Salem Press

The Eighties in America
Challenger Disaster

The Event: Space shuttle explosion
Date: January 28, 1986
Place: Kennedy Space Center, Florida

NASA's space shuttle Challenger disintegrated about seventy-three seconds after launch, killing the seven astronauts aboard, including civilian S. Christa McAuliffe. The public's shock over the disaster grew when the commission investigating its cause determined that the process NASA used to assess launch safety was seriously flawed. NASA suspended its piloted spaceflight program for thirty-two months, while the space shuttle fleet was modified.

The January, 1986, launch of Challenger attracted considerably more public attention than most of the twenty-four previous U.S. space shuttle flights, because it was to be the first flight in the National Aeronautics and Space Administration (NASA) Teacher in Space Project. S. Christa McAuliffe, a thirty-seven-year-old secondary school teacher from Concord, New Hampshire, had been selected in July, 1985, from a group of more than eleven thousand applicants, to become the first teacher to fly in space. McAuliffe, who was interviewed on television by Larry King, Johnny Carson, David Letterman, Regis Philbin, and others, immediately became a celebrity, and NASA received considerable favorable publicity in the months leading up to the flight.

The mission was led by Commander Francis R. "Dick" Scobee and piloted by Michael J. Smith. The crew of seven astronauts also included three mission specialists—Judith A. Resnik, Ellison S. Onizuka, and Ronald E. McNair, whose primary responsibility was the operation of orbiter systems—and two payload specialists, Gregory B. Jarvis and McAuliffe—whose primary responsibility was to conduct experiments. The mission was scheduled to deploy a Tracking and Data-Relay Satellite, to launch and recover the SPARTAN-Halley comet research observatory, and to broadcast two live science lessons to school children around the country.

A Delay-Plagued Launch
Challenger's launch was originally scheduled for January 22, 1986, but it was postponed to January 23 and then to January 24, because Challenger needed parts from the shuttle Columbia, but Columbia's return to Earth had been delayed several times. The January 24 launch was cancelled because of bad weather at the emergency landing site in Senegal. The emergency site was changed to Casablanca, Morocco, but because there were no landing lights at that site, the time of the launch had to be moved earlier in the day, so it would still be light in Casablanca when the shuttle lifted off in Florida. Weather conditions in the United States caused the launch to be pushed back to January 27. The January 27 launch was postponed because of a problem with the exterior handle on the orbiter's hatch.

On the morning of January 28, the launch was delayed for two hours when a liquid hydrogen monitor failed. Unusually cold weather, with the ambient air temperature near freezing, had prompted concern from Morton Thiokol, the contractor that built the shuttle's solid-rocket booster engines. Engineers warned that if the O-rings that sealed joints in these engines reached a temperature below 53 degrees Fahrenheit, there was no guarantee that they would perform properly. NASA officials, aware that the many delays were resulting in bad publicity, decided that it was safe to proceed with the launch.

The Short Flight
Challenger finally lifted off at 11:38 a.m. eastern standard time (EST) on January 28. A later examination of launch film showed the first sign of a problem less than 0.7 seconds into the flight, when puffs of dark smoke were emitted from the right-hand solid-rocket booster. Investigators later determined that the smoke resulted from a leak in a joint between sections of the booster. During the stress of liftoff, metal parts bent away from each other, the primary O-ring was too cold to seal, and hot gases vaporized both the primary O-ring and a secondary O-ring that served as a backup.

Particles of aluminum oxide rocket fuel are believed to have temporarily sealed the gap. But, about fifty-eight seconds into the flight, Challenger encountered an intense wind shear, a sudden change in wind speed and direction. This was the most severe wind shear recorded up to that time in the shuttle program. The resulting force broke the temporary seal. Within a second, a plume of rocket exhaust penetrated the joint, striking the shuttle's external fuel tank. Sixty-five seconds into the flight, the exhaust burned through the wall of the external tank, releasing hydrogen. At this point, both the astronauts and the flight controllers still believed the mission was proceeding normally.

Seventy-three seconds into the flight, with the shuttle at at an altitude of forty-eight thousand feet, the external tank disintegrated and the right solid-rocket booster rotated, causing Challenger to veer from its intended path. The shuttle was immediately torn apart by air pressure far exceeding its design limit. Television monitors showed a cloud of smoke and vapor where the shuttle had been just moments before. The strongest parts, the crew cabin and the solid-rocket boosters, separated from the rest of the debris and continued arcing upward.

Twenty-five seconds after the breakup, the crew compartment reached a peak height of sixty-five thousand feet and began plunging back toward the Atlantic Ocean. Most likely, some or all of the crew survived the breakup, because four of the personal air packs, which could provide oxygen after the cabin system failed, were activated. Two minutes and forty-five seconds after the breakup, the crew cabin impacted the ocean, producing a deceleration of more than two hundred g's (that is, more than two hundred times Earth's gravitational force), well beyond the design limit and sufficient to kill the crew. A distinctively shaped cloud of smoke remained visible in the air off Florida's coast, and the image of that cloud appeared on television news coverage of the disaster—first live and then on tape—throughout the day and for much of the rest of the week.

Impact
Although NASA had lost three astronauts during a ground test in preparation for the first crewed Apollo flight, the Challenger disaster represented the first time any American had perished during a spaceflight. Widespread interest in NASA's Teacher in Space Project attracted more attention to this launch than most shuttle missions. Many school children, including those in McAuliffe's school in New Hampshire, watched the launch live on televisions in their schools. Television coverage of the launch and disaster made the Y-shaped smoke trail left in the disintegrating shuttle's wake one of the most widely seen and troubling images of the decade.

A special commission, appointed by President Ronald Reagan, attributed the accident to a design flaw in the seals on the solid-rocket booster engines. The commission found engineering reports, dated prior to the shuttle's first flight, that indicated weakness in this design, and the commission concluded NASA's decision-making process was seriously flawed.

Following the Challenger disaster, NASA grounded the remainder of the shuttle fleet while the risks were assessed more thoroughly, design flaws were identified, and modifications were developed and implemented. This delayed a number of important NASA missions, including the launching of the Hubble Space Telescope and the Galileo probe to Jupiter. It also represented a serious blow to NASA's reputation, coloring the public perception of piloted spaceflight and affecting the agency's ability to gain continued funding from Congress.

Further Reading
Jensen, Claus. No Downlink: A Dramatic Narrative About the "Challenger" Accident and Our Time. New York: Farrar, Strauss & Giroux, 1996. An account of the Challenger disaster and the investigation to determine its cause.

Lieurance, Suzanne. The Space Shuttle "Challenger" Disaster in American History. Berkeley Heights, N.J.: Enslow, 2001. Describes the effect of the disaster on American space efforts; suitable for younger readers.

Penley, Constance. NASA/Trek: Popular Science and Sex in America. New York: Verso, 1997. Includes detailed feminist critiques of the media representation of Christa McAuliffe and of NASA'S response to the Challenger disaster.

Vaughan, Diane. The "Challenger" Launch Decision: Risky Technology, Culture, and Deviance at NASA. Chicago: University of Chicago Press, 1996. A 575-page account of the steps leading to the decision to launch Challenger.

George J. Flynn

See Also
Halley's comet; Science and technology; Space exploration; Space shuttle program.