Video: Expedition 50 spacewalk highlights

Two astronauts ventured outside the International Space Station Friday for the first of four spacewalks to repair a $2 billion cosmic ray detector, breezing through work to prep the device for invasive surgery to splice in new coolant pumps and extend the instrument’s life probing the composition of the universe.

Two astronauts floated outside the International Space Station early Tuesday and replaced one of the grapple fixtures on the end of the lab’s robot arm, the first of two excursions over the next week to complete a complex overhaul that began with a pair of spacewalks last October.

The flight of Gemini 4 launched today in 1965 for NASA’s first Extra Vehicular Activity spacewalk by Ed White on a four-day orbital mission with commander Jim McDivitt.