Spacewalking astronauts attached new pumps to a cosmic ray detector outside the International Space Station on Monday in a bid to extend its scientific life. It was the third spacewalk in nearly three weeks for Italy’s Luca Parmitano and NASA’s Andrew Morgan. NASA compares this series of four spacewalks — the most complex since the Hubble Space Telescope missions — to heart bypass surgery because they are designed to bypass the old, degraded pumps.
