Tianwen-1

Tianwen-1
NSSDC ID	2020-049A
Mission goal	Mars research
Client	National Space Agency of China
Launcher	Long March 5
construction
Takeoff mass	approx. 5000 kg
Course of the mission
Start date	July 23, 2020, 04:41 UTC
launch pad	Wenchang Cosmodrome
23rd July 2020 begin February 10, 2021 Entry into Mars orbit May 2021 Landing on Mars (planned)

Tianwen-1 ( Chinese 天問一號 / 天问一号, Pinyin Tianwen Yihao  - " sky Question 1") by Yinghuo-1 , the second from the People's Republic of China -built Mars probe . It consists of an orbiter , a lander and a rover . The probe was launched on July 23, 2020 with a Long March 5 launch vehicle and became the first Chinese Mars probe to orbit the planet on February 10, 2021.

Surname

The name refers to a poem ascribed to Qu Yuan (340–278 BC) in which he questioned the astronomy of the time, as it was depicted on wall paintings in the ancestral temples of the Chu kings: “Why is the ecliptic in 12 sections divided? ”Qu Yuan asked himself questions about heaven. In the original poem the questions remain without answers; Tianwen-1 and her successor probes should now find answers.

Position within the Mars program

The first preliminary talks for the Mars program of the People's Republic of China took place in June 2005. The official start of the program took place on March 26, 2007 with the signing of a partnership agreement between the China National Space Administration and Roscosmos . The first goal of the Mars program was the development and construction of a Mars orbiter. The Russian space probe Fobos-Grunt , which carried the Chinese orbiter Yinghuo-1 , did not get beyond a parking orbit after launch on November 9, 2011 and burned up on January 15, 2012 together with Yinghuo-1 over the East Pacific. As a result, China started its own Mars project.

Yinghuo-1 was supposed to photograph the Martian surface in order to find suitable places for a later landing. Apart from that, Wu Ji , the chief scientist at Yinghuo-1, and Wang Chi , who was responsible for the probe's payloads, had designed the mission primarily to explore the Martian ionosphere . These two tasks for Yinghuo-1 are now taken over by the orbiter of Tianwen-1: Before the rover lands, it is to map the surface of Mars for three months. Chief scientist and ionosphere specialist Wan Weixing put together the payloads for observing the space weather on Mars.

Planning, development and construction of the components

Tianwen-1, like the probes of the lunar program, was built by the Chinese Academy of Space Technology , with the Shanghai Academy of Space Technology contributing the orbiter. The scientific payloads were under the supervision of the National Center for Space Sciences of the Academy of Sciences in Beijing developed. In addition to its scientific role, the Mars mission also serves to test new technology that will be needed to bring Mars samples back to Earth in the 2030s.

At launch, the probe weighed a total of around 5 t, of which 3175 kg were accounted for by the fueled orbiter. The lander weighs around 1300 kg together with the rover without the heat shield.

Orbiter

After Prime Minister Li Keqiang approved the project on January 11, 2016 and the tasks had been assigned, the engineers in Shanghai began with the construction of the orbiter under the direction of Zhang Yuhua (张玉 花, * 1968). The form of a thick hexagonal coin with a hole in the middle was chosen, whereby the inner wall of the opening, through which the pressure is transmitted to the lander during take-off and during orbit control maneuvers, was not tubular but conical after initial attempts on the lander was designed tapering. Tests showed that in this way, with the same weight, the load-bearing capacity of the construction increased to 130% of the requirements. In the wide end of the opening are the spherical fuel tanks and the main engine, between the supporting cone and the hexagonal outer wall, the electronic systems and the accumulators fed by fold-out solar modules .

A first prototype was built and subjected to impact and temperature tests with the parabolic antenna mounted on the outer wall and the solar cell wings folded out. After these tests were satisfactory, a prototype identical to the final version was built in 2018, on which the electronics were tested, especially for electromagnetic compatibility , but also the functioning of the interfaces for communication between the orbiter and the launcher, the rover and the ground stations. Then the orbiter intended for the mission was built and integrated with the Lander-Rover group.

