The Challenger's crew did not immediately die when the rockets blew up. In fact, the cabin was found in tact at the bottom of the ocean and there are indications the pilot was conscious and furiously working to survive right up until it hit the water.

(http://www.autoadmit.com/thread.php?thread_id=4631190&forum_id=2#40970034)

I mean, yeah I guess that stops short of explicitly spelling out in words 'they were all alive and screaming in abject terror the whole way down,' but I don't really think they were going to great lengths to hide the ball on that. I felt like the inference was fairly clear.

(http://www.autoadmit.com/thread.php?thread_id=4631190&forum_id=2#40970852)

At least some of the crew were alive and at least briefly conscious after the breakup, as three of the four recovered Personal Egress Air Packs (PEAPs) on the flight deck were found to have been activated.[31] These were those of Judith Resnik, mission specialist Ellison Onizuka, and pilot Michael J. Smith.[32] The location of Smith's activation switch, on the back side of his seat, likely indicated that either Resnik or Onizuka activated it for him. Astronaut Mike Mullane wrote that "There had been nothing in our training concerning the activation of a PEAP in the event of an in-flight emergency. The fact that Judy or El had done so for Mike Smith made them heroic in my mind."[32] Investigators found their remaining unused air supply consistent with the expected consumption during the 2-minute-and-45-second post-breakup trajectory.

While analyzing the wreckage, investigators discovered that several electrical system switches on pilot Mike Smith's right-hand panel had been moved from their usual launch positions. Mike Mullane wrote, "These switches were protected with lever locks that required them to be pulled outward against a spring force before they could be moved to a new position." Later tests established that neither the force of the explosion nor the impact with the ocean could have moved them, indicating that Smith made the switch changes, presumably in a futile attempt to restore electrical power to the cockpit after the crew cabin detached from the rest of the orbiter.[33]

Whether the crew members remained conscious long after the breakup is unknown, and largely depends on whether the detached crew cabin maintained pressure integrity. If it did not, the time of useful consciousness at that altitude is just a few seconds; the PEAPs supplied only unpressurized air, and hence would not have helped the crew to retain consciousness. If, on the other hand, the cabin was not depressurized or only slowly depressurizing, they may have been conscious for the entire fall until impact. Recovery of the cabin found that the middeck floor had not suffered buckling or tearing, as would result from a rapid decompression, thus providing some evidence that the depressurization may not have happened suddenly.

NASA routinely trained shuttle crews for splashdown events, but the cabin hit the ocean surface at roughly 207 mph (333 km/h), with an estimated deceleration at impact of well over 200 g, far beyond the structural limits of the crew compartment or crew survivability levels, and far greater than almost any automobile, aircraft, or train accident. The crew would have been torn from their seats and killed instantly by the extreme impact force.[25]

(http://www.autoadmit.com/thread.php?thread_id=4631190&forum_id=2#40970133)

Just do catastrophic depressurization during re-entry, bro.

(http://www.autoadmit.com/thread.php?thread_id=4631190&forum_id=2#40970643)