WATCH: Russian Cosmonauts Install Animal Tracking Antenna on ISS

Sergey Prokopyev and Oleg Artemyev successfully ventured outside of the station's Zvezda module to perch the Icarus antenna on the International Space Station as part of a joint experiment with German scientists to track wild animals.

The project aims to study animal behavior by observing migration of small animals around the globe, investigate the spread of diseases and possibly forecast natural disasters.

READ MORE: Russian Cosmonauts Set New Record for Longest Spacewalk (VIDEO)

Near the five-hour mark, spacewalkers Sergey Prokopyev and Oleg Artemyev continued installing the Icarus animal-tracking study (collaboration between @DLR_en and @Roscosmos) outside of the station's Zvezda service module. #AskNASA https://t.co/yuOTrZ4Jut pic.twitter.com/tjWuQN2wmH

— Intl. Space Station (@Space_Station) 15 августа 2018 г.

Russian cosmonauts have returned from a spacewalk after spending 7 hours 46 minutes outside the International Space Station. Sergey Prokopyev and Oleg Artemyev were outside an hour and a half longer than planned after struggling with cables for a bird-tracking antenna, an executive at Russia's Energia rocket-making firm said.

"The delay was primarily due to the cable-laying," Alexander Kaleri told reporters. "There’re already plenty of cables outside."

The spacewalkers also launched four tiny research satellites. The delay did not allow them to fetch two of the four boxes with microbe samples from the ISS hull. Earlier tests showed exposure made some of them more viral and resilient.

​