Tianwen-1

Summary

Tianwen-1
Mars Global Remote Sensing Orbiter and Small Rover (2020).png
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
OperatorChina National Space Administration (CNSA)
COSPAR ID2020-049A
SATCAT no.45935
Mission duration225 days, 18 hours, 49 minutes
Orbiter: 2 Earth years (planned)
Rover: 90 sols (planned)[4]
Spacecraft properties
Spacecraft typeOrbiter, lander, rover, TW-1 Deployable Camera (TDC)
ManufacturerChina National Space Administration
Launch massTotal: 5,000 kg (11,000 lb)
Orbiter: 3,175 kg (7,000 lb)
Rover:240 kg (530 lb)
DimensionsRover: 2.6 × 3 × 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 (CASC)
Mars orbiter
Spacecraft componentOrbiter
Orbital insertion10 February 2021[6][7]
Mars lander
Spacecraft componentLander
Landing dateMay 2021 (planned)[6]
Landing siteUtopia Planitia[8]
Mars rover
Spacecraft componentRover
Landing dateMay 2021 (planned)[6]
Landing siteUtopia Planitia[8]
Chinese Planetary Exploration Mars logo
China Mars Exploration mission logo
(Chinese: 中国行星探测) Mars logo  

Tianwen-1 (TW-1; simplified Chinese: 天问; traditional Chinese: 天問; lit. 'heavenly questions') is an interplanetary mission by the China National Space Administration (CNSA) to send a robotic spacecraft to Mars, consisting of an orbiter, deployable camera, lander and rover. The spacecraft, with a total mass of nearly five tons, is one of the heaviest probes launched to Mars and carries 13 scientific instruments.

The mission was successfully launched from the Wenchang Spacecraft Launch Site on 23 July 2020[9] on a Long March 5 heavy-lift launch vehicle. After 7 months of transit, it entered orbit around Mars on 10 February 2021.[10][7] For the next 2 months the space probe will study the target site from a reconnaissance orbit, then in May or June 2021 the landing is planned to begin with the release of the capsule. It is projected to make an atmospheric entry followed by a descent phase under parachute, after which the lander will use its propulsion to land smoothly on Mars. If all goes according to plan, the lander will then deploy the rover designed to explore the surface for 90 Martian days. The orbiter will serve as a telecommunications relay during the rover's primary mission and will position itself in an orbit more conducive to observations while retaining its role of relay.

The scientific objectives of the mission relate to the geology of Mars, the current and past presence of water, the internal structure of the planet, the identification of minerals and different types of rocks on the surface, as well as the characterization of the space environment and atmosphere of Mars. The mission will attempt to land its rover on Mars in May 2021.

If successful, China will become the second country to deploy a rover on Mars, after the United States. It will also be the third country to achieve a successful soft landing on Mars, after the Soviet Union and the United States.[4][11]

Tianwen-1 mission 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 United Arab Emirates (Hope orbiter) and the United States (Mars 2020 with the Perseverance rover and Ingenuity helicopter drone).

Naming

The name Tianwen, meaning "questions to heaven" or "quest for heavenly truth", comes from the long poem of the same name written by Qu Yuan (about 340–278 BC), a poet of ancient China.[12][13]

Overview

Model of Phobos-Grunt presented at the Paris Air Show in 2011. The Chinese satellite Yinghuo-1 is in the center, it's marked label 3.
Tianwen-1 launching on 23 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 spacecraft and experiments eventually reentered in the atmosphere of Earth in January 2012.[14] China subsequently began an independent Mars project,[15] and the current mission which was formally approved by Chinese authorities in 2016, became a reality 5 years later.[16]

A schematic of the Tianwen-1 probe

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.[17] 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]

The TW-1 Deployable Camera (TDC) deployed from the orbiter in September 2020 while en route to Mars. Its mission was to photograph the Tianwen-1 orbiter and the lander's heat shield. Two wide-angle lenses on the deployable camera were programmed to one image a second. The images were transmitted back to Tianwen-1 via a wireless radio link, then downlinked back to teams in China.[18]

Mission objectives

This is China's first interplanetary mission, as well as its first independent probe to Mars. The goal is therefore first of all to validate the communication and control technologies in deep space, the placing in orbit around the planet and the landing on its surface. The orbiter must also make it possible to locate a site for a future return of Martian samples.

