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a whiff of dark matter on the iss

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presented by science at nasa

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in science fiction movies finding

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antimatter on board your spaceship is

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not good news

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usually it means you're moments away

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from an explosion

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in real life though finding antimatter

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could lead to a nobel prize

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on april 3rd researchers led by nobel

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laureate samuel ting of mit announced

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that the alpha magnetic spectrometer a

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particle detector operating on board the

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international space station since 2011

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has counted more than 400 000 positrons

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the antimatter equivalent of electrons

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there's no danger of an explosion but

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the discovery is sending shock waves

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through the scientific community

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these data show the existence of a new

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physical phenomenon wrote ting and

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colleagues in an article published in

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the physical review letters

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it could be a sign of dark matter

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the alpha magnetic spectrometer ams for

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short was delivered to the iss by the

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space shuttle endeavour on its final

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flight in may 2011.

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in its first 18 months of operations

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from may 19 2011 to december 10 2012

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the ams analyzed 25 billion cosmic ray

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events

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of these an unprecedented number were

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unambiguously identified as positrons

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cosmic rays are subatomic particles such

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as protons and helium nuclei accelerated

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to near light speed by supernova

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explosions and other violent events in

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the cosmos

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researchers have long thought that

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cosmic rays contain a sprinkling of

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antimatter italy's pamela satellite

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detected high-energy positrons in 2009

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and nasa's fermi gamma-ray observatory

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confirmed to the find two years later

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but where do the positrons come from

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the universe is almost completely devoid

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of antimatter so the positron fraction

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of cosmic ray electrons as much as 10

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percent is a little surprising

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one idea is dark matter

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astronomers know that the vast majority

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of the material universe is actually

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made of dark matter rather than ordinary

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matter

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it exerts gravity but emits no light

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which makes it devilishly difficult to

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study

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a leading theory holds that dark matter

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is made of a particle called the

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neutroleno

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produce a large number of high-energy

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positrons which the ams should be able

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to detect with unprecedented

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sensitivity the accuracy of our

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measurements is one percent which is

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excellent and we have statistics

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unmatched by any other spacecraft says

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ting

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so far the evidence supports the

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hypothesis of dark matter

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but he cautions it does not rule out

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another possibility

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pulsars

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stars formed in the aftermath of

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supernova explosions

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they can spin on their axis thousands of

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times a second flinging particles into

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space with fantastic energies that

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accelerators on earth can't match

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among these particles are pairs of

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electrons and positrons

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ams can distinguish between pulsars and

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dark matter but not yet

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we need more data at higher energies to

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decide which is the correct explanation

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says ting

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it is only a matter of time perhaps

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months or a few years

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built by scientists from 16 countries

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with support from the u.s department of

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energy the alpha magnetic spectrometer

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will continue operating for the rest of

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the life of the space station at least

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until 2020

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between now and then the mystery of dark

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matter could be solved once and for all