Terry Virts tweeted after completing with his partner astronaut Barry ``Butch'' Wilmore to prepare the International Space Station in development.

U.S. astronaut Terry Virts tweeted his followers this image after completing a series of spacewalks with his partner astronaut Barry "Butch" Wilmore to prepare the International Space Station for upcoming U.S. commercial spacecraft currently in development. Virts commented on the tweet: "Mission Accomplished - 3 #spacewalks, 800' of cable, 4 antennas, 3 laser reflectors, 1 greased robotic arm."