‘Surprising’ discovery suggests more variety of life on exoplanets than Earth

23 Aug 2019

Image: © merabi/Stock.adobe.com

Exoplanets with the right ocean circulation patterns could offer a greater variety of life than what we have on Earth, according to new research.

Dr Stephanie Olson of the University of Chicago has said her team’s research into what other worlds may look like has returned a “surprising conclusion”. Presenting her findings at the Goldschmidt Geochemistry Congress in Barcelona, Olson said there is evidence to show that some exoplanets may have better conditions for life to thrive than our own planet.

Reaching across light years with remote sensing tools, the research showed that this increased biodiversity could occur with favourable ocean circulation patterns that would create a more bountiful planet.

“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,” 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.”

Olson and her team modelled likely conditions on exoplanets using ROCKE-3D software developed by NASA to simulate the climates and ocean habitats on a whole number of exoplanet variants.

The conditions we need to look for on exoplanets

One of the key indicators of potential life on a planet that the team was looking for in potential alien oceans was something called upwelling. On Earth, this process returns nutrients from the deepest depths of an ocean to the higher reaches that receive sunlight and where photosynthetic life lives.

“More upwelling means more nutrient resupply, which means more biological activity,” Olson said. “These are the conditions we need to look for on exoplanets.”

In trying to identify which type of exoplanets stand the best chance of having a thriving biosphere, the team found that ones with higher atmospheric density, slower rotation rates and the presence of continents all yield higher upwelling rates.

Earth does not fall into this ideal category, meaning it is possible that there are planets more hospitable than our own.

“We should target the subset of habitable planets that will be most favourable 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,” Olson said.

With the number of exoplanet discoveries numbering in the thousands, the team hopes that its research will help inform future telescope design so that they could look for the tell-tale signs of a potentially biodiverse planet.

Colm Gorey was a senior journalist with Silicon Republic