Exploration of Jupiter its first Large mission, replacing its contribution to EJSM, the "Jupiter Ganymede Orbiter" (JGO). The partnership for the Europa Jupiter System Mission has since ended, but NASA will continue to contribute the European mission with hardware and an instrument. The "Europa Clipper" is a mission proposed to NASA to focus on studying Jupiter's moon Europa. In March 2013, funds were authorized for "pre-formulation and/or formulation activities for a mission that meets the science goals outlined for the Jupiter Europa mission in the most recent planetary decadal survey". The proposed mission would be set to launch in the early 2020s and
Origin of the Moon of the present size of Earth, and another the diameter of Mars (half of the terrestrial radius and a tenth of its mass). The colliding body has sometimes been referred to as Theia, the mother of Selene, the Moon goddess in Greek mythology. This size ratio is needed in order for the resulting system to have sufficient angular momentum to match the current orbital configuration. Such an impact would have put enough material into orbit around Earth to have eventually accumulated to form the Moon. Computer simulations show a need for a glancing blow, which causes a portion of the