GENEVA — A $2 billion cosmic ray detector on the International Space Station has found the footprint of something that could be dark matter, the mysterious substance that is believed to hold the cosmos together but has never been directly observed, scientists say.

But the first results from the Alpha Magnetic Spectrometer, known by its acronym AMS, are almost as enigmatic as dark matter itself. They show evidence of new physics phenomena that could be the strange and unknown dark matter or could be energy that originates from pulsars, scientists at the European particle physics laboratory near Geneva announced Wednesday.

The results from the detector are significant, because dark matter is thought to make up about a quarter of all the matter in the universe. Unraveling the mystery of dark matter could help scientists better understand the composition of our universe and, more particularly, what holds galaxies together.

Nobel-winning physicist Samuel Ting, who leads the team, told colleagues at the European Organization for Nuclear Research, known as CERN, that he expects a more conclusive answer within months about this “unexpected new phenomena.”

The 7-ton detector, which was sent into space two years ago and has a 3-foot (0.91-meter) magnet ring at its core, is transmitting the data to CERN on the Swiss-French border, where it is being analyzed.

The instrument will search for antimatter and dark matter for the rest of the life of the space station — at least until 2020 — transmitting data to an international team of 600 scientists based in Geneva that is led by Ting, a physicist at the Massachusetts Institute of Technology.

The findings Wednesday are based on seeing an excess of positrons — positively charged subatomic particles.

Since the highly accurate AMS magnetic detector began studying cosmic ray particles in space, it has found about 400,000 positrons whose surging energies indicate they might have been created when particles of dark matter collided and destroyed each other.

“It is this level of precision that will allow us to tell whether our current positron observation has a dark matter or pulsar origin,” Ting said.

Other scientists praised the results and looked forward to more.

“This is an 80-year-old detective story and we are getting close to the end,” said University of Chicago physicist Michael Turner, one of the giants in the field of dark matter. “This is a tantalizing clue and further results from AMS could finish the story.”