ScienceCasts: A Whiff of Dark Matter on the ISS

In astronomy and cosmology, dark matter is a type of matter hypothesized to account for a large part of the total mass in the universe. Dark matter cannot be seen directly with telescopes; evidently it neither emits nor absorbs light or other electromagnetic radiation at any significant level. Instead, its existence and properties are inferred from its gravitational effects on visible matter, radiation, and the large-scale structure of the universe. According to the Planck mission team, and based on the standard model of cosmology, the total mass–energy of the universe contains 4.9% ordinary matter, 26.8% dark matter and 68.3% dark energy. Thus, dark matter is estimated to constitute 84.5% of the total matter in the universe.

On 3 April 2013, NASA scientists reported that hints of dark matter may have been detected by the Alpha Magnetic Spectrometer on the International Space Station. According to the scientists, "The first results from the space-borne Alpha Magnetic Spectrometer confirm an unexplained excess of high-energy positrons in Earth-bound cosmic rays."

font: wikipedia

To know more about dark matter and dark energy follow this link: http://home.web.cern.ch/about/physics/dark-matter

CERN press release:

Geneva 3 April 2013. The international team running the Alpha Magnetic Spectrometer (AMS) today announced the first results in its search for dark matter. The results, presented by AMS spokesperson Professor Samuel Ting (...). They report the observation of an excess of positrons in the cosmic ray flux.

The AMS results are based on some 25 billion recorded events, including 400,000 positrons with energies between 0.5 GeV and 350 GeV, recorded over a year and a half. This represents the largest collection of antimatter particles recorded in space. The positron fraction increases from 10 GeV to 250 GeV, with the data showing the slope of the increase reducing by an order of magnitude over the range 20-250 GeV. The data also show no significant variation over time, or any preferred incoming direction. 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. [...]