Countries

The lander will use a parachute for the descent, but mainly a powerful brake engine. The bottom plate of the heat shield has a diameter of 3.4 m. The ablative heat shield is designed similar to that of the landing capsule of the Shenzhou spaceships, but has been reinforced with a honeycomb structure. For Tianwen-1 the recipe of the material was changed in such a way that on the one hand it was stronger, on the other hand it had a lower density, i.e. it was lighter. In addition, the supporting honeycomb lattice was reinforced at the strongly curved points, the “edges” of the floor slab, so to speak, in order to keep it dimensionally stable in view of the aerodynamic forces acting there. The total of 70,000 honeycomb holes were filled with the material at once during the manufacture of the base plate. The upper part of the heat shield, on the other hand, consists of a non-ablative carbon fiber reinforced plastic of medium density, high strength and high thermal insulation. In turn, an ablative layer of paint is applied to this, which not only serves to protect against heat, but also protects the lander from the climatic influences on the Wenchang Cosmodrome with its salty air and from loss of material through outgassing in a vacuum.

The system integration phase was entered in April 2019 and the first tests of the lander-rover combination began under the supervision of Sun Zezhou , the probe's chief designer. On October 12, 2019, the first photo of the lander-rover combination, heat shielded and mounted on the orbiter, was released. On November 14, 2019, a public demonstration of the landing procedure took place at the multi-purpose test site for landings on alien celestial bodies of the Research Institute for Space-Related Mechanical and Electrical Engineering in Huailai County (about 100 km west of Beijing), to which the National Space Agency about 70 diplomats and Had invited journalists from countries with which China had collaborated on space projects in the past (including Germany , Holland , Italy , Brazil , Argentina , Saudi Arabia ). The gravitational force of Mars, which is only 1/3 compared to Earth, was simulated with a rope construction. The lander first reduced its speed to zero, looked for a free spot between the boulders scattered around the test site and then lowered itself there. On April 10, 2020, a group of lecturers and students from the Faculty of Space Technology at the Nanjing Aerospace University arrived at the Wenchang Cosmodrome to check the emergency beacon they had constructed on the real probe. This device is a kind of flight recorder which , in the event of an unplanned landing, is supposed to send a signal and transmit recorded data to the earth. The fluxgate magnetometer on board the orbiter was built by scientists from the Chinese University of Science and Technology in Hefei together with colleagues from the Institute for Space Research of the Austrian Academy of Sciences in Graz . In addition, scientists from the Institut de recherche en astrophysique et planétologie in Toulouse advised their colleagues from the Shanghai Institute for Technical Physics of the Chinese Academy of Sciences (中国科学院 上海 技术 物理 研究所) on the development of the device for laser-induced plasma spectroscopy , with which the rover can perform chemical To determine the composition of the Martian surface material.

Model of the Tianwen-1 Lander and Rover at an exhibition

rover

The rover is 2 × 1.65 × 0.8 meters in size and, at 240 kg, almost twice as heavy as Jade Hare 2 . While only 1/6 of the earth's gravity prevails on the moon, this value is around 1/3 on Mars . The Mars rover must therefore be built more robustly and requires more powerful engines. Since the nighttime temperatures on Mars near the equator are significantly milder at −85 ° C than on the moon (down to −180 ° C), the Mars rover does not have a radionuclide heating element , but draws its energy from solar cells, supplemented by two chemical hot water bottles ( see below "Heat collecting window").

Mission objectives

Technical goals

• Pivoting into a Mars orbit, descent through the Martian atmosphere, landing
• Orbiters and lander that act autonomously over a longer period of time
• Control and data reception over a distance of 400 million kilometers
• Gathering experience for the development of systems for autonomously operating deep space probes

Scientific goals

• Research into the topography and geological composition of Mars: creation of high-resolution maps of selected areas; Research into the origins and evolution of the geological composition of Mars.
• Research into the properties of the Mars regolith and the distribution of water ice therein: Measurement of the mineralogical composition of the Mars regolith, of weathering and sedimentation as well as the occurrence of these peculiarities over the whole of Mars; Search for water ice; Exploration of the layer structure of the Mars regolith.
• Research into the composition of the surface material: identification of the rock types on the surface of Mars; Exploration of secondary ore deposits on the Martian surface; Determination of the mineral content of the ores on the surface of Mars.
• Exploration of the ionosphere, space weather and surface weather of Mars: measurement of temperature, air pressure and wind systems on the surface; Research into the structure of the ionosphere and the seasonal changes in the Martian weather.
• Exploring the internal structure of Mars: measuring the magnetic field; Research into the early geological history of Mars, the distribution of the various types of rock inside the planet and measurement of its gravitational field .

