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More than 3.5 billion years ago, scientists believe, Mars’s climate was warmer and wetter and possibly suited for life. After considering 64 proposed landing sites in all, scientists recommended Jezero as the most promising place to explore.

“Lakes on Earth are both very habitable and inevitably inhabited,” said Kenneth Farley, the mission’s project scientist, during a telephone news conference on Monday. “So that’s the first attraction.”

“The second attraction is that a delta is extremely good at preserving biosignatures, any evidence of life that might have existed,” he added.

Dr. Farley emphasized that the rover is not carrying tools to look for any living microbes, and said that the Martian surface today is too dry, too cold and too bombarded by radiation for microbes to survive.