Centaur top stage

USA

Centaur on Atlas

The Centaur top-stage was the first cryogenic rocket stage. The Pratt & Whitney RL10 engine consuming liquid oxygen and hydrogen had a long and difficult development. Its design started in 1958. It first flew in 1962 but didn't launch a real payload before 1966. The Centaur stage was designed to be used by Atlas. It was 3.05 m in diameter and 9.1 m in length. In its operational version it was equipped with two RL10 A-3-3 engines with a thrust of 66.7 kN each. It carried 13.8 tons propellant and could burn during 450 seconds with several ignitions.

In the late-70ies the Atlas Centaur program was to be abandonned since NASA had decided to transfer all launches to the Shuttle.
In fact STS was less available than expected and the Atlas launch program was resumed (with the help of Intelsat finances) with a simplified motor. On the RL10 A-3-3A (73.4 kN thrust) the turbopump feeding was replaced by a pressurized tank system. This new Centaur was first launched in 1984 with an Atlas-G (streched by 2 meters). The GTO capacity then reached 2.3 tons.

In 1987 the augmented Atlas Centaur was selected by the USAF as the MLV2 standard launcher. This new launcher is refered to as Atlas-2. The first stage was streched by 2.7 m and the second stage by 0.9 m. This new Centaur takes 16.8 tons of propellant and can burn up to 473 seconds. Atlas-2A is different by its second stage RL10 A-4 engines with deployable nozzle. Atlas-2AS is still more powerful. It is made from Atlas-2A to which two pairs of Castor-4A boosters are added. Each pair ignites one after the other. Thus GTO capacity raises to 2.8, 3.1 and 3.7 tons respectively for Atlas 2, 2A and 2AS.

Evolution of Centaur's propulsion system:

Designation	First launch	Main engine Thrust (kN)	Main engineSI (sec.)	Applications
RL10 A-1	1962	66.7	425	Tests
RL10 A-3-1	1963	66.7	431	Atlas Centaur
RL10 A-3-3	1966	66.7	444	Atlas Centaur
RL10 A-3-3A	1984	73.4	446	Atlas-1 & -2
RL10 A-4	1991	92.6	449	Atlas-2A & -2AS

Statistics: the RL-10 motor made its 100th flight on the top stage Centaur of AC-114

Centaur on Titan:

Between 1974 and 1977, seven Centaur were used as top stages for Titan 3 rockets, designated as Titan 3E with no major transformation. In this configuration the Centaur was placed into the cap (4.1 m diameter) which provided the thermic protection. Those launchers were devoted to US and German probles and could send 3.6 tons to Mars or Venus.

In 1983 an agreement between NASA and USAF was reached to finance the development of a stage derived from Centaur to launch military satellites and probes from the Shuttle. This new cryogenic stage was a wide body of the Centaur to optimize the volume into the Shuttle's bay. The same motors remained so as the 3.05 m diamater liquid oxygen tank while the hydrogen tank was enhanced to 4.3 m diameter. Two versions of this new stage were developped: Centaur G of 6.1 m long for the USAF and a longer version named Centaur G-prime of 9.1 m long for NASA. After the Challenger accident usage of a cryogenic stage was prohibited for security reasons.

The Centaur G-prime was then adapted to the Titan 4. This version is 4.5 m diameter and about 9 m long. It weighs 26 tons including 23 tons propellant. The motors are RL10-3-3A of 73.4 kN which can operate for up to 617 seconds. The Titan 4 with Centaur top stage is designated Titan 401. It can orbit 4.5 tons in GEO. An enhanced version with Hercules SRMU boosters will enable to place 5.8 tons on such orbits.

External links:

#7, Jonathan lists: Centaur stage listing

Rockets with Centaur top stage:

