Exploring the boundaries of our solar system

In addition to helping enable NASA's new vision of taking humans back to the moon and paving the way to Mars and beyond, two robotic space science missions are preparing to explore the outermost and innermost edges of our solar system.

Serious challenges face human exploration, such as the significant radiation hazards from galactic cosmic rays that originate outside our solar system and from solar energetic particles that originate in the sun's corona. The vast majority of cosmic rays are shielded by the complex interactions between the million-mph ionized gas that flows out from our sun-the solar wind-and the ionized and neutral gases outside our solar system in interstellar space. NASA's recently selected Interstellar Boundary Explorer (IBEX) mission (www.ibex.swri.edu) will take the first images of this distant region, exploring the interstellar boundaries at the edge of our solar system roughly 10 billion mi away. These unique observations will provide critical information to improve our understanding of how this shielding really works and make a first step toward pioneering the galactic frontier.