On May 5 , 1961 which astronaut became the first American in space aboard " Freedom 7 " , launched by a Redstone booster on a 15 - minute ballistic ( suborbital ) flight ?
In 1959 , Shepard was one of 110 military test pilots selected by their commanding officers as candidates for the newly formed National Aeronautics and Space Administration 's Project Mercury , the first US manned space NASA flight program .