# Bistatic full-wave radar tomography detects deep interior voids, cracks and boulders in a rubble-pile asteroid model

## TL;DR

This study demonstrates that sparse bistatic full-wave radar tomography can effectively detect internal features like voids, cracks, and boulders in a complex rubble-pile asteroid model, enhancing asteroid interior imaging capabilities.

## Contribution

It shows that bistatic CRT can identify internal asteroid features with sparse measurements and noise robustness, advancing asteroid interior exploration methods.

## Key findings

- Detects surface layers, voids, and boulders with -10 dB noise level
- Bistatic setup improves inversion robustness over monostatic
- Reconstructing smooth backgrounds remains challenging, suggesting need for complementary techniques

## Abstract

In this paper, we investigate full-wave computed radar tomography (CRT) using a rubble-pile asteroid model in which a realistic shape (Itokawa) is coupled with a synthetic material composition and structure model. The aim is to show that sparse bistatic radar measurements can distinguish details inside a complex-structured rubble-pile asteroid. The results obtained suggest that distinct local permittivity distribution changes such as surface layers, voids, low-permittivity anomalies, high-permittivity boulders, and cracks can be detected with bistatic CRT, when the total noise level in the data is around -10 dB with respect to the signal amplitude. Moreover, the bistatic measurement set-up improves the robustness of the inversion compared to the monostatic case. Reconstructing the smooth Gaussian background distribution was found to be difficult with the present approach, suggesting that complementary techniques, such as gravimetry, might be needed to improve the reliability of the inference in practice.