Chang'e-2

Chang'e-2
Artist's impression of Chang'e-2
Mission goal	Earth moon
Client	CNSA
Launcher	CZ-3C
construction
Takeoff mass	2.48 t
Course of the mission
Start date	October 1, 2010
launch pad	Xichang Cosmodrome
Oct 1, 2010 begin Oct 6, 2010 Reaching orbit around the moon June 9, 2011 Leaving the lunar orbit April 2012 Leaving the Lagrangian point L2 December 13, 2012 Fly by Toutatis February 14, 2014 Last contact in interplanetary space

Chang'e-2 ( Chinese  嫦娥 二號  /  嫦娥 二号 , Pinyin Cháng'é Èrhào ) is the second space probe of the China National Space Administration (CNSA) and the second mission in the lunar program of the People's Republic of China . The probe took off on October 1, 2010 at 10:59 a.m. UTC from the spaceport in Xichang . The probe circled the moon for eight months to measure and photograph it.

The mission served as preparation for Chang'e-3's soft landing in 2013. In December 2012, the probe reached the asteroid (4179) Toutatis .

The costs are put at around 900 million yuan or just under 100 million euros.

construction

Chang'e-2 was originally intended as a backup for Chang'e-1 . The probe is also based on the DFH-3 bus . Solar cells (just under 2 kW) generate the electrical energy and swirl wheels and cold gas nozzles ensure position control .

The eight instruments are further developments of those of the previous mission. Particularly noteworthy is the CCD camera developed by a research group led by Prof. Xu Zhihai (徐 之 海, * 1964) from the then Faculty of Optoelectronics (光电 信息 工程学 系) at Zhejiang University ; its resolution is now seven meters from a height of about 100 kilometers. By lowering the lunar orbit at the end of the mission, a resolution of one meter can be achieved. The other instruments are a detector consisting of three individual measuring devices, as in Chang'e-1, for measuring particle radiation from the sun , a laser altimeter, an optical, an X-ray and a gamma spectrometer, and a microwave radiometer.

The refined instruments, especially the high-resolution camera, generate significantly more data than the payloads of the previous mission. This required an expansion of the device developed by the National Center for Space Science of the Academy of Sciences, which compresses the collected data and caches it until it can be radioed to the Chinese VLBI network when the probe is in line of sight with China . The data memory of Chang'e-2 now has a capacity of 144 GB, three times as high as that of Chang'e-1, the speed of data processing has been increased by more than a hundred times. With the old technology of the predecessor probe, this would have meant a multiple increase in volume and weight as well as a more than tenfold increase in power consumption. However, by using the latest technology, the development group succeeded in increasing the volume and weight of the device by only 60%, and power consumption only doubled.

Mission history

In contrast to its predecessor Chang'e-1 , Chang'e-2 flew directly to the moon with a larger use of fuel . This shortened the flight time from almost 14 to 5 days. At 100 kilometers above the surface, the lunar orbit was only half that of Chang'e-1. In May 2011, the point closest to the moon was lowered further and was only 15 kilometers above the Sinus Iridum . Recordings of the planned landing area of ​​the rover Chang'e-3 could be made with a resolution of 1.5 meters per pixel .

On June 9, 2011, the Chang'e-2 engines were fired, and the probe left orbit towards the Lagrangian point L _{2 of} the sun-earth system, where it stayed for about ten months, measured the solar wind and China had important operational experience a deep space probe delivered. In April 2012 it left the Lagrangian point L _{2 to} reach the near-earth asteroid (4179) Toutatis . On December 13, 2012 at 08:30 UTC, the probe passed Toutatis at a distance of 3.2 km and a relative speed of 10.73 km / s. A series of pictures was taken from a distance of 93 to 240 km. Chang'e-2 then broke into interplanetary space on an elongated elliptical orbit around the sun (similar to that of a periodic comet ). On February 14, 2014, Chang'e-2 was already 70 million kilometers from Earth. Connectivity was then lost, but the probe is expected to return to 7 million kilometers in 2029 after reaching the apogee of its orbit 300 million kilometers away . When it was last contacted in February 2014, Chang'e-2 was still in very good condition.

