A magnetotelluric instrument for probing the interiors of Europa and other worlds

One objective of a lander mission to Jupiter's icy moon Europa is detect liquid water within 30 km as well characterizing the subsurface ocean. In order satisfy this objective, ice shell must also be identified. Inductive electromagnetic (EM) methods are optimal for detection on because even small fraction dissolved salts will make orders magnitude more electrically conductive than shell. Compared induction studies by Galileo spacecraft, measurements higher-frequency ambient EM fields necessary resolve shallower depths intrashell water. Although these have been mostly characterized prior missions, their unknown source structures and plasma properties do not allow sounding using single surface magnetometer or orbit-to-surface magnetic transfer function, respectively. Instead, broadband can accomplished from station magnetotelluric (MT) method, which measures horizontal electric three-component field. We developed prototype Magnetotelluric Sounder (EMS) meet measurement requirements in relevant thermal, vacuum, radiation environment. EMS comprises central electronics, fluxgate mast, three ballistically deployed electrodes measure differences potential. paper, we describe development testing providing supporting information concept operations calculations detectability. uniquely determine occurrence Europa, important constraints habitability.