(Update: Postponed) NASA astronauts prepare for spacewalk to install solar array

Two NASA astronauts are gearing up for a spacewalk on Wednesday, December 21, to install a rollout solar array which will augment power on the International Space Station (ISS).

Expedition 68 Flight Engineers Frank Rubio and Josh Cassada will exit the station's Quest airlock at 7:45 a.m. EST to install an International Space Station Roll-Out Solar Array (iROSA) to increase electrical power generation for the 4A power channel on the station's port truss.

The iROSA arrived at the orbiting laboratory on November 27, following a launch aboard NASA's 26th SpaceX Dragon commercial resupply mission. According to NASA, the iROSAs will increase power generation capability by up to 30%, increasing the station's total available power from 160 kilowatts to up to 215 kilowatts.

The agency will provide live coverage of the spacewalk, which will last about seven hours, on NASA Television, the app, and its website.

An additional spacewalk may be conducted on Tuesday, Dec. 27, if more time is needed to complete the iROSA installation. NASA has planned a total of six excursions for the iROSA installation and Wednesday's spacewalk will be the fourth one.

Update 1

Wednesday's spacewalk to install solar arrays has been postponed due to orbital debris tracking near the station. The ground team stepped into procedures to perform a Pre-Determined Debris Avoidance Maneuver (PDAM), without which, it is predicted that the fragment could pass within less than a quarter mile from the station.

NASA said it will assess the next possible opportunity to perform today's planned spacewalk to install a new set of roll-out solar arrays to augment the station's power capabilities.