Everett Gibson - Academia.edu (original) (raw)
Papers by Everett Gibson
Proceedings of SPIE, Jul 11, 1997
In the initial report by McKay et al. on ALH84001 several lines of evidence were given to suggest... more In the initial report by McKay et al. on ALH84001 several lines of evidence were given to suggest the presence of biogenic activity on Mars: (i) the presence of the carbonate globules within fractures and pores of a 4.5 Gy old igneous rock after the primary crystallization event; (ii) formation age of the carbonates is younger than the age of the host igneous rock but older than the carbonate's age; (iii) SEM and TEM images of carbonate globules and assorted features resemble terrestrial biogenic structures and fossilized nanobacteria; (iv) the occurrence of magnetite and iron sulfide particles could have resulted from oxidation and reduction reactions known to be important in terrestrial microbial systems; and (v) presence ofPAHs associated carbonate globules indicating potential indigenous organic molecules. As noted in McKay et al., none of these observations is in itself conclusive proof for the existence of past life on Mars. Although there are alternative explanations for each ofthese phenomena taken individually, when they are considered collectively, particularly in view of their close spatial association, it was concluded that they may represent the first direct evidence for primitive life on early Mars. Since the initial report, additional supporting evidence and contradictory evidence, including alternative inorganic explanations have been presented. The time and temperatures of carbonate formation in ALH84001 continues to be hotly debated. Knott et al. suggests the carbonates were formed at 3.6 Gy, whereas Wadhwa and Lugmair noted the formation may be as late as 1.3 Gy. Turner et al. argue that the 3.6 Gy date is not well defined and additional studies are needed to define the carbonate formation date.
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The presence and abundance of lunar volatiles is an important consideration for ISRU (In Situ Res... more The presence and abundance of lunar volatiles is an important consideration for ISRU (In Situ Resource Utilisation) since this is likely to be a part of a strategy for supporting long term human exploration of the moon. The Lunar Volatile Resources Analysis Package (L-VRAP ...
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Title: The search for terrestrial nanobacteria as possible analogs for purported Martian nanofoss... more Title: The search for terrestrial nanobacteria as possible analogs for purported Martian nanofossils in the Martian meteorite ALH84001. Authors: Thomas-Keprta, Kathie L.; Wentworth, Susan J.; McKay, David S.; Stevens, Todd O.; Golden, DC; Allen, Carlton C.; Gibson, EK. ...
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Journal of Geophysical Research: Planets, 2000
Organic polymeric substances are a fundamental component of microbial biofilms. Microorganisms, e... more Organic polymeric substances are a fundamental component of microbial biofilms. Microorganisms, especially bacteria, secrete extracellular polymeric substances (EPS) to form slime layers in which they reproduce. In the sedimentary environment, biofilms commonly ...
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Selected Martian meteorites contain reduced carbon phases associated with clay minerals. The sour... more Selected Martian meteorites contain reduced carbon phases associated with clay minerals. The sources of the reduced carbon within the meteorites appears to be associated with fluids which have caused preterrestrial alteration of primary silicates.
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Following the Apollo era the moon was considered a volatile poor body. Samples collected from the... more Following the Apollo era the moon was considered a volatile poor body. Samples collected from the Apollo missions contained only ppm levels of water formed by the interaction of the solar wind with the lunar regolith [1]. However more recent orbiter observations have indicated that water may exist as water ice in cold polar regions buried within craters at concentrations of a few wt. % [2]. Infrared images from M3 on Chandrayaan-1 have been interpreted as showing the presence of hydrated surface minerals with the ongoing hydroxyl/water process feeding cold polar traps. This has been supported by observation of ephemeral features termed "space dew" [3]. Meanwhile laboratory studies indicate that water could be present in appreciable quantities in lunar rocks [4] and could also have a cometary source [5]. The presence of sufficient quantities of volatiles could provide a resource which would simplify logistics for long term lunar missions. The European Space Agency (ESA'...
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Sets of Antarctic Dry Valley sediment samples were analyzed by geochemical analysis methods. Simi... more Sets of Antarctic Dry Valley sediment samples were analyzed by geochemical analysis methods. Similarities in chemical properties to Mars soils were found.
