International Space Station switches to Linux.

[Ruedii]

The International Space Station recently announced they would convert the remaining Windows computers they used over to Debian Linux. They cited security, stability and an OS that "would give us in-house control. So if we needed to patch, adjust or adapt, we could."

[Nuke]

really makes sense considering nasa already has a large amount of linux knowhow on hand. linux is really awesome if you know what youre doing.

[hugix]

To be fair, this is only for the client computers (the laptops you see in the videos made onboard). The ISS itself (and all of her subsystems) probably use a system written by NASa / ESA / RC / JAXA programmers.

[K^2]

I wouldn't be surprised if the main systems run a custom kernel that's based on Linux. There is no good reason to write a kernel completely from scratch for such a task.

[DerekL1963]

I wouldn't be surprised if the main systems run a custom kernel that's based on Linux. There is no good reason to write a kernel completely from scratch for such a task.

Yes, there's a very good reason - Linux essentially didn't exist when the main control systems were being designed and developed. (Some of this stuff runs back into the late 80's.) By the time Linux was anything even remotely approaching mature enough to be considered for such a purpose, the station's design was long since frozen.

[tavert]

The main guidance computers are in Zvezda, evidently they're ESA-designed: http://www.esa.int/For_Media/Press_Releases/International_Space_Station_docks_successfully_with_Zvezda_module

GNC computers, at least in these established programs with so much legacy technology to utilize, aren't running something we would recognize as an OS, it's very specialized real-time stuff.

Many of the Russian spacecraft use ancient analog computers, or simple digital I/O layers on top of the analog processor. They didn't replace these on Soyuz until 2 or 3 years ago: http://www.computer-museum.ru/english/argon16.htm

Edit: My bad, the Argon flight computer itself is digital, but interfaced many separate analog subsystems until the TMA-M revision: http://spectrum.ieee.org/aerospace/space-flight/a-digital-soyuz

Edited May 10, 2013 by tavert

[K^2]

Yes, there's a very good reason - Linux essentially didn't exist when the main control systems were being designed and developed.

Ah, well, yes. That would be a good reason.

[DerekL1963]

GNC computers, at least in these established programs with so much legacy technology to utilize, aren't running something we would recognize as an OS, it's very specialized real-time stuff.

Even (space) programs using current hardware (most of which is old enough to be considered legacy by consumer standards*) tend to avoid Linux (or any other commercial OS) for pretty much that reason... It's just not suited for the task. Hard real time and deterministic behavior is... very hard (read; expensive) to accomplish and pointless for PC's, so consumer grade OSes don't even try.

I think a lot of people don't realize there's a whole heck of a lot more to the computer world than consumer hard- and soft- ware.

*Mostly because consumer grade gear is on permanent 100 000× time warp because it's driven by the bottom line over pretty much anything else. Space programs want proven reliability and 110% certainty. An obscure processor or OS bug or one-in-a-billion convergence that causes a fault that causes KSP to crash is no biggie for you and me, but when a half a billion dollars or lives are on the line, that's generally unacceptable.

[tavert]

Even (space) programs using current hardware (most of which is old enough to be considered legacy by consumer standards*) tend to avoid Linux (or any other commercial OS) for pretty much that reason... It's just not suited for the task. Hard real time and deterministic behavior is... very hard (read; expensive) to accomplish and pointless for PC's, so consumer grade OSes don't even try.

I believe SpaceX is an exception, it sounds as though they do actually use Linux on their flight computers, but in a multiple-redundancy voting system: http://www.aviationweek.com/Blogs.aspx?plckBlogId=Blog%3a04ce340e-4b63-4d23-9695-d49ab661f385&plckPostId=Blog%3a04ce340e-4b63-4d23-9695-d49ab661f385Post%3aa8b87703-93f9-4cdf-885f-9429605e14df

Dunno if calling Linux a "commercial" OS is quite fair, it does have lots of uses in embedded systems and such, but it's also a lot more general-purpose than it needs to be for those tasks, and can't do all of them due to the issues you mentioned.

[Nuke]

the reason spacecraft tend to use outdated computer hardware (and electronics in general) is because it takes about 10 years to rad hard a part. thats why the space shuttle still used core memory for its computers, and why the hubble was upgraded with a 486 well past that chips prime.