Near-Earth object its mission, Rosetta was crashed into the comet′s surface in 2016. 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
Earth observation satellite to get the desired global coverage while the relatively constant geometry to the Sun mostly is an advantage for the instruments. The "frozen" orbit is selected as this is the closest to a circular orbit that is possible in the gravitational field of the Earth. Terrain can be mapped from space with the use of satellites, such as Radarsat-1 and TerraSAR-X. Earth observation satellite Earth observation satellites or Earth remote sensing satellites are satellites specifically designed for Earth observation from orbit, similar to spy satellites but intended for non-military uses such as environmental monitoring, meteorology, map making etc. The first