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

For thousands of years, inspired by the starry night sky, humanity has wondered what lies beyond Earth. In the past three decades, that question has transformed from philosophy to data: astronomers have discovered thousands of exoplanets orbiting stars other than the Sun, revealing that small rocky worlds are common in our galaxy. The exoplanet census has made one thing clear: Earth-like conditions may not be the norm. If most observationally accessible rocky worlds are hotter and more chemically aggressive than Earth, then limiting habitability to water-rich environments may be too restrictive. We therefore turned to the laboratory to test whether key biomolecules can survive in non-water solvents. Our recent experiments show that some key biomolecules—including amino acids, peptides, and a nucleic-acid–like polymer—can remain stable in concentrated sulfuric acid, the dominant liquid in Venus’ temperate cloud layer. Under the same conditions, lipids can even self-assemble into vesicles. This surprising chemistry reopens the question of whether Venus might be habitable in the form of an aerial biosphere. While building instrumentation and conducting laboratory studies for Venus’ clouds, we inadvertently “rediscovered” ionic liquids—exotic, polar, non-volatile solvents—and showed for the first time that hydrogen sulfate ionic liquids can form naturally from planetary materials. Due in part to their extremely low vapor pressure, ionic liquids remain stable under extreme conditions where water cannot exist. By considering water-alternative solvents, we can chart new frontiers that integrate quantum chemistry, biomolecular chemistry, planetary physics, and space exploration—potentially transforming our understanding of life’s origins and its possibilities across the cosmos.

Bio: Professor Sara Seager is a Professor of Physics, Planetary Science, and Aeronautics and Astronautics at the Massachusetts Institute of Technology, where she holds the Class of 1941 Professor Chair. Her research ranges from the foundations of exoplanet atmospheres to innovative theories about life on other worlds and the development of novel space mission concepts. She was Deputy Science Director of NASA’s TESS mission, Principal Investigator of the JPL–MIT CubeSat ASTERIA, and has led major efforts to design space-based direct imaging missions with Starshade to discover another Earth. She now leads the Morning Star Missions to Venus in search of signs of life in Venus’ clouds. Her many honors include a MacArthur “genius” award, the Kavli Prize in Astrophysics, membership in the National Academy of Sciences, appointment as an Officer of the Order of Canada, and having Asteroid 9729 Seager named in her honor. She is the author of The Smallest Lights in the Universe: A Memoir. In Fall 2026, Professor Seager will move to Canada as the North Star Distinguished Professor at the University of Toronto’s Canadian Institute for Theoretical Astrophysics.