GENEVA — The first results from a $2 billion instrument aboard the international space station have offered tentative support for the theory that exotic dark matter, invisible but abundant, permeates the universe.
The instrument, the Alpha Magnetic Spectrometer (AMS), has not seen dark matter directly — by definition, the stuff is invisible — and results announced so far do not lend themselves to a slam-dunk conclusion that dark matter is a fact of the cosmos and not merely a theoretical construct.
But the 7.5-ton device, which rides a truss on the space station like a bell on a bicycle's handlebars, has detected hundreds of thousands of particles that have features suggesting that they are debris from collisions of dark matter particles.
"We, of course, have a feeling what is happening," said Nobel-winning physicist Samuel Ting of the Massachusetts Institute of Technology, speaking in a packed auditorium at CERN, the Geneva-based European particle physics laboratory. But Ting, pressed by audience members to reveal more of his data and give a stronger conclusion, stuck to a modulated message.
"It took us 18 years to build this experiment. We want to do it very accurately," he said.
The AMS operates at the nexus of subatomic nature and Big Science. The project's $2 billion cost has been a source of controversy. The detector, funded through an international collaboration, including money from NASA, overcame delays and redesigns and one outright cancellation before riding to orbit in 2011 on the last flight of the space shuttle Endeavour.
The instrument had to be designed to withstand the rigors of space and to operate without the benefit of repair or recalibration. It has functioned splendidly, Ting said. It detects cosmic rays, which are particles moving at extraordinary velocity and coming from all over the galaxy. The AMS sorts through the particles, measuring their momentum and charge.