Space systems as marine geologic sensors

Abstract

Abstract Space systems that provide measurements applicable to marine geologic studies can be divided into two categories: ground- based observations of artificial and natural satellites and stars, and satellite-borne sensors that make visual, infrared, and radiofrequency measurements of the ground and ocean. The ground- based measurements provide information on plate motion and intraplate deformation, as well as long-wavelength (> 1000 km) information about the earth’s gravity field useful in tests of hypotheses of plate motion. The satellite-borne observations provide information on short-wavelength (<100 km) variations in the gravity field that correlate with seamounts and other geologic features, observations of terrestrial lineations and other surface features, limited information about ocean depth in shallow areas, and direct observations of sedimentary plumes and plankton in surface water. Satellite-borne instruments also yield indirect data relating to sedimentary processes and plankton productivity and dispersal through observation of ocean currents and their meanders, rings, ocean surface temperature, icebergs and sea ice, surface waves and internal waves that affect these processes. Satellites also provide a valuable service in collecting and relaying data from remote fixed stations and from drifting buoys and also determine the position of buoys so that current patterns can be determined. Long-wavelength features of the earth’s gravity field are determined from laser range or from radio frequency Doppler observations of artificial satellites. Doppler observations are an indirect form of range measurements, since the maximum rate of change of the Doppler measurements within a pass varies inversely with the range between the transmitter and receiver