This past October, NASA announced that after 36 years of flight, Voyager 1 had finally crossed into the interstellar medium that fills the space between the stars. Although it is the first probe to do so, Voyager 1 is not alone in its one-way mission out of the solar system: Four other probes are following it. The destinations of Voyager 1 and 2 and Pioneer 10 and 11 are plotted below. The ultimate destination of the fifth probe—the New Horizons mission to Pluto—is still unknown (its trajectory will be adjusted during its mission in hopes of sending it past another Kuiper Belt object). Although these probes will be dead metal when they reach the stars, all but New Horizons have messages on board designed to be decoded by aliens—just in case.
Voyager 2: Sirius In about 40 000 years, Voyager 2 will zoom by Ross 248, a dim red dwarf about 10 light-years from the sun. After another 256 000 years, Voyager 2’s wanderings will take it in the direction of the brightest star in our sky: Sirius, currently 8.6 light-years away.
Pioneer 10: Aldebaran Pioneer 10, the first probe to visit Jupiter, is now headed in the direction of Aldebaran, a red giant 44 times the diameter of the sun and 68 light-years distant. The probe’s closest approach will be in about 2 million years.
Pioneer 11: Lambda Aquilae Three times the mass of the sun and 55 times as bright, Lambda Aquilae is a young star, only 160 million years old. It will take 4 million years for Pioneer 11 to drift into Lambda Aquilae’s neighborhood, 125 light-years away.
This article originally appeared in print as “The Stars Their Destination.”