Editing Mariner 5 (section)

==Venus flyby==
Mariner 5 flew by Venus on  October 19, 1967,  at an altitude of {{convert|3990|km|mi|sp=us}}. With more sensitive instruments than its predecessor [[Mariner 2]], Mariner 5 was able to shed new light on the hot, [[cloud]]-covered planet and on conditions in interplanetary space.

Radio occultation data from Mariner 5 helped to understand the temperature and pressure data returned by the [[Venera 4]] lander, which arrived at Venus shortly before it. The ''Venera 4'' and ''Mariner 5'' data was subsequently analysed together under a combined Soviet–American working group of [[COSPAR]] in 1969,{{r|sagan-1969|conf1}} an organization of early space cooperation.<ref name=nasa1/> With the data of these missions, it was clear that Venus had a very hot surface and an atmosphere even denser than expected.

The operations of Mariner 5 ended in November 1967 and it is now defunct in a [[heliocentric orbit]].