How is it possible that Rush was able to dial Destiny? Also, for that matter, how is it that the Destiny is able to use its Stargate at all? It's established that the gate has to be calibrated to a specific planet, which was what caused the difficulty with the programming for the Midway Space Station. If the Destiny is constantly flying through space, it should be impossible for the gate to work, unless it is constantly updating for stellar/planetary drift on a second-by-second basis.