Microscope for Life-signature Detection in Venus Cloud

The usefulness of life-signature detection instruments has been proposed for the missions on astrobiology with aerial platforms. To obtain visible images of particles and to search for the life signature including possible "cells" in the Venus cloud samples, a Life-signiture Detection Microscope (LDM) have been developed. As backgrounds, although Venus clouds consist of droplets of 75-85% sulfuric acidic-water [1], the sulfuric acid is not sufficient to explain the observed albedo and cloud contrasts of the planet Venus. It has been indicated that the contribution of other chemical species involved in the absorption [2]. Evolution and emergence of sulfur-metabolizing or thermophilic bacteria have been postulated [3], together with the presence of active volcanos suggested on Venus, [4] and the possible existence of the past liquid water. Besides the planet surface being too extreme for living organism and organic compound to survive, the temperature and pressure are moderate several tens km above surface on Venus. The presence of microorganisms is, therefore, suspected in the clouds [4] that might contribute to the spectroscopic characteristics. The stains that can distinguish abiotic organic compounds from biotic ones are now being tested to function under the acidic conditions similar to the Venus cloud environment. Detaction of both organic compounds surrounded by membrane representing "cells", and metabolism in the typical cells of terrestrial life [5] [6] are expected using our system. 1 micrometer/pixel resolution of the system fulfills the requirements for the observation of almost all microbes on earth. Our LDM system should fit for Aerial platforms such as Venus Atmospheric Mobile Platform [7] to analyze the aerosol. References: [1] Travis, L.D. (1975) J. Atmospheric Sci., 32, 1190-1200. [2] Pollack, J.B. et al. (1980) J. Geophys. Res., 85, 8141-8150. [3] Limaye, S. S., et al. (2018). Venus' Spectral Signatures and the Potential for Life in the Clouds. Astrobiology, 18, 1181-1198. [4] Shalygin, E.V. et al. (2015) Geophys. Res. Lett., 42, 4762-4769. [5] Yamagishi, A. et al. (2010) Biol. Sci. Space, 24, 67-82. [6] Yamagishi, A., et al. (2018) Trans. JSASS Aerospace Tech. Japan, 16, 299-305. [7] Lee, G., et al. (2015a) [abstract id.P23A-2109]. American Geophysical Union, Fall Meeting.