Electronic Life-detection Instrument for Enceladus/Europa (ELIE)

Background: Widespread synthesis of complex organics, including nucleobases, amino acids, and sugars, occurred early in the history of the solar system, in the solar nebula. These organics were delivered by comets and meteorites to multiple potentially habitable zones (e.g., Earth, Mars, Enceladus, Europa, Titan), which may be targeted by future missions in the search for extant life beyond Earth, e.g., Ocean Worlds. Even in the absence of common ancestry (Panspermia), common building blocks and similar physicochemical environments could have resulted in independent origins of life based on similar biochemistry. We target not only single amino acids (and abundance distribution) but also information-rich biogenic organic molecules: charged linear informational polymers (IPs), enabled by recent advances in solid-state single-molecule nanogap sensors (via quantum electron tunneling, QET). Science Goals: Our mission is to develop an instrument, the Electronic Life-detection Instrument for Enceladus/Europa (ELIE), capable of detecting prebiotic, ancient, or extant life, and distinguishing forward contamination, through detection of two universal biomarkers: the amino acid abundance distribution and IPs. Our instrument will be quite versatile and suitable for a multitude of missions, including lander, rover, subsea explorer, and plume-fly-through missions to Mars, Enceladus, Europa, and other Ocean Worlds. Furthermore, by quantifying forward contamination, our instrument will be able to identify false positives and support planetary protection. Objectives: We will validate single molecule nanogap detection and develop a breadboard system to advance ELIE from technology readiness level (TRL) 2 to TRL 4 and a plan to achieve TRL 6 by the Preliminary Design Review of an Ocean World mission such as Europa Lander or a New Frontiers Enceladus mission. Methodology: An existing nanogap system, already validated on single amino acids, RNA, and DNA, will be used to test first pure solutions, then mixtures of increasing fidelity, such as a protocell and B. subtilis spores in Ocean World analog solutions, prior to validation on environmental analog samples. Comparisons of yield and sensitivity will be made to existing life detection instruments as well as to single molecule sequencing (MinION) and a solid state nanopore, enabled by common low noise amplifier hardware of a proposed TRL 4 system. This system will also integrate a pre-concentration step to target 10 ppt sensitivity for amino acids. Nanogaps have sub-nanometer adjustable gap spacing to accommodate different sizes of molecules. Machine learning methods will be applied to classify biomolecules. The lack of biological reagents supports planetary protection goals by permitting bioburden reduction. Relevance: Our effort specifically responds to multiple aspects of the PICASSO solicitation including "characterize potential biopolymers," "detect chemical processes indicative of potential life," and "detect ultralow concentrations of microorganisms." We propose a sensitive and information rich approach to detection of life beyond Earth, suitable for future deployment on multiple missions.