SCHAN: Life Detection and Organic Analysis at Mars and Ocean Worlds with Supercritical CO2 and Subcritical H2O

Future robotic missions to Mars and Ocean Worlds will require lower detection limits and improved ruggedness for in-situ life detection and analysis of organic inventory. Current techniques based on thermal volatilization and derivatization (e.g., gas chromatography) can be adversely affected by oxidative species (e.g., perchlorates) and minerals. Here, we report on the design and development of an integrated and miniaturized system, which includes sample handling, extraction, preconcentration, separation, and detection for solid samples (e.g., Mars) and water ice (e.g., Enceladus), including the latest validation results from testing in a relevant environment (low temperature and vacuum). The core sample processing subsystem, the Supercritical CO2 and Subcritical H2O Analysis (SCHAN) instrument, utilizes methods developed to reduce the risks of degradation, alteration, and contamination by using lower temperatures (≤250 °C), only water and supercritical carbon dioxide as solvents, and circumventing the use of derivatization reagents. We have demonstrated lower limits of detection down to 20 pg/g (parts-per-trillion) for lipids, 25 pg/g for chiral amino acids, and 10^4 cells/mL with an integrated cell lysis protocol based on supercritical CO2, corresponding to approximately ≥3 orders of magnitude improved lower limits of detection than previously flown instruments. The front-end Sample Handling and Distribution (SHaD) subsystem for Enceladus-type missions has been demonstrated in tandem with the SCHAN instrument by analyzing both liquid and ice samples. A multi-chamber carousel version is being built to handle supercritical fluid extraction up to 22 MPa and 200 °C for Mars applications. The back-end detection subsystem, with heritage from JPL's Quadrupole Ion Trap Mass Spectrometer (QTIMS), is being developed to be coupled with the SCHAN instrument to detect high-priority organic biosignatures.