University of Montana scientist Dan Reisenfeld helped design one of two primary instruments on the NASA spacecraft Interstellar Boundary Explorer, or IBEX, which will create an all-sky map of the interstellar boundary at the far reaches of our solar system.

Reisenfeld and fellow UM researcher Paul Janzen are part of the core payload team for the spacecraft, which is scheduled to launch Oct. 19.

As our sun rumbles around the galactic core at 486,000 mph, it constantly emits particles called the solar wind. At the edge of the solar system, 100 times farther out than the distance between the sun and the Earth, this wind dies down as it hits the hydrogen and helium gas between stars.

The spacecraft will launch aboard a Pegasus rocket dropped from under the belly of an aircraft flying over the Pacific Ocean near the Marshall Islands. The Pegasus will carry IBEX 130 miles above the Earth, and then a motor will push the probe above low-Earth orbit.

The two primary instruments on the 5-foot-wide spacecraft -- IBEX-Low and IBEX-Hi -- detect a range of energetic neutral atoms that are energized at the boundary of the solar system. Reisenfeld designed a section of IBEX-Hi that ionizes, steers and accelerates the particles to where they can be detected.

Besides answering questions about the size and shape of the bow shock and "heliosheath" surrounding our planetary system, IBEX also may answer questions about how that region protects us from interstellar cosmic rays.

Reisenfeld said these rays are intense radiation that can damage DNA or knock out electrical gear on satellites and other spacecraft. Mainly because of the heliosheath, only about 10 percent of cosmic rays reach the inner solar system. Earth's magnetosphere offers another layer of protection that reduces the radiation further.

Reisenfeld became involved with the IBEX project while working at the Los Alamos National Laboratory in New Mexico.

Reisenfeld came to UM in 2004, remaining heavily involved with NASA projects while teaching courses such as modern physics and quantum mechanics. He intends to watch the launch of IBEX at the Virginia headquarters of Orbital Sciences, the private contractor that designed the rocket that will carry the probe aloft.