Astronauts of the first manned space mission since an unprecedented accident in October on Sunday brushed aside concerns about Russia's Soyuz rocket, saying risks were part of the job.
This will be the first launch of a manned spacecraft after the Soyuz-FG launch vehicle crash on October 11.
On Oct. 11, a rocket failure forced a Soyuz capsule carrying two astronauts to abort and make an emergency landing.
Russian Federation said last month, the October launch had failed because of a sensor that was damaged during assembly at the Baikonur cosmodrome but insisted the spacecraft remained reliable.
Less than two minutes into that flight, one of the rocket's four external boosters failed to separate and accidentally struck the core stage of the rocket, sending it spinning out of control.
NASA astronaut Anne McClain, David Saint-Jacques of the Canadian Space Agency and Oleg Kononenko of Russian space agency Roscosmos lifted off as scheduled at 6:31 a.m. EST. Meanwhile, Kononenko, Saint-Jacques and McClain will spend the next six and a half months in orbit.
After NASA retired the Space Shuttle in 2011, Russian Soyuz rockets have been the only way to get people to the International Space Station. "I'm grateful to Director General Dmitry Rogozin and the entire @NASA and @roscosmos teams for their dedication to making this launch a success", tweeted NASA Administrator Jim Bridenstine, shortly after liftoff.
"We are psychologically and technically prepared for blast-off and any situation which, God forbid, may occur on board".
Russian Federation said last month the October launch had failed because of a sensor damaged during assembly at the Baikonur cosmodrome, but insisted the spacecraft remained reliable.
Reports say a Russian Orthodox priest blessed their rocket before its flight on Monday, as per tradition.
Saint-Jacques will be his own main subject, using his medical training to try and develop new programs to keep astronauts healthy in space.
Kononenko is beginning his fourth mission to add to an impressive 533 days in space.
NASA's McClain was deployed to Iraq and has represented the United States women's national rugby union team.
She has said that training to spacewalk resembled the sport since it demands "grit, toughness, mental focus, and more".
The incident on 11 October cast a spotlight on the safety of Russia's space programme, whose fleet have suffered a number of technical failures in recent years.
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