Spin state evolution of (99942) Apophis during its 2029 Earth encounter

Benson, Conor J.; Scheeres, Daniel J.; Brozović, M.; Chesley, Steven R.; Pravec, Petr; Scheirich, P.

doi:10.1016/j.icarus.2022.115324

Cited by 14 publications

(12 citation statements)

References 18 publications

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“…This means that the best time to detect active tidal resurfacing is during the last hour before Apophis reaches perigee, after which the surface grains reach new equilibrium positions because the rates of change in the patch slopes become smaller. We also note that the global tidal resurfacing that we predict is not extensive, which is consistent with conclusions from previous studies (Yu et al 2014;Benson et al 2022). However, our results still indicate that tidal resurfacing may be seen in certain localized regions-initially high-sloped areas and mid-sloped regions with significant positive slope variation.…”

Section: Discussionsupporting

confidence: 93%

“…3.1, we find that the encounter orientation may be a dominant factor in predicting locations and total areas of resurfacing during the 2029 Apophis-Earth close encounter because different encounter orientations cause different surface slope profiles. To explore the influence of encounter orientation on regions of tidal resurfacing, we randomly select the encounter orientations rather than propagating from the current spin state because predicting the spin orientation of Apophis at the time of its closest approach to the Earth using the currently existing data still has a large uncertainty (Pravec et al 2014;Benson et al 2022). We originally conduct 30 simulations with different encounter orientations but first introduce 3 representative cases chosen to maximize observable differences in resurfacing as a result of encounter orientation.…”

Section: Influence Of Encounter Orientation On Expected Resurfaced Areamentioning

confidence: 99%

“…Apophis will have a definite change in its orbit and rotational properties in response to Earth's tidal torques (Scheeres et al 2005;Farnocchia et al 2013;Souchay et al 2014Souchay et al , 2018DeMartini et al 2019;Benson et al 2022). These orbital and rotational changes will likely occur with magnitudes sufficient to be detectable by ground-based telescopes.…”

Section: Introductionmentioning

confidence: 99%

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Tidal resurfacing model for (99942) Apophis during the 2029 close approach with Earth

DeMartini¹,

Kim²

2023

Preprint

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We numerically investigate tidally induced surface refreshing on Apophis during its close approach with Earth within a perigee distance of 5.96 Earth radii on April 13, 2029. We implement a tidal resurfacing model with two stages: dynamics modeling of the entire body to determine time-varying accelerations and surface slope profiles felt by each surface patch during the 6-h-long closest encounter, and DEM modeling to track motions of surface grains in localized patches. The surface slope profiles and measured grain motions are combined to statistically extrapolate the 'expected' percentage of resurfaced area. Using the tidal resurfacing model, we present surface maps showing the total expected resurfacing on Apophis given 3 representative encounter orientations. Our simulation results indicate that tidal resurfacing, limited to certain localized regions, will likely occur half an hour before perigee and on the scale of 1 per cent of Apophis's entire surface area. Our models indicate that the most likely locations to detect tidal resurfacing are: initially high-sloped regions (> 30 • ) regardless of the encounter orientation of Apophis, and mid-sloped regions (15 • -30 • ) that experience a significant positive slope variation (> 0.5 • ), which is mainly controlled by the encounter orientation. Expected data from ground-based observations of the 2029 flyby will help us better constrain the targeted locations likely to experience tidal resurfacing. We thus expect to find evidence supporting tidal resurfacing via further analysis of post-encounter surface images or albedo changes at the expected resurfaced areas.

