Joe Palca

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Small drones can do big jobs: Firefighters can use them to find hot spots in blazes, environmental monitors can find the source of hazardous chemical leaks. One just delivered a human kidney for transplant surgery.

But it takes lots of power to spin four helicopter blades fast enough to keep a quadcopter-type drone in the air. Most can only stay aloft for about 30 minutes.

A team of astronomers led by an undergraduate student in Texas has discovered two planets orbiting stars more than 1,200 light-years from Earth.

Astronomers already knew of about 4,000 exoplanets, so finding two more might not seem like huge news. But it's who found them and how that's getting attention.

Is there an efficient way to tinker with the genes of plants? Being able to do that would make breeding new varieties of crop plants faster and easier, but figuring out exactly how to do it has stumped plant scientists for decades.

Now researchers may have cracked it.

Modifying the genetics of a plant requires getting DNA into its cells. That's fairly easy to do with animal cells, but with plants it's a different matter.

Opportunity lost.

NASA has officially declared an end to the mission of the six-wheeled rover on Mars. Opportunity lost power in a dust storm last June, and all efforts to make contact have failed.

"Our beloved Opportunity remained silent," Thomas Zurbuchen, associate administrator for NASA's Science Mission Directorate, said Wednesday at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "With a sense of deep appreciation and gratitude," he added, "I declare the Opportunity mission as complete."

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