Spy Satellite Launch Tests Final Delta 4 Configuration

NROL-25 launched aboard a ULA Delta 4 Medium+ (5,2) rocket on April 3 (Credits: US Air Force/Staff Sgt. Andrew Satran).

On April 3, US spy satellite NROL-25 launched from California aboard a Medium+ (5,2) configuration Delta 4 rocket. The launch is presumed to be successful, although due to the secrecy of its mission, live feed of the launch was terminated 3.5 minutes after liftoff. The launch marks the 19th Delta 4 launch but the first in this configuration.

“As the first-ever Medium+ (5,2) mission from either Cape Canaveral Air Force Station or Vandenberg Air Force Base, this launch represents a significant milestone in Delta 4 operations for the nation,” said Lt. Col. Brady Hauboldt, the 4th Space Launch Squadron commander and the Air Force launch director. “It provides final flight verification for all five variants of the Delta 4 rocket and marks the capability of delivering payloads of all sizes and weights to orbit.”

The Delta 4 rocket family (Credits: ULA).

The Delta 4 is a product of United Launch Alliance (ULA) and comprises a family of medium to heavy lift launch vehicles. By mixing-and-matching various stages and nose cones, five different versions of the Delta 4 can be made available to suit specific launch requirements. All but one of these configurations has flown in space since the 2002 debut of the rocket family. With the launch of NROL-25, this final configuration, the Delta 4 Medium+ (5,2), is now flight proven.

The Delta 4 Medium+ (5,2) is a 66 m tall launcher with a hydrogen fueled first stage, two solid propellant side mounted boosters, a cryogenic upper stage, and a 5 m wide nose shroud. Its (5,2) designation derives from use of a 5 m shroud which can be swapped for a 4 m version in smaller configurations, and use of 2 boosters from a choice of 0, 2, or 4.

The US National Reconnaissance Office (NRO), responsible for the NROL-25, is perfecting efforts to sustain series of rapid satellite launches. In 2011, NRO launched six spacecraft in seven months. In 2012, they aim to launch four satellites within five months.

Watch the launch below: