Biondi's "Harmonia SAR" examined and found wanting

While we were all waiting for a more digestible form of the Malaga/Biondi presentation on the Khafre Project, I came across a very interesting text here: "I tried to reproduce the viral satellite radar paper about the pyramids [https://arxiv.org/abs/2208.00811]. Here's what I found" (Simone @theotherpomp Apr 21). I do not know who the author is, but their method and conclsions seem worthy of discussion.

The critique begins by outlining Filippo Biondi's extraordinary claim that satellite radar analysis has revealed vast underground structures beneath the Giza pyramids, including shafts extending hundreds of metres underground and structures more than a kilometre deep. These claims were presented as credible because the method was also said to have successfully detected the known chambers within the Great Pyramid and the underground Gran Sasso laboratory in Italy.

The author first examines whether the published single-pass SAR method is physically capable of detecting the known chambers inside the Great Pyramid. By reconstructing the imaging geometry using real satellite parameters, they conclude that the method's vertical resolution is approximately 285 metres, far too coarse to distinguish structures such as the King's Chamber and Queen's Chamber, which lie only a few tens of metres apart. This suggests that the claimed detections are not physically plausible using the published technique.

To test this conclusion empirically, the author compares the radar response of the Great Pyramid with nearby empty desert using the same processing approach described in the paper. Across 240 experiments varying multiple parameters, the method fails to distinguish the pyramid from the surrounding landscape; indeed, the empty desert often produces stronger responses than the pyramid itself. Expanding the analysis to twenty different locations (including other monuments, urban areas, farmland, and the Nile River), produces remarkably similar results in every case.

The author then investigates why the method appears to generate underground structures everywhere. Through simulation, they show that sparse tomographic reconstructions can create convincing but entirely artificial deep structures, even when only shallow features are present in the original model. As the amount of genuine observational data increases, these apparent deep structures disappear, suggesting that they are reconstruction artefacts rather than real objects.

This explanation is then applied to the Gran Sasso laboratory, which the author argues may represent a case of identifying an expected feature within a reconstruction method that naturally generates structured responses at many depths. The critique also identifies a possible inconsistency in the original study: although the published method is described as a single-pass technique, the paper references multiple acquisitions and processing tools typically associated with multi-pass interferometric SAR analysis.

The author ultimately concludes that the published single-pass method cannot support the extraordinary claims being made for it. They suggest that any genuine detections of known structures may have resulted from a different, multi-pass workflow than the one described in the paper, while the dramatic deep structures beneath Giza are more plausibly explained as artefacts generated by an under-constrained reconstruction process.