NASA personnel and leaders had a celebration planned on February 1, 2003, for the return of Columbia and its crew after the successful completion of STS-107. STS-107 had been launched from the Kennedy Space Center’s Launch Complex 39A on January 16 on a science mission that was dedicated to research in physical, life, and space sciences. It held the SPACEHAB Research Double Module and involved the execution of approximately 80 separate experiments, comprised of hundreds of samples and test points. The seven astronauts aboard had worked 24 hours a day, in two alternating shifts, to complete these experiments.
Unfortunately, STS-107 never made it home; both the vehicle and crew were lost during re-entry into the Earth’s atmosphere. NASA lost communication with Columbia a little before 9:00 a.m. E.S.T. on February 1, and when the shuttle failed to land at its appointed time of 9:16 a.m. at the Kennedy Space Center, NASA administrator Sean O’Keefe knew something was wrong. He said:
I immediately advised the President and the Secretary of Homeland Security, Tom Ridge, at the point after landing was due to have occurred at 9:16 a.m., and spoke to them very briefly to advise them that we had lost contact with the Shuttle orbiter, Columbia, and STS-107 crew. They offered, the President specifically offered, full and immediate support to determine the appropriate steps to be taken.
We then spent the next hour and a half working through the details and information of what we have received [concerning]…operational and technical issues.
We met with the family members of the astronauts who were here at the Kennedy Space Center and are soon to be departing back to the Johnson Space Center in Houston. The President has called and spoken to the family members to express our deepest national regrets. We have assured them that we will begin the process immediately to recover their loved ones and understand the cause of this tragedy.5
Columbia was the first orbiter built and flown in space, having undertaken 28 successful missions and with an anticipated service life of 100 flights. In February 2001, Columbia had received a major overhaul and update of its systems but it was still an aging vehicle. The STS-107 mission where it was lost was Columbia’s second flight following its overhaul, with the first one a successful servicing mission to the Hubble Space Telescope in March 2002.
The process of initiating a Columbia Accident Investigation Board (CAIB) began almost immediately. By 10:30 a.m. E.S.T. on Saturday, February 1, NASA convened “Space Shuttle Mishap Interagency Investigation Board. This seven-member board consisted of four top military aviation and safety officials, two civilians from the Federal Aviation Administration and Department of Transportation, and a NASA employee.
This board’s chair, U.S. Navy Admiral Harold W. Gehman Jr., had earlier co-chaired the commission that investigated the attack on the U.S.S. Cole in Aden, Yemen, on October 12, 2000, and once served as the commander-in-chief of U.S. Joint Forces Command. Because of congressional concerns about the independence of this accident investigation board, NASA on February 18, 2003, appointed new members, including former astronaut Sally Ride, and added flexibility in acquiring support staff and expertise outside from of NASA.
At the same time, with debris scattered over Texas, Louisiana, and other parts of the south-central United States, teams of investigators scoured the countryside for as much of Columbia as they could find. Within twenty-four hours of the accident, a large group was on the ground and working with local officials in Texas and Louisiana. The State of Texas activated 800 members of the Texas National Guard to assist with the retrieval of debris. By 4 February, more than 2,000 people from Federal Emergency Management Agency, Environmental Protection Agency, Federal Bureau of Investigation, Department of Defense, Department of Transportation, U.S. Forest Service, Texas National Guard, and state and local authorities were working to locate, document, and collect debris.
A high priority involved recovery of the remains of the seven member crew: Mission Commander Rick Husband; Pilot William “Willie” McCool; Mission Specialists Kalpana Chawla, David Brown, and Laurel Clark; Payload Commander Michael Anderson; and Payload Specialist Ilan Ramon. Two memorial services—one at the Johnson Space Center in Houston where President George W. Bush spoke and a second at Washington, D.C.’s, National Cathedral—served as a catharsis for a nation in mourning over the tragic loss. Spontaneous memorials also sprang up at NASA centers and the Smithsonian Institution’s National Air and Space Museum.
