Thirty years ago, the US launched twin probes towards the outer planets. Taking advantage of the favorable arrangement of Jupiter, Saturn, Uranus and Neptune, the Voyagers swung by the four gas giants over the course of a decade, returning valuable data and beautiful, compelling images of the Big Four.
The Voyagers kept on going, heading for interstellar space. Astronomers told us they would travel for hundreds of thousands of years before reaching another star system, since space is pretty damn big, but that caveat did not prevent some SF writers from using the Voyagers as a plot device.
Thanks to a team led by astronomers Carl Sagan and Frank Drake, each probe carried on its side a metallic phonograph record (with a stylus included, in case alien space scientists had moved onto CDs) containing messages in dozens of Earth languages, photographs, music, tidbits about our biology and relative size, the location of our home world, and so on.
John Carpenter’s movie Starman begins with the launch of the Voyagers and quickly establishes that an alien civilization has intercepted one of the probes, and followed its handy roadmap back to Earth. In the movie, the alien scientist, played by Jeff Bridges, does a decent impression of then-UN Secretary General Kurt Waldheim’s accented greeting in English from the Voyager record.
The rest of the movie dwells on Bridge’s illegal alien status, and government attempts to capture him before he escapes across the “border,” and his relationship with “Jenny Hay Den,” played by Karen Allen.
In 1979, a dozen years after its demise from primetime TV, Star Trek came to the big screen with a somewhat tedious vehicle for Capt. Kirk and Crew. Here the story involves an alien civilization looking for its Creator, the maker of V’ger — a fictional successor to the original Voyagers 1 and 2. Somehow the fictional probe, its programming damaged in transit, fostered a machine-based intelligence dead set on finding Earth and the civilization’s ultimate Beginning.
Fiction aside, the doughty probes have been sending data about the far reaches of the Solar System back home virtually non-stop since their launches. Powered by tiny nuclear-powered electrical supplies, Voyagers 1 and 2 have, as their swan song, the task of probing the edge of the Solar System.
The Sun spews forth a steady stream of high energy particles — the solar wind — which travels far into space beyond its planetary system. The heliosphere is the “egg” in which the Sun and the planets are embedded; the edge of heliosphere is where the solar wind loses its kinetic energy and starts to fall back toward the Sun, like a ball tossed straight up in the air.
Voyager 1 will reach this frontier of interstellar space some 12.4 billion miles from the Sun, while Voyager 2 will cross the boundary of the heliosphere only 10.5 billion miles from the Sun. To space scientists, the data suggest that the heliosphere is really not a sphere after all, but is actually lopsided.
There are different explanations for the anomalous shape. One, favored by the fringy Binary Research Institute, is that the Sun is part of a binary star system, with its companion far enough away to be virtually undetectable by visual observation. Binary systems are extremely common in the universe, so the hypothesis is not far fetched. In fact, assuming that the Sun is a solitary star places it in a very rare class of stars.
The mutual orbital motion of the Sun and its hypothetical companion star would distort the heliosphere, pushing it off-center opposite the direction of motion, according to the BRI.
More conventional wisdom suggests that moving interstellar gases and particles, or an interstellar magnetic field, distort the heliosphere, as the Solar System “leans” into the wind. The Voyagers’ eventual escape through the boundary of the heliosphere will perhaps enable space scientists to learn for the first time something about interstellar space, which may confirm or refute this second explanation.
In the meantime, we can marvel about the longevity of two “droids” that have been operating well past their expected lifetimes, and still providing us with answers and posing new questions. Maybe we should rename them C3PO and R2D2.