3D Radiative-transfer Simulations of the Ejecta Plume Anticipated from DART Impact

Kolokolova, Ludmilla; Li, Jian‐Yang; Selous, Mark van; Farnham, T. L.; Nagdimunov, Lev

doi:10.3847/psj/ac9cde

“…We note that the apex of the ejecta cone is located close to the center of Dimorphos (within 15 m), in contrast to the estimates and simulations of LICIACube observations implemented prior to the impact event Kolokolova et al 2022). The fact that the apex is located much closer to the center than the surface implies that the crater generated by the impact may have been in a gravity-dominated regime as opposed to a strength-dominated regime, which could be preferred prior to the impact owing to an S-type taxonomic composition linked with L/LL meteorites.…”

Section: Discussioncontrasting

confidence: 56%

Characterization of the DART Impact Ejecta Plume on Dimorphos from LICIACube Observations

Deshapriya,

Hasselmann,

Gai

et al. 2023

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We modeled the geometry and the three-dimensional orientation of the ejecta cone triggered by the impact of the DART spacecraft on the asteroid Dimorphos. We used eight LUKE images of the impact acquired by the CubeSat LICIACube that flew by the Didymos system shortly after the impact. These images, which show the ejecta cone in both face-on and side-on profiles, enabled us to reconstruct the ejecta cone in inertial space. We started our model as a simple cone with a circular base and developed it to a rotated cone with an elliptical base that best fit the data. The cone axis points to R.A., decl. (in J2000): 147 − 10 ° + 1 ° , + 16 − 6 ° + 4 ° . The cone is characterized by two perpendicular half-angles of η = 69 − 3 ° + 1 ° , γ = 51 − 11 ° + 1 ° and a rotation of ω = 12° around its axis. The apex of the cone is located near the center of Dimorphos within 15 m. The intersection of the cone and the surface of Dimorphos (surface enclosed by the cone) would correspond to a crater with a maximum radius of about 65 m. The characterization of the cone axis is directly related to the computation of the momentum enhancement factor (β) of the impact, and it hence proves the crucial need of studying impacts in the context of planetary defence scenarios. The results of this work could potentially be used to constrain whether the impact took place in a strength-dominated or a gravity-dominated regime. This work shows the important scientific return of the LICIACube CubeSat in the context of planetary defence.

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“…We computed brightness simulations from the perspective of LICIACube at three representative time steps during its flyby: observing from in front of the plume, from the side, and from behind. As previously stated, the focus of this study has been to plume brightness from the LICIACube perspective using realistic scattering properties, not to model DART plume evolution, which is the intent of ongoing studies by Cheng et al (2022, Kolokolova et al (2022), and others.…”

Section: Discussionmentioning

confidence: 99%

Optical Characterization of the DART Impact Plume: Importance of Realistic Ejecta Scattering Properties

Lolachi

¹

,

Glenar

²

,

Stubbs

³

et al. 2023

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The Double Asteroid Redirection Test (DART) mission will impact the moon Dimorphos of the (65803) Didymos binary and demonstrate the kinetic impactor technique for planetary defense. Observations from the ride-along CubeSat companion, LICIACube, of the spatial structure and temporal evolution of the resulting ejecta plume will help determine the vector momentum transfer and constrain physical properties such as strength and porosity. The optical scattering properties of the ejecta particles used in plume simulations will dictate the critical relation between observed brightness and inferred ejecta mass (and momentum). Here we examine the scattering behavior of plausible analogs for Dimorphos ejecta particles, including laboratory-measured “millimeter grains” selected based on a comparison with Bennu particle photometry. Over the range of phase angles observable by LICIACube (≲120°), brightness simulations for optical depths ranging from 0.01 to 10 show that scattering from these analogs is considerably dimmer than from grains scattering isotropically. Therefore, adopting realistic scattering properties for ejecta particles is critical for accurately interpreting and understanding observations of the DART impact.

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“…As determined by mapping >90 ∼meter-sized boulders, the distribution of the boulders that can be tracked in the LICIACube images shows clustering in an ejection direction nearly perpendicular to DARTʼs incoming trajectory, in the direction of Dimorphos' south pole, with a speed of tens of meters per second (Farnham et al 2023). Efforts to provide additional constraints on the ejecta properties from modeling LICIACube images are ongoing (Kolokolova et al 2022;Lolachi et al 2023;Ivanovski et al 2024).…”

Section: Ejecta Observations and Evolutionmentioning

confidence: 99%

Achievement of the Planetary Defense Investigations of the Double Asteroid Redirection Test (DART) Mission

Chabot,

Rivkin,

Cheng

et al. 2024

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NASA's Double Asteroid Redirection Test (DART) mission was the first to demonstrate asteroid deflection, and the mission's Level 1 requirements guided its planetary defense investigations. Here, we summarize DART's achievement of those requirements. On 2022 September 26, the DART spacecraft impacted Dimorphos, the secondary member of the Didymos near-Earth asteroid binary system, demonstrating an autonomously navigated kinetic impact into an asteroid with limited prior knowledge for planetary defense. Months of subsequent Earth-based observations showed that the binary orbital period was changed by –33.24 minutes, with two independent analysis methods each reporting a 1σ uncertainty of 1.4 s. Dynamical models determined that the momentum enhancement factor, β, resulting from DART's kinetic impact test is between 2.4 and 4.9, depending on the mass of Dimorphos, which remains the largest source of uncertainty. Over five dozen telescopes across the globe and in space, along with the Light Italian CubeSat for Imaging of Asteroids, have contributed to DART's investigations. These combined investigations have addressed topics related to the ejecta, dynamics, impact event, and properties of both asteroids in the binary system. A year following DART's successful impact into Dimorphos, the mission has achieved its planetary defense requirements, although work to further understand DART's kinetic impact test and the Didymos system will continue. In particular, ESA's Hera mission is planned to perform extensive measurements in 2027 during its rendezvous with the Didymos–Dimorphos system, building on DART to advance our knowledge and continue the ongoing international collaboration for planetary defense.

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3D Radiative-transfer Simulations of the Ejecta Plume Anticipated from DART Impact

Cited by 3 publications

References 37 publications

Characterization of the DART Impact Ejecta Plume on Dimorphos from LICIACube Observations

Characterization of the DART Impact Ejecta Plume on Dimorphos from LICIACube Observations

Optical Characterization of the DART Impact Plume: Importance of Realistic Ejecta Scattering Properties

Achievement of the Planetary Defense Investigations of the Double Asteroid Redirection Test (DART) Mission

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