View of the Soyuz TMA-16M spacecraft as it departs the ISS on its return to Earth. Image was released by astronaut on social media.

ISS043E059259 (03/28/2015) --- NASA astronaut Scott Kelly (left) is happy to be aboard the International Space Station after the hatch opening of the Soyuz spacecraft Mar. 28, 2015. Kelly traveled with Expedition 43 Russian cosmonauts Mikhail Kornienko and Gennady Padalka of the Russian Federal Space Agency (Roscosmos) on the Soyuz TMA-16M that launched Friday, March 27, 2015 from Baikonur, Kazakhstan. Kelly and Kornienko will spend a year in space and return to Earth on Soyuz TMA-18M in March 2016. Most expeditions to the space station last four to six months. By doubling the length of this mission, researchers hope to better understand how the human body reacts and adapts to long-duration spaceflight. This knowledge is critical as NASA looks toward human journeys deeper into the solar system, including to and from Mars.

Workers review documents after the Soyuz TMA-16M spacecraft is lowered into position for encapsulation with its fairing, Friday, March 20, 2015 at the Baikonur Cosmodrome in 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. As the one-year crew, Kelly and Kornienko will return to Earth on Soyuz TMA-18M in March 2016. Photo Credit: (NASA/Bill Ingalls)

The Soyuz TMA-16M spacecraft is seen after being lowered into position for encapsulation with its fairing, Friday, March 20, 2015 at the Baikonur Cosmodrome in 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. As the one-year crew, Kelly and Kornienko will return to Earth on Soyuz TMA-18M in March 2016. Photo Credit: (NASA/Bill Ingalls)

Workers prepare to encapsulate the Soyuz TMA-16M spacecraft in its fairing, Friday, March 20, 2015 at the Baikonur Cosmodrome in 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. As the one-year crew, Kelly and Kornienko will return to Earth on Soyuz TMA-18M in March 2016. Photo Credit: (NASA/Bill Ingalls)

The Soyuz TMA-16M spacecraft is seen after being lowered into position for encapsulation with its fairing, Friday, March 20, 2015 at the Baikonur Cosmodrome in 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. As the one-year crew, Kelly and Kornienko will return to Earth on Soyuz TMA-18M in March 2016. Photo Credit: (NASA/Bill Ingalls)

Workers clean the Soyuz TMA-16M spacecraft after it is lowered into position for encapsulation with its fairing, Friday, March 20, 2015 at the Baikonur Cosmodrome in 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. As the one-year crew, Kelly and Kornienko will return to Earth on Soyuz TMA-18M in March 2016. Photo Credit: (NASA/Bill Ingalls)

Progress Space Rocket Center Spacecraft Machine Fitter Alexander Azihanov stops to pose for a portrait after the Soyuz TMA-16M spacecraft is lowered into position for encapsulation with its fairing, Friday, March 20, 2015 at the Baikonur Cosmodrome in 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. As the one-year crew, Kelly and Kornienko will return to Earth on Soyuz TMA-18M in March 2016. Photo Credit: (NASA/Bill Ingalls)

Progress Space Rocket Center Spacecraft Machine Fitter Alexander Azihanov stops to pose for a portrait after the Soyuz TMA-16M spacecraft is lowered into position for encapsulation with its fairing, Friday, March 20, 2015 at the Baikonur Cosmodrome in 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. As the one-year crew, Kelly and Kornienko will return to Earth on Soyuz TMA-18M in March 2016. Photo Credit: (NASA/Bill Ingalls)

The Soyuz TMA-16M spacecraft is seen after is was rolled out by train to the launch pad at the Baikonur Cosmodrome, Kazakhstan, Wednesday, March 25, 2015. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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/Victor Zelentsov)

The Soyuz TMA-16M spacecraft is seen after is was rolled out by train to the launch pad at the Baikonur Cosmodrome, Kazakhstan, Wednesday, March 25, 2015. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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/Victor Zelentsov)

