Chang'e 4

Chang'e 4 (/tʃɑːŋˈə/; Chinese: 嫦娥四号; pinyin: Cháng'é Sìhào; lit. 'Chang'e No. 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.[12][13]

Chang'e 4
Chang'e 4 lander
Mission typeLander, lunar rover
OperatorCNSA
COSPAR ID2018-103A
SATCAT no.43845
Mission durationLander: 12 months (planned)
Current: 769 days
Rover: 3 months (planned)[1]
Current: 769 days
Spacecraft properties
Launch massLander: 3,640 kg[2]
Rover: 140 kg[2]
Landing massTotal: ~1,200 kg; rover: 140 kg
DimensionsRover: 1.5 × 1.0 × 1.0 m[3]
Start of mission
Launch dateQueqiao relay satellite: 20 May 2018
Lander and rover: 7 December 2018, 18:23 UTC[4]
RocketLong March 3B[5][6]
Launch siteXichang Satellite Launch Center
Earth-Moon L2 point orbiter
Orbital insertion14 June 2018[7]
Lunar lander
Landing dateLander and rover: 3 January 2019, 02:26 UTC[8]
Landing siteVon Kármán crater[9] in the South Pole-Aitken Basin[10]
Lunar rover
Distance covered490.9 m (1,611 ft)
as of 27 July 2020[11]
 

A communication relay satellite, Queqiao, was first launched to a halo orbit near the Earth–Moon L2 point in May 2018. The robotic lander and Yutu-2 (Chinese: 玉兔二号; pinyin: Yùtù Èrhào; lit. 'Jade Rabbit No. 2') rover[14] were launched on 7 December 2018 and entered lunar orbit on 12 December 2018, before landing on the Moon's far side. The mission is the follow-up to Chang'e 3, the first Chinese landing on the Moon.

The spacecraft was originally built as a backup for Chang'e 3 and became available after Chang'e 3 landed successfully in 2013. The configuration of Chang'e 4 was adjusted to meet new scientific and performance objectives.[15] Like its predecessors, the mission is named after Chang'e, the Chinese Moon goddess.

The far side of the Moon, which is not visible from Earth due to tidal locking. The landing site in Von Kármán crater is at bottom center.

Overview

The Chinese Lunar Exploration Program is designed to be conducted in four[16] 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 did in 2013 and Chang'e 4 did in 2019. The third is collecting lunar samples from the near-side and sending them to Earth, a task for the future Chang'e 5 and Chang'e 6 missions. The fourth phase consists of development of a robotic research station near the Moon's south pole.[16][17][18] The program aims to facilitate a crewed lunar landing in the 2030s and possibly the building of an outpost near the south pole.[19][20] The Chinese Lunar Exploration Program has started to incorporate private investment from individuals and enterprises for the first time, a move aimed at accelerating aerospace innovation, cutting production costs, and promoting military–civilian relationships.[21]

This mission will attempt to determine the age and composition of an unexplored region of the Moon, as well as develop technologies required for the later stages of the program.[22]

Launch

The Chang'e 4 mission was first scheduled for launch in 2015 as part of the second phase of the Chinese Lunar Exploration Program.[23][24] But the adjusted objectives and design of the mission imposed delays, and finally launched on 7 December 2018, 18:23 UTC.[4][25]

Selenocentric phase

The spacecraft entered lunar orbit on 12 December 2018, 08:45 UTC.[26] The orbit's perilune was lowered to 15 km (9.3 mi) on 30 December 2018, 00:55 UTC.[27]

Landing took place on 3 January 2019 at 02:26 UTC,[13] shortly after lunar sunrise over the Von Kármán crater in the large South Pole-Aitken basin.[28]

Objectives

An ancient collision event on the Moon left behind a very large crater, called the Aitken Basin, that is now about 13 km (8.1 mi) deep, and it is thought that the massive impactor likely exposed the deep lunar crust, and probably the mantle materials. If Chang'e 4 can find and study some of this material, it would get an unprecedented view into the Moon's internal structure and origins.[1] The specific scientific objectives are:[29]

  • Measure the chemical compositions of lunar rocks and soils
  • Measure lunar surface temperature over the duration of the mission.
  • Carry out low-frequency radio astronomical observation and research using a radio telescope
  • Study of cosmic rays
  • Observe the solar corona, investigate its radiation characteristics and mechanism, and to explore the evolution and transport of coronal mass ejections (CME) between the Sun and Earth.

