Earth&Sky:火星上的礦物質(zhì)說(shuō)明火星上的生命已成過(guò)去

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Bethany Ehlmann: Ancient Mars, like the Earth today, hosted a variety of watery environment.

You are listening to Bethany Ehlmann. Ehlmann led a study that's [----1----] the possibility that life existed on the planet Mars deep in its past. She's on the science team of a NASA mission that looks at minerals on Mars' surface. What Ehlmann found were patches of magnesium carbonate.

Bethany Ehlmann: So carbonate is kind of like a signature mineral of neutral to alkaline pH conditions in the waters from which they've formed.

Scientists have thought that, long ago – 3.5 billion years ago – Mars was intensely acidic and [----2----] to much possibility for life. But Ehlmann's study suggests otherwise. We asked her why….

Bethany Ehlmann: Because carbonate tends to dissolve in acid. And the fact that we see carbonate persisting to the present means that it never experienced these acid conditions, and instead it preserves the record of ancient Mars that was neutral to alkaline pH, and perhaps more [----3----] to life.

The carbonate is similar to limestone on Earth. And like limestone fossils, fossils of early Martian life might be preserved in the carbonate found on Mars.

Bethany Ehlmann: Well, [----4----]

Ehlmann added that future landed missions to Mars might answer questions of whether life ever existed on the [----5----] planet.

I'm Jorge Salazar from E&S, a clear voice for science. We are at E&S. org.

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