
Ask HN: How does SpaceX verify their simulators? - Rocinantenell
In the past, others have reported that SpaceX execs have stated that one of SpaceX&#x27;s engineering goals is to create a process &quot;where   software could be installed from head at any time and used to immediately fly a mission.&quot;<p>&quot;The most important point stressed was the deeper they got into developing their process, the more focus they spent on building and verifying their simulators and test suite and the less emphasis they put on writing the actual code.&quot;<p>So what I&#x27;m wondering is: Do they have a faster way to verify their simulators other than good old fashioned traditional code reviews and just blowing rockets up more often than the average joe, or does that pretty much cover it?<p>Anyone knowledgable in the subject care to chime in?<p>[0] https:&#x2F;&#x2F;www.linkedin.com&#x2F;pulse&#x2F;spacex-bringing-agile-bdd-final-frontier-timothy-brandt (a little kool-aidish ref, sorry)
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danielvf
I’ve worked with major US car crash testing facilities.

I used to think that crash testing was just a video of the car crashing and an
opportunity to walk around the car afterwords to how the car did. Maybe it
would pass, and maybe it would not.

The reality is that before crash time, a team of guys spend three days wiring
hundreds of accelerometers and other sensors onto the car’s structure at
precise places. During the crash these sensors are recorded at high data
rates, and 3D dataset of the moment by moment deformation of the car’s
internal structure is reconstructed.

This reconstruction is then compared against previous software crash
simulations, and if needed the simulator is updated.

Because the crash simulators are refined across hundreds of crashes, when a
big manufacturer sends a car to be tested, they not only have a pretty good
idea that it will pass, but to a fraction of an inch how much each piece of
metal will bend.

The real design work happens against the simulator, and reality just validates
the simulator.

Similarly, SpaceX has enormous amounts of sensors flying on each launch. This
data lets SpaceX ensure that the simulator version of the rocket matches the
behavior of the real one.

