From Lab to Cosmos: Three Frontiers in the Search for Signs of Life Beyond Earth - Sara Seager

Rethinking Habitability: Venus Clouds

• 💡 The search for life beyond Earth traditionally focuses on water as a solvent, but Venus's clouds, 50 km above the surface, offer temperatures suitable for life.
• ⚠️ Venusian clouds are made of concentrated sulfuric acid, which is highly destructive to Earth-based biomolecules like sugar (a proxy for DNA).
• ✅ Despite this, laboratory experiments show that some nucleic acid bases (ACGT), components of DNA, are stable in concentrated sulfuric acid for over a year.
• 🚀 A significant milestone is the stability of PNA (peptide nucleic acid), a DNA-related molecule, in concentrated sulfuric acid, suggesting complex molecules could exist.
• 🧠 The hypothesis proposes that concentrated sulfuric acid itself could serve as a solvent for life, expanding the concept of habitability.

Pioneering Venus Missions

• 🛰️ Existing Venus missions from ESA and NASA are not primarily focused on investigating the clouds for signs of life.
• 🌟 The "Morning Star missions" initiative aims for a series of private-public funded missions to Venus, starting with small, focused probes.
• 🔬 The Rocket Lab mission (target 2026) will use an auto-fluorescent nephilometer to detect organic particles (via fluorescence) and analyze cloud composition, challenging the assumption of pure sulfuric acid.
• 🧪 A future parachute mission concept involves deploying thousands of miniature molecular sensors (e.g., carbon nanotubes) to identify specific organic molecules in the Venusian atmosphere.
• 🎈 These sensor concepts are being tested through amateur weather balloon launches on Earth, demonstrating system functionality and data collection at high altitudes.

Unveiling Ionic Liquids

• serendipitously, laboratory experiments aimed at collecting Venus cloud particles led to the "rediscovery" of ionic liquids.
• 💧 Ionic liquids are salts that are liquid below 100°C and possess extremely low vapor pressure, meaning they do not evaporate easily unlike water.
• 🧬 These liquids are biomolecule friendly and could form naturally on planets where sulfuric acid interacts with nitrogen-containing organic compounds like amino acids.
• 🌌 This discovery suggests a new possibility for habitable exoplanets, particularly warm planets too hot or with too low pressure for liquid water, where small puddles of ionic liquids could sustain life.
• 🔭 The concept of ionic liquids as planetary solvents is a brand new frontier in astrobiology, potentially redefining what constitutes a habitable environment.