Photos: Delta 2 rocket blasts off with SMAP satellite

This is the launch timeline to be followed by the Atlas 5 rocket’s ascent into orbit from Cape Canaveral with the SBIRS GEO Flight 4 satellite for U.S. military infrared reconnaissance.

The United Launch Alliance Atlas 5 rocket, standing 194 feet tall and and weighing 950,000 pounds, unleashes 1.5 million pounds of thrust from its main engine and two side-mounted boosters at 8:37 a.m. EDT today to launch the National Reconnaissance Office’s NROL-61 satellite from Cape Canaveral.

The most powerful Atlas rocket to ever fly from the West Coast is poised for launch Thursday to deliver a secret payload into orbit while debuting a new upper stage engine.