Thirty-five years ago today — September 21, 1974 — Mariner-10 made its second flyby of the planet Mercury.
(Mosaic of Mariner-10’s images of Mercury. NASA image from http://apod.nasa.gov/apod/ap980906.html.)
Mariner-10 was the first spacecraft to examine Mercury up close. Today the MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) spacecraft is studying Mercury, and its next flyby is scheduled for next week. Read more about MESSENGER here and here.
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