Chang'e 5-T1

Chang'e 5-T1
NSSDC ID	2014-065A
Mission goal	Earth moon
Client	National Space Agency (CNSA)
Manufacturer	Chinese Academy of Space Technology (CAST)
Launcher	Long March 3
construction
Takeoff mass	2450 kg
Course of the mission
Start date	October 23, 2014, 18:00 UTC
launch pad	Xichang Cosmodrome
23 October 2014 begin October 27, 2014 Flyby on the back of the moon October 31, 2014 Return capsule lands in Inner Mongolia November 1, 2014 Orbiter goes into earth-moon transfer orbit 23rd November 2014 Arrival near the moon November 27, 2014 Lissajous orbit around L 2 January 11, 2015 Orbit around the moon

Chang'e 5-T1 ( Chinese  嫦娥五號探路星  /  嫦娥五号探路星 , Pinyin Chang'e Wǔhào Tànlù Xing , "spies satellite for Chang'e-5") was an experimental lunar probe , which at 23 October 2014 by the CNSA (China National Space Administration). The probe circled the moon , and then returned to earth. It tested the re-entry into the earth's atmosphere from a lunar orbit.

The probe is part of the Chinese lunar program , which includes numerous lunar probes. Chang'e-1 and Chang'e-2 performed a topographical and spectrographic image of the lunar surface from orbit . Chang'e-3 and Chang'e-4 landed on the moon, each launching a rover. The future Chang'e-5 and Chang'e-6 missions will bring moon rocks to earth. China has plans for a future manned mission to the moon.

mission

After the Chang'e-3 mission, which brought a rover to the moon, was only partially successful, the test mission Chang'e 5-T1 was started before the successor mission Chang'e-4. With it, the re-entry into the earth's atmosphere from a lunar orbit and the targeted landing should be tested. The lunar probe was developed by the Chinese Academy of Space Technology under the direction of Prof. Ye Peijian . It consisted of the 2-ton orbiter, a further development of the Chang'e-2 probe, and the 300 kg return capsule, which was a 1: 8 scale version of the landing capsule of the Shenzhou spaceships. These dimensions corresponded to the announced Chang'e-5 probe.

The probe weighed 2,450 kg with fuel for the orbiter and the secondary payload, and the payload fairing had a diameter of four meters. The launch was with a modified Changzheng 3C rocket on October 24, 2014 at 2 a.m. local time from the Xichang Cosmodrome in Sichuan .

Free return path

Two-part descent

Lissajous orbit around the L ₂ point

On a free return path, Chang'e 5-T1 arrived at the moon three days later, rounded it at a distance of 13,000 km and returned to earth. In the early morning of November 1, 2014, Beijing time, the return capsule separated from the orbiter at an altitude of 5000 km. The latter initially remained in earth orbit, while the return capsule, after a two-part descent with atmospheric braking , similar to the Soviet Zond lunar probes 1968–1970, landed safely at the Dörbed landing site in Inner Mongolia at 06:42 local time , where the Astronauts from the Shenzhou missions landed. The two-part descent, called skip-glide in English because of the skip-glide that is reminiscent of a bouncing stone thrown at a shallow angle over a water surface , was necessary because the probe came back from the moon at a very high speed of 11.2 km / s and the Return capsule still hit the atmosphere at 10.7 km / s even after a brief braking maneuver. In the event of a direct, steep re-entry into the atmosphere, there would have been a strong thermal load on the heat shield.

Meanwhile, on November 1st, the orbiter made two orbital correction maneuvers that transformed its originally circular orbit into an elongated ellipse, with the perigee only 600 km from the earth's surface, while the apogee was 540,000 km away. On November 9th and November 17th, 2014, a further orbit correction maneuver took place in the furthest and closest point. A transfer orbit to the moon was thus achieved.

