NASA unveils photo. ISS astronaut captures "Ghoulish Face"
The NASA Earth Observatory occasionally publishes stunning photographs from space. This was the case with a photo shared by the institution on October 31. Although the picture was taken by one of the ISS astronauts in early February, it only recently gained prominence. It features the Trou au Natron, a volcanic caldera in northern Chad, which presents an unusual appearance when viewed from the International Space Station.
9:55 AM EDT, November 3, 2023
As detailed by NASA, an ISS astronaut took the photo on February 12, 2023, using a standard digital Nikon D5 camera. The photograph highlights an approximately 3281-foot-deep crater with a diameter varying from 3.7 to 5 miles. It includes a soda lake, Trou au Natron, situated in northern Chad. Remarkably, from the ISS, which orbits approximately 249 miles above Earth, this natural formation resembles a "ghostly face staring back".
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The face's outline is partially formed from shadows cast by the edges of the caldera. The "eyes" and "nose" of this eerie visage are slug cones created around volcanic vents. The mouth's surrounding white area is a mineral shell comprised of natron, which NASA describes as a mix of sodium carbonate, sodium bicarbonate, sodium chloride, and sodium sulfate. This shell is formed "when hot spring water accumulates on the surface, evaporates, and subsequent mineral-rich steam rises from the surface of the geothermally active area".
"IFL Science" service notes that Trou au Natron is nestled in the Tibesti Mountains, the Sahara's highest mountain massif, at an elevation of 8038 feet. The area is one of the Earth's most remote and isolated regions, making its comprehensive exploration a challenging task. Although the volcano is extinct, the timing of its last eruption remains unknown. Thus, it's still a treasure trove of geological, morphological, and cultural mysteries.
The enigmatic history of Trou au Natron was partially unraveled by an analysis conducted on rock samples and fossils gathered in the 1960s. According to NASA, these revealed that around 14,000 years ago, Trou au Natron was a glacial lake hundreds of meters deep. Furthermore, a 2015 expedition, led by German researcher Stefan Kröpelin, found fossilized aquatic algae, suggesting that their origination could date back to approximately 120,000 years ago. Satellite observations of the region are instrumental in providing additional information about Trou au Natron.
