NASA Voyager 2, released for exploration of the outer planets of the solar system, made its first testimony from interstellar space, collected more than 11 billion miles in forty years, analyzed by scientists.
This is only the second probe to sail out of the heliosphere – the expansive region made of plasma and magnetic fields generated by the sun. He finally freed himself from the solar system to enter the interstellar space last year, joining his twin satellite Voyager 1, which came out in 2012.
The data transmitted was analyzed by a large team of physicists and their findings were published in five papers on Nature Astronomy on Monday this week. In particular, studies evaluate Voyager 2 measurements of cosmic rays, magnetic fields, plasma and particle densities in and out of the heliosphere.
Many of the findings confirm what was discovered when Voyager 1
The heliosphere is a giant protective balloon, that protects the solar system from galactic cosmic rays. Made of plasma, it is often described as the solar wind that flows throughout the system and blocks it from continuing further through pressure in the interstellar environment. The small region between the two regions is known as heliosheath, and the bubble edge is known as heliopause.
A diagram describing the different parts of the heliosphere, the interstellar environment and where Voyager spacecraft have traveled. Image Credit: NASA / JPL-Caltech
Voyager 2 found that plasma temperatures in the surrounding interstellar environment were lower than those in the heliosphere. The measurements also confirm that the plasma density is higher on the outside compared to the inner, heliosphere.
As the cheekbone probe passed through the inner edge of the heliopause, the plasma density suddenly exploded for some unknown reason. Researchers believe the plasma is compressed and not quite sure what drives the particles.
Interestingly enough, Voyager 2 detects a stream of particles in the heliosphere to leak into the interstellar space – and the leakage is greater than previously observed with Voyager 1.
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One remaining mystery is the direction of the magnetic field on either side of the heliopause. They appear to be parallel or aligned with other words, but no one knows why. This alignment was discovered by Voyager 1 and is now confirmed by Voyager 2 data.
"In the historical sense, the old idea that the solar wind would simply gradually be extinguished as you go further into interstellar space is simply not true "said Don Garnett, co-author of a second paper on plasma density and a physics and astronomy professor at the University of Iowa in the US." We show with Voyager 2 – and before that with Voyager 1 – that there is a clear boundary there. It's just amazing how fluids, including plasma, form boundaries. "
Voyager 1 has traveled more than 13.6 billion miles (22 billion kilometers) from the Sun, while Voyager 2 is 11.3 billion miles (18.2 billion kilometers). Both probes will continue to accelerate in depth.
"The two Voyagers will outlive the Earth," says Bill Kurt, co-author of one of the papers and a researcher at the University of Iowa. "They are in their own orbits around the galaxy for five billion years or more. And the likelihood of them encountering something is almost zero. "®
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