Spiral Eddies

Indian Ocean Front

Indian Ocean Front

S08-42-2091 (250 mm)
Flight STS-8; 18S, 40E, 4 Aug 1985

The enthusiasm generated by the discovery by the crew of STS-7 of spirals in the Southern Hemisphere spread over to the crew of STS-8, scheduled for August 1985. The mission would begin with the first night launch, and the crew would, therefore, have excellent viewing conditions in the Southern Hemisphere, where they could search for more clockwise spiral eddies.
    During the first two days of the mission, the crew commander reported that the southern oceans were "essentially featureless." By the third day, the ocean had changed. The commander reported to Mission Control that, "I'm looking at the most complexed ocean imaginable for as far as I can see." The entire southern Indian Ocean, Tasman Sea, and southwestern Pacific Ocean were covered with spiral eddies and remained so for the rest of the mission.
    With a 250-mm lens, the crew began taking overlapping pairs of photographs that showed the spiral eddy field in great detail. The slicks on the sea surface were basically streamlines of the flow into and between eddies.
    At first, there was some speculation that the features were the result of local wind action over the sea, but other data indicated that the eddies extended to depths of several tens of meters. They were, therefore, integral parts of the dynamics of the upper ocean. Other data, skimpy at first, showed that the streamline slicks did indeed flow into the eddies and at speeds greater than those of the surrounding water.

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