American rocket
Atlas II
![](//upload.wikimedia.org/wikipedia/commons/thumb/2/2f/DF-SC-99-00074_cropped_and_rotated.jpeg/220px-DF-SC-99-00074_cropped_and_rotated.jpeg) Launch of an Atlas II rocket
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Function
| Medium expendable
Launch vehicle
|
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Manufacturer
| Lockheed Martin
|
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Country of origin
| United States
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Height
| 47.54 m (156.0 ft)
|
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Diameter
| 3.04 m (10.0 ft)
|
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Mass
| 204,300 kg (450,400 lb)
|
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Stages
| 2.5 (3.5 with
IABS
)
|
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|
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Mass
|
- Atlas II
: 6,580 kg (14,510 lb)
- Atlas IIA
: 7,280 kg (16,050 lb)
- Atlas IIAS
: 8,610 kg (18,980 lb)
[1]
|
---|
|
Mass
|
- Atlas II
: 2,810 kg (6,190 lb)
- Atlas IIA
: 3,039 kg (6,700 lb)
- Atlas IIAS
: 3,630 kg (8,000 lb)
[1]
|
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Family
| Atlas
|
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Status
| Retired
|
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Launch sites
| SLC-36
,
Cape Canaveral
SLC-3
Vandenberg AFB
|
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Total launches
| 63
(
II:
10,
IIA:
23,
IIAS:
30)
|
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Success(es)
| 63
(
II:
10,
IIA:
23,
IIAS:
30)
[2]
|
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First flight
| II:
December 7, 1991
IIA:
June 10, 1992
IIAS:
December 16, 1993
|
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Last flight
| II:
March 16, 1998
IIA:
December 5, 2002
IIAS:
August 31, 2004
[2]
|
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Type of passengers/cargo
| SOHO
(Atlas IIAS)
TDRS
(Atlas IIA)
|
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|
Stage info
|
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No. boosters
| 4
|
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Powered by
| 1
Solid
|
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Maximum thrust
| 478.3 kN (107,500 lb
f
)
|
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Specific impulse
| 266 s (2.61 km/s)
|
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Burn time
| 56 seconds
|
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Propellant
| HTPB
[3]
|
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|
No. boosters
| 1
|
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Powered by
| 2
RS-56
-OBA
|
---|
Maximum thrust
| 2,093.3 kN (470,600 lb
f
)
|
---|
Specific impulse
| 299 s (2.93 km/s)
|
---|
Burn time
| 172 seconds
|
---|
Propellant
| RP-1
/
LOX
|
---|
|
Powered by
| 1
RS-56
-OSA
|
---|
Maximum thrust
| 386 kN (87,000 lb
f
)
|
---|
Specific impulse
| 316 s (3.10 km/s)
|
---|
Burn time
| 283 seconds
|
---|
Propellant
| RP-1
/
LOX
|
---|
|
Powered by
| 2
RL-10
A
|
---|
Maximum thrust
| 147 kN (33,000 lb
f
)
|
---|
Specific impulse
| 449 s (4.40 km/s)
|
---|
Burn time
| 392 seconds
|
---|
Propellant
| LH
2
/
LOX
|
---|
|
Powered by
| 2
R-4D
|
---|
Maximum thrust
| 980 N (220 lb
f
)
|
---|
Specific impulse
| 312 s (3.06 km/s)
|
---|
Burn time
| 60 seconds
|
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Propellant
| N
2
O
4
/
MMH
|
|
|
Atlas II
was a member of the
Atlas
family of
launch vehicles
, which evolved from the successful
Atlas missile
program of the 1950s. The Atlas II was a direct evolution of the
Atlas I
, featuring longer first-stage tanks, higher-performing engines, and the option for strap-on solid rocket boosters. It was designed to launch payloads into
low Earth orbit
, geosynchronous transfer orbit or geosynchronous orbit. Sixty-three launches of the Atlas II, IIA and IIAS models were carried out between 1991 and 2004; all sixty-three launches were successes, making the Atlas II a highly reliable space launch system. The Atlas line was continued by the
Atlas III
, used between 2000 and 2005, and the
Atlas V
, which is still in use as of 2024
[update]
.
