Alien Life on Some Extrasolar Planets Could Be More Diverse than on Earth

In a new study, University of Chicago researcher Stephanie Olson and colleagues modeled climates and ocean habitats of different types of extrasolar planets using NASA-made software. Their results show that some of these alien worlds may have better conditions for life to thrive than our planet itself has.

An artist’s rendering of potentially habitable exoplanets, plus Earth (top right) and Mars (top center). Image credit: PHL@UPR Arecibo, phl.upr.edu / NASA / ESA / Hubble.

“NASA’s search for life in the Universe is focused on so-called habitable zone planets, which are worlds that have the potential for liquid water oceans,” Dr. Olson said.

“But not all oceans are equally hospitable — and some oceans will be better places to live than others due to their global circulation patterns.”

Life in Earth’s oceans depends on upwelling which returns nutrients from the dark depths of the ocean to the sunlit portions of the ocean where photosynthetic life lives. More upwelling means more nutrient resupply, which means more biological activity.

“These are the conditions we need to look for on exoplanets,” Dr. Olson said.

The team modeled a variety of possible exoplanets, and was able to define which exoplanet types stand the best chance of developing and sustaining thriving biospheres.

“We’ve used an ocean circulation model to identify which planets will have the most efficient upwelling and thus offer particularly hospitable oceans,” she said.

“We found that higher atmospheric density, slower rotation rates, and the presence of continents all yield higher upwelling rates.”

“A further implication is that Earth might not be optimally habitable — and life elsewhere may enjoy a planet that is even more hospitable than our own.”

“There will always be limitations to our technology, so life is almost certainly more common than ‘detectable’ life.”

“This means that in our search for life in the Universe, we should target the subset of habitable planets that will be most favorable to large, globally active biospheres because those are the planets where life will be easiest to detect — and where non-detections will be most meaningful.”

Dr. Olson and co-authors presented the findings August 23 at the 2019 Goldschmidt Conference in Barcelona, Spain.

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S. Olson et al. Exo-Oceanography and the Search for Life in Uncharted Waters. Goldschmidt Abstracts 2019