Can We Find Floating Vegetation on Ocean Planets?

Recent advances in astronomical observations have found a significant number of extrasolar planets that can sustain surface water, and the search for extraterrestrial life on such planets is gaining momentum. A team of astrobiologists from Astrobiology Center, National Institute for Basic Biology, and SOKENDAI have proposed a novel approach for detecting life on ocean planets. By conducting laboratory measurements and satellite remote sensing analyses, they have demonstrated that the reflectance spectrum of floating vegetation could serve as a promising biosignature. Seasonal variations in floating vegetation may provide a particularly effective means for remote detection.The results of this research will be published in the journal Astrobiology on February 2, 2025.

Astronomical surveys have discovered nearly 6,000 exoplanets, including many habitable planets, which may harbor liquid water on their surfaces. The search for life on such planets is one of the most significant scientific endeavors of this century, with direct imaging observation projects currently under development.

On Earth-like planets, the characteristic reflectance spectrum of terrestrial vegetation, known as “vegetation red edge”, is considered as a key biosignature. However, ocean planets, with most of their surfaces covered by water, are unlikely to support terrestrial vegetation. To broaden the scope of life detection on ocean planets, this study examined the characteristics of reflectance spectra from floating plants and tested their detectability.

Read more at National Institutes of Natural Sciences

Image: An illustration depicting seasonal changes in floating vegetation and the resulting periodic changes in water surface reflectance. It is expected to become a novel indicator in searching for life on ocean planets. (Credit: Astrobiology Center)