NASA - National Aeronautics and Space Administration

03.23.09

IBEX Uses Particles to Shed Light on the Outer Solar System


This IBEX data image shows a dark sky map with the first orbit's coincidence counts from hydrogen atoms at speeds from about 100,000 to 36 million miles per hour. Image credit: Southwest Research Institute

What do you see when you look at the regions where the sun's influence wanes and interstellar space begins? It depends on how you look.

While many astronomers observe the wonders of the universe through the light that objects emit, some build an image using atomic particles instead.

For the first time, space physicists are building a comprehensive picture of the interactions taking place in the outer solar system—called the interstellar boundary—using particles detected by NASA's Interstellar Boundary Explorer (IBEX). "IBEX is a fantastic mission of exploration and discovery," said David McComas, of the Southwest Research Institute in San Antonio, Texas, who is the principal investigator of the IBEX mission.

The new satellite's mapping mission got under way in December 2007 when IBEX saw "first light," that moment when scientists anxiously point a telescope at its target for the first time and begin collecting photons, radio waves or, in IBEX's case, high-speed atoms.

"Like an optical or radio observatory, where the first 'on target' photons through the focal plane are called 'first light,' we now have the first energetic neutral atoms (ENAs) detected by IBEX's sensors," said Robert MacDowall, IBEX mission scientist at NASA's Goddard Space Flight Center in Greenbelt, Md.

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