Expedition 52 flight engineers Sergey Ryazanskiy of Roscosmos, seated left, and Randy Bresnik of NASA 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. Photo Credit: (NASA/Bill Ingalls)

Expedition 52 flight engineers Sergey Ryazanskiy of Roscosmos, seated left, and Randy Bresnik of NASA 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. Photo Credit: (NASA/Bill Ingalls)

Expedition 52 flight engineers Sergey Ryazanskiy of Roscosmos, seated left, and Randy Bresnik of NASA 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. Photo Credit: (NASA/Bill Ingalls)

Expedition 52 flight engineer Paolo Nespoli of ESA signs 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. Photo Credit: (NASA/Bill Ingalls)

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, not pictured, 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. Photo Credit: (NASA/Bill Ingalls)

Expedition 52 backup crew members, Norishige Kanai, seated left, Alexander Misurkin, and Mark Vande Hei, seated right, sign a guest book at the "Memorial working study of Yuri Gagarin" at the Gagarin Cosmonaut Training Center (GCTC) as Expedition 52 flight engineers Paolo Nespoli of ESA, standing left, Sergey Ryazanskiy of Roscosmos, center, and Randy Bresnik of NASA, look on, 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. Photo Credit: (NASA/Bill Ingalls)

Expedition 65 backup crew member, Anton Shkaplerov of Roscosmos signs a guest book at the "Memorial working study of Yuri Gagarin" at the Gagarin Cosmonaut Training Center (GCTC), as his crew mates watch, Wednesday, March 24, 2021 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. Photo Credit: (NASA/GCTC/Irina Spector)

Expedition 64 backup crew member NASA astronaut Mark Vande Hei signs a guest book at the "Memorial working study of Yuri Gagarin" at the Gagarin Cosmonaut Training Center (GCTC), as his crew mates watch, Thursday, Sept. 24, 2020 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. Photo Credit: (NASA/GCTC/Andrey Shelepin)

Expedition 64 prime crew member NASA astronaut Kate Rubins signs a guest book at the "Memorial working study of Yuri Gagarin" at the Gagarin Cosmonaut Training Center (GCTC), as her crew mates watch, Thursday, Sept. 24, 2020 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. Photo Credit: (NASA/GCTC/Andrey Shelepin)

Expedition 65 prime crew member, Mark Vande Hei of NASA signs a guest book at the "Memorial working study of Yuri Gagarin" at the Gagarin Cosmonaut Training Center (GCTC), as his crew mates watch, Wednesday, March 24, 2021 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. Photo Credit: (NASA/GCTC/Irina Spector)

Expedition 65 backup crew member, Anne McClain of NASA signs a guest book at the "Memorial working study of Yuri Gagarin" at the Gagarin Cosmonaut Training Center (GCTC), as her crew mates watch, Wednesday, March 24, 2021 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. Photo Credit: (NASA/GCTC/Irina Spector)

Expedition 65 prime crew member, Pyotr Dubrov of Roscosmos signs a guest book at the "Memorial working study of Yuri Gagarin" at the Gagarin Cosmonaut Training Center (GCTC), as his crew mates watch, Wednesday, March 24, 2021 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. Photo Credit: (NASA/GCTC/Irina Spector)

Expedition 65 prime crew member, Oleg Novitskiy of Roscosmos signs a guest book at the "Memorial working study of Yuri Gagarin" at the Gagarin Cosmonaut Training Center (GCTC), as his crew mates watch, Wednesday, March 24, 2021 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. Photo Credit: (NASA/GCTC/Irina Spector)

Expedition 64 backup crew member Oleg Novitskiy of Roscosmos, signs a guest book at the "Memorial working study of Yuri Gagarin" at the Gagarin Cosmonaut Training Center (GCTC), as his crew mates watch, Thursday, Sept. 24, 2020 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. Photo Credit: (NASA/GCTC/Andrey Shelepin)

