The Production of Oxidants in Europa's Surface

Johnson, R. E.; Quickenden, T. I.; Cooper, Paul D.; McKinley, Allan J.; Freeman, Colin G.

doi:10.1089/153110703322736123

Cited by 78 publications

(75 citation statements)

References 87 publications

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“…Gaidos et al (1999) suggested that life in sealed oceans under thick ice cover would rapidly die out due to depletion of redox pairs. Gaidos et al (1999) been proposed that oxidants produced by radiation on the surface of the icy satellites could be carried to subsurface liquid water reservoirs that may contain reductants (Chyba and Phillips, 2001;Johnson et al, 2003;Cooper et al, 2007;Hand et al, 2007;Moore et al, 2007). Parkinson et al (2007Parkinson et al ( , 2008 considered Enceladus and argued for a similar, strong source of surface oxidants there.…”

Section: Possible Ecosystems On Enceladusmentioning

confidence: 99%

The Possible Origin and Persistence of Life on Enceladus and Detection of Biomarkers in the Plume

et al. 2008

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The jets of icy particles and water vapor issuing from the south pole of Enceladus are evidence for activity driven by some geophysical energy source. The vapor has also been shown to contain simple organic compounds, and the south polar terrain is bathed in excess heat coming from below. The source of the ice and vapor, and the mechanisms that accelerate the material into space, remain obscure. However, it is possible that a liquid water environment exists beneath the south polar cap, which may be conducive to life. Several theories for the origin of life on Earth would apply to Enceladus. These are (1) origin in an organic-rich mixture, (2) origin in the redox gradient of a submarine vent, and (3) panspermia. There are three microbial ecosystems on Earth that do not rely on sunlight, oxygen, or organics produced at the surface and, thus, provide analogues for possible ecologies on Enceladus. Two of these ecosystems are found deep in volcanic rock, and the primary productivity is based on the consumption by methanogens of hydrogen produced by rock reactions with water. The third ecosystem is found deep below the surface in South Africa and is based on sulfur-reducing bacteria consuming hydrogen and sulfate, both of which are ultimately produced by radioactive decay. Methane has been detected in the plume of Enceladus and may be biological in origin. An indicator of biological origin may be the ratio of non-methane hydrocarbons to methane, which is very low (0.001) for biological sources but is higher (0.1-0.01) for nonbiological sources. Thus, Cassini's instruments may detect plausible evidence for life by analysis of hydrocarbons in the plume during close encounters.

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Section: Possible Ecosystems On Enceladusmentioning

confidence: 99%

The Possible Origin and Persistence of Life on Enceladus and Detection of Biomarkers in the Plume

et al. 2008

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“…Houtkooper and Schulze-Makuch (2007) suggested that hypothetical martian organisms might use a H 2 O 2 -H 2 O mixture as an intracellular fluid to be optimally adapted to the highly oxidized martian environment. Moreover, it has been reported that the surface of Europa, the icy satellite of Jupiter, contains H 2 O 2 , and both radiolysis and photolysis of its icy surface leads to the formation of oxygen and ROS (Carlson et al, 1999;Johnson et al, 2003). Recently, the presence of abiotically formed O 2 has also been found in the atmosphere of Saturn's icy moon Rhea (Teolis et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Oxygen and Hydrogen Peroxide in the Early Evolution of Life on Earth:In silicoComparative Analysis of Biochemical Pathways

Ślesak

Kruk

2012

Astrobiology

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In the Universe, oxygen is the third most widespread element, while on Earth it is the most abundant one. Moreover, oxygen is a major constituent of all biopolymers fundamental to living organisms. Besides O 2 , reactive oxygen species (ROS), among them hydrogen peroxide (H 2 O 2 ), are also important reactants in the present aerobic metabolism. According to a widely accepted hypothesis, aerobic metabolism and many other reactions/pathways involving O 2 appeared after the evolution of oxygenic photosynthesis. In this study, the hypothesis was formulated that the Last Universal Common Ancestor (LUCA) was at least able to tolerate O 2 and detoxify ROS in a primordial environment. A comparative analysis was carried out of a number of the O 2 -and H 2 O 2 -involving metabolic reactions that occur in strict anaerobes, facultative anaerobes, and aerobes. The results indicate that the most likely LUCA possessed O 2 -and H 2 O 2 -involving pathways, mainly reactions to remove ROS, and had, at least in part, the components of aerobic respiration. Based on this, the presence of a low, but significant, quantity of H 2 O 2 and O 2 should be taken into account in theoretical models of the early Archean atmosphere and oceans and the evolution of life. It is suggested that the early metabolism involving O 2 /H 2 O 2 was a key adaptation of LUCA to already existing weakly oxic zones in Earth's primordial environment.

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“…It is noted that liquid hydrogen peroxide was not used during assembly of MSL as a microbial reduction method. Interestingly, it is reported that the surface ice of Europa contains as much as 0.13% hydrogen peroxide generated from the radiolysis of ice (Johnson et al, 2003). Microorganisms traveling to, and surviving on, distant planetary bodies like Europa would need to protect themselves from strong oxidants such as hydrogen peroxide.…”

Section: Discussionmentioning

confidence: 99%

Identification and Characterization of Early Mission Phase Microorganisms Residing on the Mars Science Laboratory and Assessment of Their Potential to Survive Mars-like Conditions

et al. 2017

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Planetary protection is governed by the Outer Space Treaty and includes the practice of protecting planetary bodies from contamination by Earth life. Although studies are constantly expanding our knowledge about life in extreme environments, it is still unclear what the probability is for terrestrial organisms to survive and grow on Mars. Having this knowledge is paramount to addressing whether microorganisms transported from Earth could negatively impact future space exploration. The objectives of this study were to identify cultivable microorganisms collected from the surface of the Mars Science Laboratory, to distinguish which of the cultivable microorganisms can utilize energy sources potentially available on Mars, and to determine the survival of the cultivable microorganisms upon exposure to physiological stresses present on the martian surface. Approximately 66% (237) of the 358 microorganisms identified are related to members of the Bacillus genus, although surprisingly, 22% of all isolates belong to non-spore-forming genera. A small number could grow by reduction of potential growth substrates found on Mars, such as perchlorate and sulfate, and many were resistant to desiccation and ultraviolet radiation (UVC). While most isolates either grew in media containing ‡10% NaCl or at 4°C, many grew when multiple physiological stresses were applied. The study yields details about the microorganisms that inhabit the surfaces of spacecraft after microbial reduction measures, information that will help gauge whether microorganisms from Earth pose a forward contamination risk that could impact future planetary protection policy.

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The Production of Oxidants in Europa's Surface

Cited by 78 publications

References 87 publications

The Possible Origin and Persistence of Life on Enceladus and Detection of Biomarkers in the Plume

The Possible Origin and Persistence of Life on Enceladus and Detection of Biomarkers in the Plume

Oxygen and Hydrogen Peroxide in the Early Evolution of Life on Earth:In silicoComparative Analysis of Biochemical Pathways

Identification and Characterization of Early Mission Phase Microorganisms Residing on the Mars Science Laboratory and Assessment of Their Potential to Survive Mars-like Conditions

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