Letter to the Editor

Shape and spin axis determination of the Tianwen-2 target asteroid (469219) Kamo’oalewa from light-curve inversion

¹ BSA Osservatorio (K76), Strada Collarelle 53, 12038 Savigliano, Cuneo, Italy
² Charles University, Faculty of Mathematics and Physics, Institute of Astronomy, V Holešovičkách 2, 18000 Prague, Czech Republic
³ Laboratoire Lagrange, Centre National de la Recherche Scientifique, Observatoire de la Côte d’Azur, Université Côte d’Azur, 06304 Nice, France
⁴ University of Leicester, School of Physics and Astronomy, University Road, LE1 7RH, Leicester, UK

^★ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 18 March 2026
Accepted: 29 April 2026

Abstract

Context. Near-Earth asteroid (469219) Kamo’oalewa is an Earth quasi-satellite, temporarily trapped in a 1:1 orbital resonance with our planet. Despite its dynamical relevance and the hypothesis that it may be a lunar ejecta fragment, its physical properties are still poorly constrained. In particular, no reliable models of its shape and spin state have been published so far. The scientific interest in this object is further enhanced by its selection as the primary target of the Chinese Tianwen-2 mission, which aims to meet with this asteroid and return samples of it to Earth.

Aims. The aim of this work is to determine the shape and spin axis orientation of Kamo’oalewa by means of photometric telescope observations and light-curve inversion.

Methods. We analysed light curves obtained during several apparitions using the well-established algorithm, based on convex shape modelling.

Results. We derived a convex shape model and estimated the spin pole orientation. In the preferred solution, the pole is located at ecliptic coordinates λ, β = (126, −16)°, with a sidereal rotation period of P = 0.465 h.

Conclusions. Our results provide the first direct constraints on the rotational state and morphology of Kamo’oalewa, which is information of key importance in preparation for the upcoming Tianwen-2 sample-return mission.