Three-dimensional reconstruction of a comet nucleus by optimal control of Maxwell's equations: A contribution to the experiment CONSERT onboard space craft Rosetta

Electromagnetic 3D subsurface imaging with source sparsity for a synthetic object

“…It is obvious that complete data can result in more accurate reconstructions, especially, if low intensity anomalies are to be detected [31]. These two data modalities, however, seem to compare well in recovery of voids.…”

“…Travel-time data was found to be suitable for this study as it allowed a large set of three-dimensional reconstructions, and it can be considered robust with respect to uncertainty related to absorption [22], which was modeled here through a latent conductivity distribution. It is obvious that complete data can result in more accurate reconstructions, especially, if low intensity anomalies are to be detected [31]. These two data modalities, however, seem to compare well in recovery of voids.…”

“…1 W [22], to be used unless the global concentration of metals within the target is high, such as in M-type asteroids [23,24]. We focused on the lander-to-orbiter tomography scenario of CONSERT; i.e., a comet nucleus sounding experiment by radiowave transmission [1,25,26,27,28,29,30,31,32,22], extended for multiple signal sources (landers) to enable localization of intense permittivity perturbations caused by internal voids [33,2]. The number and placement of sources is an important research topic, since their relationship to the reliability of inversion is strongly indirect and depends on various factors, such as the target shape and the available structural a priori information.…”

Sparse source travel-time tomography of a laboratory target: accuracy and robustness of anomaly detection

“…The results were observed to be more accurate with respect to the recovery of the refractive index than of the volume, which can be at least partially explained by our simplified assumption of linear signal paths. Ways to improve the forward simulation include, for example, the finite-difference time-domain (FDTD) method [13,51,52]. The ranking of the source configurations suggests that a higher number of sources is preferable regardless of positioning and that a-type (category I) configurations are favorable over b-types (category II).…”

“…Currently, there is a growing interest towards non-invasive imaging of asteroids to support future planetary research and extra-terrestrial mining activities. The first attempt for tomography of a planetary object has already been implemented in the comet nucleus sounding experiment by radiowave transmission (CONSERT) [6][7][8][9][10][11][12][13][14][15] as part of the Rosetta mission. CONSERT utilizes a single transmitter or transponder positioned on a comet surface.…”