Webcast has begun. just some musics:
The big vent that Kyle mentioned:
T-18 minutes.
Here are some statistics on today's flight, from spaceflightnow.com:
33rd launch of a Falcon 9 rocket since 2010
38th launch of Falcon rocket family since 2006
1st launch of Falcon 9 Vehicle No. 32
30th Falcon 9 launch from Cape Canaveral
98th flight from launch pad 39A
4th Falcon 9 launch from pad 39A
13th launch of the upgraded Falcon 9
1st SpaceX launch for NRO
19th Falcon 9 day launch
5th Falcon 9 launch of 2017
7th launch from Cape Canaveral in 2017
T-15 minutes.
Webcast started!
NROL-76 on internal power! Terminal count has started.
The strongback, which supplies electricity and propellant to the Falcon 9, will be retracted 1.5 degrees away from the rocket at about T-3 minutes, 30 seconds. The two clamps below the payload fairing will be moved about a minute beforehand.
While it may look like the strongback has not moved at all, it will be "thrown back" at T0 similar to the Antares launches.
LZ-1
The engine chilldown sequence has started for the nine Merlin 1D+ engines.
All systems GO!
Stage 1 fuel "closed out". RP-1 topping complete.
Vehicle "pressing for strongback" retract sequence.
Strongback retract has started.
T-3 minutes. Strongback is now at the T0 position. Standing by for Falcon 9 to go on internal power.
LOX loading complete on Stage 1.
HOLD at T-52s.
Sensor issue on 1st stage. Launch scrubbed! 2nd launch attempt tomorrow.
NROL-76 will head to LEO.