Astronauts and space tourists may rhapsodize about feeling weightless during spaceflight, but don't be fooled by the somewhat misleading term "zero-gravity." Every object in space still feels the gravitational pull from other objects, including space travelers who imagine themselves free of Earth's gravitational shackles.
Earth's gravity affects everything at or near the planet's surface. We feel the force of gravity on Earth through our mass, and that force also translates into a downward pull of 9.8 meters per second squared (32 ft/s^2).
That's why astronauts need powerful machines such as the space shuttle's main engines and twin boosters or the Russian Soyuz rockets to travel beyond Earth's immediate gravitational tug.
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