
Retired NASA astronaut Scott Kelly poses a portrait, Monday, July 8, 2019 at NASA's Johnson Space Center in Houston, Texas. Photo Credit: (NASA/Bill Ingalls)

Former NASA astronaut Scott Kelly, left, gives video replies to questions from social media, Wednesday, May 25, 2016, in Washington. Photo Credit: (NASA/Bill Ingalls)

Former NASA astronaut Scott Kelly, left, gives video replies to questions from social media, Wednesday, May 25, 2016, in Washington. Photo Credit: (NASA/Bill Ingalls)

Former NASA astronaut Scott Kelly speaks during an event at the United States Capitol Visitor Center, Wednesday, May 25, 2016, in Washington. Photo Credit: (NASA/Bill Ingalls)

Former NASA astronaut Scott Kelly speaks during an event at the United States Capitol Visitor Center, Wednesday, May 25, 2016, in Washington. Photo Credit: (NASA/Bill Ingalls)

Former NASA astronaut Scott Kelly speaks during an event at the United States Capitol Visitor Center, Wednesday, May 25, 2016, in Washington. Photo Credit: (NASA/Bill Ingalls)

Former NASA astronaut Scott Kelly speaks during an event at the United States Capitol Visitor Center, Wednesday, May 25, 2016, in Washington. Photo Credit: (NASA/Bill Ingalls)

Former NASA astronaut Scott Kelly speaks during an event at the United States Capitol Visitor Center, Wednesday, May 25, 2016, in Washington. Photo Credit: (NASA/Bill Ingalls)

Former NASA astronaut Scott Kelly speaks during an event at the United States Capitol Visitor Center, Wednesday, May 25, 2016, in Washington. Photo Credit: (NASA/Bill Ingalls)

Former NASA astronaut Scott Kelly speaks during an event at the United States Capitol Visitor Center, Wednesday, May 25, 2016, in Washington. Photo Credit: (NASA/Bill Ingalls)

ISS046e025801 (01/27/2016) --- NASA astronaut Scott Kelly relocates spacewalk hardware and suits inside the Quest airlock on Jan. 27, 2016.

S99-05705 (May 1999) --- Astronaut Scott J. Kelly.

ISS044E000290 (06/14/2015) --- NASA astronaut Scott Kelly on the Internationa Space Station prepares another scientific experiment on June 16, 2015. Scott works with his fellow station crew members Russian cosmonauts Gennady Padalka, and Mikhail Kornienko.

Expedition 45/46 Commander, Astronaut Scott Kelly along with his brother, former Astronaut Mark Kelly speak to news media outlets about Scott Kelly's 1-year mission aboard the International Space Station. Photo Date: January 19, 2015. Location: Building 2. Photographer: Robert Markowitz

Expedition 45/46 Commander, Astronaut Scott Kelly along with his brother, former Astronaut Mark Kelly speak to news media outlets about Scott Kelly's 1-year mission aboard the International Space Station. Photo Date: January 19, 2015. Location: Building 2. Photographer: Robert Markowitz

Expedition 45/46 Commander, Astronaut Scott Kelly along with his brother, former Astronaut Mark Kelly speak to news media outlets about Scott Kelly's 1-year mission aboard the International Space Station. Photo Date: January 19, 2015. Location: Building 2. Photographer: Robert Markowitz

Expedition 45/46 Commander, Astronaut Scott Kelly along with his brother, former Astronaut Mark Kelly speak to news media outlets about Scott Kelly's 1-year mission aboard the International Space Station. Photo Date: January 19, 2015. Location: Building 2. Photographer: Robert Markowitz

S96-14778 (1996) --- Astronaut Scott Kelly.

ISS045E028258 (09/24/2015) --- NASA astronaut Scott Kelly gives himself a flu shot for an ongoing study on the human immune system. The vaccination is part of NASA’s Twins Study, a compilation of multiple investigations that take advantage of a unique opportunity to study identical twin astronauts Scott and Mark Kelly, while Scott spends a year aboard the International Space Station and Mark remains on Earth.

