LDM (Life Detection Microscope): In Situ Imaging of Living Cells on Surface of Mars

Abstract

The Life Detection Microscope (LDM) is the instrument to take microscopic images of powder samples on Mars surface. The LDM is designed to use fluorescence pigments to detect organic compounds and those surrounded by membrane, and then to test the esterase catalytic activity to detect metabolic reaction, as well as to take microscopic images of regolith and dust particles. The LDM has high resolution to resolve terrestrial prokaryotes (primitive microorganism), 1 μm/pixel, and high sensitivity, 10 4 "cells" per gram powder, by inspecting sufficient, 1 mm 3 , volume of powder sample. We propose to conduct extant, not only past, life search program on Mars surface.

In situ biochemical characterization of Venus cloud particles using a life-signature detection microscope

“…Toward the development of the Mars LDM, Yamagishi et al proposed a staining system that enables (1) the detection of organic compounds, including those of abiotic origin such as polycyclic aromatic hydrocarbons (PAHs); (2) the highlighting of biotic organic compounds seen inside cells; and (3) the detection of products of catalytic D r a f t reactions (Yamagishi et al 2016(Yamagishi et al , 2018. In experiments with the Mars LDM, SYTO 24, propidium iodide (PI), SYPRO Red, and CFDA-AM are used as pigments.…”

“…In experiments with the Mars LDM, SYTO 24, propidium iodide (PI), SYPRO Red, and CFDA-AM are used as pigments. Using E. coli live cells, E. coli dead cells, miniature E. coli live cells without DNA, miniature E. coli dead cells without DNA, protein (bovine serum albumin, BSA), and PAHs as biological materials, it is possible to tell whether fluorescent objects in the field of view are live cells, dead cells, or protein/PAHs when a set of pigments (SYTO 24 or SYPRO Red, PI, and CFDA-AM) is used (Yamagishi et al 2018;Yoshimura et al 2020). It is also reported that SYTO 24 and PI can stain cells in the presence of 2% hyperchloride or after the irradiation of 80 Gy gamma ray or after heat treatment at 70°C (Yamagishi et al 2018).…”

“…The Venus LDM is based partly on the Mars Life-signature Detection Microscope (Mars LDM) (Yamagishi et al 2016(Yamagishi et al , 2018. The Mars LDM is designed to detect life signatures by searching for cell-like structures in a sample of the Martian regolith, which is transported and introduced to the LDM by a robotic arm installed on the rover harboring the LDM.…”

“…As mentioned before, a fluorescent staining system has been designed to distinguish biotic organic compounds from abiotic ones (Yamagishi et al 2016(Yamagishi et al , 2018. This system can highlight biotic organic compounds surrounded by a membrane, with 1 μm/pixel resolution, which is essential for resolving the structure of terrestrial microbial cells.…”

Venus, an Astrobiology Target

“…Organic hazes with fractal shapes rather than spherical shaped particles have been suggested for Titan (Rannou et al, 1997;Wolf and Toon, 2010) and primitive Earth (Arney et al, 2016). Images of the aerosols with a microscope (Yamagishi et al, 2016;Sasaki et al, 2019) would help settle the question of the identity of the large aerosols. To date, aerosol size populations have been inferred from in situ backscattering (Ragent and Blamont, 1980), the glory feature at the cloud tops (Markiewicz et al, 2014), polarization data (Kawabata et al, 1980(Kawabata et al, , 1986Sato et al, 1996;Rossi et al, 2015), and from forward scattering (Wilquet et al, 2012), but no direct measurements have been made.…”