A recent study by planetologist Robin Wordsworth from Harvard University and astrobiologist Charles Cockell from the University of Edinburgh proposes that life could potentially exist in the universe even in the absence of planets. Published in the journal Astrobiology, the research challenges the conventional notion that habitability depends solely on planetary environments.
The researchers argue that ecosystems might independently generate and sustain the necessary conditions for life, such as temperature, pressure, and humidity. They explain that biological structures and barriers could replicate the planetary conditions essential for life.
Examples from Earth, including cyanobacteria, Arctic algae, and Sahara ants, illustrate how living organisms adapt to extreme environments. The authors suggest that similar biological barriers in space could allow light for photosynthesis while blocking harmful ultraviolet rays, preventing the loss of volatile substances, and maintaining appropriate temperature and pressure for liquid water.
They propose that these biological barriers could allow for habitable conditions within 1 to 5 astronomical units in the solar system, where one astronomical unit is the average distance from the Earth to the Sun, approximately 149 million kilometers.
The authors conclude that a completely autonomous system capable of regeneration and growth is not constrained by any physical or chemical limitations, warranting further consideration. They posit that life could evolve in ways distinct from Earth, potentially leading to habitats outside traditional habitable zones around other stars, where unusual but detectable biosignatures might exist.