Canadian astronaut Robert Thirsk is back from his long journey in space, and is now getting ready for a long journey to physical recovery.

Thirsk has lost muscle and bone mass from his six-month long stay at the International Space Station, and will spend six more months on earth in intense rehab to fully recover.

"I am in a phase right now called base data collection, and rehabilitation where I continue to be a laboratory rat," he said in Moscow Thursday.

He reunited with his wife and three kids in Moscow, and will soon return to Houston where they now live.

He will then schedule a trip to Canada where he will talk about his mission.

"I enjoyed my six months in space, it was the fulfillment of a dream, but I am an earthling," Thirsk told reporters from a news conference in Russia.

Thirsk and the rest of the crew completed 100 scientific experiments. He also worked as a repairman and robotics operator, but still had to fit in hours of exercise each day to prevent further bone and muscle loss because of the zero gravity conditions.

"Within two days (of returning to Earth) I'm 80 percent there I think, of being fairly normal. I know I am not normal, but I feel normal," he said.

Barely back on Earth, he is already musing about returning to the International Space Station.

"If I had the opportunity to fly again, yes!," Thirsk said.

He was not put off by the rocky ride he experienced during re-entry into the atmosphere on Tuesday while being strapped into a cramped space capsule.

"Imagine being stuffed into a Volkswagen Beetle, going for a ride on a roller-coaster, going to a laser light show and riding on the back of a bucking bronco," he said Wednesday in an interview on a flight to Moscow from Kazakhstan.

"Combine all these things together, multiply by 10 and that's what it's like to land."

Thirsk said gravity made it hard to stand up for the first time upon landing.

"I felt like I had 200 pounds on my shoulders and I was doing an exercise in a gym." he said.

"The dizziness is significant. It felt like someone was moving the floor on me all the time."

But he said he'd have to check with his boss, -- and his wife --about any future plans to go back to space.

Thirsk's mission marked a pair of firsts: not only was it the longest-ever space stay for a Canadian, but it also marked the first time two Canadians had ever crossed paths in space.

He actually accomplished the latter feat twice during his extended stay. Thirsk was visited by fellow astronaut Julie Payette in mid-July, while he received a visit in October from Canada's first space tourist, Cirque du Soleil founder Guy Laliberte.

Thirsk, a native of New Westminster, B.C., returned to Earth on Tuesday with Belgian astronaut Frank De Winne and Russian cosmonaut Roman Romanenko.

With files from CTV's Genevieve Beauchemin and The Canadian Press