 Apollo lunar missions would begin with a nominal 100 @-@ nautical @-@ mile ( 185 km ) circular Earth parking orbit . Apollo 8 was launched into an initial orbit with an apogee of 99 @.@ 99 nautical miles ( 185 @.@ 18 km ) and a perigee of 99 @.@ 57 nautical miles ( 184 @.@ 40 km ) , with an inclination of 32 @.@ 51 ° to the Equator , and an orbital period of 88 @.@ 19 minutes . Propellant venting increased the apogee by 6 @.@ 4 nautical miles ( 11 @.@ 9 km ) over the 2 hours , 44 minutes and 30 seconds spent in the parking orbit . 