NASA Administrator Charles Bolden introduces former NASA astronaut Scott Kelly during an event at the United States Capitol Visitor Center, Wednesday, May 25, 2016, in Washington. Photo Credit: (NASA/Bill Ingalls)

NASA Administrator Charles Bolden introduces former NASA astronaut Scott Kelly during an event at the United States Capitol Visitor Center, Wednesday, May 25, 2016, in Washington. Photo Credit: (NASA/Bill Ingalls)

PHOTO DATE: 02-07-13 LOCATION: Ellington Field - Hangar 276 - Tarmac SUBJECT: Scott Kelly during T-38 flight prep and getting into aircraft along with Stephanie Wilson. PHOTOGRAPHER: BILL STAFFORD

ISS046e022896 (01/24/2016) --- NASA astronaut Scott Kelly took this image of Japan at night on Jan. 24, 2016. In his tweet Scott said: " GoodEvening #Japan! I look forward to meeting you again someday. #YearInSpace"

RETIRED NASA ASTRONAUT SCOTT KELLY, LEFT, AND PAYLOAD PLANNING MANAGER TONY PITTMAN PAUSE FOR A PHOTO BEFORE HANGING THE MISSION PATCH FOR EXPEDITION 46 ON THE WALL OF THE PAYLOAD OPERATIONS INTEGRATION CENTER

ISS043E182364 (05/08/2015) --- The Libyan city of Benghazi is shown in this image taken from the International Space Station by NASA astronaut Scott Kelly on May 8th, 2015.

ISS046e016803 (01/21/2016) --- NASA astronaut Scott Kelly tweeted this aurora image over Canada on Jan. 21, 2016 with the message: ""O Canada! Beneath thy shining skies. You were beautiful this morning! #YearInSpace”

ISS043E182407 (05/08/2015) --- Shades of beige dominate this image of the Libyan Desert and southwestern Egypt scene captured by NASA astronaut Scott Kelly aboard the international Space Station on May, 8th, 2015.

ISS046e015697 (01/20/2016) --- NASA astronaut Scott Kelly took this majestic image of the Earth at night highlighting the green and red hues of an Aurora. He tweeted this message along with the image: “The dance of #aurora. #YearInSpace"

ISS046e022766 (01/24/2016) --- NASA astronaut Scott Kelly captured this sunrise over Earth and tweeted this message: " blizzard2016 clearly seen off the #EastCoast as the sun begins to rise. Hope all OK! #BlizzardJonas #YearInSpace".

ISS043E182380 (05/08/2015) --- NASA astronaut Scott Kelly aboard the International Space Station captured this desert scene in northern Africa on May 8th, 2015. The area shown is the Calanscio Sand Sea, in northeastern Libya.

ISS043E194350 (05/15/2015) --- NASA astronaut Scott Kelly on the International Space Station tweeted this image out of an Earth observation image as part of his Space Geo trivia contest. Scott tweeted this comment and clue: "#SpaceGeo Four international borders in one photo from the International @Space_Station. Name them"! Two winners! Congrats to @TeacherWithTuba & @PC101!. The correct answer is :#SpaceGeo A: #Denmark #Norway #Sweden #Germany & #Poland. The winners will receive an autographed copy of this image when Scott returns to Earth in March 2016. Learn more about #SpaceGeo and play along every Wednesday for your chance to win: <a href="http://www.nasa.gov/feature/where-over-the-world-is-astronaut-scott-kelly/" rel="nofollow">www.nasa.gov/feature/where-over-the-world-is-astronaut-sc...</a>

JSC2010-E-124007 (August 2010) --- NASA astronaut Scott Kelly, Expedition 25 flight engineer and Expedition 26 commander, attired in a Russian Sokol launch and entry suit, takes a break from training in Star City, Russia to pose for a portrait. Photo credit: Gagarin Cosmonaut Training Center

