The seven crew members of the space shuttle Challenger probably remained conscious for at least 10 seconds after the disastrous Jan. 28 explosion and they switched on at least three emergency breathing packs, the National Aeronautics and Space Administration said Monday.
At a news conference, NASA officials for the first time made public information showing that the Challenger crew probably not only lived through the initial blast but understood the seriousness of the situation enough to activate the emergency air systems.
The release of information learned from the crew cabin salvage operation, in addition to a transcript of crew compartment conversation, contradicted an earlier July 17 space agency announcement that the crew probably had no knowledge of its impending doom.
In a prepared statement, the agency said Monday that a subsequent full analysis of tape recordings in the crew compartment showed "the first potential indication of awareness."
"Uh-oh," Challenger pilot Michael J. Smith said 73 seconds after takeoff. It was the last sound of the crew recorded by the intercom in the shuttle's cabin. The intercom, as well as the air-to-ground communications, shut off at the time of the explosion.
The explosion occurred when hot gases from the Challenger's right solid booster burned through a seam in the multi-sectioned rocket, sending a jet of heat toward the shuttle's huge fuel tank.
"It's my guess that, at that point, there was awareness on the part at least of the commander and pilot because that was the moment of the explosion," said Rear Adm. Richard H. Truly, NASA's associate administrator for spaceflight.
Restored tapes indicated conversation only among the four crew members who sat on the flight deck: Commander Francis R. (Dick) Scobee, Smith and mission specialists Ellison S. Onizuka and Judith A. Resnik.
Unlike the flight deck, which had a voice-activated intercom system, the middeck system required crew members to push a button to be recorded. Crew members Sharon Christa McAuliffe, Ronald E. McNair and Gregory B. Jarvis, who sat on the middeck, followed NASA procedure and did not record themselves, officials said. However, they were able to hear the conversation of others.
Dr. Joseph P. Kerwin, director of life sciences at NASA's Johnson Space Center in Houston, said the explosion that tore the crew compartment from the rest of the orbiter probably would not have killed or even seriously injured the crew members.
"Medical analysis indicates that these accelerations are survivable and that the probability of major injury to crew members is low," Kerwin wrote in a report to Truly.
Loss of Cabin Pressure
In his report, Kerwin said the crew "possibly but not certainly" lost consciousness in the seconds after the orbiter began breaking apart because of loss of pressure in the crew cabin. He said the amount of time which the crew maintained consciousness "depends on the rate at which the crew module lost pressure, and that depends on the size of the hole in the crew module," which could not be ascertained from the wreckage.
The explosion occurred at an altitude of 48,000 feet, and the crew cabin continued to a peak of 65,000 feet, Kerwin said.
"The pressures there are so low that even with a supplemental breathing supply, the time of useful consciousness would vary between approximately 6 and 15 seconds," Kerwin said at the news conference. "So the number of seconds that the crew may have retained consciousness would be a function of how rapidly the crew module lost pressure."
When asked after the news conference if he meant that the crew probably remained conscious for at least 10 seconds, Kerwin replied: "Yes."
He noted at the press conference that he could not rule out the possibility that they may have been alive until the crew cabin hit the water.
None Survived Impact
The compartment crashed into the water nearly intact 2 minutes and 45 seconds after the explosion. Traveling at a speed of 207 m.p.h., none of the crew members inside the compartment could have survived the impact, Kerwin said.
He noted that the cause of death could not be determined and medical examiners from Armed Forces Institute of Pathology "could not determine whether in-flight lack of oxygen occurred."
Each crew member had access to a pack that provided about five minutes of breathing air. The pack only could be activated manually by a crew member. Unlike the other crew members, Scobee and Smith could not have reached their packs without getting up from their seats. Officials said an inspection of the crew cabin wreckage showed that the crew members were strapped into their seats when they hit the ocean.
Salvage teams recovered four air packs at the bottom of the ocean and determined that three of them had been activated. The unused pack belonged to Scobee, NASA officials said. Two of the three used packs could not be identified. The third belonged to Smith. Either Onizuka or Resnik, who sat behind Smith, must have switched on his emergency air supply for him, Truly said.
Kerwin said air is drawn from the packs on demand, whether the person was conscious or unconscious. He said an inspection of two of the air packs, including the one belonging to Smith, showed they were three-quarters to seven-eighths empty at the time of impact.
Air Use Unclear
It is unclear why so much air would have been used since NASA said the crew could not have survived that long. A space agency spokeswoman theorized that the loss of cabin pressure might have contributed to the rapid depletion of the air.
Until 73 seconds, the conversation of the crew appears to have been normal. One second after takeoff, Smith said: "Here we go." Ten seconds later, he said: "Go, you mother." Resnik, 15 seconds after takeoff, said what NASA transcribed as, "(Expletive) hot." At 19 seconds, Smith mentioned the wind shears that rocked the shuttle. "Looks like we've got a lotta wind here today." At 60 seconds, he said, "Feel that mother go."
Truly said NASA officials initially could not make out Smith's final utterance of concern because of a garble in the tapes and that is why the space agency announced the crew apparently had no indication of their impending deaths.
Truly said the families of the crew members have been advised of the contents of the tapes. He noted that he has always been concerned about the delicacy of releasing information about the crew's final seconds of life and the possible impact it might have on the families.
NASA first announced that tape recordings had been restored after Smith's widow filed a $15.1-million negligence claim against NASA. The claim maintains that Smith must have been "thrown about" in the spacecraft before his death and therefore must have anticipated it.