Callum Madeley.

The Origin of Life in Volcanic Hotsprings

A fascinating insight into the author's conjecture (hypothesis?) that life originated in fresh water hydrothermal fields on volcanic islands on early Earth. Provides an interesting commentary on words and their semantic baggage as a roadblock to defining "life", as well as exploring the need for environmantal variation such as chemical cycles and inputs of energy to initialise reactions. A stagnant pond will remain a stagnant pond if nothing in the environment changes! There exists an equally fascinating rebuttle, arguing Origin of Life studies as a whole are unconvincing, generating results in Toy Domains that cannot be scaled to any real world scenario. A great discussion on the progress (or lack thereof) made in Origin of Life research, and potential pathways forward, drawing parallels to the history of computing, solar astronomy, and artificial intelligence.

Emergence of a Habitable Planet

A guide to the first few hundred million years of Earth's history, describing how the hellish conditions of the Hadean Era transitioned into the world we know and love today. Places the Earth in its astrophysical context, discussing the interstellar environment, the faint young Sun, and the moon-forming impact.

Tracing the Inner Edge of the Habitable Zone

A really cool idea to use sulfur dioxide (SO2) as an indicator of dessicated, lifeless worlds. Since SO2 readily dissolves in water, its presence implies the absence of surface liquid water. However, SO2 can also be destroyed photochemically, so a caveat here is the planet's host star must have a relatively low ultraviolet (UV) flux, amenable to the persistence of detectable levels of SO2 in the upper atmosphere. This is the case for many M-dwarf stars, provided stellar flaring is infrequent.

Mantle Redox States and Volcanic Outgassing

A study exploring how the redox state of a planet's mantle influences the composition of volcanic outgassing, and therefore the atmospheric composition. This process allows us to link a planet's interior properties to its atmospheric characteristics, which is important for understanding planetary habitability and interpreting atmospheric observations of exoplanets.

The Origin of RNA Precursors on Exoplanets

High-energy ultraviolet (UV) radiation is damaging to life and can erode planetary atmospheres. However, UV light is also a key driver of prebiotic chemistry, facilitating the formation of life's building blocks. This paper explores the balance between these two effects, defining an 'abiogenesis zone' around stars where UV light is sufficiently energetic to initialise prebiotic chemistry without being overwhelmingly destructive. The authors examine the overlap between this abiogenesis zone and the traditional habitable zone, which is defined by the presence of liquid water on a planet's surface.