Earlier today, astronauts aboard the International Space Station (ISS) were evacuated from the US section of the orbiting satellite over fears of a suspected leak of toxic substances from the cooling system.

Although it was initially reported that the incident was caused by a discharge of ammonia into the station’s atmosphere, NASA officials have now said that it could be a false alarm caused by a sensor problem.

“Update: #Exp42 crew informed by controllers that it’s starting to look like a false indication, either a faulty sensor or computer relay,” NASA tweeted earlier.

As reported by BBC News, the Expedition 42 crew had only been awake for a couple of hours prior to the coolant pressure alarms sounding, and were busy unloading the cargo aboard SpaceX’s Dragon capsule which arrived at the ISS on Monday. These supplies, which included belated Christmas presents, groceries and science experiments, were urgently needed following the explosion of the Antares rocket last year, which destroyed the entire payload. According to the Russian space agency Roscosmos, the capsule will remain coupled to the ISS and will not make an emergency exit.

The agency also reportedly said that the situation is under control and emphasized that none of the crew had been in any danger. Still, no chances are being taken, so the six evacuated crew members will remain in the Russian sector until the situation is stabilized and the American sector has been sealed off.

According to NASA spokesperson Bob Jacobs, alarm bells rang when an increase in water loop pressure was observed, which was later followed by an increase in cabin pressure. Although this didn’t necessarily mean that there was an ammonia leak, they decided to prepare for a worst case scenario and isolated crew members from the affected area.

“We’re still trying to figure out exactly what happened,” NASA’s Jim Kelly told the crew. “We’re not entirely convinced that this is an ammonia leak.” If it does turn out to be a leak, however, an unscheduled spacewalk to repair any damage caused may be required.

According to RT, excluding the isolated area, the atmosphere is stable throughout the ISS and the level of air pollutants remains within acceptable levels. 

[Via BBC News, RT, ITAR-TASS and The Telegraph]