1.5 The Challenger Accident
― チャレンジャー事故 ―

The illusion that the Space Shuttle was an operational system, safe enough to carry legislators and a high-school teacher into orbit, was abruptly and tragically shattered on the morning of January 28, 1986, when Challenger was de-stroyed 73 seconds after launch during the 25th mission (see Figure 1.5-1). The seven-member crew perished.

Figure 1.5-1. the Space Shuttle Challenger was lost during ascent on January 28, 1986, when an O-ring and seal in the left Solid Rocket Booster failed.

To investigate, President Reagan appointed the 13-member Presidential Commission on the Space Shuttle Challenger Accident, which soon became known as the Rogers Commission, after its chairman, former Secretary of State William P. Rogers.*18 Early in its investigation, the Commission identified the mechanical cause of the accident to be the failure of the joint of one of the Solid Rocket Boosters. The Commission found that the design was not well understood by the engineers that operated it and that it had not been adequately tested.

When the Rogers Commission discovered that, on the eve of the launch, NASA and a contractor had vigorously debated the wisdom of operating the Shuttle in the cold temperatures predicted for the next day, and that more senior NASA managers were unaware of this debate, the Commission shifted the focus of its investigation to "NASA management practices, Center-Headquarters relationships, and the chain of command for launch commit decisions."*19 As the investigation continued, it revealed a NASA culture that had gradually begun to accept escalating risk, and a NASA safety program that was largely silent and ineffective.

The Rogers Commission report, issued on June 6, 1986, recommended a redesign and recertification of the Solid Rocket Motor joint and seal and urged that an independent body oversee its qualification and testing. The report concluded that the drive to declare the Shuttle operational had put enormous pressures on the system and stretched its resources to the limit. Faulting NASA safety practices, the Commission also called for the creation of an independent NASA Office of Safety, Reliability, and Quality Assurance, reporting directly to the NASA Administrator, as well as structural changes in program management.*20 (The Rogers Commission findings and recommendations are discussed in more detail in Chapter 5.) It would take NASA 32 months before the next Space Shuttle mission was launched. Dur-ing this time, NASA initiated a series of longer-term vehicle upgrades, began the construction of the Orbiter Endeavour to replace Challenger, made significant organizational changes, and revised the Shuttle manifest to reflect a more realistic flight rate.

The Challenger accident also prompted policy changes. On August 15, 1986, President Reagan announced that the Shut-tle would no longer launch commercial satellites. As a result of the accident, the Department of Defense made a decision to launch all future military payloads on expendable launch vehicles, except the few remaining satellites that required the Shuttles unique capabilities.

In the seventeen years between the Challenger and Columbia accidents, the Space Shuttle Program achieved significant successes and also underwent organizational and managerial changes. The program had successfully launched several important research satellites and was providing most of the "heavy lifting" of components necessary to build the International Space Station (see Figure 1.5-2). But as the Board subsequently learned, things were not necessarily as they appeared. (The post-Challenger history of the Space Shuttle Program is the topic of Chapter 5.)

Figure 1.5-2. The International Space Station as seen from an approaching Space Shuttle.