Twin of NASA's Perseverance Mars rover begins terrain tests

On a recent day in November, the car-size rover rolled slowly forward, then stopped, perched on the threshold of a Martian landscape. But this rover, named OPTIMISM, wasn't on the Red Planet. And the landscape was a boulder-strewn ...

Scientists discover how mitochondria import antioxidants

Many of the processes that keep us alive also put us at risk. The energy-producing chemical reactions in our cells, for example, also produce free radicals—unstable molecules that steal electrons from other molecules. When ...

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