Dangling strap to blame for scary space leak?

James Oberg NBC News space analyst

Russian space officials are unofficially blaming the alarming pressure drop during last month's landing of the Soyuz TMA-6 spacecraft on a dangling strap and crew error, MSNBC.com has learned. The Russian space agency's draft report on the matter remains unsigned, however, according to the NASA safety official who provided MSNBC.com with a copy of the report.

The NASA official, who asked his name not be revealed, said that "disagreements between the specialists and crew" still had to be resolved, but that the Russians had shared the draft report in an e-mail to their NASA counterparts.

The pressure drop during the Oct. 11 landing is not a secret — both Soyuz commander Sergey Krikalev and passenger Gregory Olsen have publicly made reference to the unusual event. But neither the U.S. or Russian space agencies have offered any comment. The third man aboard the Soyuz as it returned to Earth from the international space station, NASA astronaut John Phillips, has not referred to the matter, either.

While the incident was not life-threatening — all passengers aboard Soyuz spacecraft have worn pressure suits during such mission-critical phases since a similar failure killed three cosmonauts in 1971 — the secrecy around its cause has inflamed private speculation about a possible design flaw or possible flaws in decision-making. A similar Soyuz is currently docked to the space station and with the U.S. shuttles grounded, the Soyuz is the station's lifeline.

“We had certain problems with pressurization before undocking,” Krikalev stated during a post-flight news conference. He added that there had been additional problems with the craft’s airtightness during the descent: “In principle this was an anomalous situation of medium complexity,” he added. “In fact, it was a fairly serious situation.”

During the three-hour coast from undocking to actually firing the craft’s braking engine for the descent into the atmosphere, Soyuz cabin pressure fell from the normal 765 mmHG (equivalent to sea level) to below 660 mmHg (equivalent to air density in Taos, New Mexico), another source said shortly after the incident. The crew was instructed to pump the pressure back up by releasing bottled oxygen, and there was some improvement.

What may have happened
Two hatches must be sealed off before the Soyuz can leave the space station: one from the forward orbital module to the station, and one from the descent module — where the crew actually rides. It is the descent module that actually lands on Earth; the other parts of the spacecraft separate from it before landing.

A post-landing inspection of the descent module hatch found "an impression in the seal ... which resembled the buckle of a strap," according to the Russian draft report. Such straps are used to hold insulation blankets in place against the insides of the exterior walls of the spacecraft in order to prevent moisture condensation.

Normally, steps are taken to make sure there are no foreign objects trapped in the hatches when they are closed for departure. But this time, the report suggests, the crew was careless.

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