Tucson Standard

The University of Arizona is leading research into the potential of next-generation telescopes to detect biosignatures on distant planets. These signs could indicate past or present life, including specific molecules and isotopes. A recent study in the Astronomical Journal examines how two major telescopes under construction in Chile, the U.S. Giant Magellan Telescope and the European Extremely Large Telescope, might revolutionize the search for extraterrestrial life.

The study is centered around the "habitable zone oxygen hypothesis," which suggests that planets within a star's habitable zone are more likely to have significant atmospheric oxygen, potentially signaling life. Kevin Hardegree-Ullman, formerly a postdoctoral associate at the University of Arizona Steward Observatory and now a staff scientist at NASA Exoplanet Science Institute, led this research.

Hardegree-Ullman explained that the study aimed to plan for upcoming giant telescopes by conducting simulations to understand what kind of science can be performed with them. "One of the main promises of these extremely large telescopes...is discovering signs of life on exoplanets," he said.

The study found that detecting oxygen will be challenging but possible using direct imaging with high-resolution spectroscopy. This method involves blocking most light from a star to see its fainter planets. Proxima Centauri b, an exoplanet orbiting our closest neighboring star, will be a primary target for direct imaging.

Hardegree-Ullman noted that modern spectrographs can split light into distinct colors or wavelengths to reveal an exoplanet's atmospheric composition. He emphasized the need for precise instruments and funding: "If we want to be the first to detect potential signs of life out there, we need to start building these instruments now."

The survey simulation anticipates observing multiple Earthlike exoplanets over ten years. The GMT is expected to survey five to seven such planets for Earthlike oxygen levels, while ELT could survey three times more due to its greater light-collecting power.

Both telescopes being in Chile allows them to independently verify each other's findings and potentially combine signals for faster observations. Hardegree-Ullman stressed making a convincing case for telescope time: "We want to survey many planets...the search for life out there is one of the biggest goals."

Regarding specific Earth-like exoplanets with biosignatures, Hardegree-Ullman stated they don't yet have an ideal candidate but mentioned Proxima Centauri b as a promising target. Most suitable targets orbit M dwarf stars, which pose challenges due to their characteristics like star spots and flares.

Ongoing searches aim to find more Earthlike planets as crucial future targets for biosignature searches.