A pair of Russian cosmonauts completed a spacewalk to replace science experiments and remove unnecessary antennas outside the International Space Station yesterday, the last spacewalk in 2014 as NASA prepares for a series of spacewalks to get ISS ready for commercial space taxis.

It took just three and a half hours for station commander Maxim Suraev and flight engineer Alexander Samokutyaev to jettison the “Radiometriya” science experiment, according to Reuters. The device had been tracking seismic activity on earth for the last three years. The cosmonauts also removed a protective cover for an experiment that exposed various forms of life — seeds, bacteria, and ferns — to the space environment.

The two obsolete antennas the cosmonauts jettisoned were from the Poisk mini-research module and were used to guide spacecraft to docking ports on the ISS. Those antennas will continue orbiting the earth for up to a year until the gravitational pull brings them into the atmosphere, where they will burn up.

It was the second spacewalk for both cosmonauts, who spent their time cutting cables and removing bolts. The spacewalk had originally been planned to last six hours. It began at 9:28 a.m. EDT.

It was also the third spacewalk in the last three weeks, and the seventh and last scheduled for this year. NASA has 10 spacewalks planned for next year, which will focus on making the station ready for commercial space taxis by 2017.

NASA tapped Boeing and SpaceX to develop commercial crew vehicles under the Commercial Crew Transportation Capability (CCtCap) contracts awarded in September. The goal is to field private space taxis that can launch American astronauts to the ISS, which would be the first launch from American soil since 2011.

A total of 15 nations own the space station, which cost $100 billion and is currently orbiting the earth 260 miles above the surface.