Habitat-OASIS addresses the question of habitability of the outer solar system by looking at space craft data and preparing future space missions using novel approaches. The classical view held that a habitable planet or moon requires liquid water at or near its surface. This view has been challenged by the discovery of numerous subsurface oceans below the icy crusts of ice moons orbiting Jupiter and Saturn in the outer solar system. The amount of water detected there is several times higher than on Earth and is kept liquid not by solar heat but mostly by internal heating. Among them, the cryo-volcanic moons Enceladus at Saturn, and Europa which orbits Jupiter, are considered to have the largest astrobiological potential. On these two moons, the ocean floor is on top of a rocky core and there are indications for hydrothermal activities where hot water flows out from the rocky sea floor into the ocean. On Earth, these kinds of hydrothermal vents are places where life developed independently of sunlight.
It is apparent that the search for habitable places on our doorstep, inside our solar system, is important beyond the space science community and is relevant for the society in a more general sense. By understanding the habitability of icy ocean worlds, the ambitious ERC projects will translate to the habitability of the Universe in general, because icy moons orbiting giant planets should be fairly common in our galaxy. Consequently, this work will open up fundamental perspectives: if habitable conditions can occur at remote places like on ‘tiny’ Enceladus, we may have drastically underestimated the life-friendliness of our universe. Habitat-OASIS aims to explore the habitability of these worlds using in situ compositional data from current and future space missions.
On Enceladus (and probably also on Europa), the ice grains expelled by active plumes carry matter previously dissolved and suspended in the subsurface oceans, allowing constraining their geochemistry. The mass spectrometers aboard the Cassini-Huygens spacecraft orbiting Saturn until fall 2017 analyzed this material and already delivered spectacular science results. Project 1 of this proposal is the refined data analysis of the Enceladus plume material using novel techniques and is the first ever opportunity to explore in detail a potential ocean habitat outside Earth. Newly developed laser-assisted dispersion experiments are used to acquire mass spectra on a wide variety of analogue materials, enabling the identification and quantification of inorganic, organic and possibly biogenic compounds embedded in the ice grains. Geochemical aqueous alteration experiments and numerical modeling help to further constrain the habitability of Enceladus and extrapolate the results to other ocean moons. Project 2 will leverage the laboratory capabilities from Project 1 to create a comprehensive library of mass spectra in preparation of the upcoming missions visiting Jupiter’s icy moons: ESA’s JUICE Mission and NASA’s Europa Clipper Mission. Having analogue measurements available early in the missions will be critical for exploiting their full potential.
