The Voyager Journey to Interstellar Space

Abstract:

Now at 133 AU, Voyager 1 is more than 10 AU beyond the heliopause where the interstellar wind is strongly perturbed as it flows around the heliosphere. Although there is no measurable gradient in the cosmic ray intensity, there have been four extended periods with significant pitch angle anisotropies that may arise from draping of the interstellar magnetic field around the heliopause and from slow pitch angle scattering due to an extremely low level of magnetic turbulence. Plasma oscillations associated with transient variations caused by shocks of solar origin reveal a plasma density that increases with increasing radial distance.

Now at 110 AU, Voyager 2 continues to explore the outer regions of the heliosheath where the solar wind has turned 80 degrees from radial as it flows toward the heliotail. The intensity of galactic cosmic ray helium at Voyager 2 has been increasing and is now 85% of that observed by Voyager 1, suggesting Voyager 2 may reach interstellar space in several years.