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At June 28th 2015, the SpaceX flight CRS-7 failed when the Falcon 9 v1.1 rocket exploded minutes after liftoff.

Shotwell said twice during the press conference that Dragon capsule was transmitting after the event. This slow motion video of today's LOV anomaly seems to show the Dragon capsule drifting away before the final conflagration. The debris field seems established already. The Rapid Unplanned Disassembly event of Falcon today occurred at about T+2:18 into its flight, well past maxQ, around 44.5 km up.

If the Dragon did not sustain major damage:

How much could have survived reentry?

How much could have survived oceanic impact?

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As the RUD event occurred during stage 1 flight the Dragon wouldn't having been travelling fast enough to need a heatsheild to survive reentry. (And from 44.5 km it hadn't really gone high enough to be said to be 'reentering', it never really left). The biggest danger to the dragon during the fall would be if it started tumbling.

The conic structure of Dragon is designed to take aerodynamic pressure from the nose on launch, and the base on descent, but a mix of forces in a tumble might have been too much for it. Whether it could have survived a tumbling separation and decent depends on how wide an engineering margin SpaceX used, and given how little we know it's difficult to speculate with any accuracy at this point.

As to your second question:

How much could have survived oceanic impact?

All of it. But it would be in lots of little pieces. It's often said that when you're going at several hundred km/h hitting water is almost the same as hitting concrete, and it's true. Dragon is a beautiful spaceship, but there's no way she could remain intact after that kind of impact.

Of course it probably would have been possible (assuming minimal/no damage) for Dragon to open its parachutes as normal and survive completely intact. I doubt very much that this happened. A failure of this nature, with Falcon destroyed but Dragon intact, was probably never envisaged during the construction of Dragon's software.

The best we can realistically hope for is maybe some hull-panels, a Draco combustion chamber or two, and possibly a battered flight computer.

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    $\begingroup$ @LocalFluff Capsules like Dragon are designed to self-orient heat shield forward, that was also apparent during the pad abort test before parachute deployment (that's why it turned belly upwards, it still had upwards velocity component after separation), but is also a necessity during reentry. Terminal velocity should be documented somewhere as speed prior to drogue chute deployment during reentries, I'll check. Or, ask a question... :) $\endgroup$ – TildalWave Jun 28 '15 at 21:49
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    $\begingroup$ @LocalFluff It says here that Dragon slows down to under 240 m/s (864 km/h or Mach 0.7) before drogue chute deployment, at an altitude of about 13.7 km (a bit over tropopause for today's latitude by standard atmospheric model, roughly 3 psi). Speed should be quite a bit lower than that in even denser atmosphere (14.7 psi) just before splashdown tho. $\endgroup$ – TildalWave Jun 28 '15 at 22:04
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    $\begingroup$ @TildalWave The self-orientation of the Dragon depends on whether it is attached to the service module or not, right? At least that seems to be the case for (crewed) Dragon 2, considering the pad abort test. $\endgroup$ – LocalFluff Jun 29 '15 at 6:52
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    $\begingroup$ "RUD Event" = breakup. That's the funniest euphemism I've heard in a while. $\endgroup$ – WetSavannaAnimal Jul 3 '15 at 9:56
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    $\begingroup$ "Working with USAF and NASA on flight data, which revealed first stage was nominal. Dragon continued to communicate until it went over horizon after failure. Dragon could have been saved with right software. Now including contingency software to allow Dragon to save itself. The Dragon continued to communicate until below horizon. "Parachute would have saved Dragon." Software to allow deployment of parachutes in the event of launch failure will be included in next Dragon flight."-Elon Musk, On a conference call with the media $\endgroup$ – T.J. Tarazevits Jul 21 '15 at 9:38
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This was too long to post as a comment:

The investigation also revealed that if the Dragon had deployed its parachutes before falling into the ocean, the spacecraft would have survived. The software in this cargo version of Dragon (Dragon 1), Musk explained, is inert on ascent and was not programmed to release the parachute in the event of a failure. Software in the version of Dragon under development for taking people into space (Dragon 2 or Crew Dragon) is programmed to do just that. Musk said they would be working on software fixes to ensure that the Dragon 1 cargo spacecraft can do what it needs to survive. “We could have saved Dragon if we had the right software there,” he said.

Failed Strut Likely Cause of Falcon 9 Failure, But Investigation Continues

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  • $\begingroup$ Why couldn't they have manually commanded the parachutes to deploy? $\endgroup$ – Sean Mar 31 at 2:59
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SpaceX received Dragon telemetry until it disappeared below the horizon:

In addition, the Dragon spacecraft not only survived the second stage event, but also continued to communicate until the vehicle dropped below the horizon and out of range.

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