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Saturday, October 31, 2015

Techniques for Scanning the Pyramids

Techniques for Scanning the Pyramids

Could the ScanPyramids Project unlock the secrets of Egypt’s Wonders of the Ancient World, asks Nevine El-Aref

Four millennia after their construction, the ancient Egyptian Pyramids at Giza still conceal their secrets. Although research has been carried out on them throughout history, many questions remained unanswered. How were the pyramids built? Why do they have different shapes? How could they have lasted for 4,500 years without collapsing? Why do the inner structures of the pyramids have such inexplicable anomalies? These are just a few of the unanswered questions that are still puzzling today’s archaeologists.

However, with the help of modern non-invasive technology many of these questions may now be finally resolved. Under the motto “Just because a mystery is 4,500 years old doesn’t mean it can’t be solved,” the Ministry of Antiquities has initiated the ScanPyramids Project in collaboration with the Faculty of Engineering at Cairo University and the French Heritage Innovation and Preservation (HIP) Institute.

The project aims at probing the heart of Egypt’s pyramids from afar without touching or drilling into them. This would be achieved through the use of radioactive muons, or cosmic particles, infrared thermography, photogrammetry, scanning and 3D reconstruction by international researchers from three major universities: the Faculty of Engineering at Cairo University, the Université Laval in Quebec and the Nagoya University in Japan.

 “The scientific ScanPyramids Project is an unprecedented, large-scale project and will begin early in November,” Minister of Antiquities Mamdouh Eldamaty told Al-Ahram Weekly on the fringes of a press conference held on Sunday in Cairo. He explained that the first phase of the project would focus on four pyramids from the Fourth Dynasty: the Bent and Red Pyramids of Snefru at the Dahshur Necropolis and the Khufu and Khafre Pyramids on the Giza Plateau.

“We selected these pyramids to be in the project’s first phase not because they are Fourth Dynasty masterpieces, but because they hide many secrets,” Eldamaty said, asking how it had been possible to construct Khufu’s Pyramid on the Giza Plateau, which contains 2.5 million blocks of stone weighing five million tons in only 25 years.

Why does the Bent Pyramid of Snefru in Dahshur have a different structure from the king’s second pyramid at the same necropolis? Why does the Bent Pyramid have two doors and two burial chambers? “The various explorations conducted in the past using less sophisticated means than today have resulted in strange images that could correspond to hidden chambers in these structures,” he pointed out, adding that the high technology methods to be used today were non-invasive and non-destructive.

Eldamaty said that two infrared thermography missions would establish a thermal map of the pyramids to reveal differences in density. One would be conducted by expert Jean-Claude Barré, while the other, running for at least a year, would be led by the Université Laval in Quebec.

“Their goal is to identify if there are any voids behind the facades of the pyramids,” he said. Two missions using muon radiography also aim to verify and accurately visualise the any unknown structures within the monuments. These techniques are being developed in Japan by teams from the country’s High Energy Accelerator Research Organisation (KEK) and Nagoya University.

“The team is to work for a year trying to crack the codes of the pyramids. I am announcing 2016 as the “Year of the Pyramids,” Eldamaty told the Weekly, adding that the ScanPyramids Project had already been approved by the permanent committee of the Ministry of Antiquities and had obtained all the necessary permissions from the concerned authorities.

“The infrared and muon technologies will also be used to look for a possible hidden chamber in king Tutankhamun’s tomb, which may be the burial place of queen Nefertiti, as British Egyptologist Nicholas Reeves proposed in his recent theory,” Eldamaty said.

He said that archaeologists have not discovered the mummy of the legendary queen Nefertiti, and Reeves, who was in Luxor in September to probe his theory, believes a hidden door in Tutankhamun’s tomb could conceal her burial place. The permanent committee for Ancient Egyptian antiquities at the ministry has already approved using radar to search within the boy king’s tomb, but the search is still awaiting security clearance.

Mehdi Tayoubi, president of the HIP Institute, a co-initiator and coordinator of the ScanPyramids Project, described it as “very important” because it is a mix of the arts, science and technology in an attempt to use new perspectives and approaches to find solutions to heritage issues. “Our desire is to form an international team of experts and then to discuss the theoretical and technological approaches that could be used to test the archaeological reality on the ground,” he said.

Many previous missions have attempted to unravel the mysteries of the pyramids, he said, and even if they had been unsuccessful, they had helped advance knowledge. For example, 30 years ago the French EDF Foundation had detected a density anomaly in Khufu’s Pyramid. “Our goal is to make our contribution and to prepare, in all humility, the path for future scientific research missions,” he said.

Former minister of education Hani Hilal who leads the team from the Faculty of Engineering pointed out that until now many theories have been proposed either to explain the construction of the pyramids or their structural anomalies, but nothing has yet been proved. “Now through using state-of-the-art techniques we can get concrete results that archaeologists and Egyptologists will interpret to test which theory is correct or acceptable,” Hilal told the Weekly.

He said that when people asked him about the purposes of participating in such a project as an engineer and not an archaeologist, he answered that “I and the team of engineers are participating in the project because we are physicists and engineers and the pyramids were built by engineers, so we will be better able to understand our ancient Egyptian counterparts. But we would not be able to do so without the cooperation of the archaeologists.”

