NEOForCE: Near-Earth Objects’ Forecast of Collisional Events

¹ LTE, Paris Observatory, univ. PSL, Sorbonne univ., univ. Lille, LNE, CNRS, 61 Av. de l’Observatoire, 75014 Paris, France
² Institute of Applied Astronomy, Russian Academy of Sciences, Kutuzova emb. 10, St. Petersburg, Russia

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Received: 11 October 2025
Accepted: 22 January 2026

Abstract

Context. Robust impact monitoring of near-Earth objects is an essential task of planetary defense. Current systems such as NASA’s Sentry-II, NEODyS’s CLOMON2, and ESA’s Aegis have been highly successful, but independent approaches are essential to ensure reliability and to cross-validate predictions of possible impacts, probabilities, and paths on Earth.

Aims. We present NEOForCE (Near-Earth Objects’ Forecast of Collisional Events), a new independent monitoring system for asteroid impact prediction. By relying on orbital solutions from DynAstVO at Paris Observatory and using an original methodology for uncertainty propagation, NEOForCE provides an alternative line of verification for future impact assessments and strengthens the overall robustness of planetary defense.

Methods. As other monitoring systems do, NEOForCE samples several thousand so-called “virtual asteroids” from the uncertainty region and integrates their orbits up to 100 years into the future. Instead of searching for close approaches of the virtual asteroids themselves with the Earth, our system looks for times when the Earth comes close to the “realistic” uncertainty regions around them, which are mostly stretched along the osculating ellipses of virtual asteroids. For every virtual asteroid and every possible collision time, we also estimate the maximal impact probability, and only if this value is large enough (>5 × 10⁻⁸) do we continue to the next step. In this second step, we compute how the original asteroid orbit should be slightly modified so that the new trajectory leads to an Earth impact, which allows us to confirm the possible collision and estimate the impact probability.

Results. We tested NEOForCE against NASA’s Sentry-II system on five representative asteroids with a high impact probability and significant number of possible collisions: 2000 SG344, 2005 QK76, 2008 JL3, 2023 DO, and 2008 EX5. NEOForCE successfully recovered almost all of the possible collisions reported by Sentry-II with impact probabilities above 10⁻⁷, demonstrating the robustness of our approach. In addition, NEOForCE identified several potential impacts at the 10⁻⁷–10⁻⁶ level that Sentry-II did not report.