The Launch of SELENE

On 14 September 2007, the Japanese space programme achieved a significant milestone in lunar exploration with the successful launch of the SELENE spacecraft. Widely recognised by its project name, Kaguya, this mission represented a major investment in planetary science and signalled Japan’s growing capability to conduct complex, long-term orbital research. By sending a sophisticated orbiter to the Moon, the mission aimed to deepen the international scientific community's understanding of our nearest celestial neighbour, moving beyond the initial reconnaissance of the mid-twentieth century to a more detailed, systematic analysis.

The primary objectives of the Kaguya mission were rooted in a desire to reconstruct the Moon's complex history. Scientists sought to uncover the specific processes behind the Moon's origin and evolution, examining how the lunar body formed and changed over billions of years. To achieve this, the spacecraft was equipped with a suite of instruments designed to gather high-fidelity data that would provide a clearer picture of the geological and chemical shifts that have shaped the lunar landscape since its inception.

Mapping the Lunar Environment

Beyond its historical investigations, Kaguya was tasked with performing a rigorous survey of the contemporary lunar environment. The orbiter focused heavily on mapping the gravity field of the Moon, which is essential for understanding its internal structure and mass distribution. By tracking subtle variations in the spacecraft’s orbit, researchers could infer the density and composition of the lunar crust and mantle, offering insights into the Moon’s interior that were previously inaccessible to ground-based observation.

The mission also prioritised the study of the lunar surface environment, including the interaction between the Moon and the space environment surrounding it. This involved assessing surface composition and the various phenomena that affect the lunar exterior, such as radiation and particle bombardment. These measurements were vital for building a comprehensive model of the Moon as an active, dynamic environment rather than a static, unchanging rock, thereby providing a foundation for future lunar science and potential exploration efforts.

The Kaguya mission stands as one of the most important planetary science endeavours undertaken by Japan, providing a wealth of data that continues to inform our understanding of the Moon's geological development and its place within the solar system.

The success of the Kaguya mission cemented Japan's role as a key contributor to the Modern Lunar Return era. By executing such a multifaceted mission, the programme demonstrated the technical precision required to operate in deep space and maintain a stable orbit around another world for an extended period. The data returned by Kaguya has become a cornerstone of lunar research, ensuring that the mission remains a landmark achievement in the history of space exploration and a testament to the value of dedicated, long-term orbital observation.