With three space station aircraft heading home Sunday after a 168-day mission, three new crew members made final preparations for the launch three days later to increase the laboratory crew to six in one rapid turnover that will avoid any major interruption of the research activity.
Commander Soyuz MS-07 / 53S Anton Shkaplerov, flight engineer Scott Tingle of NASA and Japanese astronaut doctor Norishige Kanai plan to tie up to their shuttle and uncouple from the Rbadvet module facing Earth at 5:16 I'm ET on Sunday, leaving the commander of Expedition 56 Drew Feustel, Ricky Arnold and Oleg Artemyev behind.
Launched on December 17 Shkaplerov and his companions plan to fire their braking rockets for four minutes and 40 seconds. at 7:47 a.m., reducing the speed of the ship by 286 mph and dropping the side farthest from the orbit in the atmosphere.
If all goes well, the central crew module will make a parachute and rocketship landing in the Kazakh steppe near the town of Dzhezkazgan at 8:40 a.m. After the initial medical checks, Tingle and Kanai will be taken back to the Johnson Space Center in Houston, while Shkaplerov will head to Star City, near Moscow, for an interrogation.
"I can" I think Expedition 55 is over, "Tingle wrote in a recent blog post." Last night we had our last movie night. The whole team met at Node 2 and saw Avengers Infinity Wars & # 39; (sic) on the big screen. We enjoyed the company of others … and this was a welcome break from the daily routine. of trying to complete the necessary stowage, maintenance and science activities while preparing for departure. "
During his last full weekend in space, Tingle said:" I cut my hair. We usually clean our spaces every weekend to make sure we can maintain a decent level of organization, efficiency and morale. This weekend is no different, and it's time to vacuum all our filters and vents. You will be surprised at what we find! "
During a brief command change ceremony on Friday, Shkaplerov thanked Feustel's crew for their support and handed a ceremonial key to the outpost.
"It's been three months since we started the 55th Expedition (when) I took command of the space station," said Shkaplerov. "We are going back to Earth … I want to thank you very much, Drew, Ricky and Oleg, for your friendship, for your help every day, my crewmates, my space brothers, I am very proud to be part of our Soyuz team "
Feustel thanked Shkaplerov in return "for welcoming us to the ISS, taking care of us, making sure we were ready to work when we arrived, made the transition without problems".  "We appreciate your patience, your guidance and your leadership, and we look forward to a safe and smooth landing for you," he added.
With the landing, Tingle and Kanai, both completing their first space flight, will have logged 168 days in space during a trip spanning 2,688 orbits and 71.2 million miles since launch. Shkaplerov, a veteran of two previous visits to the station for a full year, will have logged 532 days off the planet.
The three men made an individual spacewalk each during their stay, welcomed four visiting vehicles, one Soyuz and three unmanned cargo ships, and supervised the departure of a similar number, along with the completion of a complete list of scientific investigations.
With the departure of Shkaplerov and his crewmates, Feustel, Arnold and Artemyev, were launched at the station on March 21 aboard the Soyuz spacecraft MS-08, they will have the laboratory for they just five days before a new crew arrives.
The Soyuz commander MS-09 / 55S Sergey Prokopyev, the German flight engineer Alexander Gerst, representing the European Space Agency, and the NASA astronaut doctor Serena Auñón-Chancellor are scheduled for launch from the Cosmodrome Baikonur, 250 miles southwest of Dzhezkazgan, at 7:12 a.m. (5:12 p.m., local time) Wednesday.
When climbing directly to the plane of the orbit of the space station, the Soyuz will be released from its carrier rocket eight minutes and 45 seconds after takeoff. Over the next two days, Prokopyev and Gerst will monitor an automated appointment, catching up with the space station early Friday. They plan to dock at Rbadvet around 9:07 a.m.
After a traditional video conference with friends and family in Moscow, the newcomers will receive a security report before the six crew members go to work.
Gerst He spent 165 days aboard the station in 2014, but Prokopyev and Auñón-Chancellor will make their first flights.
Auñón-Chancellor, a veteran flight surgeon, was originally badigned to a mission later this year, but was moved to the Soyuz MS-09 crew after one of his original crew, astronaut Jeanette Epps, was suddenly beaten by the Prokopyev-Gerst crew in January.
NASA did not provide any explanation for the last crew change, Epps had no public comment and Auñón-Chancellor only said that he planned to be ready for the launch despite an accelerated training program and that he was already on good terms with his new crewmates.
"It's a relatively short amount of crew time allocation, but I've known these guys for a long time," he said. "Alex and I were selected in the same clbad (from astronauts) and even from the beginning, when I started training in Russia, I also met Sergey, so for us, honestly, this is like a big family. Absolute, it was extremely gentle.
"I feel like I've been working with these guys forever," he added. "It's been very easy. … Our families have met several times. It has been a lot of fun "
Auñón-Chancellor came to NASA in 2006, working as a contract flight surgeon, spent more than nine months in Star City supporting medical operations with members of the space station and participated in survival training in water in Ukraine.
After being selected as a NASA astronaut in 2009, he spent two months in Antarctica looking for meteorites as part of a scientific expedition and then served as an aquanauta aboard the Aquarius underwater laboratory.  In a CBS News satellite interview during his final training in Moscow shortly before leaving for Baikonur, Auñón-Chancellor said he was well prepared and awaiting launch.
"The Soyuz is a wonderfully robust and redundant vehicle," he said. "The best thing is the Russians have been flying for a long time, just like us, and we have been flying together for a long time. They do a great job here in Star City preparing an international team … to act in an operational environment and follow all the same rules and procedures to make sure the mission is successful. "
Regarding security and reliability of the Russian Ferry, "I have complete faith in the Soyuz," he said. "It is a wonderfully robust vehicle."
Gerst said he was excited to have a second chance to fly in space.
that are flown to space wants to return, "he said. Being in space is such a special feeling that you can not even attribute it to just one thing. It's not just about floating, it's not just about observing this beautiful planet, it's not just the perspective we have, but knowing where we are. "
Before his first flight, he said:" I saw space as Something very special, I thought that this was a very special place to go. When I was there, I really learned that it was the opposite. Space is everywhere, the universe is gigantic, it is black and it is empty. Of course, there are quite a few interesting places to go to, like the moon and Mars, and we're going to go there, but most of it is empty. "
" So the really special place, and that's what you realize in space, is actually our planet Earth, "said Gerst." Seeing that from the outside, seeing that from a step back, made me realize that. That was a very beautiful idea. "