With a mission that was anything but mundane, Soyuz MS-09 with its three-person crew returned to Earth after more than 6 months in orbit on the International Space Station. The Soyuz MS-09 vehicle rose to high public profile in August when a hole that resulted in a small atmospheric leak aboard the Station was discovered in its Orbital Module.

That hole was determined to have been drilled on the ground during the spacecraft’s manufacturing and led to a rather dramatic spacewalk earlier in December that saw cosmonauts cut into the protective casing around MS-09’s Orbital Module to conduct further investigation of the issue.

Wrapping up its mission, Soyuz MS-09 and its three-person crew from Russia, ESA, and NASA, undocked from the International Space Station at 20:42 EST (01:42 UTC on Thursday, 20 December) before landing on the Kazakh steppe at around 00:03 EST (0503 UTC) on Thursday, 20 December.

Soyuz MS-09 – a profile in intrigue:

When Soyuz MS-09 launched to the Space Station on 6 June 2018, the mission seemed like most others that had come before: nominal in almost every regard with the spacecraft successfully delivering its three-person crew to the International Space Station.

But the spacecraft’s quiescent existence was shattered on 29 August 2018 when a small air leak was identified by ground controllers throughout the International Space Station, a leak that was quickly traced to a 2 millimeter hole in the Orbital Module of Soyuz MS-09.

The crewed Soyuz transportation vehicles are comprised of three primary sections, the Orbital Module at the top which physically connects the vehicle to the International Space Station, the Descent Module in the middle within which crews ride to and from orbit, and the Instrumentation and Propulsion Module which contains the propulsion, power, electrical, and avionics systems for the craft.

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At the end of nominal missions, the only part of a Soyuz spacecraft that survives reentry is the Descent Module, with the Orbital and Instrumentation and Propulsion Modules burning up during atmospheric reentry.

Once the hole was found, Station crew members immediately identified it as having been caused by a drill and reported the presence of material in the hole suggesting that is had already been sealed on the ground and that that ground seal had given way.

Over the objections of then-NASA Station Commander Drew Feustel and NASA requests to hold off on permanent repairs until an investigation and better understand of the hole was determined, Russian cosmonauts and Russian Mission Control quickly sealed the hole using an epoxy sealant.

After those repairs, no further leaks were detected aboard the Station aside from the nominal atmospheric decay that occurs during each of the Station’s 16 daily orbital day to night passes.

Official confirmation that the hole was caused by a drill was announced on 4 September 2018, though it could not be determined whether the hole was drilled intentionally during manufacturing – aka, sabotage – or was the result of a manufacturing error.

Despite the admission, what was abundantly clear was that workers on the ground had identified the hole and sealed it in an attempt to cover it up, thus allowing Soyuz MS-09 to pass all pressurization and leak checks prior to launch.

The presence of the hole and its undocumented fix also raised serious concerns about the safety and quality control methods in place within Roscosmos in building the as-yet-still only vehicle capable of transporting crew to and from the International Space Station since the retirement of the Space Shuttle fleet in July 2011.

Perhaps serendipitously, the presence of the hole in Soyuz MS-09’s Orbital Module is arguably the best place the hole could have been since the Orbital Module does not survive atmospheric reentry.

In short, the fact that the hole is in the Orbital Module means that it poses no threat to the safe return of Alexander Gerst (ESA), Sergey Prokopyev (Roscosmos), and Serena Auñón-Chancellor (NASA).

However, the fact that the hole made it through safety and quality assurance checks before launch also raised serious questions of whether other holes exist throughout the Soyuz MS-09 vehicle – a question which cannot be answered with certainty until the craft returns to Earth.

An even greater spotlight was thrown onto Soyuz MS-09 on 11 October 2018 when the Soyuz MS-10 crew vehicle was forced to perform an in-flight abort to pull itself away from its failing Soyuz rocket just over two minutes into flight.

The Soyuz MS-10 launch failure, also attributed to a lack of quality control within Roscosmos, only strengthened and raised the concerns of safety and quality assurance within the Russian human space program.

Nonetheless, Roscosmos was quickly able to determine the reason for the Soyuz MS-10 launch failure and successfully launched the Soyuz MS-11 crew up to the International Space Station on 3 December, setting up a delayed but still more or less on time landing for Soyuz MS-09 on 20 December.

