Delta II 7320

Delta II 7320 is a member of the Delta II series of expendable launch vehicles developed in the late 1980s and used extensively by NASA, the United States Air Force, and commercial operators. The 7320 configuration combined a two-stage core with strap-on solid rocket motors and a payload fairing optimized for medium-class payloads to low Earth orbit and geosynchronous transfer orbit missions. It became a workhorse for scientific, navigation, and commercial satellites, participating in programs overseen by institutions such as Jet Propulsion Laboratory, Goddard Space Flight Center, and the National Reconnaissance Office.

Design and Development

The 7320 configuration evolved from earlier designs by Douglas Aircraft Company and later development under McDonnell Douglas and The Boeing Company, reflecting design lineage traced to the Thor missile and the Delta IV conceptual family. Engineering teams at Huntington Beach, Cape Canaveral Space Force Station, and Vandenberg Space Force Base refined the vehicle to meet mission requirements from agencies including NASA, NOAA, and the United States Air Force. Flight-proven heritage from missions involving spacecraft built by Lockheed Martin, Ball Aerospace, and Northrop Grumman informed choices on structures, avionics, and propulsion. Collaborative programs with contractors such as Aerojet Rocketdyne and suppliers in the Aerospace Corporation network shaped stage separation and payload fairing integration used on 7320 flights.

Technical Specifications

The 7320 used a two-stage architecture with a first stage powered by the RS-27A engine produced by Aerojet Rocketdyne and a second stage employing a restartable AJ10 engine from Pratt & Whitney. The "7320" designation encodes specific features: seven strap-on solid rocket motors derived from designs by Thiokol (now Northrop Grumman Innovation Systems), a 3-meter diameter payload fairing shared with programs at Jet Propulsion Laboratory, two stages, and a zero indicating absence of a third liquid stage. Structural elements were fabricated by teams at United Launch Alliance facilities and tested at Stennis Space Center and Marshall Space Flight Center. Avionics incorporated guidance units compatible with Inertial Navigation Systems developed for platforms used in collaborations with Raytheon and mission integration practices followed standards from National Institute of Standards and Technology-influenced contractors.

Launch History

Delta II 7320 flights occurred from launch complexes at Cape Canaveral Space Force Station and Vandenberg Space Force Base, supporting launch campaigns coordinated by Kennedy Space Center and mission control centers at Jet Propulsion Laboratory and Goddard Space Flight Center. Notable launch events paralleled major programs such as the Global Positioning System modernization and science missions associated with NASA initiatives. The 7320 participated in launches that tracked milestones comparable to those of the Mars Exploration Program and environmental missions akin to Landsat operations. Launch cadence and flight success records were documented alongside contemporaneous platforms like Atlas II and Delta III.

Payloads and Missions

Payloads flown on 7320-configured vehicles included navigation spacecraft, scientific satellites, and classified payloads manifested through agencies such as the National Reconnaissance Office and National Oceanic and Atmospheric Administration. Scientific missions shared programmatic similarities with instruments developed for Hubble Space Telescope servicing missions and Earth-observing programs executed by NASA and NOAA. Commercial telecommunications satellites built by manufacturers like Thales Alenia Space and Boeing Satellite Systems also flew on Delta II variants, while scientific payloads from institutions such as California Institute of Technology, Massachusetts Institute of Technology, and University of California, Berkeley were integrated for heliophysics and planetary science objectives.

Variants and Modifications

The 7320 was one configuration among multiple Delta II variants, each identified by a four-digit code reflecting strap-on count, second-stage type, and fairing size; related variants included configurations used in missions comparable to those flown by Delta 7920 and Delta 7326 patterns. Modifications over time addressed upgraded avionics, improved solid rocket motor casings developed in cooperation with Orbital Sciences Corporation, and enhanced telemetry suites compliant with standards used by NASA mission operations. Evolution of the Delta II line informed successor projects at United Launch Alliance and contributed to lessons applied in programs like Atlas V and the later Vulcan Centaur development effort.

Category:Delta (rocket family) Category:Expendable space launch systems of the United States