Illustration of a Venera probe descending to the surface of Venus. At top right the probe is released from its service spacecraft, which remains in orbit to receive and transmit data from the probe. The probe enters the Venusian atmosphere and deploys its parachutes (upper left). At an altitude of around 50 kilometres its outer shell and parachute are jettisoned and airbraking is used to slow its descent to the surface. Between the 1960s and 1980s the USSR launched 16 probes to Venus, 13 of which successfully entered the Venusian atmosphere. The probes recorded and transmited data about atmospheric pressure, temperature and chemical composition, along with photographs and sound recordings.