'''Mercury 3''' or variants may refer to:
* Mercury-Redstone 3, a spacecraft of Project Mercury * Mercury(III), an unknown compound of the element Mercury * Mercury III, a version of the Blackburn Mercury early British aircraft * Mercury III, a 1929 version of the Bristol Mercury aircraft engine
==See also== * Mercury (disambiguation) *Mercury-Redstone 3, the first U.S. human spaceflight, 1961 *Mercury-Atlas 3, a 1961 unmanned space flight
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