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Geological evidence for multiple climate transitions on Early Mars
Early Mars did not experience a single wet-to-dry transition, but seven such shifts in its palaeoclimatic history, as argued based on the planet’s stratigraphy, mineralogy and geomorphology.
- Edwin S. Kite
- & Susan Conway
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Article |
Isotopic constraints on lightning as a source of fixed nitrogen in Earth’s early biosphere
Spark discharge experiments suggest lightning was not the main source of bioavailable nitrogen for the established Archaean biosphere, but could have been significant for Earth’s earliest ecosystems.
- Patrick Barth
- , Eva E. Stüeken
- & Mark Claire
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Review Article |
Phosphorus availability on the early Earth and the impacts of life
A review of aqueous phosphorus availability on the Earth’s early surface suggests a range of phosphorus sources supplied the prebiotic Earth, but that phosphorus availability declined as life evolved and altered geochemical cycling.
- Craig R. Walton
- , Sophia Ewens
- & Matthew A. Pasek
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Article |
Mineral-catalysed formation of marine NO and N2O on the anoxic early Earth
Marine emissions of N2O could have sustained an early Archaean atmosphere of 0.8–6.0 ppb N2O without a protective ozone layer, according to mineral incubations combined with diffusion and photochemical modelling.
- Steffen Buessecker
- , Hiroshi Imanaka
- & Hinsby Cadillo-Quiroz
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Perspective |
Diverse geochemical conditions for prebiotic chemistry in shallow-sea alkaline hydrothermal vents
The spatial and temporal geochemical variability of alkaline hydrothermal systems in shallow waters could support prebiotic chemical reactions required for the emergence of life.
- Laura M. Barge
- & Roy E. Price
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Article |
A nitrogen-rich atmosphere on ancient Mars consistent with isotopic evolution models
The isotopic composition of nitrogen in the Martian atmosphere can be explained by a nitrogen-rich ancient atmosphere, according to models of atmospheric evolution.
- Renyu Hu
- & Trent B. Thomas
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Article |
A pole-to-equator ocean overturning circulation on Enceladus
Enceladus’s interior ocean could sustain a pole-to-equator overturning circulation, which might mean its bulk salinity is greater than that estimated from plume sampling by Cassini, according to numerical simulations.
- Ana H. Lobo
- , Andrew F. Thompson
- & Saikiran Tharimena
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Article |
Archaean seafloors shallowed with age due to radiogenic heating in the mantle
In contrast to present-day seafloor subsidence with age, there may have been Archaean seafloor shallowing and landmass exposure due to high internal heating in the mantle that halted subsidence, according to numerical models of mantle convection.
- Juan Carlos Rosas
- & Jun Korenaga
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Article |
Supply of phosphate to early Earth by photogeochemistry after meteoritic weathering
Reduced phosphorus species delivered by meteorites can be oxidized in reactions with hydrogen sulfide under ultraviolet light to provide a ready supply of phosphate to support prebiotic chemistry, as demonstrated by experiments.
- Dougal J. Ritson
- , Stephen J. Mojzsis
- & John. D. Sutherland
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Article |
Decline of giant impacts on Mars by 4.48 billion years ago and an early opportunity for habitability
The oldest known minerals from Mars have no strong shock features, indicating early cessation of giant impacts there, according to microanalysis of zircon and baddeleyite grains in meteorites.
- D. E. Moser
- , G. A. Arcuri
- & C. Davis
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Article |
Independent confirmation of a methane spike on Mars and a source region east of Gale Crater
A methane spike 15.5 ± 2.5 parts per billion by volume was detected in the Martian atmosphere above Gale Crater on 16 June 2013 by Mars Express, independently confirming the debated in situ observation by the Curiosity rover a day earlier.
- Marco Giuranna
- , Sébastien Viscardy
- & Marilena Amoroso
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Article |
O2 solubility in Martian near-surface environments and implications for aerobic life
Despite little O2 in the Martian atmosphere, concentrations of dissolved O2 in near-surface brines on Mars may be sufficient to support aerobic life, according to solubility calculations.
- Vlada Stamenković
- , Lewis M. Ward
- & Woodward W. Fischer
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Perspective |
The Martian subsurface as a potential window into the origin of life
Ancient hydrothermal deposits formed in the Martian subsurface may be the best targets for finding evidence for ancient life on Mars, and clues about the origin of life on Earth.
- Joseph R. Michalski
- , Tullis C. Onstott
- & Sarah Stewart Johnson
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Comment |
Exploring ocean worlds on Earth and beyond
The exploration of ocean worlds in the outer Solar System offers the opportunity to search for an independent origin of life, and also to advance our capabilities for exploring and understanding life in Earth’s oceans.
- Kevin Peter Hand
- & Christopher R. German
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Article |
Effects of primitive photosynthesis on Earth’s early climate system
Amplification of the methane cycle by anyoxygenic photosynthesis could have warmed early Earth and countered the faint young Sun, geochemical modelling suggests. A combination of H2-based and Fe2+-based photosynthesis acts to enhance methane fluxes.
- Kazumi Ozaki
- , Eiichi Tajika
- & Christopher T. Reinhard
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News & Views |
Atmosphere's solar shock
Frequent storms on the young Sun would have ejected energetic particles and compressed Earth's magnetosphere. Simulations suggest that the particles penetrated the atmosphere and initiated reactions that warmed the planet and fertilized life.
- Ramses Ramirez
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Perspective |
Connections between the bulk composition, geodynamics and habitability of Earth
Earth's composition differs from its meteoritic precursors. An evaluation of the evidence suggests that some material could have been lost to space during collisions, which may explain Earth's unusual plate tectonic regime and habitable climate.
- A. M. Jellinek
- & M. G. Jackson
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Letter |
Transient liquid water and water activity at Gale crater on Mars
Liquid water on equatorial Mars is inconsistent with large-scale climatic conditions. Humidity and temperature measurements by the Curiosity rover support the formation of subsurface liquid brines by hydration of perchlorates during the night.
- F. Javier Martín-Torres
- , María-Paz Zorzano
- & David Vaniman
Synthesis of 13C-depleted organic matter from CO in a reducing early Martian atmosphere