On the importance of laboratory experiments for interpreting exoplanet observations

TL;DR

Laboratory experiments are essential for interpreting exoplanet observations by providing critical data on atmospheres, interiors, surface compositions, and potential biosignatures, thereby enhancing models and understanding of diverse exoplanet worlds.

Contribution

This paper reviews key laboratory experimental techniques and their role in improving models of exoplanet atmospheres, interiors, and surface compositions, especially for low-mass planets.

Findings

Laboratory data on outgassing and volatile solubilities link exoplanet interiors to atmospheres.

Experimental methods constrain spectroscopic properties of atmospheric gases and aerosols.

Surface and astrobiology experiments inform on biosignatures and habitability.

Abstract

With the advanced capabilities of ground- and space-based telescopes, exoplanet science is beginning to characterize the physics and chemistry of exoplanet atmospheres. However, interpreting exoplanet observations requires sophisticated modeling tools that rely on laboratory data to provide critical inputs and constraints. In preparation for the influx of observational data that the coming decades will bring, laboratory experiments that simulate the diverse conditions expected in exoplanet atmospheres, surfaces and interiors are vital to advancing models and thereby our understanding of these worlds. Here we discuss the key areas where laboratory experiments are providing fundamental data for exoplanet models, particularly for low-mass planets from rocky worlds to sub-Neptunes. First, we present a series of experiments to measure outgassing and volatile solubilities that are essential for establishing the connection between low-mass exoplanet interiors and their observable atmospheres. We then discuss additional laboratory techniques that can be used to understand the interior-atmosphere connection and simulate the high pressure-high temperature conditions of exoplanet interiors. Next, we summarize the experimental methods used to constrain the spectroscopic properties of atmospheric gases and aerosols along with their formation and reaction mechanisms. We also discuss how similar methods can be used to constrain exoplanet surface compositions, which is important for interpreting observations of atmosphere-less worlds. Finally, we conclude by presenting several examples of astrobiology experiments that constrain how life can modify the atmosphere and surface of rocky exoplanets. Together, these laboratory efforts are crucial to maximizing the scientific yield of exoplanet observations in the coming decades.