Voyager Set To Enter The Milky Way Presented by Science at NASA More than 30 years after they left Earth, NASA's twin Voyager probes are now at the edge of the solar system. Not only that, they're still working. And with each passing day they are beaming back a message that to scientists is both unsettling and thrilling. messages, expect the unexpected. Its uncanny says Ed Stone of JPL, Voyager Project Scientist since 1972, Voyager 1 and 2 seemed to have a neck for making discoveries. On April 28, 2011, NASA held a press conference to reflect on what the Voyager mission has accomplished, and to preview what lies ahead as the probes prepare to enter the realm of the Milky Way itself. The Voyager adventure began in the late 1970s and 80s when the probes took a grand tour of the outer planets. Voyager 1 visited Jupiter and Saturn, while Voyager 2 flew past Jupiter, Saturn, Uranus, and Neptune. Voyager 2 is still the only probe to visit Uranus and Neptune. When pressed to name the top discoveries from those encounters, Stone pauses, not for lack of material, but rather an embarrassment of riches. It's so hard to choose, he says. There was the discovery of volcanoes on Jupiter's moon, Io, evidence for an underground ocean on Europa, hints of methane rain on Saturn's moon, Titan, the crazily-tipped magnetic poles of Uranus and Neptune, planetary winds that blow faster and faster with increasing distance from the Sun. Each of these discoveries changed the way we thought of other worlds, so stone. In 1980, Voyager 1 used the gravity of Saturn to fling itself, slingshot style out of the plane of the solar system. In 1989, Voyager 2 got a similar assist from Neptune. Both probes set sail into the void. Sailing into the void sounds like a quiet time, but the discoveries have continued. Jupiter 1 and 2 are now at the edge of the solar system in a place called the Heliosheath, where the solar wind meets interstellar gas for the first time. This is a very strange place, filled with a magnetic froth no spacecraft has ever encountered before. Echoing with low frequency radio bursts heard only in the outer reaches of the solar system, so far from home that the Sun is a mere pin prick of light. In many ways, the Heliosheath is not like our models predicted, so stone. Soon, in a matter of years, the two probes will leave the solar system altogether and enter the realm of the stars, interstellar space, the Milky Way itself. Then, they will have a new job, Ambassador. Each probe is famously equipped with a golden record, literally a gold-coded copper phonograph record. It contains more than 100 photographs of Earth, 90 minutes at the world's greatest music, an audio essay entitled Sounds of Earth, featuring everything from burbling mudpots, barking dogs, and roaring Saturn V liftoff. Greetings in 60 human languages, and one whale language, and the brainwaves of a young woman in love. The team led by Carl Sagan assembled the record as a message to possible extraterrestrial civilizations that might encounter the spacecraft. Some people say that the chance of aliens finding the golden record is fantastically remote. The Voyager probes won't come within a few light years of another star for some 40,000 years. What are the odds of making contact under such circumstances? On the other hand, what are the odds of a race of primates evolving to sentience, developing spaceflight, and sending the sound of parking dogs into the cosmos? Expect the unexpected indeed. For more information about Voyager and other mind-blowing NASA missions, please visit science.nasa.gov.