Sara Seager: Exoplanet Atmospheres and the Search for Life Beyond Earth

The Quest for Extraterrestrial Life

• 💡 The core objective in searching for life on exoplanets is to identify gases that don't belong in their atmospheres, much like oxygen indicates life on Earth.
• 🔭 Thousands of exoplanets have been discovered, with many being "transiting exoplanets" that periodically pass in front of their host stars.
• 🔬 Transmission spectroscopy is the primary method used to detect and characterize exoplanet atmospheres by observing changes in starlight brightness at different wavelengths.

Current Capabilities and Challenges

• ✨ The James Webb Space Telescope has successfully used transmission spectroscopy to detect atmospheric gases, such as carbon dioxide, on hot, giant exoplanets.
• ⚠️ Observing Earth-sized planets is currently challenging due to their small size; research primarily focuses on "Earth cousins" around smaller stars.
• ⚡ Red dwarf stars, like those in the Trappist-1 system, present significant hurdles due to frequent stellar flares and star spots that contaminate atmospheric signals.

The Venus Phosphine Controversy

• 💬 The controversial discovery of phosphine on Venus highlighted the difficulties in confirming biosignatures, facing challenges with noisy data, gas identification, and ruling out non-biological sources.
• 🧪 Despite Venus's sulfuric acid clouds, new research suggests that sulfuric acid could potentially serve as a solvent for life, with amino acids and organic chemistry showing stability within it.
• 🚀 The Morning Star missions are planned private-public partnerships aiming to send probes and balloons to Venus to investigate its atmosphere for complex organic molecules.

Future Directions in Astrobiology

• 🧠 Future efforts include developing detailed atmospheric models and utilizing advanced telescopes like the Habitable Worlds Observatory to find true Earth twins.
• 📡 The search also encompasses techno-signatures (e.g., industrial pollutants like CFCs) and ambitious concepts such as the solar gravitational lens telescope for high-resolution imaging.
• 🌌 Current atmospheric characterization is limited to a range of hundreds of light-years, with interstellar probes like Starshot representing a multi-decade endeavor.