A Soyuz space capsule carrying two NASA astronauts and a Russian cosmonaut touched down safely in Kazakhstan on Thursday after a three-hour, 48-minute trip back to Earth from the International Space Station.

Commander Oleg Artemyev, flight engineer Drew Feustel and Ricky Arnold were extracted from the craft almost immediately after landing, smiling but physically weak after 197 days in space

The mission included spacewalks and research but was most notable for a controversial leak that required emergency repairs.

NASA sought on Wednesday to tamp down speculation that sabotage caused a tiny hole found last month in the side of a Russian module docked at the International Space Station, but the mystery remained unsolved.

NASA stressed in a brief statement issued from its Washington headquarters that Dimitry Rogozin, general director of the Russian space agency Roscosmos, had in public comments this week ruled out a manufacturing defect as the cause.

However, NASA added, “This conclusion does not necessarily mean the hole was created intentionally or with mal-intent,” as some media outlets interpreted Rogozin’s remarks as suggesting.

Rather than giving greater credence to foul play, the elimination of a manufacturing defect as causing the hole “indicates that this is an isolated issue which does not categorically affect future production,” NASA said.

Roscosmos and NASA have each opened their own investigations of the 2 millimeter-wide hole detected in late August on the exterior wall of a Russian Soyuz capsule docked to the space station after ground operators reported slight dips in pressure levels.