Up until then, the Beijing Space Control Center had been able to gather valuable experience with regard to the optimal use of fuel and the laws that lead to the inexorable orbital lowering of each probe. But as with Chang'e-1, where uninterrupted monitoring and control of the probe was possible during the critical phase up to the entry into lunar orbit only thanks to the support of ESA with its worldwide distributed ESTRACK stations, now the Limits to China's deep space capabilities. While the large telescopes of the Chinese VLBI network, which observe radio sources in distant galaxies during regular research operations , received the telemetry signals from Chang'e-2 without any problems, the transmitters in the ground stations under the Xi'an satellite control center had reached the limit of their range whereby the Beijing Space Control Center was unable to intervene in the event of extraordinary incidents or hazards. This was already clear to everyone involved on June 9, 2011, when the probe left lunar orbit, and it was already then planned to have two additional deep space ground stations (深 空 测控 站, Deep Space Antenna ) for future missions in Kashgar and Giyamusi. to be built with parabolic antennas of 35 m or 64 m. The data that were collected during the orbit tracking of the probe on its way into interplanetary space later formed an important basis for planning the Tianwen-1 mission to Mars .

See also

• List of space probes
• Chronology of the moon missions
• Space of the People's Republic of China
• List of man-made objects on the moon

literature

• Chang'e-2. In: Bernd Leitenberger: With space probes to the planetary spaces: New beginning until today 1993 to 2018 , Edition Raumfahrt Kompakt, Norderstedt 2018, ISBN 978-3-7460-6544-1 , pp. 298-302

Web links

• Five amazing engineering camera videos from Chang'e-2

Individual evidence

1. ↑ China's 2nd lunar probe Chang'e-2 blasts off. In: http://www.chinadaily.com.cn . October 1, 2010, accessed January 2, 2019 . 
2. ↑ 祝 梅: 浙江 大学 光电 科学 与 工程 学院 教授 徐 之 海 - 我 向 宇宙 奔跑 不 停步. In: https://zjnews.zjol.com.cn . February 8, 2019, Retrieved April 29, 2019 (Chinese). 
3. ↑ 曹向群: 啊！ 浙大 光仪 ， 我 是 您 的 铁杆 粉丝. In: http://opt.zju.edu.cn . October 19, 2011, Retrieved April 29, 2019 (Chinese). 
4. ↑ 徐 之 海: 徐 之 海. In: https://www.zju.edu.cn . Retrieved April 29, 2019 (Chinese). 
5. ^ Günther Glatzel: Second Chinese lunar probe on the launch pad. Raumfahrer.net, September 27, 2010, accessed September 28, 2010 . 
6. ↑ 探 月 工程. In: http://www.nssc.cas.cn . Retrieved April 25, 2019 (Chinese). 
7. ↑ Günther Glatzel: Chang'e 2 should go to the moon faster. Raumfahrer.net, September 5, 2010, accessed September 28, 2010 . 
8. ↑ Tilmann Althaus: What is China's moon probe Chang'e-2 doing? astronomie-heute.de, April 8, 2011, accessed June 12, 2011 . 
9. ↑ Günther Glatzel: Chang`e 2: From the moon satellite to the space probe. raumfahrer.net, June 10, 2011, accessed on June 11, 2011 . 
10. ^ Günther Glatzel: Chang'e 2 on the road again. raumfahrer.net, June 19, 2012, accessed June 20, 2012 . 
11. ↑ Discovery News: Chinese probe buzzes asteroid Toutatis. December 15, 2012, accessed January 23, 2017 . 
12. ↑ For comparison: Mars is about 230 million kilometers from the sun.
13. ↑ 田 兆 运 、 祁登峰: 嫦娥 二号 创造 中国 深 空 探测 7000 万 公里 最 远距离 纪录. In: http://news.ifeng.com . February 14, 2014, accessed April 29, 2019 (Chinese). 
14. ↑ 陈玉明: 嫦娥 二号 飞离 月球 奔向 距 地球 150 万 公里 的 深 空. In: http://www.gov.cn . June 9, 2011, Retrieved April 30, 2019 (Chinese). 
15. ↑ 嫦娥 一号 所 拍 中国 首 幅 月球 全 图 发布. In: http://mil.news.sina.com.cn . November 12, 2008, Retrieved May 1, 2019 (Chinese). 
16. ↑ 董光亮 et al .: 中国 深 空 测控 系统 建设 与 技术 发展. In: http://jdse.bit.edu.cn . Retrieved May 4, 2019 (Chinese).  The antenna in Giyamusi ended up being 66 m in diameter.
17. ↑ “天 问 一号” ： 中国 首次 火星 之 旅. In: k.sina.com.cn. July 10, 2020, accessed July 11, 2020 (Chinese).