Tianwen-1
-1 is an interplanetary mission by the China National Space Administration which sent a robotic spacecraft to Mars, consisting of six spacecraft: an orbiter, two deployable cameras, lander, remote camera, and the ' rover. The spacecraft, with a total mass of nearly five tons, is one of the heaviest probes launched to Mars and carries 14 scientific instruments. It is the first in a series of planned missions undertaken by CNSA as part of its Planetary Exploration of China program.
The mission's scientific objectives include: investigation of Martian surface geology and internal structure, search for indications of current and past presence of water, and characterization of the space environment and the atmosphere of Mars.
The mission was launched from the Wenchang Spacecraft Launch Site on 23 July 2020 on a Long March 5 heavy-lift launch vehicle. After seven months of transit through the inner Solar System, the spacecraft entered Martian orbit on 10 February 2021. For the next three months the probe studied the target landing sites from a reconnaissance orbit. On 14 May 2021, the lander/rover portion of the mission successfully touched down on Mars, making China the third nation to make a soft landing on and establish communication from the Martian surface, after the Soviet Union and the United States.
On 22 May 2021, the ' rover drove onto the Martian surface via the descent ramps on its landing platform. With the successful deployment of the rover, China became the second nation to accomplish this feat, after the United States. In addition, China is the second nation to orbit and the first one to carry out landing and rovering mission on Mars successfully on its maiden attempt. -1 is also the second mission to capture audio recordings on the Martian surface, after United States' Perseverance rover. The "smallsat" deployed by the rover on the Martian surface consists of a "drop camera" which photographed both the rover itself as well as the -1 lander. With a mass of less than 1 kg, the -1 remote camera is the lightest artificial object on Mars as of May 2021. On December 31, 2021, the -1 orbiter deployed a second deployable camera into Mars orbit which captured photographs of the -1 in orbit to celebrate its achievement of the year and a selfie stick payload was deployed to its working position on orbiter to take images of the orbiter's components and Chinese flag on 30 January 2022 to celebrate the Chinese New Year. In September 2022, the mission was awarded the World Space Award by the International Astronautical Federation.
The -1 mission was the second of three Martian exploration missions launched during the July 2020 window, after the United Arab Emirates Space Agency's Hope orbiter, and before NASA's Mars 2020 mission, which landed the Perseverance rover with the attached Ingenuity helicopter drone. The Zhurong rover lost contact in 2023 after failing to awake from a scheduled hibernation.
Nomenclature
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. 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. 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
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 and is managed by the National Space Science Centre 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, a small satellite with two cameras that took photos of and tested a radio connection with -1. Its mission was to photograph the -1 orbiter and the lander's heat shield. Due to the time when it was deployed, it trajectory predicted to do a flyby of Mars with that happening around the orbit insertion date.
During its cruise to Mars, the spacecraft completed four trajectory correction maneuvers plus an additional maneuver to alter its heliocentric orbital inclination; it also performed self diagnostics on multiple payloads. 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 safely touched down in the Utopia Planitia region on Mars. After a period spent conducting system checkouts and other planning activities, the lander deployed the rover for independent surface operations. This rover is powered by solar panels and will probe the Martian surface with radar and conduct chemical analyses on the soil; it will also look 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 mission also serves as a technology demonstration that will be needed for an anticipated Mars sample-return mission proposed for the 2030s. 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.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, the 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.
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 was chosen for being both of scientific interest and being safe enough for landing attempts. Simulated landings have been performed as part of mission preparations by the Beijing Institute of Space Mechanics and Electricity.
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.