The primary objective of the mission is to collect and return samples from Mars, with a focus on detecting potential biosignatures to explore whether life ever existed on the planet.

Successful completion of Tianwen-3 could significantly elevate China's status in space exploration and provide crucial insights into the existence of life on Mars.

This mission will enhance China's capabilities in planetary exploration, building on its previous successful lunar sample returns, and aims to investigate Mars' geology, atmosphere, and potential for habitability.

The China National Space Administration (CNSA) issued the invitation for international collaboration on March 13, 2025, amid ongoing challenges faced by NASA, including leadership changes and budget cuts.

Proposals for collaboration must align with Tianwen-3's scientific objectives, which include searching for signs of past life on Mars, and can involve payloads requiring support from the spacecraft or independent instruments.

CNSA is offering 15 kilograms of mass for international projects on the Earth return orbiter and an additional 5 kilograms on the Mars orbiter.

Interested teams must submit expressions of interest by June 30, 2025, with final selection of payloads set for October 2025, and delivery of flight models required by 2027.

The selection process for international projects will be expedited, with letters of intent due by June 2025 and final decisions expected in October 2025.

China's ambitious Tianwen-3 mission to Mars is scheduled for launch in late 2028, aiming to become the first mission to retrieve samples from the planet and inviting international collaboration for scientific projects.

The mission will target three preselected landing sites: Amazonis Planitia, Utopia Planitia, and Chryse Planitia, all chosen for their potential to preserve biosignatures.

Sampling strategies will include surface sampling and drilling, focusing on areas likely to contain preserved organics while adhering to planetary protection measures.

To achieve its goals, Tianwen-3 will utilize advanced scientific instruments, including a Mars Subsurface Penetrating Radar and a Raman and Fluorescence Analyzer, to study the Martian subsurface and search for organic materials.