Image: Astronaut performing spacewalk at ISS
NASA via AFP - Getty Images
NASA astronaut Scott Parazynski wears the backpack-style Extravehicular Mobility Unit, or EMU, during an Oct. 28 spacewalk at the international space station. The space agency is looking into a potential problem with the EMU that was encountered during ground-based tests, and until the issue is resolved, future spacewalks are "no-go."
By NBC News space analyst
Special to MSNBC
updated 11/13/2007 12:20:49 PM ET 2007-11-13T17:20:49

HOUSTON - NASA’s already-tight schedule for assembly of the international space station is under new threat, this time because a trainee smelled smoke inside his spacesuit during a pressure-chamber test here on Earth.

Until the event can be explained, plans for two critical spacewalks at the space station are on hold. And without those spacewalks, NASA would have to delay next month's shuttle mission to deliver Europe's long-awaited Columbus space lab.

Such a delay could ripple down next year's tight launch schedule and complicate NASA's plans to finish construction of the space station by the end of 2010. Agency officials are hoping for a better outcome — that is, a quick resolution of the mystery that will preserve the current schedule.

Last Friday's incident was described in a brief item posted on a NASA Web site late Monday, at the tail end of a federal holiday. During a test of a spacesuit at NASA's Johnson Space Center in Houston, "a crew member reported the smell of smoke" coming from inside the suit's backpack-style life-support system, NASA said.

The test was immediately terminated and "the crew member extracted without incident," according to the status report.

NASA identified the crewman as Greg Chamitoff, an astronaut training for a long station expedition next year. In addition to the smell of smoke, Chamitoff also reported "heat behind his neck," some sources said. The sources spoke with msnbc.com on condition of anonymity because they weren't authorized to discuss the situation publicly.

Round-the-clock testing
An internal NASA memo reported that technicians went into the pressure chamber's air lock and retrieved the backpack unit, known as an Extravehicular Mobility Unit or EMU. Experts have been examining the unit around the clock to determine the cause of the smoky smell, the memo said.

Other NASA sources have reported privately that despite this testing over the Veterans Day weekend, no trace of any combustion or contamination could be found. This is both good news and bad news: good, because there appeared to be no potentially fatal fire; bad, because the incident still remains unexplained and the spacesuit design remains under suspicion.

Monday's report from NASA said that the agency has formed a mishap investigation board, and that its members recommended that all operations involving EMUs aboard the space station "be terminated until a root cause can be determined."

"Thus, the on-orbit EMUs are No Go," the item concluded.

The best-case resolution of this anomaly would be a quick determination that its cause is unrelated to the condition of the spacesuits now aboard the space station. In that case, the spacewalks could proceed as scheduled.

The worst-case scenario is much less likely but much more serious: This scenario would involve a previously unrecognized hardware problem with one or more of the station's suits that will need component replacement. That could take months to fix, delaying all future shuttle flights, unless a way is found to use the set of Russian spacesuits also on board the station.

Well-recognized hazard
Fire hazards in spacesuits, which utilize pure oxygen at high pressure, have been a well-recognized hazard for decades. In 1980, during testing of an unoccupied suit, contamination in one line led to a flash fire that caused the backpack to explode. Had this happened with an astronaut inside, the astronaut would have been killed.

Stricter standards of cleanliness have prevented any recurrence of that accident. But incidents where contamination was discovered in spacesuits aboard the space station have led to significant delays in planned spacewalks, until the hardware was cleaned or replaced.

Slideshow: Cool space views

During two spacewalks scheduled next week, NASA astronauts Peggy Whitson and Daniel Tani are due to reconnect data, power and coolant lines for the Harmony connecting module. Harmony was delivered to the space station during the recent shuttle mission and is to be installed in its final location by robotic arm this week. Once that is accomplished, the station crew has only 10 days to go through what would typically be a 15-day activation process, in order to get the new section is ready for installation of the Columbus module.

NASA memos indicate that spacewalk preparations are already behind schedule because of the spacesuit concerns. However, a status memo from spacesuit division chief Steve Doering, e-mailed Monday evening, was upbeat about the work done so far while remaining candid about what still remains to be done.

"A lot of good work was completed last night and today," he reported. "We are about 24 hours ahead of where we thought we’d be, but still have a lot of work to get through."

Doering said that the checks done so far indicated that all systems in the suspect backpack were "functioning properly," and that there was no sign of offgassing.

"The gas sample analyses and the gas filter analyses have been completed with no indication of the presence of combustion products," he continued. "This is not conclusive, but it is yet another indication that there was likely not a combustion event. We will have to wait until we get the all of the remaining sample results (water, swabs) back before we will have the full analysis story and can confirm."

The team is also hard at work on what he called "the facility portion of the investigation", he explained, "to determine if a combustion event upstream of the EMU could have been the source of the odor."

The path back to goodness
Doering said experts wanted to "determine the presence of combustion products in order to indicate or rule out the incident being the result of a combustion event. That will form the basis of our rationale to resume EMU O2 operations on-orbit or in the ground labs."

Adequate results should be available in a day or two, leading to a decision to clear the suits by Thursday, he said.

Tracking down the source of the smell itself was "a secondary objective behind resumption of operations," Doering said in the memo. He said experts planned to evaluate the condition of a carbon-dioxide scrubber inside the EMU to see if was the source of the odor.

None of the memos obtained by msnbc.com refer to the claims by other sources that the cosmonaut felt warmth on the back of his neck. That sensation could have been related to stress inside the suit under conditions of psychological and physiological stress, and conceivably not connected to a mechanical cause.

Until Friday, the spacesuit team at Johnson Space Center was relaxing after a strenuous effort to support a crucial Nov. 3 spacewalk to repair the station's solar panels. Some specialists were on leave and out of town. Doering’s memo expressed special gratitude to those who had to be called back over the weekend for yet another full court press.

An earlier version of this report misidentified the astronaut who reported smoke, based on incorrect information from sources.

James Oberg, space analyst for NBC News, spent 22 years at the Johnson Space Center as a Mission Control operator and an orbital designer.

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