 At 1 : 00 pm EST ( 1800 GMT ) on January 27 , first Grissom , then Chaffee , and White entered the Command Module fully pressure @-@ suited , and were strapped into their seats and hooked up to the spacecraft 's oxygen and communication systems . Grissom immediately noticed a strange odor in the air circulating through his suit which he compared to " sour buttermilk " , and the simulated countdown was held at 1 : 20 pm , while air samples were taken . No cause of the odor could be found , and the countdown was resumed at 2 : 42 pm . The accident investigation found this odor not to be related to the fire . 