However, since the Soyuz MS-09 Orbital Module will not survive reentry, Roscosmos was forced to perform a spacewalk, or EVA, to tear into the outer protective layer surrounding the hole to take photographs and collect samples that will aid in the still-ongoing official investigation of how the hole was drilled in the first place and how the undocumented ground repair occurred.

The rather dramatic looking spacewalk took place on 11 December, with Russian cosmonauts Oleg Kononenko and Sergey Prokopyev cutting into the thermal blankets and pulling away insulation in order to examine the Orbital Module’s outer hull.

The EVA clearly revealed the hole, allowing the needed samples and photographs to be collected without issue.

Soyuz MS-09 landing:

With Soyuz MS-09 now undocked from the International Space Station, the crewed craft performed two orbits of Earth and various small trajectory burns to bring itself into proper alignment for its critical deorbit burn.

The more than 4 minute long deorbit burn began at 23:09 EST on Wednesday, 19 December (0409 UTC on Thursday, 20 December) and decreased Soyuz MS-09’s velocity to lower the craft’s perigee, point of closest approach to Earth’s surface, into Earth’s atmosphere at a precise point to allow the Soyuz’s Descent Module to land at its primary location on the steppes of Kazakhstan.

Following the deorbit burn and a brief coast, commands were sent to separate Soyuz MS-09 into its three constituent parts, with the Orbital Module (containing the hole) and the Instrumentation and Propulsion Module burning up in Earth’s atmosphere while the Descent Module orients itself heatshield first for atmospheric entry.

During the Descent Module’s reentry, the immense speed of the craft combined with friction with air molecules will create a plasma flow around the vehicle which can – and usually does – cause temporary communication blackouts with the crew.

Perhaps more importantly than other Soyuz reentries, it is important to stress that these communication blackouts are to be expected and are not, in themselves, any cause for concern during the entry process.

Also important to stress is that aside from the nominal reentry profile, the Soyuz’s Descent Module can also perform what is known as a ballistic style reentry – a much steeper and harsher reentry – designed to get a crew to the ground as quickly as possible if a systems or orientation issue is identified by the spacecraft’s computers.

This type of ballistic reentry was last seen during the Soyuz MS-10 launch abort in October and has previously occurred in October 2007 and April 2008 during back-to-back Soyuz landings of International Space Station crew members.

Had a ballistic reentry occur during the Soyuz MS-09 landing , it wouldn’t be indicative of or immediately connected to the hole in the Orbital Module, which will have already been jettisoned by the point a ballistic reentry would be triggered during the entry sequence.

However, a nominal reentry and landing occurred, with Soyuz MS-09’s Descent Module touching down under parachute and last-second retro rocket firing at around 00:03 EST (0503 UTC) on Thursday, 20 December on the Kazakh steps.</s>Three people made a fiery return to Earth in the Soyuz MS-09 capsule after spending 197 days in space, mostly aboard the International Space Station.

Russian cosmonaut Sergey Prokopyev, NASA astronaut Serena Aunon-Chancellor and European Space Agency astronaut Alexander Gerst landed in a frigid Kazakhstan at 12:03 a.m. EST (5:02 GMT) Dec. 20, 2018, in their Soyuz MS-09 spacecraft’s descent module. Conditions on the ground were cold and overcast with a temperature of about 3 degrees Fahrenheit (minus 16 degrees Celsius) and as much as 6 inches (15 centimeters) of snow on the ground.

“On the eve of the 50th anniversary of human kind’s first voyage to the Moon, a multinational crew returns to Earth after spending more than a half-year in space,” said NASA Public Affairs Officer Rob Navias during NASA TV coverage of the landing.

Prokopyev, Gerst and Aunon-Chancellor launched into orbit from Baikonur Cosmodrome in Kazakhstan on June 6, 2018. After spending two days catching up with the ISS, they docked with the Rassvet module to join NASA’s Drew Feustel and Ricky Arnold and Russia’s Oleg Artemyev as part of Expedition 56. When Feustel, Arnold and Artemyev returned to Earth on Oct. 4, 2018, Prokopyev, Aunon-Chancellor and Gerst formed the first part of Expedition 57.