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Science, 1969
Carrier-gas fusion extractions of total nitrogen in 22 chondritic meteorites indicate a wide vari... more Carrier-gas fusion extractions of total nitrogen in 22 chondritic meteorites indicate a wide variation in total nitrogen contents, ranging from 660 parts per million for an enstatite chondrite to 18 parts per million for an ordinary chondrite. Total nitrogen and total carbon contents of individual chondrites do not show a positive correlation.
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Journal of Geophysical Research, 1983
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Geochimica et Cosmochimica Acta, 1971
Total nitrogen and carbon abundances in twenty-seven samples of nineteen carbonaceous chondrites ... more Total nitrogen and carbon abundances in twenty-seven samples of nineteen carbonaceous chondrites have been measured. The results obtained indicate that the meteorites enriched in nitrogen are similarly enriched in carbon. The results support the ...
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Geochimica et Cosmochimica Acta, 1971
Total nitrogen and carbon abundances in twenty-seven samples of nineteen carbonaceous chondrites ... more Total nitrogen and carbon abundances in twenty-seven samples of nineteen carbonaceous chondrites have been measured. The results obtained indicate that the meteorites enriched in nitrogen are similarly enriched in carbon. The results support the ...
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VOLATILE DETERMINATIONS OF INDIVIDUAL FLUID INCLUSIONS WITHIN THE 3.4 BY NORTH POLE BARITES FROM ... more VOLATILE DETERMINATIONS OF INDIVIDUAL FLUID INCLUSIONS WITHIN THE 3.4 BY NORTH POLE BARITES FROM THE WARRAWOONA GROUP, NORTHWESTERN AUSTRALIA; NA Sommer 11, LEMSCO/JSC, 2400 NASA Rd. ...
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Thermochimica Acta
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Lunar and Planetary Science Conference, Mar 1, 1999
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Lunar and Planetary Science Conference, Mar 1, 1985
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Anal Chem, 1980
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Proceedings of SPIE, Jul 11, 1997
In the initial report by McKay et al. on ALH84001 several lines of evidence were given to suggest... more In the initial report by McKay et al. on ALH84001 several lines of evidence were given to suggest the presence of biogenic activity on Mars: (i) the presence of the carbonate globules within fractures and pores of a 4.5 Gy old igneous rock after the primary crystallization event; (ii) formation age of the carbonates is younger than the age of the host igneous rock but older than the carbonate's age; (iii) SEM and TEM images of carbonate globules and assorted features resemble terrestrial biogenic structures and fossilized nanobacteria; (iv) the occurrence of magnetite and iron sulfide particles could have resulted from oxidation and reduction reactions known to be important in terrestrial microbial systems; and (v) presence ofPAHs associated carbonate globules indicating potential indigenous organic molecules. As noted in McKay et al., none of these observations is in itself conclusive proof for the existence of past life on Mars. Although there are alternative explanations for each ofthese phenomena taken individually, when they are considered collectively, particularly in view of their close spatial association, it was concluded that they may represent the first direct evidence for primitive life on early Mars. Since the initial report, additional supporting evidence and contradictory evidence, including alternative inorganic explanations have been presented. The time and temperatures of carbonate formation in ALH84001 continues to be hotly debated. Knott et al. suggests the carbonates were formed at 3.6 Gy, whereas Wadhwa and Lugmair noted the formation may be as late as 1.3 Gy. Turner et al. argue that the 3.6 Gy date is not well defined and additional studies are needed to define the carbonate formation date.
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The presence and abundance of lunar volatiles is an important consideration for ISRU (In Situ Res... more The presence and abundance of lunar volatiles is an important consideration for ISRU (In Situ Resource Utilisation) since this is likely to be a part of a strategy for supporting long term human exploration of the moon. The Lunar Volatile Resources Analysis Package (L-VRAP ...