Background
[
edit
]
In May 1988, the US Air Force chose
General Dynamics
(now
Lockheed Martin
) to develop the Atlas II vehicle, primarily to launch
Defense Satellite Communications System
payloads under the Medium Launch Vehicle II (MLV-II) program.
[4]
Additional commercial and U.S. Government sales resulted in production increases leading to greater than 60 vehicles being produced and launched.
Atlas II was developed from the
Atlas I
and featured numerous upgrades over that vehicle.
[5]
Atlas II was launched from
Launch Complex 36
at
Cape Canaveral Space Force Station
in Florida as well as
Space Launch Complex 3E
at
Vandenberg Space Force Base
in California. All launches were successful.
Design
[
edit
]
Atlas II provided higher performance than the earlier
Atlas I
by using engines with greater thrust and longer propellant tanks for both stages. The increased thrust, engine efficiency, and propellant capacity enabled the vehicle to lift payloads of 6,100 pounds (2,767 kg) into geostationary transfer orbit (GTO), or more on later Atlas II variants.
[5]
Atlas II also featured lower-cost electronics, an improved flight computer, and longer propellant tanks than its predecessor,
Atlas I
.
[6]
Atlas II first stage
[
edit
]
Workers at Cape Canaveral Air Force Station prepare to erect the first stage of an Atlas IIA rocket in the launch gantry on Pad 36A ahead of the GOES-L launch. Visible are the
RS-56
rocket engines.
The Atlas II first stage was 3.05 m (10.0 ft) in diameter and 24.90 m (81.7 ft) long. The stage was powered by 3
RS-56
rocket engines (derived from the
RS-27
main engine of the
Delta II
rocket) burning 156 t (344,000 lb) of
RP-1
and
liquid oxygen
. The two booster engines were the RS-56-OBA variants (the complete assembly of both engines and the aft skirt was referred to as the MA-5A), with high thrust but moderate efficiency. The sustainer (center) engine was the RS-56-OSA variant, featuring much less thrust but higher efficiency at high altitudes than the booster engines.
The
vernier engines
used on the first stage of the Atlas I (and all previous Atlas models) were replaced by a
hydrazine
-fueled roll control system on Atlas II. This system, mounted on the interstage between the first and second stages, utilized small thrusters to control the vehicle's roll.
[1]
[7]
[8]
Compared to
Atlas I
, the Atlas II first stage was 2.7 m (8 ft 10 in) taller.
[9]
The Atlas II was the last Atlas rocket to use the "stage-and-a-half" technique, where it ignited all 3
RS-56
engines at liftoff and then jettisoned the 2 RS-56-OBA side engines and their support structure during ascent. The two RS-56-OBA engines were integrated into a single unit called the
MA-5A
and shared a common
gas generator
. They burned for approximately 164 seconds before being jettisoned, when acceleration reached approximately 5.0?5.5
g
. The central sustainer engine on the first stage, an RS-56-OSA, would burn for an additional 125 seconds after their jettison. It featured better efficiency at high altitudes than the RS-56-OBAs.
[10]
[7]
The first stage also had the option to be fitted with 4
Castor 4A
solid rocket boosters as part of the IIAS version, each providing an additional 478.3 kN (107,500 lb
f
) of thrust for 56 seconds. The first two boosters were ignited at liftoff, and the other two were ignited after the first two burnt out. Both pairs of boosters were jettisoned shortly after their respective burns.
[11]
Centaur II upper stage
[
edit
]
The second stage of Atlas II, the Centaur II, was the result of over 3 decades of flights and enhancements of the Centaur upper stage. Centaur II featured 2
RL-10A-3-3A
engines, burning liquid hydrogen and liquid oxygen. It featured propellant tanks 0.9 meters longer than its predecessor, Centaur I, giving the stage more propellant and therefore higher performance. Due to the super cold propellants inside Centaur, foam insulation was installed onto the outer metal skin on the stage to help mitigate propellant boiloff inside the tank. Centaur II's foam insulation was permanently attached to the side of the stage, whereas previous versions of the stage (including Centaur I) jettisoned their insulation panels during flight.
[1]
The Centaur II upper stage (along with all other Centaur variants) used a pressure-stabilized propellant tank design and
cryogenic propellants
. The two stainless steel propellant tanks were separated by a common bulkhead, which helped keep mass down. Centaur II was 10.1 m (33 ft) long, carrying almost 17 t (37,000 lb) of fuel. The stage also featured 12 27 N (6.1 lbf)
hydrazine
thrusters to orient the stage and settle the propellants prior to engine ignition.
