ESA says that as of November 2024 humanity knew of more than 1,200,000 asteroids, including over 36,000 near-Earth objects, and around 1,700 of those were on ESA’s risk list because they merit close follow-up observations[1]. ESA’s risk list is built from objects with a non-zero computed Earth-impact probability and is updated through the Near-Earth Object Coordination Centre, which computes impact probabilities over the next 100 years[2]. ESA also states that its planetary-defence work is part of the Space Safety programme and includes regular sky surveys, orbit prediction, and impact warnings[3].
For the Lunar Ark, the operational lesson is that existential-risk monitoring must be continuous, quantitative, and long-horizon: a 100-year prediction window is useful for near-term defense, but a 1,000-year civilisation archive needs permanent cross-generational orbit records, uncertainty tracking, and re-analysis capability as observations improve[2][3]. The key technical issue is not the raw count of objects, but the pipeline that converts sparse measurements into ranked risk, because that same architecture can be reused for other planetary-scale hazards such as comets, radiation events, or orbital debris cascades. ESA’s public risk infrastructure shows that a stable catalogue plus repeated observation can collapse uncertainty over time, which is the exact preservation logic the Ark should embed in its own hazard registry[2].
The Ark team should preserve the ESA model: maintain a continuously updated threat ledger, store raw observations and orbit solutions, preserve the ranking logic behind each risk entry, and keep named institutional procedures for follow-up rather than only final conclusions. The most important integration is an autonomous triage system that can flag any object with non-zero impact probability, preserve the full decision chain, and trigger multi-epoch review at fixed intervals. The Ark should also track ESA’s Space Safety programme, NEO Coordination Centre, and any future improvements to survey capability because they represent the state of the art in long-horizon planetary warning[2][3].