Fischer and Yurchikhin join NASA's Peggy Whitson, Russia's Oleg Novitskiy and France's Thomas Pesquet at the station.
The other notable aspect of Thursday's launch is the size of the crew-two rather than three.
The launch is scheduled for 3:13 a.m. EDT, 1:13 p.m. Baikonur time.
Fischer and Yurchikhin were the first to receive permission from Roscosmos to name their Soyuz - "Argo". Another new investigation bound for the U.S. National Laboratory will look at using magnetized cells and tools to make it easier to handle cells and cultures, and improve the reproducibility of experiments. With a combined 537 days in orbit, he is one of the world's most experienced space fliers.
He later attended Air Force Test Pilot School at Edwards Air Force Base, Calif., and eventually helped put the F-22 Raptor through its paces. But all in all, it really is a fantastic little vehicle.
Fischer poses with his family behind a glass partition shortly before launch.
She will be called by President Donald Trump.
The duo was expected to reach the station in their Russian-designed Soyuz MS-04 spacecraft about six hours after the launch.
Fischer, a first-time space flier, and Yurchikhin, a veteran of four spaceflights, will spend more than 4 months aboard the orbiting laboratory before returning to Earth in early September.
Whitson, who on Monday (April 24) will surpass the record for the most time spent in space by an American astronaut - 534 days and counting, in the course of her three flights - recently had her own stay extended.
Novitskiy and Pesquet will return to Earth on June 2 and Yurchikhin will take over as commander of Expedition 52.
A rare two-man crew is scheduled to blastoff aboard the Soyuz MS-04 spaceship and travel to the International Space Station.