As NASA astronaut Scott Kelly and Russian cosmonaut Mikhail Kornienko wrap up their mission aboard the International Space Station, Kelly's fellow NASA astronaut Tim Kopra has now assumed command of the habitable satellite.
On Leap Day, Kelly handed over the reins of the ISS to Kopra in a traditional Change of Command ceremony at 3:15 PM EST, effectively relinquishing his post as the commander of the space station.
"It's kind of hard to believe that we've been here for two and a half months, and it's only a small portion of Scott and Mikhail's time here," Kopra said in the live broadcast of the Change of Command ceremony. "But I have to say that it's an honor and privilege to assume command of the International Space Station."
Kopra also thanked Kelly for his leadership and for being a great role model in every aspect.
The task of the commander -- the highest authority on the ISS -- is to direct activities for the crew members, provide regular updates to the flight director, maintain the peace, and prevent a space mutiny. Kelly, who has spent the highest number of consecutive days in space for American astronauts, has been commander of the ISS for his previous missions, Expeditions 45 and 46.
Kornienko and Kelly were blasted off into space on March 27 last year for their one-year mission.
When it officially ends on March 1, Kelly will have spent 520 days aboard the ISS, with 340 of it coming from this recent mission. Kornienko will also have spent 340 days in space.
Future Mars Missions
Kopra will be starting Expedition 47 aboard the ISS as the Soyuz spacecraft carrying Kelly, Kornienko and his fellow cosmonaut Sergey Volkov undocks from the ISS on Tuesday.
The Soyuz spacecraft will plummet through Earth's atmosphere and land at the Baikonur Cosmodrome in Kazakhstan on Tuesday night. Kelly will return to Mission Control in Houston on Wednesday.
Kelly, Kornienko and Volkov will have to re-acclimate to Earth's living conditions after spending quite a long time aboard the space station.
These spacemen have an especially specific task: to help researchers figure out whether we could hit the ground running for future Mars missions.
For instance, Kelly will try to pop up from a lying position and stand still for three minutes. He will be taking a crack at a mini-obstacle course, attempting to walk in a straight line, heel to toe.
NASA considers the task as crucial for future Mars explorers who will have to spend so much time in space and won't have the help of a welcoming committee.
Kelly believes that scientists will learn a lot about longer-duration spaceflight and how it will someday take us to Mars. In fact, Kelly and his twin brother Mark are involved in research to study the impact of living in space for future Mars missions.
"I'd like to think that this is another of many steppingstones to us landing on Mars sometime in our future," Kelly said during his final news conference from orbit.
The tests on Kornienko and Kelly should provide some answers to questions like: what could Mars explorers do when they arrive on the red planet? Could they jump up and down? Could they even open a hatch? Could they immediately do a spacewalk?
All these questions were asked by Dr. Stevan Gilmore, the lead surgeon who will be receiving Kelly.
The tests will include blood draws, heart monitoring and other medical exams, and will continue for weeks.
We will surely miss Kelly's Twitter updates from space, but returning home and being back with his family after a long period definitely feels good.
Watch below as Kelly hands over the command to Kopra.
