There's more evidence that water once flowed on Mars with the discovery of an ancient river delta deep below the surface. NASA's Perseverance rover found it more than 35 meters beneath Jezero Crater using ground-penetrating radar. Perseverance was launched in 2020 to search for signs of ancient life on the red planet. Since landing in February 2021, it has been exploring Jezero Crater and collecting rock samples.

The crater, which is approximately 45 kilometers (28 miles) in diameter, lies north of the Martian equator and was formed by an asteroid impact almost 4 billion years ago. NASA chose this spot to explore because numerous geological features suggest that water once flowed here and may have supported ancient life, specifically, a part of the crater called the Margin Unit. This area is packed with carbonates, which on Earth, usually form in stable aqueous environments, such as shallow seas or lakebeds.

The new research is published in the journal Science Advances and is based on data from 78 traverses of the area from September 2023 to February 2024.