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Chang'e 2 (; ) is a Chinese
unmanned An uncrewed vehicle or unmanned vehicle is a vehicle without a person on board. Uncrewed vehicles can either be under telerobotic control—remote controlled or remote guided vehicles—or they can be autonomously controlled—autonomous vehicl ...
lunar probe The 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 observatio ...
that was launched on 1 October 2010. It was a follow-up to the
Chang'e 1 Chang'e 1 (; ) was an unmanned Chinese lunar-orbiting spacecraft, part of the first phase of the Chinese Lunar Exploration Program. The spacecraft was named after the Chinese Moon goddess, Chang'e. Chang'e 1 was launched on 24 October 2007 at 1 ...
lunar probe, which was launched in 2007. Chang'e 2 was part of the first phase of the
Chinese Lunar Exploration Program The Chinese Lunar Exploration Program (CLEP; ), also known as the Chang'e Project () after the Chinese moon goddess Chang'e, is an ongoing series of robotic Moon missions by the China National Space Administration (CNSA). The program incorpor ...
, and conducted research from a 100-km-high lunar orbit in preparation for the December 2013 soft landing by the
Chang'e 3 Chang'e 3 (; ) is a robotic lunar exploration mission operated by the China National Space Administration (CNSA), incorporating a robotic lander and China's first lunar rover. It was launched in December 2013 as part of the second phase of t ...
lander and rover. Chang'e 2 was similar in design to Chang'e 1, although it featured some technical improvements, including a more advanced onboard camera. Like its predecessor, the probe was named after
Chang'e Chang'e ( ; , alternatively rendered as Chang-Er or Ch‘ang-o), originally known as Heng'e, is the Chinese goddess of the Moon. She is the subject of several legends in Chinese mythology, most of which incorporate several of the following elem ...
, an ancient Chinese
moon goddess A lunar deity or moon deity is a deity who represents the Moon, or an aspect of it. These deities can have a variety of functions and traditions depending upon the culture, but they are often related. Lunar deities and Moon worship can be found ...
. After completing its primary objective, the probe left lunar orbit for the Earth–Sun
Lagrangian point In celestial mechanics, the Lagrange points (; also Lagrangian points or libration points) are points of equilibrium for small-mass objects under the influence of two massive orbiting bodies. Mathematically, this involves the solution of th ...
, to test the Chinese tracking and control network, making the
China National Space Administration China National Space Administration (CNSA; ) is the government agency of the People's Republic of China that is responsible for civil space administration and international space cooperation, including organizing or leading foreign exchanges ...
the third space agency after NASA and ESA to have visited this point. It entered orbit around L2 on 25 August 2011, and began transmitting data from its new position in September 2011."Chinese space craft travels 1.7 mn km deep into space"
''
India Times ''The Times of India'', also known by its abbreviation ''TOI'', is an Indian English-language daily newspaper and digital news media owned and managed by The Times Group. It is the third-largest newspaper in India by circulation and largest se ...
''. 21 September 2011. Retrieved 17 October 2011.
"Chang'e 2 reaches liberation point 2"
Xinhua Xinhua News Agency (English pronunciation: )J. C. Wells: Longman Pronunciation Dictionary, 3rd ed., for both British and American English, or New China News Agency, is the official state news agency of the People's Republic of China. Xinhua ...
. 27 August 2011. Retrieved 21 November 2011.
In April 2012, Chang'e 2 departed L2 to begin an extended mission to the asteroid 4179 Toutatis, which it successfully flew by in December 2012. This success made China's
CNSA China National Space Administration (CNSA; ) is the government agency of the People's Republic of China that is responsible for civil space administration and international space cooperation, including organizing or leading foreign exchanges ...
the fourth space agency to directly explore asteroids, after
NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding t ...
,
ESA , owners = , headquarters = Paris, Île-de-France, France , coordinates = , spaceport = Guiana Space Centre , seal = File:ESA emblem seal.png , seal_size = 130px , image = Views in the Main Control Room (120 ...
and
JAXA The is the Japanese national air and space agency. Through the merger of three previously independent organizations, JAXA was formed on 1 October 2003. JAXA is responsible for research, technology development and launch of satellites into orb ...
. As of 2014, Chang'e 2 has travelled over 100 million km from Earth, conducting a long-term mission to verify China's deep-space tracking and control systems. Contact with the spacecraft was lost in 2014 as its signal strength weakened due to distance. The probe is expected to return to Earth's vicinity sometime around 2027.