Components

Queqiao relay satellite
Communication with Chang'e-4 on the Moon's far side
Earth-Moon Lagrangian points: A satellite in a halo orbit around L2, which is behind the Moon, will have a view of both the Earth and the Moon's far side

Direct communication with Earth is impossible on the far side of the Moon, since transmissions are blocked by the Moon. Communications must go through a communications relay satellite, which is placed at a location that has a clear view of both the landing site and the Earth. As part of the Lunar Exploration Program, the China National Space Administration (CNSA) launched the Queqiao (Chinese: 鹊桥; pinyin: Quèqiáo; lit. 'Magpie Bridge') relay satellite on 20 May 2018 to a halo orbit around the Earth–Moon L2 point.[30][31][32] The relay satellite is based on the Chang'e 2 design,[33] has a mass of 425 kg (937 lb), and it uses a 4.2 m (14 ft) antenna to receive X band signals from the lander and rover, and relay them to Earth control on the S band.[34]

The spacecraft took 24 days to reach L2, using a lunar swing-by to save fuel.[7] On 14 June 2018, Queqiao finished its final adjustment burn and entered the L2 halo mission orbit, which is about 65,000 kilometres (40,000 mi) from the Moon. This is the first lunar relay satellite at this location.[7]

The name Queqiao ("Magpie Bridge") was inspired by and came from the Chinese tale The Cowherd and the Weaver Girl.[30]

Longjiang microsatellites

As part of the Chang'e 4 mission, two microsatellites (45 kg or 99 lb each) named Longjiang-1 and Longjiang-2 (Chinese: 龙江; pinyin: Lóng Jiāng; lit. 'Dragon River';[35] also known as Discovering the Sky at Longest Wavelengths Pathfinder or DSLWP [36]), were launched along with Queqiao in May 2018. Both satellites were developed by Harbin Institute of Technology, China.[37] Longjiang-1 failed to enter lunar orbit,[7] but Longjiang-2 succeeded and operated in lunar orbit until 31 July 2019.[38] Longjiang 2's crash site is located at 16.6956°N 159.5170°E / 16.6956; 159.5170 (Longjiang-2 impact site) inside Van Gent crater, where it made a 4 by 5 metre crater upon impact.[39] These microsatellites were tasked to observe the sky at very low frequencies (1–30 megahertz), corresponding to wavelengths of 300 to 10 metres (984 to 33 ft), with the aim of studying energetic phenomena from celestial sources.[32][40][41] Due to the Earth's ionosphere, no observations in this frequency range have been done in Earth orbit,[41] offering potential breakthrough science.[22]

Chang'e lander and Yutu-2 rover

Main article: Yutu-2

As is the case with many of China's space missions, the details of the spacecraft and the mission have been limited.[42] What is known is that much of the Chang'e 4 lander and rover design is modeled after Chang'e-3 and its Yutu rover.[42] In fact, Chang'e 4 was built as a backup to Chang'e 3,[43] and based on the experience and results from that mission, Chang'e 4 was adapted to the specifics of the new mission.[44] The lander and rover were launched by Long March 3B rocket on 7 December 2018, 18:23 UTC, six months after the launch of the Queqiao relay satellite.[4]

The total landing mass is 1,200 kg (2,600 lb).[2] Both the stationary lander and Yutu-2 rover are equipped with a radioisotope heater unit (RHU) in order to heat their subsystems during the long lunar nights,[45] while electrical power is generated by solar panels.

After landing, the lander extended a ramp to deploy the Yutu-2 rover (literally: "Jade Rabbit") to the lunar surface.[7] The rover measures 1.5 × 1.0 × 1.0 m (4.9 × 3.3 × 3.3 ft) and has a mass of 140 kg (310 lb).[2][3] Yutu-2 rover was manufactured in Dongguan, Guangdong province; it is solar-powered, RHU-heated,[45] and it is propelled by six wheels. The rover's nominal operating time is three months,[1] but after the experience with Yutu rover in 2013, the rover design was improved and Chinese engineers are hopeful it will operate for "a few years."[46] In December 2019, Yutu 2 broke the lunar longevity record, previously held by the Soviet Union's Lunokhod 1 rover.[47]

