School

School of Humanities and Sciences

Department

Physics and Astronomy

ICC Theme

Inquiry, Imagination, and Innovation

Date

2-4-2019 1:40 PM

Abstract

The Yarkovsky effect is a non-gravitational phenomenon resulting from anisotropic thermal emissions of rotating asteroids. This complex effect has multiple variants and is delicately governed by an array of asteroid properties ranging from composition to orbital inclination. It took more than 100 years between theory and detection (first seen in asteroid 6489 Golevka in 2003). Now, the near-earth asteroid 101955 Bennu has shown a mean semimajor axis drift da/dt = 284 ± 1.5 m/year due to the Yarkovsky effect. Non-gravitational drift can greatly affect the probability of asteroid impact with earth making accurate modeling of the Yarkovsky effect a high priority for NASA. The OSIRIS-REx mission is currently delivering a satellite into orbit around Bennu. Amongst the mission objectives is the measurement of the asteroid’s thermophysical properties that contribute to the Yarkovsky effect, such as the thermal conductivity of the surface. This is important because the observations necessary to measure thermophysical properties from Earth are much more difficult than from a spacecraft platform. Additionally, estimates of immeasurable properties, such as bulk density of asteroids, become possible with a comprehensive understanding of the force and accurate measurements of its magnitude. Because the Yarkovsky effect is so heavily outweighed by gravitational forces, and the highly elliptical orbits of most near-earth asteroids make accurate orbital tracking next to impossible, incredible precision must be practiced when searching for this effect from the ground. Bennu, with the “eyes” of the OSIRIS-REx mission, acts as the perfect aid for observing and understanding the characteristics of this important non-gravitational effect that makes asteroid orbits so hard to predict into the future.

Document Type

Poster

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Apr 2nd, 1:40 PM

The Yarkovsky Effect on Near-Earth Asteroid (101955) Bennu, Target of the Osiris ­Rex Mission: A Review of the Literature

The Yarkovsky effect is a non-gravitational phenomenon resulting from anisotropic thermal emissions of rotating asteroids. This complex effect has multiple variants and is delicately governed by an array of asteroid properties ranging from composition to orbital inclination. It took more than 100 years between theory and detection (first seen in asteroid 6489 Golevka in 2003). Now, the near-earth asteroid 101955 Bennu has shown a mean semimajor axis drift da/dt = 284 ± 1.5 m/year due to the Yarkovsky effect. Non-gravitational drift can greatly affect the probability of asteroid impact with earth making accurate modeling of the Yarkovsky effect a high priority for NASA. The OSIRIS-REx mission is currently delivering a satellite into orbit around Bennu. Amongst the mission objectives is the measurement of the asteroid’s thermophysical properties that contribute to the Yarkovsky effect, such as the thermal conductivity of the surface. This is important because the observations necessary to measure thermophysical properties from Earth are much more difficult than from a spacecraft platform. Additionally, estimates of immeasurable properties, such as bulk density of asteroids, become possible with a comprehensive understanding of the force and accurate measurements of its magnitude. Because the Yarkovsky effect is so heavily outweighed by gravitational forces, and the highly elliptical orbits of most near-earth asteroids make accurate orbital tracking next to impossible, incredible precision must be practiced when searching for this effect from the ground. Bennu, with the “eyes” of the OSIRIS-REx mission, acts as the perfect aid for observing and understanding the characteristics of this important non-gravitational effect that makes asteroid orbits so hard to predict into the future.

 

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