I read further into this. This detail on the crash (stolen from Wikipedia) is particularly macabre:

The crew cabin, made of reinforced aluminum, was a particularly robust section of the shuttle.[25] During vehicle breakup, it detached in one piece and slowly tumbled into a ballistic arc. NASA estimated the load factor at separation to be between 12 and 20 g; within two seconds it had already dropped to below 4 g and within 10 seconds the cabin was in free fall. The forces involved at this stage were likely insufficient to cause major injury.

At least some of the crew were likely alive and at least briefly conscious after the breakup, as the four recovered Personal Egress Air Packs (PEAPs) on the flight deck were found to have been activated.[26] Investigators found their remaining unused air supply consistent with the expected consumption during the 2 minute 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. Fellow astronaut Richard 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 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.[27]

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 have not happened all at once.

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.[22]

On July 28, 1986, NASA's Associate Administrator for Space Flight, former astronaut Richard H. Truly, released a report on the deaths of the crew from the director of Space and Life Sciences at the Johnson Space Center, Joseph P. Kerwin. A medical doctor and former astronaut, Kerwin was a veteran of the 1973 Skylab 2 mission. According to the Kerwin Report:

The findings are inconclusive. The impact of the crew compartment with the ocean surface was so violent that evidence of damage occurring in the seconds which followed the disintegration was masked. Our final conclusions are:

the cause of death of the Challenger astronauts cannot be positively determined;

the forces to which the crew were exposed during Orbiter breakup were probably not sufficient to cause death or serious injury; and

the crew possibly, but not certainly, lost consciousness in the seconds following Orbiter breakup due to in-flight loss of crew module pressure.[22]

Some experts believe most if not all of the crew were alive and possibly conscious during the entire descent until impact with the ocean. Astronaut and NASA lead accident investigator Robert Overmyer said, "I not only flew with Dick Scobee, we owned a plane together, and I know Scob did everything he could to save his crew. Scob fought for any and every edge to survive. He flew that ship without wings all the way down... they were alive."[25]