9 ms·

Ugh, now imagining trying to debug a really sneaky bug that costs $100 million every time it triggers...

• kabdib 11y ago
  I recommend Henry S.F. Cooper's book _The Morning Star_, which is about debugging hardware failures and OS race conditions on a spacecraft orbiting Venus. (There are similar stories about debugging stuff on the various Martian rovers, but Cooper's book is a very good treatment...).
  • twistedpair 11y ago
    It's actually "The Evening Star" Grab it used for $0.75 http://product.half.ebay.com/The-Evening-Star-Venus-Observed-by-Henry-S-Jr-Cooper-1993-Hardcover/145419 http://product.half.ebay.com/The-Evening-Star-Venus-Observed...
  • alphadevx 11y ago
    I think you mean The Evening Star, marvelous book: http://amzn.to/1Hq8TcX http://amzn.to/1Hq8TcX
  • kabdib 11y ago
    I stand corrected. Written in haste. Cooper is a wonderful writer, I've got all of his books :-)
• drzaiusapelord 11y ago
  Stupid question perhaps, but don't we have the ability to 100% simulate the rocket physics and the code it runs on in a simulation environment? Or are they just punching out code, shoving it onto rocket controllers, and testing in the real world? I'm curious as to the QA system used here. I imagine with proper simulation this should have been catchable. I wonder if SpaceX's low cost approach means cutting certain corners and situations like these where catchable issues make it into the wild because of the difficulty of rocketry in general with the added difficulty of cheap spaceflight tacked on. I really hope they didn't just find themselves in a STS-51-L moment where it'll take months to truly iron out the root issues. Thank goodness there was no loss of life and SpaceX's stack isn't man rated yet.
  • nkoren 11y ago
    Rocket physics are actually relatively trivial and, yes, can be fully simulated (and are). Rocket plumbing is always the hard part. Perhaps the threads on some connector got stripped as it was screwed together. Perhaps there was a manufacturing flaw or unexpected bit of corrosion in a particularly vital bolt. Perhaps a bit of contamination in a fuel line caused something catalytic to happen. Perhaps a bit of excess H20 condensation in a LOX valve caused an ice dam to form and the supply line to over-pressurise. These are the sort of problems which bring rockets down: really damned complicated plumbing problems.
    • drzaiusapelord 11y ago
      I guess my point is, can we do a full simulation of every screw, material, plumbing, liquid dynamics, weather dynamics, etc and augment those with known fail scenarios and other fuzzy data to build out a real world KSP that predicts fails reliably? We should understand how things like corrosion and condensation work on a rocket engine. Considering the low cost of incredible amounts of CPU power, granular level simulation is possible on a certain level today if someone wanted to create it. We certainly see this kind of thing with stealth technology, where we can simulate every permutation of near every radar photon hitting the various surfaces of planes with various materials, scenarios, temperatures, etc. I imagine this level of simulation might not be entirely feasible yet. Maybe for the lack of trying or budget. In a growth industry or one powered by both commercial and technical pressures, it may be difficult to sit down and build something like this out. From a more practical point of view, it may make sense to just let things explode than spend years running expensive simulations instead of building things, launching, and collecting paychecks.
      • ahelwer 11y ago
        The radar technique is possible because of the trivially-parallizable finite-difference time domain method, which most certainly does not simulate every photon (this may have been a rhetorical flourish on the part of wherever you learned this; FDTD curiously has zero error term). Nor would it simulate a wave hitting from every direction; each of those would be a separate run of the simulation.