NASA Voyager 2 Nearing Interstellar Space, Measures Increase in Cosmic Rays


NASA’s second probe, the Voyager 2, is making its way outside our solar system. According to the agency’s statement on 5 October, the probe has detected an increase of cosmic rays that come from outside our solar system. This means that the probe might be reaching the outer boundary of the heliosphere.

Voyager 2 is almost 11 billion miles (nearly 17.7 billion kilometers) from our Planet. It was launched in 1977, and scientists have been monitoring it until today. In 2007, they noticed the probe entered the heliosphere – which is the bubble around the solar system formed by solar winds and magnetic fields.

Now, the team is watching for the probe to exit the heliosphere and reaching the heliopause. As soon as it does that, Voyager 2 will join Voyager 1 in being the only two human-made objects that made it to interstellar space.

The Probe’s Instruments Detect More Cosmic Rays

Since the end of August, the Cosmic Ray Subsystem instrument on the probe measured almost 5% increase in cosmic rays hitting the spacecraft compared to the beginning of August. The Low-Energy Charged Particle instrument aboard the probe also detected the increase in high-energy cosmic rays.

Cosmic rays originate outside the solar system. Some of these fast-moving particles are blocked by the heliosphere, so Voyager 2 will soon measure more cosmic rays as it enters the heliopause.

Back in 2012, Voyager 1 went through the same stages that Voyager 2 is detecting these months. Three months before that, Voyager 1 was in the heliosphere. Even though Voyager 2 saw an increase in cosmic rays, the team doesn’t exactly know when the probe crosses the heliopause. Voyager 2 is in a different area in the heliosheath and could make the exit timeline unprobable.

The heliopause contracts and expands during the Sun’s 11-year cycle, so Voyager 2, although launched a few months later than it’s twin, it approaches heliopause six years later than the Voyager 1.

Ed Stone, Voyager Project Scientist at Caltech in Pasadena stated that:

“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.”


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