Dimorphos Orbit Determination from Mutual Events Photometry

0582089 - ASÚ 2025 RIV US eng J - Journal Article
Scheirich, Peter - Pravec, Petr - Meyer, A. J. - Agrusa, H. F. - Richardson, D.C. - Chesley, S.R. - Naidu, S.P. - Thomas, C. - Moskovitz, N. A.
Dimorphos Orbit Determination from Mutual Events Photometry.
The Planetary Science Journal. Roč. 5, č. 1 (2024), č. článku 17. E-ISSN 2632-3338
R&D Projects: GA ČR(CZ) GA20-04431S
Grant - others:GA MŠk(CZ) LM2015042; GA MŠk(CZ) LM2015085
Institutional support: RVO:67985815
Keywords : asteroid dynamics * asteroid satellites * near-Earth objects
OECD category: Astronomy (including astrophysics,space science)
Impact factor: 3.4, year: 2022
Method of publishing: Open access

The NASA Double Asteroid Redirection Test spacecraft successfully impacted the Didymos-Dimorphos binary asteroid system on 2022 September 26 UTC. We provide an update to its preimpact mutual orbit and estimate the postimpact physical and orbital parameters, derived using ground-based photometric observations taken from 2022 July to 2023 February. We found that the total change of the orbital period was33.240 +/- 0.072 minutes (all uncertainties are 3 sigma). We obtained the eccentricity of the postimpact orbit to be 0.028 +/- 0.016 and the apsidal precession rate was 7.3 +/- 2.0 degrees day-1 from the impact to 2022 December 2. The data taken later in 2022 December to 2023 February suggest that the eccentricity dropped close to zero or the orbit became chaotic approximately 70 days after the impact. Most of the period change took place immediately after the impact, but in the few weeks following the impact it was followed by an additional change of27-58+19 s or19 +/- 18 s (the two values depend on the approach we used to describe the evolution of the orbital period after the impact-an exponentially decreasing angular acceleration or the assumption of a constant orbital period, which changed abruptly some time after the impact, respectively). We estimate the preimpact Dimorphos-Didymos size ratio was 0.223 +/- 0.012 and the postimpact is 0.202 +/- 0.018, which indicate a marginally significant reduction of Dimorphos' volume by (9 +/- 9)% as the result of the impact.
Permanent Link: https://hdl.handle.net/11104/0353671