The astronaut Matthias Maurer was the fourth German in space history to leave the ISS space station for an external mission.

After around seven hours in the open cosmos, the Saarlander climbed back into the outpost of humanity on Wednesday together with his US colleague Raja Chari, as shown by live images from the US space agency Nasa.

US astronauts Kayla Barron, Thomas Marshburn and Mark Vande Hei helped the two.

After boarding, while still in his space suit, Maurer jubilantly stretched his arms in the air, although there had been complications.

The two astronauts got out to attach new hoses to a cooling system, replace a camera and set up power and data connections on the external European research platform "Bartolomeo".

"We admire your tenacity and thank you for your work," said the control center at the end of the operation.

Maurer and Chari thanked their colleagues for their support.

"In good health" and "not in danger"

Maurer had to contend with several minor problems during his assignment: First, a loose camera on his helmet, which was then provisionally fixed with wire, temporarily delayed the work.

After that, he became tangled in his tethers, but was able to free himself with the help of instructions from the control center.

Upon returning, it was eventually discovered that there was some water in his helmet.

Maurer was "in good health" and "not in danger," NASA said.

The incident should be investigated.

For the astronauts from the European space agency Esa, it was the first external mission at around 400 kilometers above the earth.

"Today is the day," tweeted the ESA.

Before the spacewalk, the crew of the space station could be seen helping Maurer and Chari put on their space suits.

Maurer had previously described the field mission as the "big highlight" of his space flight.

During outdoor missions, astronauts experience extreme temperature differences of minus 150 degrees on the night side and plus 120 degrees on the day side of the ISS.

Cooling and heating are in the suit.

In addition, Maurer's US space suit is relatively stiff despite the lower pressure inside - astronauts always have to work against this resistance during external missions.

This makes the mission in the open cosmos even more exhausting.

On November 11, Maurer flew with three colleagues from the US space agency Nasa in a US spacecraft to the ISS, where he is to remain until the end of April.

The 52-year-old is the twelfth German in space and the fourth on the ISS.

His three predecessors on the outpost of mankind had also completed a field mission: Thomas Reiter (2006), Hans Schlegel (2008) and Alexander Gerst (2014).

The field trip took place amid the heightened tensions between Russia and the West over the Ukraine war.

At least for the time being, the US space agency Nasa and the Russian space agency Roskosmos have announced that they will continue to operate the ISS together.

In addition to Maurer and Chari, the Russians Anton Schkaplerow and Pyotr Dubrow and the Americans Vande Hei, Marshburn and Barron are currently on board the ISS.

The three Russians Oleg Artemyev, Denis Matweyev and Sergey Korsakov were also added last week.