ER Fellowship - Mass Transport and Loss in Planetary and Astrophysical Magnetospheres

I want to understand how charged material (plasma) is transported in the space around the planets Mercury, Jupiter and Saturn, and around stars in our galaxy and beyond. The solar wind is a stream of plasma that comes off the Sun and blows out into interplanetary space. Some planets have their own invisible magnetic field which stretches huge distances out into space and acts like a shield, holding off this solar wind flow so that much of it is deflected around the planet. Behind this shield lies the planet's magnetosphere, like a giant magnetic bubble. Outside of our solar system, there are similar winds, blowing near stars and creating stellar magnetospheres. Both planetary and stellar magnetospheres are full of plasma. Plasma parcels are tied to magnetic field lines, like beads on a string. There are several ways for this plasma to get into the magnetosphere. It can erupt from volcanic moons or spew out of the rings. It can also enter from the outside, when plasma from the solar wind or stellar winds can penetrate the magnetospheric boundary (the edge of the bubble). As with any system, what goes in must come out. The magnetospheric bubble cannot inflate forever. Orbiting spacecraft have seen material moving around inside magnetospheres and escaping out the sides. There are several sophisticated theories about how charged material can move around under the influence of a magnetic field, but there is a problem: The current theories cannot explain the observations. There is a significant imbalance in the mass budget of magnetospheres. We know roughly how much material goes in, but we don't see it all leave. This work will find out where this missing material goes. It will involve searching for close-up evidence of several fascinating plasma processes, including plasma interchange and magnetic reconnection. Plasma interchange is a slippy, slinky process in which regions of hot, thin plasma silently swap places with regions of cold, thick plasma. In this way, the thick plasma can move away from the centre of the magnetosphere, stretch out on its accompanying field lines, and form a thin disk around the equatorial plane. Reconnection is a noisy and explosive process where these stretched field lines can dramatically break, releasing huge amounts of stored up energy. We know a lot about these processes in Earth's magnetosphere because there are many satellites flying around in space near Earth measuring these plasma motions. However, we can learn much more by applying this knowledge further afield and exploring how the situation may be different in other environments. Saturn and Jupiter are huge planets which rotate very rapidly and have a lot of plasma inside their magnetospheres due to exotic volcanic moons and rings. Mercury on the other hand is a much smaller planet and is much more vulnerable to the effects of the solar wind blowing at it as it is so close to the Sun. Stellar magnetospheres are the most dramatic of all due to their enormous size. It is fascinating to think that energy release processes at stars many millions of kilometres away can be so dramatic that we can observe them with telescopes here on Earth! Every planet and every star has a unique character, which is why I find studying similar physics in these exotic and diverse environments so challenging. The rewards for studying a range of environments for me are much greater than studying one place only.