A gauge on the Voyager home page tracks levels of two of the three key signs scientists believe will appear when the spacecraft leave our solar neighborhood and enter interstellar space.
When the three signs are verified, scientists will know that one of the Voyagers has hurtled beyond the magnetic bubble the sun blows around itself, which is known as the heliosphere.
The gauge, as shown on this artist’s conception of one of the Voyagers, indicates the level of fast-moving charged particles, mainly protons, originating from far outside the heliosphere and the level of slower-moving charged particles, also mainly protons, from inside the heliosphere. If the level of outside particles jumps dramatically and the level of inside particles drops precipitously, and these two levels hold steady, that means one of the spacecraft is closing in on the edge of interstellar space. These data are updated every six hours.
Scientists then need only see a change in the direction of the magnetic field to confirm that the spacecraft has sailed beyond the breath of the solar wind and finally arrived in the vast cosmic ocean between stars.
NASA’s Eyes on the Solar System program, a Web-based, video-game-like tool to journey with NASA’s spacecraft through the solar system, has added a Voyager module that takes viewers along for a ride with Voyager 1 as it explores the outer limits of the heliosphere. Time has been sped up to show one day per second. Rolls and other maneuvers are incorporated into the program, based on actual spacecraft navigation data. The charged particle data are also shown. Visit that module at NASA’s Eyes on the Solar System website.