The planetary geologist Ernst Hauber from the German Aerospace Center criticized the fact that it is not intended to make the data collected by the probe freely available to the scientific public, as is customary at ESA and NASA , but that it is initially provided by the National authority for science, technology and industry in national defense should be kept under lock and key. There are three levels of access authorization for the ground segment of the Mars program of the People's Republic of China : The raw data - after five to six months - are in principle only passed on to the manufacturers of the payloads so that they can improve their devices. Tables, images and graphics created from the raw data are made available to registered users after 12 months, who in turn are divided into an “inner circle” (内部 用户, Nèibù Yònghù ) and “outsiders” (外部 用户, Wàibù Yònghù ).

Scientific instruments

Orbiter

• Medium resolution camera (100 m per pixel over a width of 400 km at an altitude of 400 km; red, green, blue)
• High resolution camera ( panchromatic : 2.5 m (in focus 0.5 m) per pixel, color images: 10 m (in focus 2 m) per pixel over a width of 9 km at a height of 265 km)
• Ground penetrating radar for researching underground structures, with sand down to a depth of a few hundred meters, with ice caps down to a depth of a few kilometers, with a resolution of 1 m each
• Spectrometer for Mars ores (visible light up to near infrared or 0.45-3.40 μm; resolution 10 nm in the visible range, 12 nm at 1.0-2.0 μm, 25 nm from 2.0 μm)
• Mars magnetometer for researching the interaction between the Martian ionosphere , magnetosphere and solar wind (measuring range: around 2000  nT , resolution: 0.01 nT)
• Particle detector for ions and neutral particles to study the interaction between the solar wind and the Martian atmosphere and to investigate their escape
• Particle detector for energetic particles for mapping their spatial distribution during the flight to Mars and in the Martian area

rover

Model of the rover at the IAC 2018 in Bremen

• Topographic camera (2048 × 2048 pixels, color images in the range 0.5 m - ∞)
• Multispectral camera (480 nm, 525 nm, 650 nm, 700 nm, 800 nm, 900 nm, 950 nm, 1000 nm, i.e. blue to infrared )
• Ground penetrating radar with two channels : a low-frequency channel for a depth of 10–100 m with a resolution of a few meters and a high-frequency channel for a depth of 3–10 m with a resolution of a few centimeters
• Device for measuring the composition of the Martian surface material using laser-induced plasma spectroscopy ( Si , Al , Fe , Mg , Ca , Na , O , C , H , Mn , Ti , S etc.) and infrared spectrometer (850-2400 nm with a resolution of 12 nm)
• Device for measuring the magnetic field on the surface of Mars (measuring range: around 2000 nT, resolution: 0.01 nT, temperature-stable 0.01 nT / ° C, works with magnetometer on orbiter)
• Weather station (temperature: −120 ° C to +50 ° C with a resolution of 0.1 ° C, air pressure: 1–1500  Pa with a resolution of 0.1 Pa, wind speed: 0–70 m / s with a resolution of 0.1 m / s, wind direction: 0 ° –360 ° with a resolution of 5 °, microphone: 20 Hz – 20 kHz with a sensitivity of 50 mV / Pa)

In order to get results as quickly as possible after the landing in early summer 2021, the center for lunar exploration and space projects of the National Space Agency began in early July 2019 to put together a group of scientists under the direction of electrical engineer Jie Degang (节 德刚, * 1978) who should familiarize themselves with the probe's instruments in advance and think about specific research projects into which the data obtained from the payloads could flow. The target group of the recruitment campaign were young scientists from Chinese universities and research institutes; Foreigners were not eligible.

