The redesign delayed the launch by several months, and the Giffords shooting prompted speculation that Kelly would give up the commander’s chair and force NASA to choose a backup. In February, though, Kelly said he would fly the mission.
If Endeavour launches Friday as planned, on Monday astronauts will use the shuttle’s robotic arm to pluck the ring-shaped detector from the craft’s cargo bay. In a delicate three- to four-hour maneuver involving four astronauts on the shuttle and the station, the shuttle’s robotic arm will hand the AMS to the station’s robotic arm, which will then perch the device atop a space-station truss.
There, the experiment will silently sift space for high-energy particles that Ting and his supporters say will provide clues about some of the universe’s deepest mysteries.
Chief among them: What happened to the antimatter that prevailing theories say the big bang was supposed to create. The big-bang theory of cosmic creation sketches an explosion that was supposed to create equal amounts of matter and its strange twin, antimatter. But no evidence of this primordial antimatter has been detected. So Ting designed the AMS to find antimatter from distant, theoretical “anti-stars” and “anti-galaxies.”
As these theoretical particles fly through the detector’s magnet, their paths will bend in the opposite direction of normal matter.
However, many physicists say that other experiments have ruled out the existence of exotic antimatter stars or galaxies. “I doubt it’s going to see any fundamental antimatter,” said Lawrence M. Krauss, an experimental physicist at Arizona State University.
Krauss and others are more hopeful that the experiment will catch a whiff of another elusive substance: dark matter. The fundamental nature of this weird stuff is unknown, although experiments have shown that it makes up about 23 percent of the mass of the universe. Without it, the Milky Way would fly apart. Theoretical collisions of dark matter should produce positrons — the inverted, positively charged twins of electrons. The AMS is designed to sense such particles.
Two independent teams will sift the AMS data for signals of antimatter and positrons. “If we make a mistake, it will feed critics for a very long time,” Ting said.