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Probe to Examine Our Space in Space

Irene Klotz, Discovery News

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With a budget of $169 million, scientists had limited options for launchers. They settled on a low-cost Pegasus booster, an air-launched system created by Orbital Sciences Corp., and outfitted IBEX with a hydrazine-fueled rocket motor that can place it into an orbit that reaches a distance nearly as far from Earth as the moon.

Two-thirds of the 1,000-pound spacecraft is fuel.

"This will be quite a feat," McComas said.

IBEX will take several weeks to maneuver into position before mapping can begin. Each full-sky survey will take six months. IBEX currently is funded for two years.

"We're going to see some things that we don't understand," said IBEX program scientist Eric Christian at NASA headquarters in Washington, D.C.

Among the mission's goals are to determine how the environment may have changed over time. For example, scientists are interested in learning if galactic cosmic rays were more prevalent in the past, as higher bursts of radiation may have impacted evolution.

"We don't know how the interaction works today," Christian said.

NASA's Voyager probes were dispatched in the 1970s to survey the outer planets. Voyager 1 crossed an area known as the termination shock, the boundary region between the solar system and the intergalactic medium in 2004. Voyager 2 followed in 2007.

Both probes are headed toward the outer boundary of the solar system known as the heliopause, which is where the sun's influence ends and interstellar space begins.

So far, scientists have learned that there are cosmic rays being produced from somewhere in the heliosphere that are not coming from nova and supernova explosions and that heliosphere is not uniformly shaped. Voyager 2 hit the termination shock nearly a billion miles sooner than Voyager 1.

"Maybe there's stronger-than expected magnetic fields on the outside pushing (the heliosphere) in on the south side," McComas said. "The whole region may be deflated. Nobody ever thought we could cross that much closer in with Voyager 2."

IBEX's launch is set for Sunday from the Kwajalein Atoll, located on the Marshall Islands in the Pacific Ocean. That location is closer to the equator than mainland U.S. launch sites, which will enable the rocket to take maximum advantage of Earth's rotational spin and leave the satellite in as high an altitude as possible.

Related Links:

Discovery Space

Southwest Research Institute

Interstellar Boundary Explorer, or IBEX