The sand is pumped underground along with water and other chemicals to extract oil and natural gas trapped deep in rock. But researchers found that air samples taken at some drilling sites contained high enough levels of very fine silica particles to be dangerous to workers.

NASA's newest rover on Mars has just finished analyzing a sample of powder drilled from inside a rock, and has found evidence that the red planet once had conditions that could have supported microbial life.

It's been 40 years since NASA launched Apollo 17, its final human mission to the moon. The commander of that mission says he'd love to give up his claim to fame as "the last man on the moon" but concedes that it probably won't happen in his lifetime. And future trips might be run by companies in the private sector.

Candied yams with a touch of marshmallow cream are what the astronauts on the International Space Station are looking forward to eating for their Thanksgiving feast today. That and a little irradiated smoked turkey, courtesy of NASA.

Charles Monnett's 2006 report on drowning polar bears became a rallying cry for environmentalists. Then he was accused of scientific misconduct. On Friday, he learned he had been cleared.

NASA's newest Mars rover snapped photos of rocky outcroppings that jut out from the alien soil. Scientists say they look like the remnants of an ancient stream bed where water once flowed on the surface of the red planet.

One of the twin space probes launched 35 years ago has traveled more than 11 billion miles from Earth. The Voyager probes were originally slated just to examine Jupiter and Saturn during a five-year trip.

So far everything looks good for a possible docking with the station on Friday by the company's Dragon capsule.

The first of NASA's retired space shuttles will make its way to its new retirement home on April 17. The well-traveled orbiter will be flown low over the nation's capital before being placed on permanent display at the Smithsonian.

Last month, scientists around the world agreed to temporarily halt controversial scientific research with bird flu viruses. Some experts say too little is known about how infectious this virus could be to humans, but other experts think those risks have been blown a bit out of proportion.

In a landmark decision, an expert panel that advises the government on research security says key details of work on the contagiousness of flu viruses should not be published openly. I

The planet, dubbed Kepler-22b, isn't much larger than Earth and is orbiting a star in a region that's not too hot and not too cold — just the kind of place that could be home to liquid water, and maybe even life. But don't pack your bags just yet: It's 600 light-years away.