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Comment by TrueDuality | Hacker News Reader

Seconding the vxWorks and bare metal. Never seen Windows or Linux on a satellite bus. Haven't really touched payloads but I've seen some wonky things shipped to orbit by universities and not all them have been cubesat student projects.

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Linux on a satellite bus is definitely up and coming. For example ESA's OPS-SAT ran the NanoSat MO Framework (https://nanosat-mo-framework.github.io/), written in Java and running on an ARM Linux OBC. It also makes a lot of sense for payload computers.

I'm working on a Linux distribution for space applications that addresses some of the pain points (application deployment, software update & memory-safe implementations of typical space protocols like CCSDS/PUS). If all goes to plan it will fly on a 1U CubeSat tech demonstrator this year, a cybersecurity research 1U CubeSat next year, and a 2U high performance satellite ... later. :)

Every Starlink runs with Linux.

The license list is a bit long:

https://www.starlink.com/assets/pdfs/Starlink-Open-Source-Co...

It's surprising they didn't pick a RTOS.

Why? What benefit would that give them?

I can't tell if this a serious comment or not, but they need an OS with realtime guarantees. They have claimed to use linux in a rtos configuration, also probably have a redundancy and voting-based failover system.

I can't tell if this is a serious answer to the question or not, as you have answered it in terms of the question: "why the need for RTOS? -> because they need RTOS". Stop wasting time with replies like this that add no value.

If you can’t understand why the control system for SOMETHING GOING TO SPACE needs an RTOS then I can’t even begin to have a conversation with you

They did.

How? That was a very recent change to linux.

It was merged to mainline Linux last week. The patches have been usable for many years if you compile a custom kernel.

It’s not quite Linux anymore if it’s a custom kernel…

Yeah, usually it has a vendor brand slapped on it tbqh

Why? I doubt that Linux controls everything. I imagine it's used for the core higher level functions of the satellites themselves, but I'm sure processes running in Linux will eventually comms with lower level hardware that is indeed running an rtos or similar.

In the same way that any pi project should really use i2c or spi to comms with hardware that's more purpose designed.

that doesn't state what uses linux, angular.io is also on there

That's likely software for the receiver/router/CPE that customers use, since it's being distributed they have to satisfy license obligations for it.

Software actually running on satellites isn't being distributed, so there's no license obligations there (unless it's AGPL, ha!)

It includes that software too, but they have claimed that they use Linux, so I would assume that some software is from the satellite itsef as well. It is still not clear ”what” obligations you have for a piece in the space.

Yeah, why would a satellite have angular...

I've used Linux on the payload processor computer of a spacecraft so I know it happens :P

I've also worked with a payload running Windows Embedded.

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