The astronauts living onboard the International Space Station are safe after evacuating part of the station when they awoke to an alarm going off this morning.
NASA spokesman Kelly Humphries told Computerworld there was initial concern of a possible ammonia leak inside the station, but that has since been ruled out. It now appears there may be a faulty sensor in a computer relay box that sends commands and data to different onboard computer systems, he said.
When the alarm went off at 4 a.m. ET, the six astronauts evacuated the main part of the orbiting station and sealed themselves in the Russian segment of the orbiter.
They are still sheltering there even though NASA has determined there was no ammonia leak because many of the station's non-essential systems powered down after the alarm went off.
"They got their masks on and went into the Russian segment, and we isolated them and closed the hatch this morning," said Humphries from NASA's Johnson Space Center in Houston. "It all went as planned. It's one of the top risks we have on the space station because it's a toxic chemical ... We hope to have them out by the end of the day."
He added that it will take a while just to get the station's systems running normally again today.
"We want to make sure the crew is thoroughly safe before we open the hatches and let the crew back into the rest of the station again," Humphries said. "First you attend to the safety of the crew. Second, you attend to the safety of the space station."
Early this morning, flight controllers at mission control at the Johnson Space Center reported an increase in pressure in the water loop for the orbiter's thermal control system B. They then noted an increase in cabin pressure.
The worse case scenario would have been an ammonia leak, which led NASA engineers to sound the alarm.
Humphries said they are not positive the problem lies in the station's computer system but they will be spending the day investigating it.
"We're not sure yet but those are the legs we're tracking down," he said. "That's what we're thinking might have happened ... Now we're looking at the data to get a real understanding of what's happened."
NASA is expected to update the situation later today.