Canadian astronaut David Saint-Jacques was happy to be back on terra firma Friday as he emerged from a Soyuz capsule, took off his helmet and gas mask and wiped his face.

Actually, Saint-Jacques hadn't really been in space but had been using a simulator along with fellow astronauts Anne McClain and Oleg Kononenko at a training centre just outside Moscow.

The three were able to perform various manoeuvres to extricate themselves from an obviously fictitious but perilous situation.

"We managed to get back to Earth," Saint-Jacques, 48, said upon exiting the capsule. "We're not exactly certain where we are but we're surprised to see all you reporters at the landing."

Saint-Jacques, McClain and Kononenko will blast off aboard a Soyuz aircraft from Kazakhstan on Dec. 20 as it heads to the International Space Station for a six-month stay.

Over the next four months, the Canadian, the American and the Russian will be put through their paces with further simulated disaster scenarios.

"What we were practising today was a precipitate departure from the station in case of air contamination from ammoniac," said Saint-Jacques.

"Normally, we have to go in with protective masks and then eventually we have to secure our helmets."

Saint-Jacques said the manoeuvre was a flying success even after the instructors challenged them by disabling the engine and the central computer.

"Everybody says that after two years of training like this, that you're expecting it to happen like that in the Soyuz, so you're anxious when launch day comes," he said.

"Then nothing breaks — that's what we're hoping for."

The Quebec native, who will become the ninth Canadian to travel to space, will serve as a co-pilot for the Soyuz capsule and, because of his medical training, will be the crew's doctor on board the station during the stay.

An astronaut since 2009, Saint-Jacques was named to the mission in 2016.

He was trained as both an engineer and a doctor and will be the first Canadian aboard the space station since Chris Hadfield spent five months on it in 2012 and 2013.

Saint-Jacques will celebrate his 49th birthday on the station Jan. 6.

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