2024-04-19 16:14:26
Infrared-fed bacteria are found in many niches on Earth – especially in places where sunlight does not reach: for example, in murky swamps or deep hydrothermal vents. In a new study published on April 16 žurnale „Monthly Notices of the Royal Astronomical Society“Cornell University astrobiologist Lígia Fonseca Coelho and her co-authors grew a sample of these bacteria, measured the wavelengths of light they reflected, and modeled what these light signatures would look like on various distant worlds.
The researchers say that it will be possible to search for such light spectra with telescopes such as the Extremely Large Telescope under construction in Chile. Extremely Large Telescope) and the Observatory of Habitable Worlds (eng. Habitable Worlds Observatory).
“We need to create a database of signs of life so that our telescopes don’t miss life if it doesn’t happen to look like what we see around us every day,” says one of the authors of the studyCornell University astronomer and director of the Carl Sagan Institute, Lisa Kaltenegger.
Purple is the new green
Purple bacteria belong Pseudomonadota to a group of bacteria in the genus, and they thrive in low-oxygen environments. LF Coelho and colleagues cultivated 20 species of purple sulfur-producing bacteria and 20 species of purple non-sulfur-producing bacteria. The researchers collected these species from a variety of environments, including pre-existing laboratory colonies, waters near Cape Cod in Massachusetts, and a pond on the campus of Cornell University in New York state. These bacteria actually have many other color pigments besides purple, including orange and red carotenoids.
After determining the wavelengths of light reflected most strongly by these bacteria, the researchers simulated what those waves would look like from various possible exoplanets: an Earth-like environment with 70 percent oceans and 30 percent land, 100 percent an ocean world, 100 percent, a frozen world or a snowy world that is half land and half snow.
“Our models suggest that, depending on the biota and cloud cover, a variety of terrestrial planets could have signatures of purple bacterial surface biopigments,” the researchers write in the paper. “While it’s not known whether life – or purple bacteria – could develop on other worlds, purple may just be the new green in the search for surface life.”
2024-04-19 16:14:26