Planetary Geology with Imaging Radar: Insights from Earth-based Lunar Studies, 2001–2015

Campbell, B. A.

doi:10.1088/1538-3873/128/964/062001

Cited by 13 publications

(10 citation statements)

References 83 publications

(125 reference statements)

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“…The power and polarization state of a radar signal reflected from a planetary body varies with surface roughness, texture, composition, and incidence angle. Polarimetric decomposition and radar scattering theory are often employed to determine the dependence of signal power and polarization on surface roughness and incidence angle (e.g., Campbell, 2016; Carter et al., 2011; Raney et al., 2012; Virkki & Muinonen, 2016). The surface texture and composition predominantly affect the power of the reflected signal, as well as the penetration depth of the incident signal.…”

Section: Introductionmentioning

confidence: 99%

Modeling the Dielectric Properties of Minerals From Crystals to Bulk Powders for Improved Interpretation of Asteroid Radar Observations

et al. 2020

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Planetary radar has provided a growing number of data sets on the inner planets and near‐Earth and main belt asteroid populations in the solar system. Physical interpretation of radar data for inference of surface properties requires constraints on the constitutive parameters of the material making up a given surface. In this study, the complex permittivity of seven minerals as a function of frequency and porosity is measured using the coaxial transmission line method to determine the mixing equation that best describes the relationship between the real part of the complex permittivity of single mineral crystals and granular mineral powders. We find the Looyenga‐Landau‐Lifshitz and Bruggeman symmetric mixing equations to describe our experimental results with the highest accuracy. The variation in the real part of the permittivity of solid mineral crystals between different minerals is shown to depend on the grain density and the chemical composition of the minerals. These mixing relationships are incorporated into an asteroid radar model and used to calculate the porosity in the near‐surface of seven asteroids visited by robotic spacecraft using Earth‐based radar observations. The results of the asteroid radar model support the presence of significant porosity in the boulders on the surface of asteroid 101955 Bennu. This research highlights the ability of radar to measure the porosity on asteroid surfaces and provides theoretical and experimental justification for the inversion of permittivity to bulk density assumed by the asteroid radar model.

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Section: Introductionmentioning

confidence: 99%

Modeling the Dielectric Properties of Minerals From Crystals to Bulk Powders for Improved Interpretation of Asteroid Radar Observations

et al. 2020

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“…However, the radar is also highly capable of observing meteors entering the Earth's atmosphere (Pellinen-Wannberg et al, 2016), tracking orbital debris (Vierinen et al, 2019a), and even mapping the Moon (e.g. Thompson et al, 2016;Campbell, 2016;Vierinen et al, 2017b;Vierinen and Lehtinen, 2009).…”

Section: Introductionmentioning

confidence: 99%

Radar observability of near-Earth objects using EISCAT 3D

et al. 2020

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Abstract. Radar observations can be used to obtain accurate orbital elements for near-Earth objects (NEOs) as a result of the very accurate range and range rate measureables. These observations allow the prediction of NEO orbits further into the future and also provide more information about the properties of the NEO population. This study evaluates the observability of NEOs with the EISCAT 3D 233 MHz 5 MW high-power, large-aperture radar, which is currently under construction. Three different populations are considered, namely NEOs passing by the Earth with a size distribution extrapolated from fireball statistics, catalogued NEOs detected with ground-based optical telescopes and temporarily captured NEOs, i.e. mini-moons. Two types of observation schemes are evaluated, namely the serendipitous discovery of unknown NEOs passing the radar beam and the post-discovery tracking of NEOs using a priori orbital elements. The results indicate that 60–1200 objects per year, with diameters D>0.01 m, can be discovered. Assuming the current NEO discovery rate, approximately 20 objects per year can be tracked post-discovery near the closest approach to Earth. Only a marginally smaller number of tracking opportunities are also possible for the existing EISCAT ultra-high frequency (UHF) system. The mini-moon study, which used a theoretical population model, orbital propagation, and a model for radar scanning, indicates that approximately seven objects per year can be discovered using 8 %–16 % of the total radar time. If all mini-moons had known orbits, approximately 80–160 objects per year could be tracked using a priori orbital elements. The results of this study indicate that it is feasible to perform routine NEO post-discovery tracking observations using both the existing EISCAT UHF radar and the upcoming EISCAT 3D radar. Most detectable objects are within 1 lunar distance (LD) of the radar. Such observations would complement the capabilities of the more powerful planetary radars that typically observe objects further away from Earth. It is also plausible that EISCAT 3D could be used as a novel type of an instrument for NEO discovery, assuming that a sufficiently large amount of radar time can be used. This could be achieved, for example by time-sharing with ionospheric and space-debris-observing modes.

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“…Ground based radio remote sensing of planetary surfaces is a remote sensing technique wherein a planetary target is illuminated by a radar transmitter on the surface of Earth. This is a tool that can provide insights into the formative processes of the surfaces of the inner planets, as well as the conditions in the early history of the Solar System (Ostro, 1993;Campbell, 2016). Radar mapping of planetary surfaces provides information about the properties of the upper layers of the planet's surface, and can also provide accurate information about an object's rotation (Campbell et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Planetary Radar Science Case for EISCAT 3D

Tveito¹,

Vierinen²,

Gustavsson³

et al. 2020

Preprint

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Abstract. Ground-based inverse synthetic aperture radar is a tool that can provide insights into the early history and formative processes of planetary bodies in the inner Solar System. This information is gathered by measuring the scattering matrix of the target body, providing composite information about the physical structure and chemical makeup of its surface and subsurface down to the penetration depth of the radio wave. This work describes the technical capabilities of the upcoming 233 MHz EISCAT 3D radar facility for measuring planetary surfaces. Estimates of the achievable signal-to-noise ratios for terrestrial target bodies are provided. While Venus and Mars can possibly be detected, only the Moon is found to have sufficient signal-to-noise ratio to allow high resolution mapping to be performed. The performance of the EISCAT 3D antenna layout is evaluated for interferometric range-Doppler disambiguation and it is found to be well suited for this task, providing up to 20 dB of separation between Doppler north and south hemispheres in our case study. The low frequency used by EISCAT 3D is more affected by the ionosphere than higher frequency radars. The magnitude of the Doppler broadening due to ionospheric propagation effects associated with traveling ionospheric disturbances has been estimated.The effect is found to be significant, but not severe enough to prevent high resolution imaging. A survey of Lunar observing opportunities between 2022 and 2040 are evaluated by investigating the path of the sub-radar point when the Moon is above the local radar horizon. During this time, a good variety of look directions and Doppler equator directions are found, with observations opportunities available for approximately ten days every lunar month. EISCAT 3D will be able to provide new high quality polarimetric scattering map of the near-side of the Moon with a previously unused wavelength of 1.3 m, which provides a good compromise between radio wave penetration depth and Doppler resolution.

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Planetary Geology with Imaging Radar: Insights from Earth-based Lunar Studies, 2001–2015

Cited by 13 publications

References 83 publications

Modeling the Dielectric Properties of Minerals From Crystals to Bulk Powders for Improved Interpretation of Asteroid Radar Observations

Modeling the Dielectric Properties of Minerals From Crystals to Bulk Powders for Improved Interpretation of Asteroid Radar Observations

Radar observability of near-Earth objects using EISCAT 3D

Planetary Radar Science Case for EISCAT 3D

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