Scientists hope to illuminate universe's dark side

April 30, 2011 - 0:0

CAPE CANAVERAL, Florida (Reuters) -- Everything scientists now know about the cosmos, from the Big Bang to black holes, has come from measurements of light rays.

But Mother Nature speaks in particles too, and until now their instruments have been largely deaf to her second tongue.
A device due to launch aboard the space shuttle Endeavour from Florida on Friday is designed to give scientists their first detailed study of the electrically charged particles streaming through the cosmos.
The Alpha Magnetic Spectrometer, or AMS, could reshape modern understandings of the universe, much the same way that the Hubble Space Telescope pioneered new frontiers in astronomy, including the startling discovery that the universe's rate of expansion is speeding up.
“Charged cosmic rays are a nearly unexplored region of science,” said Massachusetts Institute of Technology physicist Samuel Ting, a Nobel laureate who heads the 600-member team that developed the $2 billion AMS.
The pictures painted by AMS, which was assembled at the CERN physics research center near Geneva, could bring to light the universe's so-called dark matter -- material that is so far unaccounted for but necessary to explain what is observable.
Stars, planets, gas, dust and other detectable phenomena account for less than 10 percent of the matter that is believed to exist. Without dark matter or some other phenomenon, the galaxies would be unable to hold themselves together.
Although by definition dark matter cannot be directly detected, studies show colliding dark particles should leave telltale footprints in the form of positrons, a type of normal-matter particle.
Scientists have gotten hints of excess positrons, which could stem from dark matter collisions, from predecessor space-borne instruments. But only AMS, which will be attached to the outside of the International Space Station and operated for as long as the station remains in orbit, will be able to make enough measurements to provide proof.
The devices need to operate in space because Earth's atmosphere shields the planet from cosmic rays, which would be deadly to life.
“Most of the structure of the universe is caused by dark, not ordinary, matter. The seeds for all the galaxies, even our own, come from it,” said Josephy Lykken, a theoretical physicist at the Fermi National Accelerator Laboratory who is not on the AMS team.