Comment by firebacon | Hacker News Reader

Comment by firebacon | Hacker News Reader

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Thanks for the reply! So what you're saying is that it's just a "normal" over-the-air software update. I.e. you add some new functionality and then do a full system test of all functions of the software before replacing the entire image?

That makes sense, but is almost a bit disappointing. After all, that is exactly how it works for the boring systems here on earth. From various wired & co articles I had the impression that there was possibly something more; a mechanism that would allow users to send elaborate "commands" to the spacecraft to perform "ad-hoc" tasks at runtime. (What I mean by "ad-hoc" tasks are tasks that are unknown at the time of validation/testing of the software.)

Yes, we can send commands to the spacecraft once it's up there to do thing like modify memory or hard drive contents directly, turn on/off or command payloads and equipment. The full list is pretty exhaustive - anything you could want to be able to do, you can command manually. These things aren't 100% autonomous (though they have autonomous elements in the software).

There is also a way to send pre-programmed task lists to them which are executed sequentially, with delays if necessary.

That kind of thing is in the hands of operations, so it's not usually the job of the software team to test in the normal manner.

Very interesting! Is this kind of command capability (e.g. ability to modify memory contents) something that is usually only available on "non-critical" subsystems, or would you generally expect to also find it on critical components, like the communication or navigation modules?

The ability to modify memory contents is pretty much universal; you can modify things like eeprom contents, the RAM, hard drive, etc. There is no differentiation between critical and non-critical; it's all just fairly critical.

Ground won't send telecommands to a spacecraft to modify a piece of memory without knowing exactly what they're doing first.

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