Linux in SpaceX

SpaceX: We've launched 32,000 Linux computers into space for Starlink internet | ZDNet

"Each of SpaceX's monthly launches of 60 internet-beaming Starlink satellites carries 4,000 stripped-back Linux computers, SpaceX software engineers have revealed.
...total count to around 480 and moving it closer to the 800 it needs to provide moderate coverage over the US.

SpaceX recently applied to the Federal Communications Commission to launch 30,000 second-generation satellites over and above the 12,000 that had already been approved. Assuming the second-generation satellites carry the same number of Linux computers, it would mean SpaceX plans to send at least two million Linux computers into space in the next few years."

From Earth to orbit with Linux and SpaceX | ZDNet

"The Falcon 9's onboard operating system is a stripped-down Linux running on three ordinary dual-core x86 processors. The flight software itself runs separately on each processor and is written in C/C++.

Ordinary? Yes, ordinary. You see, spacecraft CPUs are far from the newest and greatest. They're developed for spacecraft, which takes years -- even decades -- to go from the drafting board to launch. For example, the International Space Station (ISS) runs on 1988-vintage 20 MHz Intel 80386SX CPUs."

Usually, though, chips that go into space aren't ordinary chips. CPUs that stay in space must be radiation-hardened. Otherwise, they tend to fail due to the effects of ionizing radiation and cosmic rays. These customized processors undergo years of design work and then more years of testing before they are certified for spaceflight.