Leaving Earth: Overcoming gravity, slingshot effect, orbiting distance between objects in the solar system.
Living in space is not as easy as it looks in the movies or on TV. Think about what you learned in the last lesson about how different the temperatures and atmospheres were on other celestial bodies. The distance from the Sun affects how much solar radiation arrives at that planet or object. Too much solar radiation can kill humans if they do not have protection from the radiation.