Expedition 47 NASA astronaut Jeff Williams, seated left, Russian cosmonaut Alexei Ovchinin of Roscosmos, seated center, and Russian cosmonaut Oleg Skripochka sign a guest book at the "Memorial working study of Yuri Gagarin" at the Gagarin Cosmonaut Training Center (GCTC) as backup crew members: NASA astronaut Shane Kimbrough, standing left, Russian cosmonauts Sergei Ryzhikov, and Andrey Borisenko of Roscosmos look on, Friday, Feb. 26, 2016, in Star City, Russia. The memorial study represents Gagarin's working study in the way it was abandoned by Gagarin on March 27, 1968 before leaving for the airfield for training flight that became his last one.