Two days later, NASA organized a press conference at the Cape with Hartsfield, who delivered a textbook performance of astronaut sangfroid. Discovery’s engines had shut down due to a faulty valve, and the fire had been caused by hydrogen propellant escaping from the rocket nozzles; as the gas burned with a transparent flame, it had been invisible to the crew—but could nonetheless have killed them if Resnik had opened the orbiter’s hatch.
