Planet formation and evolution pathways can change the bulk composition, properties, and early evolution of the forming planets. In Module 2, our team explores the interplay and co-evolution of forming giant and rocky planets and the protoplanetary disk. We explore how do large gaps and the transport of pebbles through the planet-forming disks impacts the composition of the forming planets. We also use simulations to identify population-level trends between the details of planet formation and the compositions of planets.

Not all young habitable planets remain hospitable to life: Multiple processes can doom or destroy Earth-like planets.  In our Module 3 we explore known threats to habitable planetary systems and apply the lessons learned to nearby planetary systems to help identify the most promising targets for habitable planet searchers. Threats include the orbital dynamical instability of planetary systems and atmospheric loss processes.

In addition to advancing knowledge, the Alien Earths team's research was defined to best inform current and future NASA exoplanet missions. With multiple missions concepts proposed and under development that aim to find and characterize habitable planets and search these for signatures of life, having the right, comprehensive information on the target planets is essential. Knowing which nearby systems to target, which planets to focus at, how to interpret incomplete information on the planets studied is essential for the success of these missions. Effective target selection can potentially save hundreds of millions of dollars and lower missions risks. Therefore, in our fourth module, our Alien Earths team applies the integrated knowledge from our entire project to nearby planetary systems – the potential targets for biosignature surveys – and uses survey simulations to quantify this information can best guide NASA missions.