Science payloads
View of landing site, marked by two small arrows, taken by the Lunar Reconnaissance Orbiter on 30 January 2019[48]

The communications relay satellite, orbiting microsatellite, lander and rover each carry scientific payloads. The relay satellite is performing radio astronomy,[49] whereas the lander and Yutu-2 rover will study the geophysics of the landing zone.[9][50] The science payloads are, in part, supplied by international partners in Sweden, Germany, the Netherlands, and Saudi Arabia.[51]

Relay satellite

The primary function of the Queqiao relay satellite that is deployed in a halo orbit around the Earth–Moon L2 point is to provide continuous relay communications between Earth and the lander on the far side of the Moon.[32][49]

The Queqiao launched on 21 May 2018. It used lunar swing-by transfer orbit to reach moon. After the first trajectory correction maneuvers (TCMs), the spacecraft is in place. On 25 May, Queqiao approached the vicinity of the L2. After several small adjustments, Queqiao arrived at L2 halo orbit on 14 June.[52][53]

Additionally, this satellite hosts the Netherlands–China Low-Frequency Explorer (NCLE), an instrument performing astrophysical studies in the unexplored radio regime of 80 kilohertz to 80 megahertz.[54][55] It was developed by the Radboud University in Netherlands and the Chinese Academy of Sciences. The NCLE on the orbiter and the LFS on the lander work in synergy performing low-frequency (0.1–80 MHz) radio astronomical observations.[40]

Lunar lander
Chang'e 4 – Lander (left arrow) and Rover (right arrow) on the Moon surface (NASA photo, 8 February 2019).[56]
Chang'e 4 lander (center) and rover (west-northwest of lander) 6 months after landing.

The lander and rover carry scientific payloads to study the geophysics of the landing zone, with a life science and modest chemical analysis capability.[9][50][40] The lander is equipped with the following payloads:

  • Landing Camera (LCAM), mounted on the bottom of the spacecraft, the camera began to produce a video stream at the height of 12 km (7.5 mi) above the lunar surface.
  • Terrain Camera (TCAM), mounted on top of the lander and able to rotate 360°, is being used to image the lunar surface and the rover in high definition.
  • Low Frequency Spectrometer (LFS)[40] to research solar radio bursts at frequencies between 0.1–40 MHz and to study the lunar ionosphere.
  • Lunar Lander Neutrons and Dosimetry (LND), a (neutron) dosimeter developed by Kiel University in Germany.[57] It is gathering information about radiation dosimetry for future human exploration of the Moon, and will contribute to solar wind studies.[58][59] It has shown that the radiation dose on the surface of the Moon is 2 to 3 times higher than what astronauts experience in the ISS.[60][61]
  • Lunar Micro Ecosystem,[62] is a 3 kg (6.6 lb) sealed biosphere cylinder 18 cm (7.1 in) long and 16 cm (6.3 in) in diameter with seeds and insect eggs to test whether plants and insects could hatch and grow together in synergy.[54] The experiment includes six types of organisms:[63][64] cottonseed, potato, rapeseed, Arabidopsis thaliana (a flowering plant), as well as yeast and fruit fly[65] eggs. Environmental systems keep the container hospitable and Earth-like, except for the low lunar gravity and radiation.[66] If the fly eggs hatch, the larvae would produce carbon dioxide, while the germinated plants would release oxygen through photosynthesis. It was hoped that together, the plants and fruit flies could establish a simple synergy within the container. Yeast would play a role in regulating carbon dioxide and oxygen, as well as decomposing processed waste from the flies and the dead plants to create an additional food source for the insects.[63] The biological experiment was designed by 28 Chinese universities.[67] Research in such closed ecological systems informs astrobiology and the development of biological life support systems for long duration missions in space stations or space habitats for eventual space farming.[68][69][70]
Result: Within a few hours after landing on 3 January 2019, the biosphere's temperature was adjusted to 24°C and the seeds were watered. On 15 January 2019, it was reported that cottonseed, rapeseed and potato seeds had sprouted, but images of only cottonseed were released.[63] However, on 16 January, it was reported that the experiment was terminated due to an external temperature drop to −52 °C (−62 °F) as the lunar night set in, and a failure to warm the biosphere close to 24°C.[71] The experiment was terminated after nine days instead of the planned 100 days, but valuable information was obtained.[71][72]