Mission flow

Start and transfer track

Launch of Tianwen-1 on July 23, 2020

A Changzheng 5 acted as the launch vehicle for the probe . Between July 23 and August 5, 2020 there was a daily start window of 30 minutes each. Since Earth and Mars moved relative to each other during this period, this required a slightly different orbit every ten minutes. So there were a total of 42 possible trajectories. These were programmed into the rocket control and the rocket selected the appropriate flight path at the time of launch.

The 5 t probe was launched on July 23, 2020 at 04:41 a.m. UTC . About three minutes after take-off, the four kerosene liquid oxygen boosters separated from the two-stage launcher. Six minutes after launch, the missile was out of the atmosphere and the payload fairing was opened and ejected. Eight minutes after take-off, the first stage was disconnected and the upper stage ignited its two engines. After another three and a half minutes, the engines were switched off and the rocket went into unpowered flight for about 16 minutes, a technique that had been tested on December 27, 2019 on the third flight of this type of rocket. The engines were then re-ignited for 7.5 minutes and the trajectory was corrected. 36 minutes after launch, the rocket had traveled around 10,000 km and reached the transfer orbit to Mars at an altitude of 200 km. The probe was separated from the upper stage of the rocket and flew unpowered towards Mars at a speed of 11.5 km / s (a little more than the necessary escape speed of 11.2 km / s). For this purpose, a so-called " Hohmann Bahn " was chosen, which is only possible once every 26 months for three and a half weeks, but requires less fuel at takeoff and enables a higher payload weight.

At 05:21 UTC, the Zapala deep-space station in Argentina (a branch of the Xi'an satellite control center ) first captured the probe. 13:37 the deep space station followed Giyamusi and shortly after 17 pm, the Deep Space Station Kashgar . Using long-base interferometry , it was possible to confirm from the three stations that the probe was on the correct path. On August 1, 2020 at 23:00 UTC - after 230 hours of flight or 3 million kilometers traveled - the first orbit correction maneuver was carried out as planned. The orbiter's main engine, originally developed for the Chang'e 5 lunar probe, with a thrust of 3 kN, was put into operation for 20 seconds. In addition to regulating direction and speed, this was primarily used to collect data on the behavior of the engine, which was included in the calculations for further orbit maneuvers. The second orbit correction maneuver took place on September 20, 2020 at 3:00 p.m. after a 60-day flight or 160 million kilometers traveled. Here, four of the eight position control thrusters with 120 N thrust each were put into operation for 20 seconds. In addition to a small orbit correction, this maneuver was also primarily used to test the engines.

Hohmann transfer orbit to Mars

For a visual inspection of the probe during the flight, the Shanghai Academy for Space Technology , which is responsible for the construction of the orbiter, had developed a system in which a small camera weighing a total of 950 g is ejected with a low impulse (the actual camera weighs 680 g, the rest is part of the mechanism), which is equipped with a wide-angle lens and a CCD sensor of 800 × 600 or 1600 × 1200 pixels on the front and back . While the camera, constantly overturning, disappears into the vastness of space, it takes a photo every second. The photos are sent from the camera to the probe via a WLAN with a range of 400 m. This in turn transmits the images back to the Beijing Space Control Center . Tianwen-1 has several of these single-use cameras, the first of which was deployed on October 1, 2020, China's national holiday.

On October 9, 2020 at 3:00 p.m. UTC, the Kashgar and Giyamusi deep-space stations were involved in a major 8-minute orbit change maneuver. Another, minimal path correction took place on October 28, 2020 at 2:00 p.m. Here, 8 of the 12 attitude control thrusters were briefly ignited at 25 N, also to check their functionality. By this time, 97 days after launch, the probe had covered 256 million kilometers, about half the planned distance. One last orbit correction maneuver before entering Mars orbit took place on February 5, 2021 at 12:00 UTC at a distance of 1.1 million kilometers from Mars, with 8 of the 12 attitude control thrusters of 25 N ignited again for 12 seconds. The probe had already taken the first photo of Mars from a distance of 2.2 million kilometers and sent it to the ground segment in Beijing. By this time, 197 days after launch, the probe had traveled 465 million kilometers on its transfer orbit.

