Updated

NASA engineers are tracking a potential, albeit minor, leak aboard the International Space Station (ISS), but do not consider it a concern for the orbital lab's astronaut crew or an upcoming shuttle launch, the agency said Wednesday.

An inspection of a vestibule bridging the station's new Harmony connecting module and NASA's Destiny laboratory indicated a slight air leak of about three pounds (1.3 kilograms) per day, NASA spokesperson Lynette Madison, of the agency's Johnson Space Center, told SPACE.com Wednesday.

But whether the leak is genuine or merely a phantom signal has yet to be determined.

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A close-up inspection of the vestibule seal by the station's three-astronaut Expedition 16 crew using an ultrasonic leak detector found no trace of a leak on Wednesday, Madison said.

Studies of the station's overall internal pressure also found no signs of decay, she added.

Engineers first recorded the potential leak during a "fine" check this week to ensure Harmony is properly connected to its Destiny docking port, Madison said.

A less sensitive, "gross" leak check performed earlier this month yielded no issues, she added.

"Nobody is really concerned about this," Madison said.

Engineers plan to check the seals between Harmony and its shuttle docking port for leaks on Thursday, and may recheck the module's connection to the Destiny lab later this week, she added.

Astronauts delivered the school bus-sized Harmony node to the ISS in late October during NASA's STS-120 shuttle flight.

The station's Expedition 16 crew outfitted the module with a shuttle docking port earlier this month and performed three spacewalks in 15 days to move the nearly 16-ton node to its final perch at the front of Destiny.

With its multiple berthing ports, Harmony is designed to serve as the anchor point for European and Japanese laboratories beginning with the European Space Agency's Columbus module set to launch next week.

NASA's shuttle Atlantis and seven astronauts are slated to launch toward the ISS on Dec. 6 to deliver Columbus and swap out one member of the station's Expedition 16 crew.

Top shuttle officials will meet Friday at NASA's Kennedy Space Center in Cape Canaveral, Fla., to set a firm launch date for the planned 11-day mission.

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