Lunar rover
  • Panoramic Camera (PCAM), is installed on the rover's mast and can rotate 360°. It has a spectral range of 420 nm–700 nm and it acquires 3D images by binocular stereovision.[40]
  • Lunar penetrating radar (LPR), is a ground penetrating radar with a probing depth of approximately 30 m with 30 cm vertical resolution, and more than 100 m with 10 m vertical resolution.[40]
  • Visible and Near-Infrared Imaging Spectrometer (VNIS), for imaging spectroscopy that can then be used for identification of surface materials and atmospheric trace gases. The spectral range covers visible to near-infrared wavelengths (450 nm - 950 nm).
  • Advanced Small Analyzer for Neutrals (ASAN), is an energetic neutral atom analyzer provided by the Swedish Institute of Space Physics (IRF). It will reveal how solar wind interacts with the lunar surface, which may help determine the process behind the formation of lunar water.[57]

Cost

The cost of the entre mission was close to building one kilometer of subway. The cost-per-kilometer of subway in China varies from 500 million yuan (about $72 million USD) to 1.2 billion yuan (about $172 million USD), based on the difficulty of construction. [73]

Landing site

The landing site is within a crater called Von Kármán[9] (180 km or 110 mi diameter) in the South Pole-Aitken Basin on the far side of the Moon that was still unexplored by landers.[10][74] The site has symbolic as well as scientific value. Theodore von Kármán was the PhD advisor of Qian Xuesen, the founder of the Chinese space program.[75]

The landing craft touched down at 02:26 UTC on 3 January 2019, becoming the first spacecraft to land on the far side of the Moon.[76]

The Yutu-2 rover was deployed about 12 hours after the landing.[77]

The selenographic coordinates of the landing site are 177.5991°E, 45.4446°S, at an elevation of -5935 m.[78][79] The landing site was later (February 2019) named Statio Tianhe. Four other lunar features were also named during this mission: a mountain (Mons Tai) and three craters (Zhinyu, Hegu, and Tianjin).[80]

Operations and results

A few days after landing, Yutu-2 went into hibernation for its first lunar night and it resumed activities on 29 January 2019 with all instruments operating nominally. During its first full lunar day, the rover travelled 120 m (390 ft), and on 11 February 2019 it powered down for its second lunar night.[81][82] In May 2019, it was reported that Chang'e 4 has identified what appear to be mantle rocks on the surface, its primary objective.[83][84][85] In January 2020, China released a large amount of data and high-resolution images from the mission lander and rover.[86] In February 2020, Chinese astronomers reported, for the first time, a high-resolution image of a lunar ejecta sequence, and, as well, direct analysis of its internal architecture. These were based on observations made by the Lunar Penetrating Radar (LPR) on board the Yutu-2 rover while studying the far side of the Moon.[87][88]

International collaboration

Chang'e 4 marks the first major US-China collaboration in space exploration since the 2011 Congressional ban. Scientists from both countries had regular contact prior to the landing.[89] This included talks about observing plumes and particles lofted from the lunar surface by the probe's rocket exhaust during the landing to compare the results with theoretical predictions, but NASA's Lunar Reconnaissance Orbiter (LRO) was not in the right position for this during the landing.[90] The US also informed Chinese scientists about its satellites in orbit around the Moon, while China shared with the US scientists the longitude, latitude, and timing of Chang'e 4's landing.[91]

China has agreed to a request from NASA to use the Chang'e 4 probe and Queqiao relay satellite in future US Moon missions.[92]

The first panorama from the far side of the Moon by Chang'e 4 lander, with the Yutu-2 rover

