6 ms·

What is the Mars Curiosity Rover's software built in?

99 points by joshuahedlund 14y ago

kylemaxwell 14y ago
You could do worse than start at the NASA Github page: https://github.com/nasa/ https://github.com/nasa/
Sukotto 14y ago
Tangentially, "They Write the Right Stuff" was a very interesting 1996 article about writing the software running the space shuttle. http://web.archive.org/web/20050830190246/www.fastcompany.com/magazine/06/writestuff.html http://web.archive.org/web/20050830190246/www.fastcompany.co...
sodelate 14y ago
to be sure , vxworks
natep 14y ago
Thanks for posting! The existing answer had almost no detail, so I wrote another: http://programmers.stackexchange.com/a/159687/61021 http://programmers.stackexchange.com/a/159687/61021
- mturmon 14y ago
  You dug up a great talk, but I could not find the PDF. There's no link, and the expected file FSW10_Cichy.pdf is not present with all the other PDFs in the download directory. The author, Ben Cichy, was the guy in Flight Control during the landing last night, sitting behind the position marked "Flight Software". So he's definitely a good source for the background ;-)
  - natep 14y ago
    I don't know if there is a PDF. The media player is interesting, though, in that it's actually just some javascript that loads a sequence of stills at the appropriate time, and if you look at the source, you can write, say, a python script to download all the images, which I did. When I get home, I'll see if I can find it.
  - natep 14y ago
    OK, here's the script I had hacked together. It (or some previous version), successfully downloaded all of the images, and a timings.txt. It was then supposed to create a movie file of each slide of the appropriate length, concatenate them all, and add the audio. But my VM kept crashing, and then I never had time to get back to it. Plus, the movie file ended up being very large. But if you have python 2.7.2+, you can run it and grab the images. https://github.com/nsp/gazpacho https://github.com/nsp/gazpacho
ColinDabritz 14y ago
I believe the confusion between '500,000 lines' in the question vs '2.5 million/3.5 million' in the answers is the context. The 500,000 number is involved in the entry, descent, and landing (EDL) process specifically, and the rover systems are millions overall. Not sure why the values are 1m different, but the 2.5m citation is what is in the linked PDF.
- sanxiyn 14y ago
  Guess on 1 million difference: 2.5m citation is dated 2009, 3.5m citation is dated 2010.
  - natep 14y ago
    It's hard for me to imagine 1M lines of code being written/generated in a year and then flown. I suspect either the first person was responsible for testing only 2.5M lines of it, or they used different counting methods. As the one who posted the larger figure, I'd say it's more reliable because it comes from the man who sat at the Flight Control station in the control center :D
- bfe 14y ago
  I'd think this is right, because the answer that gives the 2.5 million loc number also says that this code is descended from the code for Spirit/Oppie and further from Soujourner, but the EDL system for Curiosity is so different from the ones for the older rovers, it has to involve a lot of entirely new code.
eliben 14y ago
So much programming language research in the past 40 years, but C is, no doubt, still king.
- jetti 14y ago
  It is a lot of money to possibly waste on a language that is not proven, so why not stick with what works?
stox 14y ago
The processor is an embedded, radiation hardened, version of the PowerPC.
amirmansour 14y ago
The two previous Mars rovers had some Java on them. I saw the code with my own eyes!
- sgt 14y ago
  I bet James Gosling was proud.
  - amirmansour 14y ago
    I bet he was. I also bet that MSL also has some Java on it since JPL is all about code reuse.
antirez 14y ago
Not sure what means that most of the C code is auto generated. From what?
- mgurlitz 14y ago
  They make models of the software before writing any code, and a lot of the code can be generated from the models. There's a guarantee that if the model is correct so is the code. Or, you don't have to check that your hand-written C actually matches the system you were building.
  - RodgerTheGreat 14y ago
    This is really key. The guarantees provided by modeling systems are of limited value if the translation between model and runnable code involves manual labor.
  - msh 14y ago
    What do you mean by model?
    - andor 14y ago
      A formal model of how the software is supposed to behave. Models can be proven to have certain properties (e.g. deadlock-free, cruise control always turns off when brake is hit), while with software you're usually limited to testing. A proof guarantees that the software works for all possible inputs, whereas when testing only some inputs are tried. To model individual processes, one could use automata, for interaction of processes there are process calculi. http://en.wikipedia.org/wiki/Formal_methods http://en.wikipedia.org/wiki/Formal_methods
    - gtani 14y ago
      Compilers that are verified/validated (in some sense): http://compcert.inria.fr/compcert-C.html http://compcert.inria.fr/compcert-C.html http://www.cs.utah.edu/~regehr/papers/ http://www.cs.utah.edu/~regehr/papers/ http://lambda-the-ultimate.org/node/4571 http://lambda-the-ultimate.org/node/4571 ------------- The "Related Work" section in this UVa dissert probably most closely answere your question http://www.cs.virginia.edu/~jck/publications/Xiang.Yin.dissertation.pdf http://www.cs.virginia.edu/~jck/publications/Xiang.Yin.disse...
gm34 14y ago
Are you planning hacking the Rover ? :)
zwieback 14y ago
The JPL coding standards (http://lars-lab.jpl.nasa.gov/JPL_Coding_Standard_C.pdf http://lars-lab.jpl.nasa.gov/JPL_Coding_Standard_C.pdf) linked in one of the comments seems surprisingly flexible. I would have expected more limitations.
msantos 14y ago
Let's hope Nasa is not cutting corners like Boeing did (does?) running VxWorks on 747s and using telnet to connect to any 747 aircraft while in flight. EDIT: Boeing only connected to aircrafts to retrieve flight stats and other data. Or when following a customer request. The point I wanna raise is not the fact Boeing connects to aircrafts, but the fact they do so using non-crypt ol'telnet