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Title: The search for terrestrial nanobacteria as possible analogs for purported Martian nanofoss... more Title: The search for terrestrial nanobacteria as possible analogs for purported Martian nanofossils in the Martian meteorite ALH84001. Authors: Thomas-Keprta, Kathie L.; Wentworth, Susan J.; McKay, David S.; Stevens, Todd O.; Golden, DC; Allen, Carlton C.; Gibson, EK. ...
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Journal of Geophysical Research: Planets, 2000
Organic polymeric substances are a fundamental component of microbial biofilms. Microorganisms, e... more Organic polymeric substances are a fundamental component of microbial biofilms. Microorganisms, especially bacteria, secrete extracellular polymeric substances (EPS) to form slime layers in which they reproduce. In the sedimentary environment, biofilms commonly ...
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Selected Martian meteorites contain reduced carbon phases associated with clay minerals. The sour... more Selected Martian meteorites contain reduced carbon phases associated with clay minerals. The sources of the reduced carbon within the meteorites appears to be associated with fluids which have caused preterrestrial alteration of primary silicates.
Bookmarks Related papers MentionsView impact
Following the Apollo era the moon was considered a volatile poor body. Samples collected from the... more Following the Apollo era the moon was considered a volatile poor body. Samples collected from the Apollo missions contained only ppm levels of water formed by the interaction of the solar wind with the lunar regolith [1]. However more recent orbiter observations have indicated that water may exist as water ice in cold polar regions buried within craters at concentrations of a few wt. % [2]. Infrared images from M3 on Chandrayaan-1 have been interpreted as showing the presence of hydrated surface minerals with the ongoing hydroxyl/water process feeding cold polar traps. This has been supported by observation of ephemeral features termed "space dew" [3]. Meanwhile laboratory studies indicate that water could be present in appreciable quantities in lunar rocks [4] and could also have a cometary source [5]. The presence of sufficient quantities of volatiles could provide a resource which would simplify logistics for long term lunar missions. The European Space Agency (ESA'...
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Sets of Antarctic Dry Valley sediment samples were analyzed by geochemical analysis methods. Simi... more Sets of Antarctic Dry Valley sediment samples were analyzed by geochemical analysis methods. Similarities in chemical properties to Mars soils were found.
Bookmarks Related papers MentionsView impact
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Science, 1969
Carrier-gas fusion extractions of total nitrogen in 22 chondritic meteorites indicate a wide vari... more Carrier-gas fusion extractions of total nitrogen in 22 chondritic meteorites indicate a wide variation in total nitrogen contents, ranging from 660 parts per million for an enstatite chondrite to 18 parts per million for an ordinary chondrite. Total nitrogen and total carbon contents of individual chondrites do not show a positive correlation.
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Journal of Geophysical Research, 1983
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Geochimica et Cosmochimica Acta, 1971
Total nitrogen and carbon abundances in twenty-seven samples of nineteen carbonaceous chondrites ... more Total nitrogen and carbon abundances in twenty-seven samples of nineteen carbonaceous chondrites have been measured. The results obtained indicate that the meteorites enriched in nitrogen are similarly enriched in carbon. The results support the ...
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Geochimica et Cosmochimica Acta, 1971
Total nitrogen and carbon abundances in twenty-seven samples of nineteen carbonaceous chondrites ... more Total nitrogen and carbon abundances in twenty-seven samples of nineteen carbonaceous chondrites have been measured. The results obtained indicate that the meteorites enriched in nitrogen are similarly enriched in carbon. The results support the ...
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VOLATILE DETERMINATIONS OF INDIVIDUAL FLUID INCLUSIONS WITHIN THE 3.4 BY NORTH POLE BARITES FROM ... more VOLATILE DETERMINATIONS OF INDIVIDUAL FLUID INCLUSIONS WITHIN THE 3.4 BY NORTH POLE BARITES FROM THE WARRAWOONA GROUP, NORTHWESTERN AUSTRALIA; NA Sommer 11, LEMSCO/JSC, 2400 NASA Rd. ...
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Thermochimica Acta
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Lunar and Planetary Science Conference, Mar 1, 1999
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Lunar and Planetary Science Conference, Mar 1, 1985
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Anal Chem, 1980
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