Ground Verification Test for Tianwen-2 Payloads

China's Tianwen-2 exploration mission is designed to perform comprehensive remote sensing, in-situ exploration, and sample return from the target small celestial bodies (2016HO3 and the main-belt comet 311P) through a series of operations including flyby, orbiting, landing, and sample collection. The mission will further investigate the formation and evolution of these target celestial bodies, their orbital dynamics, as well as correlations between the returned samples, meteorites, and data obtained from ground-based and remote sensing observations. Prior to the launch of the Tianwen-2 mission, we carried out comprehensive ground-based test to verify the detection capabilities of its nine onboard payloads and to assess the accuracy of the data they are designed to acquire. 

Results show that all payloads have met the predetermined test objectives, demonstrating robust detection performance and reliable data validity. The images obtained by the Asteroid Medium Angle Camera and Narrow Angle Camera deliver images with a modulation transfer function (MTF) ≥ 0.2, capable of providing high‑quality imagery for morphological studies. The Asteroid Laser Detection and Ranging achieves a measurement accuracy better than 3cm, enabling precise acquisition of three-dimensional topographic data of the asteroid surface. Spectral data obtained by the Asteroid Multispectral Camera, Visible and Infrared Imaging Spectrometer, and Thermal Emission Spectrometer show good agreement with reference measurements from standard instruments, confirming their capability to identify various minerals. The Dust Multi-properties Analyzer module of the Asteroid Dust and Volatiles Analyzer successfully measures dust‑particle size, morphology, velocity, and mass. The Volatiles Ion Trap Analyzer module of the Asteroid Dust and Volatiles Analyzer can detect no fewer than 14 gas species, with concentration measurement accuracy better than 33%. Using a dual‑probe gradient magnetic‑field measurement method, the Asteroid Magnetometer effectively suppress spacecraft magnetic interference and acquired valid magnetic-field information of the detection target. The Asteroid CoreScan Radar can achieve penetration depths of 35m and 5m for its low-frequency and high-frequency channels, respectively.