Atlas II

Infobox rocket


imsize = 150
caption = Launch of an Atlas II rocket. (NASA)
name = Atlas II
function = Medium expendable Launch vehicle
manufacturer = Lockheed Martin
country-origin = United States
height = 47.54 m
alt-height = 156 ft
diameter = 3.04 m
alt-diameter = 10 ft
mass = 204,300 kg
alt-mass = 414,000 lb
stages = 3.5
LEO-payload = 6,580 kg
alt-LEO =
payload-location = GTO
payload = 2,810 kg
alt-payload =
status = Retired
sites = LC-36, CCAFS
SLC-3 Vandenberg AFB
launches = 63
10 Atlas II
23 Atlas IIA
20 Atlas IIAS
success = 63
fail =
partial =
first=Atlas II: 7 December 1991
Atlas IIA: 10 June 1992
Atlas IIAS: 16 December 1993
last=Atlas II: 16 March 1998
Atlas IIA: 5 December 2002
Atlas IIAS 31 August 2004
payloads = SOHO (Atlas IIAS)
TDRS (Atlas IIA)
boosters =4
diff = Atlas IIAS
boostername = Castor 4A
boosterengines =1 Solid
boosterthrust =478.3 kN
alt-boosterthrust =107,530 lb_f
boosterSI =266 sec
boostertime =56 seconds
boosterfuel =Solid
alt-boosters =1
alt-diff =all
alt-boostername =MA-5
alt-boosterengines =2 RS-58-OBA
alt-boostersthrust =2,093.3 kN
alt-alt-boosterthrust =470,680 lb_f
alt-boosterSI =299 sec
alt-boostertime =172 seconds
alt-boosterfuel =LOX/RP-1
stage1name =
stage1engines = 1 RS-58-OSA
stage1thrust = 386 kN
alt-stage1thrust = 86,844 lb_f
stage1time = 283 seconds
stage1SI = 316 sec
stage1fuel = RP-1/LOX
stage2name = Centaur
stage2engines = 2 RL-10A
stage2thrust = 147 kN
alt-stage2thrust = 41,592 lb_f
stage2time = 392 seconds
stage2SI = 449 sec
stage2fuel = LH2/LOX
stage3name = IABS (optional)
stage3engines = 1 R-4D
stage3thrust = 980N
alt-stage3thrust = 220 lb_f
stage3time = 60 seconds
stage3SI = 312 sec
stage3fuel = 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.)

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,Fact|date=February 2007 an improved flight computerFact|date=February 2007 and longer propellant tanks than its predecessor, Atlas I.

The most powerful derivative is the Atlas IIAS.

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

References

* [http://www.af.mil/factsheets/factsheet.asp?fsID=80 USAF Atlas II Fact Sheet]

External links

* [http://www.grc.nasa.gov/WWW/PAO/html/atlas2as.htm NASA page on Atlas IIAS Vehicle]
* [http://terra.nasa.gov/About/SC/launch_composite.html Animation of the Atlas-IIAS launch and Terra satellite deployment]