The Soyuz TMA-16M spacecraft is seen after is was rolled out by train to the launch pad at the Baikonur Cosmodrome, Kazakhstan, Wednesday, March 25, 2015. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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/Victor Zelentsov)

The Soyuz TMA-16M spacecraft is rolled out by train to the launch pad at the Baikonur Cosmodrome, Kazakhstan, Wednesday, March 25, 2015. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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)

A security helicopter is seen surveying the launch pad area ahead of the Soyuz TMA-16M spacecraft arrival by train, Wednesday, March 25, 2015, Baikonur Cosmodrome, Kazakhstan. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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)

A Security team walks the railroad tracks ahead of the Soyuz TMA-16M spacecraft as it is rolled out by train to the launch pad at the Baikonur Cosmodrome, Kazakhstan, Wednesday, March 25, 2015. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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)

Security personnel are seen as the Soyuz TMA-16M spacecraft is rolled out by train to the launch pad at the Baikonur Cosmodrome, Kazakhstan, Wednesday, March 25, 2015. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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)

The Soyuz TMA-16M spacecraft is rolled out by train to the launch pad at the Baikonur Cosmodrome, Kazakhstan, Wednesday, March 25, 2015. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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)

The Soyuz TMA-16M spacecraft is seen after is was rolled out by train to the launch pad at the Baikonur Cosmodrome, Kazakhstan, Wednesday, March 25, 2015. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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/Victor Zelentsov)

The Soyuz TMA-16M spacecraft is seen after is was rolled out by train to the launch pad at the Baikonur Cosmodrome, Kazakhstan, Wednesday, March 25, 2015. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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/Victor Zelentsov)

Media photograph the Soyuz TMA-16M spacecraft as it launches to the International Space Station with Expedition 43 NASA Astronaut Scott Kelly, Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka of the Russian Federal Space Agency (Roscosmos) onboard Saturday, March 28, 2015, Kazakh time (March 27 Eastern time) from the Baikonur Cosmodrome in Kazakhstan. As the one-year crew, Kelly and Kornienko will return to Earth on Soyuz TMA-18M in March 2016. Photo Credit (NASA/Bill Ingalls)

The Soyuz TMA-16M spacecraft is seen as it launches to the International Space Station with Expedition 43 NASA Astronaut Scott Kelly, Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka of the Russian Federal Space Agency (Roscosmos) onboard Saturday, March 28, 2015, Kazakh time (March 27 Eastern time) from the Baikonur Cosmodrome in Kazakhstan. As the one-year crew, Kelly and Kornienko will return to Earth on Soyuz TMA-18M in March 2016. Photo Credit (NASA/Bill Ingalls)

The Soyuz TMA-16M spacecraft is seen in this long exposure photograph as it launches to the International Space Station with Expedition 43 NASA Astronaut Scott Kelly, Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka of the Russian Federal Space Agency (Roscosmos) onboard Saturday, March 28, 2015, Kazakh time (March 27 Eastern time) from the Baikonur Cosmodrome in Kazakhstan. As the one-year crew, Kelly and Kornienko will return to Earth on Soyuz TMA-18M in March 2016. Photo Credit (NASA/Bill Ingalls)

The Soyuz TMA-16M spacecraft is seen as it launches to the International Space Station with Expedition 43 NASA Astronaut Scott Kelly, Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka of the Russian Federal Space Agency (Roscosmos) onboard Saturday, March 28, 2015, Kazakh time (March 27 Eastern time) from the Baikonur Cosmodrome in Kazakhstan. As the one-year crew, Kelly and Kornienko will return to Earth on Soyuz TMA-18M in March 2016. Photo Credit (NASA/Bill Ingalls)

The Soyuz TMA-16M spacecraft is seen as it launches to the International Space Station with Expedition 43 NASA Astronaut Scott Kelly, Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka of the Russian Federal Space Agency (Roscosmos) onboard Saturday, March 28, 2015, Kazakh time (March 27 Eastern time) from the Baikonur Cosmodrome in Kazakhstan. As the one-year crew, Kelly and Kornienko will return to Earth on Soyuz TMA-18M in March 2016. Photo Credit (NASA/Bill Ingalls)

