Venture Deep, the Path of Least Resistance: Crevasse-Based Ocean Access Without the Need to Dig or Drill

Abstract

The Cassini Mission unveiled Enceladus as a key target for astrobiology exploration in the coming decade (Schenk et al., 2018, and references therein). The Enceladus plume provides a unique pathway to sample from, and potentially travel to, an alien ocean. This ocean is global and habitable, containing all ingredients for life as we know it - “extended regions of liquid water, conditions favorable for the assembly of complex organic molecules, and energy source(s) to sustain metabolism” (Des Marais et al., 2008). A future mission to Enceladus, built with today’s technology, could address a pivotal question that reaches civilization-level science: Are we alone? However, Enceladus presents many mobility challenges. The majority of grains emitted from the plume fall back onto the surface of this moon (Porco et al., 2017). At 1% Earth’s gravity, this unconsolidated plume ejecta likely fluidizes when disturbed, making traditional wheeled mobility untenable. Sintering of the ice grains might also need to be accounted for. Various models of how the plume is driven provide a wide range of environments to be traversed, not only on the surface but within the vent itself, which may be circuitous or constricted. The vent interior dimensions could also vary over the orbital period of Enceladus. With a ~2.5 hour round trip communications time and the dynamic environment of the plume and ocean, any mission looking to access the ocean through the vent system must be fully autonomous. An adaptable, autonomous robotic architecture is capable of navigating Enceladus’ surface and reaching the subsurface ocean in the coming decade.