Allan James McDonald (July 9, 1937 – March 6, 2021) was an American engineer, aerospace consultant, author and the director of the Space Shuttle Solid Rocket Motor Project for Morton-Thiokol, a NASA subcontractor. In January 1986, he refused to sign off on a launch of the Space Shuttle "Challenger" which then broke apart 73 seconds into flight; all seven astronauts on board were killed. Deeply affected by the loss of the "Challenger" astronauts, McDonald endeavored to reveal the truth about the pressures to stay on launch schedule that led to the tragedy. He co-authored the 2009 book "Truth, Lies, and O-Rings: Inside the Space Shuttle Challenger Disaster".