The Search for Life on Mars

Yoshimura, Yoshitaka

doi:10.1007/978-981-13-3639-3_23

Cited by 5 publications

(4 citation statements)

References 79 publications

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“…Fluorescence microscopes are thought to be viable research instruments for extraterrestrial life [15][16][17][18][19][20]. Their targeted sensitivity limit is ~10 4 cells/g of soil; therefore, the results described above suggest that the sensitivity of the culture reported in this work was higher than that of a fluorescence microscope.…”

Section: Comparisons With Microscopymentioning

confidence: 70%

Cell culture experiment using a Mars soil simulant for the detection of extraterrestrial life

Enya

Sasaki

Fujishiro

et al. 2023

SPIE Future Sensing Technologies 2023

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We describe a cell culture experiment utilizing Mars soil simulant and yeast as a study for extraterrestrial-microorganism detection in future. The following conditions were combined to create different sample configurations: solid medium (agar plate) or liquid medium, with the Mars soil simulant (100 mg) or without, and various yeast cell densities (30 μL of a suspension of yeast prepared to achieve dilution rates of 10 −2 , 10 −3 , 10 −4 , and 10 −5 from the original suspension). For redundancy, two samples were created for each setting. On each agar plate, colonies of yeast cells were visible. In contrast, only samples created with a dilution rate of 10 −2 and 10 −3 were proven to show the presence of yeast proliferating in liquid media. The agar plates were observed via imaging using a digital camera. Colony counting was conducted using functions of the ImageJ software; the yeast density in the original suspension was estimated to be 2.5 × 10 7 colony forming units (CFU)/mL. Based on the results of cell culture on the agar plates, the detection limit that was experimentally demonstrated in this work amounted to 7.5 CFU/100 mg of soil, which corresponded to 75 CFU/g of soil. Thus, we confirmed that the Mars soil simulant reduced the number of colonies to one-third of that detected without the Mars soil simulant. In the discussion, we pointed out that the method that used the solid media has potential to provide high sensitivity using a simple, compact, and lightweight hardware. Microscope with no optics is also discussed. The lower limit of detection obtained in this study was compared with those obtained using other methods. We compared and discussed extraterrestrial life search based on (1) in situ experiments by unmanned missions, (2) analysis of samples returned to Earth, and (3) dedicated in situ analyses by manned bases located on extraterrestrial sites in the future. The perspectives discussed herein are applicable not only to the samples from Mars but also to the samples from other solar system bodies. Identifying cell culture conditions for these applications is a critical difficulty. Notably, it is a possible scenario that cell culture (although challenging) will become necessary to obtain clear evidence of extraterrestrial life. We also note that in cases where there are multiple species of microorganisms, it can happen that microorganisms that fit the culture conditions used in an experiment are selectively cultured and detected, even if the culture conditions for each species are not fully discovered. It is worthwhile to conduct exploration in advance designed with the intention of determining culture conditions with the plan to culture microorganisms in the future.

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Section: Comparisons With Microscopymentioning

confidence: 70%

Cell culture experiment using a Mars soil simulant for the detection of extraterrestrial life

Enya

Sasaki

Fujishiro

et al. 2023

SPIE Future Sensing Technologies 2023

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“…A fluorescence microscope is considered to be one of the promising tool for search and analysis for extraterrestrial life [16][17][18], in which targeted sensitivity limit is ~ 10 4 cells g −1 soil. This target is set based on studies for microorganism density of Atacama Desert where is considered as one of the place where microorganism density is the lowest on the earth [19][20][21][22][23].…”

Section: Discussionmentioning

confidence: 99%

Laboratory experiment of ATP measurement using Mars soil simulant: as a method for extraterrestrial life detection

Enya

Sasaki

2022

ANAL. SCI.

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We present a laboratory experiment of ATP measurement using Mars soil simulant and Escherichia coli (E. coli) with a point of view for future application to searching extraterrestrial life. We used Mars Global Simulant MGS-1 (Exolith Lab) as soil simulant, added E. coli suspension to it, then the soil simulant with E. coli was dried. Various configurations of samples with different E. coli density, 1.75 × 102, 1.75 × 103, 1.75 × 104, 1.75 × 105, and 1.75 × 106 cells (g soil)−1, were prepared together with controls. ATP extraction reagent and luminescence reagent were added to the sample, and bioluminescence measurement was performed. The result suggests significant detection of ATP for samples with E. coli density used in this work. Similar experiments but without the soil simulant were carried out, and results with and without the soil simulant are compared. Based on the ATP measurement studied in this work, we discussed extraterrestrial life search, planetary protection, relation with the panspermia hypothesis, and also other applications. Graphical abstract

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“…A variety of redox energy couples would have been available on early Mars [226,227], in addition to the solar sources of ultraviolet and visible energy. The reduction in the amount of CO 2 to organics by H 2 is an exergonic reaction and methanogenesis is considered a likely early metabolism.…”

Section: Energy Sources On Marsmentioning

confidence: 99%

Origin of Life on Mars: Suitability and Opportunities

Clark

Kolb

Steele

et al. 2021

Life

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Although the habitability of early Mars is now well established, its suitability for conditions favorable to an independent origin of life (OoL) has been less certain. With continued exploration, evidence has mounted for a widespread diversity of physical and chemical conditions on Mars that mimic those variously hypothesized as settings in which life first arose on Earth. Mars has also provided water, energy sources, CHNOPS elements, critical catalytic transition metal elements, as well as B, Mg, Ca, Na and K, all of which are elements associated with life as we know it. With its highly favorable sulfur abundance and land/ocean ratio, early wet Mars remains a prime candidate for its own OoL, in many respects superior to Earth. The relatively well-preserved ancient surface of planet Mars helps inform the range of possible analogous conditions during the now-obliterated history of early Earth. Continued exploration of Mars also contributes to the understanding of the opportunities for settings enabling an OoL on exoplanets. Favoring geochemical sediment samples for eventual return to Earth will enhance assessments of the likelihood of a Martian OoL.

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The Search for Life on Mars

Cited by 5 publications

References 79 publications

Cell culture experiment using a Mars soil simulant for the detection of extraterrestrial life

Cell culture experiment using a Mars soil simulant for the detection of extraterrestrial life

Laboratory experiment of ATP measurement using Mars soil simulant: as a method for extraterrestrial life detection

Origin of Life on Mars: Suitability and Opportunities

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