Aunon-Chancellor, 42, and Prokopyev, 43, completed their first spaceflight. This was the second flight for 42-year-old Gerst, however, who now holds the record for the most cumulative days in space by a European Space Agency astronaut at 362 days.

In addition to conducting hundreds of science experiments, the trio oversaw multiple visiting vehicle arrivals and departures and had to deal with a minor leak aboard the space station, which originated from a hole on the Soyuz MS-09 spacecraft itself.

At about 7 p.m. EDT (23:00 GMT) Aug. 29, 2018, ground controllers in Houston and Moscow detected signs of a “minute pressure leak” somewhere in the orbiting complex. According to NASA, the pressure reduction was slow enough that it was decided to allow the crew to continue sleeping and address the issue once they woke up.

“When the crew was awakened at its normal hour this morning, flight controllers at Mission Control in Houston and at the Russian Mission Control Center outside Moscow began working procedures to try to determine the location of the leak,” NASA said in a statement Aug. 30.

After discussions between the crew and mission control centers in Houston and Moscow, it was decided to have the cosmonauts apply an epoxy substance with medical gauze around the opening. Throughout the rest of the Soyuz MS-09 stay at the ISS, it showed no signs of further leakage.

The cause of the hole was thought to be caused by human hand, likely from someone who worked on the spacecraft on the ground. However, the exact circumstances are not yet known. Either way, the hole was on the Orbital Module of the Soyuz, which was not needed for re-entry. That being said, Roscosmos still wanted to examine and get a sample of the hole and epoxy used to seal it from the outside of the spacecraft.

That was to be done by spacewalking cosmonauts initially in November. However, the in-flight abort of the Soyuz MS-10 crew that was initially to join Expedition 57— NASA astronaut Nick Hague and Russian cosmonaut Aleksey Ovchinin — caused the outing to be pushed to Dec. 11, several days after Soyuz MS-11 launched with Russian cosmonaut Oleg Kononenko, NASA astronaut Anne McClain and Canadian Space Agency astronaut David Saint-Jacques.

During a 7 hour, 45 minute spacewalk Prokopyev and Kononenko used a knife to peel back thermal insulation in order to inspect the area of the Soyuz MS-09 spacecraft where the small leak occurred. This also involved using shears to cut away at the micrometeoroid shielding.

When it finally came time for the crew to leave, Gerst handed command of the space station over to Kononenko, he along with McClain and Saint-Jacques will form Expedition 58. That handover occurred during a “change of command” ceremony on Dec. 18.

The next day at 5:30 p.m. EST (22:30 GMT), the departing trio said farewell to the soon-to-be Expedition 58 crew and the hatches between Soyuz and ISS were closed. Three hours later at 8:40 p.m. EST Dec. 19 (1:40 GMT Dec. 20), the spacecraft undocked from the Rassvet module.

After two separations burns and three hours of coasting away from the space station, the Soyuz MS-09 performed its deorbit burn at 10:10 p.m. EST Dec. 19 (4:10 GMT Dec. 20). This 4 minute, 37 second burn slowed the vehicle down by 420 feet (128 meters) per second — just enough to lower its orbit enough to intersect with the atmosphere.

Just before this intersection — called entry interface — the three main parts of the spacecraft — the Orbital Module, Descent Module and Service Module — separated. Only the Descent Module with the crew inside is designed to survive re-entry.

During the re-entry process, the crew experienced a peak g-load of about 3.8 times that of normal Earth gravity for a brief period. Over about seven minutes, the spacecraft — protected by a heat shield — was slowed from about 5 miles (8 kilometers) per second to about 1.3 miles (2.2 kilometers) per second.

Once Soyuz was slow enough and deep enough in the atmosphere, a series of parachutes began to deploy, culminating with the main parachute for a several-minute slow descent to the ground.

While the spacecraft descended, the crew seats were pushed forward to better absorb the upcoming impact with the ground. Additionally, soft landing jets fired about a meter above the surface to cushion the landing further. Upon touchdown, the capsule landed in an upright position.

Within minutes, Russian search and rescue teams arrived and landed near the capsule to begin the recovery process. The three were pulled out one by one with Prokopyev emerging first, followed by Aunon-Chancellor and then Gerst.

