Alien craft flew by the Earth and nothing would have happened, but they accidentally hooked artificial satellite and decided to decipher his message. After reviewing the information about the people, the aliens decided that we - underdeveloped civilization, which is easy to grab and sent an army to conquer the territory of starships. You - the only hope for the salvation of mankind, and at your disposal truck with a rocket launcher out of date, it is slow and unwieldy, but it does not prevent you drive out the aggressor and the Earth. Shoot without giving them land and destroy you.