What is it about?

The discovery of rivers on other planets has been one of the most exciting in the history of solar system exploration. The presence of rivers on Mars and Titan is important not only because it shows that both worlds have familiar landforms, but also because rivers can provide a wealth of information about the environments where they form. There is, however, a fundamental roadblock that has stalled efforts to understand rivers on Mars and Titan: a lack of field measurements. With no in situ measurements of active flow on Mars (where the dormant riverbeds have been eroding for billions of years) or Titan (where the flows are not yet accessible to spacecraft) and no field data for the vast majority of Earth’s rivers, estimates of flow, sediment transport, and other environmental characteristics – such as the longevity of potentially-habitable crater lakes on Mars, or rates of methane rainfall on Titan – are on shaky ground. We therefore developed a technique that accounts for differences in gravity and materials and lets us estimate a river's flow rate using only measurements made from orbit.

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Why is it important?

On Earth, we use our method to predict sediment and water fluxes in regions where field surveys are impractical. On Mars, we show that the river deposits explored in situ by NASA’s Perseverance and Curiosity rovers required prolonged time periods when conditions favorable for life were maintained. On Titan, we show that its active methane rivers may have substantially different geometry than rivers on Earth. NASA’s Dragonfly mission to Titan can test our predictions and may even detect active sediment transport.


Writing this article and working with all the co-authors was a a lot of fun. We now have a tool that we can use to estimate the fluxes of fluid and sediment in any river on Mars or on Titan, using only measurements of its slope from topography data and its width from images.

Samuel Birch

Read the Original

This page is a summary of: Reconstructing river flows remotely on Earth, Titan, and Mars, Proceedings of the National Academy of Sciences, July 2023, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2206837120.
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