Overview

The
Chinese Lunar Exploration Program The Chinese Lunar Exploration Program (CLEP; ), also known as the Chang'e Project () after the Chinese moon goddess Chang'e, is an ongoing series of robotic Moon missions by the China National Space Administration (CNSA). The program incorpor ...
is designed to be conducted in four Chang'e 4 press conference
CNSA, broadcast on 14 January 2019.
phases of incremental technological advancement: The first is simply reaching lunar orbit, a task completed by Chang'e 1 in 2007 and Chang'e 2 in 2010. The second is landing and roving on the Moon, as
Chang'e 3 Chang'e 3 (; ) is a robotic lunar exploration mission operated by the China National Space Administration (CNSA), incorporating a robotic lander and China's first lunar rover. It was launched in December 2013 as part of the second phase of t ...
did in 2013 and
Chang'e 4 Chang'e 4 (; ) is a robotic spacecraft mission, part of the second phase of the Chinese Lunar Exploration Program. China achieved humanity's first soft landing on the far side of the Moon, on 3 January 2019. A communication relay satellit ...
did in 2019. The third is collecting lunar samples from the near-side and sending them to Earth, a task
Chang'e 5 Chang'e 5 () was the fifth lunar exploration mission of the Chinese Lunar Exploration Program, and China's first lunar sample-return mission. Like its predecessors, the spacecraft is named after the Chinese moon goddess Chang'e. It launched ...
completed in 2020 and
Chang'e 6 Chang'e 6 () is a planned robotic Chinese lunar exploration mission that is expected to launch in 2025 and perform China's second sample return mission. Like its predecessors, the spacecraft is named after the Chinese moon goddess Chang'e. Ov ...
will repeat. The fourth phase consists of development of a robotic research station near the Moon's south pole.China's Planning for Deep Space Exploration and Lunar Exploration before 2030
(PDF) XU Lin, ZOU Yongliao, JIA Yingzhuo. ''Space Sci''., 2018, 38(5): 591-592.
The program aims to facilitate a crewed lunar landing in the 2030s and possibly build an outpost near the south pole.


Design

Chang'e 2 was the backup of the Chang'e 1 probe and it had been modified for its own mission. While Chang'e 1 operated in a 200-km orbit, Chang'e 2 flew at only 100 km, allowing for higher-resolution images and more precise science data. The probe also possessed a higher-resolution camera, being able to resolve features as small as across from orbit. According to Qian Huang of the
Shanghai Astronomical Observatory Shanghai Astronomical Observatory (SHAO), is an astronomical observatory in Shanghai. It has a long history of astrometry, and also operates the Sheshan radio telescope as part of the Chinese VLBI array and the European VLBI Network (EVN). ...
and Yong-Chun Zheng of the NAOC, the spacecraft also had a shorter Earth-to-Moon cruise time of 5 days, rather than 12. The probe's launch rocket had two more boosters to accomplish this more direct route to the Moon. Furthermore, its
laser altimeter A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word "laser" is an acronym for "light amplification by stimulated emission of radiation". The fir ...
's footprint was smaller than Chang'e 1's, achieving 5-meter vertical accuracy in its estimate of the Moon's radius. It also pulsed more frequently – five times per second rather than just once per second, as Chang'e 1's altimeter did. Additionally, the probe's main camera had a spatial resolution of , rather than . The total cost of the Chang'e 2 mission was approximately
CN¥ The renminbi (; symbol: ¥; ISO code: CNY; abbreviation: RMB) is the official currency of the People's Republic of China and one of the world's most traded currencies, ranking as the fifth most traded currency in the world as of April 2022. ...
900 million ($125 million). Late in the mission, Chang'e 2's orbit was lowered to an elliptical one, with the same
apolune An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any ellip ...
(100 km) as Chang'e 1, but with a
perilune An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any ellip ...
of only 15 km. Tracking for the mission was performed with an
X-band The X band is the designation for a band of frequencies in the microwave radio region of the electromagnetic spectrum. In some cases, such as in communication engineering, the frequency range of the X band is rather indefinitely set at approxim ...
radio capability, which was not available for Chang'e 1. Zheng remarked that "the mission goals of Chang'e 2 were focused into the high resolution image for the future landing site of CE-3 lunar lander and rover. The success of Chang'e 2 provided an important technical basis for the successful implementation of China's future lunar exploration," and the ''Queqiao'' relay satellite was based on Chang'e 2 design.