The Soyuz TMA-16M spacecraft is seen as it launches to the International Space Station with Expedition 43 NASA Astronaut Scott Kelly, Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka of the Russian Federal Space Agency (Roscosmos) onboard Saturday, March 28, 2015, Kazakh time (March 27 Eastern time) from the Baikonur Cosmodrome in Kazakhstan. As the one-year crew, Kelly and Kornienko will return to Earth on Soyuz TMA-18M in March 2016. Photo Credit (NASA/Bill Ingalls)

The Soyuz TMA-16M spacecraft is seen as it launches to the International Space Station with Expedition 43 NASA Astronaut Scott Kelly, Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka of the Russian Federal Space Agency (Roscosmos) onboard Saturday, March 28, 2015, Kazakh time (March 27 Eastern time) from the Baikonur Cosmodrome in Kazakhstan. As the one-year crew, Kelly and Kornienko will return to Earth on Soyuz TMA-18M in March 2016. Photo Credit (NASA/Bill Ingalls)

Flames from the Soyuz TMA-16M spacecraft are seen as it launches to the International Space Station with Expedition 43 NASA Astronaut Scott Kelly, Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka of the Russian Federal Space Agency (Roscosmos) onboard Saturday, March 28, 2015, Kazakh time (March 27 Eastern time) from the Baikonur Cosmodrome in Kazakhstan. As the one-year crew, Kelly and Kornienko will return to Earth on Soyuz TMA-18M in March 2016. Photo Credit (NASA/Bill Ingalls)

The Soyuz rocket and Soyuz TMA-16M spacecraft are assembled at Building 112 on the Baikonur Cosmodrome on Tuesday, March 24, 2015 in Baikonur, Kazakhstan. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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/Victor Zelentsov)

The Soyuz rocket and Soyuz TMA-16M spacecraft are assembled at Building 112 on the Baikonur Cosmodrome on Tuesday, March 24, 2015 in Baikonur, Kazakhstan. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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/Victor Zelentsov)

The Soyuz rocket and Soyuz TMA-16M spacecraft are assembled at Building 112 on the Baikonur Cosmodrome on Tuesday, March 24, 2015 in Baikonur, Kazakhstan. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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/Victor Zelentsov)

The Soyuz rocket and Soyuz TMA-16M spacecraft are assembled at Building 112 on the Baikonur Cosmodrome on Tuesday, March 24, 2015 in Baikonur, Kazakhstan. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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/Victor Zelentsov)

The Soyuz fairing is seen laying horizontal in front the of the Soyuz TMA-16M spacecraft as Expedition 43 Russian Cosmonauts Mikhail Kornienko, and, Gennady Padalka of the Russian Federal Space Agency (Roscosmos), and, NASA Astronaut Scott Kelly perform their fit checks, Sunday, March 15, 2015 at the Baikonur Cosmodrome in Kazakhstan. The trio 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/Victor Zelentsov)

The Soyuz rocket and Soyuz TMA-16M spacecraft are assembled at Building 112 on the Baikonur Cosmodrome on Tuesday, March 24, 2015 in Baikonur, Kazakhstan. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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/Victor Zelentsov)

The Soyuz rocket and Soyuz TMA-16M spacecraft are assembled at Building 112 on the Baikonur Cosmodrome on Tuesday, March 24, 2015 in Baikonur, Kazakhstan. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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/Victor Zelentsov)

The Soyuz rocket and Soyuz TMA-16M spacecraft are assembled at Building 112 on the Baikonur Cosmodrome on Tuesday, March 24, 2015 in Baikonur, Kazakhstan. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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/Victor Zelentsov)

The Soyuz rocket and Soyuz TMA-16M spacecraft are assembled at Building 112 on the Baikonur Cosmodrome on Tuesday, March 24, 2015 in Baikonur, Kazakhstan. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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/Victor Zelentsov)

