Space and Orientation

[nforcer06164]

When you're in outer space, a zero-gravity area, and the universe extends almost infinitely in all directions, how can you possibly decide the position you are in relation to everything else? On Earth, there's a center of gravity, and therefore a defined up and down, as well as a north, south, east, and west. In space, there's nothing above you, nothing below you, and nothing really surrounding you. There's no upside-down, no rightside-up, no cardinal direction... so how can it possibly be navigated? How can you move about in such a place when you cannot figure the direction in which you're going? It makes me question space travel, because if you can't orient yourself, can't fixate yourself to some standard position (because none exists), how can it be possible? Thoughts, anyone?