 The instrument package floated in a layer of freon within the balsawood sphere.The radar altimeter would be used for reflectivity studies, but was also designed to initiate capsule separation and ignite the retro-rocket.Ranger 5 was scheduled for launch in June 1962, but NASA instead decided to fly the Mariner Venus probes (basically modified Block I Rangers) first which gave more time to work out problems with the spacecraft.