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
Orbit insertion Orbit insertion Orbit insertion is the spaceflight operation of adjusting a spacecraft’s momentum, in particular to allow for entry into a stable orbit around a planet, moon, or other celestial body. This maneuver involves either deceleration from a speed in excess of the respective body’s escape velocity, or acceleration to it from a lower speed. The result may also be a transfer orbit. There is e.g., the term "descent orbit insertion". Often this is called orbit injection. The first kind of orbit insertion is used when capturing into orbit around a celestial body other than Earth, owing to the excess