BEIJING -- China's mission to retrieve samples from Mars will advance to the flight model development phase within this year, Liu Jizhong, chief designer of the Tianwen 3 mission, said on Thursday.

Building on the preliminary technical research and demonstrations, the mission has achieved breakthroughs in key technologies. The engineering team is now focused on developing prototypes, Liu, also a national legislator, told reporters.

The Mars sample return mission is scheduled for launch around 2028, with the goal of returning no less than 500 grams of Martian samples to Earth by around 2031.

International scientists are invited to collaborate in advancing deep space exploration technology development and engineering, according to Liu.

In terms of engineering, the mission is developing an orbiter, a returner, a lander, an ascender, and a service module, which will compose the orbiter-returner complex and the lander-ascender-service module complex.

The development work also includes achieving breakthroughs in key technologies such as Martian surface sampling and sealing, Martian surface takeoff and ascent, Mars orbital rendezvous, sample capture and transfer, and planetary protection.

The mission is expected to search for potential signs of life on Mars, investigate Martian geological formation, and examine Martian atmosphere, with the objective of making major discoveries in the study of habitable evolution of terrestrial planets.

"The Tianwen 3 mission represents a highly challenging, innovative and pioneering major space endeavor," said Liu. "It is expected to achieve humanity's first Mars sample return mission, thus significantly advancing the integrated development of space science, space technology and space applications."

Liu also noted that China's Tianwen 2 probe, launched in 2025, has traveled approximately 700 million kilometers and will reach the near-Earth asteroid 2016HO3 this year to begin flying around it for exploration.