Voyager spacecrafts have detected bursts of cosmic rays

NASA launched Voyager 1 and Voyager 2 more than 40 years ago, and despite their age, both spacecraft are still making discoveries. A new study led by physicists from the University of Iowa has reported the first detection of cosmic ray electrons accelerated by shock waves that originate from major sun eruptions. The researchers say the detection was made by instruments aboard both Voyager 1 and Voyager 2.

Both the Voyager spacecraft are currently journeying through interstellar space and are the first spacecraft to record this phenomenon in the space between stars. Researchers note the electron bursts are traveling at nearly the speed of light, about 670 times faster than the shockwaves that pushed them initially. The bursts were followed by plasma wave oscillations, which researchers say are caused by lower-energy electrons arriving at the instruments aboard the Voyager spacecraft days later.

In some cases, the shockwave itself arrived as long as a month after the bursts. Shock waves recorded by the spacecraft originated from coronal mass ejections, large expulsions of hot gas, and energy that come from the sun. Those expulsions move outward from the sun at a speed of about 1 million mph. Despite the incredible speed, it still takes over a year for the shock waves to reach the Voyager spacecraft.

The Voyager spacecraft are currently more than 14 billion miles from the sun, further than any human-made object. Physicists say the discovery could help improve our understanding of the dynamics of shock waves and cosmic radiation originating from flare stars and exploding stars. A better understanding of these phenomena is crucial because they must be considered when sending astronauts on extended lunar or Martian missions.

Astronauts in space are exposed to significantly more radiation than we are on Earth. Physicists think that the electrons in the interstellar medium are reflected off a strengthened magnetic field at the edge of the shock wave resulting in acceleration by the shock wave's motion. Reflected electrons spiral along interstellar magnetic field lines and gain speed the further they get from the shock.