English: Expedition 52 flight engineers Paolo Nespoli of ESA, seated left, Sergey Ryazanskiy of Roscosmos, seated center, Randy Bresnik of NASA, seated right, joined by backup crew members, Norishige Kanai, standing left, Alexander Misurkin, and Mark Vande Hei, right, are seen as they sign a guest book at the "Memorial working study of Yuri Gagarin" at the Gagarin Cosmonaut Training Center (GCTC), Monday, July 10, 2017 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.