Deep subsurface exploration of planetary ice enabled by nuclear power

The exploration of subsurface ice environments on the Mars polar caps, as well as the icy moons of the outer solar system, has gained increasing attention in recent years. A number of mission concepts have been developed to varying degrees to explore these subsurface regions. In prior studies the ability to access these environments to significant depths has been limited primarily by the power systems available for application to such missions. The current state of development of compact nuclear fission power sources, however, brings new conceptual opportunities for deep, long-term exploration in planetary ice, enabling missions to explore the full depth of the Martian ice caps and potentially to explore the icy shells of the Jovian moons. In this paper a complete mission design is presented for one such mission to the north pole of Mars. The mission concept includes a design for a potential lander configuration based on adaptation of current technology as developed in early studies for the Mars Science Laboratory (MSL) project. The mission design also makes use of the basic entry, descent, and landing (EDL) proposed for MSL, with modifications to accommodate the configuration and mass of the ice probe and other landed elements. Two alternative methods of ice exploration are discussed, both enabled by a small 15 kW (thermal) surface fission power system. The first of these designs considers a lander-mounted reactor configuration with the reactor supplying 3 kW of electrical power to an electrically heated ice probe, based on designs currently in development and tested in terrestrial applications. The second concept considers a design in which the nuclear reactor is incorporated directly into the body of the ice probe, allowing the full thermal output of the reactor to be used in melting the ice. Each of these concepts brings distinct system design advantages, which are discussed in the paper, as well as the potential application of these concepts to the exploration of other solar system bodies.