Expedition 26 Commander Scott Kelly rest in a chair shortly after he and fellow crew members Alexander Kaleri and Oleg Skripochka landed in their Soyuz TMA-01M capsule near the town of Arkalyk, Kazakhstan on Wednesday, March 16, 2011. NASA Astronaut Kelly, Russian Cosmonauts Skripochka and Kaleri are returning from almost six months onboard the International Space Station where they served as members of the Expedition 25 and 26 crews. Photo Credit: (NASA/Bill Ingalls)

ISS044E045542 (08/10/2015) --- Good Morning From the International Space Station! NASA astronaut Scott Kelly took this photograph of a sunrise over the western United States and posted it to social media on Aug. 10, 2015. Kelly wrote, "#Good Morning to those in the western #USA. Looks like there's a lot going on down there. #YearInSpace"

ISS046e004535 (01/03/2016) --- Earth observation taken during a day pass by NASA astronaut Scott Kelly aboard the International Space Station. A Russian Soyuz spacecraft dominates the center of the view as it sits docked to the station. Kelly tweeted this image with the message: "Day 282. Soyuz silhouette and #sunset colors of our magnificent #Earth. #GoodNight from @space_station! #YearInSpace".

ISS045E082998 (10/28/2015) --- NASA astronaut Scott Kelly snaps a quick space selfie during his first ever spacewalk on Oct 28, 2015. Kelly and NASA astronaut Kjell Lindgren worked outside for seven hours and 16 minutes on a series of tasks to service and upgrade the International Space Station. They wrapped a dark matter detection experiment in a thermal blanket, lubricated the tip of the Canadarm2 robotic arm and then routed power and data cables for a future docking port.

ISS043E182401 (05/08/2015) --- A large portion of northern Africa is covered in desert sand as this image from the International Space Station by NASA astronaut Scott Kelly demonstrates. This nearly waterless area is located in the Great Sand Sea of the Libyan Desert and part of western Egypt.

ISS046e035715 (02/08/2016) --- NASA astronaut Scott Kelly acquired this image of Santa Clara, California on Feb. 8, 2016. He tweeted: "Got to see the #SuperBowl in person after all! But at 17,500MPH, it didn't last long. #YearInSpace

ISS043E241982 (05/23/2015) --- This Earth observation image of the Eastern coast of the United States from May 23, 2015 was tweeted out from the International Space Station by NASA astronaut Scott Kelly with the added comment: "To end #EMSWeek #JerseyCity where I worked as an EMT more than 30 years ago".

ISS043E182476 (05/08/2015) ---The US rugged southern Utah area is highlighted in this image captured by NASA astronaut Scott Kelly from the International Space Station May, 8th, 2015. The area shown is the Forbidden Canyon, Rainbow Plateau and San Juan River.

ISS045E002596 (09/14/2015) --- Expedition 45 commander Scott Kelly is seen peeking out of the space station’s Cupola module which provides a 360-degree view of the Earth below. The module is also used for robotics operations, including controlling the station’s main robotic device Canadarm2, seen below the Cupola.

ISS043182398 (05/08/2015) --- Another view of the northern African Great Sand Sea, Libyan Desert and western Egypt with orange parallel dunes taken on May 8th 2015 by NASA astronaut Scott Kelly on the International Space Station.

ISS043E182395 (05/08/2015) --- NASA astronaut Scott Kelly took this picture of the water filled Siwa Oasis in the northwestern Egyptian desert. Water is also treasured within the International Space Station where recycling plays an important role in conserving and reusing the precious life giving liquid.

ISS043E160084 (05/03/2015) --- NASA astronaut Scott Kelly enjoys his first drink from the new ISSpresso machine. The espresso device allows crews to make tea, coffee, broth, or other hot beverages they might enjoy.

ISS043E181459 (05/07/2015) – NASA astronauts Scott Kelly (left) and Terry Virts (right) work on a Carbon Dioxide Removal Assembly (CDRA) inside the station’s Japanese Experiment Module. The CDRA system works to remove carbon dioxide from the cabin air, allowing for an environmentally safe crew cabin.

