A clear science explanation of why astronauts appear weightless while orbiting Earth. It breaks down gravity free fall and orbital motion showing how astronauts and spacecraft are constantly falling ...

As humans begin to colonize space, it's inevitable that some will suffer a cardiac arrest. Space CPR conducted in weightlessness will be crucial to save their lives -- and researchers say they've now ...

A moon rock brought to Earth by Apollo 11, humans' first landing on the moon in July 1969, is shown as it floats aboard the International Space Station. Part of Earth can be seen through the window.