Mission summary


Launch

Chang'e 2 was launched on 1 October 2010 at 10:59:57 UTC aboard a
Long March 3C The Long March 3C (), also known as the Changzheng 3C, CZ-3C and LM-3C, is a Chinese orbital launch vehicle. It is launched from Launch Complex 2 and 3 at the Xichang Satellite Launch Center (XSLC). A three-stage rocket with two strapon liquid ...
rocket from
Xichang Satellite Launch Center The Xichang Satellite Launch Center (XSLC), also known as the Xichang Space Center, is a spaceport of China. It is located in Zeyuan Town (), approximately northwest of Xichang, Liangshan Yi Autonomous Prefecture in Sichuan. The facility bec ...
in
Xichang Xichang, formerly known as Jiandu, Jianchang and Ningyuan(fu), is a city in and the seat of the Liangshan Yi Autonomous Prefecture, in the south of Sichuan, China. In 2012 it had a population of 481,796. History The Qiongdu were the local peo ...
,
Sichuan Sichuan (; zh, c=, labels=no, ; zh, p=Sìchuān; alternatively romanized as Szechuan or Szechwan; formerly also referred to as "West China" or "Western China" by Protestant missions) is a province in Southwest China occupying most of the ...
. The launch of the probe coincided with China's National Day on 1 October, in a symbolic celebration of the country's 61st communist anniversary.


Lunar mission

The spacecraft entered an orbit with a perigee of 200 km and an apogee of 380,000 km, and separated from the carrier rocket as planned. It was the first time that a Chinese lunar probe directly entered an Earth-to-Moon transfer orbit without orbiting the Earth first. After the launch, Chang'e 2 arrived in its lunar orbit within 4 days and 16 hours. Later, the probe lowered its orbit to , with a perilune of . Chang'e 2 entered its 100 km working orbit on 9 October 2010 after three successful brakings. On 8 November 2010, the Chinese government announced the success of all of Chang'e 2's mission objectives, and published lunar surface images with a resolution of up to . In February 2012, the Chinese government released a complete lunar map constructed from Chang'e 2's data, claiming that it was the highest-resolution map of the entire Moon yet recorded. The full dataset, including the map with resolutions of 7, 20 and 50 m, and elevations model with resolutions of 20 and 50 m, is available for free download since April 2018.


L2 mission

On 8 June 2011, Chang'e 2 completed its extended mission, and left lunar orbit for the Earth–Sun L2
Lagrangian point In celestial mechanics, the Lagrange points (; also Lagrangian points or libration points) are points of equilibrium for small-mass objects under the influence of two massive orbiting bodies. Mathematically, this involves the solution of th ...
, to test the Chinese tracking and control network. The probe reached L2 on 25 August 2011 at 23:27 Beijing time (14:27 UTC) after a 77-day cruise, becoming the first object ever to reach the L2 point directly from lunar orbit, and travelling further than any previous Chinese space probe. The probe beamed its first batch of data from L2 in September 2011. Though it was expected to remain at L2 until the end of 2012, it departed on an extended mission in April 2012.


