In 1971 which USA space probe was first to orbit another planet

Mariner 9
Mariner 9 (Mariner Mars '71 / Mariner-I) was an unmanned NASA space probe that contributed greatly to the exploration of Mars and was part of the Mariner program.

Mariner 9 was launched toward Mars on May 30, 1971 from Cape Canaveral Air Force Station and reached the planet on November 14 of the same year, becoming the first spacecraft to orbit another planet – only narrowly beating the Soviets' Mars 2 and Mars 3, which both arrived within a month.

After months of dust storms it managed to send back clear pictures of the surface.

Mariner 9 returned 7329 images over the course of its mission, which concluded in October 1972.

Read more...https://en.wikipedia.org/wiki/Mariner_9