Parking orbit

On February 10, 2021 at 11:52 a.m. UTC, the probe ignited its main engine for 15 minutes and swiveled into an elliptical orbit of 400 × 180,000 km with an orbit of 10 days around Mars, inclined by 10 ° to the equator. Along with the landing, this was one of the mission's most critical maneuvers. If the engine had not ignited at exactly the right time, the probe would either have crashed on Mars or - like the Japanese probe Nozomi in 2003 - flew past the planet. For orbital maneuvers the orbiter of Tianwen-1 comprises a total of 21 engines: a main engine with 3  kN thrust 8 attitude control thrusters 120 N thrust and 12 attitude control thrusters with 25 N pushing force all of the Academy of liquid-propellant rocket technology produced. On February 12, 2021, the Chinese New Year , the Center for Lunar Exploration and Space Projects of the National Space Agency published two videos of the pivoting process recorded by various on-board cameras.

Further planned process

From February 15, 2021, the probe will take several orbital correction maneuvers in a lower parking orbit with a periares of 265 km, an inclination of 86.9 ° (i.e. an almost polar orbit) and an orbital period of only two Martian days, from which it will take three Carries out a preliminary exploration of the two possible landing areas for months. As of July 2020 these are:

Map of Mars with the two possible landing areas and the locations of previous Mars landings

• A depression at the southern end of the Utopia Planitia at longitude 110.318 ° east and latitude 24.748 ° north, which was formed at the end of the Hesperian period about 2 billion years ago. This is the primary goal.
• A point in the southeast of the Utopia Planitia, where lava from the Elysium Mons volcano flowed onto the plain. This is the reserve target.

Due to the very low orbit, the probe with its high-resolution camera in the focus of the lens can take pictures with a resolution of 0.5 m per pixel. After the technicians have determined the final landing point on the basis of the recordings made by the orbiter (both photographic and with ground penetrating radar and spectrometer), the Lander Rover group is expected to be decoupled from the orbiter in mid-May 2021. The orbiter then performs another orbital maneuver and enters orbit from which it can act as a relay satellite for the rover. For the power supply after disconnection from the orbiter, the lander relies on lithium-carbon-fluoride batteries developed by the China Electronics Technology Group Corporation , which discharge little during the seven-month flight, even in strong sunlight, and weigh 5 kg less than a corresponding set Lithium-ion batteries .

About 5 hours after separating from the orbiter, the Lander-Rover group enters the atmosphere at an altitude of 125 km at an angle of 11.2 °, where they initially reach a speed of 4.8 for 5 minutes due to their flow resistance alone km / s reduced to 460 m / s. Then the parachute opens at a height of 4 km and brakes the probe from 460 m / s to 95 m / s for 90 seconds. At a height of 1.5 km above the surface, the parachute is dropped, the brake engine ignites and, with its thrust of 7.5 kN, reduces the fall speed in a further 90 seconds to just 3.6 m / s, at a lateral speed of maximum 0.9 m / s. The lander remains in the air for a short time 100 m above the ground so that, as with the Chang'e-3 and Chang'e-4 lunar probes, it can independently search for a level space free of boulders - the lander has 20 smaller engines for maneuvering each with 250 N thrust and six with 25 N - to which it then slowly descends. The last impulse on contact with the ground is cushioned by the four landing legs.

On the 8th Martian day after landing, the rover is supposed to roll off the loading area, photograph the surroundings with the stereo camera on the mast on its front (the multispectral camera is arranged between the two “eyes”) and begin exploring Mars. The nominal maximum speed of the rover is 200 meters per hour. Although he can raise his ground clearance a little using the arms to which the six wheels are attached, he generally avoids obstacles, for which he can move sideways by turning the wheels by 90 °. This means that the distance actually covered will be relatively short.

