Uranus: Why the radiation belt of the ice giant is so unusual
Uranus is different from the other planets in the solar system in many respects. So far, it has only been visited once by a probe.
According to new findings, the unusual magnetic field of Uranus may have an effect on the planet's radiation ring.
(Image: NASA)
Compared to other planets in the solar system, Uranus is still little explored and poses many puzzles for researchers. They may now have solved one of them: An international team may have found an explanation as to why the ice giant has a surprisingly weak radiation belt. As the scientists report in the journal "Geophysical Research Letters", the planet's unusually tilted and asymmetrical magnetic field could be responsible for this phenomenon.
The discovery is based on data from the Voyager 2 space probe, which was the only spacecraft to visit Uranus in 1986. At that time, the researchers found that the planet's radiation belts were around 100 times weaker than expected. At the same time, the magnetic field of Uranus was found to be inclined by around 60 degrees to the axis of rotation and strongly asymmetrical. This is unique in the solar system.
Voyager 2 provided the necessary data
New simulations based on the Voyager 2 data now suggest that these two peculiarities could be connected. "Our hypothesis was that the magnetic asymmetry deforms the proton radiation belts and forms regions around the planet where the radiation belts are more compressed and others where they are more spread out," explains study leader Matthew Acevski.
The calculations show that charged particles in the radiation belts are accelerated and decelerated by the uneven magnetic field strength. This leads to "traffic jams" in some areas and a spread in others - similar to traffic jams on a ring road. The researchers suspect that Voyager 2 happened to fly through a region with a lower particle density, which could explain the unexpectedly low readings.
New Uranus mission planned
Although the model does not fully explain the observed 100-fold lower intensity, it could make an important contribution to understanding the Uranus magnetosphere. The results are also likely to be relevant for the planned NASA mission to Uranus, which could be launched in 2030 according to current plans. "A new mission could allow us to discover completely new physical phenomena that we cannot even predict with simulations," says Acevski.
The "Uranus Orbiter and Probe (UOP)" mission would take around 13 years to reach its destination. A four-and-a-half-year mission is planned on site, during which several of the planet's moons will be studied in addition to Uranus and its rings.
(mki)
