Subsurface exolife

Lingam, Manasvi; Loeb, Abraham

doi:10.1017/s1473550418000083

Cited by 41 publications

(31 citation statements)

References 576 publications

(722 reference statements)

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“…Yet, many of the critical step models discussed in the literature take it for granted that the evolution of humans constitutes the last critical step regardless of the duration of the habitable period of the Earth.8 Thus, we shall not focus on habitable worlds outside the HZ, which are expected to be much more commonplace compared to those within the HZ(Lingam and Loeb, 2018g).…”

mentioning

confidence: 99%

Role of stellar physics in regulating the critical steps for life

Lingam

Loeb

2019

International Journal of Astrobiology

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We use the critical step model to study the major transitions in evolution on Earth. We find that a total of five steps represents the most plausible estimate, in agreement with previous studies, and use the fossil record to identify the potential candidates. We apply the model to Earth-analogs around stars of different masses by incorporating the constraints on habitability set by stellar physics including the habitable zone lifetime, availability of ultraviolet radiation for prebiotic chemistry, and atmospheric escape. The critical step model suggests that the habitability of Earth-analogs around M-dwarfs is significantly suppressed. The total number of stars with planets containing detectable biosignatures of microbial life is expected to be highest for Kdwarfs. In contrast, we find that the corresponding value for intelligent life (technosignatures) should be highest for solar-mass stars. Thus, our work may assist in the identification of suitable targets in the search for biosignatures and technosignatures.

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confidence: 99%

Role of stellar physics in regulating the critical steps for life

Lingam

Loeb

2019

International Journal of Astrobiology

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“…The potential habitability of icy moons has led to studies addressing possible microbial survival and growth [17][18][19][20][21][22], as well as estimates of biomass concentrations [23][24][25] in these environments. The results show that, under certain conditions (degree of convection, mantle rheology, etc.…”

Section: Of 12mentioning

confidence: 99%

Towards Determining Biosignature Retention in Icy World Plumes

Bywaters

Stoker

Nascimento

et al. 2020

Life

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With the discovery of the persistent jets of water being ejected to space from Enceladus, an understanding of the effect of the space environment on potential organisms and biosignatures in them is necessary for planning life detection missions. We experimentally determine the survivability of microbial cells in liquid medium when ejected into vacuum. Epifluorescence microscopy, using a lipid stain, and SEM imaging were used to interrogate the cellular integrity of E. coli after ejected through a pressurized nozzle into a vacuum chamber. The experimental samples showed a 94% decrease in visible intact E. coli cells but showed a fluorescence residue in the shape of the sublimated droplets that indicated the presence of lipids. The differences in the experimental conditions versus those expected on Enceladus should not change the analog value because the process a sample would undergo when ejected into space was representative. E. coli was selected for testing although other cell types could vary physiologically which would affect their response to a vacuum environment. More testing is needed to determine the dynamic range in concentration of cells expected to survive the plume environment. However, these results suggest that lipids may be directly detectable evidence of life in icy world plumes.

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“…We can tentatively assume that stellar encounters, although more frequent, do not present special concerns in the bulge with respect to the disk. Anyway, we point out that assessing the habitability conditions in the bulge is not limited to planets in bound orbits around a host star: it would be relevant also for possible rogue, free-floating planets that may host life, for example below an icy surface [43,44].…”

Section: Orbital Stability and Encountersmentioning

confidence: 99%

The Habitability of the Galactic Bulge

Balbi

Hami

Kovačević

2020

Life

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We present a new investigation of the habitability of the Milky Way bulge, that expands previous studies on the Galactic Habitable Zone. We discuss existing knowledge on the abundance of planets in the bulge, metallicity and the possible frequency of rocky planets, orbital stability and encounters, and the possibility of planets around the central supermassive black hole. We focus on two aspects that can present substantial differences with respect to the environment in the disk: (i) the ionizing radiation environment, due to the presence of the central black hole and to the highest rate of supernovae explosions and (ii) the efficiency of putative lithopanspermia mechanism for the diffusion of life between stellar systems. We use analytical models of the star density in the bulge to provide estimates of the rate of catastrophic events and of the diffusion timescales for life over interstellar distances.

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Subsurface exolife

Cited by 41 publications

References 576 publications

Role of stellar physics in regulating the critical steps for life

Role of stellar physics in regulating the critical steps for life

Towards Determining Biosignature Retention in Icy World Plumes

The Habitability of the Galactic Bulge

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