The first one was destroyed shortly after launch when the vehicle carrying it steered off course.
The first one was destroyed shortly after launch when the vehicle carrying it steered off course. The third one included a radiation detector to measure the Van Allen belts and similar Martian phenomena, while numbers 6 and 7 were launched with the purpose of searching for conditions suitable to extraterrestrial life 2  on Mars in flyby mode. Number 8 failed outright, so number 9 accomplished both its own objectives and those of 8, while the tenth and last one demonstrated Hadley-type circulation in the Venusian atmosphere.  All of these were, FTP, spacecraft from what nautically named NASA program, designed to observe Mars and Venus in flyby?
The first one was destroyed shortly after launch when the vehicle carrying it steered off course.
Mariner