Mariner 5

Mariner V, Mariner Venus 1967

Mission Profile

Mariner 5 (Mariner Venus 1967) was a NASA spacecraft launched on 14 June 1967 aboard an Atlas LV-3 Agena-B to conduct a close flyby of Venus and study its atmosphere, magnetic field, and radiation environment. Originally built as a backup for Mariner 4, Mariner 5 was refurbished and repurposed for the Venus mission after Mariner 4 successfully completed its Mars flyby. During its 4,000-km flyby of Venus on 19 October 1967, Mariner 5 confirmed that Venus has no significant magnetic field and provided radio occultation measurements that established atmospheric pressure at the surface of approximately 75-100 atmospheres. These findings were far higher than previously believed and helped establish Venus as a hellish world utterly unsuited for life.