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Gravimetric shear, also known as "grav shear" or "spatial turbulence", is a type of gravimetric distortion and a shear force commonly associated with certain astronomical phenomena such as stellar clusters and neutronic storms, that can pose a threat to starships. Shear is caused by localized, extreme differences in the gravitational coefficient that produces great stress on matter that crosses the point of localized difference. Gravimetric shear might be characterized by a shearline.

Enterprise NX-01 encountered severe grav shear in 2152 when it passed through a class five neutronic storm. (ENT: "The Catwalk")

Protostar clusters, such as the Argolis Cluster, are generally regarded as impassible to spacecraft due to their intense gravimetric shear. In 2374, Captain Benjamin Sisko planned an attack on a Dominion sensor array through the Argolis Cluster. He was confident that Jadzia Dax, having studied protostar clusters, would be able to navigate the USS Defiant around the gravimetric shear. (DS9: "Behind the Lines")

In 2375, a Class 2 shuttlecraft from the USS Voyager was caught in the gravimetric shear from a proto-nebula, necessitating the evacuation of those aboard. (VOY: "Drone")

Later that year, Voyager experienced heavy gravimetric shear from a subspace sinkhole that had earlier swallowed one of its shuttlecraft. (VOY: "Gravity")

In 2381, the Yosemite, a Type 6A shuttlecraft from the USS Cerritos, was caught in a gravimetric shear caused by a gravity well, resulting in a crash landing on a desert planet. The shuttlecraft was abandoned and never salvaged, instead being replaced with the Yosemite II. (LD: "Where Pleasant Fountains Lie", "Grounded")

In the first draft script of ENT: "Fusion" (which had the working title "Equilibrium"), indications of gravimetric shear (as well as a few pockets of turbulence) were detected by Enterprise as existing in the Arachnid Nebula, while the ship prepared to head into the nebula. When Captain Archer asked Lieutenant Reed if the vessel could avoid them, Reed replied, "Gravimetric shear is notoriously unpredictable," which Archer admitted wasn't the answer he had been hoping for.

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