Endeavour's astronauts accomplished the No. 1 objective of their mission today, installing a $2 billion cosmic ray detector on the International Space Station to scan the invisible universe for years to come. The instrument, which has a 3-foot magnet ring at its core, is the most expensive piece of equipment at the space station and certainly the most prominent scientific device. It will search for antimatter and dark matter for the rest of the life of the station, and hopefully help explain how the cosmos originated.
The astronauts used a pair of robotic arms to remove the Alpha Magnetic Spectrometer from the shuttle, then hoist it onto the sprawling framework on the right side of the station. It marked the grand finale for America's role in the construction of the orbiting outpost, which began 13 years ago. Shuttle commander Mark Kelly, whose wife, Rep. Gabrielle Giffords, had surgery to repair her skull yesterday, said he held his breath as the spectrometer was latched down. "It's a $2 billion cosmic particle detector, it's got 600 physicists that have been working on it ... and it was all in the hands of four of my crew members," Kelly said. He told his crew, "Isn't it a relief that it's no longer our responsibility, that we safely got it installed?" (Read more Mark Kelly stories.)