Could a reactionless, gravity-defying propulsion system actually work? A former NASA engineer says yes, but scientists are ...

This new propulsion system could rewrite the rules of spaceflight—not to mention completely defy conventional physics.

Smaller bodies of water, like lakes and pools, don't have noticeable tidal bulges because they lack enough liquid to create pressure that can visibly overcome the pull of Earth's gravity.

ISS crew members and must physically exercise about two hours every day to protect their muscles and bones that are counteracted by the absence of Earth's gravity.

NASA identifies five significant risks that could hinder a successful manned mission to Mars, including cosmic radiation and psychological challenges.

Getting high enough to escape Earth's atmosphere takesa massive amount ... So gravity pulls everything downwards,all the time, but we can overcome gravity if we have enough force inthe opposite ...