We've been enjoying this evening's programming on the History Channel: "Failure Is Not an Option", two two-hour documentaries on the U. S. manned spaceflight program, as told by the men and women in Mission Control. The first program covers the beginnings through the end of Project Apollo; the second covers Skylab, Apollo-Soyuz, and the Space Shuttle. They'll be repeated starting at 12 a.m. Eastern time -- just 45 minutes from now.

Today is the 20th anniversary of the loss of the Challenger. I was working afternoons at Draper Laboratory, the research lab just off the MIT campus where the Apollo Guidance Computer was developed. I remember walking in that day to find everyone in the department gathered in the conference room, watching the TV, stunned. A few of the people in the room were veterans of Project Apollo, still more had been involved in the development of the flight control and avionics systems on the Space Shuttle.

Sometimes, when you're working on some tiny piece of an engineering problem, you can lose sight of the fact that lives may depend on your getting your piece right. It's easy to get complacent; you have one success after another, it all seems routine, and then conditions come together to turn a latent defect into a fatal flaw. This anniversary, and yesterday's 39th anniversary of the Apollo 1 fire, should call all engineers who develop and maintain components of safety-critical systems to remember that failure is not an option, and that failure prevention begins on the ground, on the drawing board.