Two NASA astronauts have completed the 13th spacewalk at the International Space Station (ISS) this year, the agency said, days after the event was postponed over a debris risk.

Astronauts Thomas Marshburn and Kayla Barron headed outside the space laboratory on Thursday, replacing a faulty antenna and restoring its capability.

"It was awesome!" Barron said after completing her first spacewalk, according to a tweet NASA posted.

The duo also "did some get-ahead tasks for future spacewalks," the US agency said, adding that the astronauts returned to the station after six hours and 32 minutes.

The spacewalk, scheduled to take place on Tuesday, was postponed after NASA received a "debris notification" for the orbital outpost.

In a subsequent statement, the agency said Houston experts were assessing a fresh risk from orbital rocket debris that may pass close to the ISS on Friday.

The International Space Station marked 21 years of continuous human presence this month
The International Space Station marked 21 years of continuous human presence this month NASA via AFP

"Mission Control is working with NASA's international partners to prepare for a possible debris avoidance maneuver," they said.

NASA footage showed Marshburn catching a ride on the robotic arm to move around the ISS before getting to work on the antenna.

The spacewalk was the fifth for the astronaut, a doctor who flew aboard a Space Shuttle in 2009 and a Russian Soyuz spacecraft in a mission from 2012-13.

Barron, who was selected for the NASA astronaut corps in 2017, previously served as a submarine warfare officer for the US Navy.

The pair arrived at the ISS on November 11 aboard SpaceX's Crew Dragon Endurance with NASA's Crew-3 mission for a six-month stay.

The ISS marked 21 years of continuous human presence this month, NASA said on its website.

During that period, they said, it had hosted 249 people from 19 nations who had taken part in thousands of research projects.