Chinese Lunar Exploration Program
Encyclopedia
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
undertaken by the China National Space Administration
China National Space Administration
The China National Space Administration is the national space agency of the People's Republic of China responsible for the national space program. It is responsible for planning and development of space activities...
(CNSA), the space agency of the People's Republic of China
People's Republic of China
China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...
. The program makes use of the Chang'e lunar orbiters, lunar rover
Lunar rover
The Lunar Roving Vehicle or lunar rover was a battery-powered four-wheeled rover used on the Moon in the last three missions of the American Apollo program during 1971 and 1972...
s and sample return spacecraft, launched on adapted Long March 3A
Long March 3A
The Long March 3A , also known as the Chang Zheng 3A, CZ-3A and LM-3A, is a Chinese orbital carrier rocket. It is a 3-stage rocket, and is usually used to place communications satellites and Beidou navigation satellites into geosynchronous transfer orbits.It has formed the basis of the Long March...
, Long March 5/E and Long March 7 launch vehicles. Launches and flights are monitored constantly by a Telemetry, Tracking and Command (TT&C) system, which uses 50-m radio antennas in Beijing
Beijing
Beijing , also known as Peking , is the capital of the People's Republic of China and one of the most populous cities in the world, with a population of 19,612,368 as of 2010. The city is the country's political, cultural, and educational center, and home to the headquarters for most of China's...
and 40-m antennas in Kunming
Kunming
' is the capital and largest city of Yunnan Province in Southwest China. It was known as Yunnan-Fou until the 1920s. A prefecture-level city, it is the political, economic, communications and cultural centre of Yunnan, and is the seat of the provincial government...
, Shanghai
Shanghai
Shanghai is the largest city by population in China and the largest city proper in the world. It is one of the four province-level municipalities in the People's Republic of China, with a total population of over 23 million as of 2010...
and Ürümqi
Ürümqi
Ürümqi , formerly Tihwa , is the capital of Xinjiang Uyghur Autonomous Region of the People's Republic of China, in the northwest of the country....
to form a 3,000-km VLBI antenna. A proprietary ground application system is responsible for downlink data reception.
Ouyang Ziyuan
Ouyang Ziyuan
Ouyang Ziyuan is a Chinese cosmochemist, geochemist and space advocate. He is a research professor at the Institute of Geochemistry of the Chinese Academy of Sciences.-Geochemical career:...
, a prominent Chinese geologist
Geologist
A geologist is a scientist who studies the solid and liquid matter that constitutes the Earth as well as the processes and history that has shaped it. Geologists usually engage in studying geology. Geologists, studying more of an applied science than a theoretical one, must approach Geology using...
and cosmochemist, was among the first to advocate the exploitation not only of known lunar reserves of metals such as iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
, but also of lunar helium-3
Helium-3
Helium-3 is a light, non-radioactive isotope of helium with two protons and one neutron. It is rare on Earth, and is sought for use in nuclear fusion research...
, an ideal fuel for future nuclear fusion
Nuclear fusion
Nuclear fusion is the process by which two or more atomic nuclei join together, or "fuse", to form a single heavier nucleus. This is usually accompanied by the release or absorption of large quantities of energy...
power plants. Ziyuan, one of the strongest supporters of the Chinese human lunar exploration program, is currently serving as the chief scientist of the program. Another prominent Chinese scientist, Sun Jiadong
Sun Jiadong
Sun Jiadong , was born in Fuxian, Liaoning Province. He is a Chinese scientist and an expert in carrier rocket and satellite technology...
, was assigned as the general designer, while a younger scientist, Sun Zezhou (孙泽州) was assigned as the deputy general designer. The current leading program manager is Luan Enjie (栾恩杰).
The first spacecraft of the program, the unmanned lunar orbiter Chang'e 1, was successfully launched from Xichang Satellite Launch Center
Xichang Satellite Launch Center
The Xichang Satellite Launch Center also known as Base 27 , is a People’s Republic of China space vehicle launch facility approximately 64 km northwest of Xichang City, Liangshan Yi Autonomous Prefecture in Sichuan Province....
on October 24, 2007, having been delayed from the initial planned date of 17–19 April 2007. A second unmanned orbiter, Chang'e 2
Chang'e 2
Chang'e 2 is a Chinese unmanned lunar probe that was launched on 1 October 2010. It was a follow-up to the Chang'e 1 lunar probe, which was launched in 2007. Chang'e 2 was part of the first phase of the Chinese Lunar Exploration Program, and conducted research from a 100-kilometer-high lunar orbit...
, was launched successfully on October 1, 2010. Chang'e 3
Chang'e 3
Chang'e 3 is a Chinese lunar exploration mission, incorporating a robotic lander and rover. Scheduled for launch in 2013 as part of the second phase of the Chinese Lunar Exploration Program, it will be China's first lunar rover, and the first spacecraft to make a soft landing on the Moon since the...
, China's first lunar rover, is expected to launch in 2013. A manned expedition may occur in 2025-2030.
