Expedition 43 NASA Astronaut Scott Kelly walks along the Avenue of the Cosmonauts where two long rows of trees are all marked with the name and year of the crew member who planted them starting from Yuri Gagarin's tree, Friday, March 20, 2015 at the Cosmonaut Hotel in Baikonur, Kazakhstan. Kelly, and Russian Cosmonauts Gennady Padalka, and Mikhail Kornienko of the Russian Federal Space Agency (Roscosmos) are preparing for launch to the International Space Station in their Soyuz TMA-16M spacecraft from the Baikonur Cosmodrome in Kazakhstan March 28, Kazakh 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)

Expedition 43 Russian Cosmonauts Mikhail Kornienko, left, and Gennady Padalka of the Russian Federal Space Agency (Roscosmos), center, and NASA Astronaut Scott Kelly answer questions from the press while standing on the Avenue of the Cosmonauts where two long rows of trees are all marked with the name and year of the crew member who planted them starting from Yuri Gagarin's tree, Saturday, March 21, 2015 at the Cosmonaut Hotel in Baikonur, Kazakhstan. Kelly, Padalka, and Kornienko are preparing for launch to the International Space Station in their 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)

Expedition 43 Russian Cosmonauts Mikhail Kornienko, left, and Gennady Padalka of the Russian Federal Space Agency (Roscosmos), center, and NASA Astronaut Scott Kelly answer questions from the press while standing on the Avenue of the Cosmonauts where two long rows of trees are all marked with the name and year of the crew member who planted them starting from Yuri Gagarin's tree, Saturday, March 21, 2015 at the Cosmonaut Hotel in Baikonur, Kazakhstan. Kelly, Padalka, and Kornienko are preparing for launch to the International Space Station in their 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)

Expedition 43 prime crew members: NASA Astronaut Scott Kelly, and Russian Cosmonauts Gennady Padalka, and Mikhail Kornienko of the Russian Federal Space Agency (Roscosmos), and backup crew members Sergei Volkov, and Alexey Ovchinin and of Roscosmos, and NASA Astronaut Jeff Williams walk along the Avenue of the Cosmonauts where two long rows of trees are all marked with the name and year of the crew member who planted them starting from Yuri Gagarin's tree, Saturday, March 21, 2015, Baikonur, Kazakhstan. Expedition 43 NASA Astronaut Scott Kelly, and Russian Cosmonauts Gennady Padalka, and Mikhail Kornienko of the Russian Federal Space Agency (Roscosmos) are scheduled to launch 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)

Expedition 43 prime crew members: NASA Astronaut Scott Kelly, and Russian Cosmonauts Gennady Padalka, and Mikhail Kornienko of the Russian Federal Space Agency (Roscosmos), and backup crew members Sergei Volkov, and Alexey Ovchinin and of Roscosmos, and NASA Astronaut Jeff Williams walk along the Avenue of the Cosmonauts where two long rows of trees are all marked with the name and year of the crew member who planted them starting from Yuri Gagarin's tree, Saturday, March 21, 2015, Baikonur, Kazakhstan. Expedition 43 NASA Astronaut Scott Kelly, and Russian Cosmonauts Gennady Padalka, and Mikhail Kornienko of the Russian Federal Space Agency (Roscosmos) are scheduled to launch 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)