Delta II 7925H-9.5

Delta II 7925H-9.5

The Delta II 7925H-9.5 is an American expendable orbital launch vehicle operated by Boeing Launch Services and later United Launch Alliance (ULA), developed from the long-running Delta II family produced by McDonnell Douglas and its successors. A workhorse of the medium-lift class, it represents one of the most refined configurations of a rocket lineage that traces its origins to the early 1960s and became one of the most reliable orbital launch systems in spaceflight history.

Configuration and Design

The 7925H-9.5 designation encodes the vehicle's specific configuration within the Delta II family. The "7" denotes the Delta II series, "9" indicates nine strap-on solid rocket boosters, "2" refers to a Rocketdyne RS-27A main engine on the first stage, "5" identifies the second-stage engine, and "H" denotes the use of the larger, higher-thrust graphite-epoxy motors (GEMs) rather than the standard casings. The "9.5" refers to the 9.5-foot (2.9 m) payload fairing, the largest available for the Delta II family, offering additional volume for larger spacecraft. The core vehicle stands 40 meters tall with a base diameter of 2.44 meters. The vehicle is capable of delivering up to 5,959 kg to low Earth orbit and 2,190 kg to geostationary transfer orbit, placing it firmly in the medium-lift category.

Flight History

In the tracking dataset maintained by this site, the Delta II 7925H-9.5 — encompassing the broader Delta II family across its active period — recorded 155 flights between 1989 and 2018, of which 153 were successful and 2 resulted in failure or partial failure. This yields a mission success rate exceeding 98%, a figure that underscores the vehicle's reputation for reliability across nearly three decades of operation.

The Delta II family launched from Cape Canaveral Space Launch Complex 17 in Florida and Vandenberg Space Force Base in California, with the latter serving primarily for sun-synchronous and polar orbit missions. The rocket's primary customers across its operational life included the United States Air Force and United Launch Alliance, though it also flew numerous missions for NASA and commercial operators.

Notable Missions

Among the most significant payloads carried by the Delta II in its later years were a series of high-profile NASA Earth science and science missions. These included the GRAIL-A (Ebb) and GRAIL-B (Flow) lunar gravity mapping spacecraft, the NPP and JPSS-1 polar weather satellites, the OCO-2 carbon-observing spacecraft, the SMAP soil moisture mapper, and the ICESat-2 ice-sheet altimetry satellite. These missions reflect the vehicle's strong association with NASA's Earth Observing System program and its trusted role in delivering precision scientific instruments to demanding orbits.

Legacy

The final Delta II flight took place in 2018, closing out one of the longest and most storied careers of any American launch vehicle. Its combination of high reliability, adaptable configurations, and consistent performance across government and scientific missions earned it an enduring place in the history of orbital spaceflight. The 7925H-9.5 configuration, with its enlarged fairing and enhanced solid boosters, represented the vehicle at the peak of its capability.