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 ?
The longest single human spaceflight is that of Valeriy Polyakov , who left Earth on 8 January 1994 , and did not return until 22 March 1995 ( a total of 437 days 17 hr.