Alien Conquest is a theme released in May 2011. The theme features a large invasion force of aliens attacking earth and attempting to steal all the brainpower from the humans, a first for LEGO. This is the first Space theme to use this premise, with preceding Space themes involving astronauts battling aliens on other planets or meeting more friendly alien lifeforms, such as Martians. This will be the second line of sets released in 2011 with a Space ethos; the other as a subtheme of City. The team of astronauts is known as the ADU, or "Alien Defence Unit".