Tianwen-1

China's planetary exploration program is officially dubbed the " Series". "Tianwen-1" () is the program's first mission, and subsequent planetary missions will be numbered sequentially. The name is from the poem of the same name written by Qu Yuan (340–278 BC). The title means "Questions to Tian", a Chinese term for both the sky and heavens. -1's rover is named '''' (), after a Chinese mytho-historical figure usually associated with fire and light. The name was chosen through an online poll held from January to February 2021. == Earlier attempt ==

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 Bulgarian Academy of Sciences and the American Planetary Society). 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 the atmosphere of Earth in January 2012. In 2014, China subsequently began an independent Mars project. == Mission overview ==

on Hainan, 23 July 2020 The new Mars spacecraft, consisting of an orbiter and a lander with an attached rover, was developed by the China Aerospace Science and Technology Corporation (CASC) and is managed by the National Space Science Centre (NSSC) in Beijing. The mission was formally approved in 2016. On 14 November 2019, CNSA invited some foreign embassies and international organizations to witness hovering and obstacle avoidance test for the Mars Lander of China's first Mars exploration mission at the extraterrestrial celestial landing test site. It was the first public appearance of China's Mars exploration mission. As the mission preparation proceeded, in April 2020, the mission was formally named "-1". On , -1 was launched from Wenchang Spacecraft Launch Site on the island of Hainan atop a Long March 5 heavy-lift launch vehicle. In September 2020, the -1 orbiter deployed the -1 First Deployable Camera (TDC-1), a small satellite with two cameras that took photos of and tested a radio connection with -1. After payload checkouts, the spacecraft began scientific operations with the Mars Energetic Particle Analyzer, mounted on the orbiter, which transmitted initial data back to ground control. The lander/rover portion of the mission began its Martian landing attempt on 14 May 2021. About nine minutes after the aeroshell housing the lander/rover combination entered the Martian atmosphere, the lander (carrying the rover) safely touched down in the Utopia Planitia region on Mars. This rover is powered by solar panels and probed the Martian surface with radar and conducted chemical analyses on the soil; it also looked for biomolecules and biosignatures. == Mission objectives ==

This is the CNSA's first interplanetary mission, as well as its first independent probe to Mars. The primary goal is therefore to validate China's deep space communications and control technologies, as well as the Administration's ability to successfully orbit and land spacecraft. From a scientific point of view, the mission must meet five objectives: • Study the geological structure of Mars and that structure's historical evolution. To do this, the probe will analyze topographical data from characteristic regions such as dry riverbeds, the reliefs of volcanoes, glaciers at the poles, areas affected by wind erosion, etc. The two cameras present on the orbiter are dedicated to this objective. • Study the characteristics of both the surface and underground layers of Martian soil, as well as the distribution of water ice. This is the role of the radars present on the orbiter and the rover. • Study the composition and type of rocks on the Martian surface, carbonate minerals present in ancient lakes, rivers, and other landscapes resulting from the past presence of water on the planet, and weathering mineral such as hematites, lamellar silicates, sulphate hydrates and perchlorate. The spectrometers on board the orbiter and the rover as well as the multispectral camera are dedicated to this objective. • 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. • 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. 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, particularly its ionosphere. '''' will also cache rock and soil samples for retrieval by the later sample-return mission, and the orbiter will make it possible to locate a caching site. == Mission planning ==

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 of thrust. The spacecraft's supersonic parachute system had also been successfully tested. 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. == Entering Mars orbit ==

The three -1 spacecraft were 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 down just enough to be captured by Mars's gravitational pull. The orbiter spent several months scanning and imaging the surface of Mars to refine the target landing zone for the lander/rover. It approached at about (periareion, or periapse) to Mars's surface, allowing a high-resolution camera to return images to Earth and to map the landing site in Utopia Planitia, and to prepare for landing. Orbital elements == Landing on Mars ==

Landing area selection The landing area selection was based on two major criteria: • Engineering feasibility, including latitude, altitude, slope, surface condition, rock distribution, local wind speed, visibility requirements during the EDL process. • Scientific objectives, including geology, soil structure and water ice distribution, surface elements, mineral, and rock distribution, magnetic field detection. Three initial areas were selected by the site selection team after a global survey of Mars; the three areas were: Amazonis Planitia, Chryse Planitia, and Utopia Planitia. All three candidate landing areas were between five degrees North and thirty degrees North latitude. According to the site selection team, Amazonis Planitia was dropped from consideration upon further analysis due to the area's small thermal inertias and the possible presence of thick dust in the region; Chryse Planitia was eliminated next due to its rough terrain in terms of elevations, slopes, crater densities, and rock abundances. Finally, a region measuring approximately x in Utopia Planitia and centered on was selected as the primary target for further analysis (a backup target with about the same total area and centered on was also selected at that time.) The landing phase began with the release of the protective capsule containing the lander/rover. The capsule made an atmospheric entry followed by a descent phase under parachute, after which the lander used retro-propulsion to soft-land on Mars. The long delay for the publication of the first images is explained by the short periods of time when the '''' rover and the orbiter are in radio contact and can effectively communicate and transfer data. On 11 June 2021, CNSA released the first batch of scientific images from the surface of Mars including a panoramic image taken by ' and a group photo of ' and the -1 lander taken by the drop camera. The panoramic image is composed of 24 single shots taken by the NaTeCam before the rover was deployed to the Martian surface. The image reveals that the topography and rock abundance near the landing site was consistent with previous anticipations from the scientist on typical south Utopia Planitia features with small but widespread rocks, white wave patterns, and mud volcanoes. == Exploration of Martian surface ==

