Encounter 15 · 15 of 42 · 27–28 January 1986
The night before
On 27 January 1986, engineers at Morton Thiokol recommended that Challenger not fly. They were on a telephone. The launch was the next morning.
Wasatch, Utah / Cape Canaveral
What didn’t work
The no-launch recommendation did not survive the call.
What they knew
- O-rings had already shown erosion. The 1985 memo was in the file.
- The night would be cold. No one had data for that cold.
- The recommendation from engineering, at first, was not to fly.
What they could not know
- Whether the rings would seal at that temperature.
- Whether a no-launch recommendation would survive the call.
- What stopping would cost the contractor, that night.
The situation
O-rings on the solid-rocket boosters had already shown erosion on earlier flights. Roger Boisjoly’s 31 July 1985 memo to Robert Lund had said so. Forecast temperatures at the Cape for 28 January 1986 were far below that experience. On a late teleconference from Wasatch, Thiokol engineering recommended no-launch. NASA managers pressed. Thiokol management reversed the engineers.
The engineers recommended that Challenger not fly. They were on a telephone. They did not have the last word.
The night. Not the plume.
- 27 January 1986, about 8:45 p.m. ESTThiokol engineering, from Wasatch, on a telephone. Vice President Bob Lund recommended Challenger not fly if the O-rings would be colder than 53 °F, the coldest prior flight.
- The same eveningNASA managers pressed. There was no data for that cold. The recommendation from engineering, at first, was not to fly.
- About 10:30 p.m. ESTThiokol caucus, about thirty minutes. Roger Boisjoly and Arnold Thompson objected. Jerald Mason asked Lund to take off his engineering hat and put on his management hat. Management reversed the engineers.
- The signatureAllan McDonald refused to sign the launch recommendation. Someone else did.
- 28 January, morningThe no-launch recommendation had not survived the call. The vehicle was on the pad. This Guide records the night before, not the plume. Feynman’s ice-water demonstration is later theatre, useful and not this call.
What was at stake
Seven people on the vehicle. A schedule. A contractor’s relationship with a customer.
The next move
Management signed a launch recommendation. The engineers did not have the last word.
What they had
- Charts
- A telephone
- A prior memo
- No authority to stop the countdown
What happened
Challenger was lost. The Rogers Commission heard the night’s story. Boisjoly testified. He later left the company. This Guide records the night before, not the plume.
Who could stop the countdown, and who could not?
Private. No one else will see it.