A group of prominent scientists who have been critical of missile defense plans told lawmakers that a system being built by the United States cannot protect the country.
Giant chunks of manmade space junk - like the dead satellite that the U.S. government shot down - regularly fall to Earth. Yet no one has ever been reported hurt by them. Chunks of debris weighing two tons or more from satellites and rocket parts fall uncontrolled every three weeks or so, according to an analysis by a Harvard University astronomer who tracks satellites and space debris.
The U.S. government is researching whether the best defense against a chemical, biological or radiological attack might one day be right in everyone's hands - or on their ears.
The U.S. military is quietly expanding capabilities to attack terrorist computer networks, including websites that glorify insurgent attacks on U.S. forces in Iraq, military officials and experts say.
Homeland Security and Energy department leaders urge cities vulnerable to terrorism to undergo an inventory of all radioactive material within city limits, so authorities can detect "dirty bombs" terrorists might plant.
Astronauts on the International Space Station have been hurling more garbage out the station's back door in recent months. Outdated equipment - some of it expensive - that's not practical for the space shuttle to bring back to Earth is simply being thrown into space.
Renewable energy is gathering steam in several states as voters and governors push electric utilities to generate a set percentage of electricity from clean sources such as wind and solar power.
U.S. President George W. Bush has authorized a sweeping new national space policy, green-lighting an overarching national policy that governs the conduct of America's space activities.
China has beamed a ground-based laser at U.S. spy satellites over its territory, a U.S. agency said, in an action that exposed the potential vulnerability of space systems that provide crucial data to American troops and consumers around the world.
The use of unmanned surveillance planes over Iraq has soared, revolutionizing the way U.S. troops wage war and crowding the skies above Iraq.