Explore astronomy, from the latest trip to the International Space Station to alien planets outside our solar system.
Shuttles earn their weathering mainly from the searing heat of re-entry.
China had already announced plans to launch two unmanned modules next year, an essential step toward building the space station.
Spacecraft will use its telescopes and other instruments to examine the surface and record gas outbursts.
Robot will complete chores and repairs aboard the International Space Station.
Launch will be shuttle's last as NASA refocuses on deep-space exploration.
Particles created by rockets for space visits remain in atmosphere for years.
Branson said he expects flights for space tourists to begin in nine to 18 months, and he will be among the first passengers.
Douglas Wheelock, who is orbiting the Earth, sent a message from his Twitter account saying he had "unlocked the 'NASA Explorer Badge.'"
Video: Just how big is Earth in comparison to the Sun, stars and other planets?
Two researchers say while a flight to Mars and back is technically feasible now, it would be more cost-effective to launch a one-way trip.
Crash made water on the Moon detectable for scientists.
The galaxy is so ancient that it probably doesn't exist in its earlier form and has already merged into bigger neighbors.
Light from the new record-holder takes roughly 13.1 billion years to reach Earth.
Animal rights advocates are protesting the plans to subject squirrel monkeys to the experiment.
Discovery leads astronomers to rethink what is known about hot Jupiters.
Activist and author blogs about politics, energy and Earth's resources.
Science journalist blogs about humans and other wildlife.