Yet again the engineers at SpaceX amaze me. It’s hard enough to accelerate tons of payload to several miles a second through a soupy fluid and then coast gracefully in blistering and frigid vacuum. They lost an engine on the way up, at about the worst time as far as aerodynamics stresses. Most other rocket designs would have blown to bits. The whole thing is on video:
Bad Astronomy– You can see a bright spot glowing on the upper right engine, then what looks like shrapnel blowing back as well, so it appears something catastrophic happened to the engine. I can think of many things that could’ve caused this – a crack in the engine bell that failed when it got hot, a faulty valve, something in the pipes – but I’m just spitballing; hopefully the folks at SpaceX will be able to determine the cause from the engine telemetry.
Although this looks scary, the engine nozzles are coated with Kevlar to protect them specifically in case something like this occurs, so the other engines continued working. Also, the onboard computer immediately shut down the failed engine, and then on the fly – literally – recalculated all the needed changes to the thrust of the other engines to compensate. In the end, the first stage boost lasted an extra thirty seconds to cover for the failed engine. It’s important again to note that the Dragon capsule was delivered on orbit and will rendezvous with ISS on Wednesday.