Should We Conduct Rare Event Detection Experiments in Outer Space?

In recent years, human activities in space have surged. Rocket launch costs are being continuously reduced while loading capacities will soon be significantly increased, potentially leading us into a new space era with great opportunities.

In light of these advancements, researchers in quantum technology, astronomy, and accelerator physics are exploring the potential benefits of space experiments. However, discussions on detecting rare events, including dark matter particles, neutrinoless double-beta decay signals, diffusive supernova neutrinos, and neutrinos from a nearby supernova, remain very limited. In this presentation, I will discuss our efforts to investigate various extraterrestrial sites in our solar system via analytical estimates and extensive computer simulations. Surprisingly, we've observed a significant reduction in neutrino and muon backgrounds at some sites, indicating promising prospects for hosting those rare event detection experiments. In addition, as a potential near-term deliverable, we propose to place a small detector inside a lava tube on our Moon to directly detect the so-called prompt component of the cosmic-ray-induced secondary particle production, which has been elusive in terrestrial experiments but should be easily detectable at the proposed site.