Program structure
According to CNSACNSA
CNSA may refer to:* China National Space Administration* China National School of Administration* Canadian Nursing Students' Association* California Nursing Student Association...
, the program will be divided into three main operational phases:
Phase I : Orbital mission (Chang'e 1 & 2)
The first phase of the exploration program entailed the launch of two lunar orbiters, and is now effectively complete.- Chang'e 1 was successfully launched on October 24, 2007.
- Chang'e 2Chang'e 2Chang'e 2 is a Chinese unmanned lunar probe that was launched on 1 October 2010. It was a follow-up to the Chang'e 1 lunar probe, which was launched in 2007. Chang'e 2 was part of the first phase of the Chinese Lunar Exploration Program, and conducted research from a 100-kilometer-high lunar orbit...
was successfully launched on October 1, 2010.
Phase II : Soft lander (Chang'e 3 & 4)
In the second phase of the lunar exploration program, two lunar landers will be launched to deploy Moon rovers for surface exploration in a limited area. These missions were originally planned for 2012, requiring the use of the CZ-5/E heavy launch vehicle.Currently, the second and third phases of the program will both require the availability of the heavy-lift Long March 5 (CZ-5)
Long March 5 rocket family
Long March 5 is a Chinese next-generation heavy lift launch system that is currently under development by China Academy of Launch Vehicle Technology . Currently, six CZ-5 vehicle configurations are planned for different missions, with a maximum payload capacity of 25,000 kg to LEO and...
booster. Huang Chunping, the former head of rocket science for China's manned space program, told Xinhua news agency in March 2007 that the Long March 5 (CZ-5) rocket would be ready for launch 'in seven or eight years', which implied that CZ-5 would not be used in the second phase of the Chang'e program. The Hainan Spaceport
Wenchang Satellite Launch Center
Wenchang Satellite Launch Center , located near Wenchang on the north-east coast of Hainan Island, is a former sub-orbital test center currently under upgrade. It is the fourth and southernmost space vehicle launch facility of the People's Republic of China...
, China's fourth and southernmost space center, will be upgraded to suit the new CZ-5 Heavy ELV
ELV
ELV or ELVs may refer to:*Elfin Cove Seaplane Base, an airport in Alaska that has IATA code ELV*End of Life Vehicles Directive, a European Union directive to facilitate recycling and reuse of old automobiles...
. It has, however, been reported that the second phase might use a CZ-3B
Long March rocket
A Long March rocket or Chang Zheng rocket as in Chinese pinyin is any rocket in a family of expendable launch systems operated by the People's Republic of China. Development and design falls under the auspices of the China Academy of Launch Vehicle Technology...
rocket instead.
It has been reported that the second phase of the program would include the launch of at least two landers, carrying small remote-controlled rovers to conduct an inspection of the Moon's surface and probe its resources. The rovers would also provide data to determine the selection of a site for a manned Moon base.
On December 14, 2005, many aspects of the above information were confirmed, when it was reported that "an effort to launch lunar orbiting satellites will be supplanted in 2007 by a program aimed at accomplishing an unmanned lunar landing. A program to return unmanned space vehicles from the Moon will begin in 2012 and last for five years, until the manned program gets underway" in 2017.
A six-wheeled lunar vehicle has been under development since 2002 at the Shanghai Aerospace System Engineering Institute, where a specialized testing laboratory has been outfitted to replicate the lunar surface. The 1.5-meter high, 200-kilogram rover is designed to transmit video in real time, dig into the lunar surface and analyze soil samples. With an average speed of 100 meters/hour, it can negotiate inclines and has automatic sensors to prevent it from crashing into other objects.
In late 2008, Chen Qiufa, the Deputy Minister of the MIIT and head of SASTIND, indicated that the Chang’e 3 Lunar Rover would launch in late 2011 on a Long March 3B
Long March 3B
The Long March 3B , also known as the Chang Zheng 3B, CZ-3B and LM-3B, is a Chinese orbital carrier rocket. Introduced in 1996, it is launched from Launch Area 2 at the Xichang Satellite Launch Centre...
rocket. The rover will conduct studies of the Moon’s geology, topography, and mineral and chemical composition.
In 2009, the 2013 launch date was confirmed for a landing craft and rover called Chang'e-3. The lander will use variable thrusters to make a vertical landing on the surface near the Moon's equatorial region. The lunar rover will leave Chang'e-3 and work on the surface for three months. Energy will be provided by radioisotope thermoelectric generator
Radioisotope thermoelectric generator
A radioisotope thermoelectric generator is an electrical generator that obtains its power from radioactive decay. In such a device, the heat released by the decay of a suitable radioactive material is converted into electricity by the Seebeck effect using an array of thermocouples.RTGs can be...
, so that the rover can operate through lunar nights.
Phase III : Automated sample return (Chang'e 5)
The third phase of the lunar exploration program is planned for 2017, entailing the use of the CZ-5/E heavy launch vehicle.On the basis of the lander mission, a lunar sample return mission will be undertaken, with up to two kilograms of lunar samples being returned to Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
.
