Venera V V V and V entry probes

These fourth-generation Venus probes were used for four consecutive Venus launch windows from 1967 to 1972. In spite of the failure of three of the eight craft to leave Earth orbit (the result of ongoing problems with the launcher's upper stage) and the loss of the Venera 4, 5 and 6 probes before they reached the surface, these probes were the first successful planetary entry probes. They returned data on the atmospheric temperature and pressure profiles, composition, dynamics, light levels and surface composition, despite the highly restrictive data rate of 1 bit s_1.

Following on from the 3MV entry probes, these probes were 10 cm larger in diameter than their predecessors, and became progressively more sophisticated and optimised to survive the Venusian temperature and pressure environment all the way down to the surface. Veneras 4-7 entered on the night side, Venera 8 on the day side. They eventually made way for a fifth generation of Veneras with greater payload capacity, surface capability and data rate. Venera 8 was still essentially an atmospheric probe; Venera 9 was to be a true lander. On Venera 8, however, to ensure that surface communication would still be possible if the probe did not come to rest in an upright position, an additional, ejected antenna was provided. Tethered to the probe, it contained a tilt switch to activate whichever face of the antenna landed uppermost. Venera 8's main transmitting antenna was also different. This was a result of the probe's planned landing near the dayside terminator - the Earth was much lower above the horizon and so an antenna having a beam pattern with higher gain at low elevations was chosen.

The first figure below (16.3) depicts the design of the Venera 4 probe (and its lost twin on Cosmos 167); Veneras 5 and 6 would have been almost identical in external appearance, with the possible exception of an aperture on 5 and 6 for the 'airglow photometer'. The second and third figures (16.4 and 16.5) depict Veneras 7 and 8, respectively (and of course their lost 'twins').

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