The trio were placed in couches for a brief medical check. However, that didn’t last long as the cold temperatures prompted recovery teams to quickly move the three into a nearby inflatable medical tent.

After that, each crew member is expected to be transported to the nearby city of Dzhezkazgan, Kazakhstan. There, they will begin to part ways and head back to their respective home countries.</s>"Landing has taken place", the text on a big screen located in the main hall of the center read.

Both employees of the center and guests who were present there burst into applause.

Russian cosmonaut Sergey Prokopyev, German astronaut Alexander Gerst, and NASA astronaut Serena Aunon-Chancellor have delivered to Earth the pieces of evidence that Russian state space corporation Roscosmos and investigators need for their probe into the microfracture found in the orbital module of the Soyuz MS-09 spacecraft in late August.

READ MORE: Soyuz Carrier Rocket With French Spy Satellite Blasts Off From Kourou Spaceport

Earlier in December, the cosmonauts carried out a spacewalk to examine the hole in the spacecraft, found in late August. The cosmonauts cut off three pieces of micrometeoroid protection to take samples of the sealer and the surface surrounding the microfracture.</s>If you would like to see more articles like this please support our coverage of the space program by becoming a Spaceflight Now Member . If everyone who enjoys our website helps fund it, we can expand and improve our coverage further.

STORY WRITTEN FOR CBS NEWS & USED WITH PERMISSION

A Russian cosmonaut, a German flight engineer and a NASA astronaut undocked from the International Space Station and plunged back to Earth overnight Wednesday, landing on the snowy steppe of Kazakhstan to wrap up a six-month mission.

Blocked from view by low clouds and wind-blown snow, the Soyuz MS-09/55S spacecraft, suspended beneath a large orange-and-white parachute, touched down on the frigid steppe near the town of Dzhezkazgan at 12:02 a.m. EST Thursday (GMT-5; 11:02 a.m. local time), three-and-a-half hours after departing the space station.

Russian recovery crews and medical personnel, along with U.S. and European Space Agency support teams, quickly rushed to the spacecraft to help the returning crew members out of the cramped crew compartment as they began their re-adaptation to the unfamiliar tug of gravity.

Soyuz commander Sergey Prokopyev and NASA physician-astronaut Auñón-Chancellor logged 196 days 17 hours and 50 minutes off the planet during their first space mission while German astronaut Alexander Gerst, veteran of an earlier stay aboard the station in 2014, pushed his total to 362 days of cumulative time aloft.

Asked what she was looking forward to the most, Auñón-Chancellor said “that’s easy. Family. That’s what you miss the most up here.”

“I don’t think you ever really get used to it,” she told CBS News in an interview last month. “You have reminders, we have pictures, we get special video conference calls, but it’s not like being in the arms of your loved ones.”

Second on her list behind family “would be just the feelings of Earth,” she said. “For example, the wind, the rain. We were watching a video the other day and I remember being very jealous of watching somebody stand by the ocean because I knew they could feel the wind and smell the sea. And we can’t do that up here.”

She got her wish to “feel the Earth” right away. The Soyuz landed in cold, cloudy conditions with temperatures in single digits, a sub-zero wind chill and up to a half foot of snow in the area.

As usual with Soyuz landings, the crew members were carried to nearby recliners and bundled in blankets for initial medical checks and satellite phone calls home to friends and family.

All three were expected to be flown by helicopter to Dzhezkazgan for an official welcome home ceremony. Prokopyev then planned to head back to Star City near Moscow while Gerst headed for Cologne, Germany. Auñón-Chancellor will return to her home near the Johnson Space Center in Houston.

Asked what she will miss the most about life aboard the station, Auñón-Chancellor said “it sounds kind of simple, but floating everywhere is pretty awesome.”

“At first when you get up here you’re sort of this ungraceful ballerina who can’t manage anything … but this is my favorite part,” she said, turning a slow flip aboard the station. “It lets you work in three dimensions, and you just realize what your body’s able to accomplish up here that you just don’t do on Earth.

“That is what I’m going to miss the most. Of course, looking outside and seeing the Earth is absolutely beautiful. But watching the way the human body adapts to being up here is amazing.”

