The humans are a group of astronauts that have journeyed to Mars in search of powerful yellow-green energy crystals found on the Martian surface. In the storyline, the humans are mining the crystals for a new source of energy, as Earth is experiencing an energy crisis. Unfortunately for the Astronauts, the Aliens are also seeking the crystals for themselves. The human structures consist of two colours: orange and white. They have the "Classic Space symbol". There were a range of Astronaut members in the Mars Mission theme; according to LEGO Battles, the Astronauts were led by the Astro Commander, a leader of the Astronauts in the game who appeared during cutscenes. The expedition was then followed by two commandos named Biff and Gemma.