Tianwen-1

Tianwen-1 (TW-1) (tentatively Huoxing-1, HX-1 during development[9]) is an interplanetary mission to Mars by the China National Space Administration (CNSA) to send a robotic spacecraft, which consists of an orbiter, a lander and a rover.[10] The mission was successfully launched from the Wenchang Spacecraft Launch Site on 23 July 2020[11] with a Long March 5 heavy-lift rocket, and is currently en route to Mars, having already traveled about 3 million kilometers to date. Tianwen-1 carried out its first mid-course correction on August 2, 2020 and will make two more course corrections and a deep-space maneuver as it makes its way to the planet over the next seven months. The spacecraft has begun to conduct scientific operations with the Mars Energetic Particle Analyzer, mounted on the orbiter, which has already transmitted data back to ground control. [12][13] Its stated objectives are to search for evidence of both current and past life, and to assess the planet's environment.[4][14]

Tianwen-1
Tianwen-1 undergoing tests in 2019. The silver capsule on top houses the lander and rover, and the gold bottom half with the rocket engine is the orbiter.
NamesHuoxing-1 (火星-1) (2018–2020)[1][2][3]
Mission typePlanetary science with an orbiter, lander and rover
OperatorCNSA
COSPAR ID2020-049A
SATCAT no.45935
Mission duration25 days, 20 hours, 54 minutes (since launch)
Orbiter: 2 Earth years (planned)
Rover: 90 sols (planned)[4]
Spacecraft properties
Spacecraft typeOrbiter, lander, rover
Launch massTotal: 5,000 kg (11,000 lb)
Orbiter: 3,175 kg (7,000 lb)
Rover：240 kg (530 lb)
DimensionsRover: 2.0 × 1.65 × 1.85 metres
Start of mission
Launch date23 July 2020, 04:41:15 UTC[5]
RocketLong March 5
Launch siteWenchang, LC-101
ContractorChina Aerospace Science and Technology Corporation
Mars orbiter
Spacecraft componentOrbiter
Orbital insertion11 to 24 February 2021[6]
Mars lander
Spacecraft componentLander[7]
Landing date23 April 2021[6] (proposed)
Landing siteUtopia Planitia (2 preliminary sites)[8]
Mars rover
Spacecraft componentRover
Landing dateAfter 23 April 2021[6] (proposed)
Landing siteUtopia Planitia (2 preliminary sites)[8]

Chinese Planetary Exploration
(Chinese: 中国行星探测) Mars logo  

The name "Tianwen" (simplified Chinese: 天问; traditional Chinese: 天問; lit.: 'heavenly questions') comes from the long poem of the same name written by Qu Yuan (about 340–278 BC), one of the greatest poets of Ancient China.[15] It is a poem of a series of questions starting with how the universe was created.

Tianwen-1 was the second of three space missions sent toward Mars during the July 2020 Mars launch window, with missions also launched by the national space agencies of the United Arab Emirates (Hope orbiter) and the United States (Mars 2020, with an orbiter, lander, and rover). All three are expected to arrive at Mars in February 2021.

Overview
Launch of Tianwen-1 on a Long March 5 in July 2020

China's Mars program started in partnership with Russia. In November 2011, the Russian spacecraft Fobos-Grunt, destined for Mars and Phobos, was launched from Baikonur Cosmodrome. The Russian spacecraft carried with it an attached secondary spacecraft, the Yinghuo-1, which was intended to become China's first Mars orbiter (Fobos-Grunt also carried experiments from The Planetary Society and Bulgaria). However, Fobos-Grunt's main propulsion unit failed to boost the Mars-bound stack from its initial Earth parking orbit and the combined multinational spacecrafts and experiments eventually reentered Earth's atmosphere in January 2012[16]. China subsequently began an independent Mars project[17] and the current mission, which was formally approved by Chinese authorities in early 2016[8], is the result.

