The effect of polarization in asteroid tomography
Tuumanen, Mikko (2025)
2025
Teknis-luonnontieteellinen DI-ohjelma - Master's Programme in Science and Engineering
Tekniikan ja luonnontieteiden tiedekunta - Faculty of Engineering and Natural Sciences
This publication is copyrighted. You may download, display and print it for Your own personal use. Commercial use is prohibited.
Hyväksymispäivämäärä
2025-01-28
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-202501281746
https://urn.fi/URN:NBN:fi:tuni-202501281746
Tiivistelmä
Understanding asteroid structures is vital for planetary defense, solar system exploration, and future resource utilization. Space missions like NASA’s DART and ESA’s Hera and Rosetta provide critical insights into asteroid composition and dynamics, with DART showcasing asteroid deflection techniques. These efforts enhance our ability to mitigate collision risks and explore asteroids as remnants of the early solar system. Tomographic imaging using electromagnetic waves enables detailed view of asteroid interiors, supporting both scientific discovery and practical applications in planetary defense and resource extraction.
The purpose of the study is to determine how accurately the structure of an asteroid can be calculated without considering polarization, which can save computational time. The research simulates the propagation model of electromagnetic waves to image the asteroid and compares single-component and three-component calculations. The study evaluates the accuracy of single-component versus three-component calculations in reconstructing an asteroid’s internal structure.
The study first addresses the theory relevant to the calculations, such as the derivation of the wave equation from Maxwell equations, the derivation of Leapfrog iteration formulas, and the estimation of Green’s function using Tikhonov regularized deconvolution and Born’s approximation. In addition, linearization is utilized to improve the calculations. Also the inverse methods for reconstructing the permittivity distribution such as total variation and tomographic backprojection are introduced. The numerical experiment section introduces the experiment and the asteroid model used in the experiment. Finally, the results obtained in the numerical experiment are presented.
The results of reconstructions are analyzed by overlaps between estimated parts and real parts with inversion methods such as back projection and total variation. These parts are voids alone and boundary and voids together. Overlaps are studied for reconstructions with noiseless signal and noisy signal. Noisy signal reconstructions have been tested with added Gaussian noise and illustrated with box plots showing the quantiles of overlaps. Also the effect of envelope has studied in similar way.
The purpose of the study is to determine how accurately the structure of an asteroid can be calculated without considering polarization, which can save computational time. The research simulates the propagation model of electromagnetic waves to image the asteroid and compares single-component and three-component calculations. The study evaluates the accuracy of single-component versus three-component calculations in reconstructing an asteroid’s internal structure.
The study first addresses the theory relevant to the calculations, such as the derivation of the wave equation from Maxwell equations, the derivation of Leapfrog iteration formulas, and the estimation of Green’s function using Tikhonov regularized deconvolution and Born’s approximation. In addition, linearization is utilized to improve the calculations. Also the inverse methods for reconstructing the permittivity distribution such as total variation and tomographic backprojection are introduced. The numerical experiment section introduces the experiment and the asteroid model used in the experiment. Finally, the results obtained in the numerical experiment are presented.
The results of reconstructions are analyzed by overlaps between estimated parts and real parts with inversion methods such as back projection and total variation. These parts are voids alone and boundary and voids together. Overlaps are studied for reconstructions with noiseless signal and noisy signal. Noisy signal reconstructions have been tested with added Gaussian noise and illustrated with box plots showing the quantiles of overlaps. Also the effect of envelope has studied in similar way.