Space electronics: Automatic checkout for missions to Mars: Unmanned extraterrestrial landings call for reliable premission testing of complex guidance and communications systems

In carrying out the extraterrestrial unmanned landing-a more difficult feat than close-orbit of flyby missions-Viking will employ two radar systems (one for determining altitude, the other for such parameters as velocity, drift, and attitude), and two communications systems (one as a direct link from both orbiter and lander to Earth, the other a one-way relay link from lander to orbiter). To obtain maximum reliability from these critical systems, sophisticated automatic checkout equipment has been developed by Martin Marietta, prime contractor for the Vicking program.