From a scientific point of view, the mission must meet 5 objectives:

  1. Study the morphology and geological structure of Mars, as well as its evolution and its causes. To do this, the probe will analyze the topography of the planet with precise data from characteristic regions such as the dry bed of rivers, the reliefs of volcanoes, wind erosion, glaciers at the poles, etc. The two cameras present on the orbiter are dedicated to this objective.
  2. Study the characteristics of the surface and underground layers of the soil of Mars, as well as the distribution of water ice. This is the role of the radars present on the orbiter and the rover.
  3. Study the composition and type of rocks as well as the minerals and elements present on the surface of Mars. Analyze the carbonate or weathering minerals present in ancient lakes, rivers and other landscapes resulting from the past presence of water on the planet, such as hematites, lamellar silicates, sulphate hydrates or even perchlorate minerals in order to establish the link with the watery past of Mars. The spectrometers on board the orbiter and the rover as well as the multispectral camera are dedicated to this objective.
  4. Study the ionosphere, the climate, the seasons and more generally the atmosphere of Mars, both in its near space environment and on its surface. This is the role of the two particle detectors present on the orbiter as well as of the rover's weather station.
  5. Study the internal structure of Mars, its magnetic field, the history of its geological evolution, the internal distribution of its mass and its gravitational field. The magnetometers as well as the radars present on the orbiter and the rover are dedicated to this objective.[19]

The aims of the mission include searching for evidence of current and past life, producing surface maps, characterizing soil composition and water ice distribution, and examining the Martian atmosphere, and in particular its ionosphere.[20]

The mission also serves as a technology demonstration that will be needed for an anticipated Chinese Mars sample-return mission proposed for the 2030s.[21] Tianwen-1 will also cache rock and soil samples for retrieval by the later sample-return mission.[22]

Mission planning

Tianwen-1 transfer orbit and trajectory correction maneuvers (TCM)
Planned orbital trajectory at Mars
Map of Mars with the two possible landing areas of Tianwen-1, and the locations of previous Mars landings

In late 2019, the Xi'an Aerospace Propulsion Institute, a subsidiary of China Aerospace Science and Technology Corporation (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 7,500 N (1,700 lbf) of thrust. The spacecraft's supersonic parachute system had also been successfully tested.[16]

CNSA initially focused on the Chryse Planitia and Elysium Mons regions of Mars in its search for possible landing sites. However, in September 2019 during a joint meeting in Geneva, in Switzerland, 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.[16]

In July 2020, CNSA provided landing coordinates of 110.318° east longitude and 24.748° north latitude, within the southern portion of Utopia Planitia, as the specific primary landing site. The area appears to provide a relatively safe place for a landing attempt but is also of great scientific interest, according to Alfred McEwen, director of the Planetary Image Research Laboratory at the University of Arizona.[8] Simulated landings have been performed as part of mission preparations by the Beijing Institute of Space Mechanics and Electricity.[23]

By 23 January 2020, the Long March 5 Y4 rocket's hydrogen-oxygen engine had completed a 100-seconds test, which was the last engine test prior to the final assembly of the launch vehicle. It successfully launched on 23 July 2020.[9]

TW-1 Deployable Camera

In September 2020 Tianwen-1 deployed the TW-1 Deployable Camera (TDC), a small satellite with two cameras that took photos of and tested a radio connection with Tianwen-1.[18] Tianwen-1 also completed two mid-course orbital corrections and performed self diagnostics on multiple payloads.[24] 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.[25]

