The AMS is a state-of-the-art particle physics detector located on the outside of the ISS, and constructed, tested, and operated by an international team of scientists.
The $1.6 billion Alpha Magnetic Spectrometer, or AMS, is located on the outside of the International Space Station.
The AMS studies cosmic rays, or high-energy particles, before they enter Earth's atmosphere.
Based on the last year and half of measurements from the AMS, scientists believe that an observed excess of antimatter particles, or positrons, in the flux of incoming cosmic rays could be "produced when two particles of dark matter collide and annihilate," CERN wrote in a statement released on Wednesday.
This theory, known as supersymmetry, was suggested about two decades ago, but remains to be proven.
Dark matter accounts for more than quarter of the universe’s mass-energy balance, but still hasn't been directly detected. It continues to be one of the greatest mysteries in physics today.
"These results are consistent with the positrons originating from the annihilation of dark matter particles in space, but not yet sufficiently conclusive to rule out other explanations," CERN said.
Alternatively, the positrons could originate from pulsars, or what remains when a star collapses. Pulsars spew out charged particles as they whip around.
Supersymmetry theories also predict a decrease in positron emissions at energies higher than 250 billion electron volts, but that drop-off wasn't detected, CERN said. This may be because the observations have not been fully analyzed yet.
"What we have shown today only represents less than 10 percent of the data," MIT astrophysicist Samuel Ting said in a news conference held by NASA. But in time, "there's no question we are going to solve this problem," he added.
AMS will remain on the ISS for the rest of the space station's lifetime. Statistics gathered in the future will help physicists learn more about the nature of the antimatter excess, Ting said.
The results will be published in the journal Physical Review Letters.