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What computer and software is used by the Falcon 9? (2015)

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Re: What computer and software is used by the Falcon 9? (2015)

#121

Post by arexxbifs »

BiteCode_dev wrote: post #116
jonplackett wrote: post #108

Earlier quoted context omitted.

Well, that Mars rover missed its target because they got their units of measurement mixed up. https://www.latimes.com/archives/la-xpm-1999-oct-01-mn-17288... So, don’t feel too bad...

It does feel better knowing my mistake didn't cost $125-million dollars. Is there a book that lists many bugs and weird IT stories? Like the 500km email or the FileNotFound boolean.

A selection of dangerous and/or expensive bugs from space flight alone:

https://en.wikipedia.org/wiki/List_of_software_bugs#Space

I'm sure there's plenty more, albeit of lesser significance.

Re: What computer and software is used by the Falcon 9? (2015)

#122

Post by BiteCode_dev »

arexxbifs wrote: post #121
BiteCode_dev wrote: post #116

Earlier quoted context omitted.

It does feel better knowing my mistake didn't cost $125-million dollars. Is there a book that lists many bugs and weird IT stories? Like the 500km email or the FileNotFound boolean.

A selection of dangerous and/or expensive bugs from space flight alone: https://en.wikipedia.org/wiki/List_of_software_bugs#Space I'm sure there's plenty more, albeit of lesser significance.

Thanks

Re: What computer and software is used by the Falcon 9? (2015)

#123

Post by arexxbifs »

BiteCode_dev wrote: post #99
jonplackett wrote: post #95

Earlier quoted context omitted.

Imagine if everyone on earth was as productive as those 35 people.

It reminds me of this olognion piece: https://www.theolognion.com/unreal-engine-5-is-meant-to-ridi... That's not just hilarious, that's also pretty close to how I feel most of the time. I mean, some people have built the Airbus A380. On the other hand, last week, I created a test DB with the user "test" and the password "test". I couldn't connect to it, and after a long debugging session, noticed I misspelled "test".…

I appreciate it's a joke, kicking at open doors at that. Still, here's what one dude coded in JavaScript on his spare time a few years ago: https://www.pouet.net/prod.php?which=71881

Re: What computer and software is used by the Falcon 9? (2015)

#124

Post by zo1 »

Simulacra wrote: post #89

I’m really curious what language the telemetry data is written in. Does anyone know what the historically preferred language is?

Probably running Node Javascript (or Typescript), transmitted in JSON over a restful API, hosted on a K8s cluster using Docker containers. Also, the JSON payload has a formal schema in the form of JSonSchema V5. /s

On a more serious note. Some of the amazing stuff that the SpaceX team are accomplishing really puts into perspective the day to day work I and others here do.

Re: What computer and software is used by the Falcon 9? (2015)

#126

Post by coss »

elteto wrote: post #83
exikyut wrote: post #72

Earlier quoted context omitted.

Very curious, how is state persisted where non-volatile storage is needed, and how is that persistence structured?

It is never persisted outside of RAM. The flight computers are never powered off during a mission. You rely on two flight computers to always be functioning, that’s why the system is one-fault redundant. You can think as each string being “functional“: given the same set of inputs you expect the same set of outputs.

What happens if some anomaly happens where the shuttle loses power for a second?

Re: What computer and software is used by the Falcon 9? (2015)

#127

Post by heisenzombie »

bmitc wrote: post #109
qchris wrote: post #100

Knowing that the ground control software is written in LabView is one of the more disappointing things I've read recently. I did a bunch of test engineering during co-ops during college, including multiple "codebases" of LabView, plus the normal class coursework and research lab instrumentation. I hate LabView, to the degree that I made a commitment never to apply to a job that has it's use as one of the requirements…

How well do you actually know LabVIEW? Have you ever used its object-oriented system, actor framework, network streams, or get/set control value by indices (a feature actually implemented for SpaceX) functionalities? These are all things a professional LabVIEW engineer will be familiar with and use. The fact that a system didn't use these means it's either seriously outdated or the person writing it wasn't aware. It…

I have written and maintained a piece of testing/control software. It was originally horrible “old” spaghetti Labview. I maintained it for a while then wrote a replacement with Labview’s actor framework. I agree that the AF seems to be the only reasonable way to write certain kinds of larger application. However, the actor framework was, for me, just barely good enough to be usable.

- The debugging story is very bad: There were community efforts to write some tools to help, but they amounted to downloading software from a forum post.

- Development is incredibly tedious: Creating a new actor, or message, or (god forbid) implementation of an abstract message. They all take SO many clicks across lots of files in a slow IDE. Tedious and error prone.

- Distributing actors across nodes is not supported by the framework.

- There is no concept of supervision trees, so if you want “let it crash” robustness, you’ll be writing that yourself

I wish it were different, because at its heart I kind of love the idea of a strongly-typed dataflow language.

Edit: I want to point out that despite how personally ugly I found the experience, I’m not sure there was a better choice. I would love to have used Elixir, but what (non-software) engineering company can hire for that?

Re: What computer and software is used by the Falcon 9? (2015)

#128

Post by cbanek »

erikbye wrote: post #38

SpaceX has had a booth at GDC at least two times, they attend in order to recruit game developers (programmers), as they feel these programmers work with a lot of the same constraints they do in terms of resources and experience with real-time, performant systems, etc.

It's true, I was there! (And I was a gamedev previously). Although you forgot crunch time which I think is the real required experience. ;)

Re: What computer and software is used by the Falcon 9? (2015)

#129

Post by jchw »

microcolonel wrote: post #56
jchw wrote: post #20

Earlier quoted context omitted.

Once you decide that absolute reliability is unattainable, you can instead aim for sufficient redundancy. It’s not perfect, but with enough safe guards in place it may very well be good enough.

Software is not always like hardware though: the same software failure can cascade across redundant instances rapidly just as easily as it affects the primary.

The same hardware failure can cascade too; redundancy alone is not a panacea, you need some safeguards. Ideally, nothing should fully trust anything else.

Re: What computer and software is used by the Falcon 9? (2015)

#130

Post by vertex-four »

scotty79 wrote: post #118
vertex-four wrote: post #66

Earlier quoted context omitted.

There's... a large number of languages with both of those features.

Could you name few better than js?

In the context of writing reliable software for a spacecraft? Pretty much anything with a reasonable type system, for a start. Maybe C#, or some reasonable subset of C++20, or Rust. Maybe Reason or OCaml.
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