Atlas II

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Atlas II

Launch of an Atlas II rocket. (NASA)
Fact sheet
Function	Medium expendable Launch vehicle
Manufacturer	Lockheed Martin
Country of origin	USA
Size
Height	47.54 m (156 ft)
Diameter	3.04 m (10 ft)
Mass	204,300 kg (414,000 lb)
Stages	3.5
	Capacity
Payload to LEO	6,580 kg
Payload to GEO	2,810 kg
Launch History
Status	Retired
Launch Sites	LC-36, CCAFS SLC-3 Vandenberg AFB
Total launches	63 10 Atlas II 23 Atlas IIA 20 Atlas IIAS
Successes	63
Maiden flight	Atlas II: 7 December 1991 Atlas IIA: 10 June 1992 Atlas IIAS: 16 December 1993
Last flight	Atlas II: 16 March 1998 Atlas IIA: 5 December 2002 Atlas IIAS 31 August 2004
Notable payloads	SOHO (Atlas IIAS) TDRS (Atlas IIA)
Boosters (Atlas IIAS) - Castor 4A
No boosters	4
Engines	1 Solid
Thrust	478.3 kN (107,530 lbf)
Specific Impulse	266 sec
Burn time	56 seconds
Fuel	Solid
Boosters (all) - MA-5
No boosters	1
Engines	2 RS-58-OBA
Thrust	2,093.3 kN (470,680 lbf)
Specific Impulse	299 sec
Burn time	172 seconds
Fuel	LOX/RP-1
First Stage
Engines	1 RS-58-OSA
Thrust	386 kN (86,844 lbf)
Specific Impulse	316 sec
Burn time	283 seconds
Fuel	RP-1/LOX
Second Stage - Centaur
Engines	2 RL-10A
Thrust	147 kN (41,592 lbf)
Specific Impulse	449 sec
Burn time	392 seconds
Fuel	LH2/LOX
Third Stage - IABS (optional)
Engines	1 R-4D
Thrust	980N (220 lbf)
Specific Impulse	312 sec
Burn time	60 seconds
Fuel	N2O4/MMH

Atlas II was a member of the Atlas family of launch vehicles, which evolved from the successful Atlas missile program of the 1950s. Atlas II was the last Atlas to use a three engine, "stage-and-a-half" design: two of its three engines were jettisoned during ascent, but its fuel tanks and other structural elements were retained. It was designed to launch payloads into low earth orbit, geosynchronous transfer orbit or geosynchronous orbit. Sixty-three launches of the Altas II, IIA and IIAS models were carried out between 1988 and 2004. (The larger Atlas III was used between 2000 and 2005, and the Atlas V is still in use.)

Contents 1 Features 2 Background 3 References 4 External links

[edit] Features

Atlas II provides higher performance than the earlier Atlas I by using engines with greater thrust and longer fuel tanks for both stages. The total thrust capability of the Atlas II of 490,000 pounds force (2,200 kN) enables the booster to lift payloads of 6,100 pounds (2,767 kg) in geosynchronous orbit of 22,000 miles (35,000 km) or more. This series uses an improved Centaur upper stage – the world’s first high-energy propellant stage – to increase its payload capability. Atlas II also has lower-cost electronics,^{[citation needed]} an improved flight computer^{[citation needed]} and longer propellant tanks than its predecessor, Atlas I.

The most powerful derivative is the Atlas IIAS.

[edit] Background

Atlas IIs are launched from Cape Canaveral Air Force Station, Fla., by the 45th Space Wing. The final West Coast Atlas II launch was accomplished December 2003 by the 30th Space Wing, Vandenberg AFB, Calif.

The Atlas was originally fielded as an ICBM in the late 1950s. On Oct. 31, 1959, the first Atlas, a D model stored horizontally, was placed on alert at Vandenberg AFB by the 576th Strategic Missile Squadron. Atlas E and F models were the first ICBMs to be stored vertically in underground silos and raised by elevators to an above-ground position for launch. The Air Force replaced the Atlas ICBMs with Titan ICBMs and converted the E and F models into space launch vehicles in the late 1960s. The last refurbished Atlas vehicle was launched from Vandenberg AFB in 1995 carrying a satellite for the Defense Meteorological Satellite Program.

NASA used the Atlas as a space launch vehicle as early as 1958. Atlas served as the launch vehicle for Project Score, an instrumentation package developed by the U.S. Army Signal Corps that became the world’s first communications satellite. The satellite broadcast President Eisenhower’s pre-recorded Christmas message around the world.

An Atlas booster carried astronaut John Glenn into orbit under Project Mercury, the first US manned space program. Atlas Centaur vehicles also launched Mariner and Pioneer planetary probes.

In May 1988, the Air Force chose General Dynamics (now Lockheed-Martin) to develop the Atlas II vehicle, primarily to launch Defense Satellite Communications System payloads and for commercial users as a result of Atlas I launch failures in the late 1980s.

• General Characteristics
  • Primary function: Launch vehicle
  • Primary contractor: Lockheed Martin - airframe, assembly, avionics, test and systems integration
  • Principal subcontractors: Rocketdyne (Atlas engine, MA-5); Pratt & Whitney (Centaur engine, RL-10) and Honeywell & Teledyne (avionics)
  • Power Plant: Three MA-5A Rocketdyne engines, two Pratt & Whitney RL10A-4 Centaur engines
  • Thrust: 494,500 lbf (2,200 kN)
  • Length: Up to 156 ft (47.54 m); 16 ft (4.87 m) high engine cluster
  • Core Diameter: 10 feet (3.04 m)
  • Gross Liftoff Weight: 414,000 lb (204,300 kg)
  • First Launch: February 10, 1992
  • Models: II, IIA, and IIAS
  • Launch Site: Cape Canaveral AFS, Florida
  • Inventory: unavailable

[edit] References

• USAF Atlas II Fact Sheet

[edit] External links

• NASA page on Atlas IIAS Vehicle
• Animation of the Atlas-IIAS launch and Terra satellite deployment