[welterde]

Don't know about Rosetta, but at ESA LEON [1] is quite popular.

But it is certainly custom hardware and a custom OS, because you need radiation-hardened chips (even for earth-satellites) and extreme reliability.

[1] http://en.wikipedia.org/wiki/LEON

[VexXtreme]

Interesting. You'd think that a custom radiation-hardened x86 or ARM variant would be sufficient.

Are there any space exploration vehicles running Linux?

[rsynnott]

ARM is pretty new as a remotely high-performance thing. x86 is used a bit; the Hubble space telescope has a radiation hardened 486, for instance (originally a 386). A good few spacecraft use radiation hardened PowerPCs, M68Ks, and other common designs. Even that ESA chip isn't anything hugely custom; it's a SPARC-V8 variant.

[XorNot]

Don't know about exploration, but SpaceX runs Linux for all it's rocket firmware and I imagine Dragon capsules will as well.

[ddeck]

There was as discussion with John Muratore (SpaceX director of vehicle certification) posted on HN a while back with some interesting notes on this:

https://news.ycombinator.com/item?id=6125834

[TkTech]

Absolutely! Hell, the ISS is all Linux now.

[InclinedPlane]

ISS laptops run linux, the ISS control software itself does not run on linux.