Antiproton ring found around Earth

Antiprotons found in Earth's radiation belts. [Link]

Piergiorgio Picozza from the University of Rome Tor Vergata, Italy, and colleagues detected the antiprotons using PAMELA, a cosmic-ray detector attached to a Russian Earth-observation satellite. The spacecraft flies through the Earth's inner radiation belt over the south Atlantic.

Between July 2006 and December 2008, PAMELA detected 28 antiprotons trapped in spiralling orbits around the magnetic field lines sprouting from the Earth's south pole (Astrophysical Journal Letters, DOI: 10.1088/2041-8205/737/2/l29). PAMELA samples only a small part of the inner radiation belt, but antiprotons are probably trapped throughout it. "We are talking about of billions of particles," says team member Francesco Cafagna from the University of Bari in Italy.

"I find it very interesting to note that the Earth's magnetic field works a little bit like the magnetic traps that we are using in the lab," says Rolf Landua at the CERN particle physics laboratory near Geneva, Switzerland. There, researchers have been trying to trap antimatter for ever longer periods to compare its behaviour with that of normal matter.

Alessandro Bruno, another team member from Bari, says antimatter in the Earth's radiation belts might one day be useful for fuelling spacecraft. Future rockets could be powered by the reaction between matter and antimatter, a reaction that produces energy even more efficiently than nuclear fusion in the sun's core.

"This is the most abundant source of antiprotons near the Earth," says Bruno. "Who knows, one day a spacecraft could launch then refuel in the inner radiation belt before travelling further."

Millions or billions of times as many antiprotons probably ring the giant planets.