ISS046e004756 (01/04/2016) --- NASA astronaut Scott Kelly captured this beige desert image as the International Space Station passed over Africa. He tweeted out this message: " I can always count on #Africa for colorful #EarthArt. #YearInSpace".

ISS046e009103 (01/16/2016) --- In orbit around the Earth on board the International Space Station NASA astronaut Scott Kelly captured this blue water image in his "Earth Art" series and tweeted it out with this message: " A splash of #EarthArt over the #Bahamas! #YearInSpace ".

ISS046e005831 (01/07/2016) --- Expedition 46 Commander and NASA astronaut Scott Kelly works to clean up a leak in the Waste and Hygiene Compartment aboard the International Space Station. Crew members are routinely called on for maintenance efforts across the orbiting laboratory as they work to keep their various life support systems in working order.

Retired NASA Astronaut Mark Kelly, left, fist pumps his identical twin brother, NASA Astronaut Scott Kelly through glass as Scott Kelly and fellow crew mates, Russian cosmonauts Gennady Padalka, and Mikhail Kornienko of the Russian Federal Space Agency (Roscosmos) participate in a press conference while in quarantine 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, Kornienko, and Padalka 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)

Expedition 26 Commander Scott Kelly wears a blue wrist band that has a peace symbol, a heart and the word "Gabby" to show his love of his sister-in-law U.S. Rep. Gabrielle Giffords as he rest onboard a Russian Search and Rescue helicopter shortly after he and fellow crew members Oleg Skripochka and Alexander Kaleri landed in their Soyuz TMA-01M capsule near the town of Arkalyk, Kazakhstan on Wednesday, March 16, 2011. NASA Astronaut Kelly, Russian Cosmonauts Skripochka and Kaleri are returning from almost six months onboard the International Space Station where they served as members of the Expedition 25 and 26 crews. Photo Credit: (NASA/Bill Ingalls)

Expedition 26 Commander Scott Kelly performs the traditional sighing of the helicopter that flew him from Arkalyk to Kustanay, Kazakhstan after he and Expedition 26 Flight Engineers Oleg Skripochka and Alexander Kaleri landed in their Soyuz TMA-01M capsule near the town of Arkalyk, Kazakhstan on Wednesday, March 16, 2011. NASA Astronaut Kelly, Russian Cosmonauts Skripochka and Kaleri are returning from almost six months onboard the International Space Station where they served as members of the Expedition 25 and 26 crews. Photo Credit: (NASA/Bill Ingalls)

Expedition 26 Commander Scott Kelly listens to reporters questions while wearing a traditional Kazakh hat at the Kustanay, Kazakhstan airport on Wednesday, March 16, 2011 after he and fellow crew members Alexander Kaleri and Oleg Skripochka landed in their Soyuz TMA-01M capsule near the town of Arkalyk, Kazakhstan. NASA Astronaut Kelly, Russian Cosmonauts Skripochka and Kaleri are returning from almost six months onboard the International Space Station where they served as members of the Expedition 25 and 26 crews. Photo Credit: (NASA/Bill Ingalls)

Expedition 26 Commander Scott Kelly looks out the window of a Russian Search and Rescue helicopter before the two hour helicopter ride to Kustanay, Kazakhstan shortly after he and fellow crew members Oleg Skripochka and Alexander Kaleri landed in their Soyuz TMA-01M capsule near the town of Arkalyk, Kazakhstan on Wednesday, March 16, 2011. NASA Astronaut Kelly, Russian Cosmonauts Skripochka and Kaleri are returning from almost six months onboard the International Space Station where they served as members of the Expedition 25 and 26 crews. Photo Credit: (NASA/Bill Ingalls)

