Feasibility of characterizing subsurface brines on Ceres by electromagnetic sounding

TL;DR

This paper explores the potential of electromagnetic sounding, using solar wind as a source, to detect and characterize subsurface brines on Ceres, with plans for lunar testing and future Ceres missions.

Contribution

It demonstrates the feasibility of using magnetotelluric methods with solar wind sources to identify subsurface brines on Ceres, avoiding plasma effects encountered in previous lunar studies.

Findings

Electromagnetic sounding can distinguish brine layers from ice and rock.

Method is ready for lunar testing in 2023.

Instrumentation is prepared for a Ceres lander mission.

Abstract

The ice-rich dwarf planet Ceres is the largest object in the main asteroid belt and is thought to have a brine or mud layer at a depth of tens of kilometers. Furthermore, recent surface deposits of brine-sourced material imply shallow feeder structures such as sills or dikes. Inductive sounding of Ceres can be performed using the solar wind as a source, as was done for the Moon during Apollo. However, the magnetotelluric method -- measuring both electric and magnetic fields at the surface -- is not sensitive to plasma effects that were experienced for Apollo, which used an orbit-to-surface magnetic transfer function. The highly conductive brine targets are readily separable from the resistive ice and rock interior, such that the depth to deep and shallow brines can be assessed simultaneously. The instrumentation will be tested on the Moon in 2023 and is ready for implementation on a Ceres landed mission.