The first Canadian astronaut to command the International Space Station has been welcomed back to Earth as an internet superstar after he captivated people worldwide with his Twitter microblog.

Space station commander Chris Hadfield, who also became a music sensation when his zero-gravity version of David Bowie's Space Oddity went viral on the web, landed safely in Kazakhstan with NASA astronaut Tom Marshburn and Russian cosmonaut Roman Romanenko just after 11:30 GMT on Monday.

The astronauts were presented with Russian nesting dolls with their images painted on after their Soyuz space capsule descended under an orange parachute and raised clouds of dust as it ignited an engine to cushion its landing about 150 km south-east of the town of Zhezkazgan.

They wore traditional Kazakh embroidered robes and hats over their blue flight suits when they posed for cameras before returning to Russia's cosmonaut training centre outside Moscow for medical tests.

"It's part of humanity to be in space," Hadfield said in Russian.

"What we were feeling, what we were doing there, the music we played, this is a big part of our lives."

Seven million interested

He called his time in orbit during the five-month mission aboard the orbital outpost an amazing experience.

Hadfield made more history on Monday when he released the first music video shot in space - his poignant "cyberspace" rendition of Space Oddity, which was first released in 1969 just before the Apollo 11 moon landing.

The video, with its familiar refrain "Ground Control to Major Tom," had almost seven million hits on YouTube on Tuesday.

"I'm very happy that ... seven million are interested," Hadfield said. "It is very interesting and historic to be in space." 

The trio's mission was the 35th expedition aboard the space station, a permanently staffed, $100bn laboratory for biomedical, materials science, technology demonstrations and other research.

Replacements due

The mission included an impromptu spacewalk on Saturday to fix an ammonia coolant leak that had cropped up two days earlier.

Without the repair, NASA likely would have had to cut back the station's ongoing science experiments to save power.

The cooling system dissipates heat from electronics on the station's solar-powered wing panels.

During a 5 1/2-hour spacewalk, Marshburn and crewmate Chris Cassidy, who remains aboard the station, replaced a suspect ammonia coolant pump, apparently resolving the leak.

Engineers will continue to monitor the system for several weeks to make sure there are no additional problems.

Their replacements are due to launch from the Baikonur Cosmodrome in Kazakhstan on May 28.

Until then, a skeleton crew commanded by Pavel Vinogradov and including Cassidy and cosmonaut Alexander Misurkin will keep the station operating.

The crew's return to Earth comes on the 40th anniversary of the launch of the first US space station, Skylab. Three crews lived and worked on the relatively short-lived Skylab from May 1973 to February 1974.

The project helped NASA prepare for in-flight research aboard the space shuttles and the International Space Station, built in orbit beginning in 1998.

The outpost, which is scheduled to remain in orbit until at least 2020, has been permanently staffed since November 2000.

Source: Al Jazeera and agencies