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 2:16:11 a.m. EDT, August, 2nd 2004. The mission was launching atop a Boeing Delta II Heavy, from Kennedy Space Center, CCAFS
| Time EDT | L-(time) | Events |
|---|---|---|
| 11:41 p.m. | L-02:35 | the Delta II rocket's first stage is fueled. Fuel is RP-1, a highly refined kerosene propellant. 10,000 gallons are used |
| 12:00 a.m. | L-02:16 | RP-1 fueling completed after 18 minutes and 41 seconds (total used: 9,949 gallons) |
| 12:12 a.m. | L-02:04 | the T-96 minute weather briefing deems that there is a 30% chance of weather violation due mostly to clouds. Launch is green on all weather constraints however |
| 12:20 a.m. | L-01:56 | poll is ok for cryo tanking. |
| 12:24 a.m. | L-01:52 | anvil clouds and tropical storm "Alex" bring a red on cloud constraints. Another weather check is expected between 12:30 and 12:45 a.m. |
| 12:33 a.m. | L-01:43 | the Delta II first stage is now filled with super-cold liquid oxygen (LOX) |
| 12:49 a.m. | L-01:27 | during cryo loading, ice forms on the outside of the rocket |
| 12:59 a.m. | L-01:17 | NASA Assistant Launch Manager reports that if the anvil clouds are transparent they won't pose a problem but if their are thick, this could become a launch issue |
| 1:00 a.m. | L-01:16 | cryo tanking is completed (it lasted 27 minutes). The Delta II rocket is now fueled to 95%. The remaining will be topped shortly before launch |
| 1:13 a.m. | L-01:03 | preparing for engine steering ("engine slews") checks. Second stage is checked first, then first stage |
| 1:19 a.m. | L-:57 | second stage engine steering checks completed |
| 1:23 a.m. | L-:53 | first stage engine steering checks completed |
| 1:26 a.m. | L-:50 | T-20 minute hold. This is a built-in hold. Launch is on schedule. The hold is used to review various questions The craft and the rocket are ready. Launch is still red on anvil clouds. As the liquid oxygen valve being cycled on and off, periodical "puffing" steam can be seen at the rocket. NASA Launch Manager completes his poll on whether to proceed again with the count. The Boeing Launch Director is conducting his own poll. All team members are giving a go for continuing the countdown |
| 1:46 a.m. | L-:30 | the T-20 hold is ending. The countdown is resuming |
| 1:50 a.m. | L-:26 | T-15 minutes and counting. |
| 1:56 a.m. | L-:20 | the weather aircraft is reporting that the anvil clouds which the team hoped would be transparent appear to be thick clouds. This is a weather constraint! All other weather, like the craft and the vehicle, are remaining green. countdown continues but weather is monitored closely |
| 1:57 a.m. | L-:19 | beacon is on internal power. |
| 2:02 a.m. | L-:14 | a new built-in hold occurs. It lasts 10 minutes the Launch Weather Officer reports that as of now, launch is no go for launch due to weather. Further weather assessment continues during the hold |
| 2:09 a.m. | L-:07 launch cancelled! | decision is taken to cancel the launch due to weather constraints. The team decides a new launch 24 hours later, on Tuesday, August 3, at 2:15:56 a.m |
| the mission has a launch window available until August, 14th. Weather predictions remain similar for the next launch. If tropical storm "Alex" moves farther away, the forecast will likely improve |
