A light sail astrobiology precursor mission to Enceladus and Europa

Abstract

Icy moons with subsurface oceans of liquid water rank among the most promising astrobiological targets in our Solar System. In this work, we assess the feasibility of deploying laser sail technology in precursor life-detection missions. We investigate such laser sail missions to Enceladus and Europa, as these two moons emit plumes that seem accessible to in situ sampling. Our study suggests that GigaWatt laser technology could accelerate a $100$ kg probe to a speed of $\sim{30}\, \mathrm{km\, s^{-1}}$, thereupon reaching Europa on timescales of $1$-$4$ years and Enceladus with flight times of $3$-$6$ years. Although the ideal latitudes for the laser array vary, placing the requisite infrastructure close to either the Antarctic or Arctic Circles might represent technically viable options for an Enceladus mission. Crucially, we determine that the minimum encounter velocities with these moons (about ${6}\,\mathrm{km\,s^{-1}}$) may be near-optimal for detecting biomolecular building blocks (e.g., amino acids) in the plumes by means of a mass spectrometer akin to the Surface Dust Analyzer onboard the \emph{Europa Clipper} mission. In summary, icy moons in the Solar System are potentially well-suited for exploration via the laser sail architecture approach, especially where low encounter speeds and/or multiple missions are desirable.