NASA Primes Spacecraft to Probe Solar System's Fringe

NASA is gearing up to launch a new spacecraft to probe the fringe of the solar system this month where material from the sun hits the cold expanse of space.

The Interstellar Boundary Explorer (IBEX) spacecraft is set to lift off atop an air-launched Pegasus XL rocket Oct. 19 from Kwajalein Atoll, a part of the Marshall Islands in the Pacific Ocean.

While it won't actually travel beyond all the planets to investigate the solar system's far reaches, the coffee table-sized spacecraft must escape the area where Earth's magnetic field reigns, which could interfere with its measurements. The $169 million observatory is due to climb 200,000 miles (322,000 kilometers) above Earth and settle into orbit there for a mission of at least two years. For comparison, the moon orbits about 240,000 miles (385,000 km) from Earth.

"One of [IBEX's] prime goals is to tell us the place of the solar system in the galaxy," said Eric Christian, IBEX program scientist at NASA headquarters in Washington, D.C., during a Monday briefing. "How the solar system moves through the galaxy is scientifically interesting and may be interesting from an evolution-of-Earth standpoint."

The boundary at the solar system's final frontier was first explored by the Voyager 1 spacecraft in 2004, when it encountered an invisible shock created as the charged particles streaming off the sun hit the neutral gas from interstellar space. This so-called termination shock marks the beginning of the edge of the solar system.

The spacecraft will utilize a novel three-stage method to reach its distant orbit around Earth to scan the solar system?s edge. Unlike previous launches of the solid-fueled Pegasus rocket, IBEX will boost itself beyond its initial orbit using an additional solid rocket motor and a hydrazine fuel stage, mission managers said. ?

"IBEX will let us make the first global observations of the region beyond the termination shock at the very edges of our solar system," said David J. McComas, IBEX principal investigator from the Southwest Research Institute (SwRI) in San Antonio, Texas. "This region is critical because it shields out the vast majority of the deadly cosmic rays that would otherwise permeate the space around the Earth and other planets."

IBEX plans to create an all-sky map of the interaction between particles from the solar wind, called the heliosphere, and the material in the galaxy beyond our solar system. Sometimes, when a neutral atom from interstellar space passes a positively-charged particle from the sun, an electron hops from one to the other, making the charged atom neutral. IBEX is designed to detect these fast-moving neutral particles and trace their direction back to the solar system's edge, gradually building up a picture of this chaotic frontier.

"We know that the pictures that IBEX gives us are going to surprise us, and that's one of the fun things about science," Christian said. "This is really exciting, it's really going to increase our knowledge of the heliosphere."

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