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Comment by Aaargh20318 | Hacker News Reader

Aaargh20318·

Here's an article about it I read a while back, interesting read: https://www.fastcompany.com/28121/they-write-right-stuff

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This redundant software and hardware setup typically isn't necessary when humans aren't involved. The space shuttle system is similar to what you will find on a Boeing or Airbus aircraft. Redundant software, written by different people in different countries with completely different cultures in different languages (on purpose), running on multiple machines with different hardware and voting on the decisions to be made.

It is complete overkill when "all" you're going to lose is a robot and some pride, as with a space probe you want to have lots of features and this level of safety is very restrictive on development effort.

More than likely, the spacecraft in question is written in C or C++ with the help of RTEMS or VxWorks. It is probably running a radiation hardened, very slow processor.

They don't do 3x calculations and voting but they do often have redundant computers they can switch over to in case of failure. Curiosity had to switch to it's 'B-side' computer back in 2013 when A-side had a memory issue. Even when not carrying humans it's still a billion/million dollar mission that probably wouldn't be replicated for a while if ever (within the researchers life times at least) that could be scuttled by a softwer bug.

If anyone is interested JPL publishes their code standards doc for C: https://lars-lab.jpl.nasa.gov/JPL_Coding_Standard_C.pdf

Most spacecraft have some form of redundancy to guard against single point failures. It's a waste of money to send up failure prone hardware. Amateurs building cubesats, probably not, but the big players aren't going to take that sort of risk.

You are right, they have redudnancy in all cases - but it isn't usually software written by multiple teams with different hardware.

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