There is a growing interest in lunar exploration fed by the perception that the Moon can be made accessible to low-cost missions in the next decade. The ongoing projects to set a communications relay in lunar orbit and a deep space gateway, as well as the spreading of commercial-of-the shelf technology for small space platforms such as the cubesats contribute to this perception. Small, cubesat size satellites orbiting the Moon offer ample opportunities to study the Moon and enjoy an advantage point to monitor the Solar System and the large-scale interaction between the Earth and the solar wind. We describe the technical characteristics of a 12U cubesat to be set in polar lunar orbit for this purpose and the science behind it. The mission is named Earth as an exoplanet (EarthASAP) and is submitted to the Lunar Cubesats for Exploration call in 2016. EarthASAP is designed to monitor hydrated rock reservoirs in the lunar poles and to study the interaction between the large Earth’s exosphere and the solar wind in preparation for future exoplanetary missions.