The Soyuz rocket and Soyuz TMA-16M spacecraft are assembled at Building 112 on the Baikonur Cosmodrome on Tuesday, March 24, 2015 in Baikonur, Kazakhstan. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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/Victor Zelentsov)

The Soyuz rocket and Soyuz TMA-16M spacecraft are assembled at Building 112 on the Baikonur Cosmodrome on Tuesday, March 24, 2015 in Baikonur, Kazakhstan. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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/Victor Zelentsov)

The Soyuz rocket and Soyuz TMA-16M spacecraft are assembled at Building 112 on the Baikonur Cosmodrome on Tuesday, March 24, 2015 in Baikonur, Kazakhstan. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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/Victor Zelentsov)

The Soyuz rocket and Soyuz TMA-16M spacecraft are assembled at Building 112 on the Baikonur Cosmodrome on Tuesday, March 24, 2015 in Baikonur, Kazakhstan. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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/Victor Zelentsov)

The Soyuz rocket and Soyuz TMA-16M spacecraft are assembled at Building 112 on the Baikonur Cosmodrome on Tuesday, March 24, 2015 in Baikonur, Kazakhstan. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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/Victor Zelentsov)

The Soyuz rocket and Soyuz TMA-16M spacecraft are assembled at Building 112 on the Baikonur Cosmodrome on Tuesday, March 24, 2015 in Baikonur, Kazakhstan. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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/Victor Zelentsov)

The Soyuz rocket and Soyuz TMA-16M spacecraft are assembled at Building 112 on the Baikonur Cosmodrome on Tuesday, March 24, 2015 in Baikonur, Kazakhstan. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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/Victor Zelentsov)

The Soyuz rocket and Soyuz TMA-16M spacecraft are assembled at Building 112 on the Baikonur Cosmodrome on Tuesday, March 24, 2015 in Baikonur, Kazakhstan. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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/Victor Zelentsov)

The Soyuz rocket and Soyuz TMA-16M spacecraft are assembled at Building 112 on the Baikonur Cosmodrome on Tuesday, March 24, 2015 in Baikonur, Kazakhstan. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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/Victor Zelentsov)

The Soyuz rocket and Soyuz TMA-16M spacecraft are assembled at Building 112 on the Baikonur Cosmodrome on Tuesday, March 24, 2015 in Baikonur, Kazakhstan. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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/Victor Zelentsov)

The Soyuz rocket and Soyuz TMA-16M spacecraft are assembled at Building 112 on the Baikonur Cosmodrome on Tuesday, March 24, 2015 in Baikonur, Kazakhstan. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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/Victor Zelentsov)

The Soyuz rocket and Soyuz TMA-16M spacecraft are assembled at Building 112 on the Baikonur Cosmodrome on Tuesday, March 24, 2015 in Baikonur, Kazakhstan. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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/Victor Zelentsov)

The Soyuz rocket and Soyuz TMA-16M spacecraft are assembled at Building 112 on the Baikonur Cosmodrome on Tuesday, March 24, 2015 in Baikonur, Kazakhstan. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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/Victor Zelentsov)

The Soyuz rocket and Soyuz TMA-16M spacecraft are assembled at Building 112 on the Baikonur Cosmodrome on Tuesday, March 24, 2015 in Baikonur, Kazakhstan. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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/Victor Zelentsov)

The Soyuz rocket and Soyuz TMA-16M spacecraft are assembled at Building 112 on the Baikonur Cosmodrome on Tuesday, March 24, 2015 in Baikonur, Kazakhstan. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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/Victor Zelentsov)

Expedition 43 NASA Astronaut Scott Kelly inspects the Soyuz TMA-16M spacecraft during the final check of the spacecraft with Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka of the Russian Federal Space Agency (Roscosmos), Monday, March 23, 2015 at the Baikonur Cosmodrome in Kazakhstan. Kelly, Kornienko, and Padalka 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 NASA Astronaut Scott Kelly climbs the stairs to enter the Soyuz TMA-16M spacecraft during the final check of the spacecraft with Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka of the Russian Federal Space Agency (Roscosmos), Monday, March 23, 2015 at the Baikonur Cosmodrome in Kazakhstan. Kelly, Kornienko, and Padalka 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)

