Columbia Accident Investigation Board (CAIB) Synopsis
By: Jennifer Troxell, NASA History Office
The Columbia Accident Investigation Board was created to determine the cause of the Columbia accident and to recommend ways to improve the safety of Shuttle flight. The Chair of the Board was retired Navy Admiral Harold W. Gehman Jr. The members of the board were: Rear Admiral Stephen Turcotte, Commander, Naval Safety Center; Maj. General John Barry, Director, Plans and Programs, Headquarters Air Force Materiel Command; Maj. General Kenneth W. Hess, Commander, Air Force Safety Center; Dr. James N. Hallock, Chief, Aviation Safety Division, Department of Transportation Volpe Center; Mr. Steven B. Wallace, Director of Accident Investigation, Federal Aviation Administration; Brig. General Duane Deal, Commander, 21st Space Wing, USAF; Mr. Scott Hubbard, Director, NASA Ames Research Center; Mr. Roger E. Tetrault, Retired Chairman, McDermott International, Inc; Dr. Sheila Widnall, Professor of Aeronautics and Astronautics and Engineering Systems, MIT; Dr. Douglas D. Osheroff, Professor of Physics and Applied Physics, Stanford University; Dr. Sally Ride, Professor of Space Science, University of California at San Diego; and Dr. John Logsdon, Director of the Space Policy Institute, George Washington University.
The Board published its report on August 26, 2003. In advance of the final report, several preliminary recommendations as well as a working scenario were published.
In advance of the final report, CAIB made several recommendations to NASA, to assist engineers in updating flight related safety features for the shuttle prior to return to flight. The reference numbers in parentheses, after the recommendation indicate the recommendation numbers listed in the final report.
The first recommendation was that NASA develop an inspection plan to examine the Reinforced Carbon Carbon (RCC) system components (R3.3-1). The RCC system is used on the parts of the orbiter that are subjected to the greatest amount of heat during reentry. These areas include the leading edges of the wings, the area aft of the nose cap, and the area around the forward orbiter/external tank attachment structure. The Board found that the current techniques that are used to examine the RCC system are incapable of thoroughly assessing the RCC’s structural integrity, its supporting structure, and the attached hardware. The CAIB believed that NASA “should take advantage of advanced non-destructive inspection technology” to mitigate future risk to the space shuttles and crew.[i]
The second recommendation stated that NASA should amend its existing Memorandum of Agreement with the National Imagery and Mapping Agency (NIMA) “to make on-orbit imaging for each Shuttle flight a standard requirement (R6.3-2)[ii]. The CAIB determined that not every imaging resource the United States government had was utilized in order to assess the damage of the Columbia while still in orbit.
Recommendation three examined repair capability (R6.4-1). The CAIB acknowledged that both during flight and in the investigation following the incident the lack of repair capability was cited as potentially being a factor in decisions that were made during the damage assessment process.[iii] The CAIB also suggested that for all future missions to the International Space Station (ISS), NASA develop a method to inspect and conduct emergency repairs to the Thermal Protection System (TPS) tiles and RCC while docked at the ISS and recommended that a “comprehensive autonomous […] inspection and repair capability” be developed for Shuttle missions that do not dock at the ISS.[iv] The CAIB further recommended that TPS inspections be conducted and should be finished early on every mission. The end goal is to develop a “fully autonomous capability for all missions”, in the event “that an ISS mission does not achieve the necessary orbit, fails to dock successfully, or suffers damage during or after docking.”[v]