Expedition 43 NASA Astronaut Scott Kelly answers questions from the press during media day, 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 NASA Astronaut Scott Kelly, left, and his identical twin brother Mark Kelly, pose for a photograph Thursday, March 26, 2015 at the Cosmonaut Hotel in Baikonur, Kazakhstan. 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 his identical twin brother Mark Kelly, pose for a photograph Thursday, March 26, 2015 at the Cosmonaut Hotel in Baikonur, Kazakhstan. 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 sits down for a television interview at the Cosmonaut Hotel, Thursday, March 19, 2015 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)

PHOTO DATE: 7-13-10 LOCATION:Bldg. 2N, Press Conf. Room SUBJECT: Expedition 25 press conference with NASA astronaut Scott Kelly and his crewmates, Russian cosmonauts Alexander Kaleri and Oleg Skripochka PHOTOGRAPHER: Lauren Harnett

PHOTO DATE: 7-13-10 LOCATION:Bldg. 2N, Press Conf. Room SUBJECT: Expedition 25 press conference with NASA astronaut Scott Kelly and his crewmates, Russian cosmonauts Alexander Kaleri and Oleg Skripochka PHOTOGRAPHER: Lauren Harnett

PHOTO DATE: 7-13-10 LOCATION:Bldg. 2N, Press Conf. Room SUBJECT: Expedition 25 press conference with NASA astronaut Scott Kelly and his crewmates, Russian cosmonauts Alexander Kaleri and Oleg Skripochka PHOTOGRAPHER: Lauren Harnett

ISS043E182745 (05/09/2015) --- NASA astronaut Scott Kelly and his crewmates on Expedition 43 capture Earth observation images as part of their duties on board the International Space Station and during their off time for interest and appreciation. This picture taken May 9th, 2015 of north eastern Brazil in South America showcases Sao Polo, and even displays the Guarulhos International Airport.

iss046e044605 (02/20/2016) --- Night falls for the Expedition 46 crew of the International Space Station. NASA astronaut Scott Kelly captured this image and tweeted it out to his followers with this remark: " Day 330 (in space). Tried to only count up. 10 days left tmrw I started #countdown! #GoodNight from @space_station! #YearInSpace

ISS046e038911 (01/10/2016) --- NASA astronaut Scott Kelly (left) and ESA (European Space Agency) astronaut Timothy Peake (right) review images during a procedure to replace a fan pump separator inside one of the U.S. spacesuits aboard the International Space Station. The activity took place inside the Quest airlock where all U.S. based spacewalks begin and end.

ISS043E089469 (04/06/2015) --- NASA astronaut Scott Kelly, one of two One-Year crew members on the International Space Station, has his morning coffee and TV news from the Houston area on Apr. 6, 2015. His tweeted comment with this image: " Morning @space_station with my coffee and news from Earth with @KHOU News Houston and @KHOU Lily Jang".

ISS043E128431 (04/22/2015) --- The International Space Station employs one of the most complex water recycling systems ever designed, reclaiming waste water from astronauts and the environment and turning it into potable water. NASA astronaut Scott Kelly tweeted out this image of part of the innovative device with this remark: " Recycle Good to the last drop! Making pee potable and turning it into coffee on @space station. #NoPlaceLikeHome"

ISS043E294202 (06/10/2015) --- NASA astronaut Scott Kelly is photographed in the Japanese Experiment Module (JEM) holding a sign with the hashtag #whyspacematters. NASA and the United Nations Office for Outer Space Affairs (UNOOSA) have launched a global photography competition to highlight how the vantage point of space helps us better understand our home planet, improve lives, and safeguard our future by aiding sustainable development on Earth.

