Saturn S-IVB-503N

  1968-118B

---

The third Saturn V was launched on 1968 Dec 21. Its third stage was S-IVB-503N; S-IVB-503 was destroyed in a ground accident, and the stages already constructed at that time were renumbered with the `N' designation - thus the original 504 became 503N, etc.

In Feb 1968 the SA-503 was erected with SLA-10, LTA-B and BP-30. It was then decided to fly the mission with a crew using CSM 103 and LM-3; and then in Aug 1968 with CSM-103 and LTA-B/SLA-11A.

The J-2 engine reignited at 1541:37 to insert Apollo 8 on a translunar trajectory. The Apollo spaceship separated at 1611:59. The stage then released its residual propellants, changing its trajectory to a lunar flyby. 503N reached the Moon on Dec 24, flying past at 1225 km on its way to solar orbit, gaining 1.46 km/s.

S-4B-503N
Date	Time	Event	Orbit
1968 Dec 21	1251:00	Launch of SA-503
1968 Dec 21	1253:06	S-IC center engine cutoff
1968 Dec 21	1253:33	S-IC outboard engines cutoff
1968 Dec 21	1253:34	S-IC-503 separation, altitude 80.5 km
	1254:04	Interstage sep
1968 Dec 21	1254:08	LES separation
1968 Dec 21	1259:44	S-II-3 separation
1968 Dec 21	1259:45	S-IVB burn ignition
	1259:57	Ullage case jett
1968 Dec 21	1302:25	S-IVB main engine cutoff
1968 Dec 21	1302:35	Earth orbit insertion,	179 x 190 km x 32.6 deg
			184 x 185 x 32.51 (MPR)
1968 Dec 21	1541:38	S-IVB TLI burn
1968 Dec 21	1546:55	S-IVB main engine cutoff
			218 x 515868 x 30.64 (V)
			218 x 505823 x 30.64 (C3)
1968 Dec 21	1547:05	Translunar injection	214 x 544356 x 30.71
1968 Dec 21	1611:59	S-IVB-503 separation	141 x 538222 x 30.71
			218 x 520371 x
1968 Dec 21	1746:56	LH2 venting 2.1m/s
	1758:56	LOX venting, dV 20.4m/s
	1803:56	Venting complete
	1816:55	Aux motor dep. burn 19.4m/s
	1829:34	Aux motor depletion, solar orbit
1968 Dec 24	1045?	Pass 1780 km above Apollo
1968 Dec 24	1049:55	Lunar flyby 1263 km over 19.2N 88.0E	1263 x Inf x 44.56
1968 Dec 27		0.7Mkm
1968 Dec 31		1.0Mkm
1969 Jan 7		1.75Mkm
		Solar orbit 340.8d 137.95x147.74Mkm x 23.47 deg