The ScanPyramids Project was in the direct line of what he had done 30 years ago in 1982, when, in collaboration with a Franco-Egyptian mission from the Faculty of Engineering at Cairo University and the Ecole des Mines in France, he had helped carry out scientific and technological studies on ancient monuments in Egypt. “We were the pioneers in the domain,” Hilal said, adding that the work had led to the creation of the Engineering Centre for Archaeology in Egypt, which had become a centre of excellence in the region.

In 1986, Hilal had also participated in studies using a micro-gravimeter carried out on Khufu’s Pyramid. But he said that the surveying technique used at that time was not fully professional like the current one, so results were not achievable. But the survey helped people to understand more about the pyramids.

“With the current mission and advanced technology we may not be able to resolve all the mysteries of the pyramids, but we are progressing by testing new processes. No doubt we will obtain good results about what the pyramids hide behind their massive blocks of stone,” Hilal said, adding that if the techniques work they could also be used elsewhere.

   Infrared thermography
MATTHIEU Klein who is in charge of thermographic data acquisition in situ said that the infrared thermography work implemented by Jean-Claude Barré was one of the most promising methods to try to understand what lies within the monuments.

The technique is based on a physical law that says that all materials emit radiation as a function of their temperatures, which can be measured by digital cameras equipped with special sensors. These cameras generate images in which each colour corresponds to a given temperature.

The technique, he said, is widely used to reveal heat losses in poorly insulated homes, and it allows the presence of defects in buildings to be located. “Thus, a cold air current will be represented in blue, whereas a heat source will be shown in red. These specialised cameras are also capable of quantifying the emissivity of materials,” Klein said.

For example, under the sun’s heat the interior of a white car will be cooler than the interior of a black one. Similarly in identical sunlight, granite and limestone will not return the same temperature. “The principle is simple, but its implementation requires sophisticated instruments and highly experienced operators,” Klein said.

In this project, the goal is to realise a true thermal map of the Dahshur and Giza Pyramids. This will be done through making thermal images of the four sides of each pyramid three times throughout the day in order to read the amount of energy it gains when absorbing the sun’s heat. The first time will be half an hour before sunrise when the monument has evacuated maximum energy during the night. The second time will be at noon, and the third will be in the evening. In a few days, said Klein, hundreds of thousands of images will be recorded and compared with each other by a computer programme.

The differences in emissivity will allow scientists to investigate the surface of stones that are now the same colour due to bad weather, sand and pollution. “But what interests us most are potential cold spots on the surface, which could reveal cavities, rooms or hallways within the monuments,” he said.

  Muon detection
RESEARCHER Kunihiro Morishima of Nagoya University in Japan has invented an advanced kind of negative film like that used in old cameras that could help detect muons as part of the scanning project.

Morishima explained that muons come from the upper layers of the earth’s atmosphere, where they are created from collisions between cosmic rays and the nuclei of atoms in the atmosphere. They then fall to the ground at nearly the speed of light.

“Like the X-rays that pass through our bodies allowing us to visualise our skeletons, these elementary particles like heavy electrons can very easily pass through any structure, even large and thick rocks, such as mountains,” Morishima told the Weekly. He said that detectors, placed at appropriate places, allow scientists to discern void areas that the muons have crossed from denser areas where some of them are absorbed or deflected.

“The challenge of this technique is to create highly sensitive detectors and then to accumulate enough data over several days or months to emphasise the contrasts,” he said. He added that in the case of applying the technique to the pyramids it could take from 90 to 120 days.

“It is the first time that muon radiography has been used on a monument, but it is now frequently used for the observation of volcanoes,” Morishima asserted. He explained that more recently KEK in Japan had also developed a detection approach based on electronic scintillators, which are resistant to nuclear radiation unlike chemical emulsions, in order to scan inside the Fukushima nuclear plant.

A laboratory to develop and analyse the images captured by the muon radiography has been established on the Giza Plateau by the Japanese team. “This laboratory is the first to be built and equipped outside Japan,” Morishima said.

   Photogrammetry and lasers
RESEARCHER Yves Ubelmann said that in parallel to the Pyramids exploration missions, the Iconem Company would carry out a photogrammetry campaign using drones and laser scanners to rebuild the Giza Plateau and the site of Dahshur in virtual form with their monuments in 3D using unique centimetre precision. “This campaign is entirely dedicated to the advancement of knowledge. Sharing and transfer are the key words,” Ubelmann said.

The algorithms used by Iconem were developed by the French National Institute for Computer Science and Applied Mathematics, which is already working in Pompeii and in Syria and Afghanistan to help restore threatened sites. Ubelmann told the Weekly that Iconem would use drones with wings like helicopters in order to collect the data.

The drones with wings would allow data to be collected from large areas in the reconstruction of the pyramids’ environment with resolution of up to five cm. Details of this micro-topography would also give clues about the position or shape of unexcavated buildings.

The second type of drones look like helicopters, and though they have less autonomy they can hover. They can take images metres away from the monuments, and the results are detailed to a centimetre scale. “This high definition will provide geometric information about especially the alignment and assembly of the blocks, but also the texture and possibly traces of tools or construction work,” Ublemann confirmed.

“Photogrammetry allows us to work and combine the different scales exploited in the same digital model and propose a global interpretation of the sites,” he concluded, adding that to complete the mission the team would also perform laser analysis inside the monuments in areas where photogrammetry cannot operate.

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