Overview of the Delta 2 rocket's 7420 vehicle configuration used in Globalstar launches. Photo: Boeing

Boeing will again use a Delta 2 7420-10 to launch four satellites for Globalstar's telecommunications network. This will be the seventh Delta 2 launch for Globalstar, each delivering four satellites into low-Earth orbit. A Delta 2 successfully launched the first eight satellites for the system on February and April 1998, from Cape Canaveral Air Station, Fla., and four additional satellites were added to the Globalstar network on June 10, July 10 and 24 and August 17.

The Globalstar network is a planned constellation of 48 satellites orbiting at 764 nautical miles (1414 km) above the Earth. The Globalstar network will supply worldwide telecommunications service.

Aside from the unique four-solid-rocket-motor configuration of the Delta 2 7420, Boeing engineers designed a satellite dispenser for the four satellites. The satellites are paired and attached to the dispenser in upper and lower tiers. Approximately one hour and seven minutes into flight the upper pair separates from the dispenser followed four minutes later by the lower two satellites.

Boeing manufactures Delta rockets in Huntington Beach, Calif., with final assembly in Pueblo, Colo. The 7420-10 two-stage launch vehicle has four major assemblies: the first stage, including main engine and four strap-on solid propellant rocket motors; interstage; second stage; and 10-foot diameter payload fairing. The Delta 2 is approximately 126 feet tall and eight feet wide.

Manufactured by Rocketdyne, a division of Boeing, the RS-27A main engine operates on liquid oxygen and RP-1 (kerosene). The RS-27A has a sea-level thrust of 200,000 pounds. Each of the four Alliant Techsystems solid strap-on motors has a sea-level thrust of 100,270 pounds. The main engine and the four solid rocket motors deliver a total thrust of 483,000 pounds at liftoff.

An Aerojet AJ10-118K engine powers the second stage and burns Aerozine-50 fuel and nitrogen tetroxide oxidizer. Ignited at altitude, the engine has a vacuum-rated thrust of 9,815 pounds.

File photo gives an aerial view of a Delta 2 rocket launching into space. Photo: USAF

The Boeing family of launch vehicles is derived from the Delta family of rockets built and launched since 1960. In that time more than 270 Deltas have been launched.

Delta 2 rockets can be configured as two- or three-stage vehicles depending on mission requirements. The latest version, the Delta 2 7925 model, can boost 3,965 pounds (1800 kg) to geosynchronous transfer orbit (GTO).

Today, Boeing has a growing list of commercial customers, including Hughes Space and Communications International, Inc., Space Systems/Loral, and Motorola. Delta rocket were used to launch 24 satellites to form the cornerstone of the Globastar system.

To serve its commercial customers, Boeing has agreements with the U.S. Air Force and NASA for the use of two government-owned launch pads at Space Launch Complex 17, Cape Canaveral Air Station, Fla., and one pad at Space Launch Complex 2, Vandenberg Air Force Base, Calif.

Major subcontractors include: Alliant Techsystems, Magna, Utah, graphite epoxy motors for boost assist; Aerojet, Sacramento, Calif., second-stage engine; Thiokol, a subsidiary of Cordant Technologies, Elkton, Md., third-stage solid rocket motor; and AlliedSignal, Teterboro, N.J., Redundant Inertial Flight Control Assembly (RIFCA) provides course and attitude control.