Feasibility of Detecting Bioorganic Compounds in Enceladus Plumes with the Enceladus Organic Analyzer

Abstract

Enceladus presents an excellent opportunity to detect organic molecules that are relevant for habitability as well as bioorganic molecules that provide evidence for extraterrestrial life because Enceladus' plume is composed of material from the subsurface ocean that has a high habitability potential and significant organic content. A primary challenge is to send instruments to Enceladus that can efficiently sample organic molecules in the plume and analyze for the most relevant molecules with the necessary detection limits. To this end, we present the scientific feasibility and engineering design of the Enceladus Organic Analyzer (EOA) that uses a microfluidic capillary electrophoresis system to provide sensitive detection of a wide range of relevant organic molecules, including amines, amino acids, and carboxylic acids, with ppm plume-detection limits (100 pM limits of detection). Importantly, the design of a capture plate that effectively gathers plume ice particles at encounter velocities from 200 m/s to 5 km/s is described, and the ice particle impact is modeled to demonstrate that material will be efficiently captured without organic decomposition. While the EOA can also operate on a landed mission, the relative technical ease of a fly-by mission to Enceladus, the possibility to nondestructively capture pristine samples from deep within the Enceladus ocean, plus the high sensitivity of the EOA instrument for molecules of bioorganic relevance for life detection argue for the inclusion of EOA on Enceladus missions. Key Words: Lab-on-a-chip—Organic biomarkers—Life detection—Planetary exploration. Astrobiology 17, 902–912.

Characterizing organic particle impacts on inert metal surfaces: Foundations for capturing organic molecules during hypervelocity transits of Enceladus plumes

“…Our overall goal is to explore the feasibility of flying through the ice plumes at Enceladus and gathering sufficient ice particles that we can perform a sensitive analysis for unmodified organic biomarkers using, for example, the EOA (Mathies et al. ). It is thus important to understand the nature of particle impacts on different target materials, to understand how the impacts change with velocity and particle size, to identify the optimal material for particle capture, and to ascertain the organic survival of ice‐particle simulants postimpact.…”

“…Inert metal target foils of Ag, Al, Au, Cu, and In were identified as potentially compliant capture materials that meet the science and engineering requirements of the EOA capture system (Mathies et al. ). In particular, we desire a compliant material that more gradually slows the impacting particle and creates a crater to capture the residue.…”

“…This work forms part of a project developing the Enceladus Organic Analyzer (EOA) instrument for probing biosignatures in icy plumes (Mathies et al. ).…”

Could It Be Snowing Microbes on Enceladus? Assessing Conditions in Its Plume and Implications for Future Missions

“…A concentration at this level would yield, in a single transect of the average plume at 50 km, ∼1 nL of organic material on a 0.04 m 2 collecting plate. Though meager, these amounts are easily detectable by present-day, post-Cassini mass spectrometers (Lunine et al, 2015 ) and microfluidics instruments that measure chirality (Mathies et al, 2017 , in this issue) in a single transect through the plume.…”

Exo-Ocean Exploration with Deep-Sea Sensor and Platform Technologies

“…Additionally, the use of Lab-on-a-Chip (LOC) technologies should be advanced to facilitate miniaturized time-series measurements on those platforms (Beaton et al, 2012). LOC could be used to trace metabolic products, based on the detection of free-circulating compounds through specifically designed markers, as suggested by Cassini-Huygens' recompiled information (Mathies et al, 2017).…”