The eight solar panels up there now are 12 to 20 years old — most of them past their design lifetime and deteriorating. Each panel is 112 feet (34 meters) long by 39 feet (12 meters) wide.

The goal of the excursion was to install the second of two ISS Roll-Out Solar Array blankets — IROSAs — that were carried to the space station aboard a SpaceX Dragon cargo ship on Nov. 22.