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Section: Discussionsupporting

confidence: 93%

Section: Influence Of Encounter Orientation On Expected Resurfaced Areamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Tidal resurfacing model for (99942) Apophis during the 2029 close approach with Earth

DeMartini¹,

Kim²

2023

Preprint

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“…However, Apophis' rotation state is currently in the process of NPA rotation and is slowly tumbling (Pravec et al 2014;Benson et al 2023). Due to the difficulties of interpreting data from this sort of light curve, we must develop a sophisticated NPA rotation model for incorporation into SAMUS.…”

Section: Applicability Of Samus To 99942 Apophismentioning

confidence: 99%

“…The potential effects of Apophis' near-Earth flyby on the geophysical, photometric, and rotational states have been investigated. Benson et al (2023) demonstrated that the close encounter will induce sufficient tidal torques to modify the rotational state. The tidal forces will also be sufficient to produce resurfacing events that could modify the photometric properties (Yu et al 2014;Kim et al 2023).…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulations of Tidal Deformation and Resulting Light Curves of Small Bodies: Material Constraints of 99942 Apophis and 1I/‘Oumuamua

et al. 2023

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In this paper, we present an open-source software (Simulator of Asteroid Malformation Under Stress, SAMUS) that simulates constant-density, constant-viscosity liquid bodies subject to tidal forces for a range of assumed viscosities and sizes. This software solves the Navier–Stokes equations on a finite-element mesh, incorporating the centrifugal, Coriolis, self-gravitational, and tidal forces. The primary functionality is to simulate the deformation of minor bodies under the influence of tidal forces. It may therefore be used to constrain the composition and physical structure of bodies experiencing significant tidal forces, such as 99942 Apophis and 1I/‘Oumuamua. We demonstrate that SAMUS will be useful to constrain the material properties of Apophis during its near-Earth flyby in 2029. Depending on the material properties, Apophis may experience an area change of up to 0.5%, with similar effects on the photometric brightness. We also apply SAMUS to constrain the material dynamic viscosity of 1I/‘Oumuamua, the first interstellar object discovered traversing the inner solar system. ‘Oumuamua experienced a close approach to the Sun at perihelion (q ≃ 0.25 au) during which there were significant tidal forces that may have caused deformation of the body. This deformation could have lead to observable changes in the photometric light curve based on the material properties. The application of SAMUS to produce synthetic observations which incorporate tidal deformation effects demonstrates that no deformation—an infinite dynamic viscosity—best reproduces the photometric data. While these results indicate that ‘Oumuamua did not experience significant tidal deformation, a sophisticated model incorporating nonprincipal axis rotation is necessary to conclusively analyze both ‘Oumuamua and Apophis.

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Tidal resurfacing model for (99942) Apophis during the 2029 close approach with Earth

Kim

DeMartini

Richardson

et al. 2023

Monthly Notices of the Royal Astronomical Society

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We numerically investigate tidally induced surface refreshing on Apophis during its close approach with Earth within a perigee distance of 5.96 Earth radii on April 13, 2029. We implement a tidal resurfacing model with two stages: dynamics modeling of the entire body to determine time-varying accelerations and surface slope profiles felt by each surface patch during the 6-h-long closest encounter, and DEM modeling to track motions of surface grains in localized patches. The surface slope profiles and measured grain motions are combined to statistically extrapolate the ‘expected’ percentage of resurfaced area. Using the tidal resurfacing model, we present surface maps showing the total expected resurfacing on Apophis given 3 representative encounter orientations. Our simulation results indicate that tidal resurfacing, limited to certain localized regions, will likely occur half an hour before perigee and on the scale of 1 per cent of Apophis’s entire surface area. Our models indicate that the most likely locations to detect tidal resurfacing are: initially high-sloped regions (>30○) regardless of the encounter orientation of Apophis, and mid-sloped regions (15○–30○) that experience a significant positive slope variation (>0.5○), which is mainly controlled by the encounter orientation. Expected data from ground-based observations of the 2029 flyby will help us better constrain the targeted locations likely to experience tidal resurfacing. We thus expect to find evidence supporting tidal resurfacing via further analysis of post-encounter surface images or albedo changes at the expected resurfaced areas.

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Spin state evolution of (99942) Apophis during its 2029 Earth encounter

Cited by 14 publications

References 18 publications

Tidal resurfacing model for (99942) Apophis during the 2029 close approach with Earth

Tidal resurfacing model for (99942) Apophis during the 2029 close approach with Earth

Numerical Simulations of Tidal Deformation and Resulting Light Curves of Small Bodies: Material Constraints of 99942 Apophis and 1I/‘Oumuamua

Tidal resurfacing model for (99942) Apophis during the 2029 close approach with Earth

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