Astronauts aboard the space shuttle Discovery have got a case of stuffy heads, but NASA doesn't think they're sick.
More likely, the effects reported by the astronauts have more to do with crowd control and the pockets of carbon dioxide generated when they gather in groups, space station flight controller Heather Rarick said.
"I don't think they have any ill health whatsoever," Rarick told reporters in an early morning briefing.
Discovery commander Rick Sturckow radioed Mission Control early Wednesday to say his crew was complaining of stuffiness and that it was a new experience when compared to his three previous spaceflights.
He reported it because Mission Control should know, but stressed that the discomfort was relatively low and would have no impact "on our ability to function fully and complete the mission successfully."
Rarick said that the symptoms reported by the crew could be due to poor ventilation in certain spots between Discovery and the International Space Station.
A similar situation has happened before. In 1999, higher than expected carbon dioxide levels in the space station's Russian-built Zarya module were thought to have contributed to ill effects reported by astronauts who complained of headaches and nausea. The symptoms eased after the astronauts returned to their shuttle.
Rarick said carbon dioxide levels on the space station and Discovery should be within the normal range. But it is possible that pockets of carbon dioxide could develop as the astronauts work in close quarters with one another, she added.
There are 13 people — a record-tying crowd — currently living on the linked space station and Discovery - seven astronauts from the shuttle and six others on the station. Rarick said that Mission Control and the astronauts have been vigilant in their efforts to ensure good ventilation between the spacecraft.
Astronauts have been truly sick in space before, most recently last year when a European astronaut had to pass on a spacewalk due to a bad bout of space sickness. But Sturckow and his crew underwent NASA's regular quarantine procedures before launch to avoid developing an illness in space and are not medically ill, Rarick said.
The astronauts are also not affected to the point where their orbital work is suffering, she added. Sturckow and his crew are in the middle of a 13-day mission to deliver new science gear and supplies to the space station and have been on or ahead of their mission plan in terms of cargo transfer, mission managers said.
On Wednesday, the astronauts plan to move a pair of sophisticated racks of science equipment to study new materials and fluid physics in space aboard the station. They delivered a treadmill named after TV comedian Stephen Colbert on Tuesday.
"As long as they feel like they can continue to do their job, we probably won't spend much time working on that problem," Rarick said.