Exoplanet Science Strategy White Paper
Submitted to the National Academies of Sciences, Engineering and Medicine, Space Studies Board
Future remote sensing of exoplanets will be enhanced by a thorough investigation of our solar system Ice Giants (Neptune-size planets). What can the configuration of the magnetic field tell us (remotely) about the interior, and what implications does that field have for the structure of the magnetosphere; energy input into the atmosphere, and surface geophysics (for example surface weathering of satellites that might harbour sub-surface oceans). How can monitoring of auroral emission help inform future remote observations of emission from exoplanets? Our Solar System provides the only laboratory in which we can perform in-situ experiments to understand exoplanet formation, dynamos, systems and magnetospheres.
Within the past decade it has been realized that Neptune-size planets are among the most common class of exoplanet in our galaxy, [Fulton et al., 2017]. In situ study of an Ice Giant will enable numerous investigations that, despite several decades of study, are still not fully understood. These include the following top-level questions that have direct relevance to exoplanets:
Auroral configuration and emission - unlike our Solar System, eccentric and complex orbital characteristics appear to be common in other planetary systems, so that the understanding of radio emission produced by Uranus could have profound importance for interpreting future radio detections of exoplanets.
Magnetospheric Transport/Atmospheric Energy Deposition - mechanisms for plasma transport and diffusion, that are well understood at other planets, have never been studied in this type of geometry.
Radiation Belts (Energetic Particle Trapping) - how stable are the Uranian radiation belts? Are they always present? Can we guide the search for exoplanets with magnetic fields by identifying which of them have radiation belts?
Bulk Composition and Internal Structure - understanding the composition and structure of our Solar System’s ice giants is a necessary prerequisite to identifying them around other stars from the minimal information available (such as mass and radius), and recognizing if those exoplanetary systems contain a type of planet not seen in our Solar System.
Intrinsic magnetic field - understanding the dynamos of our solar system, we would be able to predict the magnetic field strengths and morphologies of exoplanetary dynamos with more confidence.
