Originally Published: 21 JUL 22 04:36 ET

Updated: 21 JUL 22 13:17 ET

By Jackie Wattles, CNN Business

(CNN) -- Two astronauts — one European and one Russian — exited the airlock on the International Space Station for a spacewalk on Thursday, marking the first time in more than 20 years such a joint endeavor has taken place.

Samantha Cristoforetti, an Italian astronaut with the European Space Agency, and Russian cosmonaut Oleg Artemyev entered the vacuum of space in their puffy white spacesuits before 11 a.m. ET, and they're expected to spend about seven hours working to install a 36-foot-long robotic arm on one of the space station's modules.

Spacewalks are a routine endeavor on the ISS, but they typically involve two Americans or Europeans, an American and a European, or two Russians working together. The last time a European astronaut and a Russian cosmonaut left the ISS together wearing Russian-made Orlan spacesuits was in April of 1999, according to NASA. (An American and a Russian also did a joint spacewalk in 2009.)

Thursday's spacewalk is Cristoforetti's first and Artemyev's sixth. Their joint venture comes as tensions on Earth between Russia and the United States and its allies have hit a fever pitch amid the Ukrainian war, though NASA has repeatedly said the conflict has not affected cooperation in space.

This marks the third spacewalk that ISS astronauts have conducted to work on the installation of the European Robotic Arm, which will be able to move objects in and out of the space station for maintenance and even inspect the space station's exterior using built-in cameras. The arm — which will be the third robotic limb attached to the ISS and the only capable of reaching the Russian-controlled portion of the space station — is being affixed to the outside of the new Russian space station module, called Nauka.

Artemyev and Cristoforetti kicked off their spacewalk Thursday by deploying "ten nanosatellites designed to collect radio electronics data." Since the space station is already traveling at orbital speeds, deploying satellites is as easy as tossing them in one direction or another.

The spacewalk is the sixth carried out at the ISS so far in 2022 and the 251st overall. Astronauts routinely leave the station to maintain its exterior, install new hardware or conduct science experiments.

ESA is livestreaming the spacewalk on ESA Web TV on Thursday. Viewers can spot Cristoforetti by the blue stripes on her spacesuit, while Artemyev is wearing red stripes.