Chang’E-2 satellite asymmetric-descent orbit control technology

Abstract

To accomplish high-resolution imaging of the preselected landing area, it was necessary for the Chang'E-2 mission to perform orbital maneuvering on the far side of the moon to meet the conditional height requirement of the imaging area. Engine shutdown would be executed invisibly on the back side of the moon if the descent maneuver mode opposite to the target perilune or the fuel optimal maneuver mode was used. To ensure the satellite safety, the project collectivety required that the engine shutdown should be designed to be executed in the domestic segmental arcs and meet the requirement of satellite emergency treatment simultaneously. Accordingly, the asymmetric-descent orbit control technology was adopted by offsetting the maneuver point, which obtained the orbit control parameters of finite-thrust mode with an iteration algorithm and modified the results with target perilune drift estimation. The Chang'E-2 satellite declined to the target of 100 km×15 km orbit successfully on 26 October 2010, and has been flying for 32 circles in the experimental orbit to accomplish the preselected landing area imaging. This paper describes the mechanism and realization method of the asymmetric-descent orbit control technology and evaluates the maneuver effect with the actual mission data.Chang'E-2 mission, asymmetric-descent orbit control, perilune drift, preselected landing area imaging Citation:Zhou J L, Liu Y, Peng D Y, et al. Chang'E-2 satellite asymmetric-descent orbit control technology.

Orbit Design Elements of Chang’e 5 Mission

“…By reviewing past experiences, it is found that there are two key elements in the orbit design for precision landing on the Moon, namely, a two-to-two targeting maneuver for achieving the desired perilune altitude and landing latitude, and an orbit plane adjustment or a phasing maneuver for achieving the desired longitude of the landing site. Concurrently, it is essential to use a high-fidelity descent dynamic model and have accurate knowledge of the guidance law in the design process to accurately compute the nominal descent range [10,11].…”

“…To achieve precision landing at the desired landing site, the lander needs to be at the correct AOL and altitude when it reaches the descent point. This can be achieved using a two-to-two targeting maneuver, and the descent altitude is typically specified to be 15 km from the lunar surface at periselene [11].…”

“…The subtractions of Equation ( 12)−Equation (11) and Equation (13)−Equation (11) give the following:…”

Review of the Precise Orbit Determination for Chinese Lunar Exploration Projects

“…During the orbiting mission, this orbiter conducted 7 m resolution image acquisition from the spacecraft at a height of 100 km to generate a high‐resolution global DEM (Ren et al., 2019). The orbit of the spacecraft was adjusted to an ellipsoid orbit, with a perilune height of 15 km and an apolune height of 100 km to collect additional imagery in preparation for the Chang’e 3 lander and rover (Zhou et al., 2011).…”

Review of the precise orbit determination for Chinese lunar exploration projects

“…During the orbiting mission, this orbiter conducted 7 m resolution image acquisition from the spacecraft at a height of 100 km to generate a high-resolution global DEM (Ren et al, 2019). The orbit of the spacecraft was adjusted to an ellipsoid orbit, with a perilune height of 15 km and an apolune height of 100 km to collect additional imagery in preparation for the Chang'e 3 lander and rover (Zhou et al, 2011).…”