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 difficult 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.
"We're going to perform what could be considered open heart surgery on this amazing experiment," said Italian astronaut Luca Parmitano, the current space station commander.
The 7.5-ton patient in this case is the Alpha Magnetic Spectrometer, or AMS, the most expensive science instrument aboard the space station and one that was not designed to be serviced in orbit. As such, the "operation" is considered one of the most challenging since work to repair and upgrade the Hubble Space Telescope.
"It's definitely towards the top of the list, if not on the top," said Tara Jochim, the AMS repair manager at the Johnson Space Center in Houston.