The University of Arizona will receive $12 million to lead two new programs in NASA's Interdisciplinary Consortia for Astrobiology Research project.

The programs, which were among eight selected from more than 40 applicants, will focus on the origins of life and the search for habitable planets.

Whether gathering spectral data from thousands of known exoplanets or exploring worlds closer to home, the quest to find life elsewhere requires knowing what to look for. Such is the focus of the Alien Earths team led by Dániel Apai, an associate professor of astronomy and planetary sciences at UA. 

"What would be the signatures that we could look for when we are studying other planets to deduce whether or not they are likely to have life?" Apai asked. 

Data remains limited, so Apai's team combines incomplete information on individual planets with "robust statistical understanding" of how other planets function. They've mainly looked for other Earths — worlds with oxygen and the conditions needed for liquid water.

"Of course, the fact that the planet has an ocean doesn't mean that it is meeting all the requirements to be habitable. There could be other parameters in which the planet is very different from Earth. But it's a very good starting point," said Apai. 

Even on Earth, current ecosystems sprang from past environs that were relatively alien, even hostile. So the Metal Utilization and Selection Across Eons team led by UA astrobiologist Betül Kaçar will study why certain chemical elements, including some metals, are — or aren't —  essential for life.

"While we know a lot about how these elements are used in biology today, there remains an uncertainty about why life selected these elements," Kaçar said.

For example, while nitrogen is essential to life, most organisms rely on microbes to move it from the atmosphere to the life cycle. And those microbes rely on metals that were are or inconsistently available during Earth's prehistory.

"So this is a very interesting conundrum. Does this imply that certain metals are so essential for life as we know it that evolution selected for these elements, despite their scarcity, and therefore the availability of these elements should be a consideration for searching for life? Or does the co-evolutionary history of life and environments on Earth reveal other possibilities?" Kaçar said.

Kaçar's team will approach this puzzle by studying life on early Earth, including studying ancient variants of proteins and microbes in the lab.   

"I utilize multiple experimental systems in order to reconstruct the past biology in the lab. It's almost an exploration of life's history in a flask," Kaçar said.

Both projects involve collaborations with institutes around our world, including Arizona State University.