Risks of debris between the Earth and the moon for future exploration

A new study highlights the growing risks posed by debris in cislunar space, particularly in distant retrograde orbits (DROs), as nations and private companies prepare for increased human and robotic activity around the moon. Researchers from the Chinese Academy of Sciences (CAS) have published findings suggesting that debris generated from collisions in these orbits could pose a serious threat to future lunar missions. As plans for sustained human presence on the moon intensify, understanding and mitigating such risks becomes increasingly urgent. The surge in lunar missions reflects a global shift toward deep-space exploration. Over the past few years, numerous countries and organizations have launched spacecraft to the moon, including China’s Longjiang-2 orbiter and the Chang’e program, India’s Chandrayaan-2 and -3 orbiters, South Korea’s Danuri orbiter, Israel’s Beresheet lander, and Japan’s Hakuto-R Mission 1. NASA’s Artemis program, with its uncrewed Artemis I test flight and upcoming crewed Artemis II mission, marks another major milestone. Additionally, the CAPSTONE mission, launched in June 2022, successfully entered a near-rectilinear halo orbit around the moon, demonstrating key technologies for future lunar operations. By 2030, both NASA and China aim to send astronauts and taikonauts to the lunar surface, setting the stage for the establishment of permanent bases and infrastructure. These efforts are part of broader initiatives such as the International Lunar Research Station (ILRS), a joint project involving China and Russia, and the European Space Agency’s Argonaut program. The increasing number of missions underscores the need for robust safety protocols, especially given the potential hazards of debris in cislunar space. One of the primary concerns is the accumulation of debris in orbits critical for lunar operations. The presence of debris can increase the likelihood of collisions, which in turn can trigger chain reactions known as the Kessler effect. This phenomenon, well documented in low Earth orbit (LEO), occurs when the density of space debris becomes so high that collisions generate more debris, leading to a cascading effect that threatens satellites, spacecraft, and even space stations. Similar dynamics may emerge in cislunar space as the volume of human and robotic activity grows. To assess these risks, the CAS research team modeled the behavior of debris clouds resulting from potential collisions in DROs. They used the Circular Restricted Three-Body Problem (CR3BP) model to establish baseline orbital parameters and applied the NASA Standard Breakup Model to simulate how debris might fragment at different points along three DROs. To track the spread of debris over time, they employed the Bicircular Restricted Four-Body Problem (BCR4BP) model, simulating debris movement over a 30-day period. Their analysis revealed that while the overall percentage of debris fragments remaining in orbit after 30 days would stay below 3.5%, the distribution and trajectory of these fragments could still pose challenges. The study emphasizes the importance of monitoring debris patterns and developing predictive models to ensure the safety of future lunar missions. With more missions scheduled to launch in the coming years, the need for comprehensive debris management strategies has never been greater.