He now feels like an old man, his arteries stiffer, his bones more porous and his body so weak he's forced to sit down when he showers.
After nearly five months in orbit, Chris Hadfield is re-adapting to gravity, getting used to the weight of his tongue in his mouth, being poked and prodded in a series of medical tests, having his blood drawn and his body taped with sensors.
In his first press conference since the end of his mission as commander aboard the International Space Station, the Canadian astronaut said that the global fame he has gained through social media remained an abstract concept for him and that he was still trying to readjust to life back on Earth, "tottering around like an old man."
"It's very confusing for my body now. My body was quite happy in space without gravity," Mr. Hadfield said in a news conference broadcast from Johnson Space Center in Houston.
By early July, Mr. Hadfield is expected to visit Canada, where he will appear at the Canada Day celebrations in Ottawa and as parade marshal at the Calgary Stampede.
His outreach efforts while in space, sharing photos and videos and famously singing a cover of David Bowie's Space Oddity had made him the most celebrated space traveller in decades. Media questions at the press conference came from as far away as Ireland and Mexico.
Mr. Hadfield said his aim, at the start of the mission, wasn't just completing the technical and scientific objectives but also sharing his experience, inspiring young people and making Canadians aware of their own space program.
"Yes, I am famous. It wasn't the aim… I hope I can have a regular life."
He said he had no concerns that, like past famous astronauts like Buzz Aldrin, he would struggle to adjust to a more mundane post-mission life. He has been an astronaut for two decades already and "I am not a person who looks backward and wishes that the past was my present."
Mr. Hadfield came back to Earth to a Canadian Space Agency facing budgetary constraints but he said uncertainty had always been a feature of space travel.
Noting that more than 130 scientific experiments were conducted aboard the orbital outpost during his mission, he said "it takes day-to-day work to earn the money of Canadian taxpayers."
He chuckled when a reporter asked if, like past Canadian astronauts Marc Garneau and Steve MacLean, he would want to head the CSA. For now, he said, "I'm trying to learn to walk again."
He said that he and his crewmate, NASA astronaut Tom Marshburn, have been joking that they look like "old duffers" as they shuffled around unsteadily.
His body is not used to supporting his head so his neck and back are sore. Under his clothes, he now wears a G-suit, with inflated trousers that squeeze his legs to help sustain blood pressure in his upper body.
Raffi Kuyumjian, CSA's Chief Medical Officer and Hadfield's Flight Surgeon, told reporters that Mr. Hadfield lost one per cent of bone density every month he was in orbit.
"Scientists are using Chris as a subject for their science experiments in order to collect data to better understand these effects and how to treat them, which will be important for our aging population," Dr. Kuyumjian said.
It will take three weeks before Mr. Hadfield can drive by himself again but he is already showing "noticeable improvement in his walk and equilibrium," Dr. Kuyumjian added in a statement released in the afternoon.
The journey home after 146 days in space, 144 of them in the space station, began when their Soyuz capsule slammed on its side in Kazakh steppes Tuesday evening.
What struck them right away when the hatched opened, he recalled, was the smell of the steppe's grass.
Afterward, there was 24-hour flight back to Houston, with stopovers in Scotland and Maine. There was the joy of the first shower in since December.
Mr. Hadfield, who garnered nearly a million followers on Twitter by showing stunning photos from space, was now like other Earthlings, sharing a pictures of his meal, his first since his return, a sandwich with some raw vegetables and fruit.
He also noted that, back at Johnson Space Center, he had to have 14 vials of blood samples drawn from him and he had to take co-ordination tests.
Astronauts returning to a full-gravity environment experience orthostatic hypotension, a low-blood pressure conditions that leads to dizziness and even fainting. So he was strapped to a tilt table to measure the changes in his blood pressure as he was shifted from lying flat to an upright position.
Mr. Hadfield shared those details because, he said, he would be sharing his space experience with others "for the rest of my life."