Hubble telescope to scout the Voyagers’ paths through interstellar space
by Jessica Hall
Our Voyager spacecraft are boldly going where no man has gone before. And now, Hubble is scouting their path into space: lighting up the map enough to take some readings, before the spacecraft ever get to where they’re going.
“If the Voyager spacecraft are the Google Street View car going around your neighborhood taking pictures on the street, then Hubble is providing the overview, the road map for the Voyagers on their trip through interstellar space,” elaborates lead author Julia Zachary, an undergraduate student from Wesleyan University.
It’s not about pre-empting the Voyager missions or stealing their thunder. Quite the opposite: Hubble and the Voyagers are joining forces to check one another’s readings and further illuminate our understanding of what’s going on in the liminal regions through which the Voyagers are traveling.
Both Voyager spacecraft were launched in 1977, on missions to visit Jupiter, Saturn, Uranus and Neptune. (My Very Educated Mother Just Served Us Neapolitan Pizza…) Voyager 1 left the heliosphere and entered interstellar space in 2012, and by now it’s more than 20 billion kilometers from Earth. Voyager 2 is moving slower, so it’s still inside the Solar System, but even that slower-moving spacecraft is around 17 billion kilometers away.
Each Voyager is traveling at a different angle away from the plane of the Solar System, and Hubble will peer into space along their line-of-sight paths. By doing some spectroscopy along those lines of sight, Zachary and colleagues were able to tease out details about what lies in the Voyagers’ future. Mostly it’s a lot of vacuum, with some clouds of cold gas. The relative distribution of the clouds and gas and vacuum, though, matters. That’s how we know when the Voyagers leave the sheltering cradle of our heliosphere for the hard vacuum of interstellar space: they take readings on their electromagnetic environments, and at the turbulent edge of the bubble our sun has blown as it ages, things get electromagnetically… interesting. Like, “magnetic bubbles” kind of interesting. This partnership affords an opportunity to look closely at such phenomena by correlating observations between Hubble and the Voyagers.
Even though Voyager 1 has departed the solar system, it still hasn’t made its way through the local interstellar medium, a bubble of material that surrounds the solar system like nesting dolls. The Hubble data suggest that Voyager 2 will exit it in a couple of thousand years. It’s unclear when Voyager 1 will break through the bubble.
Zachary and colleagues reported their findings on January 6 at a meeting of the American Astronomical Society.
(For more on the boundary between our solar system and interstellar space, you really should go read about the heliosphere, because it’s made of brain candy.)
Originally published at www.extremetech.com on January 13, 2017.