HEFEI -- China is planning to promote its space science development on five major themes, including research on habitable planets, and biological and physical sciences in space, a senior Chinese space expert said Tuesday.

China is making a national plan suggesting the deployment of more scientific satellites in the country's space program to yield leading breakthroughs globally on themes such as the extreme universe, space-time ripple, Sun-Earth panorama, habitable planets, and biological and physical sciences in space, said Wang Chi, director of the National Space Science Centre under the Chinese Academy of Sciences.

Wang made the remarks in his a speech delivered at the International Deep Space Exploration Conference held on Tuesday and Wednesday in Hefei, capital of East China's Anhui province.

According to Wang, the National Space Science Plan, which is currently under evaluation, is the first long-term national plan of China's space science program, with a time range spanning from 2023 to 2045.

Under the five themes, there are 17 top scientific priorities, including dark matter and physics in extreme conditions, the origin and evolution of the universe, and the hot universe baryon survey by X-ray explorers. These three scientific priorities can support the study of the extreme universe.

The space-time ripple refers to exploring the wrinkle of space-time through a space-borne gravitational wave observatory, Wang said in his speech.

The Sun-Earth panorama theme covers outer solar system exploration, solar observation, space weather observation in the solar system, comprehensive exploration of Earth-Moon space, and Earth system observatory.

The habitable planet theme includes research on Earth, icy moons in the solar system and exoplanets, such as frontier issues of searching for alien life beyond Earth and detection, as well as characterization and imaging of exoplanets.

The theme of biological and physical sciences in space covers micro-gravity science, quantum experiments, and the origin and adaptation of life in space, with China's space station as the main platform.

Wang said the selection of future missions will be based on the scientific significance, technical feasibility and economical affordability, adding that international collaboration is strongly encouraged at all levels in those missions.