The icy moons of the solar system represent the most promising targets for astrobiological exploration. Direct access to the geyser vents of Enceladus would be highly desirable to acquire pristine biological samples but considered very challenging. The location of the landing target, one of the plume sources, is unknown a priori that must be inferred by the landing vehicle itself during the descent. We present an approach that offers the prospect of targeting the source of the Enceladian icy plumes using one or more penetrators. Penetrators are small missile-type entry descent and landing vehicles that can carry modest scientific instruments capable of withstanding impact into the subsurface. By continuously measuring the concentration of the icy plume, the penetrator can locate the plume source and target it for impact. The penetrators' trajectory and plume source localization are addressed. Calculations of the sphere of influence, the free fall time and the penetrator impact velocity are input parameters from which we design three types of descent profiles. The descent profile involves vectoring-in-forward-flight (viffing) - it may be ballistic (with minimal ?V cost), planar viffing (with modest ?V costs), a hybrid approach of nested boxes (with intermediate ?V cost) or quasi-spiral (with highest ?V cost) for which we present trajectory maneuver simulations. The simulations illustrate that the quasi-spiral profile is favored and is tolerable with modest ?V costs traded with targeting accuracy. We determine that the proposed vectoring-in-forward flight (viffing) maneuvers is feasible and permits accurate targeting of Enceladus' subsurface vents.

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Keywords Enceladian plume, Planetary penetrator, Spiral descent, Vector-in-forward-flight
Conference 70th International Astronautical Congress, IAC 2019
Sun, Y. (Yue), Ellery, A, & Huang, X. (Xianlin). (2019). Targeting Enceladus' Geyser vents using penetrators employing biomimetic plume sniffing. In Proceedings of the International Astronautical Congress, IAC.