4179 Toutatis mission

According to
Ouyang Ziyuan Ouyang Ziyuan (, born 9 October 1935) is a Chinese cosmochemist, geochemist and space advocate. He is a research professor at the Institute of Geochemistry of the Chinese Academy of Sciences. Asteroid 8919 Ouyangziyuan, discovered in 1996, was ...
's report to the 16th Conference of the
Chinese Academy of Sciences The Chinese Academy of Sciences (CAS); ), known by Academia Sinica in English until the 1980s, is the national academy of the People's Republic of China for natural sciences. It has historical origins in the Academia Sinica during the Republ ...
, Chang'e 2 departed from L2 on 15 April 2012, and began a mission to the asteroid 4179 Toutatis. The flyby was successfully achieved on 13 December 2012 at 16:30:09 Beijing Time (08:30:09 GMT). Close-up images of the asteroid, with a resolution of up to per pixel, were later published online. The flyby was the first time an unmanned spacecraft had imaged the asteroid so closely. Chang'e-2 came as close as to Toutatis, and took pictures of the asteroid at a relative velocity of per second."China's space probe flies by asteroid Toutatis"
. China Daily. 16 December 2012. Retrieved 13 February 2015.
China thus became the fourth space agency to conduct a successful mission to an asteroid, after
NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding t ...
,
ESA , owners = , headquarters = Paris, Île-de-France, France , coordinates = , spaceport = Guiana Space Centre , seal = File:ESA emblem seal.png , seal_size = 130px , image = Views in the Main Control Room (120 ...
and
JAXA The is the Japanese national air and space agency. Through the merger of three previously independent organizations, JAXA was formed on 1 October 2003. JAXA is responsible for research, technology development and launch of satellites into orb ...
.


Deep-space journey

As of 2016, Chang'e 2 has reached a distance of over 200 million km from Earth; potentially, it has enough fuel remaining to continue functioning up to a distance of 300 million km, according to the China Aerospace Corporation. Contact with the probe was lost in 2014, however, due to weakening signal strength. It is estimated that Chang'e 2 will return to the Earth's vicinity around 2027.


See also

*
Chinese Lunar Exploration Program The Chinese Lunar Exploration Program (CLEP; ), also known as the Chang'e Project () after the Chinese moon goddess Chang'e, is an ongoing series of robotic Moon missions by the China National Space Administration (CNSA). The program incorpor ...
**
Chang'e 1 Chang'e 1 (; ) was an unmanned Chinese lunar-orbiting spacecraft, part of the first phase of the Chinese Lunar Exploration Program. The spacecraft was named after the Chinese Moon goddess, Chang'e. Chang'e 1 was launched on 24 October 2007 at 1 ...
**
Chang'e 3 Chang'e 3 (; ) is a robotic lunar exploration mission operated by the China National Space Administration (CNSA), incorporating a robotic lander and China's first lunar rover. It was launched in December 2013 as part of the second phase of t ...
/ Yutu rover **
Chang'e 4 Chang'e 4 (; ) is a robotic spacecraft mission, part of the second phase of the Chinese Lunar Exploration Program. China achieved humanity's first soft landing on the far side of the Moon, on 3 January 2019. A communication relay satellit ...
/
Yutu-2 ''Yutu-2'' is the robotic lunar rover component of CNSA's Chang'e 4 mission to the Moon, launched on 7 December 2018 18:23 UTC, it entered lunar orbit on 12 December 2018 before making the first soft landing on the far side of the Moon on 3 J ...
**
Chang'e 5-T1 Chang'e 5-T1 () was an experimental robotic spacecraft that was launched to the Moon on 23 October 2014 by the China National Space Administration (CNSA) to conduct atmospheric re-entry tests on the capsule design planned to be used in the Cha ...
**
Chang'e 5 Chang'e 5 () was the fifth lunar exploration mission of the Chinese Lunar Exploration Program, and China's first lunar sample-return mission. Like its predecessors, the spacecraft is named after the Chinese moon goddess Chang'e. It launched ...
* List of asteroids visited by spacecraft *
Robotic exploration of the Moon The 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 observatio ...


References


External links


Lunar mission timeline
NASA.
Recent Lunar missions
NASA.

IanRidpath.com. * ttp://www.planetary.org/blogs/emily-lakdawalla/2010/2774.html "Five amazing engineering camera videos from Chang'E 2"(includes lunar imagery, thruster firings, and solar panel deployment).
Planetary Society The Planetary Society is an American internationally-active non-governmental nonprofit organization. It is involved in research, public outreach, and political space advocacy for engineering projects related to astronomy, planetary science, a ...
. {{DEFAULTSORT:Chang'e 2 Space probes launched in 2010 2010 in China Chinese Lunar Exploration Program Missions to the Moon Chinese space probes Spacecraft that orbited the Moon Missions to asteroids Spacecraft using Lissajous orbits Derelict space probes Spacecraft launched by Long March rockets