Completed · full success Lander 2020

Tianwen-1 (Lander)

The CNSA's Tianwen-1 mission marked China's first successful landing on the Martian surface with a lander and the Zhurong rover in Utopia Planitia. After exceeding its designed lifespan and completing its scientific objectives on geology and the subsurface, the primary surface mission concluded successfully.

Part of the missionZhurong
Tianwen-1 (Orbiter)OrbiterZhurong (Rover)Rover
Agency CNSA
Launch SOL 29 OF MANGALO OF YEAR 35 · 09:57 MTC
Arrival at Mars SOL 20 OF CHRYSIO OF YEAR 36 · 07:37 MTC
Operations Start SOL 27 OF CHRYSIO OF YEAR 36 · 14:30 MTC
Mission End SOL 28 OF LUNO OF YEAR 36 · 09:37 MTC
of travel 295 days · ~287 sols
of operations 334 sols · 344 days
Cruise to Mars296 days
Arrival & commissioning7 days
Operations344 days

Trajectory to Mars

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Technical Analysis of the Tianwen-1 Mission (Zhurong Lander and Rover)

  • Mission Designation: Tianwen-1 (TW-1)
  • COSPAR Designation: 2020-049A
  • Operating Agency: China National Space Administration (CNSA)
  • Launch Date: July 23, 2020 04:41 UTC
  • Landing Date: May 15, 2021 00:18 UTC
  • Landing Site: Utopia Planitia, Mars (Latitude 25.102° N, Longitude 109.914° E)
  • Launch Vehicle: Long March 5 Rocket (Y4)
  • Launch Site: Wenchang Spacecraft Launch Site, Pad LC-101
  • Mission Status: Mission Accomplished (Surface segment completed)

1. Mission Objectives

Tianwen-1 represented the People's Republic of China's first comprehensive foray into the in situ exploration of the planet Mars. The primary objectives of the surface segment focused on:

  • Investigating the morphology and geological structure of the Martian surface in the Utopia Planitia region.
  • Characterizing the physical properties of the soil and determining the potential distribution of water ice.
  • Analyzing the elemental and mineralogical composition of surface materials.
  • Studying the climate, meteorology, and local atmospheric environment.
  • Exploring the internal structure and physical field properties of the planet using geophysical instrumentation.

2. Probe Specifications and Subsystems

The complete Tianwen-1 probe assembly had a nominal launch mass of 5000 kg, integrating the orbiter, lander, and rover. The lander, with a mass of 1060 kg, housed the Zhurong rover inside. The latter had a mass of 240 kg and approximate dimensions of 2.6 m × 3 m × 1.85 m.

Zhurong's power supply system was based on four-wing folding solar panels, optimized with phase change materials to mitigate the thermal impact of low Martian night temperatures. Communications with Earth were established via direct link or by using the orbiter as a data relay. Vehicle mobility was entrusted to an independent six-wheel running gear, complemented by a ramp mechanism to ensure a safe descent from the lander body to the Martian regolith.

3. Payload and Scientific Instrumentation

The surface segment carried a diversified set of scientific instruments distributed between the lander and the Zhurong rover:

  • NaTeCam (Navigation and Terrain Camera): Navigation and terrain camera intended for the acquisition of high-resolution topographic images for trajectory planning.
  • MSCam (Multispectral Camera): Multispectral instrument for detailed mineralogical characterization of rock outcrops and regolith.
  • RoSPR (Rover-mounted Subsurface Penetrating Radar): Subsurface penetrating radar to explore stratigraphy and the presence of shallow ice structures.
  • MarSCoDe (Mars Surface Composition Detector): Spectrometer based on the laser-induced breakdown technique to determine the elemental chemical composition of rocks.
  • RoMAG (Mars Rover Magnetometer): Magnetometer intended for measuring the local magnetic field of the Martian crust.
  • MCS (Mars Climate Station): Meteorological station for the continuous recording of parameters such as temperature, ambient pressure, wind speed, and direction.

4. Launch Vehicle and Trajectory

The launch was executed on July 23, 2020, at 04:41:15 UTC by a Long March 5 (Y4) heavy launcher from pad LC-101 of the Wenchang Spacecraft Launch Site. After completing the interplanetary transfer trajectory, Mars orbit insertion materialized on February 10, 2021. The critical surface arrival milestone took place on May 15, 2021, at 00:18 UTC, when the lander successfully employed a combined sequence of heat shield, supersonic parachute, and variable-thrust retrorockets to land in Utopia Planitia. The final deployment of the Zhurong rover onto the surface was completed on May 22, 2021.

5. Results and Discoveries

Operations in Utopia Planitia confirmed the existence of geomorphological features associated with the historical presence of water and underground ice accumulations. Data provided by the subsurface radars (RoSPR) and spectrometers (MarSCoDe) revealed a complex stratigraphy in the shallow subsurface, characterized by sedimentary layers and indications of past aeolian and aqueous activity. Likewise, the meteorological station (MCS) recorded a valuable time series on the dynamics of the Martian atmospheric boundary layer.

6. Legacy and Importance of the Mission

The primary mission officially concluded on May 1, 2022, after comfortably meeting its primary objectives and exceeding 90 sols of designed lifespan. Although the Zhurong rover entered a hibernation phase due to dust accumulation and the Martian winter without subsequently managing to reactivate, the technological and scientific success of the landing consolidated the CNSA in planetary in situ exploration, while the orbital component continued to operate independently.

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