Atlas II
Launch of an Atlas II rocket. (NASA)
Stages		4
0 - 0 Stage	Engines	RS-56-OBA x 2
Thrust		2,094 kN
Burn time		172 s
Fuels		Lox/Kerosene
1 - 1st Stage	Engines	RS-56-OSA x 1
Thrust		386 kN
Burn time		283 s
Fuels		Lox/Kerosene
2 - 2nd Stage	Engine	RL-10A-3A x 2
Thrust		147 kN
Burn time		488 s
Fuels		Lox/LH2
3 - 3rd Stage	Engine	R-4D
Thrust		980 N
Burn time		60 s
Fuels		N2O4/MMH
Launch Vehicle		1st Launch December 7, 1991
Payload LEO		6,580 kg
Payload GEO		2,810 kg

Mission

Atlas II is a member of the Atlas family of launch vehicles, which evolved from the successful Atlas intercontinental ballistic missile (ICBM) program. It is designed to launch payloads into low earth orbit, geosynchronous transfer orbit or geosynchronous orbit.

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, an improved flight computer and longer propellant tanks than its predecessor, Atlas I.

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 U.S. astronaut John Glenn into orbit under Project Mercury, the first U.S. 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 lb (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 (204,343 kg)
  • First Launch: Feb. 10, 1992
  • Models: II, IIA, and IIAS
  • Launch Site: Cape Canaveral AFS, Fla.
  • Inventory: unavailable

Atlas launch vehicle evolution. (USAF)

Reference

USAF Atlas II Fact Sheet (http://www.af.mil/factsheets/factsheet.asp?fsID=80)