Researchers: ocean planets different from Earth could sustain alien life

It’s no secret that humans have long been searching for life outside our planet. Whether it’s looking to our nearby red neighbor or for rocky planets like Earth in other solar systems and galaxies, scientists have been keen on finding any signs of extraterrestrial life.

A new study from the University of Chicago and Penn State University could mean researchers no longer need only continue looking for signs of life on planets that emulate our own.

In a study published in the Astrophysical Journal, researchers Edwin Kite and Eric Ford found that “water world” planets could potentially maintain surface conditions like Earth that could make them a “sweet spot” for habitability.

“Earth has been habitable for billions of years, but we don’t know exactly why it is,” Kite, assistant professor of geophysical sciences at the University of Chicago and lead author of the study, said. 

When studying the reason for life on Earth, scientists have used the cycling of minerals and gases between Earth’s atmosphere, oceans and mantle through volcanic and plate tectonic processes as the reason for long-term habitability. 

As a result, most of the scientific community believed that the geochemical cycling was needed for evolution of advanced life on planets and therefore, deep global oceans would prevent the cycling of those minerals and gases that keep climate stable on Earth and possible to sustain life.

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“Geochemical cycling is key for our planet, but it’s not necessarily necessary for others,” Kite said.

By conducting more than a thousand simulations that model the formation of rocky planets as well as the planet’s evolution, meaning temperature and chemistry of oceans and atmospheric changes over time, Kite and Ford wanted to find if life could be present on planets which are very different from Earth and that have water which could even be hundreds of miles deep on the planet’s surface.  

Having deep oceans provides really large reservoirs that could help regulate a planet's climate, Ford, Penn State professor of Astronomy and Astrophysics and co-author of the study, said. 

Researchers worked together to study the amount of water delivered to rocky planets as well as tracking the carbon dioxide as it moved between the planet’s ocean, atmosphere and rocks during its early years.

"I focused on the formation of planets and the history of how they grow and Edwin focused on modeling the geophysics of the planets," Ford said. 

By tracking the amount of water and evolution of rocky planet’s climates over billions of years through the simulations, Ford and Kite concluded that the simulations suggested water world planets could remain in the habitable zone for more than a billion years, despite not having geochemical cycling or plate tectonics like on Earth.

Having these large reservoirs on the ocean planets could be favorable to sustaining life for a long time, Ford said. 

The simulations already conducted were based on focusing on planets that orbited stars like our own,  planets orbiting low-mass, red dwarf stars could also be potential candidates for hosting life. Researchers will be using the Habitable Zone Planet Finder built at Penn State's Center for Exoplanets to search for planets orbiting red dwarf stars since the planet it discovers will be some of the best candidates to search for biosignatures.

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“We have already detected thousands of exoplanets, but we don’t have all the information on them,” Kite said.

Using NASA’s James Webb Space Telescope, which is expected to launch in 2021, and grounded laboratories such as the Habitable Zone Planet Finder, researchers will be able to conduct data to see if these ocean planets are habitable for life or if they already host life.

"There is a lot of interest in answering basic questions of the origin of our solar system and of life," Ford said. "What science helps us answer is if life is a once in a galaxy phenomenon or not." 

Contact Antonia Jaramillo at antoniaj@floridatoday.com or 321-242-3567. Follow her on Twitter at @AntoniaJ_11.