For decades, the standard perception of Mars has been almost black-and-white in its simplicity—or rather red and blue: There is the barren, freeze-dried and rust-ruddy planet of today. And eons ago, there was a world warmer, wetter and more aquamarine with rivers, lakes, oceans and perhaps even life on its surface. In this red-and-blue view of Mars is much like a coin, with scientists questing to understand what caused the great planetary flip between its two opposing sides. Yet the closer they look, the clearer it is that this crude dichotomy cannot be entirely true: Mars, like Earth, is and always has been many worlds in one. The story of its habitability may be best understood not as a single, one-way global shift between red and blue but instead a series of hopscotch skips across a motley, regional patchwork of complex, changing conditions.
“It’s very easy to see Mars as one thing at one time,” says Matt Balme of the Open University, based in England. “But there were locations that were warm, wet, cold and dry, all at once.”
A research paper published today in the journal Science highlights this more nuanced view in exquisite detail. (Balme was not involved with the work.) It reports initial results from an in situ visual survey of the “Octavia E. Butler” landing site of NASA’s Perseverance rover, which touched down in Jezero Crater in February. Mission planners chose Jezero because orbital images suggested it harbors an ancient river delta and lake system sculpted by flowing water billions of years ago. Now analysis from Perseverance has not only confirmed this to be true but has also discovered short-lived episodes of sudden change that happened there.
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