Orbit design and flight sequence control
Given the conditions of the three-body system of the EarthEarth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
, the Moon and a lunar satellite
Satellite
In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavour. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon....
, the orbit design of lunar exploration satellites is more complicated than that of Earth-orbiting satellites, which only deal with a two-body system. The Chang'e 1 and Chang'e 2
Chang'e 2
Chang'e 2 is a Chinese unmanned lunar probe that was launched on 1 October 2010. It was a follow-up to the Chang'e 1 lunar probe, which was launched in 2007. Chang'e 2 was part of the first phase of the Chinese Lunar Exploration Program, and conducted research from a 100-kilometer-high lunar orbit...
lunar satellites were sent into the highly elliptical Earth orbits; after separating from their launch vehicles, they entered an Earth-Moon transfer orbit through three accelerations in the phase-modulated orbit. These accelerations were conducted 16, 24, and 48 hours into the mission by each satellite's own propulsion system, during which several orbit adjustments and attitude maneuvers were carried out so as to ensure the satellites' capture by lunar gravity. After operating in the Earth-Moon orbit for 4–5 days, each satellite entered a lunar acquisition orbit. Having entered their target orbits, Chang'e 1 and Chang'e 2 carried out their pre-designed missions after conducting three brakings and experiencing three different orbit phases.
The three-vector control problem of attitude control
During lunar orbit, the satellites always had to be oriented towards the Earth, the Moon and the SunSun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
. All onboard detectors had to be kept facing the lunar surface to complete their scientific exploration missions, while the transmitting/receiving antennas had to be facing the Earth to receive commands and transfer scientific data. Each satellite's solar panels, meanwhile, had to be oriented towards the Sun to acquire power for normal operation. During lunar orbit, the three bodies of the Earth, the Moon and the Sun rotate relatively, so attitude control was a complex three-vector control process, with the Chang'e satellites having to adjust their attitude carefully to maintain an optimal angle towards all three bodies.
Satellite environmental adaptability
The complexity of the space environmentSpace environment
Space environment is a branch of astronautics, aerospace engineering and space physics that seeks to understand and address conditions existing in space that affect the operation of spacecraft...
encountered during the Chang'e missions led to higher requirements for environmental adaptability and reliability for the satellites and their instruments. The high-radiation environment in Earth-Moon space required hardened electronic
Radiation hardening
Radiation hardening is a method of designing and testing electronic components and systems to make them resistant to damage or malfunctions caused by ionizing radiation , such as would be encountered in outer space, high-altitude flight, around nuclear reactors, particle accelerators, or during...
s to prevent electromagnetic damage to satellite instruments. Additionally, the great degree of temperature range - from 130℃ on the side of the satellite facing the sun to -170℃ on the side facing away from the sun - imposed strict requirements for temperature control in the design of the detectors.
Long-range TT&C and communication
The biggest challenge in Phase I of the Lunar Exploration Program was the operation of the Telemetry, Tracking and Command (TT&C) system, because its transmission capability had to have sufficient range to contact spacecraft in lunar orbit. China's standard satellite telemetry had a range of as much as 80,000 km, but the distance between the Moon and the Earth can exceed 400,000 km when the Moon is at apogee. In addition, the Chang'e satellites had to carry out many attitude maneuvers during their flights to the Moon and during operations in lunar orbit. The distance across China from east to west is only 5,000 km, forming another challenge to TT&C continuity. At present, the combination of a basic TT&C system and the Chinese astronomical observation network has met the basic needs of the Chang'e program, but only by a small margin.Russian cooperation
Anatoly PerminovAnatoly Perminov
Dr. Prof. Anatoly Nikolayevich Perminov is a Russian rocket scientist and a mechanical engineer. He served as the General Director of Russian Federal Space Agency in 2004–2011.-Career:...
, head of the Russian Federal Space Agency
Russian Federal Space Agency
The Russian Federal Space Agency , commonly called Roscosmos and abbreviated as FKA and RKA , is the government agency responsible for the Russian space science program and general aerospace research. It was previously the Russian Aviation and Space Agency .Headquarters of Roscosmos are located...
, revealed in September 2006 in RIA Novosti that Russia and China were working on lunar exploration as partners, and that the Russian-Chinese Space Sub-Commission's priority was to conclude a joint lunar exploration agreement by the end of that year.
See also
- MoonMoonThe Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
- Chinese space programChinese space programThe space program of the People's Republic of China is directed by the China National Space Administration . Its technological roots can be traced back to the late 1950s, when the People's Republic began a rudimentary ballistic missile program in response to perceived American threats...
- Exploration of the MoonExploration of the MoonThe physical exploration of the Moon began when Luna 2, a space probe launched by the Soviet Union, made an impact on the surface of the Moon on September 14, 1959. Prior to that the only available means of exploration had been observation. The invention of the optical telescope brought about the...
- Robotic exploration of the MoonRobotic exploration of the Moon-Pioneer program:*Pioneer 0 – failure – orbiter*Pioneer 1 – failure – orbiter*Pioneer 2 – failure – orbiter*Pioneer 3 – failure – flyby...
- List of current and future lunar missions