Chang'e 3

Chang'e 3 was a robotic lunar exploration mission conducted by the China National Space Administration, marking China's first soft landing on the Moon and the first lunar soft landing by any entity since the Soviet Union's Luna 24 in 1976. The mission, named after the Chinese mythological moon goddess, deployed the Yutu rover, making China the third country to achieve this feat after the Soviet Union and the United States. Launched in December 2013, it represented a major technological leap for the Chinese Lunar Exploration Program and conducted extensive in-situ scientific investigations in the Mare Imbrium region.

Mission overview

The primary objectives of the mission were to demonstrate key technologies for soft landing and roving on the lunar surface, and to conduct direct, long-term scientific exploration. The mission was launched on 1 December 2013 atop a Long March 3B rocket from the Xichang Satellite Launch Center. After a transit of approximately 112 hours, the spacecraft entered a 100 km circular lunar orbit on 6 December. Following orbital adjustments and careful site selection, the lander successfully touched down on 14 December in a region of Mare Imbrium named Sinus Iridum. The mission was part of the second phase of the Chinese Lunar Exploration Program, following the orbital missions Chang'e 1 and Chang'e 2, and laid crucial groundwork for the subsequent Chang'e 4 and Chang'e 5 sample-return missions.

Spacecraft design

The Chang'e 3 spacecraft consisted of two main components: a stationary lander and the Yutu rover. The lander, with a four-legged structure, was equipped with a variable-thrust engine for the powered descent phase, guided by laser and optical imaging sensors for hazard avoidance. The Yutu rover, with a mass of approximately 140 kg, was a six-wheeled, solar-powered vehicle designed for a three-month operational life. Both lander and rover carried independent communication systems for direct links with Earth via the Deep Space Network and relay through Chinese tracking stations like the Jiamusi Deep Space Station. The lander also featured a radioisotope heater unit to survive the extreme cold of the lunar night.

Scientific payload

The lander carried four primary instruments: the Landing Camera, the Terrain Camera, an Extreme Ultraviolet Camera for observing Earth's plasmasphere, and a Moon-based ultraviolet telescope for astronomical observations. The Yutu rover was equipped with a sophisticated suite including a Panoramic Camera, a Visible and Near-Infrared Imaging Spectrometer for mineralogical analysis, an Alpha Particle X-ray Spectrometer for elemental composition, a Ground-Penetrating Radar to probe the lunar subsurface structure, and an Active Particle-induced X-ray Spectrometer. This payload was designed to study the lunar soil, geology, and subsurface structure, as well as the space environment from the lunar surface.

Landing and surface operations

The powered descent sequence began from an altitude of 15 km, with the lander using its main engine to reduce velocity. During the final 100 meters, the craft hovered to select a safe landing site using its hazard avoidance system before touching down softly in Mare Imbrium. The Yutu rover was deployed onto the surface via a ramp approximately seven hours after landing. The rover conducted traverses and scientific measurements during the lunar day, entering a dormant state during the lunar night. While the rover experienced a mechanical control anomaly during its second lunar night, ending its mobility, it continued to function as a stationary science platform for an extended period, far exceeding its designed lifespan.

Scientific results and discoveries

The mission yielded significant scientific data, fundamentally altering understanding of the local lunar region. The Ground-Penetrating Radar revealed a multi-layered subsurface structure, identifying at least nine distinct layers of regolith and basaltic lava flows, providing a new geological history for Mare Imbrium. The Alpha Particle X-ray Spectrometer and Visible and Near-Infrared Imaging Spectrometer analyses identified a new type of basaltic rock with unique mineralogical composition, distinct from samples returned by the Apollo program and Luna programme. Furthermore, the Moon-based ultraviolet telescope conducted the first long-term astronomical observations from the lunar surface, and the lander's instruments directly detected helium-3 in the solar wind implanted in the regolith.

Category:Chinese Lunar Exploration Program Category:2013 in spaceflight Category:Missions to the Moon Category:Spacecraft launched in 2013