The first Interra papers.

Interra is an open project that models how planets change over billions of years, linking their interiors, atmospheres, and the gases that escape to space. This paper introduces the project and explains how we test the models against real observations of planets in and beyond the Solar System.

We introduce the Interra Project, an open framework for simulating the coupled evolution of planetary interiors, atmospheres, outgassing, and escape over geological time. We describe the modelling approach, the production and validation of model ensembles, and how those ensembles are compared against planetary and exoplanetary observations through telescope simulators. Provisional abstract for the 2027 release.

Young planets are born partly molten. We work out how long that internal magma ocean can last, in some cases for billions of years, and what keeps it molten, because a still-molten interior leaves a lasting mark on a planet’s atmosphere.

We quantify how long magma oceans persist within rocky and volatile-rich planets across the Interra ensembles, identifying the compositional, thermal, and orbital conditions that prolong or shorten the molten phase, and the consequences for the observable atmosphere. Provisional abstract for the 2027 release.

As a planet forms, some of its volatile elements get trapped in the iron core, hidden from the surface for good. We quantify how much is locked away and how this hidden reservoir changes the atmosphere a planet can build over time.

We quantify how core-mantle equilibration during accretion partitions volatile elements into a planet’s metallic core, depleting the budget available to the mantle and atmosphere. Across the Interra ensembles we assess how this hidden reservoir reshapes long-term outgassing and observable composition. Provisional abstract for the 2027 release.

Whether a planet’s chemistry is oxidising or reducing shapes everything from its gases to its potential for life, and it shifts as the planet ages. We follow this redox evolution for super-Earths and sub-Neptunes from birth onward.

We trace how the oxidation state of super-Earth and sub-Neptune interiors and atmospheres evolves over time across the Interra ensembles, linking accretional starting conditions to the redox trajectories that govern atmospheric chemistry and observability. Provisional abstract for the 2027 release.

The gases in a planet’s atmosphere are constantly reacting: sometimes they settle into balance, sometimes they are held out of it by sunlight, mixing, and volcanism. We model both cases and find which leave a visible mark in a planet’s light.

We model the atmospheric chemistry of the Interra ensembles in both thermochemical equilibrium and disequilibrium, driven by mixing, photochemistry, and outgassing, and identify where departures from equilibrium imprint detectable spectral signatures. Provisional abstract for the 2027 release.

Planets can lose their atmospheres to space, and how much they lose helps decide whether they end up hot, temperate, or barren. We map these climate outcomes and what tips a planet from one into another.

We couple atmospheric escape to climate across the Interra ensembles, mapping how the loss of volatiles to space sets the boundaries between distinct long-term climate regimes for rocky and volatile-rich planets. Provisional abstract for the 2027 release.

Close-in planets are continually flexed by their star’s gravity, and this tidal heating can keep their interiors molten and slowly reshape their orbits. We model how this dynamical push couples to a planet’s interior and atmosphere over time.

We model the tidal heating and orbital evolution of close-in rocky planets and sub-Neptunes across the Interra ensembles, quantifying how dynamical forcing couples to interior and atmospheric evolution, prolonging molten interiors and reshaping long-term climate. Provisional abstract for the 2027 release.

We turn thousands of simulated planets into the kind of data telescopes actually collect, then ask what patterns emerge across the whole population, so observers know what to expect and how to read it.

We generate synthetic observables, transmission and emission spectra, bulk densities, and population-level statistics, for the full Interra ensembles, processed through instrument pipelines, to forecast how evolutionary diversity manifests across the rocky exoplanet population. Provisional abstract for the 2027 release.

We zoom in on the handful of real planets JWST can study best and predict what their atmospheres might look like, giving observers a concrete guide for what to look for and what it would mean.

We produce tailored synthetic observables for the specific super-Earths and sub-Neptunes most accessible to JWST, mapping Interra’s evolutionary predictions onto named targets to guide observing strategy and interpretation. Provisional abstract for the 2027 release.