Accessing Icy World Oceans using Lattice Confinement Fusion Fast Fission

NASA’s Ocean Worlds Exploration Program [1,2] has the challenge of penetrating the many kilometer-thick ice caps in its search for extraterrestrial life on icy worlds. These icy ocean worlds include Ceres, Europa, Enceladus, and Pluto. Each world may have a liquid water ocean beneath their ice crust. These oceans are likely heated by the parent planet’s tidal forces, or in the case of Pluto or Ceres, by residual radioactive decay. A robotic probe exploring the oceans beneath must either melt or bore through the ice crust first. Consequently, the proposed probe needs to contend with hydrostatic ice pressure, ice phase and density changes, then water pressure. Such a mission requires a small, but robust and long lived, electrical energy and heat source.

The proposed innovation is a compact, scalable nuclear energy source that does not use highly enriched uranium (HEU), high-assay enriched uranium (HALEU), low enriched uranium (LEU) nor plutonium-238 (238Pu). The nuclear energy source consists of a hybrid fusion-fast-fission method whereby neutrons generated from Lattice Confinement Fusion (LCF) are used to fission materials such as depleted uranium or thorium. LCF has been demonstrated by both NASA (published in Physical Review C [3]) and by Lawrence Berkeley National Laboratory (published in the Journal of Applied Physics [4]), and commercialized by Astral System, Ltd. [5] Although these methods are reminiscent of Low Energy Nuclear Reactions (LENR), both methods operate at much higher energies than any attempt at cold fusion. This new hybrid energy
source is sufficient to provide power and heat for melting or boring through icy caps with untethered, autonomous probes. These probes can be used for planetary (i.e., Pluto), lunar (i.e., Enceladus), or asteroid (i.e., Ceres) exploration where icy caps are encountered.

As an alternative to only melting, we propose (ultra) sonically assisted ice fracturing, borrowing from Navy research on super-cavitating torpedoes while noting the Europa Tunnelbot [6] (as shown in Fig 2) proposed a sonar transceiver for navigation. Although high speed transit isn’t expected (mission
specifications expect 3 years to transit the ice [6]), super-cavitation involves a sheath of bubbles along a torpedo [7] thereby reducing friction with water. We recognize that the extreme pressures preclude bubble formation, but a thin skin of liquid water would be expected to form along the probe surface. This method is analogous to a possible means of penetrating ice via a melted ice sheath vibrating against and fracturing local ice. In addition, like sonar, a sonic transducer can operate in a pump-probe manner, listening to return echoes to measure ice density directly and possibly communicate to the surface from some depth within the ice.