Scientists at the Massachusetts Institute of Technology (MIT) have identified ionic liquids as a potential medium for life in environments previously considered inhospitable, challenging the long-held notion that liquid water is the sole prerequisite for life.
The research, led by Professor Sara Seager and postdoctoral researcher Rachana Agrawal, demonstrated that a combination of sulfuric acid and glycine, a common amino acid, can naturally form a stable ionic liquid. These fluids exhibit remarkable stability, remaining liquid at temperatures as high as 180°C and under significantly lower pressures than Earth's atmosphere. Unlike water, ionic liquids have minimal evaporation, allowing them to persist in extreme conditions. This stability is due to their nature as salts that remain liquid at relatively low temperatures, often below 100°C.
The implications of this discovery are far-reaching, with Agrawal suggesting that the inclusion of ionic liquids could dramatically expand the habitable zones for all rocky planets. This opens up a vast array of celestial bodies, previously overlooked due to the absence of liquid water, as potential candidates for harboring life. Professor Seager described the discovery as opening a "Pandora's box" of new research avenues.
The formation of these ionic liquids is plausible on other planets, as sulfuric acid can be generated through volcanic activity, and nitrogen-containing organic compounds are abundant throughout the solar system, often delivered by asteroids. The MIT researchers demonstrated that these reactions can occur on basalt rock surfaces, which are common on many rocky planets, further solidifying the potential for naturally occurring ionic liquids in extraterrestrial settings.
This research moves beyond an Earth-centric view of life. While water is essential for life as we know it, the fundamental requirement for habitability may simply be the presence of a stable liquid in which metabolic processes can occur. The study, published in the Proceedings of the National Academy of Sciences, suggests that planets too warm or with atmospheres too thin to support liquid water could still host pockets of these resilient ionic liquids. Future telescopic observations may even be able to detect chemical signatures or pigments indicative of ionic-liquid-based life, expanding the toolkit for astrobiologists. The work by Seager and Agrawal represents a significant paradigm shift, urging a re-evaluation of the definition of a "habitable zone" and broadening the scope of where life might be found in the cosmos.