NASA’s Voyager 2 spent the better part of the last 40 years making its way through the heliosphere to become the second human-made object in history to enter interstellar space, the government agency announced Monday. The probe crossed the outer edge of the heliosphere, also known as the heliopause, which acts as a transition zone to interstellar space, on November 5. It’s now about 11 billion miles from Earth.
Voyager 1 managed the same feat in 2012, but its instrument to detect plasma particles had been busted some time during its travel in the 1980s. Voyager 2, on the other hand, has been able to beam back the plasma data from its journey through the heliopause, displaying the interactions between solar and interstellar winds that its predecessor couldn’t.
Both probes launched in 1977, but Voyager 2, which launched first, is considered NASA’s longest-running mission. “Our studies start at the Sun and extend out to everything the solar wind touches. To have the Voyagers sending back information about the edge of the Sun’s influence gives us an unprecedented glimpse of truly uncharted territory,” said Nicola Fox, director of the heliophysics division at NASA, in a news release.
However, Voyager 2 is still well within the solar system and would require another 300 years to reach the inner boundary of the Oort Cloud that currently defines the edge of the solar system, NASA said.
“I think we’re all happy and relieved that the Voyager probes have both operated long enough to make it past this milestone,” said Suzanne Dodd, Voyager project manager at NASA’s Jet Propulsion Laboratory. “This is what we've all been waiting for. Now we’re looking forward to what we’ll be able to learn from having both probes outside the heliopause.”
Cover image: An annotated image showing the various parts and instruments of NASA's Voyager space probe design. Voyager 1 and its identical sister craft Voyager 2 were launched in 1977 to to study the outer Solar System and eventually interstellar space. (Photo by NASA/Hulton Archive/Getty Images)