page_title: Space Shuttle Challenger disaster
section_title: Rogers Commission
hierarchical_section_title: Space Shuttle Challenger disaster / Investigation / Rogers Commission
context_page_description: The Space Shuttle Challenger disaster was a fatal incident in the United States space program that occurred on January 28, 1986, when the Space Shuttle Challenger broke apart 73 seconds into its flight, killing all seven crew members aboard. The crew consisted of five NASA astronauts, and two payload specialists. The mission carried the designation STS-51-L and was the tenth flight for the Challenger orbiter.
  The spacecraft disintegrated over the Atlantic Ocean, off the coast of Cape Canaveral, Florida, at 11:39 a.m. EST. The disintegration of the vehicle began after a joint in its right solid rocket booster failed at liftoff. The failure was caused by the failure of O-ring seals used in the joint that were not designed to handle the unusually cold conditions that existed at this launch. The seals' failure caused a breach in the SRB joint, allowing pressurized burning gas from within the solid rocket motor to reach the outside and impinge upon the adjacent SRB aft field joint attachment hardware and external fuel tank. This led to the separation of the right-hand SRB's aft field joint attachment and the structural failure of the external tank.
context_section_description: The Presidential Commission on the Space Shuttle Challenger Accident, also known as the Rogers Commission after its chairman, was formed to investigate the disaster. The commission members were Chairman William P. Rogers, Vice Chairman Neil Armstrong, David Acheson, Eugene Covert, Richard Feynman, Robert Hotz, Donald Kutyna, Sally Ride, Robert Rummel, Joseph Sutter, Arthur Walker, Albert Wheelon, and Chuck Yeager. The commission worked for several months and published a report of its findings. It found that the Challenger accident was caused by a failure in the O-rings sealing a joint on the right solid rocket booster, which allowed pressurized hot gases and eventually flame to "blow by" the O-ring and make contact with the adjacent external tank, causing structural failure. The failure of the O-rings was attributed to a faulty design, whose performance could be too easily compromised by factors including the low ambient temperature on the day of launch. The O-rings would not work properly at ambient temperatures below 50 °F (10 °C)- and it was 36 °F (2 °C) on the morning of the launch. According to the report in July 1985, a memorandum was sent to Michael Weeks, the agency's No. 2 shuttle official, and Jesse W. Moore, the associate administrator in charge of the shuttle program, raising attention to the "failure history" of the O rings and recommending a review of the matter.
  More broadly, the report also considered the contributing causes of the accident. Most salient was the failure of both NASA and Morton-Thiokol to respond adequately to the danger posed by the deficient joint design. Rather than redesigning the joint, they came to define the problem as an acceptable flight risk. The report found that managers at Marshall had known about the flawed design since 1977, but never discussed the problem outside their reporting channels with Thiokol—a flagrant violation of NASA regulations. Even when it became more apparent how serious the flaw was, no one at Marshall considered grounding the shuttles until a fix could be implemented. On the contrary, Marshall managers went as far as to issue and waive six launch constraints related to the O-rings. The report also strongly criticized the decision-making process that led to the launch of Challenger, saying that it was seriously flawed:
  failures in communication ... resulted in a decision to launch 51-L based on incomplete and sometimes misleading information, a conflict between engineering data and management judgments, and a NASA management structure that permitted internal flight safety problems to bypass key Shuttle managers.
caption: Simplified cross section of the joints between rocket segments SRB; outside to left.
  Legend:
   A – steel wall 0.5 inches (12.7 mm) thick
   B – base O-ring gasket,
   C – backup O-ring gasket,
   D – Strengthening-Cover band,
   E – insulation,
   F – insulation,
   G – carpeting,
   H – sealing paste,
   I – fixed propellant