NASA’s Voyager team has confirmed that Voyager 2 has become the second spacecraft to exit the Sun’s Heliosphere and enter interstellar space. Voyager 2 joins its counterpart Voyager 1 which entered interstellar space in August 2012.
Voyager 2 was launched atop a Titan IIIE rocket on August 20, 1977, 16 days before Voyager 1. It was designed to last just 5 years and tasked with making close-up studies of Jupiter and Saturn. However, with remote reprogramming, Voyager 2 was given capabilities it didn’t have when it left Earth. The reprogramming allowed researchers to extend its mission to 4 planets and over 41 years of exploration.
“Voyager has a very special place for us in our heliophysics fleet,” said the director of the Heliophysics Division at NASA, Nicola Fox. “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.”
NASA researchers confirmed that Voyager 2 had escaped the Sun’s heliosphere using the spacecraft’s onboard Plasma Science Experiment (PLS).
The heliosphere is a protective bubble of magnetic fields and particles created by the sun. This region of space is filled with plasma flowing out from the sun. This flow is known as solar wind and it creates a “bubble” of plasma around our solar system. The PLS instrument aboard Voyager 2 observed a significant drop off in the amount of plasma in the space surrounding the spacecraft, a clear indication that it had escaped the heliosphere.
The PLS on Voyager 1 failed in 1980, long before it exited the heliosphere. As a result, the data currently being collected by Voyager 2 will be invaluable for understanding the transition between the heliosphere and interstellar space.
Although both Voyager 1 and 2 have now entered interstellar space, they have not yet left the solar system. Researchers estimate that the boundary of our solar system, known as the Oort Cloud, begins at approximately 1,000 astronomical units (AU) from the Sun and extends an additional 100,000 AU. At their current speed, it will take the two Voyager spacecraft 300 years to enter the Oort Cloud and 30,000 years to travel beyond it.