At the Gagarin Museum located at the Gagarin Cosmonaut Training Center in Star City, Russia, Expedition 38/39 Flight Engineer Rick Mastracchio of NASA studies a model of a Soyuz spacecraft during a tour October 22, 2013. Mastracchio, Flight Engineer Koichi Wakata of the Japan Aerospace Exploration Agency and Soyuz Commander Mikhail Tyurin will launch Nov. 7, Kazakh time from the Baikonur Cosmodrome in Kazakhstan on the Soyuz TMA-11M spacecraft for the start of a six-month mission on the International Space Station. NASA/Stephanie Stoll

At the Korolev Library in Moscow named after the Russian space designer, Sergei Korolev, NASA’s Expedition 59 astronauts Christina Koch (left) and Nick Hague (right) study a framed drawing of a Soyuz rocket Feb. 21 that Korolev himself drew decades ago. Koch, Hague and Alexey Ovchinin of Roscosmos will launch March 14, U.S. time, on the Soyuz MS-12 spacecraft from the Baikonur Cosmodrome in Kazakhstan for a six-and-a-half month mission on the International Space Station. Andrey Shelepin/Gagarin Cosmonaut Training Center

At the Gagarin Cosmonaut Training Center in Star City, Russia, Expedition 39/40 Soyuz Commander Alexander Skvortsov of Roscosmos studies a flight plan March 5 as he and his crewmates, NASA Flight Engineer Steve Swanson and Flight Engineer Oleg Artemyev of Roscosmos conducted final qualification exams. They are preparing for their launch to the International Space Station from the Baikonur Cosmodrome in Star City, Russia March 26, Kazakh time, on the Soyuz TMA-12M spacecraft for a six-month mission. NASA/Stephanie Stoll

3593: At the Gagarin Cosmonaut Training Center in Star City, Russia, Expedition 42/43 Soyuz Commander Anton Shkaplerov of the Russian Federal Space Agency (Roscosmos) studies systems manuals as he prepares to enter a Soyuz simulator October 31 for the second day of qualification exams. Shkaplerov, NASA Flight Engineer Terry Virts and European Space Agency Flight Engineer Samantha Cristoforetti are preparing for launch in the Soyuz TMA-15M spacecraft from the Baikonur Cosmodrome in Kazakhstan Nov. 24, Kazakh time, for a 5 ½ month mission on the International Space Station. NASA/Stephanie Stoll

At the Gagarin Cosmonaut Training Center in Star City, Russia, Expedition 34/35 Soyuz Commander Roman Romanenko studies a flight data file manual in front of a Soyuz spacecraft simulator Nov. 28, 2012 as he and his crewmates conducted the second of two days of flight qualification exams. Romanenko, NASA Flight Engineer Tom Marshburn and Flight Engineer Chris Hadfield of the Canadian Space Agency are scheduled to launch Dec. 19 from the Baikonur Cosmodrome in Kazakhstan on the Soyuz TMA-07M spacecraft, bound for a 5-month mission on the International Space Station. NASA/Stephanie Stoll

Expedition 43 NASA Astronaut Scott Kelly's girlfriend, Amiko Kauderer, and Kelly's twin brother, retired NASA Astronaut Mark Kelly, meet with Gagarin Cosmonaut Training Center (GCTC) Chief Epidemiologist Sergei Savin to be medically cleared to visit with Scott Thursday, March 26, 2015 at the Cosmonaut Hotel in Baikonur, Kazakhstan. Mark Kelly, who flew four space shuttle missions and commanded the final flight of space shuttle Endeavour, will participate in biomedical studies on the ground while his twin is on board the orbiting laboratory. Scott Kelly, Russian cosmonauts Gennady Padalka, and Mikhail Kornienko of the Russian Federal Space Agency (Roscosmos) launched to the International Space Station in the Soyuz TMA-16M spacecraft from the Baikonur Cosmodrome in Kazakhstan March 28, Kazakh time (March 27 Eastern time.) As the one-year crew, Kelly and Kornienko will return to Earth on Soyuz TMA-18M in March 2016. Photo Credit (NASA/Bill Ingalls)