Two astronauts with the U.S. space agency, NASA, left the International Space Station (ISS) Thursday to conduct a spacewalk to replace a broken antenna system, two days after the walk was postponed over concerns about space debris.

NASA astronauts Thomas Marshburn and Kayla Barron stepped out of the ISS airlock early Thursday to replace the faulty antenna, used to communicate voice and data to ground control. The operation was expected to last six-and-a-half hours.

The spacewalk had originally been scheduled for Tuesday but was postponed late Monday after NASA said it had received a notification of space debris that it needed to assess. The space agency said once it determined the debris did not pose a risk, the operation was rescheduled for Thursday.

It was not immediately clear whether the debris field that prompted the spacewalk to be postponed was related to a Russian anti-satellite missile test two weeks ago. That event created a debris field that forced ISS crew members to seek shelter in their escape capsules as a precaution.

Source: Voice of America