99 points by joshuahedlund 14y ago

You could do worse than start at the NASA Github page: https://github.com/nasa/ https://github.com/nasa/

Tangentially, "They Write the Right Stuff" was a very interesting 1996 article about writing the software running the space shuttle. http://web.archive.org/web/20050830190246/www.fastcompany.com/magazine/06/writestuff.html http://web.archive.org/web/20050830190246/www.fastcompany.co...

sodelate 14y ago

to be sure , vxworks

natep 14y ago

Thanks for posting! The existing answer had almost no detail, so I wrote another: http://programmers.stackexchange.com/a/159687/61021 http://programmers.stackexchange.com/a/159687/61021

mturmon 14y ago
You dug up a great talk, but I could not find the PDF. There's no link, and the expected file FSW10_Cichy.pdf is not present with all the other PDFs in the download directory. The author, Ben Cichy, was the guy in Flight Control during the landing last night, sitting behind the position marked "Flight Software". So he's definitely a good source for the background ;-)
- natep 14y ago
  I don't know if there is a PDF. The media player is interesting, though, in that it's actually just some javascript that loads a sequence of stills at the appropriate time, and if you look at the source, you can write, say, a python script to download all the images, which I did. When I get home, I'll see if I can find it.
- natep 14y ago
  OK, here's the script I had hacked together. It (or some previous version), successfully downloaded all of the images, and a timings.txt. It was then supposed to create a movie file of each slide of the appropriate length, concatenate them all, and add the audio. But my VM kept crashing, and then I never had time to get back to it. Plus, the movie file ended up being very large. But if you have python 2.7.2+, you can run it and grab the images. https://github.com/nsp/gazpacho https://github.com/nsp/gazpacho

ColinDabritz 14y ago

I believe the confusion between '500,000 lines' in the question vs '2.5 million/3.5 million' in the answers is the context. The 500,000 number is involved in the entry, descent, and landing (EDL) process specifically, and the rover systems are millions overall. Not sure why the values are 1m different, but the 2.5m citation is what is in the linked PDF.

sanxiyn 14y ago
Guess on 1 million difference: 2.5m citation is dated 2009, 3.5m citation is dated 2010.
- natep 14y ago
  It's hard for me to imagine 1M lines of code being written/generated in a year and then flown. I suspect either the first person was responsible for testing only 2.5M lines of it, or they used different counting methods. As the one who posted the larger figure, I'd say it's more reliable because it comes from the man who sat at the Flight Control station in the control center :D
bfe 14y ago
I'd think this is right, because the answer that gives the 2.5 million loc number also says that this code is descended from the code for Spirit/Oppie and further from Soujourner, but the EDL system for Curiosity is so different from the ones for the older rovers, it has to involve a lot of entirely new code.

eliben 14y ago

So much programming language research in the past 40 years, but C is, no doubt, still king.

jetti 14y ago
It is a lot of money to possibly waste on a language that is not proven, so why not stick with what works?

stox 14y ago

The processor is an embedded, radiation hardened, version of the PowerPC.

amirmansour 14y ago

The two previous Mars rovers had some Java on them. I saw the code with my own eyes!

sgt 14y ago
I bet James Gosling was proud.
- amirmansour 14y ago
  I bet he was. I also bet that MSL also has some Java on it since JPL is all about code reuse.

antirez 14y ago

Not sure what means that most of the C code is auto generated. From what?

mgurlitz 14y ago
They make models of the software before writing any code, and a lot of the code can be generated from the models. There's a guarantee that if the model is correct so is the code. Or, you don't have to check that your hand-written C actually matches the system you were building.
- RodgerTheGreat 14y ago
  This is really key. The guarantees provided by modeling systems are of limited value if the translation between model and runnable code involves manual labor.
- msh 14y ago
  What do you mean by model?
  - andor 14y ago
    A formal model of how the software is supposed to behave. Models can be proven to have certain properties (e.g. deadlock-free, cruise control always turns off when brake is hit), while with software you're usually limited to testing. A proof guarantees that the software works for all possible inputs, whereas when testing only some inputs are tried. To model individual processes, one could use automata, for interaction of processes there are process calculi. http://en.wikipedia.org/wiki/Formal_methods http://en.wikipedia.org/wiki/Formal_methods
  - gtani 14y ago
    Compilers that are verified/validated (in some sense): http://compcert.inria.fr/compcert-C.html http://compcert.inria.fr/compcert-C.html http://www.cs.utah.edu/~regehr/papers/ http://www.cs.utah.edu/~regehr/papers/ http://lambda-the-ultimate.org/node/4571 http://lambda-the-ultimate.org/node/4571 ------------- The "Related Work" section in this UVa dissert probably most closely answere your question http://www.cs.virginia.edu/~jck/publications/Xiang.Yin.dissertation.pdf http://www.cs.virginia.edu/~jck/publications/Xiang.Yin.disse...

gm34 14y ago

Are you planning hacking the Rover ? :)

zwieback 14y ago

The JPL coding standards (http://lars-lab.jpl.nasa.gov/JPL_Coding_Standard_C.pdf http://lars-lab.jpl.nasa.gov/JPL_Coding_Standard_C.pdf) linked in one of the comments seems surprisingly flexible. I would have expected more limitations.

msantos 14y ago

Let's hope Nasa is not cutting corners like Boeing did (does?) running VxWorks on 747s and using telnet to connect to any 747 aircraft while in flight. EDIT: Boeing only connected to aircrafts to retrieve flight stats and other data. Or when following a customer request. The point I wanna raise is not the fact Boeing connects to aircrafts, but the fact they do so using non-crypt ol'telnet