A demanding experiment was carried out during the flight to the moon. Normally, the orbit tracking and location of the probes takes place via the Chinese Deep Space Network , a joint venture between the military satellite control network and the civilian VLBI network of the Chinese Academy of Sciences . Weak signals were now used to determine the location; the terrestrial navigation satellites - Ye Peijian called the American GPS - and the Chinese Beidou satellites - inadvertently emit into space via side lobes and back lobes , a method that the engineers called “leak signal -Navigation "(漏 导航, Pinyin Lòu Dǎoháng ) is called. For this purpose, Prof. Ye and his team had equipped the orbiter with a particularly sensitive receiver, and with the help of said leak signals it was actually possible to pinpoint the location of the probe to 100 m and its speed to 5 cm / s during the entire transfer process to the moon determine. It is planned to use this cost-saving navigation method for transport spaceships that will shuttle back and forth between the earth and the moon in the future.

After another orbital correction maneuver on November 21, the orbiter arrived near the moon on November 23 and used its gravity to go to the Lagrange point L ₂ behind the moon. Until then, the procedure was similar to flying the Elsternbrücke four years later. The Chang'e 5-T1 orbiter then did not take a Halo orbit around the L ₂ point on November 27 , but a Lissajous orbit , with an X-axis of 20,000 km and a Y-axis of 40,000 km and a Z-axis of 35,000 km (the moon is 3500 km in diameter); the period of circulation was 14 days.

After a minor orbit correction on November 28, the orbiter remained in its Lissajous orbit until January 4, 2015. On that day the probe left the L ₂ point and began an elliptical orbit with axis lengths of 300 km and 200 km respectively around the moon itself, which it reached in the early morning of January 11, 2015, Beijing time. After two further orbit correction maneuvers on January 12th and 13th, the probe entered a circular orbit with a diameter of 200 km and an orbit duration of 127 minutes, inclined by 43.7 ° to the lunar equator and the planned orbit for Chang'e- 5 (the previous orbiters Chang'e-1 and Chang'e-2 had a polar orbit with an inclination of 90 °).

On February 6 and 7, 2015, a large-scale exercise took place in the Beijing Space Control Center of the People's Liberation Army, during which the technicians there, together with engineers from the manufacturing company CAST, practiced the flight maneuvers that the real Chang'e-5 orbiter has to perform while its lander takes soil samples on the lunar surface. Here, not only the adjustment of the trajectory was practiced - in the real case the orbiter has to pick up the transport capsule that brings the soil samples from the moon into orbit - but also continuous orbit monitoring over several days via the network of ground stations coordinated by the Xi'an satellite control center .

From March 3 to 7, 2015, another exercise took place with the same participants, during which the rendezvous between orbiter and transport capsule was practiced. For this purpose, the originally round orbit of the orbiter was changed with three orbit correction maneuvers so that the point closest to the moon was only 18 km above the moon's surface, while the aposelenum was 180 km away from the moon. It was then simulated how the transport capsule - now played by the Chang'e 5-T1 orbiter - flies behind the orbiter from a point at an altitude of 18 km, approaches it ever closer and finally docks.

In April 2015, the orbit of the orbiter was gradually lowered to 100 km, then 50 km and finally only 15 km, so that it can take pictures of the planned landing area of ​​the real probe at Mons Rümker in Oceanus Procellarum with its experimental CMOS camera with a resolution of 0.97 m. The orbiter is still in orbit, its downlink signal can be received at 2234.520 MHz (as of 2019).

M4 project

The 4M payload ( Manfred Memorial Moon Mission ) flew as a secondary payload . This project by the German OHB was the world's first privately financed moon mission. The 4M mission was carried out by LUXSpace . The payload weighed 14 kilograms and contained two scientific instruments:

• A radio signal to test a new way of locating the probe. Radio amateurs were called upon to record this signal and send the result to LuxSpace.
• A dosimeter that was provided by the Spanish iC-Málaga . It measured the radiation intensity over the entire duration of the mission.

4M sent its last message on November 11, 2014.