See also

References
  1. China says it will launch 2 robots to the far side of the moon in December on an unprecedented lunar exploration mission Archived 9 December 2018 at the Wayback Machine. Dave Mosher, Business Insider. 16 August 2018.
  2. Chang'e 3, 4 (CE 3, 4) Archived 20 March 2018 at the Wayback Machine. Gunter Dirk Krebs, Gunter's Space Page.
  3. This is the rover China will send to the 'dark side' of the Moon Archived 31 August 2018 at the Wayback Machine. Steven Jiang, CNN News. 16 August 2018.
  4. "探月工程嫦娥四号探测器成功发射 开启人类首次月球背面软着陆探测之旅". China National Space Administration (in Chinese). Archived from the original on 10 December 2018. Retrieved 8 December 2018.
  5. Chang'e-4: Far side of the Moon lander and rover mission to launch in December Archived 18 June 2018 at the Wayback Machine. Global Times, 18 June 2018.
  6. Launch Schedule 2018 Archived 16 August 2018 at the Wayback Machine. SpaceflightNow, 18 September 2018.
  7. Xu, Luyuan (15 June 2018). "How China's lunar relay satellite arrived in its final orbit". The Planetary Society. Archived from the original on 17 October 2018.
  8. Barbosa, Rui (3 January 2019). "China lands Chang'e-4 mission on the far side of the Moon". Nasaspacefight. Archived from the original on 3 January 2019. Retrieved 3 January 2019.
  9. China's Journey to the Lunar Far Side: A Missed Opportunity? Paul D. Spudis, Air & Space Smithsonian. 14 June 2017.
  10. Ye, Peijian; Sun, Zezhou; Zhang, He; Li, Fei (2017). "An overview of the mission and technical characteristics of Change'4 Lunar Probe". Science China Technological Sciences. 60 (5): 658. Bibcode:2017ScChE..60..658Y. doi:10.1007/s11431-016-9034-6. S2CID 126303995.
  11. "China's lunar rover travels over 424 meters on moon's far side". Xinhua. 1 April 2020. Retrieved 7 April 2020.
  12. Lyons, Kate. "Chang'e 4 landing: China probe makes historic touchdown on far side of the moon". The Guardian. Archived from the original on 3 January 2019. Retrieved 3 January 2019.
  13. "China successfully lands Chang'e-4 on far side of Moon". Archived from the original on 3 January 2019. Retrieved 3 January 2019.
  14. Mosherand, Dave; Gal, Shayanne (3 January 2019). "This map shows exactly where China landed its Chang'e-4 spacecraft on the far side of the moon". Business Insider. Archived from the original on 4 January 2019.
  15. Notably, the rover was modified "to meet the demands of the far-side terrain, but also to avoid the fate of the robot's predecessor, which became immobilized after driving only 360 feet (110 meters)" Pearlman, Robert Z. (12 December 2018). "China's Chang'e 4 Moon Lander and Rover to Touch Down As Toys". Future US, Inc. Retrieved 15 November 2019.
  16. Chang'e 4 press conference. CNSA, broadcast on 14 January 2019.
  17. 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. doi:10.11728/cjss2018.05.591
  18. A Tentative Plan of China to Establish a Lunar Research Station in the Next Ten Years. Zou, Yongliao; Xu, Lin; Jia, Yingzhuo. 42nd COSPAR Scientific Assembly. Held 14–22 July 2018, in Pasadena, California, USA, Abstract id. B3.1-34-18.
  19. China lays out its ambitions to colonize the moon and build a "lunar palace" Archived 29 November 2018 at the Wayback Machine. Echo Huang, Quartz. 26 April 2018.
  20. China's moon mission to boldly go a step further Archived 31 December 2017 at the Wayback Machine. Stuart Clark, The Guardian 31 December 2017.
  21. "China Outlines New Rockets, Space Station and Moon Plans". Space. 17 March 2015. Archived from the original on 1 July 2016. Retrieved 27 March 2015.
  22. China's Moon Missions Are Anything But Pointless. Paul D. Spudis, Air & Space Smithsonian. 3 January 2017.
  23. "Ouyang Ziyuan portrayed Chang E project follow-up blueprint". Science Times. 9 December 2011. Archived from the original on 3 February 2012. Retrieved 25 June 2012.
