Abstract
Satellite information in support to archaeological research in Egypt.
Dr. Maurizio Fea, Dr. Chris Stewart, Dr. Stefano Gusmano
Team “Satellite remote Sensing in support to Egyptological Research, National Research Council of Italy (CNR – ISMA)
Preliminary results of satellite remote sensing analyses to support The Seven Plagues project are presented. The work conducted to date includes the procurement of both optical and Synthetic Aperture Radar (SAR) data from various sensors. Data processing has been performed to enhance subtle topographic or moisture variations, to detect features buried beneath the sand, and to better understand the geological and geographical context of the region surveyed. An interpretation of the imagery is being carried out by archaeologists, geologists and other experts, with a view to supporting the objectives of the project.
A very large dataset of 60 satellite images acquired by the Phased Array type L-band Synthetic Aperture Radar (PALSAR) sensor on-board the Japanese Advanced Land Observing Satellite (ALOS) has been obtained for the analyses. The data covers a broad region from the eastern border of Egypt in North Sinai to Saqqara. PALSAR has characteristics that render it very interesting for archaeological research. The sensor is an active instrument sending long wavelength (23 centimetre) radiation to the Earth and measuring the return signal. Radiation at this wavelength is more likely to pass through dry sand with a very low dielectric constant, and hence detect potential archaeological features buried beneath. Moreover, the Synthetic Aperture Radar (SAR) data is sensitive to surface roughness and moisture, subtle variations of which can be due to underlying structures. A technique called radar interferometry uses SAR data to map terrain to a high precision, this has also been applied in the project.
Similar analyses has been undertaken with another SAR sensor, Cosmo SkyMed, which is flown on a constellation of Italian satellites. Cosmo SkyMed SAR operates at much shorter wavelengths than PALSAR (3.1cm) and much higher spatial resolution (2.5m, data may also been obtained at 1m). While the shorter wavelength has theoretically less capability of dry sand penetration, the increased spatial resolution greatly benefits the research on the micro scale.
Optical imagery from satellite sensors at various spatial resolutions and in different spectral bands have also been obtained for the analyses. These have provided additional information on the study area, at different scales, and have served as a comparison with the SAR data to better understand features of interest.
It is hoped that the preliminary results presented here will demonstrate the utility of satellite remote sensing for archaeological research and will stimulate further use of satellite resources.
