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While the HDEV collects beautiful images of the Earth from the ISS, the primary purpose of the experiment is an engineering one: monitoring the rate at which HD video camera image quality degrades when exposed to the space environment (mainly from cosmic ray damage) and verify the effectiveness of the design of the HDEV housing for thermal control.
The four cameras of the HDEV experiment are oriented in different directions and with different views relative to the ISS travel direction. They are in positioned, 1 looking forward, 1 looking nearly straight down, and 2 looking back. This provides several different viewing angles to the viewer.
The cameras are programmed to cycle from one camera to the next, and only one camera can work at a time. As they cycle, each camera must turn off and the next camera turn on before the HD video starts, taking about 8 to 10 seconds to change. Through this cycling, comparable data can be collected on each camera; while also providing, as a bonus, different Earth viewing perspectives.
The University of Bonn in partnership with the German Space Agency (DLR) is implementing the "Columbus Eye" program based on the HDEV streaming video. A webpage is in place (http://columbuseye.uni-bonn.de/ in German) that incorporates the HDEV UStream video and describes the Columbus Eye project, which will leverage ESA astronaut Alexander Gerst educational activities in space.
For all questions regarding HDEV, please contact the HDEV Principal Investigator, Susan Runco.