KENNEDY SPACE CENTER, Fla. — New photographs of the space shuttle Challenger's disastrous launching show a thick puff of black smoke emerging near the right solid rocket booster just 1.8 seconds after liftoff.
The photographs, released by the National Aeronautics and Space Administration on Thursday, provide the first clear indication that something was amiss from the instant the shuttle left the pad on Jan. 28.
In addition, they provide new evidence of a possible failure in a seal between the segments of the solid fuel booster, pinpointed in recent weeks as the most likely cause of the subsequent explosion.
Smoke in Seal Area
Still photos and videotapes show the smoke belching from a point at or slightly below the lower aft seal area of the right booster almost immediately after ignition of the booster engines.
The smoke appears at about the same point where an unusual plume of fire was seen in earlier photos emanating from the booster 59 seconds into the launching.
"It shows something very unusual. We have not seen anything like that before," NASA spokesman Jim Mizell said.
Officials from NASA and a 12-member presidential commission investigating the accident at the Kennedy Space Center reviewed tapes Thursday from all previous launchings before releasing the new photos. None of them showed any smoke, Mizell said.
A NASA task force gathering data for the commission "is continuing to conduct detailed analyses to determine the exact time, origin, dimensions and other characteristics of the smoke," the agency said in a statement.
NASA officials refused to speculate Thursday about the potential causes of the smoke.
No Abnormalities in Data
The agency said it has still not ruled out any potential cause for the conflagration that enveloped the shuttle 73 seconds after liftoff. But the NASA task force said that "very preliminary data evaluation" of the orbiter and its main engines shows "normal operations."
That again focuses attention on the solid rocket booster and, in particular, on the synthetic rubber seals placed between the various segments of the booster.
NASA officials have known for some time that one of the two rubber O-rings sealing each seam between booster segments could become unseated after liftoff, leaving only the quarter-inch primary O-ring in the assembly to prevent flame from breaching the rocket case.
NASA officials have said they believed it safe to launch anyway because the rings had held up under tremendous testing pressures.
But a former solid rocket consultant for Morton Thiokol, manufacturer of the boosters, speculated Thursday that the puff of smoke could indicate a failure of the seals--particularly during the 38-degree temperature on the morning of the launching.
Although he had not yet seen the new photographs, Gary Flandro, a professor at Georgia Institute of Technology, said the smoke provides stronger evidence of an early failure of one of the seals rather than a burn-through in the casing of the rocket, which would take much longer.
Because of the cold weather on the morning of the launching, the O-rings would have been relatively brittle and could have snapped during ignition of the rocket motor, when the booster builds to 3.3 million pounds of thrust within a fraction of a second.
"That (the smoke) is what you would expect if there had been a rupture of the seals," Flandro said.
"That hole would have gotten larger," he said, accounting for the plume of flame seen in later photos.
Another possible explanation offered by other booster experts is that the smoke could have emerged from a test port in the joint, an area probed with a tube during pressure tests and protected later with a bolt.
The smoke, in any case, "adds one more piece to the puzzle" of finding a cause for the explosion, Flandro said.
Mizell said that NASA officials have had access to the photos and videotapes since the beginning of their investigation. They were waiting to determine their "significance" before releasing them, he said.
Copies of the photos were shared with members of the investigating commission, who arrived at the Kennedy Space Center Thursday morning for two days of meetings with NASA officials and their first tour of the site of the accident.
Commission members were silent as they rode a bus to NASA headquarters Thursday morning, past the shuttle assembly building and, out against the horizon, the launching pad from which the shuttle began its flight.
"I think the mood on the bus was a serious one, with an obvious if unspoken cognizance that we're here where it happened," commission spokesman Mark Weinberg said.
It was "hard not to remember that," he said, with photos of the astronauts staring down from the walls of the meeting room.
After arriving by private plane on the three-mile-long runway used by shuttles returning from space missions, the commission held a daylong series of closed meetings with NASA officials.
The commission members were walked through the hours and minutes that preceded the ignition order that sent Challenger rising from the pad, focusing on what information was available to NASA officials before the launching, Weinberg said.
NASA officials provided detailed information on the solid rocket boosters, the orbiter's main engines and weather conditions at the time of the launching, he said.
After the meetings, commission Chairman William P. Rogers said: "Today's meetings were detailed and thorough, and were of benefit to the commission. We are looking forward to our on-site inspections tomorrow and to continuing our detailed investigation."
The panel was scheduled today to tour the shuttle launching pad and assembly building and view the 12 tons of Challenger debris recovered from the ocean off Cape Canaveral.