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The cause of the cryovolcanic activity on the Enceladus south hemisphere and related to this activity gas plumes are one of the biggest mysteries of the outer solar system moons. The possibility of the existence of the ocean under Enceladus icy outer layer was confirmed through direct chemical plumes composition measurement during Cassini close flyby 168.2 km over moon’s surface. Three out of the four main plumes components are standard biomarkers (H2O, CO2 and CH4). Physical plumes parameters variability observed also by Cassini, possibility of drawing conclusions about cryovolcanic activity reasons and biotic causes of biomarkers presence in plumes are important reasons of new, dedicated to Enceladus observation, NASA’s mission development. In this paper we are asking about possibility of Enceladus plumes chemical components analysis using multispectral imaging by projected for this new mission sensors. We chose band 0.73 μm for H2O and CO2 distinguish using theoretical transmittance gas layers analysis and physical radiation transmittance through gas layer visible on the background material with defined constant reflectance model. In order to validate this result an experiment was conducted. Using multispectral camera Quercus.6 we photographed H2O and CO2 gas layers visible on the high (> 0.95) and low (< 0.05) visible light and NIR reflectance backgrounds. The results confirmed theoretical spectral transmittance analysis of those two biomarkers. Based on this result we established boundary parameters of the sensor and optical system projected for the orbiter allowing relative content of the biomarkers estimation with precision up to 2%: optical band λ = 0.730 (± 0.020) μm, relative velocity between orbiter and moon v < 200 m/s, exposition time tEXP < 12 ms, quantum efficiency of the whole optical system and two biomarkers in selected wavelength reflectance difference product ≥ 2,5%, single CCD pixel physical size ≥ (3,75 · 3,75) μm2, potential well depth for one CCD pixel ≥ 12 400 e–, RAW data record at least 8-bit. Optimal result waveband wasn’t recorded before using MVIC optical systems during past missions. If we want to apply proposed in this paper biomarkers distinguish methodology one out of four optical channels of the MAC camera projected for the new mission should cover also selected wavelength.

Detection of Biomarkers in Gas Plumes Using a Multi-Spectral Camera in the Proposed Enceladus Orbiter Mission (NASA)