On 22 May 2021 (02:40 UTC), the '''' rover descended from its lander onto the Martian surface to begin its scientific mission. The first images received on Earth after the rover deployment showed the empty landing platform and the extended rover-descent ramps. On 12 July 2021, Zhurong visited the parachute and backshell dropped onto the Martian surface during its landing on 14 May. On 15 August 2021, Zhurong officially completed its planned exploration tasks and will continue to drive towards the southern part of Utopia Planitia where it landed. On 18 August 2021, Zhurong outlived its lifespan of 90 sols and the Chinese scientists and engineers announced an extended expedition aiming to investigate an ancient coastal area on Mars. From mid-September to late October 2021, both the -1 orbiter and '''' rover entered safe mode due to a communications blackout around solar conjunction. Both devices were back to active mode after the ending of the blackout. On 20 May 2022, Zhurong was put into hibernation mode to prepare for the approaching sandstorms and Martian winter, and was programmed to self-awake at an appropriate temperature and sunlight condition. The rover never awoke from hibernation as of 2025, likely due to dust pile up affecting its solar power generation. On 27 February 2023, the initial results of the meteorological data from the first 325 sols of the mission were published in the journal Nature. == Instruments ==

Scientific instruments To achieve the scientific objectives of the mission, the -1 orbiter is equipped with eight scientific instruments, while the '''' rover is equipped with six, which include: • Mars Orbiter Magnetometer (MOMAG) is used to map Martian magnetic field. • Mars Mineralogical Spectrometer (MMS) utilizes the visible and near infrared imaging spectrometer with detection wavelengths ranging from 0.45 to 3.4 μm to investigate and analyze the Martian surface composition. It also investigate the distribution of regolith types and subsurface structure of Mars. • Mars Orbiter Scientific Investigation Radar (MOSIR) aims to explore the Martian surface and subsurface water-ice by means of the dual-polarization echo characteristics of radar. • Mars Ion and Neutral Particle Analyzer (MINPA) measures the flux of ions in space environment, distinguishes the main ions and obtains their physical parameters such as the density, velocity and temperature. • Mars Energetic Particle Analyzer (MEPA) obtains the energy spectrum, flux and elemental composition of energy electrons, protons, α particles and ions. • Unknown payload, likely the Mars Orbiter Status Monitoring Sensor (MOSMOS), to monitor and evaluate the condition of key components, the Chinese flag and the 2022 Winter Olympics and Paralympics logo on the orbiter. The selfie rod, in weight and long, is made from shape memory composite material, solar heat makes it extended to working position with two cameras fixed at one end and attached to orbiter on another end along with some degrees of freedom to the arm. '''' rover • Mars Rover Penetrating Radar (RoPeR) Ground-penetrating radar (GPR), two frequencies, to image about below the Martian surface It was one of the two very first ground-penetrating radars deployed on Mars, along with the one equipped by NASA's Perseverance rover launched and landed in same years. • Mars Rover Magnetometer (RoMAG) obtains the fine-scale structures of crustal magnetic field based on mobile measurements on the Martian surface. • Mars Climate Station (MCS) (also MMMI Mars Meteorological Measurement Instrument) measures the temperature, pressure, wind velocity and direction of the surface atmosphere, and a microphone to capture Martian sounds. During rover's deployment, it recorded the sound, acting as the second Martian sound instrument to record Martian sounds successfully after Mars 2020 Perseverance rover's microphones. • Mars Surface Compound Detector (MarSCoDe) combines laser-induced breakdown spectroscopy (LIBS) and infrared spectroscopy • Multispectral Camera (MSCam) Combined with MarSCoDe, MSCam investigates the mineral components to establish the relationship between Martian surface water environment and secondary mineral types, and to search for historical environmental conditions for the presence of liquid water. • Navigation and Topography Cameras (NaTeCam) With 2048 × 2048 resolution, NaTeCam is used to construct topography maps, extract parameters such as slope, undulation and roughness, investigate geological structures, and conduct comprehensive analysis on the geological structure of the surface parameters. Lander The lander did not have a scientific payload, but carried a Mars Emergency Beacon designed to survive the force of a catastrophic crash. The beacon would have allowed critical engineering data to be collected to aid future design. The lander also carried the Chinese flag and 2022 Winter Olympics and Paralympics mascots with it like the orbiter. Other instruments • -1 Deployable Cameras, two secondary Payloads deployed in September 2020 in deep space and 31 December 2021 in Mars orbit respectively, that took photos of and tested a radio connection with -1. The photo was released on 11 June 2021, confirming their Martian landing success. ==Other observations==

In 2025 Tianwen-1 used its HiRIC camera to image 3I/ATLAS. == International collaborations ==

Argentina's Comisión Nacional de Actividades Espaciales (CONAE) is collaborating on -1 by way of the Espacio Lejano 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. France's Institut de Recherche en Astrophysique et Planétologie (IRAP) in Toulouse, in France, is collaborating on the '''' rover. of IRAP said: The Austrian Research Promotion Agency (FFG) aided in the development of a magnetometer installed on the -1 orbiter. The Space Research Institute of the Austrian Academy of Sciences in Graz has confirmed the group's contribution to the -1 magnetometer and helped with the calibration of the flight instrument. == See also ==