Flight Engineers Dmitry Kondratyev and Oleg Skripochka re-entered and closed the hatch on the Pirs airlock, concluding Russia’s 28th spacewalk from the International Space Station. The 4-hour, 51-minute spacewalk ended at 1:21 p.m. EST.

The spacewalking duo installed a pair of experiments outside the station’s Russian segment. The Molniya-Gamma experiment will observe radiation emitted during Earth-bound lightning and thunderstorms. The second experiment, Radiometria, will collect seismic information to better predict earthquakes.