The new Chinese Mars spacecraft, consisting of an orbiter and a lander with an attached rover, is developed by the China Aerospace Science and Technology Corporation (CASC) and managed by the National Space Science Centre (NSSC) in Beijing.[12] The lander portion of the spacecraft will use a parachute and a retrorocket in order to achieve landing on the Martian surface.[18] If the landing is successful, the lander would then release a rover. This rover will be powered by solar panels and is expected to probe the Martian surface with radar and to perform chemical analyses on the soil; it would also look for biomolecules and biosignatures.[4]

Scientific objectives

The aims of the mission may include the following: find evidence for current and past life, produce Martian surface maps, characterize Martian soil composition and water ice distribution, examine the Martian atmosphere, and in particular, its ionosphere, among others.[19] Simulated Martian landings have been performed as part of mission preparations by the Beijing Institute of Space Mechanics and Electricity.[10]

The current Mars mission also would serve as a demonstration of technology that will be needed for an anticipated Chinese Mars sample-return mission proposed for the 2030s.[12] There was also a plan that involved using the current mission to cache Martian rock and soil samples for retrieval by the later sample-return mission.[20]

Mission planning
Planned orbital trajectory at Mars.
Tianwen-1 transfer orbit and trajectory correction maneuvers (TCM).

In late 2019, the Xi'an Aerospace Propulsion Institute, a subsidiary of CASC, stated that the performance and control of the future spacecraft's propulsion system has been verified and had passed all requisite pre-flight tests, including tests for hovering, hazard avoidance, deceleration, and landing. The main component of the lander's propulsion system consists of a single engine that provides 7500 newtons of thrust. The spacecraft's supersonic parachute system had also been successfully tested previously.[8]

CNSA initially focused on the Chryse Planitia and on the Elysium Mons regions of Mars in its search for possible landing sites for the lander and its associated rover. However, in September 2019, during a joint meeting in Geneva of the European Planetary Science Congress-Division for Planetary Sciences, Chinese presenters announced that two preliminary sites in the Utopia Planitia region of Mars have instead been chosen for the anticipated landing attempt, with each site having a landing ellipse of approximately 100 by 40 kilometres.[8]

On 23 January 2020, China Youth Daily reported that, according to sources from CASC, the Mars probe will be launched in July 2020 by the Long March 5 Y4 carrier rocket. This was the first time that China has officially announced the month in which the probe will be launched from Earth.[21] The newspaper also reported that the Long March 5 Y4 rocket's hydrogen-oxygen engine has completed a 100-seconds test, which was the last engine test prior to the final assembly of the carrier rocket. It successfully launched on time.[22]

Scientific instruments
Mockup of the rover at the 69th International Astronautical Congress

To achieve the scientific objectives of the mission, the Tianwen-1 orbiter and rover are equipped with 13 instruments:[23]

Orbiter
  • Medium Resolution Camera (MRC) with a resolution of 100 m from a 400 km orbit[10]
  • High Resolution Camera (HRC) with a resolution of 2 m from a 400 km orbit
  • Mars Magnetometer (MM)
  • Mars Mineralogy Spectrometer (MMS), to determine elementary composition
  • Orbiter Subsurface Radar (OSR)
  • Mars Ion and Neutral Particle Analyzer (MINPA)[6]
  • Mars Energetic Particle Analyzer [23]
Rover[24]
  • Ground-Penetrating Radar (GPR), to image about 100 metres (330 ft) below the Martian surface[14]
  • Mars Surface Magnetic Field Detector (MSMFD)
  • Mars Meteorological Measurement Instrument (MMMI)
  • Mars Surface Compound Detector (MSCD)
  • Multi-Spectrum Camera (MSC)
  • Navigation and Topography Camera (NTC)[6]

International collaborations

Argentina's CONAE is collaborating on Tianwen-1 by way of a Chinese-run tracking station installed in Las Lajas, Argentina. The facility played a previous role in China's landing of the Chang'e-4 spacecraft on the far side of the moon in January 2019.[25]

France's Institute for Research in Astrophysics and Planetology (IRAP) in Toulouse is collaborating on the Tianwen-1 rover. Sylvestre Maurice of IRAP said, "For their Laser Induced Breakdown Spectroscopy (LIBS) instrument, we have delivered a calibration target that is a French duplicate of a target which is on NASA's Curiosity Mars rover. The idea is to see how the two datasets compare."[25]

