Such signals are known for a long time: they are called decametric radio emission (Decametric Radio Emission). However, for the first time, the spacecraft recorded them in close proximity to the place of origin. In fact, the probe flew through the source of the radio spelling, not far from the Ganyed, the largest satellite of Jupiter.
Juno sensors observed a phenomenon of about five seconds, and then it merged with background radiation. Considering the speed of the probe - about 50 kilometers per second, it can be concluded that the space where the signal is generated is generated, has about 250 kilometers in the diameter.
On noteworthy observation, the international team of researchers reported some time ago. The original publication was posted in a reviewed magazine Geophysical Research Letters. Public attention she attracted after the transfer on the KTVX channel, where the NASA representative was performed in Utah Patrick Wiggins (Patrick Wiggins).
True, journalists for some reason ranked a signal in the orbit of Jupiter (6.5-6.6 megahertz) to the FM ranges (65-108 megahertz) and Wi-Fi (2.4 gigahertz or 5.1-5.8 gigahertz). Perhaps the comparison was made to show that radio waves belong to the range used in the earth's connection, and the decamer transceivers are not familiar with most.
Telling the audience about the recorded Juno radio signal, Patrick noted that its origin is natural. Such radio spells arise as a result of cyclotron maser instability (CMI, Cyclotron Maser Instability). The essence of this effect is to enhance with free radio wave electrons. It happens if the frequency of electron oscillations in a plasma is significantly lower than their cyclotron frequency. Then it can become noticeable even well-sensitive random signal in the cloud of charged particles.
Radio sponsors are formed in those areas of the magnetosphere of Jupiter, where it interacts closely with the magnetic field of the Ganamed. Electrons captured by magnetic lines can not only generate radio waves. Another effect that Juno managed to watch, "X-ray polar radiance in the atmosphere of the Jupteean Moon.
In 2011, the JUNO apparatus studies gravity and magnetic field of Jupiter, its atmosphere and internal structure. He went to the orbit of the Gaza Giant in 2016 and already at least forced scientists to seriously revise the theory of the emergence of polar radiances on this planet. The main tasks of the mission were successfully implemented, and in 2021 the probe will study the Galilean satellites.
Source: Naked Science