Image: NASA Astronaut Tim Kopra on Dec. 21 spacewalk

Expedition 46 Flight Engineer Tim Kopra on a Dec. 21, 2015 spacewalk, in which Kopra and Expedition 46 Commander Scott Kelly successfully moved the International Space Station's mobile transporter rail car ahead of Wednesday's docking of a Russian cargo supply spacecraft.

After quickly completing their primary objective for the spacewalk, Kelly and Kopra tackled several additional "get-ahead" tasks. Kelly routed a second pair of cables in preparation for International Docking Adapter installment work to support U.S. commercial crew vehicles.

Kopra routed an Ethernet cable that ultimately will connect to a Russian laboratory module. They also retrieved tools that had been in a toolbox on the outside of the station, so they can be used for future work.

The three-hour and 16-minute spacewalk was the second for Kopra, who arrived to the station on Dec. 15, and the third for Kelly, who is nine months into a yearlong mission.