Yuri Alekseyevich Gagarin. Wikipedia photo by Mil.ru, CC BY 4.0,

Today marks the 65th anniversary of the first human flight into space by Soviet Cosmonaut Yuri Gagarin aboard the Vostok 1 spacecraft, on April 12, 1961.  Vostok 1 was Gagarin’s only space flight.  Soviet officials were worried that a hero of the Soviet Union might die in a mishap in a later flight, so they grounded him.  Ironically, he was killed in 1968 at the age of 34, in a crash of the MIG fighter he was piloting in a training mission.