Testing of SLUSH ice penetrating probe in Europa, Enceladus, and Mars environments

Europa and Enceladus conceal global liquid-water oceans beneath ice shells several kilometers thick, and Mars holds thick polar ice deposits that may cover localized layers of liquid water or brine. These subsurface environments are primary targets in the search for past or present life in the solar system. The Search for Life Using Submersible Heated drill (SLUSH) probe is a hybrid, thermo-mechanical probe capable of penetrating through the ice to reach the subsurface liquid water. To improve efficiency and drilling speed, SLUSH combines the two existing methods for traveling through ice: thermal (melting) and mechanical (cutting). “Slushing” uses rotary-percussive drilling to break the ice into chips (the fragmented ice cuttings produced by the drill) and heat to partially melt these chips into a slush, enabling efficient transport behind the probe. A scaled prototype of the SLUSH probe has been developed to compare the three drilling methods (thermal, mechanical, and thermo-mechanical or slushing). Testing was conducted in relevant ambient pressure and vacuum environments using “warm” (260 K) and “cryogenic” (130 K) ice. An analytical thermal model is applied to estimate the idealized performance of a conventional melt probe as an upper-bound baseline, and a conceptual power-balance framework is introduced that decomposes the slushing power requirement into mechanical and thermal contributions relative to this baseline. Initial testing demonstrated the feasibility of the slushing approach across all three environments and identifies key design drivers for future optimization.