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)

Expedition 43 NASA Astronaut Scott Kelly checks his smartphone as he walks from the Zvjozdnyj Hotel to the Cosmonaut Hotel for additional training, Thursday, March 19, 2015 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 NASA Astronaut Scott Kelly walks from morning classes at the Cosmonaut Hotel to his crew quarters at the Zvjozdnyj Hotel, Thursday, March 19, 2015 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 NASA Astronaut Scott Kelly plays pool with Russian Cosmonaut Mikhail Kornienko of the Russian Federal Space Agency (Roscosmos) at the Cosmonaut Hotel, Thursday, March 19, 2015 in Baikonur, Kazakhstan. Kelly, Kornienko, and Russian Cosmonaut Gennady Padalka 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 poses for a portrait near a model of the Soyuz rocket, 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 NASA Astronaut Scott Kelly, watches carefully as Russian Cosmonauts Gennady Padalka, and Mikhail Kornienko of the Russian Federal Space Agency (Roscosmos) work on Soyuz training, 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 NASA Astronaut Scott Kelly, left, and Russian Cosmonaut Mikhail Kornienko of the Russian Federal Space Agency (Roscosmos) pose for a photo near a model of the Soyuz rocket during media day, Saturday, March 21, 2015 at the Cosmonaut Hotel in Baikonur, Kazakhstan. Kelly, Kornienko, and Russian Cosmonaut Gennady Padalka 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 (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 listens to an interpreter during an ISS Russian Segment Safety 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)

Expedition 43 NASA Astronaut Scott Kelly prepares to depart the Cosmonaut Hotel after having conducted a television interview, Thursday, March 19, 2015 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 NASA Astronaut Scott Kelly describes his One-Year mission patch to members of the press during media day, Saturday, March 21, 2015 at the Cosmonaut Hotel in Baikonur, Kazakhstan. 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 Mikhail Kornienko of the Russian Federal Space Agency (Roscosmos), left, and NASA Astronaut Scott Kelly talk with staff while relaxing at the Cosmonaut Hotel, Thursday, March 19, 2015 in Baikonur, Kazakhstan. Kelly, Kornienko, and Russian Cosmonaut Gennady Padalka 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, left, plays pool with Russian Cosmonaut Mikhail Kornienko of the Russian Federal Space Agency (Roscosmos), as NASA International Space Station Program Manager for International and Crew Operations Michael Baker looks on at the Cosmonaut Hotel, Thursday, March 19, 2015 in Baikonur, Kazakhstan. Kelly, Kornienko, and Russian Cosmonaut Gennady Padalka 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 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 NASA Astronaut Scott Kelly, left, plays pool with Russian Cosmonaut Mikhail Kornienko of the Russian Federal Space Agency (Roscosmos) at the Cosmonaut Hotel, Thursday, March 19, 2015 in Baikonur, Kazakhstan. Kelly, Kornienko, and Russian Cosmonaut Gennady Padalka 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, left, plays pool with Russian Cosmonaut Mikhail Kornienko of the Russian Federal Space Agency (Roscosmos) at the Cosmonaut Hotel, Thursday, March 19, 2015 in Baikonur, Kazakhstan. Kelly, Kornienko, and Russian Cosmonaut Gennady Padalka 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)

Media document Expedition 43 NASA Astronaut Scott Kelly as he plays billiards during media day, Saturday, March 21, 2015, Baikonur, Kazakhstan. 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 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)

Media document Expedition 43 Russian Cosmonaut Mikhail Kornienko of the Russian Federal Space Agency (Roscosmos), left, and NASA Astronaut Scott Kelly, right, as they play billiards during media day, Saturday, March 21, 2015, Baikonur, Kazakhstan. Kelly, and Russian Cosmonauts Gennady Padalka, and Mikhail Kornienko of 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, plays pool with Russian Cosmonaut Mikhail Kornienko of the Russian Federal Space Agency (Roscosmos) at the Cosmonaut Hotel, Thursday, March 19, 2015 in Baikonur, Kazakhstan. Kelly, Kornienko, and Russian Cosmonaut Gennady Padalka 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 walks from the Zvjozdnyj Hotel to the Cosmonaut Hotel for additional training, Thursday, March 19, 2015 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 NASA Astronaut Scott Kelly takes part in the spin chair training during media day, Saturday, March 21, 2015, Baikonur, Kazakhstan. 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 NASA Astronaut Scott Kelly plays pool with Russian Cosmonaut Mikhail Kornienko of the Russian Federal Space Agency (Roscosmos) at the Cosmonaut Hotel, Thursday, March 19, 2015 in Baikonur, Kazakhstan. Kelly, Kornienko, and Russian Cosmonaut Gennady Padalka 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, left in mirror, and Russian Cosmonaut Mikhail Kornienko, of the Russian Federal Space Agency (Roscosmos) are seen exercising during media day, Saturday, March 21, 2015, Baikonur, Kazakhstan. Kornienko, Kelly and Russian Cosmonaut Gennady Padalka of 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 Ingall

