Spacewalking astronauts cutting into cosmic ray detector

Spacewalking astronauts are back outside working to revitalize a cosmic ray detector at the International Space Station.

Italy’s Luca Parmitano and NASA’s Andrew Morgan will cut into the Alpha Magnetic Spectrometer on Friday. They’ll slice through eight stainless steel tubes, using hardware store-type bolt cutters. That will set the stage to install new coolant pumps during the third spacewalk on Dec. 2. 

RELATED: Boeing's first Starliner crew capsule transported to launch pad at Kennedy Space Center

NASA likens the repair work to heart bypass surgery. At least four spacewalks are needed to fix the $2 billion spectrometer, on the hunt for elusive dark matter and antimatter for 8 ½ years. Without a new cooling system, the experiment — led by a Nobel laureate — would end.

NASA considers these the most complicated spacewalks since the Hubble Space Telescope repair missions a few decades ago.