Yutu-2

Yutu-2 (Chinese: 玉兔二号; pinyin: Yùtù Èrhào) 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 January 2019. Yutu-2 is currently operational as the longest-lived lunar rover[8] and the first lunar rover traversing the far side of the Moon.

Yutu-2
Yutu-2 rover on the Moon as seen by the Chang'e 4 lander
Mission typelunar rover
OperatorCNSA
Mission duration3 months (planned)[1]
Current: 4 years, 9 months, 23 days
Spacecraft properties
Launch massRover: 140 kg[2]
Landing mass140 kg
Dimensions1.5 × 1.0 × 1.0 m[3]
Start of mission
Launch date7 December 2018, 18:23 UTC[4]
RocketLong March 3B[5]
Launch siteXichang Satellite Launch Center
Lunar rover
Landing date3 January 2019, 02:26 UTC[6]
Landing siteVon Kármán crater in the South Pole-Aitken Basin
Distance driven1.455 km (0.904 mi)
as of 3 January 2023[7]
 

By January 2022, Yutu-2 had travelled a distance of more than 1,000 metres (3,300 ft) along the Moon's surface.[9][10] In September 2023, it had journeyed over 1.5 kilometres (0.93 mi) [11] and data from its ground penetrating radar (GPR) has been used by scientists to put together imagery of multiple layers deep beneath the surface of the far side of the moon.[12]

Overview
Mockup of Yutu-2 rover.
Mockup of Yutu-2 rover.

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,[13] 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.[14] 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,[13] 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."[15]

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. Yutu-2 rover was deployed about 12 hours after the landing.

Science payloads
  • 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.[16]
  • 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.[16]
  • 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.[17]

Cost

According to Wu Yanhua, the deputy director of the project, the cost of the entire mission was "close to building one kilometer of subway". The cost-per-kilometer of subway in China varies from 500 million yuan (about 72.6 million U.S. dollars) to 1.2 billion yuan (about 172.4 million U.S. dollars), depending on the difficulty of construction.[18]

Landing site

The landing site is within a crater called Von Kármán[19] (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.[20][21] 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.[22]

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.[23][24] In May 2019, it was reported that Chang'e 4 has identified what appear to be mantle rocks on the surface, its primary objective.[25][26][27]

In December 2019, Yutu 2 broke the lunar longevity record, previously held by the Soviet Union's Lunokhod 1 rover,[28] which operated on the lunar surface for eleven lunar days (321 Earth days) and traversed a total distance of 10.54 km (6.55 mi).[29]

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.[30][31]

In December 2021, the rover pictured what appeared to be a particularly prominent boulder, dubbed the "Mystery Hut" (神秘小屋), or "Moon Cube",[32][33] which it was intended to explore in the lunar days (earth months) ahead.[34][35] On 7 January 2022, news reported that the rover reached the destination area after traveling for a month, and found that the dubbed "Mystery Hut" structure was an "irregularly shaped rock";[36] to some, the rock looks a bit like a rabbit, along with a nearby much smaller rock that looks like a carrot, which may be even more fitting overall since the rover's name Yutu means "Jade Rabbit".[37]

The routing path of the Yutu-2 rover.

By September 2023, it had journeyed over 1.5 kilometres (0.93 mi) and was still operational and sending imagery.[11] Data from its two-channel ground penetrating radar (GPR) has been used by scientists to put together an image of multiple layers beneath the surface of the far side of the moon up to a depth of 300 meters.[12]

See also

References
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  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. "CNSA". China National Space Administration (in Chinese (China)). Archived from the original on 10 December 2018. Retrieved 8 December 2018.
  5. Launch Schedule 2018 Archived 16 August 2018 at the Wayback Machine. SpaceflightNow, 18 September 2018.
  6. 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.
  7. "【中国的玉兔2号月球车在月球背面行驶了近4年后仍在行驶】". 2022-09-18. Retrieved 2022-09-19.
  8. "Yutu 2 is now longest working rover on moon". english.www.gov.cn. Retrieved 2022-01-09.
  9. "Moon 'mystery hut' is just a rabbit-shaped rock, Chinese rover finds". Space.com. 11 January 2022. Retrieved 12 January 2022.
  10. "China's lunar rover Yutu 2 is on a mission to investigate mystery object on far side of the moon". 2021-12-05.
  11. "China's moon rover sends back photos as gift for Mid-Autumn Festival". 2023-09-30.
  12. "China's Yutu 2 rover reveals deep layers below far side of the moon". 2023-08-24.
  13. China Shoots for the Moon's Far Side. (PDF) IEEE.org. 2018.
  14. 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.
  15. 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.
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  18. China's latest Moon mission costs about as much as building 1 km of subway – Headlines, features, photo and videos from ecns.cn|china|news|chinanews|ecns|cns
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  22. "Hsue-Shen Tsien". Mathematics Genealogy Project. Archived from the original on 9 December 2018. Retrieved 7 December 2018.
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  25. 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.
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  32. Shannon Stirone (8 December 2021). "Moon Cube and Mysteries of the Solar System". The New York Times. Retrieved 27 December 2021.
  33. Kelvey, Jon (8 December 2021). "Look: Chinese Rover Spots a "Moon Cube," and Opens a New Lunar Mystery - While almost certainly a boulder or two, the enigmatic Moon Cube is nevertheless fascinating, and could help scientist understand how to live on the Moon". Inverse. Retrieved 27 December 2021.
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