China launches Chang’e 5-T1 test probe as precursor to 2017 lunar sample return mission
On Thursday, Oct. 24 China launched the Chang’e 5-T1 spacecraft on a demonstration mission to orbit the Moon and return to the surface of the Earth as part of its Lunar Exploration Program. The Chinese Long March 3C launch vehicle lifted off at 2 p.m. EDT (2 a.m. local time) from the Xichang Satellite Launch Center, which lies in the Sichuan province. This flight serves to test the various systems on board such as guidance systems and the heat shield, paving the way for the future lunar sample return mission.
Chang’e 5-T1 separated successfully from the rocket, entering Earth orbit shortly thereafter. The spacecraft will now embark on a journey to fly around the far side of the Moon and use lunar gravity to return to Earth traveling at nearly 25,000 mph (approximately 40,000 km/h). The planned eight day mission will conclude with the spacecraft using a skip reentry approach before landing in the Inner Mongolia region of China.
Skip reentry is a method of reentry that “bounces” a spacecraft off of the top layers of Earth’s atmosphere prior to the final reentry phase in which the spacecraft returns to the Earths’ surface. This method can be compared to skipping a rock along the surface of a river or lake, where the rock is slowed during the times when it is in the water; gradually slowing so much that it falls into the water (hence the name).
The spacecraft dips into the atmosphere to slow down and then returns to a higher orbit before making its final approach into the atmosphere. By slowing down before final approach, the temperatures seen during reentry are not as intense since some of the energy of the spacecraft has already been dissipated. The technique is technically challenging since the angles used to skip along the atmosphere must be precise, otherwise the spacecraft can “skip” into outer space or come in at too steep of an angle resulting in its destruction.
According to Xinhua: “The mission is to obtain experimental data and validate re-entry technologies such as guidance, navigation and control, heat shield and trajectory design for a future touch-down on the moon by Chang’e-5, which is expected to be sent to the moon, collect samples and return to Earth in 2017.”
The launch yesterday was part of a three-step Lunar Exploration Program that China will conclude in 2017 with the sample return mission. The missions in this program carry the name Chang’e, who is the Chinese goddess of the Moon. The first two missions, Chang’e 1 and Chang’e 2, successfully completed the orbiting phase of the program in 2007 and 2010, respectively.
The second phase objectives include soft landings and robotic rover exploration of the Moon. This phase is comprised of the Chang’e 3 and Chang’e 4 missions. The Chang’e 3 mission conducted in 2013 included a robotic rover, named Yutu, which explored the lunar surface until experiencing mechanical difficulties but is still returning valuable data from the Moon’s surface. The Chang’e 4 mission will also include a robotic rover and is currently scheduled for 2015.
The third and final phase of the Lunar Exploration Program will be accomplished on the Chang’e 5 mission with the return of approximately 4.4 pounds (2 kilograms) of lunar soil. This mission would make China the third country in the world to accomplish a lunar soil return mission, with Russia and the United States being the other two.
In addition to the Lunar Exploration Program, China is currently also developing its human spaceflight efforts by a building a space station in low-Earth orbit. The Tiangong-1 space station was launched in to orbit in 2011 and remains there after having multiple crews visit the floating laboratory. Tiangong-1, whose name means “Heavenly Palace”, enabled China to practice rendezvous and docking procedures as well as allowing taîkonauts, the name for Chinese astronauts, to conduct extended stays on orbit. There are plans for future larger, modular space stations over the next decade.
Jason Rhian spent several years honing his skills with internships at NASA, the National Space Society and other organizations. He has provided content for outlets such as: Aviation Week & Space Technology, Space.com, The Mars Society and Universe Today.