NASA's Voyager 1 spacecraft is currently riding the wave of an interstellar tsunami, as it continues its historic march out of our solar system. The tsunami emanated from our Sun, and was the third such phenomenon of its type to be detected by the robotic pioneer.
The Voyager program is without doubt one of the most influential and scientifically valuable missions ever undertaken by NASA. The twin spacecraft, launched just 16 days apart, toured many of the largest objects in our solar system, relaying groundbreaking discoveries while capturing the minds and hearts of a generation. The Voyager spacecraft are identical, designed to travel further from our Sun than any mission before it.
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Because of this, the spacecraft could not rely on conventional solar panels to collect the power required to remain functional, instead relying on a power source derived from radioactive decay to keep the twins awake on their long journey. Thanks to the continued presence of Voyager 1 beyond the borders of our solar system, we are learning ever more about the nature of interstellar space.
Contrary to popular belief, the vast expanse between stars is in fact not an empty expanse. Instead, interstellar space is comprised of a sea of charged particles, known as plasma. The so-called interstellar "tsunamis" being detected by the Voyager 1 spacecraft began life as a coronal mass ejection (CME), spewed forth into space by our Sun. A CME throws out enormous clouds of magnetic plasma, and with it, a huge amount of pressure. This wall of pressure eventually strikes the boundaries of our solar system, sending a massive shock wave, or tsunami, through the sea of plasma that makes up interstellar space.
The missions have returned a wealth of imagery, including this 1989 shot of Neptune as taken by the Voyager 2 spacecraft (Image: NASA/JPL-Caltech)
It was by detecting the first of these shock waves that we inferred that Voyager 1 had passed through the heliosphere and entered interstellar space on August 15, 2012. NASA detected plasma rings roughly 40 times more dense than those previously measured, heralding the end of the heliosphere and the frontier of interstellar space. The third and most recent shock wave first detected in February is the largest to date, and according to the most recent reports sent back by Voyager 1, continues to persevere.
Scientists are still unsure as to the speed at which the tsunami is moving, or how wide an area it affects, however it is currently believed that the wave may extend twice as far as the distance between our Sun and the current position of Voyager, which as of September this year was an impressive 125.3 Astronomical Units. Furthermore, data collected by Voyager 1 suggests that as the spacecraft ventures deeper into interstellar space, the denser the surrounding plasma will become. It‘s not yet known whether this is simply a characteristic of interstellar space in general, or one of the distorting effects of the tsunami.
The recording below contains the sound of the ionized matter around the spacecraft "ringing" as the tsunami passes by.