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In space, no one can hear you kernel panic (2020)

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Re: In space, no one can hear you kernel panic (2020)

#21

Post by superxpro12 »

wongarsu wrote: post #19
KurSix wrote: post #14

The contrast with modern software development is striking. Today we often rely on fast iteration and patching problems in production. Spacecraft software is the opposite

On the other hand a lot of SpaceX's success can be attributed to applying modern software development methodology on spacecraft. They are very much doing agile development, betting on velocity enabling fast iteration. That has lead to some of the best rockets ever developed, and the largest satellite constellation by far. But part of the secret sauce is creating situations where you can take risks. Traditionally anyt…

I recall an early deep-dive into their safety architecture on the falcon 9, which was basically "throw 3 COTS processors at it and reboot anything that doesnt work, and fail fast during development". I remember they explicitly avoided rad-hard processors as well.

I would love to update myself if anyone has a good source.

For better or worse, it's hard to argue with results.

Re: In space, no one can hear you kernel panic (2020)

#22

Post by whattheheckheck »

superxpro12 wrote: post #21
wongarsu wrote: post #19

Earlier quoted context omitted.

On the other hand a lot of SpaceX's success can be attributed to applying modern software development methodology on spacecraft. They are very much doing agile development, betting on velocity enabling fast iteration. That has lead to some of the best rockets ever developed, and the largest satellite constellation by far. But part of the secret sauce is creating situations where you can take risks. Traditionally anyt…

I recall an early deep-dive into their safety architecture on the falcon 9, which was basically "throw 3 COTS processors at it and reboot anything that doesnt work, and fail fast during development". I remember they explicitly avoided rad-hard processors as well. I would love to update myself if anyone has a good source. For better or worse, it's hard to argue with results.

Imagine trying to explain to 1960s tax payers were going to build and blow up multiple rockets for research velocity and dev feedback loops

Re: In space, no one can hear you kernel panic (2020)

#25

Post by budman1 »

somat wrote: post #10

"From the dawn of the Space Age through the present, NASA has relied on resilient software running on redundant hardware to make up for physical defects, wear and tear, sudden failures, or even the effects of cosmic rays on equipment." An interesting case study in this domain is to compare the Saturn V Launch Vehicle Digital Computer with the Apollo Guidance Computer Now the LVDC, that was a real flight computer, tri…

It all depends on the failure.

A transient bit failure in digital circuits? Then reboot and away you go.

A coding / algorithmic defect. Reboot and you are back in the same place.

Also, the AGC was directly interfaced to an astronaut. They could decide to ignore erroneous outputs from the AGC.

Re: In space, no one can hear you kernel panic (2020)

#26

Post by budman1 »

superxpro12 wrote: post #21
wongarsu wrote: post #19

Earlier quoted context omitted.

On the other hand a lot of SpaceX's success can be attributed to applying modern software development methodology on spacecraft. They are very much doing agile development, betting on velocity enabling fast iteration. That has lead to some of the best rockets ever developed, and the largest satellite constellation by far. But part of the secret sauce is creating situations where you can take risks. Traditionally anyt…

I recall an early deep-dive into their safety architecture on the falcon 9, which was basically "throw 3 COTS processors at it and reboot anything that doesnt work, and fail fast during development". I remember they explicitly avoided rad-hard processors as well. I would love to update myself if anyone has a good source. For better or worse, it's hard to argue with results.

maybe they are in a 'sweet spot'. spaceX is not on the bleeding edge of anything; rather they are optimizing existing solutions. incremental design changes, in a problem domain that has been studied for decades, and is well known, will provide results. "web dev" for an e-commerce platform will show great improvement with an agile, move fast development process.

change the fundamental nature of the propulsion, or a step change in the technology, and it may be more effective to go with an engineered approach.

'engineered approach' --> before the item is built, a very good idea of how it is going to work has been determined. using math and science.

Re: In space, no one can hear you kernel panic (2020)

#27

Post by anonymous_user9 »

somat wrote: post #10

"From the dawn of the Space Age through the present, NASA has relied on resilient software running on redundant hardware to make up for physical defects, wear and tear, sudden failures, or even the effects of cosmic rays on equipment." An interesting case study in this domain is to compare the Saturn V Launch Vehicle Digital Computer with the Apollo Guidance Computer Now the LVDC, that was a real flight computer, tri…

The command module and lunar module each had one AGC. (The lunar module did include a simpler backup computer called the Abort Guidance System.)

I think this is because an AGC failure is recoverable in most phases of flight, while an LVDC failure is not.

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