Page:Concepts for detection of extraterrestrial life.djvu/22

12 face plate are scanned by a beam of electrons which differentiate these light and dark areas by their electrical resistance. The scan lines are converted into electrical signals, highly amplified, converted to a frequency-modulated signal, sent to a 60-watt transmitter, and received on Earth. Direct mounting and use of this system on a capsule on the surface of Mars is not now possible. Nevertheless, the Ranger VII photographs of the Moon underscore the potential of the system as soon as technology permits its application to the planets.

A more sophisticated use of television cameras is illustrated by the microscope-television combination described in the next chapter.