Left behind in orbit with the departure of the Soyuz MS-09 crew were Expedition 58 commander Oleg Kononenko, Canadian astronaut David Saint-Jacques and NASA astronaut Anne McClain. They originally expected to launch last week, joining cosmonaut Alexey Ovchinin and Nick Hague aboard the station.

But Ovchinin and Hague were victims of a launch abort Oct. 11, the first for a Soyuz spacecraft since 1983. Instead of reaching the station and joining Gerst, Prokopyev and Auñón-Chancellor, Ovchinin and Hague were forced to make an emergency landing near Dzhezkazgan, throwing a wrench into the carefully planned crew rotation schedule.

Russian engineers quickly traced the problem to the system used to control the separation of the four liquid-fueled strap-on boosters making up the Soyuz FG booster’s first stage. A fix was relatively straight forward.

After assessing multiple options, Russian managers opted to move up launch of Kononenko’s crew from Dec. 20 to Dec. 3 and to delay the departure of Gerst and his crewmates from Dec. 13 to Dec. 20.

Roscosmos, the Russian space agency, also moved up the next flight in the sequence. That mission, originally planned for early April, was to have carried Russian commander Oleg Skripochka, NASA astronaut Christina Koch and a United Arab Emirates guest astronaut to the station.

Instead, Ovchinin and Hague will join Koch aboard the Soyuz MS-12/58S spacecraft, launching to the station at the end of February. Until then, Kononenko Saint-Jacques and McClain will have the station to themselves.

In an interview with CBS News at his home in Houston, Hague said he had full confidence in the Soyuz’s safety systems and that he was looking forward to fulfilling his mission.

“What we’re doing up there on the space station every day, it’s important,” he said. “We’re trying to open humanity’s eyes, discover new things, make life better on the ground and push farther into the universe. That’s a really important thing to be doing, and it benefits so many people. So you accept the risk because you believe in what you’re doing.”

His wife, Catie, agreed, but said she was still nervous about the idea of her husband riding a rocket into space.

“I was very nervous (during the October launch), and I’m still nervous,” she said. “There’s risk, there’s a lot of risk with what they do, and to be on the outside of that looking in, where you have absolutely no control, is scary. It’s scary.

“But I trust him,” she said, “I trust his training, I trust his commander Alexey implicitly, and I know everybody is really invested in their safety.”

It wasn’t just the Soyuz MS-10 spacecraft that gave the Russians problems. The Soyuz MS-09 ferry ship that Prokopyev, Gerst and Auñón-Chancellor are relying on for their trip home had trouble of its own last August when sensors aboard the station detected a slight drop in the lab’s air pressure.

The leak was not deemed serious enough to wake the crew, but the next morning the four astronauts and two cosmonauts making up the Expedition 56 crew traced the leak to the upper “orbital” module of the Soyuz MS-09 spacecraft.

Photographs of the hole that were downlinked by the station crew showed what appeared to be a drilled-out penetration in an interior panel with several nearby gouges like those that would be caused by a drill skipping across a surface before digging in.

Dmitry Rogozin, the director of Roscosmos, raised eyebrows when he did not immediately rule out the station’s crew members among possible suspects. He said “it is a matter of honor for Energy Rocket and Space Corporation (Soyuz builder RSC Energia) to find the one responsible for that, to find out whether it was an accidental defect or a deliberate spoilage, and where it was done – either on Earth or in space.”

As one might expect, Drew Feustel, the commander of the station at the time, told interviewers his crew had nothing to do with the leak other than plugging it, and no one since then has suggested the possibility of any such involvement.

In any case, Prokopyev and fellow cosmonaut Oleg Artemyev, acting on instructions from the Russian mission control center, plugged the hole with gauze soaked in epoxy. The plug held, and flight controllers later boosted cabin air pressure back to normal levels.

The crew was never in any danger, officials said, and a safe re-entry by the Soyuz MS-09 spacecraft has never been in question because of the leak.

In a normal entry, the three modules making up a Soyuz spacecraft — the upper orbital section the crew compartment and the lower propulsion module — separate from each other just before falling back into the discernible atmosphere.

The upper and lower modules burn up while the descent module, the only one protected by a heat shield, continues on to touchdown. For the Soyuz MS-09 entry, the crew planned to follow normal practice, closing the hatch to the upper module before departing the space station. Even if a leak opened back up, it would have no effect on the sealed-off descent module.

