Delta 4-Heavy boosts NRO spysat into space

CBS News

A United Launch Alliance Delta 4 "Heavy," the most powerful rocket in the U.S. inventory, thundered away from Vandenberg Air Force Base, Calif., Wednesday on a classified mission to boost a National Reconnaissance Office spy satellite into orbit.

Made up of three "common core" hydrogen-fueled boosters and a powerful upper stage, the 235-foot-tall Delta 4's trio of RS-68 first-stage engines roared to life at 2:03 p.m. EDT (GMT-4), instantly pushing the rocket away from Space Launch Complex 6 with nearly 2 million pounds of thrust.

A United Launch Alliance Delta 4-Heavy blasts off from Space Launch Complex 6 at Vandenberg Air Force Base, Calif., to boost a classified National Reconnaissance Office satellite into orbit. (Photo: Pat Corkery/United Launch Alliance)
The launching was held up 10 minutes by undisclosed technical snags, but engineers were able to resolve the problems and the final moments of the countdown went off without a hitch.

The 23-story-tall rocket initially climbed straight up through a clear sky and then arced away to the south toward an orbit tilted nearly 90 degrees to the equator. While the nature of the NRO satellite payload was not known, such orbits allow optical and radar reconnaissance spacecraft to observe the entire planet as it rotates below.

With the retirement of NASA's space shuttle, the Delta 4-Heavy is the most powerful rocket launched by the United States, with each Aerojet Rocketdyne first-stage engine generating some 656,000 pounds of push at liftoff.

"There's nothing bigger that the United States launches, period, in any way, shape or form, and that is absolutely amazing," Lt. Col. Jim Bodnar, commander of the 4th Space Launch Squadron at Vandenberg, told Spaceflight Now.

In the six previous flights of a Delta 4-Heavy, excess hydrogen gas escaping from the engines just before launch could ignite at main engine start, creating an alarming-looking fireball at the base of the rocket, in some cases burning away insulation during the initial moments of ascent.

This time around, ULA engineers decided to stagger the start sequence, igniting the right-side booster two seconds ahead the center and left-side engines. The idea was to burn off the excess hydrogen before all three engines were throttled up to minimize the resulting fireball.

The procedure appeared to work, and while discoloration could be seen on the first stage cores, there was noticebly less fire at the moment of liftoff and just after, compared to earlier Delta 4-Heavy launchings.

The climb out appeared normal as well, and the left and right common booster cores separated and fell away about four minutes and 15 seconds after liffoff. The central CBC followed suit just over one minute later.

At that point, the spent first-stage booster core fell away and a few seconds later, the Delta's Aerojet Rocketdyne RL10B-2 second-stage engine ignited to continue the push to space. A few moments after that, the protective payload fairing was jettisoned, exposing the satellite payload to space.

As usual with such blacked-out missions, United Launch Alliance provided commentary through the first six minutes of flight, but no information was provided after that.

"This is Delta mission control at T-plus six minutes and 30 seconds into today's mission," said ULA's launch commentator. "You've just seen the successful liftoff of the NROL-65 mission for the National Reconnaissance Office. Liftoff occurred at 11:03 a.m. Pacific Time. ... At the request of our customer, we're going to be concluding our live coverage."

This was the seventh Heavy version of the Delta 4 to fly, the fifth launched from Vandenberg, and the 24th rocket in the Delta 4 family since its debut in 2002.