Toxic leak forces International Space Station astronauts to move

A PART of the International Space Station has been evacuated following reports of a toxic substance leak.

The bright sun greets the International Space Station in this Nov. 22 scene from the Russian section of the orbital outpost, photographed by one of the STS-129 crew members. Image credit: NASA..

THE six astronauts at the International Space Station are safe and are taking shelter in the Russian segment after an alarm went off on the US side of the orbiting outpost, NASA says.

The US space agency said on Wednesday it could not confirm that an ammonia leak was the cause, as the Russian space agency reported earlier.

“ISS flight controllers are not sure if the alarm was triggered by a pressure spike, a faulty sensor, or a problem in a computer relay box,” NASA said on Twitter.

“Crew is safe. No ammonia leak confirmed. Crew responded to coolant loop pressure increases.”

American astronauts also tweeted to saw they were doing fine.

Hey everybody, thanks for your concern. We're all safe & doing well in the Russian segment. Follow @Nasa for updates on @Space_Station today

— Sam Cristoforetti (@AstroSamantha) January 14, 2015

Later, NASA said indications were of a “false alarm”.

Russia’s space agency had blamed the evacuation on a leak of a toxic substance.

About 7:50 a.m. EST: A live #NASA TV update on the situation aboard #ISS. Watch http://t.co/6XtjOi1yJo

— NASA (@NASA) January 14, 2015

The “toxic substance was emitted from a cooling system into the station’s atmosphere” in the US segment of the station, the agency said in a statement.

“At present the American segment has been evacuated and the crew is safely located in the Russian segment,” the statement said.

The American segment has been sealed off.

Leak ... An inside look at the International Space Station. Picture: Supplied

A representative of the Russian mission control centre told Russian news agencies that the substance was ammonia.

The accident could also delay the departure of the US SpaceX cargo ship Dragon, which brought supplies earlier this week.

Fixing the leak may also require an emergency space walk, he added.

The #Exp42 crew members are safe inside the Russian segment of the #ISS following an alarm in the U.S. segment at about 4 a.m. EST.

— NASA (@NASA) January 14, 2015

#ISS flight controllers are not sure if the alarm was triggered by a pressure spike, a faulty sensor, or a problem in a computer relay box.

— NASA (@NASA) January 14, 2015

The International Space Station is a rare area of US-Russian co-operation that has not been hit by the crisis in Ukraine, which has prompted Washington to impose sanctions on Moscow.

In total 16 countries work on the ISS, whose cost is mainly shouldered by the United States.

Since NASA phased out the space shuttle system in 2011, it depends entirely on Russia to send its astronauts to the ISS.