Share |

Atlas V Countdown Timeline

T-	L-	Event
Events	12:00	Verfiy Countdown Clock is in proper Configuration
specified at		Countdown Begins
L-12:00 and		MLP Clear of non essential personnel
L-8:30 are		Launch Pad Environmental Control System Preps
performed		Nitrogen Purge
during L-2-		Weather Briefing
Day		Search Light Power Up
operations,		SLC41 warning lights on
but can take	08:30	MLP to Launch Pad
place until		MLP Hard Down and Securing
that point to		Atlas System Start in preparation for Tanking
meet the T-0		Instrument Checks
requirement.		Lox System Preparations
		Gas Detection System Preparations
		Internal Battery Checks
		LH2 System Preparations
	10:00	Countdown Clock Initialization
	08:00	NEMO On Station
	07:45	ULA On Station
	07:30	Launch Team on Station
	07:20	Set Roadblocks
	07:15	Launch Vehicle Powerup
	07:00	5SLS on Station
	06:50	Communication Checks
	05:40	Weather Briefing
	05:15	Communication Checks
	05:15	C-Band Communication Checks
	05:05	Weather Balloon Release
	04:35	S-Band Communication Checks
	04:15	L-4HR Commanding
	04:15	Polls
	03:50	Initiation of Nitrogen Flow
	03:49	Set Spacecraft Clock
	03:15	SLC Clear of all Personnel
02:00	02:55	Launch Conducter Briefing on Vehicle Conditions
HOLDING		GO/No GO for Tanking Poll
30min Hold		Pre-Test Tanking Briefing
02:00	02:25	Centaur LOX Tank Chilldown
COUNTING	02:25	Atlas LOX Vault & MLP Chilldown
	02:25	Centaur Helium Storage Bottle Pressurization
	02:25	Atlas Pressure Vessels Charge
	02:25	Atlas V RP-1 Fuel Tank Press
01:55	02:20	Safe Arm Device Cycle Test
01:50	02:15	Centaur LOX Transfer Line Chilldown
01:43	02:08	Centaur LOX Tanking begins
01:40	02:05	Weather Balloon Release
01:33	01:58	Centaur LH2 Tank Press to Chilldown Level
01:30	01:55	Atlas V LOX Tanking begins
01:25	01:50	Centaur LOX at 75%
01:25	01:50	Centaur LH2 Transfer Lines Chilldown
01:10	01:35	Centaur Engine Chilldown
01:02	01:27	Centaur LH2 Loading
00:55	01:20	Flight Control Final Preparations for Hydraulic Press
00:45	01:10	Main Engine Pneumatic System Press to Flight Level
00:40	01:05	Heater Activation
00:40	01:05	FTS Test
00:35	01:00	FGM Activation
00:25	00:50	Load Boost Block
00:20	00:45	Fault Protection Validation
00:17	00:42	Polls for Terminal Countdown
00:16	00:41	Fuel Fill Sequence Initiation
00:15	00:40	History Data Dump
00:15	00:40	Term CT Configuration complete
00:11	00:36	Range Clear for Launch
00:10	00:35	Weather Briefing
00:07	00:32	Range Clear Poll
00:06	00:31	Spacecraft GO/No GO Poll
00:06	00:31	NAM Poll
00:06	00:31	SMD Poll
00:05	00:30	Fuel Fill Sequence Complete
00:05	00:30	Water Deluge System actuation Pressure Adjustment
00:05	00:30	Cenataur LOX at Flight Level
00:05	00:30	Centaur LH2 at Flight Level
00:04	00:14	NLM Poll
HOLDING	00:09	Launch Director Final Poll
	>>>>	SAFE L-9MIN CONFIGURATION FOR EXTENDED HOLDS
Variable	00:07	Spacecraft Status Check
Hold	00:06	Spacecraft on internal Power
Planned:	00:06	LD GO to Launch
25min	00:05	Range Clear Validation
COUNTING	00:04	Hazardous Gas Monitoring Complete
00:04	00:04	Automatic Sequence Begins
00:04	00:04	Atlas LOX Replenish Terminated
00:04	00:04	Atlas LOX Tank Pressurization
00:03	00:03	Atlas Tanks at Flight Pressure
00:02	00:02	Atlas and Centaur switch to internal Power
00:01:55	00:01:55	CMD Sequence
00:01:50	00:01:50	Centaur Topping Sequence complete
00:01:30	00:01:30	Launch Control System Enabled
00:00:16	00:00:16	Launch Verification
00:00:02.7	00:00:02.7	Main Engine Start
+00:00:01.1	+00:00:01.1	Liftoff

Launch Date	August 30, 2012
Launch Time	8:05 - 8:25 GMT
Launch Site	Cape Canaveral Air Force Station
	Space Launch Complex 41
Launch Opportunities	Aug. 23 through Sep. 24

---

Launch Vehicle

Photo: NASA Kennedy

Atlas V 401

>>>Launch Vehicle Information

---

Links

>>>Ascent Information 
>>>Launch Weather Forecast

---

Image: United Launch Alliance

---

---