University of California-Riverside physicist Haruichi Washimi, using a computer model simulation, has predicted when the interplanetary spacecraft will cross the so-called "termination shock" -- a spherical shell around the solar system that marks the point at which the solar wind slows to subsonic speed.

According to Washimi's simulations, the spacecraft will cross the termination shock late this year or early in 2008.

"Washimi's model has predicted the location of a boundary that is approximately 90 times farther from The Sun than is the Earth, to within a few percent," said Gary Zank, director of the Institute of Geophysics and Planetary Physics and one of the co-authors of the research paper. "This is truly remarkable given the enormous complexity of the physics involved, the temporal and spatial scales involved, and the variability of the solar wind conditions."

The complex research is detailed in the Dec. 1 issue of The Astrophysical Journal.