NASA’s space shuttle program is winding down. With only about half a dozen more flights, shuttle crews will put the finishing touches on the International Space Station (ISS), bringing to an end twelve years of unprecedented orbital construction. An act of Congress in 2008 added another flight to the schedule near the end of the program. Currently scheduled for 2010, this extra flight of the shuttle is going to launch a hunt for antimatter galaxies.

The device that does the actual hunting is called the Alpha Magnetic Spectrometer—or AMS for short. It’s a $1.5 billion cosmic ray detector that the shuttle will deliver to the ISS.

In addition to sensing distant galaxies made entirely of antimatter, the AMS will also test leading theories of dark matter, an invisible and mysterious substance that comprises 83 percent of the matter in the universe. And it will search for strangelets, a theoretical form of matter that’s ultra-massive because it contains so-called strange quarks. Better understanding of strangelets will help scientists to study microquasars and tiny, primordial black holes as they evaporate, thus proving whether these small black holes even exist.

All of these exotic phenomena can make their presence known by the ultra-high energy cosmic rays they emit—the type of particles AMS excels in detecting.

“For the first time, AMS will measure very high-energy cosmic rays very accurately,” explains Nobel laureate Samuel Ting.

Antimatter galaxies, dark matter, strangelets—these are just the phenomena that scientists already know about. If history is any guide, the most exciting discoveries will be things that nobody has ever imagined. Just as radio telescopes and infrared telescopes once revealed cosmic phenomena that had been invisible to traditional optical telescopes, AMS will open up another facet of the cosmos for exploration.

“We will be exploring whole new territories,” Ting says. “The possibility for discovery is off the charts.” … “For the first time we could find out what dark matter is made of.”

This is huge. Anti-matter is a tricky thing; when it hits its counterpart in regular matter, they two annihilate (never to be seen again).

An antihydrogen atom is made from a negatively charged antiproton and a positively charged positron, the antimatter counterpart of the electron. The objective — both for ALPHA and for a competing CERN experiment called ATRAP — is to compare the energy levels in antihydrogen with those of hydrogen, to confirm that antimatter particles experience the same electromagnetic forces as matter particles, a key premise of the standard model. “The goal is to study antihydrogen and you can’t do it without trapping it,” says Cliff Surko, an antimatter researcher at the University of California, San Diego. “This is really a big deal.”