United Launch Alliance's (ULA) second-to-last flight of its Delta IV Heavy rocket lit the Florida Space Coast sky on the NROL-68 mission to haul a classified payload for the U.S. government's spy satellite agency, the National Reconnaissance Office (NRO).

The 235-foot-tall (71.6-meter) Delta 4-Heavy climbed away from Cape Canaveral Space Force Station's (CCSFS) Space Launch Complex 37B (SLC-37B) Thursday at 5:18 a.m. EDT (0918 UTC). NROL-68 marks the 15th flight of Delta IV Heavy, which debuted in 2004, and its eleventh mission for NRO. ULA's Vulcan Centaur rocket will replace its Delta rocket fleet.

We don't know anything about the satellite on NROL-68. That comes as no surprise considering that it is an NRO payload; the organization manages the fleet of American spy satellites, whose capabilities and operations are frequently kept under wraps.

The largest member of the Delta IV family and one of the most powerful rockets in the world is the Delta IV Heavy from United Launch Alliance. A common booster core (CBC), a cryogenic upper stage, and a 5-meter-diameter payload fairing (PLF) make up the Delta IV Heavy configuration.

In addition to the first-stage CBC, the Delta IV Heavy uses two extra CBCs as liquid rocket boosters. It has a capacity to lift 13,810 kg (30,440 lbs) for geostationary transfer orbit and 28,370 kg (62,540 lbs) for low Earth orbit. It is a liquid-fueled rocket with a single main booster, two strap-on boosters, and an upper stage.

Related Links
National Reconnaissance Office
Rocket Science News at Space-Travel.Com