Entering Mars orbit

Tianwen-1 spacecraft was launched by Long March 5 Heavy-lift launch vehicle on 23 July 2020. Having traveled for about seven months, it entered Mars orbit on 10 February 2021 by performing a burn of its engines to slow it down just enough to be captured by Mars' gravitational pull. The orbiter will spend the next few months scanning the surface to refine the target landing zone for the lander/rover, which is planned to occur in May or June 2021.[26][27][13] It will approach at about 265 km (165 mi) to Mars' surface, allowing a high-resolution camera to return images to the Earth and to map the landing site in Utopia Planitia.[28]

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:[29]

Orbiter

  • Medium-Resolution Camera (MRC) with a resolution of 100 m from a 400 km orbit
  • 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)
  • Mars Energetic Particle Analyzer[29]

Rover

  • Ground-Penetrating Radar (GPR), to image about 100 m (330 ft) below the Martian surface[11]
  • Mars Surface Magnetic Field Detector (MSMFD)
  • Mars Meteorological Measurement Instrument (MMMI)
  • Mars Surface Compound Detector (MSCD), combines laser-induced breakdown spectroscopy and infrared spectroscopy [30]
  • Multi-Spectrum Camera (MSC)
  • Navigation and Topography Camera (NTC)

International collaborations

Video outlining the Tianwen-1 mission

Argentina's Comisión Nacional de Actividades Espaciales (CONAE) is collaborating on Tianwen-1 by way of a Chinese-run tracking station installed in Las Lajas, Neuquén. 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.[31]

France's Institute for Research in Astrophysics and Planetology (IRAP) in Toulouse, in France, 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".[31]

Austria's Austrian Research Promotion Agency (FFG) aided 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.[31]

Acheron FossaeAcidalia PlanitiaAlba MonsAmazonis PlanitiaAonia PlanitiaArabia TerraArcadia PlanitiaArgentea PlanumArgyre PlanitiaChryse PlanitiaClaritas FossaeCydonia MensaeDaedalia PlanumElysium MonsElysium PlanitiaGale craterHadriaca PateraHellas MontesHellas PlanitiaHesperia PlanumHolden craterIcaria PlanumIsidis PlanitiaJezero craterLomonosov craterLucus PlanumLycus SulciLyot craterLunae PlanumMalea PlanumMaraldi craterMareotis FossaeMareotis TempeMargaritifer TerraMie craterMilankovič craterNepenthes MensaeNereidum MontesNilosyrtis MensaeNoachis TerraOlympica FossaeOlympus MonsPlanum AustralePromethei TerraProtonilus MensaeSirenumSisyphi PlanumSolis PlanumSyria PlanumTantalus FossaeTempe TerraTerra CimmeriaTerra SabaeaTerra SirenumTharsis MontesTractus CatenaTyrrhen TerraUlysses PateraUranius PateraUtopia PlanitiaValles MarinerisVastitas BorealisXanthe TerraMap of Mars
The image above contains clickable linksInteractive image map of the global topography of Mars, overlain with locations of Mars landers and rovers. Hover your mouse over the image to see the names of over 60 prominent geographic features, and click to link to them. Coloring of the base map indicates relative elevations, based on data from the Mars Orbiter Laser Altimeter on NASA's Mars Global Surveyor. Whites and browns indicate the highest elevations (+12 to +8 km); followed by pinks and reds (+8 to +3 km); yellow is 0 km; greens and blues are lower elevations (down to −8 km). Axes are latitude and longitude; Polar regions are noted.
(See also: Mars map, Mars Memorials, Mars Memorials map) (view • discuss)
(   Active Rover  Active Lander  Future )
Beagle 2
Bradbury Landing
Deep Space 2
Columbia Memorial Station
InSight Landing
Mars 2
Mars 3
Mars 6
Mars Polar Lander
Challenger Memorial Station
Mars 2020
Green Valley
Schiaparelli EDM lander
Carl Sagan Memorial Station
Columbia Memorial Station
Tianwen-1
Thomas Mutch Memorial Station
Gerald Soffen Memorial Station

See also

References

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  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
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