But Russian engineers still wanted to inspect the exterior of the Soyuz’s orbital module to find out if any of the epoxy had made it all the way through the hole and to collect any clues that might be available on the exterior.

By moving launch of Kononenko and his crewmates up to Dec. 3, and delaying the departure of the Gerst crew, the Russians ensured enough time with a full complement of crew members for a spacewalk by Prokopyev and Kononenko to do just that.

The cosmonauts ventured outside the station on Dec. 11 and cut through insulation and micrometeoroid shielding on the orbital revealing the site of the leak. They collected samples of the extruded epoxy and any chemical traces on the hull near the hole that will be returned to Earth for laboratory analysis.</s>Russian spacecraft Soyuz MS-09 with three crew members onboard landed successfully in Kazakhstan Thursday, the European Space Agency said.

Russian astronaut Sergey Prokopyev, United States' Serena Aunon-Chancellor of the NASA, and German Alexander Gerst of the ESA, returned from the International Space Station in the spacecraft after staying in space for 197 days.</s>MOSCOW - Russian spacecraft Soyuz MS-09 has successfully landed in Kazakhstan, bringing back the three astronauts who have completed their missions on the International Space Station (ISS), the Russian mission control centre said Thursday.

"The landing section with Roscosmos cosmonaut Sergei Prokopyev, NASA astronaut Serena Aunon-Chancellor and astronaut of the European Space Agency Alexander Gerst has landed," it was quoted by local media as saying.

On June 6, Russia successfully launched its Soyuz MS-09 spacecraft to the ISS. The three-member crew had lived on it for the scheduled 187 days.

Their successors, Oleg Kononenko of Russia, Anne McClain of the United States and David Saint-Jacques of Canada arrived in early December and are expected to stay on the ISS for six and a half months.

They were transported by the Soyuz MS-11 spacecraft, which was launched on Dec. 3. The flight was carried out after a spacecraft lift-off failure in October.

On Oct. 11 the capsule of the Soyuz MS-10 spacecraft with Russian cosmonaut Alexei Ovchinin and U.S. astronaut Nick Hague on board made an emergency landing in Kazakhstan after the carrier rocket malfunctioned shortly after lift-off.

Russia then suspended manned space missions but sent a cargo ship to the ISS on Nov. 16. The Progress MS-10 cargo ship carried about 2.5 tons of various supplies, including fuel, air, water, scientific equipment, and life-support equipment for the ISS crew.

Russian state space corporation Roscosmos and investigators need for probe into the microfracture found on the orbital module of the Soyuz MS-09 spacecraft in late August, said the Russian mission control center.

On Dec. 12, a spacewalk was conducted by Russian cosmonauts to check the crack that led to a pressure leak at ISS. Russia's Soyuz models are currently the only spacecraft for spaceflights between the ISS and the Earth.</s>A Soyuz spacecraft ferrying German Alexander Gerst of the European Space Agency, NASA's Serena Aunon-Chancellor from the U.S. and Russian Sergey Prokopyev of Roscosmos landed safely in Kazakhstan, Russia's space agency said.

"There's been a landing... The crew of the manned Soyuz MS-09 has returned safely to Earth after 197 days," Roscosmos said on Twitter.

The spacecraft landed slightly ahead of schedule at 8:02 Moscow time (6:02 am CET), Roscosmos said on its website.

"The crew feels well after returning to Earth," the space agency said.

Live footage on the websites of NASA and Roscosmos did not show the landing of the astronauts' capsule due to thick fog over the snow-covered Kazakh steppe.

Rescuers pulled the crew members out of the capsule, with Prokopyev and Aunon-Chancellor appearing pale and weak due to the effects of long weightlessness, while Gerst beamed broadly and gave an interview to German television.

When the astronauts blasted off in June, they were one of the least experienced crews ever to join the International Space Station - only Gerst had been on a space mission before, in 2014.

Gerst, 42, has now spent a total of 363 days on the ISS, a record for the European Space Agency. He is now flying to Cologne to spend the holidays with his family until December 27th, the ESA said.

"Yes, he has holidays off, only sports and training for regeneration and rehabilitation must be done," a spokesman for the European Astronaut Centre in Cologne told DPA. Gerst, who is known as "Astro Alex" in the German media, tweeted a thanks to those who had helped him on the Horizons mission on Monday before landing.

