Kachina Chasma

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Voyager 2 image of Ariel. Kachina Chasma can be seen in the upper part of the image.

Kachina Chasma (or Kachina Chasmata) is the longest canyon on the surface of the Uranian moon Ariel. Its name comes from a spirit in Hopi mythology.[1] The 622 km long and 50 km wide chasmata is a system of normal faults running from the north-west to south-east. The faults bound down-dropped crustal blocks forming structures called graben.[2] The canyons cut the cratered terrain, which means that they were formed at a relatively late stage of the moon's evolution, when the interior of Ariel expanded and its ice crust cracked as a result.[3] The floor of Kachina Chasma is not visible on the images obtained by the Voyager 2 spacecraft in January 1986;[2] thus, whether it is covered by smooth plains like the floors of other Arielian graben is currently unknown.[3]

During the Voyager 2 flyby in 1986 the northern hemisphere of Ariel was not illuminated by the Sun because the spacecraft arrived during a southern solstice on Uranus. Nevertheless, because it was still illuminated by light reflected from Uranus, scientists using advanced processing methods were able to detect some details in the dark hemisphere. These analyses revealed a continuation of Kachina Chasmata into the dark hemisphere, possibly as far as to the opposite limb.[4][5] As the total length of Kachina Chasmata appears to be 1800–2200 km, it may be comparable to Ithaca Chasma on Tethys.[6]

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