China's Tianwen-3 will be the country's first Mars sample return mission, scheduled to launch in 2028 with samples returning in 2031. A team from the Department of Earth and Planetary Sciences in the HKU Faculty of Science has been selected to build one of its instruments, a short-wavelength infrared spectrometer, working with major collaborators at Zhejiang University and the Chinese Academy of Sciences Changchun Institute of Optics, Fine Mechanics and Physics.
The instrument will be mounted on the spacecraft's service module and has a layered set of objectives. Using hyperspectral imaging it will provide high-spatial-resolution mineralogical maps of candidate landing sites, monitor the development of dust storms to help the lander touch down safely, search for biosignatures and hydrous minerals, and survey Martian resources. Landing-site characterisation and operational weather monitoring are not usually combined in one instrument.
Its working life extends well past the sampling phase. After sample return the spectrometer is expected to continue operating in orbit for at least five years, observing the low-latitude regions of Mars. That gives the instrument a dual character: mission-critical support hardware during descent and landing, then a long-duration science platform once the primary objective is complete.
The HKU group leading the project has also contributed to the mission's landing site selection team and its science team, so the instrument is being built by people shaping where it will look. For Hong Kong the selection extends a growing role in China's deep-space programme, and for planetary scientists internationally it adds another orbital hyperspectral dataset over terrain that will, uniquely, have returned samples to Earth.