A Soyuz TMA-16M spacecraft access panel and inspection sticker is seen on the fairing during the final check of the spacecraft with Expedition 43 NASA Astronaut Scott Kelly, Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka of the Russian Federal Space Agency (Roscosmos) inside, Monday, March 23, 2015 at the Baikonur Cosmodrome in Kazakhstan. Kelly, Kornienko, and Padalka 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)

The Soyuz TMA-16M spacecraft and fairing are seen during the final check of the spacecraft with Expedition 43 NASA Astronaut Scott Kelly, Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka of the Russian Federal Space Agency (Roscosmos) inside, Monday, March 23, 2015 at the Baikonur Cosmodrome in Kazakhstan. Kelly, Kornienko, and Padalka 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 backup crew member Alexey Ovchinin of the Russian Federal Space Agency (Roscosmos) is seen inside the Soyuz TMA-16M spacecraft during a final check, Monday, March 23, 2015 at the Baikonur Cosmodrome in Kazakhstan. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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 NASA Astronaut Scott Kelly makes a photo of the Soyuz TMA-16M spacecraft during the final check of the spacecraft with Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka of the Russian Federal Space Agency (Roscosmos), Monday, March 23, 2015 at the Baikonur Cosmodrome in Kazakhstan. Kelly, Kornienko, and Padalka 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 NASA Astronaut Scott Kelly waits to climb the scaffolding to access the Soyuz TMA-16M spacecraft for his final check with fellow crew members Russian Cosmonauts Gennady Padalka, and Mikhail Kornienko of the Russian Federal Space Agency (Roscosmos), Monday, March 23, 2015 at the Baikonur Cosmodrome in Kazakhstan. Kelly, Kornienko, and Padalka 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)

The service structure arms are seen being lowered in this long exposure photograph less than an hour before the Soyuz TMA-16M spacecraft launched to the International Space Station with Expedition 43 NASA Astronaut Scott Kelly, Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka of the Russian Federal Space Agency (Roscosmos) onboard Saturday, March 28, 2015, Kazakh time (March 27 Eastern time) from the Baikonur Cosmodrome in Kazakhstan. As the one-year crew, Kelly and Kornienko will return to Earth on Soyuz TMA-18M in March 2016. Photo Credit (NASA/Bill Ingalls)

The Soyuz TMA-16M spacecraft is seen after having rolled out by train to the launch pad at the Baikonur Cosmodrome, Kazakhstan, Wednesday, March 25, 2015. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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 NASA Astronaut Scott Kelly is seen inside the Soyuz TMA-16M spacecraft during the fit check with Russian Cosmonauts Gennady Padalka and, Mikhail Kornienko of the Russian Federal Space Agency (Roscosmos), Sunday, March 15, 2015 at the Baikonur Cosmodrome in Kazakhstan. The trio 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/Victor Zelentsov)

Expedition 43 NASA Astronaut Scott Kelly is seen inside the Soyuz TMA-16M spacecraft during the fit check with Russian Cosmonauts Gennady Padalka and, Mikhail Kornienko of the Russian Federal Space Agency (Roscosmos), Sunday, March 15, 2015 at the Baikonur Cosmodrome in Kazakhstan. The trio 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/Victor Zelentsov)

The Soyuz TMA-16M spacecraft is rolled out by train to the launch pad at the Baikonur Cosmodrome, Kazakhstan, Wednesday, March 25, 2015. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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)

The Soyuz TMA-16M spacecraft is seen after is was rolled out by train to the launch pad at the Baikonur Cosmodrome, Kazakhstan, Wednesday, March 25, 2015. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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/Victor Zelentsov)

