Energy dissipation in synchronous binary asteroids

Meyer, Alex J.; Scheeres, Daniel J.; Agrusa, Harrison F.; Noiset, Guillaume; McMahon, Jay W.; Karatekin, Özgür; Hirabayashi, Masatoshi; Nakano, Ryota

doi:10.1016/j.icarus.2022.115323

Cited by 12 publications

(14 citation statements)

References 55 publications

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“…So, depending on the possible libration angle at the time of impact, one might be fooled into thinking Dimorphos was more or less oblate than it actually is. Because no libration has been directly detected by preimpact observations (Pravec et al 2022;Scheirich & Pravec 2022), the forced component would be small in amplitude (Section 2.3.1), and the free component would be dampened over a short timescale (Meyer et al 2023b), we conclude that the terminator assessments reported here are reasonable.…”

Section: The Extent Of the B Axis: The Draco Perspectivementioning

confidence: 67%

“…In that case, the forced libration would be <1°. While we cannot definitively rule out that some unknown event caused Dimorphos to have a large preimpact free libration amplitude, we consider this to be unlikely due to the relatively rapid dissipation timescale for free libration (Meyer et al 2023b) and the lack of any obvious excitation mechanisms. We therefore posit that Dimorphos was probably not librating at the time of impact to a degree that would substantially change the result of the terminator assessments.…”

Section: Notementioning

confidence: 91%

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An Updated Shape Model of Dimorphos from DART Data

Daly,

Ernst,

Barnouin

et al. 2024

Planet. Sci. J.

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Dimorphos was the target of the Double Asteroid Redirection Test (DART) mission. This paper summarizes the properties of an updated shape model of Dimorphos, describes the differences between the updated shape model and an earlier version published by Daly, Ernst, Barnouin et al. (doi:10.1038/s41586-023-05810-5), summarizes the data products associated with this model, and explains where the products can be accessed. The updated shape model benefited from improved methods of incorporating limb information, which will accelerate future shape modeling efforts for other objects with limited imaging data. The updated shape model is similar to the earlier model but slightly smaller (−2.8% change in volume) than the previous Dimorphos global shape model, and the updated shape is slightly more elongated. The additional analysis reported here supports an oblate preimpact shape for Dimorphos. This result indicates that the postimpact elongation of Dimorphos derived from ground-based observations is evidence for a large crater or global reshaping of the asteroid due to the DART impact. The updated global shape model of Dimorphos, as well as the earlier version, will be available in the Planetary Data System Small Bodies Node and through the public Small Body Mapping Tool.

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Section: The Extent Of the B Axis: The Draco Perspectivementioning

confidence: 67%

Section: Notementioning

confidence: 91%

An Updated Shape Model of Dimorphos from DART Data

Daly,

Ernst,

Barnouin

et al. 2024

Planet. Sci. J.

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“…Furthermore, radar images constrain Dimorphos’s spin period to be within 3 h of the synchronous rate 35 . Recent models for tidal dissipation in binary asteroids suggest that any free libration would dissipate on 100-year timescales 43 , making any substantial free libration unlikely given the timescales for excitation mechanisms such as close planetary encounters and natural impacts 10 . Furthermore, Dimorphos’s pre-impact eccentricity is constrained to be less than 0.03 (refs.…”

Section: Methodsmentioning

confidence: 99%

Momentum transfer from the DART mission kinetic impact on asteroid Dimorphos

Cheng

Agrusa

Barbee

et al. 2023

Nature

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The NASA Double Asteroid Redirection Test (DART) mission performed a kinetic impact on asteroid Dimorphos, the satellite of the binary asteroid (65803) Didymos, at 23:14 UTC on 26 September 2022 as a planetary defence test1. DART was the first hypervelocity impact experiment on an asteroid at size and velocity scales relevant to planetary defence, intended to validate kinetic impact as a means of asteroid deflection. Here we report a determination of the momentum transferred to an asteroid by kinetic impact. On the basis of the change in the binary orbit period2, we find an instantaneous reduction in Dimorphos’s along-track orbital velocity component of 2.70 ± 0.10 mm s−1, indicating enhanced momentum transfer due to recoil from ejecta streams produced by the impact3,4. For a Dimorphos bulk density range of 1,500 to 3,300 kg m−3, we find that the expected value of the momentum enhancement factor, β, ranges between 2.2 and 4.9, depending on the mass of Dimorphos. If Dimorphos and Didymos are assumed to have equal densities of 2,400 kg m−3, $${\beta =3.61}_{-0.25}^{+0.19}(1\sigma )$$ β = 3.61 − 0.25 + 0.19 ( 1 σ ) . These β values indicate that substantially more momentum was transferred to Dimorphos from the escaping impact ejecta than was incident with DART. Therefore, the DART kinetic impact was highly effective in deflecting the asteroid Dimorphos.

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“…By measuring the post-impact observable semimajor axis, the pre-impact observable semimajor axis can be inferred, leading to a much narrower estimate of Δv T . However, this may become more complicated if secular effects have noticeably evolved the semimajor axis in the time between the impact and Hera's arrival (Meyer et al 2023). No close encounters that could perturb the Didymos mutual orbit further are expected with any of the terrestrial planets for thousands of years, using the semi-analytical propagation of the heliocentric orbit from Fuentes-Muñoz et al (2022).…”

Section: » -+mentioning

confidence: 99%

The Perturbed Full Two-body Problem: Application to Post-DART Didymos

et al. 2023

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With the successful impact of the NASA Double Asteroid Redirection Test (DART) spacecraft in the Didymos–Dimorphos binary asteroid system, we provide an initial analysis of the post-impact perturbed binary asteroid dynamics. To compare our simulation results with observations, we introduce a set of “observable elements” calculated using only the physical separation of the binary asteroid, rather than traditional Keplerian elements. Using numerical methods that treat the fully spin–orbit-coupled dynamics, we estimate the system’s mass and the impact-induced changes in orbital velocity, semimajor axis, and eccentricity. We find that the changes to the mutual orbit depend strongly on the separation distance between Didymos and Dimorphos at the time of impact. If Dimorphos enters a tumbling state after the impact, this may be observable through changes in the system’s eccentricity and orbit period. We also find that any DART-induced reshaping of Dimorphos would generally reduce the required change in orbital velocity to achieve the measured post-impact orbit period, and will be assessed by the ESA Hera mission in 2027.

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Energy dissipation in synchronous binary asteroids

Cited by 12 publications

References 55 publications

An Updated Shape Model of Dimorphos from DART Data

An Updated Shape Model of Dimorphos from DART Data

Momentum transfer from the DART mission kinetic impact on asteroid Dimorphos

The Perturbed Full Two-body Problem: Application to Post-DART Didymos

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