In an effort to uncover some of the universe's greatest mysteries, an international team of researchers has developed the largest space-based particle physics detector. Known as the Alpha Magnetic Spectrometer (AMS-02), it will study the universe and its origins by searching for dark matter and antimatter and measuring the composition of cosmic rays with greater precision than any previous device.

"There is nothing else like it," says Trent Martin, NASA's project manager for the detector, which is being built by 56 institutions in 16 countries and sponsored by the U.S. Department of Energy. Head of the AMS-02 collaboration is 1976 Nobel Laureate Samuel Ting, also a professor of physics at MIT. The spectrometer is set to fly to the International Space Station on the final space shuttle mission, scheduled for February. It will be attached to the outside of the space station and gather roughly seven gigabytes of data per second. That data will be sent to a ground station for analysis.

The core of the spectrometer is its doughnut-shaped magnet, one meter in diameter. At its center are eight individual detectors. The magnet pulls particles in, bending them in a direction that corresponds to their charge. The new instruments in the center can then measure different aspects of the particles such as their trajectory, mass, velocity, speed, and energy. AMS-02 also has an "anticounter" that rejects particles that enter at the wrong angle; a star tracker and GPS for accurate position and orientation; and more than 650 microprocessors to transform the signals from the detectors into digital information for ground-based computers to analyze.

The only current space-based experiment along the lines of AMS-02 is Pamela, a cosmic ray and dark matter detector launched by Russia and Italy in 2007. Pamela is much smaller and less sensitive than AMS-02, says Roberto Battiston, a professor of physics at the University of Perugia and the National Institute of Nuclear Physics in Perugia, Italy, and the deputy spokesman for AMS-02. The new spectrometer weighs 7,000 kilograms and is over 4.5 meters wide and equally tall. "It would take Pamela one year to try and detect as much data as the new detector can gather in one to two days," Battiston says.