in Toledo Bend and 326 targets in Lake Nacogdoches. Divers explored each target, but in murky water with visibility of only a few inches, underwater forests, and other submerged hazards, they recovered only one object in Toledo Bend and none in Lake Nacogdoches. The 60 divers came from the Navy, Coast Guard, Environmental Protection Agency, Texas Forest Service, Texas Department of Public Safety, Houston and Galveston police and fire departments, and Jasper County Sheriffʼs Department.

¶Search Beyond Texas and Louisiana

¶As thousands of personnel combed the Orbiterʼs ground track in Texas and Louisiana, other civic and community groups searched areas farther west. Environmental organizations and local law enforcement walked three counties of California coastline where oceanographic data indicated a high probability of debris washing ashore. Prison inmates scoured sections of the Nevada desert. Civil Air Patrol units and other volunteers searched thousands of acres in New Mexico, by air and on foot. Though these searchers failed to find any debris, they provided a valuable service by closing out potential debris sites, including nine areas in Texas, New Mexico, Nevada, and Utah identified by the National Transportation Safety Board as likely to contain debris. NASAʼs Mishap Investigation Team addressed each of the 1,459 debris reports it received. So eager was the general public to turn in pieces of potential debris that NASA received reports from 37 U.S. states that Columbiaʼs re-entry ground track did not cross, as well as from Canada, Jamaica, and the Bahamas.

¶Property Damage

¶No one was injured and little property damage resulted from the tens of thousands of pieces of falling debris (see Chapter 10). A reimbursement program administered by NASA distributed approximately $50,000 to property owners who made claims resulting from falling debris or collateral damage from the search efforts. There were, however, a few close calls that emphasize the importance of selecting the ground track that re-entering Orbiters follow. A 600-pound piece of a main engine dug a six-foot-wide hole in the Fort Polk golf course, while an 800-pound main engine piece, which hit the ground at an estimated 1,400 miles per hour, dug an even larger hole nearby. Disaster was narrowly averted outside Nacogdoches when a piece of debris landed between two highly explosive natural gas tanks set just feet apart.

¶Debris Amnesty

¶The response of the public in reporting and turning in debris was outstanding. To reinforce the message that Orbiter debris was government property as well as essential evidence of the accidentʼs cause, NASA and local media officials repeatedly urged local residents to report all debris immediately. For those who might have been keeping debris as souvenirs, NASA offered an amnesty that ran for several days. In the end, only a handful of people were prosecuted for theft of debris.

¶Final Totals

¶More than 25,000 people from 270 organizations took part in debris recovery operations. All told, searchers expended over 1.5 million hours covering more than 2.3 million acres, an area approaching the size of Connecticut. Over 700,000 acres were searched by foot, and searchers found over 84,000 individual pieces of Orbiter debris weighing more than 84,900 pounds, representing 38 percent of the Orbiterʼs dry weight. Though significant evidence from radar returns and video recordings indicate debris shedding across California, Nevada, and New Mexico, the most westerly piece of confirmed debris (at the time this report was published) was the tile found in a field in Littleton, Texas. Heavier objects with higher ballistic coefficients, a measure of how far objects will travel in the air, landed toward the end of the debris trail in western Louisiana. The most easterly debris pieces, including the Space Shuttle Main Engine turbopumps, were found in Fort Polk, Louisiana.

¶Figure 2.7-4. Recovered debris was returned to the Kennedy Space Center where it was laid out in a large hangar. The tape on the floor helped workers place each piece near where it had been on the Orbiter.

¶The Federal Emergency Management Agency, which directed the overall effort, expended more than $305 million to fund the search. This cost does not include what NASA spent on aircraft support or the wages of hundreds of civil servants employed at the recovery area and in analysis roles at NASA centers.

¶The Importance of Debris

¶The debris collected (see Figure 2.7-4) by searchers aided the investigation in significant ways. Among the most important finds was the Modular Auxiliary Data System recorder that captured data from hundreds of sensors that was not telemetered to Mission Control. Data from these 800 sensors, recorded on 9,400 feet of magnetic tape, provided investigators with millions of data points, including temperature sensor readings from Columbiaʼs left wing leading edge. The data also helped fill a 30-second gap in telemetered data and provided an additional 14 seconds of data after the telemetry loss of signal.

¶Recovered debris allowed investigators to build a three-dimensional reconstruction of Columbiaʼs left wing leading edge, which was the basis for understanding the order in which the left wing structure came apart, and led investigators to determine that heat first entered the wing in the location where photo analysis indicated the foam had struck.

¶The citations that contain a reference to "CAIB document" with CAB or

¶CTF followed by seven to eleven digits, such as CAB001-0010, refer to a document in the Columbia Accident Investigation Board database maintained by the Department of Justice and archived at the National Archives.

¶The primary source document for this process is NSTS 08117,

¶Requirements and Procedures for Certification and Flight Readiness.

