Jack Fischer exchanges as they prepared to fly to the launch site for final pre-launch preparations.

At the Gagarin Cosmonaut Training Center in Star City, Russia, Expedition 51 crewmember Jack Fischer of NASA (left) exchanges morning greetings with his backup, Randy Bresnik of NASA April 5 as they prepared to fly to the launch site at the Baikonur Cosmodrome in Kazakhstan for final pre-launch preparations. Fischer and Fyodor Yurchikhin of the Russian Federal Space Agency (Roscosmos) will launch April 20 on the Soyuz MS-04 spacecraft from Baikonur for a four and a half month mission on the International Space Station. Photo: NASA/Rob Navias