The Apollo 8 spacecraft consisted of a command module similar to Apollo 7 except that the forward pressure and ablative hatches were replaced by a combined forward hatch, which would be used for transfer to the Lunar Module on later missions. The spacecraft mass of 28,817 kg is the mass of the CSM including propellants and expendables. A Lunar Module was not used on the Apollo 8 mission but a Lunar Module Test Article which was equivalent in mass (9027 kg) to a Lunar Module was mounted in the spacecraft/launch vehicle adapter as ballast for mass loading purposes. The spacecraft was launched on December 21, 1968 at 12:51:00 UT (7:51 a.m. EST), and was placed in a 190.6 km x 183.2 km Earth parking orbit with a period of 88.2 minutes and an inclination of 32.51 degrees. At 15:41:37 UT a third-stage burn injected the Apollo spacecraft into trans-lunar trajectory. Orbit insertion took place on 24 December at 09:59:20 UT into an elliptical 310.6 km by 111.2 km lunar orbit. Two orbits later a second burn placed Apollo 8 into a near-circular 110.4 by 112.3 km orbit for eight orbits. The trans-earth injection burn took place on 25 December at 06:10:16 UT after a total of 10 lunar orbits. Apollo 8 splashed down in the Pacific Ocean on 27 December 1968 at 15:51:42 UT (10:51:42 a.m. EST) after a mission elapsed time of 147 hrs, 0 mins, 42 secs. The splashdown point was 8 deg 7.5 min N, 165 deg 1.2 min W, 1,000 miles SSW of Hawaii and 5 km (3 mi) from the recovery ship USS Yorktown.