Landing detecting sensor and landing area obstacle detecting method for planetoid detection

The invention discloses a landing detecting sensor and a landing area obstacle detecting method for planetoid detection. The landing detecting sensor comprises an optical system and an electronic system. The optical system emits four measuring light beams to the surface of a planetoid so as to form four measuring points in the surface of the planetoid, wherein the four measuring light beams are located in different directions and every three measuring points are not in the same straight line. The optical system measures the distance information of each measuring light beam. According to the distance information d of the th measuring light beam, an azimuth angle [theta], and a pitch angle [phi], the electronic system acquires a position vector n = d[cos[phi]cos[theta] cos[phi]sin[theta] sin[theta], acquires a plane normal vector intersection angle of every two planes according to the position vector, compares the plane normal vector intersection angles with a predetermined value, and determines that the four measuring points are in the same plane if all plane normal vector intersection angles are less than the predetermined value or otherwise, determines that the four measuring points are not in the same plane. A problem of fast determining the relative distance between the landing detecting sensor and the planetoid and a problem of landing area obstacle detection are solved.