Voyager 2 is following its twin, the Voyager 1, into interstellar space. NASA revealed that the spacecraft is nearing the edge of the Solar System.
Scientists based the location of the 40-year-old probe on the significant increase of cosmic rays that two of its instruments onboard have detected. The probe is currently almost 11 billion miles away from Earth.
Far From Home
In August, the Cosmic Ray Subsystem, an instrument attached to the Voyager 2 probe, has been measuring a 5 percent increase in the amount of cosmic rays that it has been encountering. The Low-Energy Charged Particle instrument also detected an increase in higher energy cosmic rays.
Cosmic rays are superfast particles believed to be coming from sources outside of the Solar System. In 2012, Voyager 1 also experienced a significant increase of cosmic rays before it became the first ever spacecraft to reach interstellar space.
Approaching The Edge Of The Solar System
Scientists have been observing Voyager 2, which has been traveling in the outermost layer of the heliosphere or the bubble around the solar system formed by solar wind, since 2007. They have been waiting for the spacecraft to reach the heliopause or the boundary between solar wind and interstellar wind.
However, Voyager 2 will not be treading the same path as Voyager 1. The team members behind the project explain that Voyager 2 is currently in a different location in the heliosheath — outer region of heliosphere — which means that the timeline of its exit from the Solar System will be different than Voyager 1.
The Sun's 11-year cycle, which causes the heliopause to move inward or outward, is also changing the journey toward interstellar space of Voyager 2. Unless the spacecraft passes through the heliopause, scientists have no way of telling where exactly in the heliopause it currently is.
"We're seeing a change in the environment around Voyager 2, there's no doubt about that," stated Ed Stone, Voyager project manager, at Caltech. "We're going to learn a lot in the coming months, but we still don't know when we'll reach the heliopause. We're not there yet — that's one thing I can say with confidence."
Voyager 2 as successfully passed by and studied at close range the four gas giants — Jupiter, Saturn, Uranus, Neptune.