"Voyager’s Race to Interstellar Space"
Ed Stone
Caltech

Abstract

Launched in 1977, two Voyager spacecraft are now exploring the outer reaches of the solar system and beyond.  A supersonic wind from the Sun creates a bubble in the local interstellar medium called the heliosphere.  Different observations suggest that a termination shock forms at 90 to 100 AU from the Sun where the solar wind abruptly slows as it approaches the heliopause, the boundary of the heliosphere.  Voyager 1 is at 88 AU, and recent observations suggest that the shock, which accelerates cosmic rays, is not far beyond.  Once beyond the shock, Voyager 1 will race to reach interstellar space while still transmitting data back to Earth.