MONTREAL -- Canadian astronaut Chris Hadfield may have become a worldwide Internet sensation with his dramatic photos, tweets and musical performances from space.

But it took some convincing by his two sons to persuade him of the importance of social media in the first place.

His conversion began several years ago -- long before Hadfield's mission to the International Space Station, which ended with great fanfare this week.

He initially balked when his sons began preaching the merits of Twitter and Facebook more than three years ago.

During a family Christmas get-together in 2009 his son Evan, who now lives in Germany, and Kyle, who's in China, pointed out that they relied on the Internet to find out what's going on.

They got on his case again when his five-month mission was announced in early September 2010. It was then that they decided to set up his two social-media sites.

A few months later, in January 2011, Hadfield only had about 1,000 followers on Twitter and about 600 Facebook friends -- a drop in the bucket compared to now.

During an interview back then, the three-time space visitor explained why he planned to make full use of social media during his space trip.

"It's an amazing human adventure," he told The Canadian Press. "The more people that can access it and look at parts of it that are interesting for them, the better."

He had only 20,000 Twitter followers when he blasted off with Russian space colleague Roman Romanenko and NASA astronaut Tom Marshburn on Dec. 19, 2012.

Upon his return to Earth this week, Hadfield was hovering around one million Twitter followers and more than 325,000 "Likes" on Facebook. His photography and music, distributed mainly through social media, eventually earned him mainstream news coverage around the world.

Hadfield is now back in Houston where he is to undergo debriefings and medical tests, and be reunited with his wife Helene.

The Canadian astronaut will hold his first news conference since his return on Thursday morning. It will be a video news conference, downlinked to the Canadian Space Agency near Montreal, and webcast live.

Prime Minister Stephen Harper has paid tribute to Hadfield's time aboard the space station. Speaking at an event Tuesday in Prince Edward Island, he said Hadfield had made all Canadians proud.

During the mission, Evan Hadfield acted as a self-described "Internet janitor" for his dad. The 28-year-old said recently that he read up to 13,000 online comments a day, from people writing about Hadfield.

"They're all very excited. They're saying they haven't paid attention to the space industry in their entire life, but now they really want to," the younger son said during an interview in March.

"They're so proud of him and of Canada."

Evan also played a big role in producing the now-famous "Space Oddity" video, the David Bowie cover; it was the most-watched video Tuesday on YouTube, with more than seven million views.

A Canadian Space Agency spokeswoman said in an email that the video was Hadfield's idea and was recorded "during his personal time."

She said the footage was recorded on weekends.

The video was produced by Hadfield's son. A former Bowie musician, fellow Sarnia, Ont., native Emm Gryner, helped put the project together.

Don't expect it to be sold in record stores anytime soon.

"As is the case of NASA, CSA releases footage upon request as long as it is not for commercial purposes," the CSA email said.

"A licensing agreement was signed with David Bowie's company and the CSA that allows this video to appear on You Tube for one year."