Thanks to all of you who accompanied me on the #Horizons mission, to let me be your eye in the sky / Vielen Dank an alle, die mich auf der #Horizons Mission begleitet haben, um ihre Welt durch meine Augen zu sehen. Hi-Res: https://t.co/b7I59tQwg5 pic.twitter.com/aDMGq3CSA3

Gerst is expected to land at the Cologne/Bonn airport at 8:45 p.m. on Thursday. After that, he will be taken to a medical research facility of the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt or DLR) in Cologne. His hometown Künzelsau is planning a big celebration in honour for him next summer.

The mission, however, carried great challenges. The first significant incident in the crew's mission came in August when astronauts detected an air leak in their Soyuz spacecraft, which was docked to the orbiting space laboratory.

They sealed the small hole successfully but Russia launched an investigation and its space chief Dmitry Rogozin suggested it could have been deliberate sabotage carried out in space.

Rogozin said that investigators ruled out the possibility the defect was introduced during the spacecraft's manufacture.

Prokopyev and fellow Russian Oleg Kononenko last week carried out a gruelling space walk lasting almost eight hours to locate the hole from the outside and record and bag evidence.

The hole was in a section of the astronauts' spacecraft that was to fall away and burn up in the atmosphere as they landed, hence the need to carry out the probe in space.

During the space walk, Kononenko said there was some kind of black and yellow "furry" deposit that looked like a "spider" around the hole, but no conclusion has been made public.

Prokopyev brought back the evidence to Earth and will hand it to the FSB security service which will carry out laboratory analysis, TASS state news agency reported citing a source.

Their landing back on Earth was originally planned for December 13 but the schedule was put back after the October failure of a Soyuz rocket carrying the next crew -- the first such aborted launch in the post-Soviet era.

Russia's Aleksey Ovchinin and US astronaut Nick Hague took off for the ISS on October 11th but their Soyuz rocket failed minutes after blast-off, forcing them to eject and make a harrowing emergency landing.

At the time Gerst wrote on Twitter that the astronauts' survival showed "what an amazing vehicle" the Soyuz rocket is.

"Spaceflight is hard. And we must keep trying for the benefit of humankind," he wrote.

The first successful launch of astronauts since the October accident took place on December 3, carrying Kononenko, Anne McClain of NASA and David Saint-Jacques of the Canadian Space Agency.</s>NASA astronaut Serena Auñón-Chancellor is carried to a medical tent shortly after she, Germany’s Alexander Gerst and Russia’s Sergey Prokopyev landed in their Soyuz MS-09 spacecraft near the town of Zhezkazgan in Kazakhstan. (NASA Photo / Bill Ingalls)

A Russian Soyuz spaceship that stirred up an international fuss over a drill hole and an air leak brought three spacefliers back to Earth from the International Space Station without a problem.

NASA’s Serena Auñón-Chancellor, Germany’s Alexander Gerst and Russia’s Sergey Prokopyev touched down in the snowy steppes of Kazakhstan at 11:02 a.m. local time Dec. 20 (9:02 p.m. PT Dec. 19), leaving three crewmates on the orbital outpost.

The homeward-bound trio rode the same Soyuz they took up to the station in June. It’s the same Soyuz that experienced an air leak in August, causing consternation in space as well as back down on Earth.

Station crew members quickly traced the leak to a hole that was apparently drilled in a hidden corner of the Soyuz’s habitation module. The hole was plugged with a makeshift patch of epoxy sealant and gauze, leaving investigators at Russia’s Roscosmos space agency to figure out the cause of the breach.

For a time, there was dark talk about potential sabotage, but the current leading hypothesis is that the hole was accidentally drilled into the Soyuz’s hull during assembly, and plugged up to cover the flaw. The plug might have been jarred loose while it was attached to the station, setting off the leak.

The exterior side of the leak site was examined last week during a spacewalk that featured Russian cosmonauts carving away at layers of the Soyuz craft’s shielding and insulation.

Fortunately, the Soyuz crew rode down to Earth in the spacecraft’s sealed-off descent module. The carved-up habitation module was jettisoned along with the Soyuz’s propulsion module before atmospheric re-entry.

