Deimos -- Mars' smallest moon -- has only two named features: the Swift crater and the Voltaire crater. Based on the Gazetteer of Planetary Nomenclature, their names were approved in 1973.

Given the size of these craters, I assume they weren't discovered until the space age. Perhaps during a Mariner flyby? When were these craters first discovered?


1 Answer 1


NASA says about the Mariner 9:

The spacecraft also provided the first closeup pictures of the two small, irregular Martian moons: Phobos and Deimos.

This must have happened somewhere between November 14th, 1971 and October 27th, 1972. Here is a picture from January 27th, 1972 which shows them:

enter image description here

FWIW, the only other spacecraft to reach Mars between then and 1973 was the Russian Mars 2.


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