  24. Witze, Alexandra (19 March 2013). "China's Moon rover awake but immobile". Nature. doi:10.1038/nature.2014.14906. S2CID 131617225. Archived from the original on 23 March 2014. Retrieved 25 March 2014.
  25. China launches historic mission to land on far side of the moon Archived 7 December 2018 at the Wayback Machine Stephen Clark, Spaceflight Now. 7 December 2018.
  26. "China's Chang'e-4 probe decelerates near moon". Xinhua. 12 December 2018. Archived from the original on 12 December 2018. Retrieved 12 December 2018.
  27. "China's Chang'e-4 probe changes orbit to prepare for moon-landing". XinhuaNet. 30 December 2018. Archived from the original on 1 January 2019. Retrieved 31 December 2018.
  28. Jones, Andrew (31 December 2018). "How the Chang'e-4 spacecraft will land on the far side of the Moon". GBTIMES. Archived from the original on 2 January 2019. Retrieved 3 January 2019.
  29. To the Far Side of the Moon: China's Lunar Science Goals Archived 10 March 2018 at the Wayback Machine. Leonard David, Space. 9 June 2016.
  30. Wall, Mike (18 May 2018). "China Launching Relay Satellite Toward Moon's Far Side Sunday". Space.com. Archived from the original on 18 May 2018.
  31. Emily Lakdawalla (14 January 2016). "Updates on China's lunar missions". The Planetary Society. Archived from the original on 17 April 2016. Retrieved 24 April 2016.
  32. Jones, Andrew (24 April 2018). "Chang'e-4 lunar far side satellite named 'magpie bridge' from folklore tale of lovers crossing the Milky Way". GBTimes. Archived from the original on 24 April 2018. Retrieved 28 April 2018.
  33. Future Chinese Lunar Missions: Chang'e 4 - Farside Lander and Rover. David R. Williams, NASA Goddard Space Flight Center. 7 December 2018.
  34. Chang'e 4 relay satellite, Queqiao: A bridge between Earth and the mysterious lunar farside Archived 21 May 2018 at the Wayback Machine. Xu, Luyan, The Planetary Society. 19 May 2018. Retrieved on 20 May 2018
  35. Radio Experiment Launches With China's Moon Orbiter. David Dickinson, Sky & Telescope. 21 May 2018.
  36. China Moon Mission: Lunar Microsatellite Problem?. Leonard David, Inside Outer Space. 27 May 2018.
  37. Orbiter Longjiang-2 Smashes into Moon
  38. @planet4589 (31 July 2019). "The Chinese Longjiang-2 (DSLWP-B) lunar orbiting spacecraft completed its mission on Jul 31 at about 1420 UTC, in a planned i[m]pact on the lunar surface" (Tweet). Retrieved 1 August 2019 – via Twitter.
  39. "Longjiang-2 Impact Site Found! | Lunar Reconnaissance Orbiter Camera". lroc.sese.asu.edu. Retrieved 14 November 2019.
  40. The scientific objectives and payloads of Chang'E−4 mission. (PDF) Yingzhuo Jia, Yongliao Zou, Jinsong Ping, Changbin Xue, Jun Yan, Yuanming Ning. Planetary and Space Science. 21 February 2018. doi:10.1016/j.pss.2018.02.011
  41. Jones, Andrew (1 March 2018). "Chang'e-4 lunar far side mission to carry microsatellites for pioneering astronomy". GB Times. Archived from the original on 10 March 2018. Retrieved 1 August 2019.
  42. This weekend, China embarks on a historic mission to land on the far side of the Moon Archived 7 December 2018 at the Wayback Machine. Loren Grush, The Verge. 6 December 2018.
  43. Wang, Qiong; Liu, Jizhong (2016). "A Chang'e-4 mission concept and vision of future Chinese lunar exploration activities". Acta Astronautica. 127: 678–683. Bibcode:2016AcAau.127..678W. doi:10.1016/j.actaastro.2016.06.024.
  44. Pioneering Chang’e-4 lunar far side landing mission to launch in December. Andrew Jones, Space News. 15 August 2018.
  45. China Shoots for the Moon's Far Side. (PDF) IEEE.org. 2018.
  46. China's Chang'e 4 spacecraft to try historic landing on far side of Moon 'between January 1 and 3' Archived 2 January 2019 at the Wayback Machine. South China Morning Post. 31 December 2018.
