Making Spacecraft Autonomous

I've been seeing some interesting posts coming across my Twitter feed recently about the early Mercury and Gemini spacecraft. The contrast between them and the current SpaceX Crew Dragon and Boeing Starliner is quite remarkable, and most of that is due to the high degree of automation in modern spacecraft. 

While modern spacecraft are highly automated, there are trade-offs between automation and manual control. 

Ultimately, “the worst thing you can do is make something fully manual or fully autonomous,” says Nathan Uitenbroek, another NASA engineer working on Orion’s software development. Humans have to be able to intervene if the software is glitching up or if the computer’s memory is destroyed by an unanticipated event (like a blast of cosmic rays). But they also rely on the software to inform them when other problems arise. 

NASA is used to figuring out this balance, and it has redundancy built into its crewed vehicles. The space shuttle operated on multiple computers using the same software, and if one had a problem, the others could take over. A separate computer ran on entirely different software, so it could take over the entire spacecraft if a systemic glitch was affecting the others. Raines and Uitenbroek say the same redundancy is used on Orion, which also includes a layer of automatic function that bypasses the software entirely for critical functions like parachute release.