Both recommendation four and five address the Shuttle imaging system (R3.4-1, R3.4-2, R3.4-3). The Board found that the “lack of high resolution, high speed cameras” compromised the ability of the debris team to assess the impact of the foam debris on Columbia.[vi] Currently cameras at Kennedy Space Center and the Eastern Range are incapable of providing the best possible ascent engineering data, according to the CAIB.[vii] The CAIB recommended upgrading the imaging system to provide at minimum “three useful views of the Space Shuttle from liftoff to at least Solid Rocket Booster separation,” and further recommended exploring the use of ships or aircraft to take additional pictures and observations of the shuttle during launch.[viii] Recommendation five specifically examines the External Tank (ET) (R3.4-2) and the Thermal Protection System (TPS) (R3.4-3) imaging systems. The CAIB found that on-board imaging capability is vital to assure that the best on-board images are obtained to provide engineers a better picture of the shuttle’s integrity.[ix] The CAIB recommended modifying one of the two on-board umbilical cameras in order to “downlink high-resolution images of the External Tank (ET) after separation,” and further recommended that a similar system be put into place to “downlink high-resolution images of the underside of the orbiter’s leading edge system and the forward section of the TPS.[x]
The CAIB also investigated communications procedures between NASA engineers and managers. The nature of Shuttle program is complex, given the high level of technology used and the multiple civilians, contractors, and Centers involved, each integral to the success of the program. CAIB found the need to communicate effectively between the individuals and organizations involved in the Shuttle program to be paramount, given the technology, and risk involved.[xi]
Pressure to stay on an existing launch schedule and inefficient resources to do so are considered to be contributing factors of the STS-107 accident.[xii] CAIB also found that NASA’s safety program falls short of achieving the level of safety necessary for the shuttle program.[xiii] As a result, CAIB recommended that the safety system at NASA be restructured to include an “independent Technical Engineering Authority that is responsible for technical requirements and waivers to them and will build a disciplined, systematic approach to identifying, analyzing, and controlling hazards throughout the life cycle of the Shuttle System.”[xiv] CAIB emphasized that the independent authority “should have no connection to or responsibility for schedule or program cost.”[xv] A full list of the CAIB’s findings and recommendations related to NASA’s organizational culture are listed in the final report.
The CAIB/NASA Accident Investigation Team Working Scenario was published July 8, 2003 and posted at on the CAIB website.[xvi]
Prior to SRB separation, Columbia’s left wing leading edge suffered a debris impact from the structure that connects the orbiter and the external tank (ET-Y bipod foam ramp), between Reinforced Carbon Carbon (RCC) panels.[xvii]
According to the data gathered an unknown object moved away from the Shuttle on flight day 2.[xviii] Materials tests were conducted to determine the identity of the object. It was found that of the objects tested, the object could only be a partial “WLE Tee seal, a whole WLE Tee seal, or a partial WLE RCC panel.”[xix]
The damage in the left wing RCC provided a pathway for hot gas to enter the left wing leading edge and support structure during entry. This resulted in significant damage to the left wing and the subsequent loss of vehicle control, leading to aerodynamic breakup.[xx]
In addition to the five preliminary recommendations published by the CAIB, there were an additional 23 recommendations in the final report. Preliminary recommendation 5 was split into two separate requirements, one for the external tank images and the other for the orbiter wing images, for a total of 29 recommendations.
The spreadsheet section is primarily organized according to the sections discussed in the CAIB report. The findings have been placed with the recommendations that correspond to them. Some of the findings have been cited more than once. A synopsis to summarize the recommendation(s) and its corresponding findings has also been added. The colors serve only to distinguish between recommendation sections.
The complete report, as well as its additional appendices is available for download on www.caib.us until February 1, 2004. It is also available at http://www.nasa.gov/columbia/home/index.html on the Web. A hardcopy of the CAIB report may be ordered from the Government Printing Office by visiting www.gpo.gov on the Web.
By: Jennifer Troxell
NASA History Office
[xi] Columbia Accident Investigation Board Report. Government Printing Office, 2003: 187-189.
[xii] ibid, 139.
[xiii] ibid, 192.
[xiv] ibid. 193.
[xvi] Columbia Accident Investigation Board/ NASA Accident Investigation Team Working Scenario, 7-8-03, <http://www.caib.us/news/working_scenario/default.html> access date: 7-16-03.