Dynamical effects of thermal emission on asteroids

Mysen, E.

doi:10.1111/j.1745-3933.2007.00405.x

Cited by 6 publications

(15 citation statements)

References 22 publications

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“…As discussed in Mysen (2007) and Mysen (2008), the insolation functionˆ can be approximated by the expression…”

Section: Heat Transport Of An Asteroidmentioning

confidence: 99%

“…With ϑ 0 = 0.106, ϑ 1 = 0.500, and ϑ 2 = 0.4244, the average deviation betweenˆ and is only 0.034 (Mysen 2007;Mysen 2008), which should be compared to the maximumˆ = 1. Note that the effect of the step function Θ has already been included at this level, and that when we later need to integrate over the surface of the asteroid to find the total recoil force or torques, the integration can be done over the whole surface, and not only the day side.…”

Section: Heat Transport Of An Asteroidmentioning

confidence: 99%

“…If we, for the moment, define the orbit plane of the asteroid as our reference plane, the direction cosines of the Sun can be written (Mysen 2008) γ ,…”

Section: Heat Transport Of An Asteroidmentioning

confidence: 99%

“…In Mysen (2008), we circumvented the problem with a simple approximation of the insolation pattern, encompassing the need for a detailed characterization of the transition from day to night on the asteroid. Overall results from previous studies were recovered.…”

Section: Introductionmentioning

confidence: 99%

“…However, as in all the referenced analytic studies, we implemented the thermal lag by delaying the response of the force with respect to noon at the asteroid, possibly yielding unphysical results. We connect the Mysen (2008) approach directly to the physics of the problem, which allows for a proper evaluation of the different components' relative importance.…”

Section: Introductionmentioning

confidence: 99%

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An analytical model for YORP and Yarkovsky effects with a physical thermal lag

Mysen¹

2008

A&A

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Asteroids absorb solar radiation, which is later re-emitted. In this paper, an analytic approach for the description of the effects of this thermal emission on the rotation and orbit of an asteroid of unspecified shape is presented. The theory is connected directly to the physics of the problem, and the important results caused by a delayed thermal response of the surface are, therefore, parameterized by the fundamental surface properties of the asteroid. Overall results of previous numerical studies are recovered and an application to the elongated and irregularly-shaped asteroid Eros shows correspondence. The dependency of the derived differential equations on the dynamical variables is explicit and simple. We argue that if the transport of asteroids within the main belt is caused by thermal emission, then there is a preference for the shapes of Earth orbit crossing, regolith-covered asteroids.

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“…As discussed in Mysen (2007) and Mysen (2008), the insolation functionˆ can be approximated by the expression…”

Section: Heat Transport Of An Asteroidmentioning

confidence: 99%

Section: Heat Transport Of An Asteroidmentioning

confidence: 99%

“…If we, for the moment, define the orbit plane of the asteroid as our reference plane, the direction cosines of the Sun can be written (Mysen 2008) γ ,…”

Section: Heat Transport Of An Asteroidmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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An analytical model for YORP and Yarkovsky effects with a physical thermal lag

Mysen¹

2008

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Extreme sensitivity of the YORP effect to small-scale topography

Statler

2009

Icarus

133

165

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Radiation recoil (YORP) torques are shown to be extremely sensitive to small-scale surface topography, using numerical simulations. Starting from a set of "base objects" representative of the near-Earth object population, random realizations of three types of small-scale topography are added: Gaussian surface fluctuations, craters, and boulders. For each, the expected relative errors in the spin and obliquity components of the YORP torque caused by the observationally unresolved small-scale topography are computed. Gaussian power, at angular scales below an observational limit, produces expected errors of order 100% if observations constrain the surface to a spherical harmonic order l 10. For errors under 10%, the surface must be constrained to at least l = 20. A single crater with diameter roughly half the object's mean radius, placed at random locations, results in expected errors of several tens of percent. The errors scale with crater diameter D as D 2 for D > 0.3 and as D 3 for D < 0.3 mean radii. Objects that are identical except for the location of a single large crater can differ by factors of several in YORP torque, while being photometrically indistinguishable at the level of hundredths of a magnitude. Boulders placed randomly on identical base objects create torque errors roughly 3 times larger than do craters of the same diameter, with errors scaling as the square of the boulder diameter. A single boulder comparable to Yoshinodai on 25143 Itokawa, moved by as little as twice its own diameter, can alter the magnitude of the torque by factors of several, and change the sign of its spin component at all obliquities. Most of the total torque error produced by multiple unresolved craters is contributed by the handful of largest craters; but both large and small boulders contribute comparably to the total boulder-induced error. A YORP torque prediction derived from groundbased data can be expected to be in error by of order 100% due to unresolved topography. Small surface changes caused by slow spin-up or spin-down may have significant stochastic effects on the spin evolution of small bodies. For rotation periods between roughly 2 and 10 hours, these unpredictable changes may reverse the sign of the YORP torque. Objects in this spin regime may random-walk up and down in spin rate before the rubble-pile limit is exceeded and fissioning or loss of surface objects occurs. Similar behavior may be expected at rotation rates approaching the limiting values for tensile-strength dominated objects.

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YORP Effect on Asteroid 162173 Ryugu: Implications for the Dynamical History

et al. 2021

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The Hayabusa2 spacecraft arrived at the target asteroid in June 2018 and started its homeward journey to Earth in November 2019 after an approximately 17-month asteroid-proximity phase. The capsule container with the sample from Ryugu was delivered to Earth in December 2020. The mission included two successful touchdowns to sample the surface material, an artificial cratering experiment, and deployments of a lander and rovers. Hayabusa2 revealed the nature of the rocky surface and its spinning-top shape (Watanabe et al., 2019). The spinning-top-shaped body has an elevated ridge in the equatorial region and a flat cross-section in the midlatitude region, unlike spherical or ellipsoidal objects. The spinning-top shape may be the consequence of deformation induced by fast rotation in the past (Walsh et al., 2008). According to a finite-element-method analysis by Hirabayashi et al. (2019), fast rotation with a period of approximately 3.

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Dynamical effects of thermal emission on asteroids

Cited by 6 publications

References 22 publications

An analytical model for YORP and Yarkovsky effects with a physical thermal lag

An analytical model for YORP and Yarkovsky effects with a physical thermal lag

Extreme sensitivity of the YORP effect to small-scale topography

YORP Effect on Asteroid 162173 Ryugu: Implications for the Dynamical History

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