It Is Rocket Science, Actually

Forty years after NASA took delivery of its first launch ready Shuttle, Nik Rawlinson looks back at the software and systems that made the world’s only viable space plane fly

- Nik Rawlinson

Onboard computers played a relatively minor role in the US moon landings. They handled guidance and navigation, which isn’t much more than in-car satnav manages today. Things were very different by the time of the Space Shuttle’s first flight in 1981, which NASA had envisaged as a pseudo-Uber in orbit.

Almost a decade earlier, with the Shuttle still on the drawing board, NASA administrator Thomas Paine had expounded its benefits. Quoted by the Birmingham Daily Post, he’d explained: “With the coming of the Space Shuttle, it would be possible for many men and women of many nationalities to fly as passengers. They will not need elaborate training, but simply to be in good health.”

NASA wanted several Shuttles in simultaneous orbit, but managing a fleet of that size would be far too complex for banks of computers stationed back on Earth. It would only work if the Shuttle became the world’s first flying computer. So, while commercial airlines were still mechanical devices, with moving cables physically connecting the pilot’s yoke to the rudder, the Shuttle pioneered fly-by-wire operation. Output from the cockpit fed a series of onboard interfaces. These prioritised each command and transmitted them to the engines, flaps and life support systems, entirely as bits and bytes. No wonder NASA considered software “the most critical component of the Shuttle”.

It’s 40 years since NASA took delivery of Columbia, the fleet’s first space-ready craft. This is the story of how its software came to be written, and the compromises that had to be made before the era of cheap computing we take for granted today.

The long tail