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Planetary Society STEP Grant 2021:

Demystifying Near-Earth Asteroids

(D-NEAs)



What is the D-NEAs project

  • Near-Earth asteroids (NEAs) are technically defined as a sub-population of asteroids that come closer to the Sun than 1.3 average distances between the Earth and the Sun. More practical terms imply that NEAs move in proximity to Earth, representing both an opportunity and a threat to our civilization. NEAs owe their origins to main-belt asteroids and are, by definition, parent bodies of meteorite samples. Therefore, understanding NEAs connections is one of the central questions for modern studies of small solar system objects. Optimizing the synergies between science, human exploration, and resource utilization, is the ultimate grand challenge and opportunity for NEAs in the twenty-first century. A critical prerequisite is to learn a great deal more about their nature. In this respect, space-borne observations and missions are priceless but possible for a limited number of objects. Yet, asteroid surfaces and internal structures are diverse, and an alternative approach is needed to estimate the properties of many objects. The D-NEAs project aims to develop a novel method enabling the characterization of asteroids from ground-based data. The proposed project is of a very high benefit-to-cost ratio and directly contributes to two Core Enterprises of the Planetary Society.
  • Knowledge of the physical and surface properties of most NEAs lags far behind the current rate of their discoveries. Still, asteroid surfaces and internal structures are very diverse, and knowledge derived from a limited number of asteroids typically could not be safely extrapolated to a large number of objects. The situation calls for an alternative approach that permits estimating asteroids' properties for a much larger number of NEAs.
  • The Demystifying Near-Earth Asteroids (D-NEAs) is the Planetary Society STEP Grant 2021 project aiming to develop a novel method that directly characterises asteroids primarily from ground-based data. In particular, the project's objective is to develop a model to characterise surface thermal properties.
  • The idea is based on the Yarkovsky effect, a non-gravitational phenomenon that causes objects to undergo orbital semi-major axis drift. The effect joins the asteroid’s orbital dynamics, composition, and physical properties. Our idea to derive the surface thermal properties of near-Earth objects is built around these facts. Theoretical models of the Yarkovsky effect allow predicting the semi-major axis drift, assuming a set of input parameters is available. On the other hand, astrometric observations and orbit determination procedures allow detecting the asteroid’s semi-major axis drift in motion. Therefore, at least one asteroid’s property that determines the drift rate could be estimated by comparing the model’s predicted da/dt and measured (da/dt)m magnitude of the effect, as illustrated in Fig. 1:

    Especially critical are the thermal conductivity uncertainties that span a range of about four orders of magnitude. It is also a key for thermal inertia estimation, which is diagnostic of surface porosity and cohesion.
  • Duration: 01.04.2022 -- 31.03.2024

    • Objectives

    • Modeling surface thermal properties from the ground based data
    • Development of the basic Monte Carlo model
    • Investigating role of the orbital eccentricity
    • Heterogeneity of the object density
    • Accounting for variable thermal inertia along the orbit
    • Parallelization of the Monte-Carlo-based code
    • Supporting telescopic observations

    Acknowledgment

  • We appreciate support from a Planetary Society STEP Grant, made possible by the generosity of The Planetary Society' members.

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