¶CAIB document CTF017-03960413.²² before the 1986 Challenger accident NASA adopted an alternate Space For detailed discussions of the origins of the Space Shuttle, see Dennis R. Shuttle mission numbering scheme, this report uses the original STS flight Jenkins, Space Shuttle: The History of the National Space Transportation designations. System – The First 100 Missions (Cape Canaveral, FL: Specialty Press, 12 2001); T. A. Heppenheimer, The Space Shuttle Decision: NASAʼs Search President Reaganʼs quote is contained in President Ronald Reagan, for a Reusable Space Vehicle, NASA SP-4221 (Washington: Government "Remarks on the Completion of the Fourth Mission of the Space Shuttle Printing Office, 1999; also published by the Smithsonian Institution Press, Columbia," July 4, 1982, p. 870, in Public Papers of the Presidents of the 2002); and T. A. Heppenheimer, Development of the Space Shuttle, United States: Ronald Reagan (Washington: Government Printing Office, 1972-1981 (Washington: Smithsonian Institution Press, 2002). Much of 1982-1991). The emphasis noted is the Boardʼs. the discussion in this section is based on these studies. 13 "Pricing Options for the Space Shuttle," Congressional Budget Office National Commission on Space, Pioneering the Space Frontier: An Exciting Vision of Our Next Fifty Years in Space, Report of the National Commission on Space (Bantam Books, 1986), p. 2. Guidelines per NASA Policy Guideline 8621.Show full note

¶Statement of Daniel S. Goldin, Administrator, National Aeronautics and

¶Space Administration, before the Subcommittee on VA-HUD-Independent

¶Agencies, Committee on Appropriations, House of Representatives,

¶March 31, 1998. CAIB document CAB048-04000418.³³ See John M. Logsdon, "The Space Shuttle Program: A Policy Failure?" Report, 1985. Science, May 30, 1986 (Vol. 232), pp. 1099-1105 for an account of this 14 The quote is from page 2 of the We Deliver brochure, reproduced in decision process. Most of the information and quotes in this section are Exploring the Unknown Volume IV, p. 423. taken from this article. 15 NASA Johnson Space Center, "Technology Influences on the Space President George H. W. Bush, "Remarks on the 20th Anniversary of the Apollo 11 Moon Landing," Washington, D.C., July 20, 1989.Show full note

¶Roberta L. Gross, Inspector General, NASA, to Daniel S. Goldin,

¶Administrator, NASA, "Assessment of the Triana Mission, G-99-013, Final

¶Report," September 10, 1999. See in particular footnote 3, concerning

¶Although there is more volume of liquid hydrogen in the External Tank, liquid hydrogen is very light and its slosh effects are minimal and are generally ignored. At launch, the External Tank contains approximately

¶1.4 million pounds (140,000 gallons) of liquid oxygen, but only 230,000 pounds (385,000 gallons) of liquid hydrogen.⁵⁵ Heppenheimer, The Space Shuttle Decision, pp. 278-289, and Roger in 1985 when adjusted for inflation becomes $52.9 million in 1971 A. Pielke, Jr., "The Space Shuttle Program: ʻPerformance vs. Promise,ʼ" dollars or nearly seven times the 1971 estimate. "Pricing Options for the Center for Space and Geosciences Policy, University of Colorado, August Space Shuttle." 31, 1991; Logsdon, "The Space Shuttle Program: A Policy Failure?" pp. 17 See Diane Vaughan, The Challenger Launch Decision: Risky Technology, 1099-1105. Culture, and Deviance at NASA (Chicago: The University of Chicago U.S.C. App § §1 et seq. (1972). Harold W. Gehman to Sean OʼKeefe, February 25, 2003. 238 Report Volume I August 2003Show full note

¶The Performance Enhancements (PE) flight profile flown by STS-107 is a combination of flight software and trajectory design changes that were introduced in late 1997 for STS-85. These changes to the ascent flight profile allow the Shuttle to carry some 1,600 pounds of additional payload on International Space Station assembly missions. Although developed to meet the Space Station payload lift requirement, a modified

¶PE profile has been used for all Shuttle missions since it was introduced.

¶Triana and the requirements of the Commercial Space Act, and Appendix

¶C, "Accounting for Shuttle Costs." CAIB document CAB048-02680269.

¶One of the central purposes of this investigation, like those for other kinds of accidents, was to identify the chain of circumstances that caused the Columbia accident. In this case the task was particularly challenging, because the breakup of the Orbiter occurred at hypersonic velocities and extremely high altitudes, and the debris was scattered over a wide area. Moreover, the initiating event preceded the accident by more than two weeks. In pursuit of the sequence of the cause, investigators developed a broad array of information sources. Evidence was derived from film and video of the launch, radar images of Columbia on orbit, and amateur video of debris shedding during the in-flight breakup. Data was obtained from sensors onboard the Orbiter – some of this data was downlinked during the flight, and some came from an on-board recorder that was recovered during the debris search. Analysis of the debris was particularly valuable to the investigation. Clues were to be found not only in the condition of the pieces, but also in their location – both where they had been on the Orbiter and where they were found on the ground. The investigation also included extensive computer modeling, impact tests, wind tunnel studies, and other analytical techniques. Each of these avenues of inquiry is described in this chapter.

¶Because it became evident that the key event in the chain leading to the accident involved both the External Tank and one of the Orbiterʼs wings, the chapter includes a study of these two structures. The understanding of the accidentʼs physical cause that emerged from this investigation is summarized in the statement at the beginning of the chapter. Included in the chapter are the findings and recommendations of the Columbia Accident Investigation Board that are based on this examination of the physical evidence.