Purple Archaea may have been the first life forms on Earth, according to a study by molecular biologist Shiladitya DesSarma at the University of Maryland. The research from 2018 explored potential life forms that could have existed on our planet in its early days. Recently, scientists have collected spectral data on 20 species of purple bacteria from various environments, including marshes and deep-sea hydrothermal vents. By measuring the wavelengths of light these bacteria reflect and modeling how these patterns may appear on a distant planet, researchers have created a collection of light signatures that is now part of an ongoing database publicly available for other researchers to use in their own projects.
Astronomers search for signs of life on other planets using biosignatures such as the color of a planet’s surface. Reflected light spectroscopy is often used for this purpose, but current telescopes are limited in their capabilities. For example, the James Webb Space Telescope can only detect biosignatures in an exoplanet’s atmosphere and cannot measure reflected light from the planet’s surface. Edward Schwieterman, an astronomer at the University of California Riverside, emphasizes this limitation.