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How to avoid a BSOD on your 2B dollar spacecraft

clarkwakeland.com

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Re: How to avoid a BSOD on your 2B dollar spacecraft

#51

Post by topspin »

linebeck wrote: post #36

Author here: I should clarify the satellite is not running Windows. Instead, it’s running its own custom OS written in C called Flight Software (FSW) specifically designed for the satellite onboard computer. Re-reading the post, I see how the title, my analogies, and poor attempts at humor would give the incorrect description of what’s happening with the satellite when it enters safemode. I’ll amend the post soon. Th…

I understood you were using an analogy. Didn't even occur to me that Windows was actually being used.

However, I did come away thinking there are other dysfunctions at play in all of this. Perhaps an excessive amount of wheel re-inventing.

Re: How to avoid a BSOD on your 2B dollar spacecraft

#52

Post by Jtsummers »

linebeck wrote: post #49
barbegal wrote: post #39

Earlier quoted context omitted.

Could I ask you to clarify why avoiding safemode is so important? In a non satellite system safemode means everything is driven to a safe state which is fine during testing in the lab. Also do you not run these tests in an even more simulated environment where there is only the flight computer and no real hardware at all?

Having discussed this same question with the more experienced members of my team, the only conclusion I can draw is that the customer (US Government) is incredibly risk averse. Any unexpected entry into safemode would require a report, multiple meetings with the customer, and them being pretty angry. Their line of reasoning seems to be "Safemode->Something is wrong->Why is something wrong? We're not paying you to be…

> Any unexpected entry into safemode would require a report, multiple meetings with the customer, and them being pretty angry. Their line of reasoning seems to be "Safemode->Something is wrong->Why is something wrong? We're not paying you to be wrong". I'm personally of the opinion that safemode isn't that bad. It's fully recoverable and shows the system is working properly.

To the last part first: Good that safe mode kicked in and did the right thing, but now what? What caused it to enter safe mode in the first place?

That's why they care when it happens. If they don't know why it's entering safe mode, they can't correct the actual problems in the system.

Re: How to avoid a BSOD on your 2B dollar spacecraft

#53

Post by lisper »

GlenTheMachine wrote: post #22

Thee are a bunch of comments here asking why one would run Windows on a spacecraft. I am a spacecraft engineer. I don’t see anything in the linked article indicating that they are actually running Windows - the BSOD claim is tongue-in-cheek, or at least that’s how I read it. I also don’t know of anyone anywhere that runs Windows on a spacecraft, with the exception of laptops used by astronauts. Typically one runs vxW…

The author of TFA clarifies here:

https://news.ycombinator.com/item?id=41651715

TL;DR: the spacecraft is indeed not running Windows. It's running a custom OS written in C.

Re: How to avoid a BSOD on your 2B dollar spacecraft

#55

Post by XorNot »

zanthras wrote: post #44
GlenTheMachine wrote: post #22

Thee are a bunch of comments here asking why one would run Windows on a spacecraft. I am a spacecraft engineer. I don’t see anything in the linked article indicating that they are actually running Windows - the BSOD claim is tongue-in-cheek, or at least that’s how I read it. I also don’t know of anyone anywhere that runs Windows on a spacecraft, with the exception of laptops used by astronauts. Typically one runs vxW…

Linux(with realtime patch) is used very heavily in spacecraft by Spacex. So both in terms of high visibility/important/danger (dragon 2) and high count (starlink) it is very widely used. citation https://old.reddit.com/r/spacex/comments/ncj4vz/we_are_the_s...

I wonder how the integration of PREEMPT_RT is going to affect that technology stack going forwards (I imagine slowly, but it's there now).

Re: How to avoid a BSOD on your 2B dollar spacecraft

#56

Post by yndoendo »

XorNot wrote: post #55
zanthras wrote: post #44

Earlier quoted context omitted.

Linux(with realtime patch) is used very heavily in spacecraft by Spacex. So both in terms of high visibility/important/danger (dragon 2) and high count (starlink) it is very widely used. citation https://old.reddit.com/r/spacex/comments/ncj4vz/we_are_the_s...

I wonder how the integration of PREEMPT_RT is going to affect that technology stack going forwards (I imagine slowly, but it's there now).

Save costs by integration with the new feature or increasing cost with maintaining a custom kernel branch in the long run.

Re: How to avoid a BSOD on your 2B dollar spacecraft

#57

Post by axus »

Jtsummers wrote: post #52
linebeck wrote: post #49

Earlier quoted context omitted.

Having discussed this same question with the more experienced members of my team, the only conclusion I can draw is that the customer (US Government) is incredibly risk averse. Any unexpected entry into safemode would require a report, multiple meetings with the customer, and them being pretty angry. Their line of reasoning seems to be "Safemode->Something is wrong->Why is something wrong? We're not paying you to be…

> Any unexpected entry into safemode would require a report, multiple meetings with the customer, and them being pretty angry. Their line of reasoning seems to be "Safemode->Something is wrong->Why is something wrong? We're not paying you to be wrong". I'm personally of the opinion that safemode isn't that bad. It's fully recoverable and shows the system is working properly. To the last part first: Good that safe mod…

"Safemode is when all non critical functions are automatically shut down and the satellite becomes entirely focused on generating power by pointing its solar panels towards the Sun and trying to reestablish any communication that was lost."

The non-critical functions are all the things the customer actually bought the satellite for. Cool that it's still alive, but now the Space Internet / death lasers / etc. are offline.

Re: How to avoid a BSOD on your 2B dollar spacecraft

#58

Post by foobar1962 »

exe34 wrote: post #16
anonzzzies wrote: post #12

Earlier quoted context omitted.

Anyway, I was responding to someone who wouldn't run either on a spaceship so I still would like to know what they would want to run. I am from a formal verification school of thought, so I would want something sel4.

I'd want manual backup pushbuttons.

And another box close enough so the CD tray can press them when it opens.

Re: How to avoid a BSOD on your 2B dollar spacecraft

#59

Post by nicce »

TrueDuality wrote: post #42
GlenTheMachine wrote: post #22

Thee are a bunch of comments here asking why one would run Windows on a spacecraft. I am a spacecraft engineer. I don’t see anything in the linked article indicating that they are actually running Windows - the BSOD claim is tongue-in-cheek, or at least that’s how I read it. I also don’t know of anyone anywhere that runs Windows on a spacecraft, with the exception of laptops used by astronauts. Typically one runs vxW…

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.

Every Starlink runs with Linux.

The license list is a bit long:

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

Re: How to avoid a BSOD on your 2B dollar spacecraft

#60

Post by MichaelZuo »

nicce wrote: post #59
TrueDuality wrote: post #42

Earlier quoted context omitted.

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.

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.
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