ISS Spacewalk Set for Tuesday

NASA astronauts Thomas Marshburn and Kayla Barron will perform the repair during the spacewalk, which is expected to last about six hours and 30 minutes. It's the first spacewalk for Astronaut Kayla Barron, as well as Expedition 66, NASA said.

The spacewalk is expected to begin at approximately 7:10 a.m., and may be watched live on NASA TV.

The spacewalk is primarily focused on replacing a failed S-Band antenna subassembly on Port Truss, Dana Weigel, NASA deputy manager of the International Space Station Program, said Monday.

The spare Port 1 Truss S-Band communications antennae is already attached to the side of the ISS.

"This one's got a failed return link, which means we can uplink from the ground to station through that string but we can't get anything back through its downlink," Weigel said. "It hasn't been an impact on operations because we've got a lot of redundancy onboard."

NASA learned about the faulty antenna in September, which allowed astronauts the opportunity to practice the exact spacewalk in a neutral buoyancy laboratory, Vincent LaCourt, NASA spacewalk flight director said.

"We had a conference with them this morning," LaCourt said. "The crew's feeling great. They feel very well prepared, and my ground team is also well prepared."

The spacewalk comes two weeks after a Russian anti-satellite test (ASAT) created a cloud of debris with at least 1,500 trackable pieces, and stoked swift condemnation by U.S. officials.

The potential threat from debris was a concern for NASA officials when planning the spacewalk, Weigel said.

"When the initial breakup occurred, the debris was very concentrated," she said. "Over time it has dispersed."

"As ISS passed through the orbit of the debris, we had a heightened, elevated concern for about 24 hours after the event," she said. "Since that time, the debris has dispersed out quite a bit more. The background environment is slightly elevated. It's about two times what it had been prior to the event for the space station as a whole."

Astronauts conducting the spacewalk face a 7 percent increased risk from debris following the ASAT, Weigel said.

The predicted risk for the spacewalk, however, falls in line with others conducted in past years, she added.

"Unfortunately when you have a debris event like this, and you get a lot of really small pieces scattered around, it just becomes part of the average environment," she said. "[Extravehicular activity] EVA has always been risky, so the 7 percent is a small increase that is well within the flux that we see in the natural environment."