The Soyuz TMA-16M spacecraft is raised into the vertical position shortly after arriving at the launch pad, Wednesday, March 25, 2015, at the Baikonur Cosmodrome, Kazakhstan. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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 NASA Astronaut Scott Kelly, left, and Russian Cosmonauts Gennady Padalka, center, and Mikhail Kornienko of the Russian Federal Space Agency (Roscosmos) take a moment during their Soyuz TMA-16M spacecraft fit check to pose for a photograph, Sunday, March 15, 2015 at the Baikonur Cosmodrome in Kazakhstan. The trio 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/Victor Zelentsov)

Expedition 43 backup crew member Sergei Volkov of the Russian Federal Space Agency (Roscosmos) waits for his fellow backup crew members to exit the Soyuz TMA-16M spacecraft during a final check, Monday, March 23, 2015 at the Baikonur Cosmodrome in Kazakhstan. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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 NASA Astronaut Scott Kelly, left, Russian Cosmonauts Gennady Padalka, and Mikhail Kornienko of the Russian Federal Space Agency (Roscosmos), right adde seen during the Soyuz TMA-16M spacecraft final check, Monday, March 23, 2015 at the Baikonur Cosmodrome in Kazakhstan. Kelly, Kornienko, and Padalka 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 Russian Cosmonaut Mikhail Kornienko of the Russian Federal Space Agency (Roscosmos) climbs the stairs to enter the Soyuz TMA-16M spacecraft during the final check of the spacecraft with NASA Astronaut Scott Kelly, seated left, and Russian Cosmonaut Gennady Padalka, Monday, March 23, 2015 at the Baikonur Cosmodrome in Kazakhstan. Kelly, Kornienko, and Padalka 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 Russian Cosmonaut Gennady Padalka of the Russian Federal Space Agency (Roscosmos) climbs the stairs to enter the Soyuz TMA-16M spacecraft during the final check of the spacecraft with NASA Astronaut Scott Kelly, seated left, and Russian Cosmonaut Mikhail Kornienko, Monday, March 23, 2015 at the Baikonur Cosmodrome in Kazakhstan. Kelly, Kornienko, and Padalka 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 Russian Cosmonauts Mikhail Kornienko, left, and Gennady Padalka of the Russian Federal Space Agency (Roscosmos), and NASA Astronaut Scott Kelly, right, pose for a photograph on the stairs leading into the Soyuz TMA-16M spacecraft during the final check of the spacecraft, Monday, March 23, 2015 at the Baikonur Cosmodrome in Kazakhstan. Kelly, Kornienko, and Padalka 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 backup crew member NASA Astronaut Jeff Williams enters the Soyuz TMA-16M spacecraft during a final check, Monday, March 23, 2015 at the Baikonur Cosmodrome in Kazakhstan. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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 Russian Cosmonauts Mikhail Kornienko, left, and Gennady Padalka of the Russian Federal Space Agency (Roscosmos), and NASA Astronaut Scott Kelly, right, pose for a photograph on the stairs leading into the Soyuz TMA-16M spacecraft during the final check of the spacecraft, Monday, March 23, 2015 at the Baikonur Cosmodrome in Kazakhstan. Kelly, Kornienko, and Padalka 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 backup crew member Jeff Williams of NASA is seen inside the Soyuz TMA-16M spacecraft during the fit check with fellow backup crew members Russian Cosmonauts Alexey Ovchinin, and Sergei Volkov of Russia's Federal Space Agency (Roscosmos), Sunday, March 15, 2015 at the Baikonur Cosmodrome in Kazakhstan. The prime crew members Russian Cosmonauts Mikhail Kornienko, Gennady Padalka of the Russian Federal Space Agency (Roscosmos), and NASA Astronaut Scott Kelly 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/Victor Zelentsov)

Expedition 43 NASA Astronaut Scott Kelly, left, and Russian Cosmonauts Gennady Padalka, center, and Mikhail Kornienko of the Russian Federal Space Agency (Roscosmos) take a moment during their Soyuz TMA-16M spacecraft fit check to pose for a photograph, Sunday, March 15, 2015 at the Baikonur Cosmodrome in Kazakhstan. The trio 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/Victor Zelentsov)

