Searching for Life in an Ocean World: The Enceladus Life Signatures and Habitability (ELSAH) mission concept
The Enceladus Life Signatures and Habitability (ELSAH) mission concept aims to directly sample the plume of Enceladus, a moon of Saturn, to search for evidence of life and to assess the habitability of its subsurface ocean. It was proposed to New Frontiers 4 in 2017 and was judged selectable. ELSAH was awarded technology development funding to develop cost-effective techniques that limit spacecraft contamination and thereby enable life detection measurements on cost-capped missions.Through repeated flythroughs of the plume, the Cassini Mission has shown that the ice particles originate from a interior ocean, that the ocean is slightly salty, that hydrothermal activity is occurring and water is in contact with rock, that organic material, sulfur and nitrogen are present in forms that can be used by biology, and that there are chemical energy sources that on Earth can sustain metabolic activity. ELSAH flies to Enceladus to follow up on these exciting discoveries, and to determine if life is present in the ocean. As the spacecraft flies through the plume, it will collect ice particles and then melt them. The resulting liquid sample will then be delivered to the analytical instruments that are capable of identifying four key life signatures: 1) relative concentrations of proteinogenic amino acids, 2) amino acid enantiomeric excess, 3) lipid molecular patterns, and 4) lipid distributions. Together these four measurements will be used to assess if ocean life is present on Enceladus and its signatures are found in the plume particulates. The same measurements will also support the detection of abiotic signatures, assessing the role that cometary and meteoritic material may be directly contributing to the organics in the plume. In addition, ELSAH will measure properties of the ice-water plume particles (pH, salinity, etc.) to further understand the habitability of the ocean and corroborate Cassini findings. Imagers will document surface and vent features on Enceladus to further our understanding of plume sources.The Enceladus ocean may be the most characterized habitable environment for extant life beyond Earth known today and the Enceladus plume is beckoning as a door of opportunity for us to study its ocean without having to land or drill through the ice cover. ELSAH builds on these prospects to address NASA's goal to search for life in our Solar System and open a new frontier in space science.
42nd COSPAR Scientific Assembly
- Pub Date:
- July 2018