About

Welcome to the the SPACE Program! SPACE: a Sub-neptune Planetary Atmosphere Characterization Experiment, is a Hubble Space Telescope Large Treasury Program (GO 17192) that will characterize the atmospheres and host stars of eight sub-Neptune exoplanets.

Sub-Neptunes, with radii between 2 and 3.5x that of the Earth, are one of the most common types of exoplanets, and yet there are still major open questions about how they form and evolve. This program will systematically study sub-Neptunes across a grid of planet radius and temperature, specifically designed to reveal how their atmospheres are shaped by UV photochemistry, equilibrium cloud formation, atmospheric metal enrichment, vertical mixing, and photoevaporation.

The program is part of the broader HST-TESS Exoplanet Initiative, which was recommended by STScI to capitalize on the wealth of sub-Neptunes discovered by the Transiting Exoplanet Survey Satellite.