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Mission
The Delta II is an expendable launch, medium-lift vehicle used to launch
Navstar Global Positioning System (GPS) satellites into orbit, providing
navigational data to military users. Additionally, the Delta II launches
civil and commercial payloads into low-earth, polar, geo-transfer and
geosynchronous orbits.
Features
The Delta II stands a total height of 125.9 feet (37.8 meters). The
payload fairing -- the shroud covering the third stage and the satellite
-- is 9.5 ft wide to accommodate the GPS satellite. A 10-foot (3.3 meters)
wide fairing also is available for larger payloads. Six of the nine solid-rocket
motors that ring the first stage separate after one minute of flight,
and the remaining three ignite, then separate, after burn-out one minute
later.
 Background
The Delta launch vehicle family began in 1959 when NASA's Goddard Space
Flight Center awarded a contract to Douglas Aircraft Company (now Boeing)
to produce and integrate 12 space-launch vehicles. The Delta used components
from the U.S. Air Force's Thor intermediate-range ballistic missile as
its first stage and the U.S. Navy's Vanguard launch-vehicle program as
its second. The first Delta was launched from Cape Canaveral Air Force
Station on May 13, 1960 and had the ability to deliver a 100-pound spacecraft
into geostationary transfer orbit.
In January 1987 the Air Force awarded a contract to McDonnell Douglas,
now Boeing, for construction of 18 Delta IIs to launch Navstar GPS satellites,
originally programmed for launch on the space shuttle. Since then, the
order expanded to accommodate 28 GPS satellite-dedicated launch vehicles.
The first Delta II was successfully launched on Feb. 14, 1989, at Cape
Canaveral. There are two primary versions of the Delta II (6925 and 7925).
The Delta 6925, the first version, carried the initial nine GPS satellites
into orbit.
The Delta program has more than 245 successful domestic and foreign
military and commercial launches. The Delta accomplished many firsts
over the years. These include the first international satellite, Telstar
I, in 1962; the first geosynchronous-orbit satellite, Syncorn II, in
1963; and the first commercial communications satellite, COMSAT I, in
1965.
The Delta II is launched primarily from Cape Canaveral AFS, Fla., but
is also launched from Vandenberg Air Force Base, Calif. Members of Air
Force Space Command's 45th Space Wing, with headquarters at Patrick AFB,
Fla., and 30th Space Wing at Vandenberg are responsible for the Delta
II's military launch missions.
General Characteristics
Primary Function: Space lift vehicle
Builder: Boeing Company, Expendable Launch Systems
Power Plant, first stage: one Rocketdyne RS-27 and two LR-101-NA-11
vernier engines; both use refined kerosene and liquid oxygen as
its propellants; thrust (sea level), 200,000 pounds.
Power Plant, second stage: restartable Aerojet AJ10-110K
motor; uses nitrogen tetroxide and Aerozine 50 propellants; thrust,
9,750
pounds.
Payload assist module: If used, Star-48B Solid-fuel Rocket,
14,920 pounds. Nine Alliant Techsystems strap-on graphite-epoxy
motors surround
the first
stage for augmented lift-off; thrust 100,270 pounds.
Thrust (at liftoff): 699,250 pounds
Launch Sites: Space Launch Complex 17, Cape Canaveral AFS,
Fla.; Space Launch Complex 2, Vandenberg AFB, Calif.
Height: 125 feet, 9 inches (38.32 meters)
Diameter: Fairing -- 9.5 feet (2.87 meters), core -- 8 feet
(2.4 meters)
Weight: 511,190 pounds (231,870 kilograms)
Lift Capability: The Delta II can carry payloads into
near-earth orbits (approximately 100 nautical miles 160
kilometers in space).
It can lift up
to 11,100 pounds (4,995 kilograms) into a 28-degree circular
near-earth orbit and up to 8,420 pounds (3,789 kilograms)
into a 90-degree
polar near-earth orbit. The Delta II also can carry up
to 4,010 pounds
(1,804.5 kilograms)
into geo-transfer orbit (approximately 12,000 miles 19,200
kilometers) and
up to
2,000 pounds (909 kilograms) into geosynchronous orbit
(approximately 22,000 miles 35,200 kilometers).
Payloads: The three-stage Delta 7925 has carried
29 GPS Block II satellites into orbit, with another 19
slated
to launch
as needed.
The
National Reconnaissance
Office's GeoLITE payload will also use a Delta 7925.
A two-stage Delta 7920 launched the Advanced Research and
Global Observation
Satellite,
an Air Force
Space Test Program mission.
Guidance System: Delta Redundant Inertial Flight
Control Assembly manufactured by Allied Signal Aerospace
Date Deployed: November 26, 1990 (7920/7925
series)
Unit cost: Not available
Inventory: Active force, 2 (with more on order)
Point of Contact
Air Force Space Command, Public
Affairs Office; 150 Vandenberg St., Suite 1105; Peterson AFB, CO 80914-4500;
DSN 692-3731, or (719) 554-3731.
Above Information Courtesy
of United States Air Force
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