In Search of Antimatter Galaxies

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. The icon and workhorse of the American space program will have finished its Great Task.
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.
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.
Another mystery that AMS will help solve is the nature of dark matter. Scientists know that the vast majority of the universe is actually made of unseen dark matter rather than ordinary matter. They just don't know what dark matter is. A leading theory is that dark matter is made of a particle called the neutralino. Collisions between neutralinos should produce a large number of high-energy positrons, so AMS could prove whether dark matter is made of neutralinos by looking for this excess of energetic positrons.
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