The crater in the photo is known as Airy 0, a 500-meter-wide depression that lies inside the much larger Airy crater, which is about 43.5 km wide. The newly released image was taken on September 8, 2021 using the High-Resolution Imaging Science Experiment camera on NASA’s Mars Reconnaissance Orbiter.
In 1884, astronomers initially chose the larger Airy crater to designate the “principal meridian” – a line of zero degrees of longitude where east intersects west, NASA said.
Airy craters are named after the British astronomer Sir George Biddell Airy, who built a telescope at the Greenwich Royal Observatory and was the first to spot the massive crater.
Astronomers chose Airy to designate the Martian prime meridian because at the time it was large enough to be seen with telescopes.
“But with the advent of higher-resolution photographs, a need has arisen for a more compact object,” NASA officials wrote. The scientists chose Airy-0 to replace Airy as the prime meridian marker because it was the right size and did not require drastic changes to existing maps, the report said.
Airy Crater is located in a region known as Sinus Meridiani, which translates to “Middle Bay” according to NASA.
The glowing ridges in the crater are known as transverse aeolian ridges (PEGs), said Abigail Freiman, planetary scientist and associate scientist for NASA’s Curiosity Data Science Project. “PEG is a feature that we commonly see in craters and other depressions on Mars,” she added.
According to Freiman, the ridges are formed from sand dunes that are covered with a thin layer of dust. The dust covering the ridges on Airy-0 is most likely hematite, an iron oxide mineral that is abundant in the surrounding region and gives the ground its gray color in the photograph. The hematite dust is likely reflective, making the PEG stand out from the rest of the crater.
This is not the first time strange lines have been observed in Martian craters.
On March 30, the European Space Agency (ESA) released images of a pair of craters taken by ESA’s Mars Express orbiter. In one of these craters, traces of “brain relief” were found – ripples that are remarkably similar to the ridges of the human brain. However, these lines were caused by ice deposits, not PEGs, the paper says.
In June 2021, the ExoMars Trace Gas Orbiter, a joint mission between ESA and the Russian space agency Roscosmos, took pictures of an obscure crater with concentric rings “like trees”. Again, these features were most likely caused by the ice from the comet that gave birth to it, and not by the PEG.
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