T-(Time-minus) used in the rightmost column is time remaining until launch holds included as L-(Launch-minus) given in the grey-hued column is time remaining until launch holds not included. A poll points to a special procedure used during countdowns. Decisions about countdown and launch are based on a poll process where NASA Launch Manager takes the advice of other members of the launch team. see more at "How a Launch Team is Working"
Mission MESSENGER scheduled launch was at 2:15:56 a.m. EDT, August, 3rd 2004. The mission was launching atop a Boeing Delta II Heavy, from Kennedy Space Center, CCAFS
| Time EDT | L-(time) | Events |
|---|---|---|
| 10:50 p.m. | L-03:25 | we are in a 60 minutes built-in hold just before the terminal phase of the countdown The launch complex is cleared of all personnel |
| 10:58 p.m. | L-03:17 | spacecraft and launch vehicle are green for launch. Weather is still red the poll on whether to proceed with the terminal count is conducted as everyone agrees to procede |
| 11:07 p.m. | L-03:08 | terminal countdown briefing. Weather is still red |
| 11:16 p.m. | L-02:59 | T-150 and counting. Beginning of the terminal countdown (the horn has been sounded at the pad as the warning beacon has been activated) |
| 11:19 p.m. | L-02:56 | helium and nitrogen storage tanks pressurization of the first and second stages begins |
| 11:41 p.m. | L-02:34 | RP-1 fuel loading into first stage begins. Such a "rapid load" is allowing to pour 10,000 gallons of RP-1 fuel (a highly refined kerosene) in the first stage |
| 11:55 p.m. | L-02:20 | the first stage has been filled to 98%. Remaining is filled later |
| 12:13 a.m. | L-02:02 | T-95 weather briefing. Weather is remaining red due to anvil clouds and thick clouds. Earlier thunderstorms are dissipating however and there is a chance that the remnant cloud cover continue to thin |
| 12:19 a.m. | L-01:56 | polls for the cryogenic tanking. Weather is the sole parameter at red. Poll is go |
| 12:32 a.m. | L-01:43 | cryogenic tanking begins. Super-cold liquid oxygen (LOX) is poured into Delta II first stage. This will take about 40 mn to complete. During the procedure gaseous oxygen (GOX) is released and is seen venting from the rocket |
| 1:08 a.m. | L-01:07 | LOX loading complete |
| 1:17 a.m. | L-:58 | engine steering checks ("slews"). The second stage is checked first then first stage |
| 1:23 a.m. | L-:52 | engine steering checks completed. |
| 1:25 a.m. | L-:50 | the T-20 minute built in hold begins. It lasts 20 minutes |
| 1:27 a.m. | L-:48 | clouds are thin and transparent, and anvil clouds are not a concern at this time. They have to be monitored however |
| 1:38 a.m. | L-:37 | final launch poll. All constraints are green. Upper level winds are green. |
| 1:46 a.m. | L-:29 | T-20 minutes and counting. The hold ends |
| 1:54 a.m. | L-:21 | T-12 minutes and counting. Range safety command checks completed |
| 1:56 a.m. | L-:19 | T-10 minutes and counting. Upper level wind continues to be acceptable. |
| 1:57 a.m. | L-:18 | LOX tank is cycled on and off causing smoke to puff out of the rocket. |
| 2:00 a.m. | L-:15 | LOX is topped to 100% and maintained between 915% and 100% until launch. Launch Weather Officer reports weather is go. |
| 2:01 a.m. | L-:14 | T-4 minutes. A new built-in hold. It lasts 10 minutes |
| 2:09 a.m. | L-:06 | all polls for launch are go. All constraints are green Should any alarm occur once the countdown taken back a hold will be called. There are no allowable alarms after T-60 seconds. |
| 2:10 a.m. | L-:05 | spacecraft is configured for launch and passes on internal power. |
| 2:11 a.m. | L-:04 | T-4 minutes. End of the 10-minute hold. Spacecraft is green. |
| 2:12 a.m. | L-:03 | T-3 minutes and counting. |
| 2:14 a.m. | L-:00:60 | no more alarms allowable |
| 2:15 a.m. | L-:00:30 | T-30 seconds. LOX fill and drain valve is closed |
| 2:15 a.m. | L-:00:10 | T-10 seconds. 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 ... |
| 2:15 a.m. | liftoff | ... and liftoff! Mission MESSENGER is leaving for Mercury! official launch time is 2:15:56.537 a.m. |
| into the flight | ||
| 2:18 a.m. | :03 | three solid boosters have been jettisoned. Delta II is already 215 NM (nautical miles) away. |
| 2:20 a.m. | :05 | main engine cutoff; second stages has separated and its engine has ignited. |
| 2:21 a.m. | :06 | launcher is 77.5 NM in altitude |
| 2:24 a.m. | :09 | second stage cutoff. A 37-minute coast begins |
| 2:35 a.m. | :20 | the Ascension Island Tracking Station is acquiring MESSENGER signal. |
| 2:39 a.m. | :24 | second stage data normal |
| 2:42 a.m. | :27 | loss of signal from Ascension Island as the Delta II goes over the horizon. Next telemetry station is in about 19.5 minutes at the OTTR (U.S. Air Force Deployable Telemetry shipboard station) |
| 2:51 a.m. | :36 | MESSENGER is passing over the Eastern tip of Africa. |
| 3:01 a.m. | :46 | the Indian Ocean OTTR station acquires the craft |
| 3:02 a.m. | :47 | second stage's second burn occurs. It lasts just under 3 minutes |
| 3:05 a.m. | :50 | second stage shutdown! Spin-up. The craft is in orbit |
| 3:06 a.m. | :51 | third stage ignition. The craft is to be put on its trajectory. The mission is now tracked by the PERL Station USAF Deployable telemetry station at Exmouth, Australia. |
| 3:07 a.m. | :52 | end of third stage burnout |
| 3:11 a.m. | :56 | it's now the USN Station in Dongara, Australia which is tracking the mission |
| 3:12 a.m. | :57 | spacecraft separation achieved! Mission MESSENGER is on its way to Mercury! |
| alternate timing for a interplanetary launch may unfold like solid rocket motors are jettisoned at about launch plus 106 seconds. First, solids 1 and 2 separate from the rocket, followed 1.5 seconds later by solids 3, 4 and 5. Fairing separate at about launch plus 4 minutes, 45 seconds freeing the mission and its Centaur upper stage. The Centaur upper stage provide the final kick through two scheduled burns as parking at 17,500 miles per hour occurs at about launch plus 10 minutes, 45 seconds and the Centaur upper stage temporarily stoping firing and the mission coasting during 30 minute, or a 'parking orbit.' The second, 9-minute long burn occurs at about launch plus 41 minutes, 33 seconds placing the mission on its interplanetery journey as the craft eventually separate from the Centaur at about launch plus 56 minutes |
