The Soyuz TMA-15M crew during a pre-flight news conference Saturday at the Baikonur Cosmodrome in Kazakhstan (left to right): NASA astronaut Terry Virts, Soyuz commander Anton Shkaplerov and European Space Agency flight engineer Samantha Cristoforetti. NASA TV

In clear but frigid weather, Russian engineers hauled a Soyuz rocket to the launch pad Friday, setting the stage for launch Sunday on a six-hour flight to ferry a veteran Russian cosmonaut, a NASA shuttle pilot and a European rookie to the International Space Station, boosting the lab's crew back to six and kicking off a busy winter of research and assembly work.

Soyuz TMA-15M commander Anton Shkaplerov, flanked by flight engineer Samantha Cristoforetti and NASA astronaut Terry Virts, are scheduled for liftoff from complex 31 at the Baikonur Cosmodrome in Kazakhstan at 4:01:14 p.m. EST (GMT-5; 3:01 a.m. Monday local time), roughly the moment Earth's rotation moves the pad into the plane of the station's orbit.

Soyuz flights are more commonly launched from pad 1, the same firing stand used by Yuri Gagarin at the dawn of the space age, but required maintenance prompted the Russians to use complex 31 for the TMA-15M launch, the first use of the facility for a piloted Soyuz flight since a station-bound crew took off from there in October 2012.

If all goes well, Shkaplerov and his crewmates will oversee an autonomous four-orbit rendezvous with the space station, moving in for docking at the Earth-facing Rassvet module Sunday around 9:53 p.m. Standing by to welcome them aboard will be Expedition 42 commander Barry "Butch" Wilmore, Alexander Samokutyaev and Elena Serova, who were launched to the outpost September 25.

Wilmore and company have had the station to themselves since Nov. 9 when Maxim Suraev, European Space Agency astronaut Alexander Gerst and NASA astronaut Reid Wiseman departed and returned to Earth. With the arrival of the TMA-15M crew, the focus of station operations will shift back to a full slate of research activity and a series of spacewalks next year to prepare the lab for dockings by new commercial crew ferry craft now under development in the United States.

Serova is the first female cosmonaut assigned to a long-duration flight aboard the station. A half-dozen female NASA astronauts have lived aboard the complex during the 14 years it has been staffed, but Cristoforetti is the first woman assigned to a long-duration flight by the European Space Agency.

A veteran fighter pilot and a captain in the Italian air force, Cristoforetti's resume reads like a roadmap to orbit, with a master's degree in mechanical engineering, expertise in aerospace propulsion technology, and more than 500 hours flying time in a variety of military aircraft, including the AM-X ground-attack fighter-bomber. During a pre-flight news conference, she described herself as "somebody who looks forward to a challenge."

"Learning how to be a flight engineer on the Soyuz was extremely gratifying," she said. "It kind of brought me back a little bit to flying a new airplane, where you have to learn, get familiar with all the systems, the procedures and what you do in a nominal case, what you do if something goes wrong. I've always been trained as a single-seat aircraft pilot so it was interesting to learn how to be a three-seater where you have a crew you have to work with. A very different mindset. Fun!"

Virts served as pilot of the shuttle Endeavour during a 2010 space station assembly mission. Like Cristoforetti, he is a veteran Air Force test pilot with 45 combat missions to his credit flying F-16 fighters. But in his case, moving from the shuttle to the Soyuz meant adapting to a smaller crew -- and a smaller, more nimble spacecraft.

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