Radioisotope power system-based enceladus smallsat mission concept: Enceladus express

The coming decades of planetary science and deep space exploration will likely have a combination of more ambitious missions and ever more constrained budgets. The outer solar system, in particular, poses a challenge for lower mission cost as the principal need for a robotic craft — a source of energy — is difficult to supply through conventional means (solar energy). Even as far from the Sun as Saturn, the solar energy density is only 1% of that at Earth. Not viewed typically as a power source for low-cost missions, radioisotope power systems (RPS) may well fill that role by providing power to small spacecraft in the outer solar system. And the outer solar system beckons with extremely compelling science. The rich dynamics of the atmospheres of the gas giants are continuously operating laboratories of extreme weather processes, examples of which in miniaturized scale may become more familiar here on Earth. Enceladus, a small moon of Saturn, has been seen by the Cassini mission to be a site of continuous high geologic activity, with plumes of water vapor and particles pumped hundreds of kilometers above the surface, indeed into Saturn orbit. The internal heating mechanisms of this activity beg for explanation, and more importantly, initial measurements by the Cassini spacecraft give tantalizing clues that the geo-thermal source of the heating is, in fact, maintaining a global sub-surface ocean, which in combination could provide a habitat for life. This paper will explore how existing and currently available RPS elements may make mission concepts to explore the intriguing science of Enceladus economically tractable, and at the same time provide a generic platform for other small but highly capable spacecraft to explore the outer solar system.