space doesn't change your weight.
weight is just a measure of the force attracting you to a planet or moon or other body. If you are in space, you are farther from the earth, so it exerts less force on you. Hence, you weigh less.
Actually, your weight is only felt if there is something (like a floor or a spaceship wall, or a rope) keeping you from moving toward the planet. So, if you are in a rocket blasting off, you feel more weight.If you are on a diving jet, you fell less or no weight, because there's nothing keeping you from falling toward the earth.