Since the solar constant , i.e. the solar radiation averaged over many years, is less than half as large on Mars as near the earth, the rover not only has two solar modules , like the moon rover Jadehase 2 , but four, which are constantly aligned with the sun while the Mondrover only one of the two solar modules is movable. In order to save energy for heating, the rover only works from noon, when the temperature on the surface of Mars is highest and most favorable for the measuring instruments. Part of the energy generated by the solar modules is used to operate the rover, the rest is used to charge an accumulator, which allows the rover to continue working until after sunset. There are also two round “heat collecting windows” on the top of the rover. Among them is n- undecane , which melts during the Martian day and in the evening, when it solidifies again when the ambient temperature drops - the substance has a melting point of −26 ° C - releases around 80% of the stored heat. For comparison: the rover's solar modules are only 30% efficient.

The weather on Mars can change rapidly, with dust storms that greatly reduce solar radiation. Therefore the rover has an autonomous self-monitoring system. If he notices that his energy reserves - both in terms of electricity and heat - are only sufficient for a limited period of time, it switches itself off, goes into sleep mode and only resumes work when the weather is better .

During the first 90 days on Mars (a good three earth months, the expected lifespan of the rover), the orbiter primarily functions as a relay satellite for the rover, but it also begins scientific exploration of the surface of Mars. Then the orbiter is brought into its actual mission orbit with an orbit correction maneuver, from which it carries out intensive long-range reconnaissance. If the rover should still be functional by then (the moon rover Jadehase 2 turned out to be extremely durable), the orbiter should also continue to function as a relay satellite. The data transfer takes place via the antennas of the ground segment of the Mars program in Miyun , Kunming and Wuqing .

Others

On July 24, 2020, the center for lunar exploration and space projects of the National Space Agency launched an international competition, in which all those interested in space could submit proposals for the name of the rover by August 12, 2020. Then a commission made a pre-selection of the ten best proposals - Nezha , Red Hare (the horse of Lü Bu ), Qilin, etc. - from which all people who care about this topic, in an internet vote from January 20 to 28. February 2021 can choose three names. A commission then selects the final name from these three names.

Web links

Commons : Tianwen-1  - collection of pictures, videos and audio files

• Special issue of the journal for deep space exploration on the individual systems of Tianwen-1 (Chinese with English summaries)
• Special issue of the journal for deep space exploration for the protection of Mars from contamination with terrestrial microorganisms (Chinese with English summaries)
• Website of the Shanghai Institute of Technical Physics (English)
• Dennis Normile: Mars mission would put China among space leaders. Science Mag. June 2020, doi: 10.1126 / science.abd5026