Expedition 43 NASA Astronaut Scott Kelly takes part in the spin chair training during media day, Saturday, March 21, 2015, Baikonur, Kazakhstan. 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 NASA Astronaut Scott Kelly looks out over the Syr Darya river, 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 NASA Astronaut Scott Kelly plays pool with Russian Cosmonaut Mikhail Kornienko of the Russian Federal Space Agency (Roscosmos) at the Cosmonaut Hotel, Thursday, March 19, 2015 in Baikonur, Kazakhstan. Kelly, Kornienko, and Russian Cosmonaut Gennady Padalka 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 waters a tree planted in his honor during media day, Saturday, March 21, 2015, Baikonur, Kazakhstan. 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 NASA Astronaut Scott Kelly plays pool with Russian Cosmonaut Mikhail Kornienko of the Russian Federal Space Agency (Roscosmos) at the Cosmonaut Hotel, Thursday, March 19, 2015 in Baikonur, Kazakhstan. Kelly, Kornienko, and Russian Cosmonaut Gennady Padalka 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 26 Commander Scott Kelly is helped as he exits a Russian all terrain vehicle (ATV) that delivered him to a helicopter from the Soyuz TMA-01M spacecraft shortly after the capsule landed with Kelly and Expedition 26 Flight Engineers Oleg Skripochka and Alexander Kaleri near the town of Arkalyk, Kazakhstan on Wednesday, March 16, 2011. NASA Astronaut Kelly, Russian Cosmonauts Skripochka and Kaleri are returning from almost six months onboard the International Space Station where they served as members of the Expedition 25 and 26 crews. Photo Credit: (NASA/Bill Ingalls)

The Kennedy Space Center Visitor Complex kicked off its "Summer of Mars" promotion with a ceremony which included former NASA astronaut Scott Kelly. During his appearance, Kelly shared some of his experiences during a one-year stay aboard the International Space Station. The "Summer of Mars" program is designed to provide guests with a better understanding of NASA's studies of the Red Planet.

The Kennedy Space Center Visitor Complex kicked off its "Summer of Mars" promotion with a ceremony which included former NASA astronaut Scott Kelly. During his appearance, Kelly shared some of his experiences during a one-year stay aboard the International Space Station. The "Summer of Mars" program is designed to provide guests with a better understanding of NASA's studies of the Red Planet.

The Kennedy Space Center Visitor Complex kicked off its "Summer of Mars" promotion with a ceremony which included former NASA astronaut Scott Kelly. During his appearance, Kelly shared some of his experiences during a one-year stay aboard the International Space Station. The "Summer of Mars" program is designed to provide guests with a better understanding of NASA's studies of the Red Planet.

The Kennedy Space Center Visitor Complex kicked off its "Summer of Mars" promotion with a ceremony which included former NASA astronaut Scott Kelly. During his appearance, Kelly shared some of his experiences during a one-year stay aboard the International Space Station. The "Summer of Mars" program is designed to provide guests with a better understanding of NASA's studies of the Red Planet.

Expedition 25 Flight Engineer Scott Kelly performs the traditional door signing Thursday, October 7, 2010 at the Cosmonaut Hotel in Baikonur, Kazakhstan. Kelly was launched onboard the Soyuz rocket the following morning with Expedition 25 Soyuz Commander Alexander Kaleri and Flight Engineer Oleg Skripochka on a mission to the International Space Station (ISS). Photo Credit: (NASA/Carla Cioffi)