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icyMARS Report Summary

Project ID: 307496
Funded under: FP7-IDEAS-ERC
Country: Spain

Mid-Term Report Summary - ICYMARS (Cold and wet early Mars: Proposing and testing a new theory to understand the early Martian environments)

The “icyMARS” project aims for a paradigmatic shift towards the understanding of the evolution of early Mars, defining and testing a new hypothesis: that the Martian environment was characterized by global mean freezing conditions, as predicted by climate models, and at the same time a vigorous hydrogeological cycle was active during hundreds of millions of years, as confirmed by geomorphological and mineralogical analyses: a “cold and wet” early Mars. For this purpose, “icyMARS” follows an ambitious interdisciplinary approach, working on four interconnected Themes: (1) the geomorphological characterization of ancient glacial and periglacial features; (2) geochemical studies on Martian aqueous mineralogy at subzero temperatures; (3) the understanding of the link between the global climate change on early Mars and the mineral transition from hydrated silicate- to sulfate-dominated sediments; and (4) the habitability of cold aqueous solutions, brines and hygroscopic salts on Mars.

We are currently involved in several innovative investigations, some of which have already led to the publication of groundbreaking advances (not just incremental science) in each Theme:
(1) The first part of the accomplished and published work done by the “icyMARS” Team concerns the geomorphological characterization of a cold early Mars. In the light of the recent advances by landed missions, the obvious site choice for our work was Gale crater, the most carefully analyzed place on Mars to date. By effectively characterizing the geomorphology of Gale using a combination of large-scale (orbital) to detailed (rover) datasets, we demonstrated that Gale’s geomorphological record preserves the clues to understand the environmental transitions on a “cold and wet” early Mars. Our Team pioneered the consideration of Gale as an ancient glacial and periglacial landscape.
We have extended our geomorphological investigations about water/ice interactions on the Martian landscape, and have published our results on the following items: (i) we discovered evidence for tsunami activity reshaping the ice-covered Hesperian littoral landforms, (ii) analyzed periglacial landforms in Argyre, (iii) tied the origin and evolution of the circum-Chryse outflow channels to freeze-thaw processes during and after the Hesperian, and (iv) presented evidence for an episode of extensive polar plateau retreat in the South Polar layered deposits during the Late Amazonian. We are currently finishing our work on the identification of features indicative of glaciers calving and iceberg rafting in lakes (and seas?) in Hellas and the lowlands.
(2) In Theme 2, “icyMARS” focused on the process of melting/freezing of ionic solutions or brines at and below 273K, and the role of the enthalpy of phase transition in this process. Innovative published outcomes include the analysis of multiple eutectic and/or peritectic points in binary and multicomponent systems of enantiotropic substances (i.e., the different phases of Mg-sulfate), and descriptions of the enhanced overfreezing effect due to the continuous increasing of the ionic strength in systems undergoing evaporation.
We also investigated long-term oxidation processes taking place in anoxic environments, as those occurred during the weathering of primary minerals in early Mars. Our results suggest that pyrite dissolution can act as a natural Fenton reagent, influencing the oxidation of third-party species during the long–term evolution of geochemical systems, even in the early Mars oxygen-limited environments.
In addition, we have developed and published models to describe the paths of Li isotopic fractionation on Mars, as Li isotopic ratios can inform about weathering conditions on Mars in the past, including the extent of basalt weathering, supersaturation and evaporation rates of initial solutions, and ambient temperature. This is very timely because NASA’s Mars2020 rover will be capable of performing in situ measurements of Li isotopes on Martian alteration products, and there are ongoing [Li] measurements by MSL/Curiosity.
(3) Theme 3 has resulted in two major achievements in Mars mineralogy. Our aim was to understand the sedimentary mineralogy on Mars, where mineral sequences show that salts generally do not appear together with clays. First, “icyMARS” tackled this problem by assuming that the driving factor separating the different mineralogies was temperature (climate change). To our surprise, we have discovered that the synthesis of clays vs sulfates on Mars was initially controlled by the reactive surface of primary minerals. This was totally unexpected and is one of the major outcomes of “icyMARS”.
And second, we have kinetically modeled the stability boundaries for the synthesis of sulfates and phyllosilicates. Also unexpectedly, under some conditions our results are consistent with a contemporary formation of all major water-derived mineralogies in different aqueous environments during the wet Noachian/Hesperian times, revealing an active and heterogeneous early Mars.
Theme 3 has come far, and the results are actually beyond expectations.
(4) The fourth Theme relates to the understanding of the nature of cold aqueous solutions and salt deposits on early Mars, which is key to determine the possibilities for the origin of life, and to assess past and current scenarios of habitability. To gain meaningful progress on Theme 4, it was first necessary to have substantial advances in the previous Themes, particularly #2 and #3, which would set the experimental conditions to be applied on Theme 4. We developed several new concepts related to the potential of low-temperature solutions and brines that existed on early Mars to support growth and/or survivability of Martian analogue extremophiles, with the aim of fingerprinting putative paths of microbial adaptation on a “cold and wet” early Mars.
In addition, we published the innovative proposal of considering the Argyre basin as a candidate site for in situ astrobiological reconnaissance. We discussed in detail the astrobiological significance of some landscape features and terrain types in the Argyre region that are promising and accessible sites for astrobiological exploration, particularly those associated with the migration of water/ice/brines along Argyre’s structures and the venting of volatiles.

In perspective:
Research from “icyMARS” has already produced innovative results in different fields (geomorphology, geochemistry, mineralogy, astrobiology), leading to a large number of peer-reviewed publications, meeting communications and press releases. Importantly, our pioneering concept of a “cold and wet” early Mars has been already embraced by several other research groups dealing with the conundrum of the early Mars environment. As a consequence, our new “cold and wet” paradigm for early Mars is now widely acknowledged and is being further developed by the community. The Team is organizing two parallel sessions at the 2016 AGU Meeting in San Francisco, devoted to put the “cold and wet early Mars” hypothesis in context of other decades-long studies about the early Mars environment: There will be over 40 presenters, and we expect lively discussions: stay tuned to “icyMARS”!

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