All three of the returning spacefliers seemed to be in good spirits as they were helped out of the Soyuz and carried over to easy chairs for their initial medical checks, in accordance with Russian tradition. Auñón-Chancellor grinned and flashed the thumbs-up sign as she was tended to by the recovery team.

The station is now in the care of Russian commander Oleg Kononenko, Canada’s David Saint-Jacques and NASA’s Anne McClain. Meanwhile, on Earth, Russian investigators will check photos and samples from the now-spent spacecraft and try to close the case of the sullied Soyuz.
• An international trio heads for the space station after picture-perfect Soyuz launch
• Russians trace Soyuz rocket failure to a bent sensor; next crew to launch Dec. 3
• U.S.-Russian trio returns to Earth from space station on Sputnik anniversary
• Russian spacewalkers carve away at Soyuz spaceship to inspect plugged hole</s>Ground personnel help International Space Station (ISS) crew member Alexander Gerst of Germany to get out of the Soyuz MS-09 capsule after landing in a remote area near the town of Zhezkazgan, formerly known as Dzhezkazgan, Kazakhstan December 20, 2018. REUTERS/Shamil Zhumatov

(Reuters) - Three members of the International Space Station's crew returned safely to Earth on Thursday, landing in Kazakhstan on a Russian Soyuz craft, NASA reported.

It was the first return from the space station since October, when U.S. astronaut Nick Hague and Russian cosmonaut Alexey Ovchinin landed unharmed on the Kazakh steppe after their rocket bound for the station failed two minutes after liftoff.

NASA astronaut Serena Auñón-Chancellor landed along with her German crewmate Alexander Gerst of the European Space Agency (ESA) and Russian cosmonaut Sergey Prokopyev at 12:02 a.m. EST (11:02 a.m. local time, 0502 GMT), NASA said in a blog post.

Auñón-Chancellor had been in space for 197 days and contributed to hundreds of scientific experiments aboard the orbiting space station.

NASA has relied on Russian rockets to ferry astronauts to the space station since the United States retired its Space Shuttle program in 2011, though the agency has announced plans for test flights carrying two astronauts on commercial rockets made by Boeing and SpaceX next April.

The crew were reported to be in good condition and Auñón-Chancellor is expected to return home to Houston following medical checks, NASA said.

The October accident was the first serious launch problem experienced by a crewed Soyuz space mission since 1983, when a crew narrowly escaped before a launchpad explosion.

Three crew remain on the station: NASA's Anne McClain, David Saint-Jacques of the Canadian Space Agency and Russia's Oleg Kononenko. Three additional crew will join them in February.</s>If you would like to see more articles like this please support our coverage of the space program by becoming a Spaceflight Now Member . If everyone who enjoys our website helps fund it, we can expand and improve our coverage further.

Armed with a knife, scissors and other cutting tools, cosmonauts Oleg Kononenko and Sergey Prokopyev went outside the International Space Station on Dec. 11 to slice into the thermal insulation of a Soyuz spaceship and inspect the site of a repaired air leak that briefly caused a minor drop in air pressure in the research outpost earlier this year.

Kononenko and Prokopyev’s dramatic spacewalk produced unforgettable imagery of the duo vigorously cutting into the Soyuz MS-09 spacecraft’s black insulation, then into an orbital debris shield to inspect the site of a tiny 2-millimeter drill hole plugged in August with an improvised stopper of gauze and epoxy sealant. The spacewalkers worked on the Soyuz spacecraft as it was docked with the space station’s Rassvet module.

The hole is on the orbital module of the Soyuz spacecraft, which is discarded before re-entry into the atmosphere.

These photos taken by European Space Agency astronaut Alexander Gerst show the Russian cosmonauts working on the Soyuz MS-09 spacecraft.

Gerst, Prokopyev and NASA astronaut Serena Auñón-Chancellor are set to ride the Soyuz MS-09 spacecraft back to Earth for a landing Thursday, Dec. 19. But they will come home inside the craft’s landing section, which carries a heat shield to protect the crew during re-entry. The leak in the Soyuz habitation module does not pose a threat to the crew during the descent back into the atmosphere.

Read our full story on the Dec. 11 spacewalk for details.
Soyuz MS-09 lands safely on the steppe in Kazakhstan.