You are in space right now, you just happen to have 100km of atmosphere above you. When we say "go to space" we really mean "go to orbit". To go to orbit, you n

You are in space right now, you just happen to have 100km of atmosphere above you. When we say "go to space" we really mean "go to orbit". To go to orbit, you need tangential velocity to get away from the body you're currently attracted to. We use rockets to gain that velocity because no other technology we know of can provide it with the required thrust/weight ratio.