Space Knight Tekkaman

In 3 years time, the earth will perish due to the pollution. Mankind has to look for a new home, a second Earth. But just as the search for a new home is about to begin, an alien race called the Waldaster attack Earth to conquer it. The Waldaster leader, Dobrai, send his captain Rambos to attack earth but he faces heavy resistance from the Space Knights. The Space Knights are a group of people whose mission it is to find a new home planet and to defend Earth from the Waldaster. This group exists of the scientist Amachi, Joji, Hiromi and the 2 aliens from a planet called Sanno, Andro and Mutan.

Synopsis from Anime News Network