Individual evidence

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2. ↑ Red-White-Red on the Way to Mars. Kleine Zeitung, print, July 23, 2020, accessed July 23, 2020. - "Questions to Heaven"
3. ↑ ^{a b c} Andrew Jones: China's Tianwen-1 enters orbit around Mars . Spacenews, February 10, 2021.
4. ↑ Helwig Schmidt-Glintzer : History of Chinese Literature. Scherz Verlag , Bern 1990, p. 36 f.
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28. ↑ 舒 嵘 et al .:深 空 探测 中 的 激光 诱导 击穿 光谱 探测 仪. In: jdse.bit.edu.cn. March 21, 2018, accessed July 25, 2020 (Chinese).  This institute had already built the laser rangefinder and the three-dimensional imaging laser scanner for the automatic obstacle avoidance and landing system of the Chang'e-4 lunar probe .
29. ↑ ^{a b} 火星 探测 步步 惊心 ， 不是 探 月 的 简单 “复制” 和 “粘贴”. In: tech.sina.com.cn. August 3, 2020, accessed August 4, 2020 (Chinese). 
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31. ↑ ^{a b} 耿 言 et al. - Geng, Yan et al .:深 空 探 测 学 报 - 我国 首次 火星 探测 任务 - China's First Mars Exploration Mission - Journal of Deep Space Exploration. (PDF; 367 kB) In: jdse.bit.edu.cn. June 28, 2018, accessed June 4, 2020 (Chinese). 
32. ↑ Dirk Assendorpf: Hello Mars. In: THE TIME. No. 24, June 4, 2020, page 33.
33. ↑ ^{a b} 刘建军 - Liu, Jianjun:中国 首次 火星 探测 任务 地面 应用 系统. In: jdse.bit.edu.cn. May 5, 2015, accessed June 5, 2020 (Chinese). 
34. ↑ ^{a b} 中国 电 科 以 技术 创新 为 “天 问 一号” 乘风破浪 保驾 护航. In: cnsa.gov.cn. July 23, 2020, accessed July 25, 2020 (Chinese). 
35. ↑ 孔令 高 et al .:自主 火星 探测 高 集成 离子 与 中性 粒子 分析 仪. In: jdse.bit.edu.cn. December 13, 2018, accessed July 25, 2020 (Chinese). 
36. ↑ 李春 来et al .:中国 首次 火星 探测 任务 科学 目标 与 有效 载荷 配置. In: jdse.bit.edu.cn. March 21, 2018, accessed July 27, 2020 (Chinese). 
37. ↑ Zhou Bin et al .: The subsurface penetrating radar on the rover of China's Mars 2020 mission. In: ieeexplore.ieee.org. September 22, 2016, accessed July 5, 2019 . 
38. ↑ 许琦敏: “天 问 一号” 启程 ， 探测 火星 它 带上 了 哪些 “神器”？ In: / 中国科学院. 中国. July 23, 2020, accessed July 27, 2020 (Chinese). 
39. ↑ The air pressure at the zero level of Mars is 600 Pa, the primary landing site of the rover is about 4000 m below the zero level.
40. Jump up ↑ Jia Yingzhuo, Fan Yu, Zou Yongliao: Scientific Objectives and Payloads of Chinese First Mars Mission. In: nssc.cas.cn. September 6, 2018, accessed July 25, 2020 (Chinese). 
41. ↑ 闫 明星 - Yan, Mingxing:优秀 毕业生 节 德刚 ： 一个 全面 发展 的 当代 大学生. In: cy.jxstnu.edu.cn. April 14, 2008, Retrieved September 21, 2019 (Chinese). 
42. ↑ 节 德刚 - Jie, Degang:首次 火星 探测 任务 科学 目标 先期 研究 团队 招募 公告. In: clep.org.cn. July 5, 2019, accessed September 21, 2019 (Chinese). 
43. ↑ 刘 桢 珂:这次 “大 火箭” 飞 得 更快 ， “天 问 一号” 成功 入轨！ In: photo.china.com.cn. July 23, 2020, accessed July 23, 2020 (Chinese). 
44. ↑ 深 空 探测 新 一步！ 我国 首次 火星 探测 任务 探测器 成功 起航. In: cnsa.gov.cn. July 24, 2020, accessed July 26, 2020 (Chinese). 
45. ↑ ^{a b c} 奔 火 ： 飞向 “乌托邦”. In: spaceflightfans.cn. July 24, 2020, accessed July 24, 2020 (Chinese). 
46. ↑ “胖 五” 为了 “奔 火” 有多 拼? In: cnsa.gov.cn. July 24, 2020, accessed July 26, 2020 (Chinese). 