Expedition 43 NASA Astronaut Scott Kelly, left, and Russian Cosmonauts Gennady Padalka, center, and Mikhail Kornienko of the Russian Federal Space Agency (Roscosmos) take a moment during their Soyuz TMA-16M spacecraft fit check to pose for a photograph, Sunday, March 15, 2015 at the Baikonur Cosmodrome in Kazakhstan. The trio 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/Victor Zelentsov)

Expedition 43 backup crew members Jeff Williams of NASA, left, Alexey Ovchinin, center, and Sergei Volkov of Russia's Federal Space Agency (Roscosmos) stop to wave hello to photographers during their Soyuz TMA-16M spacecraft fit check, Sunday, March 15, 2015 at the Baikonur Cosmodrome in Kazakhstan. The prime crew members Russian Cosmonauts Mikhail Kornienko, Gennady Padalka of the Russian Federal Space Agency (Roscosmos), and NASA Astronaut Scott Kelly 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/Victor Zelentsov)

Expedition 43 backup crew members Jeff Williams of NASA, left, Alexey Ovchinin, center, and Sergei Volkov of Russia's Federal Space Agency (Roscosmos) take a moment during their Soyuz TMA-16M spacecraft fit check to pose for a photograph, Sunday, March 15, 2015 at the Baikonur Cosmodrome in Kazakhstan. The prime crew members Russian Cosmonauts Mikhail Kornienko, Gennady Padalka of the Russian Federal Space Agency (Roscosmos), and NASA Astronaut Scott Kelly 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/Victor Zelentsov)

Expedition 43 NASA Astronaut Scott Kelly dons his Russian sokol suit during the Soyuz TMA-16M spacecraft fit check with Russian Cosmonauts Gennady Padalka and, Mikhail Kornienko of the Russian Federal Space Agency (Roscosmos), Sunday, March 15, 2015 at the Baikonur Cosmodrome in Kazakhstan. The trio 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/Victor Zelentsov)

A security van is seen surveying the launch pad area ahead of the Soyuz TMA-16M spacecraft arrival by train, Wednesday, March 25, 2015, Baikonur Cosmodrome, Kazakhstan. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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 NASA Astronaut Scott Kelly smiles during an Soyuz TMA-16M Trajectory and Flight Plan briefing, Thursday, March 19, 2015 at 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)

The Soyuz TMA-16M spacecraft is rolled out by train to the launch pad at the Baikonur Cosmodrome, Kazakhstan, Wednesday, March 25, 2015. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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 NASA Astronaut Scott Kelly prepares to have his Russian sokol suit pressure checked during the Soyuz TMA-16M spacecraft fit check with Russian Cosmonauts Gennady Padalka and, Mikhail Kornienko of the Russian Federal Space Agency (Roscosmos), Sunday, March 15, 2015 at the Baikonur Cosmodrome in Kazakhstan. The trio 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/Victor Zelentsov)

The Soyuz TMA-16M spacecraft is rolled out by train to the launch pad at the Baikonur Cosmodrome, Kazakhstan, Wednesday, March 25, 2015. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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)

The Soyuz TMA-16M spacecraft is rolled out by train to the launch pad at the Baikonur Cosmodrome, Kazakhstan, Wednesday, March 25, 2015. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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)

The Soyuz TMA-16M spacecraft is rolled out by train to the launch pad at the Baikonur Cosmodrome, Kazakhstan, Wednesday, March 25, 2015. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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 Russian Cosmonaut Gennady Padalka of the Russian Federal Space Agency (Roscosmos) talks with an instructor during an Soyuz TMA-16M Trajectory and Flight Plan briefing, Thursday, March 19, 2015 at Cosmonaut Hotel in Baikonur, Kazakhstan. Padalka, Russian Cosmonaut Mikhail Kornienko of Roscosmos and NASA Astronaut Scott Kelly 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)

