Unique characteristics of ERTS

The manned spaceflights have demonstrated what film cameras can do in space and they could provide a data source from which maps would be one of the principal products. ERTS was not defined with mapping as one of its principal objectives, but with ERTS-1 in orbit certain unique characteristics or advantages of the electronic transmission (TV) earth sensing system become apparent to the mapmaker. Six of the more obvious advantages over aircraft and satellite film systems are: (1) long life and coverage; (2) near real time; (3) orthogonality; (4) radiometric fidelity; (5) extension into the near IR wavelengths; and (6) extension into the thermal wavelengths.