Space by Elizabeth Howell 10/30/2019
Goodbye, heliosphere! Hello, interstellar space!Humanity should consider building an interstellar probe to see our neighborhood from an outside point of view, argued several scientists at a recent conference.
NASA's Voyager 1 and 2 spacecraft are the only machines that people have sent beyond our solar system. These 42-year-old spacecraft are still functioning well enough to send us information from interstellar space, and many of their insights have been surprising, according to Stamatios (Tom) Krimigis, the principal investigator of the low-energy charged particle experiment that is still working on both spacecraft.
"The models have been wrong," Krimigis told delegates on Oct. 25 at the International Astronautical Congress held here. One prominent example was the shape of the heliosphere, or the region of space in which the stream of charged particles emanates from our sun and wraps around the solar system. Until the 2010s, scientists thought it had a fan shape; the Voyagers, upon crossing the heliosphere in 2012 and 2018, revealed it is more like a bubble.
Another surprise was finding out where cosmic rays (radiation from outside the solar system) are accelerated, he said. Before the Voyagers went into interstellar space, scientists thought these particles accelerate at the termination shock area, which is where the particles from the sun slow down to below the speed of sound. The Voyagers revealed the acceleration actually takes place in the heliosheath, the region of space just beyond the termination shock zone.
More:
https://www.space.com/interstellar-probe-science-of-solar-system.html
