Delta II

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Delta II

A Delta II rocket launches from Cape Canaveral carrying a GPS satellite
Fact sheet
Function	Launch vehicle
Manufacturer	United Launch Alliance (Boeing IDS)
Country of origin	USA
Cost per Launch (1987)	$36.7m (USD)
Size
Height	38.2 - 39 m (125.3 - 127 ft)
Diameter	2.44 m (8 ft)
Mass	151,700 - 231,870 kg (334,300 - 511,180 lb)
Stages	2 or 3
	Capacity
Payload to LEO	2,700 - 6,100 kg (5,960 - 13,440 lb)
Payload to GTO	900 - 2,170 kg (1,980 - 4,790 lb)
Launch History
Status	Active
Launch Sites	Cape Canaveral LC-17 Vandenberg AFB SLC-2W
Total launches	127 Delta 6000: 17 Delta 7000: 107 Delta 7000H: 3
Successes	125 Delta 6000: 17 Delta 7000: 105 Delta 7000H: 3
Failures	1 (Delta 7000)
Partial Failures	1 (Delta 7000)
Maiden flight	Delta 6000: 14 February 1989 Delta 7000: 26 November 1990 Delta 7000H: 8 July 2003
Last flight	Delta 6000: 24 July 1992
Boosters (6000 Series) - Castor 4A
No boosters	3, 4 or 9
Engines	1 Solid
Thrust	478.3 kN (107,530 lbf)
Specific Impulse	266 sec
Burn time	56 seconds
Fuel	Solid
Boosters (7000 Series) - GEM 40
No boosters	3, 4 or 9
Engines	1 Solid
Thrust	492.9 kN (110,800 lbf)
Specific Impulse	474 sec
Burn time	64 seconds
Fuel	solid
Boosters (7000 Heavy) - GEM 46
No boosters	9
Engines	1 solid
Thrust	628.3 kN (141,250 lbf)
Specific Impulse	278 sec
Burn time	75 seconds
Fuel	solid
First Stage - Thor/Delta XLT-C
Engines	1 RS-27C
Thrust	1,054.2 kN (237,000 lbf)
Specific Impulse	302 sec
Burn time	265 seconds
Fuel	Kerosene/LOX
Second Stage - Delta K
Engines	1 AJ-10
Thrust	43.6 kN (9,800 lbf)
Specific Impulse	319 sec
Burn time	431 seconds
Fuel	Dinitrogen tetroxide/Aerozine
Third Stage - PAM-D (optional)
Engines	1 Star 63
Thrust	107.2 kN (24,100 lbf)
Specific Impulse	282 sec
Burn time	120 seconds
Fuel	Solid

Delta II is a space launch system -- designed and built by Boeing's Integrated Defense Systems division -- which has been in service since 1989. Delta II, which is part of the Delta rocket family, includes the retired Delta 6000, the active Delta 7000, and two variants (lite and heavy) of the latter. The Delta II program became the responsibility of United Launch Alliance on December 1, 2006.

Contents 1 History 2 Vehicle description 3 Delta II launches 3.1 Notable payloads 4 Future Applications 5 External links

[edit] History

All United States expendable launch vehicles were to be phased out for the Space Shuttle, but the Challenger accident restarted Delta development. The Delta II, specifically, was designed to accommodate the GPS Block II series of satellites. Delta IIs have successfully launched 125 projects (through February 2007), including several NASA missions to Mars:

• Mars Global Surveyor in 1996
• Mars Pathfinder in 1996
• Mars Climate Orbiter in 1998
• Mars Polar Lander in 1999
• Mars Odyssey in 2001
• Mars Exploration Rovers (MER-A, Spirit and MER-B, Opportunity) in 2003

[edit] Vehicle description

Deltas are expendable launch vehicles (ELVs), which means they are only used once. Each launch vehicle consists of:

• Stage I: Kerosene and liquid-oxygen tanks that feed the Rocketdyne RS-27 main engine for the ascent.
• Solid rocket booster motors: Used to increase thrust during the initial two minutes of flight. The medium-capacity Delta II has nine motors total (six fire on the ground, three in flight); the other models use only three or four.
• Stage II: Fuel and oxidizer tanks feeding a restartable, hypergolic Aerojet engine that fires one or more times to insert the vehicle-spacecraft stack into low Earth orbit. This stage also contains the vehicle's "brains", a combined inertial platform and guidance computer that controls all flight events.
• Stage III: Optional ATK-Thiokol solid rocket motor (some Delta II vehicles are two-stage only, and generally used for Earth-orbit missions) provides the majority of the velocity change needed to leave Earth orbit and inject the spacecraft on a trajectory to Mars; connected to the spacecraft until done firing, then separates. This stage is spin-stabilized and has no active guidance control; it depends on the second stage for proper orientation prior to Stage II/III separation.
• Payload fairing: Thin metal or composite payload fairing (aka "nose cone") to protect the spacecraft during the ascent through Earth's atmosphere.

The Delta II family is more technically named by a four-digit system:

• The first digit is either 6 or 7, denoting the 6000- or 7000-series Deltas. 6000-series, last flown in 1992, had an Extra Extended Long Tank first stage with RS-27 main engine, plus Castor IVA solid rocket boosters. The current model 7000-series have an RS-27A engine, with a longer nozzle for higher expansion ratio and better high-altitude performance, and GEM (Graphite-Epoxy Motor) boosters. GEMs are larger, and have a composite casing to reduce mass versus the steel-case Castors.

• The second digit indicates the number of boosters, usually 9. In such cases, six are lit at liftoff, three lit one minute into flight. Vehicles with a 3 or 4, ignite all boosters at liftoff.

• The third digit is 2, denoting a second stage with an Aerojet AJ10 engine. This engine is restartable, for complex missions. Only Deltas prior to the 6000-series used a different engine, the TR-201.

• The last digit denotes the third stage. 0 denotes no third stage, 5 indicates a PAM (Payload Assist Module) stage with Star 48 solid motor, 6 indicates a Star 37 motor.

For example, a Delta 7925 has the later first stage, nine GEM boosters, and a PAM third stage. A Delta 7320 is a two-stage vehicle with three boosters.

• A Delta II-Heavy has the larger GEM-46 boosters, originally designed for the Delta III. These are designated 7xxxH.

Three payload fairings are available. The original aluminum fairing, seen above, is 9.5 feet in diameter. A 10-foot fairing is made of composite, and can be distinguished by its tapering front and rear. A lengthened 10-foot fairing is used for the largest payloads.

[edit] Delta II launches

Main article: Delta II launches

[edit] Notable payloads

• NEAR
• Mars Global Surveyor
• Mars Pathfinder
• Deep Space 1
• Mars Climate Orbiter
• Mars Polar Lander
• 2001 Mars Odyssey
• CONTOUR
• Mars Exploration Rovers: Spirit (MER-A)/Opportunity (MER-B)
• Swift
• Deep Impact
• SIRTF
• MESSENGER
• STEREO
• THEMIS

[edit] Future Applications

The Aerojet-built second-stage engine has been chosen by NASA to be used as the main propulsion engine for the Orion spacecraft that will replace the Space Shuttle after 2010. The engine was chosen due to its restart capabilites along with a switch from the original liquid oxygen/liquid methane (LOX/LCH₄) application to hypergolic fuel and oxidizer similar to that in use on the Shuttle's OMS and RCS systems.

[edit] External links

• Boeing Delta II Page
• Delta I, II und III Site from Gunter Krebs
• History of the Delta Launch Vehicle
• Article about 1997 failed launch and self-destruction (with video)