Directional Scientific Objectives of the Interstellar Express Mission

This paper briefly introduces the main scientific objectives, observational requirements, and expected scientific returns of boundary exploration missions in different directions, such as the heliospheric nose and tail; reviews the current research status at home and abroad, including ongoing and proposed missions and their scientific payload configurations; and summarizes several major scientific questions related to heliospheric physics, the interstellar medium, and solar system evolution in different directions, finally presenting prospects for China’s future scientific development in independent boundary exploration.