UMaMI: A New Frontiers-style Mission Concept to Explore the Uranian System

Abstract

With the public and scientific community’s growing interest in ocean worlds, the icy moons of Uranus offer an ideal opportunity to explore a native ice giant satellite system. Although it is uncertain whether any of the Uranian moons currently host subsurface oceans, there is tantalizing evidence—including geologically young surface features and volatiles that are not stable—that this could be the case, making these objects possible ocean worlds in their own right. Determining whether subsurface oceans are present in the interiors of these moons would increase our understanding of the conditions under which subsurface oceans are formed and maintained over the history of the solar system. The presence and stability of a subsurface ocean in the interiors of any icy body is key to identifying its potential as a habitable environment. In this work, we describe a midsize (New Frontiers class) mission concept: the Uranian Magnetosphere and Moons Investigator. The magnetosphere and moons are tightly coupled parts of the Uranian system, complementary to study, and best analyzed together in order to investigate the Uranian moons as potential ocean worlds. Additionally, this mission concept includes study of Uranus’s unique rings and magnetosphere–solar wind interaction. With a future, more detailed trade study, there also could be opportunities for studies of Uranus itself.

A CO2 Cycle on Ariel? Radiolytic Production and Migration to Low-latitude Cold Traps

“…To fully characterize the life cycle of CO 2 ice on the classical Uranian satellites, a spacecraft equipped with a visible wavelength camera and NIR mapping spectrometer, making multiple close flybys of these moons, is needed to reveal their previously unimaged northern hemispheres, measure the localized distribution and spectral signature of CO 2 ice, and characterize any possible associations between CO 2 ice and geologic landforms like craters and chasmata that might serve as cold traps (e.g., Cartwright et al 2021;Leonard et al 2021). Similarly, a Uranus orbiter equipped with a plasma spectrometer and an energetic particle detector could measure Uranus's magnetosphere proximal to Ariel and the other moons, thereby providing critical context on moon-magnetosphere interactions that could be driving CO 2 production and volatile cycling on these moons (e.g., Kollmann et al 2020).…”

Crater Distributions of Uranus's Mid-sized Satellites and Implications for Outer Solar System Bombardment

“…This work represents just the beginning of interpreting these data and understanding the bombardment of the outer solar system. One of the best next steps is to send orbiters to the Uranus (Cartwright et al 2021;Leonard et al 2021) and Neptune systems 6 to complete crater measurements to much smaller diameters and deepen understanding of the satellites' geologies. It is also important to perform occultation surveys of KBOs, including bodies with diameters <1 km (Huang et al 2021), as escaped KBOs are the expected main source of the heliocentric population of satellite impactors.…”

Ariel's Elastic Thicknesses and Heat Fluxes

“…Furthermore, a magnetometer on an orbiter could search for induced magnetic fields in Ariel, a key diagnostic trait of internal salty oceans (Cochrane et al 2021;Weiss et al 2021). Thus, a Uranus orbiter would dramatically improve our understanding of the surface and interior of Ariel, as well as the other Uranian moons, thereby helping us determine whether these moons are, or were, ocean worlds Cartwright et al 2021;Leonard et al 2021;Bierson & Nimmo 2022;Cohen et al 2022).…”