Surveyor M-1

  1964-082A

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AC-4 was launched at 1425 on 1964 Dec 11 on the first attempt at a two-burn Centaur mission. The two-burn profile was needed for the parking orbit technique in which Surveyor probes would first be placed in Earth orbit, then injected into a precise lunar trajectory. Centaur AC-4 carried a simple model, M-1 of the Surveyor which reproduced the real probe's mass distribution, but not its detailed shape.

The first Centaur burn went well and orbit insertion was achieved at 1434 UT. The second burn, scheduled for 50s, should have inserted AC-4 into a 160 x 8000 km orbit, but when the engines ignited at 1459 on Dec 11, the stage was tumbling and rolling, and propellant didn't reach the pumps. AC-4 remained in a 87.8 min, 165 x 178 km x 30.7 deg orbit and reentered at around 0530 on Dec 12 over the South Pacific. 

According to a NASA report the AC-4 flight showed that transfer of kinetic energy within the stage to the propellants at engine cutoff caused liquid instead of gaseous hydrogen to be vented. The liquid contacting the forward bulkhead caused the vehicle to tumble. Fixes to the venting and propellant management systems, including higher thrust ullage motors and slosh baffles, were successfully tested on AC-8.

Surveyor M-1
Date	Time	Event	Orbit
1964 Dec 11	1425:02	Launch by AC-4	CC LC36A
	1427:32	T+2:30 Atlas BECO 56 km Vi 2.848 km/s	-5979 x 108
	1427:35	T+2:33 Booster jettison
		Azimuth 102.5 deg
	1428:22	T+3:20 panels sep 98 km Vi 3.307 km/s	-5782 x 134
	1428:26	T+3:24 Fairing sep, 109 km 3.473 km/s	-5713 x 140 x 30.4?
	1428:46	T+3:44 Atlas SECO 116.9 km 3.636 km/s
	1428:48	T+3:46 Atlas sep 118.6 km 3.637 km/s
	1428:56	T+3:54 Centaur MES-1 338s 124.1 km 3.622 km/s	-5625 x 144 x 30.4
	1434:35	T+9:33 Centaur MECO-1 168.5km 7.810km/s	163 x 176 x
	1439	T+14:00 Centaur venting
	1439	Centaur starts to tumble
	1442	T+17:06 Fairing impact at 25 50N 70 33W
	1459:12	T+34:10 Centaur MES-2	87.8 165 x 178 x 30.7
	2100?	end of tx
1964 Dec 12	0530?	Reentered over Pacific after 10 orbits