Among a lot of other Columbia debris, search teams found a 3-foot-wide steel ball that crushed part of the runway of the Nacogdoches, Louisiana, airport. Another part of Columbia tore through the roof of a local dentist’s office, which might have been filled with people if it were not Saturday morning. And a 3-by-4-foot metal slab crashed into a bank parking lot near a drive-up ATM. In all, about 80,000 pounds of Columbia debris rained down on mostly rural east Texas on February 1. Fortunately, nobody on the ground was killed or maimed.
NASA sent all of the debris discovered to a 40,000-square-foot hangar at the Kennedy Space Center, Florida, the same place that Challenger debris had been analyzed, where technicians marked three outlines of the shuttle Columbia‘s wings to lay down wreckage from the bottom, the middle, and the top. At the time that most search operations were concluded in early May 2003, the investigators had found more than 50,000 pieces, representing approximately 40 percent of Columbia, unfortunately, hardly anything from the left wing—identified early on as the location where the failure first occurred—was found. “I think the hardware is telling us something,” said Michael D. Leimbach, the engineer in charge of the reconstruction. He noted that a lot more heat entered the left side than the right side of the vehicle, burning away the aluminum structure before it reached Earth. Among other useful discoveries, the investigators recovered intact a data recorder box that stored critical information until seconds before the shuttle disintegrated.
From this investigation a viable theory concerning the probable cause of the accident emerged. On May 6, 2003, the CAIB released their working scenario for the accident. The Board commented that at approximately 81 seconds after a 10:39 a.m. EST launch on January 16, 2003, post launch photographic analysis determined that foam from the External Tank (ET) left bipod ramp area impacted Columbia in the vicinity of the lower left wing reinforced carbon-carbon (RCC) panels 5-9. While on orbit for 16 days, neither the Columbia crew nor controllers on the ground had any indication of damage based on orbiter telemetry, crew downlinked video, still photography, or crew reports.
Even so, post-flight evaluation by Air Force Space Command of radar tracking data indicated an object on flight day two, presumably a piece off the orbiter’s left lower wing, flying near Columbia before reentering the atmosphere two and a half days later. This was probably a piece of an RCC T-seal or RCC panel with a rib, both critical components of the wing. When the vehicle began reentry this damaged section of the wing, especially RCC panel 8/9, said CAIB members, “was subjected to extreme entry heating over a long period of time, leading to RCC rib erosion, severely slumped carrier panel tiles, and substantial metallic slag deposition on the RCC panels nearest the damaged area.” Between 8:49 and 8:56 a.m. EST virtually all sensors failed in the left wing, with most measurements failing within the first two minutes of the breach. The Board concluded:
A significant change in the vehicle aerodynamics was observed at 8:54:20 EST, indicating a change in the damage to the left wing. At the same time several very bright debris events were seen in ground-based videos. Soon after the hot gas entered the left wing multiple debris events were captured on video by observers on the ground. These video images begin at 8:53:46 EST (20 seconds after California coastal crossing) and end with Columbia’s final break-up. The exact source of the debris may never be fully understood. However, upper wing skin and Thermal Protection System (TPS) are possible candidates. Damage to the internal aluminum wing structure was most probable during this timeframe as well. These debris events appeared to affect orbiter communication. There were 13 unexplained communication dropouts in this timeframe.
By 8:56:16 EST hot gas had penetrated the wheel well wall as indicated by an off-nominal rise in hydraulic line temperatures. Another significant change in Columbia’s aerodynamics occurred at 8:58:09 EST, accompanied by several more debris events. The vehicle responded to this event with a sharp change in its aileron trim. Additionally, by 8:58:56 EST all left main gear tire pressure and temperature measurements were lost, indicating a rapid progression of damage inside the wheel well. A continual progression of left wing damage caused another abrupt change in the vehicle’s aerodynamics at 8:59:29 EST. Columbia attempted to compensate by firing all four right yaw jets. By 8:59:32 EST the Mission Control Center had lost all telemetry data. MADS recorder data was lost at 9:00:14 EST. Based on video imagery, main vehicle aerodynamic break-up occurred at 9:00:23 EST.