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.

Mission leaders Tuesday gave approval for rollout of the United Launch Alliance Atlas 5 rocket on Wednesday morning, leading to liftoff Thursday night of the Magnetospheric Multiscale science project for NASA.

These narrated videos show the pre-launch preparations that readied the United Launch Alliance Atlas 5 rocket and the Orbital ATK Cygnus commercial cargo-delivery spacecraft for flight and rolling to Complex 41 for liftoff to the International Space Station.