Video: NASA officials preview space station battery replacement spacewalks

After prepping their patient — a $2 billion cosmic ray detector — during two earlier spacewalks, two space station astronauts ventured back outside for a third outing Monday to carry out what amounted to transplant surgery, installing replacement coolant pumps in a bid to revive the costly instrument and extend its life.

Clad in pressurized spacesuits, two Russian cosmonauts headed outside the International Space Station on Wednesday and hand-released four tiny CubeSats and installed hardware for a German experiment to track animal migration.

In a complex bit of orbital surgery, two spacewalking astronauts cut into a $2 billion cosmic ray detector Friday, venting away life-sustaining carbon dioxide refrigerant and then snipping eight coolant lines the size of soda straws to prepare the high-tech “patient” for a coolant pump transplant.