The Soyuz TMA-16M spacecraft is seen after is was rolled out by train to the launch pad at the Baikonur Cosmodrome, Kazakhstan, Wednesday, March 25, 2015. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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 Russian Cosmonauts Mikhail Kornienko, left, Gennady Padalka of the Russian Federal Space Agency (Roscosmos), and, NASA Astronaut Scott Kelly take a moment during their Soyuz TMA-16M spacecraft fit check to pose for a photograph, Sunday, March 15, 2015 at the Baikonur Cosmodrome in Kazakhstan. The trio 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/Victor Zelentsov)

The Soyuz TMA-16M spacecraft is rolled out by train to the launch pad at the Baikonur Cosmodrome, Kazakhstan, Wednesday, March 25, 2015. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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 Russian Cosmonaut Gennady Padalka of the Russian Federal Space Agency (Roscosmos) talks with an instructor during an Soyuz TMA-16M Trajectory and Flight Plan briefing, Thursday, March 19, 2015 at Cosmonaut Hotel in Baikonur, Kazakhstan. Padalka, Russian Cosmonaut Mikhail Kornienko of Roscosmos and NASA Astronaut Scott Kelly 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)

A train backs up to building 112 to start to rollout the Soyuz TMA-16M spacecraft to the launch pad at the Baikonur Cosmodrome, Kazakhstan, Wednesday, March 25, 2015. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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 NASA Astronaut Scott Kelly dons his Russian sokol suit during the Soyuz TMA-16M spacecraft fit check with Russian Cosmonauts Gennady Padalka and, Mikhail Kornienko of the Russian Federal Space Agency (Roscosmos), Sunday, March 15, 2015 at the Baikonur Cosmodrome in Kazakhstan. The trio 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/Victor Zelentsov)

The Soyuz TMA-16M spacecraft is seen after having rolled out by train to the launch pad at the Baikonur Cosmodrome, Kazakhstan, Wednesday, March 25, 2015. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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)

The Soyuz TMA-16M spacecraft is rolled out by train to the launch pad at the Baikonur Cosmodrome, Kazakhstan, Wednesday, March 25, 2015. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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)

Technicians work to disengage the Soyuz TMA-16M spacecraft from the train that rolled it out to the launch pad at the Baikonur Cosmodrome, Kazakhstan, Wednesday, March 25, 2015. NASA Astronaut Scott Kelly, and Russian Cosmonauts Mikhail Kornienko, and Gennady Padalka 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 NASA Astronaut Scott Kelly, left, and Russian Cosmonaut Gennady Padalka of the Russian Federal Space Agency (Roscosmos) take turns testing a satellite phone during their Soyuz TMA-16M spacecraft fit check with fellow crew member Mikhail Kornienko of Roscosmos, Sunday, March 15, 2015 at the Baikonur Cosmodrome in Kazakhstan. The trio 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/Victor Zelentsov)

Expedition 43 NASA Astronaut Scott Kelly, left, and Russian Cosmonaut Gennady Padalka of the Russian Federal Space Agency (Roscosmos) are seen during an Soyuz TMA-16M Trajectory and Flight Plan briefing, Thursday, March 19, 2015 at Cosmonaut Hotel in Baikonur, Kazakhstan. Kelly, Padalka, and Russian Cosmonaut Mikhail Kornienko of 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 NASA Astronaut Scott Kelly dons his Russian sokol suit during the Soyuz TMA-16M spacecraft fit check with Russian Cosmonauts Gennady Padalka and, Mikhail Kornienko of the Russian Federal Space Agency (Roscosmos), Sunday, March 15, 2015 at the Baikonur Cosmodrome in Kazakhstan. The trio 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/Victor Zelentsov)

Expedition 43 Russian Cosmonauts Mikhail Kornienko, left, and Gennady Padalka, of the Russian Federal Space Agency (Roscosmos), and NASA Astronaut Scott Kelly answer reporters questions after having completed the Soyuz TMA-16M spacecraft final check, Monday, March 23, 2015 at the Baikonur Cosmodrome in Kazakhstan. Kelly, Kornienko, and Padalka 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)