Nell Greenfieldboyce  

By Nell Greenfieldboyce
NASA's most accurate census yet of near-Earth asteroids suggests that astronomers already know the location of more than 90 percent of the very largest asteroids that could cause mass extinctions. The survey also suggests there are far fewer midsize asteroids than expected, but scientists don't know where most of these are.

By Nell Greenfieldboyce
Once, the U.S. was a magnet for particle physicists, but Europe's Large Hadron Collider is now the biggest show around. As the Tevatron prepares to go dark in September, questions remain about the next step in U.S. physics research.

By Nell Greenfieldboyce
The author of a scientific study suggesting that polar bears have actually drowned swimming long distances to find ice, is under investigation. And some are now questioning the motives behind the investigation.

By Nell Greenfieldboyce
NPR science correspondent Nell Greenfieldboyce toured the facility where the retired space shuttles are being dismantled and prepared for museum displays. 

By Nell Greenfieldboyce
The Alpha Magnetic Spectrometer will collect cosmic rays and was designed to search for antimatter created during the Big Bang. The project was nearly scrapped, but the persistence of one key researcher kept it alive. 

By Nell Greenfieldboyce
Space shuttle Discovery, the workhorse of the shuttle fleet, has carried almost 200 astronauts and numerous science missions to space in its three decades of spaceflight. It launches on its final flight, to the International Space Station, Thursday afternoon.

By Nell Greenfieldboyce
After the Sept. 11, 2001, attacks, the government began imposing curbs on research into pathogens that could be potentially used by terrorists. That has led researchers to quietly destroy valuable specimens of some pathogens for fear of running afoul of legal restrictions.