Mars' Rivers Flowed Stronger and More Recently Than Previous Estimates A global survey of Mars by Edwin Kite and colleagues concludes that for a given area, the planet's rivers were wider than those on Earth today. Their intense flow may have also persisted as recently as one billion years ago, the researchers say. These findings suggest that climate-driven precipitation may have taken place on Mars even during the time that researchers think the planet was losing its atmosphere and was drying out. The survey by Kite et al. used image data of well-preserved paleo-river channels, alluvial fans and deltas across Mars, and calculated the intensity of river runoff using multiple methods, including an analysis of the size of the river channels. In the river basins for which there are the most data, Mars' rivers were about two times wider than those on Earth. Between 3.6 and 1 billion years ago, and likely after 1 billion years ago, there was intense runoff in these channels, amounting to 3 to 20 kilograms per meter squared each day. The runoff appears to be distributed globally, and was not a short-lived or localized phenomenon. If the dates for these massive rivers are correct, the findings could suggest that Mars' late-stage atmosphere disappeared faster than previously calculated, or that there were other drivers of precipitation under low-atmosphere conditions, the researchers say.