MARINER

any of a series of unmanned U.S. space probes sent to the vicinities of Venus, Mars, and Mercury. Mariners 2 (1962) and 5 (1967) passed Venus within 22,000 miles and 2,500 miles (13,700 and 1,500 kilometres), respectively, and made measurements of temperature and atmospheric density. Mariners 4 (1965), 6 and 7 (1969), and 9 (197172) obtained striking photographs of the Martian surface and made significant analyses of the atmosphere of that planet. Mariner 10 (197375), which flew by Mercury three times, passed within 200 miles of the planet on its third pass and radioed back to Earth the first close-up pictures of the surface, as well as analyses of the atmosphere and magnetic field.