Mission Profile

• Start: Xichang, October 23, 2014 18:00 UTC
• Planned mission duration: 196 hours (8.17 days)
• Flyby the moon: 97 hours after being launched into orbit (4.04 days)
• Periseles : about 13,000 km from the surface of the moon
• Distance of the moon to the earth during the flyby: ~ 373,000 km

See also

• List of space probes
• Chronology of the moon missions
• Space of the People's Republic of China

literature

• Chang'e-5 T1. In: Bernd Leitenberger: With space probes to the planetary spaces: New beginning until today 1993 to 2018 , Edition Raumfahrt Kompakt, Norderstedt 2018, ISBN 978-3-74606-544-1 , pp. 363–366

Individual evidence

1. ↑ ^{a b} Worldwide Launch Schedule. Spaceflight Now, October 23, 2014, accessed November 28, 2013 . 
2. ↑ Chinese sample returns from flight around the moon . spaceflightnow.com. November 1, 2014. Retrieved November 10, 2014.
3. ↑ “舞 娣” 素描 —— 揭秘 探 月 工程 三期 飞行 试验 器. In: http://www.clep.org.cn/ . October 24, 2014, accessed May 11, 2019 (Chinese). 
4. ↑ 米格: 解码 嫦娥 五 试验 星. In: https://new.qq.com/ . January 23, 2014, accessed May 14, 2019 (Chinese). 
5. ↑ 叶培 建 委员 ： “嫦娥 五号” 探路 者 “小飞” “打 前 站” 有 “高招”. In: http://www.clep.org.cn/ . March 2, 2016, Retrieved May 16, 2019 (Chinese). 
6. ↑ 张 素 、 蔡金 曼: 中国 探 月 再入 返回 飞行器 服务 舱 飞抵 地 月 L2 点. In: http://www.chinanews.com/ . November 29, 2014, Retrieved May 11, 2019 (Chinese). 
7. ↑ 蔡金 曼 、 邹维荣: 探 月 三期 再入 返回 飞行器 服务 舱 进入 200 公里 环 月圆 轨道. In: http://zz.81.cn/ . January 13, 2015, accessed May 16, 2019 (Chinese). 
8. ↑ 张 素: 中国 探 月 工程 三期 再入 返回 飞行器 在 轨 验证 嫦娥 五号. In: http://www.chinanews.com/ . February 8, 2015, accessed May 16, 2019 (Chinese). 
9. ↑ 探 月 “小飞” 成功 模拟 嫦娥 五号 两 器 对接 飞 控 过程. In: http://news.kedo.gov.cn/ . March 9, 2015, accessed May 16, 2019 (Chinese). 
10. ↑ Chang'e 5 Test Mission Updates. In: http://www.spaceflight101.net/ . March 9, 2015, accessed May 17, 2019 . 
11. ↑ 叶培 建 委员 ： “嫦娥 五号” 探路 者 “小飞” “打 前 站” 有 “高招”. In: http://www.clep.org.cn/ . March 2, 2016, Retrieved May 16, 2019 (Chinese). 
12. ^ Matthias Bopp: Sounds from Space Ships to the Moon. In: http://www.dd1us.de/ . February 13, 2018, accessed May 18, 2019 . 
13. ↑ Roland Prösch: Technical Handbook for Satellite Monitoring: Edition 2019. Books on Demand, Norderstedt 2019, p. 465.
14. ^ First Private Moon Mission to Launch on Chinese Rocket Today . Space.com. October 23, 2014. Retrieved November 10, 2014.
15. ↑ Contest . LuxSpace. Archived from the original on October 24, 2014. Retrieved November 10, 2014.
16. ↑ China Readies Moon Mission for Launch Next Week . Space.com. October 14, 2014. Retrieved November 10, 2014.
17. ↑ China Poised to Launch Next Moon Mission on Thursday . Space.com. October 22, 2014. Retrieved November 10, 2014.
18. ↑ 4M (Manfred Memorial Moon Mission). Retrieved December 3, 2017 . 
19. ^ The mission . LuxSpace. Archived from the original on September 13, 2014. Retrieved November 10, 2014.
20. ↑ ANS-278 AMSAT News Service Weekly Bulletins . AMSAT News Service. October 5, 2014. Retrieved November 10, 2014.
21. ↑ 天津 航天 爱好者 谈 嫦娥 五号 飞行 试验 器 ( Memento from October 19, 2014 in the Internet Archive )