Earth Observations taken by the Expedition 15 Crew

ISS015-E-27232 (5 Sept. 2007) --- North and South Platte Rivers, Nebraska are featured in this image photographed by an Expedition 15 crewmember on the International Space Station. Lake McConaughy and thousands of rectangular tan and green agricultural fields of western Nebraska and northeastern Colorado dominate this oblique scene. The crewmember that shot this view was looking towards the east-northeast, focusing on the thin, green lines of the floodplains of the North and South Platte rivers. These join to form the Platte River near upper right. The Platte river system has determined transportation routes for centuries. Modern Highway 80 follows the North Platte and Highway 76 the South Platte. The presence of transport routes and rivers--as sources of water in a semiarid region--in turn determine the location of towns: the city of North Platte stands out as a light gray area on the floodplain at the confluence of the North and South Platte rivers, as do two smaller towns, Gothenburg and Cozad, further downstream (top right). The distribution of cropland visible in this image is also interesting to geographers. The flattest surfaces are easiest to farm and have the highest areal density of farmed fields. These flat surfaces lie on the river floodplains, but are also present on the higher surrounding surfaces. Between the heavily cultivated land in the river floodplain and the uplands is a strip of rough country that is difficult to farm. As a result, it stands out as a gray strip running parallel to the green croplands of the floodplains. The famous Nebraska Sand Hills, recognizable by their characteristic scalloped texture north of the lake at center, are a hummocky dune field (now vegetated) and are thus also largely devoid of fields. Westernmost Nebraska has been abnormally dry in the last three months--covering the time when this image was taken (Sept. 5). This water deficit can be seen on the image in terms of grass cover health: browner (drier) surfaces occupy the dry regions (lower left), and greener (moister) surfaces appear further east (right).