Loud applause filled the mission control center as China joined the exclusive club of countries who have performed a successful soft landing on the surface of the moon (joining the United States and the former Soviet Union). The Chang'e-3 module touched down on the lunar surface on Saturday, December 14 after a two-week journey, beginning at the Xichang Satellite Launch Center. It is the first moon landing since 1976, when the sample return mission of Luna 24 was carried out by the Soviet Union.
The journey consisted of a series of carefully staged steps, starting with an entry into an orbit 62 miles above the lunar surface. The orbit was modified into an elliptical orbit four days afterward, with the low point at a mere 9.3 miles from the surface. During final descent, a variable-thrust engine was activated to control the speed and direction, with the main engine shutting down for the final free fall of several feet.
A series of sensors allowed the flight computer to effectively "choose" its own level, unobstructed landing site. Images of the touchdown process were continuously transmitted from a downward-facing camera. Chang'e settled on a spot near Sinus Iridium (also known as the Bay of Rainbows) and promptly deployed the solar panels it needs to generate electricity for its systems and analytical cargo.
The module contains observational instruments such as an extreme-UV camera, telescope, and stereo imager. To protect these instruments from the incredibly harsh environment, the unit also contains a thermoelectric generator powered by radioisotopes to provide heat to their working area. Otherwise, the incredibly low temperature approaching -180°C would damage the instrument's electronics during the nights (which last two weeks on the moon). The ability to withstand the harsh environment at night and provide usable data during the day will be a significant test of Chang'e's abilities.
Chang'e represents another step forward by being the first lunar landing ever to include a landing module and a rover. The small six-wheeled rover, known as Yutu ("Jade Rabbit"), can navigate the surface of the moon and examine the lunar surface to a depth of approximately 300 feet using ground-penetrating radar. Yutu also contains cameras for observation and feedback of images during its travels. During its journey through space, the rover was mounted on top of the lander. It was lowered to the surface on Sunday, December 15th and has begun its independent journey over the lunar surface.
China's space program intends to follow up this work with a mission designed to return soil and rock samples to Earth for more detailed analysis. Ouyang Ziyuan, who serves as a senior adviser within the lunar probe program, believes that research on these samples can be achieved within two to three years.
As China attempts to establish itself as a major player in space exploration, the successful landing of Chang'e and launch of the Yutu rover represents a significant step forward. The lessons learned during this mission may pave the way for more ambitious space missions, and perhaps even manned missions, in the future.