[7]
For the IIA and IIAS versions, Atlas used the Centaur IIA variant which featured 2
RL-10A-4
engines, providing higher thrust and efficiency over the RL-10A-3-3A. The two engines could be fitted with extendable nozzles, which would provide an increase in efficiency and therefore performance.
[12]
Centaur II was further refined to create the Centaur III, which flew on the
Atlas III
and continues to fly today on the
Atlas V
. Atlas II was the final Atlas rocket that only had a dual-engine Centaur available, future rockets had the option for one or two RL-10 engines on Centaur.
[13]
However, the Centaur V flying on the
Vulcan rocket
will only utilize two RL-10 engines.
[14]
- Centaur 2A pictures:
-
Centaur IIA arrives at Launch Complex 36A for the launch of
GOES-L
.
-
Centaur IIA before mating with Atlas II booster.
-
A close-up view of the RL-10 engines of Centaur IIA.
-
Centaur IIA, to be used to launch TDRS-I, is lifted for integration.
-
Centaur IIA for the TDRS-I mission is inspected in Hangar J at Cape Canaveral.
Integrated Apogee Boost Stage
[
edit
]
The Integrated Apogee Boost Stage was an optional upper stage, used only as an apogee kick stage when launching
Defense Satellite Communications System III
satellites (which were designed to be delivered directly to
geostationary orbit
using the
Transtage
or
Inertial Upper Stage
, and so were not capable of performing their own circularization burn at the apogee of their
geostationary transfer orbit
) on board the Atlas II and, later, the
Delta IV
. It was powered by two
R-4D
engines and could operate on-orbit for up to twelve days before deploying its payload, allowing additional flexibility in mission planning. The IABS measured 2.9 m in diameter, and 0.68 m in length, carrying 1303 kg of propellant with a dry mass of 275 kg.
Payload fairing
[
edit
]
Three fairing models were available for the Atlas II:
[7]
- Medium
, with a diameter of 3.3 m (11 ft), a height of 10.4 m (34 ft), and a mass of 1,409 kg (3,106 lb)
- Large
, with a diameter of 4.2 m (14 ft), a height of 12.2 m (40 ft), and a mass of 2,087 kg (4,601 lb)
- Extended
, with a diameter of 4.2 m (14 ft), a height of 13.1 m (43 ft), and a mass of 2,255 kg (4,971 lb)
The Medium variant was not commonly used for Atlas II but was often used in earlier Atlas rockets. The Large and Extended fairing options were also later used on the Atlas III and Atlas V rockets. For the Atlas V, these fairings were part of the 400-series of that rocket, and a further extended option ("Extra Extended") was available.
[15]
The 4-meter Atlas fairing last flew in 2022.
[16]
Atlas II rockets flying with a Medium fairing could move the most payload to orbit, as that fairing was the lightest. Similarly, rockets with Large or Extended fairings suffered slight hits to their payload capacity.
Versions
[
edit
]
The first stage of an Atlas IIA rocket is erected vertical at Cape Canaveral Pad 36A.
Atlas II was developed from the
Atlas I
and was available in 3 versions.
Atlas II
[
edit
]
The original Atlas II was based on the Atlas I and
its predecessors
. Its lengthened propellant tanks and improved electronics over the Atlas I offered better performance. It was designed to work as part of the US Air Force's Medium Launch Vehicle II program. This version flew between 1991 and 1998.
[1]
Atlas IIA
[
edit
]
Atlas IIA was a derivative of the Atlas II designed to service the commercial launch market. The main improvement was the switch from the
RL10A-3-3A
to RL10A-4 engine on the Centaur upper stage, increasing the stage's performance and the vehicle's payload capability.
[7]
The IIA version flew between 1992 and 2002.
[12]
Atlas IIAS
[
edit
]
Atlas IIAS was largely identical to IIA, but added four
Castor
4A solid rocket boosters to increase performance. These boosters were ignited in pairs, with one pair igniting on the ground, and the second igniting in the air shortly after the first pair separated. The half-stage booster section would then drop off as usual.
