National Geographic : 1988 Nov
The view from 40,000 feet aboard a Learjet was "utterly hazeless, like the surface of the moon," said aerial photographer Kurt Keller (above). The camera viewfinder zeroes in on Ever est (left). Project leader Washburn (below, atfar left) scrutinizes the new map with a team of Swiss surveying experts in Berne. Mapping Everest The most recent survey of the high Himalaya, a project be gun in 1984 under the aegis of Boston's Museum of Sci ence and the National Geographic Society, mapped 380 square miles of the Everest region. The resulting ten large-scale (1:10,000) maps became blueprints for the shaded-relief map on this issue's supplement. It all began with the Great Trigo nometrical Survey of India. In the late 1840s British surveyors took the odolite sightings of Himalayan peaks from six geodetic stations along a tri angulation chain in northern India (diagram, right, at bottom). In 1852 the position and elevation of Peak XV, as Everest was then known, were determined. It took until 1954, however, to establish today's accepted height for Ever est-29,028 feet (8,848 meters). Both this figure and the peak's po sition were crucial to the new sur vey, which used Everest as the main ground-control, or reference, point. Crucial too were British, Austrian, and Chinese topographic maps made between 1921 and 1975 by standard ground surveying methods and low altitude aerial photography. Stereophotography from space added a new element. On December 2, 1983, the space shuttle Columbia passed over Everest at an altitude of 156 miles. A high-resolution West German aerial-survey camera made many overlapping infrared images, each covering 13,800 square miles. At a Swiss photogrammetry center the locations of peaks and other points on the European and Chinese maps were compared with corre sponding features on the stereo photographs. A computer identified map errors and enabled the selection of a hundred new ground-control points used to anchor 160 overlap ping vertical aerials taken on December 20, 1984, from a Learjet flying at 40,000 feet. The pictures re veal a clarity and richness of detail borne out on the maps created from them-far beyond the vision of the earthbound 19th-century surveyors.