Detection of Subsurface Liquid Water Using Magnetotellurics on Mars

The characterization of past or present water on Mars remains a core goal of the Mars exploration program, representing a cross-cutting theme that ties together investigations relevant to life, climate, geology, and the identification of sites for future exploratory landed missions. Passive, low frequency electromagnetic (EM) soundings of the subsurface can identify salinated liquid water at depths ranging from hundreds of meters to ~10 km in an environment such as Mars. Among the tools necessary to perform these soundings are low frequency electric and magnetic field sensors capable of being deployed from a lander or rover. With support from both the NASA Planetary Instrument Definition and Development Program (PIDDP) and Mars Instrument Development Program (MIDP), we are currently developing an autonomous sensor platform that can perform magnetotelluric soundings in environments such as Mars within the constraints of current lander or rover architectures. Once fully developed, this technique will represent both a complementary and alternative method to orbital radar sounding investigations, performing deep soundings at sites identified as high priority areas by orbital radars or detecting subsurface water in environments that render radar methods ineffective. In either case, the sensitivity and depth of penetration inherent in low-frequency EM exploration makes this tool a compelling candidate method to identify subsurface liquid water from a landed platform on Mars or other targets of interest. We will describe current results obtained with our prototype systems from various terrestrial field sites, discuss sources of passive EM energy on Mars, and how these measurements might be conducted on future missions.