Related papers: Early Mars' habitability and global cooling by H2-…

Hydrogen in rocky planet atmospheres has been invoked in arguments for extending the habitable zone via N2-H2 and CO2-H2 greenhouse warming, and providing atmospheric conditions suitable for efficient production of prebiotic molecules. On…

The low temperatures and high ultraviolet (UV) radiation levels at the surface of Mars today currently preclude the survival of life anywhere except perhaps in limited subsurface niches. Several ideas for making the martian surface more…

For decades, scientists have tried to explain the evidence for fluvial activity on early Mars, but a consensus has yet to emerge regarding the mechanism for producing it. One hypothesis suggests early Mars was warmed by a thick greenhouse…

Motility is a ubiquitous feature of microbial life on Earth, and is widely regarded as a promising biosignature candidate. In the search for motile organisms, it is therefore valuable to have rough estimates for the number of such microbes…

Mars today has no active volcanism and its atmosphere is oxidizing, dominated by the photochemistry of CO2 and H2O. Using a one-dimensional photochemical model, we consider whether plausible volcanic gas fluxes could have switched the…

The climate of early Mars has been hotly debated for decades. Although most investigators believe that the geology indicates the presence of surface water, disagreement has persisted regarding how warm and wet the surface must have been and…

The Curiosity rover recently detected a background of 0.7 ppb and spikes of 7 ppb of methane on Mars. This in situ measurement reorients our understanding of the Martian environment and its potential for life, as the current theories do not…

CO2+H2 greenhouse warming has recently emerged as a promising scenario to sufficiently warm the early martian surface to allow the formation of valley networks and lakes. Here we present numerical 3-D global climate simulations of the early…

Latest research in planet formation indicate that Mars formed within a few million years (Myr) and remained a planetary embryo that never grew to a more massive planet. It can also be expected from dynamical models, that most of Mars'…

Abundant geomorphological and geochemical evidence of liquid water on the surface of early Mars during the late Noachian and early Hesperian periods needs to be reconciled with a fainter young Sun. While a dense CO2 atmosphere and related…

The present Martian climate is characterized by a cold and dry environment with a thin atmosphere of carbon dioxides (CO2). In such conditions, the planetary climate and habitability are determined by the distribution of CO2 between…

The deuterium-to-hydrogen (D/H or 2H/1H) ratio of Martian atmospheric water (~6x standard mean ocean water, SMOW) is higher than that of known sources, requiring planetary enrichment. A recent measurement by NASA's Mars Science Laboratory…

Mars finished forming while the solar nebula was still present, and acquired its primordial atmosphere from this reservoir. The absence of a detectable cometary xenon signature in the present-day Martian atmosphere suggests that the capture…

In a previous paper (Chassefi\`ere et al., Icarus 223, 878-891, 2013), we have shown that most volcanic sulfur released to early Mars atmosphere could have been trapped in the cryosphere under the form of CO2-SO2 clathrates. Huge amounts of…

Recent observations have evidenced traces of methane CH4 heterogeneously distributed in the martian atmosphere. However, because the lifetime of CH4 in the atmosphere of Mars is estimated to be around 300-600 years on the basis of…

We compare estimates of atmospheric precipitation during the Martian Noachian-Hesperian boundary 3.8 Gyr ago as calculated in a radiative-convective column model of the atmosphere with runoff values estimated from a geomorphological…

The climate of Mars likely evolved from a warmer, wetter early state to the cold, arid current state. However, no solutions for this evolution have previously been found to satisfy the observed geological features and isotopic measurements…

Planet Mars past environmental conditions were similar to the early Earth, but nowadays they are similar to those of a very cold desert, irradiated by intense solar UV light. However, some terrestrial lifeform showed the capability to adapt…

Early Mars had rivers, but the cause of Mars' wet-to-dry transition remains unknown. Past climate on Mars can be probed using the spatial distribution of climate-sensitive landforms. We analyzed global databases of water-worked landforms…

We review the abundance and diversity of terrestrial rock hosted life, the environments it inhabits, the evolution of its metabolisms, and its fossil biomarkers to provide guidance in the search for the biomarkers of rock hosted life on…