Three members of the International Space Station’s Expedition 54 crew returned to Earth on Feb. 27, 2018. Riding in their Soyuz MS-06 spacecraft, the trio blazed through the atmosphere and landed on the snow-covered Kazakh Steppe in Kazakhstan.
Russian cosmonaut Alexander Misurkin of Roscosmos and astronauts Joe Acaba and Mark Vande Hei of NASA returned after spending 168 days in space aboard the ISS as part of Expedition 53 and 54. In the nearly six months since their Sept. 12, 2017, launch, the crew performed hundreds of experiments, including a “record-setting week of research that surpassed 100 hours.” Moreover, the trio was involved in record-setting spacewalks and received cargo from four different visiting vehicles.
Misurkin, who was on his second flight into space, took over command of the outpost on Dec. 14, 2017, when the crew of Soyuz MS-05 departed. In similar fashion, on Feb. 26, 2018, Misurkin handed off his command of the outpost to fellow cosmonaut Anton Shkaplerov, who remains aboard ISS along with NASA astronaut Scott Tingle and Japan Aerospace Exploration Agency astronaut Norishige Kanai.
During the change of command ceremony, Misurkin continued a tradition started by Expedition 52 commander Fyodor Yurchikhin in September 2017—passing the “key to the station” to the next commander. That key is actually a wrench used to open the hatch between the station and a Soyuz spacecraft.
The next day, the departing trio said their farewells and entered Soyuz MS-06. Hatches between the spacecraft and space station were officially closed at 2:58 p.m. EST (19:58 GMT) Feb. 27. For the next several hours, the Soyuz crew performed leak checks and donned their Sokol launch and entry suits.
Finally, at 6:08 p.m. EST (23:08 GMT), Soyuz MS-06, which was located at the zenith port of the Poisk module on the Russian segment of the outpost, undocked and began a series of departure burns to leave the vicinity of the complex.
The moment the Soyuz undocked was when Expedition 54 officially ended and Expedition 55 began. Shkaplerov, Tingle and Kanai will be joined a few weeks later by the crew of Soyuz MS-08, which is scheduled to launch from Baikonur Cosmodrome on March 21, 2018.
After drifting away from the ISS for about 2.5 hours, Soyuz MS-06 was ready to perform its de-orbit burn. This occurred at 8:38 p.m. EST (01:38 GMT Feb. 28).
The 4 minute, 39 second firing of the Soyuz’s main engine slowed the spacecraft down by about 128 meters per second, enough to enter the atmosphere to drop out of orbit.
At 9:05 p.m. EST (02:05 GMT), the spacecraft’s three parts—the orbital module, descent module, and service module—separated. Only the descent module, with its crew, is designed to survive reentry.
Once the capsule was around 100 kilometers in altitude, it was low enough for the friction of the atmosphere to begin rapidly slowing the spacecraft. At that moment, the Soyuz was traveling some eight kilometers per second. Protected by a heat shield, in just seven minutes the spacecraft and its occupants quickly decelerated to just 2.2 kilometers per second, causing the trio to feel around 4.5 times the force of gravity.
Soon, the Soyuz was deep enough in the atmosphere and its velocity slow enough for a series of parachutes to deploy. This culminated in a main parachute with an area of 1,000 square meters to unfurl, ultimately slowing the capsule down to a mere 6.5 meters per second.
However, this alone was not enough to ensure a safe landing. While descending, the crew seats were pushed forward in order to better absorb the impact with the ground. Additionally, soft landing jets fired about one meter off the ground to cushion the landing further. Touchdown officially occurred at 9:31 p.m. EST (02:31 GMT).
The Soyuz often lands on its side as wind typically pulls the parachute several dozen feet with the still-attached capsule. However, conditions at the site, while snowy and a brisk minutes 1.1 degrees Celsius, were overcast with a gentle to moderate breeze. As a result, the capsule remained upright.
Once Russian search and rescue teams arrived, they quickly began extracting the crew. The first out was Misurkin, as he was in the center seat. He was followed by Acaba and then Vande Hei. All three were carried to reclining chairs to get used to the effects of gravity before being carried to a nearby inflatable medical tent for health evaluations.
Soon after that, the each crew member was loaded onto a separate helicopter for transportation to the nearby city of Dzhezkazgan, Kazakhstan. There, the two NASA astronauts will part ways with their Russian colleague as they head to their respective space agency headquarters.
Misurkin has now spent 334 days in space. During Expedition 54, he and Shkaplerov performed a spacewalk to upgrade a high-gain antenna on the Russian Orbital Segment. Because of complications, the extravehicular activity lasted much longer than anticipated. In fact, when all was said and done the planned 6.5-hour excursion actually lasted 8 hours, 7 minutes—the longest Russian spacewalk to date and the fifth-longest in human spaceflight history.
Acaba was on his third spaceflight and his second stay aboard the ISS. During this mission, he performed one spacewalk to lubricate an end effector on the robotic Canadarm2 and install new camera’s around the complex, according to NASA.
Vande Hei was on his first mission to space. During his stay, he logged four spacewalks. Each involved work to upgrade Canadarm2 to ensure the operation of the robotic device lasts for the remainder of the space station’s expected life.
The three remaining ISS crew members will be joined in several weeks by Russian cosmonaut Oleg Artemyev, and NASA astronauts Richard Arnold and Andrew Feustel. After they launch in Soyuz MS-08, the trio will spend two days catching up with the outpost before docking on March 23, 2018.
NOTE: While this article was written by Derek Richardson, it was originally published at SpaceFlight Insider. Feel free to head over there to read all the stuff they write about!