Voyager spacecraft finds entirely new ‘unique physics’ outside the solar system

Voyager probes have detected a whole new type of electron burst outside the solar system.

This is the first time that this “unique physics” has been detected by a spacecraft, and could allow new breakthroughs in our understanding of the “interstellar medium”, or the space between stars.

The two Voyager spacecraft were launched by NASA over 40 years ago with the aim of flying to the far reaches of our solar system. They have now gone even further, reaching interstellar space and exploring the spaces between the stars, giving us the first glimpses of what it could be like in this mysterious area.

The spacecraft’s latest discovery – using data from Voyager 1 and 2 – saw them pick up bursts of electrons like never before. They discovered that cosmic ray electrons are accelerated by shock waves that originate in major flares on the sun, and then are sent into space.

The electron shards travel ahead of the shock waves that project them into space. Electrons move almost at the speed of light, accelerating along magnetic field lines.

Soon after, the lower energy electrons arrive, sometimes taking days to do so. Then the shock waves themselves are detected by the spacecraft, sometimes up to a month later.

The shock waves themselves come from coronal mass ejections, which are clusters of hot gas and energy that are projected out of the Sun at about a million kilometers per hour. The Voyager spacecraft is now so far away that even at this speed it takes them a year to be detected.

“What we are seeing here specifically is a certain mechanism by which, when the shock wave first makes contact with the interstellar magnetic field lines passing through the spacecraft, it reflects and accelerates some of the electrons from 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 propagating outward from solar energy events in the sun. It is a new mechanism.

Scientists now hope they can use this discovery to better understand both shock waves and the radiation itself.

This in turn could help inform considerations when sending astronauts on long missions to the Moon or Mars, as they will be exposed to many more cosmic rays than we would on Earth.