  47. China's Farside Moon Rover Breaks Lunar Longevity Record. Leonard David, Space.com. 12 December 2019.
  48. Robinson, Mark (6 February 2019). "First Look: Chang'e 4". Arizona State University. Retrieved 8 February 2019.
  49. Chang'e 4 Relay Archived 1 January 2018 at the Wayback Machine. Gunter Drunk Krebs, Gunter's Space Page.
  50. Plans for China's farside Chang'e 4 lander science mission taking shape Archived 23 June 2016 at the Wayback Machine. Emily Lakdawalla, The Planetary Society, 22 June 2016.
  51. Andrew Jones (11 January 2018). "Testing on China's Chang'e-4 lunar far side lander and rover steps up in preparation for launch". GBTimes. Archived from the original on 12 January 2018. Retrieved 12 January 2018.
  52. Jones, Andrew (21 May 2018). "China launches Queqiao relay satellite to support Chang'e 4 lunar far side landing mission". GBTimes. Retrieved 22 May 2018.
  53. Luyuan Xu (15 June 2018). "How China's lunar relay satellite arrived in its final orbit". planetary.org.
  54. David, Leonard. "Comsat Launch Bolsters China's Dreams for Landing on the Moon's Far Side". Scientific American. Archived from the original on 29 November 2018.
  55. "Netherlands–China Low-Frequency Explorer (NCLE)". ASTRON. Archived from the original on 10 April 2018. Retrieved 10 April 2018.
  56. NASA (8 February 2019). "Chang'e 4 Rover comes into view". EurekAlert!. Retrieved 9 February 2019.
  57. Andrew Jones (16 May 2016). "Sweden joins China's historic mission to land on the far side of the Moon in 2018". GBTimes. Archived from the original on 6 October 2018. Retrieved 12 January 2018.
  58. Wimmer-Schweingruber, Robert f. (18 August 2020). "The Lunar Lander Neutron and Dosimetry (LND) Experiment on Chang'E 4". Space Science Reviews. 216: 104.
  59. The Lunar Lander Neutron & Dosimetry (LND) Experiment on Chang'E4 Archived 3 January 2019 at the Wayback Machine. (PDF) Robert F. Wimmer-Schweingruber, S. Zhang, C. E. Hellweg, Jia Yu, etal. Institut für Experimentelle und Angewandte Physik. Germany.
  60. Mann, Adam (25 September 2020). "Moon safe for long-term human exploration, first surface radiation measurements show". Science. doi:10.1126/science.abe9386.
  61. Zhang, Shenyi (25 September 2020). "First measurements of the radiation dose on the lunar surface". Science. https://advances.sciencemag.org/content/6/39/eaaz1334.
  62. Geological Characteristics of Chang'e-4 Landing Site Archived 31 May 2018 at the Wayback Machine. (PDF) Jun Huang, Zhiyong Xiao, Jessica Flahaut, Mélissa Martinot, Xiao Xiao. 49th Lunar and Planetary Science Conference 2018 (LPI Contrib. No. 2083).
  63. Zheng, William (15 January 2019). "Chinese lunar lander's cotton seeds spring to life on far side of the moon". South China Morning Post. Retrieved 15 January 2019.
  64. Moon sees first cotton-seed sprout. Xinhua News. 15 January 2019.
  65. Change-4 Probe lands on the moon with "mysterious passenger" of CQU
  66. China Is About to Land Living Eggs on the Far Side of the Moon Archived 2 January 2019 at the Wayback Machine. Yasmin Tayag, Inverse. 2 January 2019.
  67. Rincon, Paul (2 January 2019). "Chang'e-4: China mission primed for landing on Moon's far side". BBC News. Archived from the original on 3 January 2019. Retrieved 3 January 2019.
  68. Space 2018: China mission will create miniature ecosystem on Moon Archived 4 April 2018 at the Wayback Machine. Karen Graham, Digital Journal. 6 January 2018.
  69. Forget the stratospheric chicken sandwich, China is sending potato seeds and silkworms to the Moon Archived 17 September 2017 at the Wayback Machine. Andrew Jones, GB Times. 14 June 2017.
  70. China Focus: Flowers on the Moon? China's Chang'e-4 to launch lunar spring Archived 27 December 2018 at the Wayback Machine. Xinhua (in English). 4 April 2018.
