Contamination Control for Ultra-Sensitive Life-Detection Missions

Abstract

A key science priority for planetary exploration is to search for signs of life in our Solar System. Life-detection mission concepts aim to assess whether or not biomolecular signatures of life are present, which requires highly sensitive instrumentation. This introduces greater risk of false positives, and perhaps false negatives. Stringent science-derived contamination requirements for achieving science measurements on life-detection missions necessitate mitigation approaches that minimize, protect from, and prevent science-relevant contamination of critical surfaces of the science payload and provide high confidence to life-detection determinations. To this end, we report on technology advances that focus on understanding contamination transfer from pre-launch processing to end of mission using high-fidelity physics in the form of computational fluid dynamics and sorption physics for monolayer adsorption/desorption, and on developing a new full-spacecraft bio-molecular barrier design that restricts contamination of the spacecraft and instruments by the launch vehicle hardware. The bio-molecular barrier isolates the spacecraft from biological, molecular, and particulate contamination from the external environment. Models were used to evaluate contamination transport for a designs reference mission that utilizes the barrier. Results of the modeling verify the efficacy of the barrier and an in-cruise decontamination activity. Overall mission contamination tracking from launch to science operations demonstrated exceptionally low probability on contamination impacting science measurements, meeting the stringent contamination requirements of femtomolar levels of compounds. These advances will enable planetary missions that aim to detect and identify signatures of life in our Solar System.

Solid-State Single-Molecule Sensing with the Electronic Life-detection Instrument for Enceladus/Europa (ELIE)

“…Improving levels of detection towards single-molecule detection, in the pico-to femtomoles range, remains an ongoing goal for in-situ life-detection technologies. This is a significant issue because signatures of life or abiotically produced organics in other planetary bodies across our Solar System may be present at exceedingly low abundances, or only accessible in low abundances (Eigenbrode et al 2021). Here, we demonstrate that the use of nanogap systems show great potential in this critical regard by performing as ultra-sensitive agnostic detectors without sacrificing the capacity to discriminate among molecules or chemical moieties (such as between different amino acids or DNA bases).…”

“…Improving levels of detection towards single-molecule detection, in the pico-to femtomoles range, remains an ongoing goal for in-situ life-detection technologies. This is a significant issue because signatures of life or abiotically produced organics in other planetary bodies across our Solar System may be present at exceedingly low abundances, or only accessible in low abundances (Eigenbrode et al . 2021).…”

Science Objectives for Flagship-Class Mission Concepts for the Search for Evidence of Life at Enceladus

“…Contamination must be controlled down to, in some cases, molecular levels to avoid interfering with analyses of samples. Given the low abundance of compounds of interest expected at Enceladus, and given the sensitivity of the analytical payload, the requirements to control molecular contamination are likely more stringent than the requirements imposed on bioburden levels, and they will also require cleaning and validation strategies that are different from those employed to limit bioburden (Eigenbrode et al , 2021 ).…”

“…Contamination control would have to be an integral part of the design of a mission such as Orbilander through all mission phases. Possible contamination control strategies include, in addition to the assembly of parts and payload elements in ultra-clean rooms, the use of a full spacecraft barrier, and on-cruise bake-out of critical surfaces ( e.g ., the sample acquisition systems), both of which have proven efficient at reducing particle and molecular contamination by a factor of 10 −3 and 10 −1 , respectively (Eigenbrode et al , 2021 ).…”

Chirality in Organic and Mineral Systems: A Review of Reactivity and Alteration Processes Relevant to Prebiotic Chemistry and Life Detection Missions

“…Habitability and life detection missions commonly need to address issues related to contamination and outgassing in accordance with guidelines suggested by the International Committee on Space Research (COSPAR) for planetary protection (e.g., [48,511,512]). Missions and proposed mission concepts that address contamination control issues are typically or wholly concerned with adhering to the requirements set out by planetary protection (PP) guidelines, through verification and quantification of bioburden on instrument and spacecraft surfaces.…”