Austria's Austrian Research Promotion Agency (FFG), had been reported to aid in the development of a magnetometer installed on the Chinese Mars orbiter. The Space Research Institute of the Austrian Academy of Sciences in Graz has confirmed the group's contribution to the Tianwen-1 magnetometer and helped with the calibration of the flight instrument.[25]

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See also

References
  1. "中国火星探测器露真容 明年发射". 12 October 2019.
  2. The Global Exploration Roadmap. NASA International Space Exploration Coordination Group. January 2018 This article incorporates text from this source, which is in the public domain.
  3. China's Deep Space Exploration Roadmap. 2018.
  4. "China Exclusive: China's aim to explore Mars". Xinhua News. 21 March 2016. Retrieved 24 March 2016.
  5. "Tianwen-1: Rocket carrying China's Mars probe blasts off". China Global Television Network. 23 July 2020. Retrieved 23 July 2020.
  6. 2020中国火星探测计划（根据叶院士报告整理 Published in 2018.
  7. "It's official: China's first Mars lander debuts". China Global Television Network. 14 November 2019. Retrieved 8 January 2020.
  8. Jones, Andrew (8 November 2019). "China Says Its Mars Landing Technology Is Ready For 2020". IEEE Spectrum. Retrieved 30 December 2019.
  9. "中国火星探测器露真容 明年发射". 12 October 2019.
  10. Jones, Andrew (9 February 2018). "China simulates Mars landing in preparation for 2020 mission". GBTimes. Retrieved 3 March 2018.
  11. Jones, Andrew (23 July 2020). "Tianwen-1 launches for Mars, marking dawn of Chinese interplanetary exploration". spacenews.com. Retrieved 23 July 2020.
  12. Jones, Andrew (22 February 2016). "China is racing to make the 2020 launch window to Mars". GBTimes. Retrieved 22 February 2016.
  13. Lei, Zhao (3 August 2020). "Mars probe makes first mid-course adjustment". Chinadaily. Retrieved 3 August 2020.
  14. The subsurface penetrating radar on the rover of China's Mars 2020 mission. B. Zhou, S. X. Shen, Y. C. Ji, etal. 2016 16th International Conference on Ground Penetrating Radar (GPR). 13–16 June 2016.
  15. "China's First Mars Exploration Mission Named Tianwen-1". XinhuaNet. 24 April 2020. Retrieved 24 April 2020.
  16. Zolotukhin, Alexei (15 January 2012). "Russian Phobos-Grunt Mars probe falls in Pacific Ocean". RIA Novosti. Retrieved 16 January 2012. Phobos-Grunt fragments have crashed down in the Pacific Ocean
  17. Nan, Wu (24 June 2014). "Next stop – Mars: China aims to send rover to Red Planet within six years". South China Morning Post. Retrieved 23 February 2016.
  18. Jones, Andrew (21 March 2016). "China reveals more details of its 2020 Mars mission". GB Times. Retrieved 22 March 2016.
  19. Zhou; et al. (13–16 June 2016). "The subsurface penetrating radar on the rover of China's Mars 2020 mission". 2016 16th International Conference on Ground Penetrating Radar (GPR). pp. 1–4. doi:10.1109/ICGPR.2016.7572700. ISBN 978-1-5090-5181-6.
  20. China Plans To Land A Rover On Mars In 2020. Alexandra Lozovschi, Inquisitr. January 17, 2019.
  21. "China to launch Mars probe in July". ChinaDaily.com. 23 January 2020. Retrieved 23 January 2020.
  22. Tianwen-1 launch
  23. "China launches robotic mission to orbit, land, and drive on Mars". Spaceflight Now. 23 July 2020. Retrieved 24 July 2020.
  24. Tianwen-1 Mars Rover and Lander
  25. https://www.space.com/china-mars-mission-tianwen-1-international-partners.html
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