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Voyager probes have detected an entirely new type of electron blast outside the solar system.
It is the first time that this “unique physics” has been detected by a spacecraft and it could allow new breakthroughs in our understanding of the “interstellar medium”, or the space between stars.
The two Voyager spacecraft were launched by NASA more than 40 years ago, with the aim of flying to the edge of our solar system. Now they have gone even further, reaching interstellar space and exploring the spaces between the stars, giving us the first glimpses of what that mysterious area might look like.
The spacecraft’s latest discovery, using data taken from both Voyager 1 and 2, saw them collect electron bursts like never before. They found that electrons in cosmic rays are accelerated by shock waves that originate in the sun’s major eruptions and are then launched into space.
The electron bursts travel in front of the shock waves that launch them into space. Electrons travel at nearly the speed of light, accelerating along the magnetic field lines.
Soon after, low-energy electrons arrive, sometimes taking days to do so. Then the shock waves themselves are detected by the spacecraft, sometimes even a month later.
Shockwaves come from coronal mass ejections, which are clusters of hot gas and energy that are projected from the Sun at about one million miles per hour. Voyager spacecraft are now so far away that even at that speed they take a year to detect.
“What we’re seeing specifically here is a certain mechanism whereby when the shock wave first comes into contact with the lines of the interstellar magnetic field passing through the spacecraft, it reflects and accelerates some of the electrons of the cosmic rays, ”says Don Gurnett, professor emeritus of physics and astronomy in Iowa and the corresponding author of the study.
“We have identified through cosmic ray instruments these are electrons that have been reflected and accelerated by interstellar shocks that propagate outward from energetic solar events to the sun. This is a new mechanism.”
Scientists now hope they can use this discovery to better understand both the shock waves and the radiation themselves.
This in turn could help take into consideration when sending astronauts on long missions to the Moon or Mars, as they will be exposed to far more cosmic rays than we would on Earth.
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