Fuente Marcos, Raúl de laLeon, J. deFuente Marcos, Carlos de laLicandro Goldaracena, JavierSerra-Ricart, M.Cabrera-Lavers, A.2023-06-222023-06-222023-02-020004-636110.1051/0004-6361/202245514https://hdl.handle.net/20.500.14352/72888Reseñado en: Sacristán, Enrique. Una miniluna acompañará a la tierra durante las próximas décadas. Retrieved Feb 13, 2023, from https://www.agenciasinc.es/Noticias/Una-miniluna-acompanara-a-la-Tierra-durante-las-proximas-decadasContext. The near-Earth orbital space is shared by natural objects and space debris that can be temporarily captured in geocentric orbits. Short-term natural satellites are often called mini-moons. Reflectance spectroscopy can determine the true nature of transient satellites because the spectral signatures of spacecraft materials and near-Earth asteroids (NEAs) are different. The recently discovered object 2022 NX1 follows an Earth-like orbit that turns it into a recurrent but ephemeral Earth companion. It has been suggested that 2022 NX1 could have an artificial origin or be lunar ejecta. Aims. Here, we use reflectance spectroscopy and N-body simulations to determine the nature and actual origin of 2022 NX1. Methods. We carried out an observational study of 2022 NX1, using the OSIRIS camera spectrograph at the 10.4 m Gran Telescopio Canarias, to derive its spectral class. N-body simulations were also performed to investigate how it reached NEA space. Results. The reflectance spectrum of 2022 NX1 is neither compatible with an artificial origin nor lunar ejecta; it is also different from the V type of the only other mini-moon with available spectroscopy, 2020 CD3. The visible spectrum of 2022 NX1 is consistent with that of a K-type asteroid, although it could also be classified as an Xk type. Considering typical values of the similar albedo of both K-type and Xk-type asteroids and its absolute magnitude, 2022 NX1 may have a size range of 5 to 15 m. We confirm that 2022 NX1 inhabits the rim of Earth’s co-orbital space, the 1:1 mean-motion resonance, and experiences recurrent co-orbital engagements of the horseshoe-type and mini-moon events. Conclusions. The discovery of 2022 NX1 confirms that mini-moons can be larger than a few meters and also that they belong to a heterogeneous population in terms of surface composition.engAtribución 3.0 Españahttps://creativecommons.org/licenses/by/3.0/es/journal articlehttps://doi.org/10.1051/0004-6361%2F202245514https://www.aanda.org/articles/aa/full_html/2023/02/aa45514-22/aa45514-22.htmlopen access51-33Minor planetsAsteroidsGeneralIndividual2022 NX1TechniquesSpectroscopicMethodsNumericalCelestial mechanicsAstrofísica