Martian gullies and their Earth analogues: introduction

Abstract

Martian gullies are widespread landforms in the mid-latitudes of Mars. When the first reports of these kilometre-scale features were published in 2000, they were controversially hailed as a sign of recent flows of liquid water on the surface of Mars. This supposition was contrary to our understanding of recent environmental conditions on Mars, under which water should not exist in its liquid form. In response to their discovery, researchers proposed a wide range of scenarios to explain this apparent paradox, including scenarios driven by CO 2 , climate change or the presence of a liquid water aquifer. This Special Publication is a collection of papers arising from the topics discussed at the Second International Workshop on Martian Gullies held at the Geological Society, London. A review paper opens the Special Publication and thereafter the papers are presented under three themes: Martian remote sensing, Earth analogues and laboratory simulations. This Special Publication establishes the state of the art in Martian gully research, presents the latest observations and interpretations of the present-day activity and long-term evolution of Martian gullies, explores the role of Earth analogues, highlights novel experimental work and identifies future avenues of research. The importance of gullies as a potential marker of habitable environments on Mars underlines their importance in framing space exploration programmes. Gold Open Access: This article is published under the terms of the CC-BY 4.0 license.

Reflectance study of ice and Mars soil simulant associations – I. H2O ice

“…Various morphological features provide evidence of recent redistribution of water ice to mid-latitudes. These include near-surface ground ice (Mustard et al, 2001), gullies (Conway et al, 2019), polygons and other patterned ground (Mangold et al, 2004), viscous flow features , and rocky glaciers (Head et al, 2003). Water ice in the close subsurface below a thin desiccated layer of dust is found at latitudes poleward of 60 • in both hemispheres with a concentration often exceeding 50 wt% (Feldman et al, 2008).…”

Landscape domains and information surfaces: Data collection, recording and citation using decimal latitude‐longitude geolocation via the FAIR principles

“…ML and related techniques (Arabameri et al, 2020;Li et al, 2019) might be used to identify and provide inventory data on gullies, as has also been employed for rock glaciers (Erharter et al, 2022). The importance of communication between scientists investigating terrestrial and Martian features is evident in the recent volume about Martian gully systems (Conway et al, 2019) although the terrestrial examples do not have geo-referencing.…”

“…To establish earth surface ecosystems, it is necessary to establish reference systems which encompass topography and onto which information can be mapped to establish 'geomorphic information fields' (or surfaces) within the CZ. Sharing geomorphic information is also required to link earth surface features elsewhere, for example to those on Mars (Balme et al, 2011;Conway et al, 2019). No attempt is made to provide a comprehensive discussion, rather the examples and references provided are indicative of how dLL specifications can and might be used widely and to incorporate the FAIR data principles of findability, accessibility, interoperability and reusability.…”

The Timing of Alluvial Fan Formation on Mars

“…Kite 2019). Since the end of the era of regionally-integrated valley networks in the early Hesperian ∼ 3.4 Ga (Fassett & Head 2008), fluvial activity on Mars primarily produced shorter landforms (Goudge et al 2016), including small, 'pollywog', exit breach craters (Wilson et al 2016;Warren et al 2021), alluvial fans (Moore & Howard 2005;Kraal et al 2008;Grant & Wilson 2011;Hauber et al 2013;Kite et al 2017;Grant & Wilson 2019;Wilson et al 2021), and gullies (which may or may not be fluvial in origin; see Conway et al (2019)). Some of the alluvial fans are associated with aqueous minerals (hydrated silica; e.g.…”