The Voyager 1 space probe has merged into a newly discovered zone at the solar system’s edge, and scientists think the craft’s next destination could be interstellar space. Measurements from Voyager’s erratic transition, presented at a meeting in December (SN: 1/12/13, p. 17) and in the June 27 Science, reveal that the probe no longer encounters particles emanating from the sun. But Voyager 1 still feels the effects of the sun’s spiral magnetic field. Voyager team scientists think this realm could represent the last leg of Voyager’s journey out of the solar system.
A change in the orientation of the magnetic field will likely herald the probe’s entry into interstellar space. When this will happen “is anybody’s guess,” says Leonard Burlaga, a Voyager team member at NASA’s Goddard Space Flight Center in Greenbelt, Md. But the timing of another Voyager milestone is certain: The plutonium that powers the spacecraft’s instruments will run out in 2020. The team hopes the probe will escape the solar system before then, Burlaga says. “We’re looking forward to seeing that interstellar medium.”