 The Atlas-Agena combination malfunctioned four out of the six times that NASA had launched it and every booster that was delivered to Cape Canaveral required modifications or repair work before it could fly.Moreover, in the year between Ranger 1 and Mariner 2, there had been no improvement whatsoever in the quality control of the Atlas-Agenas.Since Ranger launches had been delayed before by booster problems, technicians rushed to make sure nothing of the sort would delay Ranger 5's mission.