Summary:

- The article discusses evidence that Mars once had an ancient ocean, based on the discovery of delta deposits in the Valles Marineris canyon system.
- Researchers analyzed satellite images and data from the Mars Reconnaissance Orbiter to identify these delta deposits, which are typically formed by the deposition of sediments at the mouth of a river flowing into a body of water.
- The presence of these delta deposits suggests that Mars had a large, stable body of water in its past, providing insights into the planet's ancient climate and potential for habitability.