The Alpha Magnetic Spectrometer looks for dark matter, antimatter and missing matter from a module on the International Space Station

The Alpha Magnetic Spectrometer (AMS-02) is a particle-physics detector that looks for dark matter, antimatter and missing matter from a module attached to the outside of the International Space Station (ISS). It also performs precision measurements of cosmic rays.

On its final flight on 16 May 2011, space shuttle Endeavour delivered the experiment to the ISS as part of space shuttle mission STS-134. AMS-02 was already sending data back to Earth by 19 May, and a year on some 17 billion cosmic-ray events had been collected. Data are received by NASA, and then relayed to the AMS Payload Operations Control Centre (POCC) at CERN for analysis. The experiment is run by a collaboration of 56 institutions. The detector, which measures 64 cubic metres and weighs 8.5 tonnes, was assembled at CERN.

STS-134 was crewed by commander Mark Kelly, pilot Gregory Johnson, mission specialists Gregory Chamitoff, Michael Fincke, Andrew Feustel and European Space Agency (ESA) astronaut Roberto Vittori. The AMS detector's first year in space was a learning curve: the data were used to calibrate the detector and fully understand its performance in the extreme thermal conditions encountered in space.

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