Voyager probes, launched into space in 1977, are still contributing to science 43 years later, billions of kilometers from their home planet in interstellar space. Using instruments on board Voyager 1 and Voyager 2, American researchers have discovered a new type of bursts of electron cosmic rays from the Sun, accelerated by shock waves resulting from large eruptions on the star.
A few days after the burst of accelerated electrons, the oscillations of the plasma wave, caused by electrons with lower energy, reached the instruments of the spacecraft, and a month later – the shock wave itself. According to physicists, these electrons move in the interstellar medium at a speed close to the speed of light – about 670 times faster than the shock waves that gave them momentum. Reflecting from the enhanced magnetic field at the edge of the shock wave, electrons spiral along the lines of force of the interstellar magnetic field, gaining speed as the distance between them and the shock wave increases. Interestingly, the shock waves took more than a year to reach the Voyager probe, which is more than 22 billion kilometers from the Sun.
In a press release from the University of Iowa, research leader Distinguished Professor of Physics and Astronomy Don Gurnett explained: “When the shock wave first touches the interstellar magnetic field lines passing through the spacecraft, it reflects and accelerates some of the electrons from the cosmic rays. We have determined with our instruments that these are electrons that have been reflected and accelerated by interstellar jolts propagating outward from energetic solar events on the Sun. This is a previously unknown mechanism. “
The mechanism of particle acceleration by shock waves itself is not new, but scientists have not previously recorded it in the interstellar medium, which is very different from the solar wind, where similar processes were previously observed. The researchers believe the results could improve understanding of cosmic radiation and shock waves. Ultimately, they can help protect astronauts from radiation exposure when flying into deep space.
But the very possibility of new discoveries with the help of equipment that is ancient by modern standards is remarkable. Both Voyager probes use very old electronics: the frequency of their processors is only 250 kHz versus gigahertz for modern (even consumer) chips, and it takes about a day and a half to communicate with the devices. This is another proof of the technology’s reliability. But there is less and less hope for new discoveries, with the latest scientific instruments on every spacecraft expected to fail around 2025.
Interestingly, in November, scientists reported that they were able to restore two-way communication with the Voyager 2 probe: due to the repair and renovation of the DSS43 (Deep Space Station 43) antenna located in Canberra (capital of Australia), the device was independent flight. The specialists could only receive certain information from the space station, but not send control commands.
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