[7]
IIAS was used between 1993 and 2004, concurrently with IIA.
[11]
Specifications
[
edit
]
Atlas launch vehicle evolution, including the unflown Atlas V HLV (far right). (USAF)
- Primary contractor: Lockheed Martin ? airframe, assembly, avionics, test and systems integration
[17]
- Principal subcontractors: Rocketdyne (First stage engines), Pratt & Whitney (Centaur RL-10 engines), Honeywell & Teledyne (avionics), and Thiokol (Castor 4A SRBs)
[7]
- Power Plant: Two Rocketdyne RS-56-OBA engines (making up the MA-5A), one RS-56-OSA, two Pratt & Whitney RL-10A-3-3A or 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)
- Fairing options: 3 (Medium, Large, Extended)
[7]
- Models: II, IIA, and IIAS
- Launch Sites:
Cape Canaveral SFS
Launch Complex 36
,
Florida
and
Vandenberg Space Force Base
Space Launch Complex 3E
,
California
See also
[
edit
]
References
[
edit
]
- ^
a
b
c
d
e
"Atlas II"
. Astronautix. Archived from
the original
on October 15, 2002
. Retrieved
January 9,
2016
.
- ^
a
b
Tariq Malik
"Final Atlas 2 Rocket Orbits Classified U.S. Satellite"
,
Space News,
August 31, 2004 (Accessed September 24, 2014)
- ^
Wade, Mark.
"Castor 4A engine"
.
astronautix.com
. Archived from
the original
on December 28, 2016.
- ^
"General Dynamics will build a half-billion-dollar rocket fleet"
.
UPI.com
. May 3, 1988
. Retrieved
September 27,
2022
.
- ^
a
b
Harwood, William (December 7, 1991).
"Atlas-2 rocket launched on maiden launch"
.
UPI.com
. Retrieved
September 27,
2022
.
- ^
"Atlas II Factsheet"
.
au.af.mil
. Archived from
the original
on May 1, 2017
. Retrieved
September 20,
2018
.
- ^
a
b
c
d
e
f
g
h
"Atlas Launch System Payload Planner's Guide"
(PDF)
. Lockheed Martin. Archived from
the original
(PDF)
on April 21, 2015
. Retrieved
January 9,
2016
.
- ^
"Atlas Roll Control Module (ARCM)"
(PDF)
. Aerojet
. Retrieved
November 5,
2022
.
- ^
"Le lanceur Atlas 2"
.
www.capcomespace.net
(in French)
. Retrieved
February 14,
2021
.
- ^
"Atlas IIA(S) Data Sheet"
. Space Launch Report. Archived from the original on August 13, 2016
. Retrieved
January 9,
2016
.
{{
cite web
}}
: CS1 maint: unfit URL (
link
)
- ^
a
b
"Atlas IIAS"
. Astronautix. Archived from
the original
on May 1, 2002
. Retrieved
January 9,
2016
.
- ^
a
b
"Atlas IIA"
. Astronautix. Archived from
the original
on March 19, 2002
. Retrieved
January 9,
2016
.
- ^
"Atlas 3A"
.
- ^
"Vulcan"
.
- ^
"Atlas V"
.
- ^
"last-4m"
. November 10, 2022.
- ^
Spaceflight Now,
Atlas IIAS
(accessed September 24, 2014)
External links
[
edit
]
Atlas rockets
|
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Main articles
| | |
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Rockets
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Numerical
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Other
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Launch sites
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Components
| Boosters
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First stages
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Upper stages
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Engines
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Corporations
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Launches
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USAF
and
USSF
space vehicle designations (since 1962)
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SLV series
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SB series
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Satellites
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- 1
Not assigned
- 2
Unofficial designation
- 3
Designation believed to be this type but unconfirmed
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Current
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In development
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Retired
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Classes
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- This Template lists historical, current, and future space rockets that at least once attempted (but not necessarily succeeded in) an orbital launch or that are planned to attempt such a launch in the future
- Symbol
†
indicates past or current rockets that attempted orbital launches but never succeeded (never did or has yet to perform a successful orbital launch)
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Active
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In development
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Retired
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- * - Japanese projects using US rockets or stages
- ** - uses Russian engines
- †
- never succeeded
- ††
- no new orders accepted
- †††
- used Ukrainian first stage
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