Canadian astronaut Bob Thirsk holds willow sapling that are part of a Canadian experiment while on board the International Space Station. Thirsk says his six-month stay aboard the International Space Station has not been that stressful. (Canadian Space Agency/Canadian Press)

Bob Thirsk, the Canadian astronaut with the longest time in space, is eagerly anticipating seeing his family again and another of his favourite women — Mother Nature.

"I miss my family most of all of course, so that's No. 1 on the list," the father of three said Tuesday in his last news conference from the International Space Station.

"I'm already dreaming about those first hugs when I see my family in Moscow."

Thirsk, who is scheduled to land in Kazakhstan next Tuesday after six months in space, says there are several other things on Earth he dearly wants to experience again.

"I miss the wind, I miss the sunlight, I miss the smell of flowers and freshly cut grass," he said.

But Thirsk admits it hasn't been all that stressful spending such an extended period of time on the space station.

"I thought living in an isolated environment would be psychologically difficult," he said during a downlink with the Canadian Space Agency near Montreal.

"But I have special friends up here and it was not difficult at all."

Thirsk was joined on Tuesday by 11 fellow crew members who took turns answering questions from reporters around the world.

Thirsk has been living and working on the space station since May 29 after arriving on board a Russian Soyuz spacecraft.

It has been a busy six months with rarely a quiet moment on the giant space laboratory.

Three different U.S. space shuttles have ferried up fresh crews and visitors and several Russian cargo vessels have also brought up supplies.

Thirsk was visited by fellow Canadian astronaut Julie Payette in mid-July and by Canada's first space tourist, Guy Laliberte, in early October.

He says the most exciting moment of his mission was the arrival of an unpiloted, free-flying Japanese supply ship on Sept. 17.

The cargo vessel was captured by the Canadarm2 on the space station in what was described as "the first Canadian cosmic catch" for the robotic arm.

"We worked very hard on this, preparing for it for the last few years and this went off perfectly," he said.

Thirsk also started work on a Canadian experiment to study how gravity affects the formation of different kinds of wood.

The zero-gravity experiment involves 24 willow saplings which were brought up on the shuttle Atlantis.

Canadian Space Agency scientist Luchino Cohen says what's being studied is why willow trees keep standing even though their branches bend.

"The presence of this type of wood in trees is not really good for construction wood, whereas, on the contrary, it's good for pulp and paper because there's a lot of cellulose in there," he said in an interview.

"If we can learn how to control the production of this type of wood, that could help prepare trees which are a better fit for the construction industry."

The saplings will be returned to Earth in February for analysis by Prof. Rodney Savidge of the University of New Brunswick.