Mars likely to remain free of Earth's microbes

Astronauts work in space, or 65 feet underwater

Aerospace pioneer plans private moon base

Hawking reveals realistic ideas for time travel

New solar satellite may help clean up space junk

Space tourism just got a bit cheaper

Scientists eager to find alien life get big boost

Largest telescope ever built planned for Chile

NASA contemplates fate of soon-to-retire space shuttles

NASA's new asteroid mission could avert disaster on Earth

President Obama offers bold new course for NASA

NASA icons blast Obama's new space program plans