Ann Nesbitt, Age 13, Of Staten Island, N.Y., for her question:

What causes weightlessness?

A space traveler becomes weightless when he escapes the pull of the earth's Gravity, for it is the force of gravity which gives weight to an object on the surface.  Of the earth. This force becomes weaker with distance. The farther we get from the Earth, the less we feel its gravity and the less we weigh. At a certain distance from the earth, the force of gravity is so slight that a Person seems to have no weight at all. A space traveler then becomes weightless, for the force of gravity no longer pulls his body toward the center of the earth.