McDonald began working for
Morton-Thiokol, Inc in 1959 and was first part of the
Minuteman missile program; he assisted in designing its external insulation, and was the group leader at
Cape Canaveral during its flight tests. Thiokol was contracted by
NASA, and McDonald was placed in charge of the space shuttle's
solid rocket booster program for two years, with the job often requiring him to travel to the
Kennedy Space Center to assess a shuttle's condition prior to flight. In the lead-up to the
Challenger disaster, McDonald and fellow engineers from Thiokol, including
Bob Ebeling, Arnold Thompson and
Roger Boisjoly, were concerned that frigid overnight temperatures would affect the
O-ring seals in the solid rocket booster joints. McDonald refused to sign the official authorization form for a launch, saying, "If anything happens to this launch, I wouldn't want to be the person that has to stand in front of a board of inquiry to explain why we launched." During the launch of the
Challenger McDonald was at
Cape Canaveral as the senior representative for his company. The shuttle disintegrated during launch because of failure of the booster rocket joints, killing all seven astronauts. According to McDonald, NASA engineers pressured Thiokol into agreeing to the launch over the concerns expressed by Thiokol engineers, and later tried to cover that up. Testifying before the Presidential Commission on the Space Shuttle Challenger Accident, also known as the
Rogers Commission, McDonald's account revealed the coverup. Neufeld said McDonald "was treated as a traitor and pariah by NASA and his own company, but, thanks in part to congressional pressure, was allowed to redesign the boosters ..." unless McDonald's demotion was reversed. McDonald was promoted to vice president of engineering, charged with redesigning the solid rocket motors. When the
Space Shuttle program was restarted in 1988, the new booster rockets designed by McDonald were used until the end of the program in 2011. Antagonism to his testimony within Thiokol hindered his career and he was assigned to less prominent work throughout the 1990s. After he retired from the company in 2001, he became a public speaker on ethics and decision making. With
James R. Hansen, he co-authored the 2009 book
Truth, Lies, and O-Rings: Inside the Space Shuttle Challenger Disaster. McDonald donated his personal papers on the accident to
Chapman University in 2016 and expressed hope that they would assist in preventing the same mistakes from being made. == Membership==