 Modifications to Ranger 5 included a backup timer to ensure continued operation of the telemetry system if the main computer failed, an additional nitrogen bottle to the attitude control system to reduce gas pressure, and an additional pyrotechnic igniter for the midcourse correction engine.Most importantly, extra diodes and fuses were added to the electrical lines to prevent another short from occurring.Ranger 5 was heat-sterilized like Rangers 3-4 had been, so as to prevent unintended contamination of the Moon with Earth microbes.