June 29th 2012 - 13:22 UTC

The payload faring has jettisoned on schedule, Due to the nature of the payload no further updates of the mission will be available.

June 29th 2012 - 13:21 UTC

The main engine has now shut down and the entire first stage has separated from the second stage, which has now ignited for it's burn.

June 29th 2012 - 13:20 UTC

The main common booster core is now at full power.

June 29th 2012 - 13:19 UTC

The common booster cores either side of the first stage have shut down and separated.

June 29th 2012 - 13:16 UTC

Passing mach 1 as the maximum dynamic pressure is on the vehicle.

June 29th 2012 - 13:15 UTC

Lift off of NROL-15 on a Delta IV Heavy!

June 29th 2012 - 13:14 UTC

T-1 minute and counting.

June 29th 2012 - 13:11 UTC

Vehicle has been transferred to internal power.

June 29th 2012 - 13:11 UTC

Clocks have begun ticking down from T-4 minutes!

June 29th 2012 - 13:08 UTC

Launch controllers are polling for a fourth time, they are 'GO' for launch.

June 29th 2012 - 12:53 UTC

A new T-0 of 13:15 UTC has been announced.

June 29th 2012 - 12:40 UTC

Engineers are still testing and troubleshooting the valve that failed to close.

June 29th 2012 - 12:18 UTC

The launch team note back pressure was on the valve which stopped it from closing, they are investigating why and if they can fix it for today.

June 29th 2012 - 12:09 UTC

The valve that failed to close on the third launch attempt was in one of the common booster cores. The valve that caused the second countdown hold was in the upper stage.

June 29th 2012 - 12:01 UTC

It is unsure which valve failed to close.

June 29th 2012 - 11:56 UTC

Clocks were held at 3 minutes and 9 seconds. The team are safing the vehicle, no information on a fourth attempt has been announced yet.

June 29th 2012 - 11:56 UTC

A hold has been occurred, the fill/drain valve did not close.

June 29th 2012 - 11:52 UTC

A 'GO' has been given to proceed with the count.

June 29th 2012 - 11:52 UTC

Launch controllers are polling for a third time today.

June 29th 2012 - 11:38 UTC

A new T-0 of 11:59 UTC has been announced, Polling will occur at 11:52 UTC with the countdown clock resuming at 11:55 UTC.

June 29th 2012 - 11:37 UTC

There was a conflict between two computer scripts which caused the valve to open again when it should have been closed. A work around will be to manually secure topping of the fuel tanks and the team are confident in proceeding with a launch attempt today.

June 29th 2012 - 11:30 UTC

Flight controllers have manually cycled the fill/drain value and it operated as expected so the team are working on why they were told it hadn't closed. The team are working on a new T-0 as soon as they are sure the issue is cleared.

June 29th 2012 - 11:20 UTC

A new T-0 of no earlier than 11:40 UTC has been announced.

June 29th 2012 - 11:10 UTC

This second hold was called due to a fill/drain valve that did not close on the upper stage. Engineers are currently assessing the situation.

June 29th 2012 - 10:47 UTC

A hold has been called at 03:17 seconds, The hold was due to an unplanned script abort.

June 29th 2012 - 10:46 UTC

Launch controllers have polled to come out of the count. Launch is now at T-4 minutes and counting, everything is 'GO'.

June 29th 2012 - 10:29 UTC

A new T-0 of 10:50 UTC has been announced.

June 29th 2012 - 10:28 UTC

The hold was caused by a violation of a red line limit during transfer of power to internal battery power. They have confirmed the value is correct and have disabled the monitoring of that particular parameter.

June 29th 2012 - 10:18 UTC

Launch controllers are working on a recycle, They think a new T-0 will be beyond 10:45 UTC.

June 29th 2012 - 10:10 UTC

The clock has stopped at 03:42 and we are NO GO at the moment.

June 29th 2012 - 10:07 UTC

Launch controllers are 'GO' for launch after conducting their poll. The launch countdown is currently in a planned hold at T- 4 minutes.

June 29th 2012 - 07:55 UTC

The three common booster cores that make up the first stage and two boosters have been fully fuelled and the upper stage is in the process of finishing fuelling. Weather has improved to 90% chance of a 'GO' for this mornings launch attempt. Liftoff is on schedule for 10:13 UTC, 06:13 Local time.

June 29th 2012 - 01:25 UTC

The Mobile Service Tower was successfully backed away from the Delta IV Heavy rocket this evening as darkness arrived. Launch is on track for tomorrow at 10:13 UTC, Weather odds have improved with the latest giving a 70% 'GO' for launch.

June 26th 2012 - 17:55 UTC

ULA have delayed the launch 24 hours due to the weather forecast for Tropical Storm Debby. The launch will now occur on Friday June 29th at 10:13 UTC, 06:13 Local time from Space Launch Complex 37 at Cape Canaveral in Florida. The protective Mobile Service Tower will be retracted from the rocket on Thursday evening.

June 26th 2012 - 14:00 UTC

A launch time of the largest rocket in the Delta IV fleet has been set at 10:16 UTC, 06:16 Local time on Thursday 28th. Weather, mainly thick cloud, from Tropical Storm Debby has set chances for launch at just 20%.

June 13th 2012 - 17:00 UTC

Due to the nature of the NROL-15 payload, Specific launch times and events will not be released until very close to launch.