The plumes discovered by the Cassini mission emanating from the south pole of Saturn's\r\nmoon Enceladus and the unique chemistry found in them have fueled speculations that\r\nEnceladus may harbor life. The presumed aquiferous fractures from which the plumes\r\nemanate would make a prime target in the search for extraterrestrial life and would be\r\nmore easily accessible than the moon's subglacial ocean.\r\nA lander mission that is equipped with a subsurface maneuverable ice melting probe\r\nwill be most suitable to assess the existence of life on Enceladus. A lander would have to\r\nland at a safe distance away from a plume source and melt its way to the inner wall of the\r\nfracture to analyze the plume subsurface liquids before potential biosignatures are\r\ndegraded or destroyed by exposure to the vacuum of space. A possible approach for the\r\nin situ detection of biosignatures in such samples can be based on the hypothesis of\r\nuniversal evolutionary convergence, meaning that the independent and repeated emer-\r\ngence of life and certain adaptive traits is wide-spread throughout the cosmos. We thus\r\npresent a hypothetical evolutionary trajectory leading towards the emergence of metha-\r\nnogenic chemoautotrophic microorganisms as the baseline for putative biological com-\r\nplexity on Enceladus. To detect their presence, several instruments are proposed that may\r\nbe taken aboard a future subglacial melting probe.\r\nThe “Enceladus Explorer” (EnEx) project funded by the German Space Administration\r\n(DLR), aims to develop a terrestrial navigation system for a subglacial research probe and\r\neventually test it under realistic conditions in Antarctica using the EnEx-IceMole, a novel maneuverable subsurface ice melting probe for clean sampling and in situ analysis of ice\r\nand subglacial liquids. As part of the EnEx project, an initial concept study is foreseen for a\r\nlander mission to Enceladus to deploy the IceMole near one of the active water plumes on\r\nthe moon's South-Polar Terrain, where it will search for signatures of life.\r\nThe general mission concept is to place the Lander at a safe distance from an active\r\nplume. The IceMole would then be deployed to melt its way through the ice crust to an\r\naquiferous fracture at a depth of 100 m or more for an in situ examination for the presence\r\nof microorganisms.\r\nThe driving requirement for the mission is the high energy demand by the IceMole to\r\nmelt through the cold Enceladan ices. This requirement is met by a nuclear reactor\r\nproviding 5 kW of electrical power. The nuclear reactor and the IceMole are placed on a\r\npallet lander platform. An Orbiter element is also foreseen, with the main function of\r\nacting as a communications relay between Lander and Earth.\r\nAfter launch, the Lander and Orbiter will perform the interplanetary transfer to Saturn\r\ntogether, using the on-board nuclear reactor to power electric thrusters. After Saturn orbit\r\ninsertion, the Combined Spacecraft will continue using Nuclear Electric Propulsion to\r\nreach the orbit of Enceladus. After orbit insertion at Enceladus, the Orbiter will perform a\r\ndetailed reconnaissance of the South-Polar Terrain. At the end of the reconnaissance\r\nphase, the Lander will separate from the Orbiter and an autonomously guided landing\r\nsequence will place it near one of the active vapor plumes. Once landed, the IceMole will\r\nbe deployed and start melting through the ice, while navigating around hazards and\r\ntowards a target subglacial aquiferous fracture.\r\nAn initial estimation of the mission's cost is given, as well as recommendations on the\r\nfurther development of enabling technologies. The planetary protection challenges posed\r\nby such a mission are also addressed.    «

The plumes discovered by the Cassini mission emanating from the south pole of Saturn's\r\nmoon Enceladus and the unique chemistry found in them have fueled speculations that\r\nEnceladus may harbor life. The presumed aquiferous fractures from which the plumes\r\nemanate would make a prime target in the search for extraterrestrial life and would be\r\nmore easily accessible than the moon's subglacial ocean.\r\nA lander mission that is equipped with a subsurface maneuverable ice melting probe\r\nw...    »