Near-Earth object Near-Earth object A near-Earth object (NEO) is any small Solar System body whose orbit brings it to proximity with Earth. By convention, a Solar System body is a NEO if its closest approach to the Sun (perihelion) is less than 1.3 astronomical units (AU). If a NEO's orbit crosses the Earth's and the object is larger than across, it is considered a potentially hazardous object (PHO). Most known PHOs and NEOs are asteroids, but a small fraction are comets. There are over 19,000 known near-Earth asteroids (NEAs), over a hundred short-period near-Earth comets (NECs), and a number of solar-orbiting spacecraft
Earth orbit rendezvous EDS and Altair would be met by the separately launched Orion (CEV). Once joined in low Earth orbit, the three would then travel out to the Moon and the Orion/Altair combination would fly a lunar orbit rendezvous flight pattern. Earth orbit rendezvous Earth orbit rendezvous (EOR) is a potential methodology for conducting round trip human flights to the Moon, involving the use of space rendezvous to assemble, and possibly fuel, components of a translunar vehicle in low Earth orbit. It was considered and ultimately rejected in favor of lunar orbit rendezvous (LOR) for NASA's Apollo Program of the 1960s and