  71. Lunar nighttime brings end to Chang'e-4 biosphere experiment and cotton sprouts Archived 29 July 2019 at the Wayback Machine. Andrew Jones, GB Times. 16 January 2019.
  72. China's first plant to grow on the moon is already dead. Yong Xiong and Ben Westcott, CNN News. 17 January 2019.
  73. ECNS 2019-07-31
  74. "China Plans First Ever Landing on the Lunar Far Side". Space Daily. 22 May 2015. Archived from the original on 26 May 2015. Retrieved 26 May 2015.
  75. "Hsue-Shen Tsien". Mathematics Genealogy Project. Archived from the original on 9 December 2018. Retrieved 7 December 2018.
  76. "Chang'e 4: China probe lands on far side of the moon". The Guardian. 3 January 2019. Archived from the original on 3 January 2019. Retrieved 3 January 2019.
  77. Chang'e-4: Chinese rover now exploring Moon Archived 4 January 2019 at the Wayback Machine. Paul Rincon, BBC News. 4 January 2019.
  78. Mack, Eric. "China's Chang'e moon probe: We finally know exactly where the spacecraft landed". CNET. Retrieved 25 September 2019.
  79. Liu, Jianjun; Ren, Xin; Yan, Wei; Li, Chunlai; Zhang, He; Jia, Yang; Zeng, Xingguo; Chen, Wangli; Gao, Xingye; Liu, Dawei; Tan, Xu (24 September 2019). "Descent trajectory reconstruction and landing site positioning of Chang'E-4 on the lunar farside". Nature Communications. 10 (1): 4229. Bibcode:2019NatCo..10.4229L. doi:10.1038/s41467-019-12278-3. ISSN 2041-1723. PMC 6760200. PMID 31551413.
  80. Bartels, Meghan (15 February 2019). "China's Landing Site on the Far Side of the Moon Now Has a Name". Space.com. Retrieved 17 May 2020.
  81. Jones, Andrew (11 February 2019). "Chang'e-4 powers down for second lunar night". SpaceNews. Retrieved 1 August 2019.
  82. Caraiman, Vadim Ioan (11 February 2019). "Chinese Lunar Probe, Chang'e-4, Goes Standby Mode For The Second Lunar Night on The Dark Side of The Moon". Great Lakes Ledger. Retrieved 1 August 2019.
  83. Ouyang, Ziyuan; Zhang, Hongbo; Su, Yan; Wen, Weibin; Shu, Rong; Chen, Wangli; Zhang, Xiaoxia; Tan, Xu; Xu, Rui (May 2019). "Chang'E-4 initial spectroscopic identification of lunar far-side mantle-derived materials". Nature. 569 (7756): 378–382. Bibcode:2019Natur.569..378L. doi:10.1038/s41586-019-1189-0. ISSN 1476-4687. PMID 31092939. S2CID 205571018.
  84. Strickland, Ashley (15 May 2019). "Chinese mission uncovers secrets on the far side of the moon". CNN. Retrieved 16 May 2019.
  85. Rincon, Paul (15 May 2019). "Chang'e-4: Chinese rover 'confirms' Moon crater theory". BBC News. Retrieved 1 August 2019.
  86. Jones, Andrew (22 January 2020). "China releases huge batch of amazing Chang'e-4 images from moon's far side". Space.com. Retrieved 22 January 2020.
  87. Chang, Kenneth (26 February 2020). "China's Rover Finds Layers of Surprise Under Moon's Far Side - The Chang'e-4 mission, the first to land on the lunar far side, is demonstrating the promise and peril of using ground-penetrating radar in planetary science". The New York Times. Retrieved 27 February 2020.
  88. Li, Chunlai; et al. (26 February 2020). "The Moon's farside shallow subsurface structure unveiled by Chang'E-4 Lunar Penetrating Radar". Science Advances. 6 (9): eaay6898. doi:10.1126/sciadv.aay6898. PMC 7043921. PMID 32133404.
  89. Jones, Andrew (15 January 2019). "Chang'e-4 spacecraft enter lunar nighttime, China planning future missions, cooperation". SpaceNews. Retrieved 14 February 2019.
  90. David, Leonard (7 February 2019). "Farside Politics: The West Eyes Moon Cooperation with China". Scientific American. Retrieved 14 February 2019.
  91. Li, Zheng (13 February 2019). "Space a new realm for Sino-US cooperation". China Daily. Retrieved 14 February 2019.
  92. Needham, Kirsty (19 January 2019). "Red moon rising: China's mission to the far side". The Sydney Morning Herald.
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