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The Relevance of Thermal Inertia to Planetary Defense

Harris, Alan and Drube, Line (2017) The Relevance of Thermal Inertia to Planetary Defense. Planetary Defence Conference 2017, 15-19 May 2017, Tokyo, Japan.

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Abstract

One of the largest uncertainties in the outcome of an attempt to deflect an asteroid with a kinetic impactor is the momentum enhancement factor, β, which is related to the amount of momentum carried off by ejecta produced by the impact. The momentum enhancement of an asteroid due to ejecta is proportional to (β-1). The amount and velocity distribution of ejecta depends on the porosity and density of the surface material, characteristics that are closely related to thermal inertia. We show how it is possible to estimate the surface thermal inertia of an asteroid from Earth-based infrared observations, such as those carried out by NASA’s Wide-field Infrared Survey Explorer (WISE) space telescope, and thereby provide information on physical characteristics relevant to asteroid deflection. Recent research results suggest the thermal inertia of near-Earth objects (NEOs), and therefore the density and thermal conductivity of near-surface material, increases rapidly with depth within the topmost 1m. If density increases with depth, the value of β relevant to the kinetic impactor concept will be larger in general than that implied by the properties of material on the surface. Furthermore, thermal conductivity is an important parameter in calculations of the Yarkovsky orbital drift of NEOs. We briefly describe the relevant observational results and discuss their implications for the effectiveness of the kinetic impactor deflection concept, and for calculations of the Yarkovsky effect relevant to the impact hazard.

Item URL in elib:https://elib.dlr.de/111693/
Document Type:Conference or Workshop Item (Speech)
Title:The Relevance of Thermal Inertia to Planetary Defense
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Harris, AlanAlan.Harris (at) dlr.dehttps://orcid.org/0000-0001-8548-8268
Drube, LineLine.Drube (at) dlr.dehttps://orcid.org/0000-0003-2486-8894
Date:2017
Refereed publication:No
Open Access:Yes
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Status:Published
Keywords:Asteroid surface structure, thermal inertia, kinetic impactor, Yarkovsky effect
Event Title:Planetary Defence Conference 2017
Event Location:Tokyo, Japan
Event Type:international Conference
Event Dates:15-19 May 2017
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Science and Exploration
DLR - Research area:Raumfahrt
DLR - Program:R EW - Erforschung des Weltraums
DLR - Research theme (Project):R - Vorhaben Planetary Evolution and Life
Location: Berlin-Adlershof
Institutes and Institutions:Institute of Planetary Research > Leitungsbereich PF
Deposited By: Drube, Line
Deposited On:20 Jul 2017 14:26
Last Modified:31 Jul 2019 20:08

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