47. ↑ 吕炳宏 、 付毅飞:中国 深 空 测控 网 将 全程 护送 “天 问 一号” 探 火. In: stdaily.com. July 24, 2020, accessed July 24, 2020 (Chinese).  The photo shows the Kashgar underground station.
48. ↑ 赵聪:一 文 解读 嫦娥 五号 月 面 起飞. In: spaceflightfans.cn. December 5, 2020, accessed December 5, 2020 (Chinese). 
49. ↑ 天 问 一号 探测器 完成 第 一次 轨道 中途 修正. In: spaceflightfans.cn. August 2, 2020, accessed August 2, 2020 (Chinese). 
50. ↑ 胡 喆: “天 问 一号” 探测器 完成 第二 次 轨道 中途 修正. In: xinhuanet.com. September 21, 2020, accessed September 21, 2020 (Chinese). 
51. ↑ 马永 香:太空 中 的 中国 国旗！ 来自 天 问 一号 的 自拍！ In: spaceflightfans.cn. October 1, 2020, accessed October 1, 2020 (Chinese). 
52. ↑ 中国 探 月 航天:天 外 送 祝福 ， 月圆 迎 华诞 —— 天 问 一号 以 “自拍 国旗” 祝福 祖国 71 华诞. In: mp.weixin.qq.com. October 1, 2020, accessed October 1, 2020 (Chinese). 
53. ↑ 钱 中 兵: “天 问 一号” 探测器 顺利 完成 深 空 机动. In: xinhuanet.com. October 10, 2020, accessed October 10, 2020 (Chinese). 
54. ↑ 王世玉 、 杨 璐: “天 问 一号” 完成 第三 次 轨道 中途 修正 已 飞行 97 天. In: news.cctv.com. October 29, 2020, accessed October 29, 2020 (Chinese). 
55. ↑ 王亚平:天 问 一号 探测器 顺利 完成 第四 次 轨道 中途 修正. In: spaceflightfans.cn. February 6, 2021, accessed February 6, 2021 (Chinese). 
56. ↑ 天 问 一号 完成 第四 次 轨道 中途 修正 传 回首 幅 火星 图像. In: clep.org.cn. February 5, 2021, accessed February 5, 2021 (Chinese). 
57. ↑ 蔡 彬:航天 科技 集团 六 院 78 台 发动机 千吨 动力 开启 中国 首次 探 火 之 旅. In: guoqing.china.com.cn. July 23, 2020, accessed July 24, 2020 (Chinese). 
58. ↑ 国家 航天 局 发布 天 问 一号 探测器 火星 捕获 过程 影像 1. In: clep.org.cn. February 12, 2021, accessed February 12, 2021 (Chinese). 
59. ↑ 国家 航天 局 发布 天 问 一号 探测器 火星 捕获 过程 影像 2. In: clep.org.cn. February 12, 2021, accessed February 12, 2021 (Chinese). 
60. ↑ 连 政: “天 问 一号” 探测器 成功 进入 火星 轨道. In: guancha.cn. February 10, 2021, accessed February 11, 2021 (Chinese).  Contains video of the orbit correction maneuvers.
61. ↑ 天 问 一号 探测器 成功 实施 火星 捕获 中国 首次 火星 探测 任务 环绕 火星 获得 成功. In: clep.org.cn. February 10, 2021, accessed February 10, 2021 (Chinese). 
62. ↑ 探 月 工程 嫦娥 五号 任务 有关 情况 发布会. In: cnsa.gov.cn. December 17, 2020, accessed December 18, 2020 (Chinese). 
63. ↑ 张建松 、 周琳: 2 分钟 为 你 模拟 飞向 火星 全 过程！ In: xinhuanet.com. July 23, 2020, accessed July 23, 2020 (Chinese).  Contains video of the flight and the maneuvers.
64. ↑ 乔学荣 、 郭 际 、 米 娟:高 比 能量 锂 氟化 碳 电池 在 深 深 空 探测器 上 的 应用 试验 研究. In: jdse.bit.edu.cn. February 11, 2020, accessed July 25, 2020 (Chinese). 
65. ^ Andrew Jones: China's first Mars spacecraft undergoing integration for 2020 launch. In: spacenews.com. May 29, 2019, accessed July 5, 2019 . 
66. ↑ 2020 中国 火星 探测 计划 （根据 叶院士 报告 整理）. In: spaceflightfans.cn. March 14, 2018, accessed July 5, 2019 (Chinese). 
67. ↑ 天 问 一号 四大 不可 不知 的 亮点. In: tech.sina.com.cn. July 15, 2020, accessed July 16, 2020 (Chinese). 
68. ↑ 林晓 弈 - Lin, Xiaoyi:火星 探测器 着陆 细节！ In: Weibo.com. June 1, 2020, accessed June 1, 2020 (Chinese). 
69. ↑ 胡 喆:我国 第 一辆 火星 车 正式 启动 全球 征 名. In: gov.cn. July 24, 2020, accessed July 25, 2020 (Chinese). 
70. ↑ 胡 喆:麒麟 、 哪吒 、 风火轮 …… 你 “Pick” 哪 一个？ In: xinhuanet.com. January 18, 2021, accessed January 18, 2021 (Chinese).