Type Nr	Launch Vehicle	Serial Nr	Launch Date	Launch Site	ID Year	Payload	Comment
1	Atlas-LV3C Centaur-A	AC 1	8/05/1962	CC, LC-36A	1962-A74	Centaur AC-1	Failure
1	Atlas-LV3C Centaur-B	AC-2	27/11/1963	CC, LC-36A	1963-047	Centaur-AC 2
1	Atlas-LV3C Centaur-C	AC-3	30/06/1964	CC, LC-36A	1964-F09	Centaur-AC 3	Failure
2	Atlas-LV3C Centaur-C	AC-4	11/12/1964	CC, LC-36A	1964-082	Surveyor-Model 1
1	Atlas-LV3C Centaur-D	AC-5	2/03/1965	CC, LC-36A	1965-F04	Surveyor-SD 1	Failure
2	Atlas-LV3C Centaur-D	AC-6	11/08/1965	CC, LC-36B	1965-064	Surveyor-SD 2
3	Atlas-LV3C Centaur-D	AC-8	8/04/1966	CC, LC-36B	1966-030	Surveyor-SD 3
4	Atlas-LV3C Centaur-D	AC-10	30/05/1966	CC, LC-36A	1966-045	Surveyor 1
5	Atlas-LV3C Centaur-D	AC-7	20/09/1966	CC, LC-36A	1966-084	Surveyor 2
6	Atlas-LV3C Centaur-D	AC-9	26/10/1966	CC, LC-36B	1966-095	Surveyor-SD 4
7	Atlas-LV3C Centaur-D	AC-12	17/04/1967	CC, LC-36B	1967-035	Surveyor 3
8	Atlas-LV3C Centaur-D	AC-11	14/07/1967	CC, LC-36A	1967-068	Surveyor 4
1	Atlas-SLV3C Centaur-D	AC-13	8/09/1967	CC, LC-36B	1967-084	Surveyor 5
2	Atlas-SLV3C Centaur-D	AC-14	7/11/1967	CC, LC-36B	1967-112	Surveyor 6
3	Atlas-SLV3C Centaur-D	AC-15	7/01/1968	CC, LC-36A	1968-001	Surveyor 7
4	Atlas-SLV3C Centaur-D	AC-17	10/08/1968	CC, LC-36A	1968-068	ATS 4	Partial Failure
5	Atlas-SLV3C Centaur-D	AC-16	7/12/1968	CC, LC-36B	1968-110	OAO 2
6	Atlas-SLV3C Centaur-D	AC-20	25/02/1969	CC, LC-36B	1969-014	Mariner 6	Marsprobe
7	Atlas-SLV3C Centaur-D	AC-19	27/03/1969	CC, LC-36A	1969-030	Mariner 7
8	Atlas-SLV3C Centaur-D	AC-18	12/08/1969	CC, LC-36A	1969-069	ATS 5
9	Atlas-SLV3C Centaur-D	AC-21	30/11/1970	CC, LC-36B	1970-U03	OAO B	Failure
10	Atlas-SLV3C Centaur-D	AC-25	26/01/1971	CC, LC-36A	1971-006	Intelsat-4 2
11	Atlas-SLV3C Centaur-D	AC-24	9/05/1971	CC, LC-36A	1971-F04	Mariner 8	Failure
12	Atlas-SLV3C Centaur-D	AC-23	30/05/1971	CC, LC-36B	1971-051	Mariner 9
13	Atlas-SLV3C Centaur-D	AC-26	20/12/1971	CC, LC-36A	1971-116	Intelsat-4 3
14	Atlas-SLV3C Centaur-D	AC-28	23/01/1972	CC, LC-36B	1972-003	Intelsat-4 4
1	Atlas-SLV3C Centaur-D Star-37E	AC-27	3/03/1972	CC, LC-36A	1972-012	Pioneer 10
15	Atlas-SLV3C Centaur-D	AC-29	13/06/1972	CC, LC-36B	1972-041	Intelsat-4 5
16	Atlas-SLV3C Centaur-D	AC-22	21/08/1972	CC, LC-36B	1972-065	OAO 3
1	Atlas-SLV3D Centaur-D1A Star-37E	AC-30	6/04/1973	CC, LC-36B	1973-019	Pioneer 11
1	Atlas-SLV3D Centaur-D1A	AC-31	23/08/1973	CC, LC-36A	1973-058	Intelsat-4 7
2	Atlas-SLV3D Centaur-D1A	AC-34	3/11/1973	CC, LC-36B	1973-085	Mariner 10	Mercuryprobe
1	Titan-3E Centaur-D1T	3E-1/ TC-1	11/02/1974	CC, LC-41	1974-F01	SPHINX	Failure
3	Atlas-SLV3D Centaur-D1A	AC-32	21/11/1974	CC, LC-36B	1974-093	Intelsat-408
1	Titan-3E Centaur-D1T Star-37E	3E-2/ TC-2	10/12/1974	CC, LC-41	1974-097	Helios 1
4	Atlas-SLV3D Centaur-D1A	AC-33	20/02/1975	CC, LC-36A	1975-F01	Intelsat-4 6	Failure
5	Atlas-SLV3D Centaur-D1A	AC-35	22/05/1975	CC, LC-36A	1975-042	Intelsat-4 1
2	Titan-3E Centaur-D1T	3E-4/ TC-4	20/08/1975	CC, LC-41	1975-075	Viking 1
3	Titan-3E Centaur-D1T	3E-3/ TC-3	9/09/1975	CC, LC-41	1975-083	Viking 2
1	Atlas-SLV3D Centaur-D1AR	AC-36	26/09/1975	CC, LC-36B	1975-091	Intelsat-4A 1
2	Titan-3E Centaur-D1T Star-37E	3E-5/ TC-5	15/01/1976	CC, LC-41	1976-003	Helios 2
2	Atlas-SLV3D Centaur-D1AR	AC-37	29/01/1976	CC, LC-36B	1976-010	Intelsat-4A 2
3	Atlas-SLV3D Centaur-D1AR	AC-38	13/05/1976	CC, LC-36A	1976-042	Comstar 1A
4	Atlas-SLV3D Centaur-D1AR	AC-40	22/07/1976	CC, LC-36B	1976-073	Comstar 1B
5	Atlas-SLV3D Centaur-D1AR	AC-39	26/05/1977	CC, LC-36A	1977-041	Intelsat-4A 4
6	Atlas-SLV3D Centaur-D1AR	AC-45	12/08/1977	CC, LC-36B	1977-075	HEAO 1
4	Titan-3E Centaur-D1T	3E-7/ TC-7	20/08/1977	CC, LC-41	1977-076	Voyager 2
5	Titan-3E Centaur-D1T	3E-6/ TC-6	5/09/1977	CC, LC-41	1977-084	Voyager 1
7	Atlas-SLV3D Centaur-D1AR	AC-43	30/09/1977	CC, LC-36A	1977-F05	Intelsat-4A 5	Failure
8	Atlas-SLV3D Centaur-D1AR	AC-46	7/01/1978	CC, LC-36B	1978-002	Intelsat-4A 3
9	Atlas-SLV3D Centaur-D1AR	AC-44	9/02/1978	CC, LC-36A	1978-016	Fleetsatcom 1
10	Atlas-SLV3D Centaur-D1AR	AC-48	31/03/1978	CC, LC-36B	1978-035	Intelsat-4A 6
11	Atlas-SLV3D Centaur-D1AR	AC-50	20/05/1978	CC, LC-36A	1978-051	Pioneer 12	Venusprobe
12	Atlas-SLV3D Centaur-D1AR	AC-41	29/06/1978	CC, LC-36B	1978-068	Comstar 3
13	Atlas-SLV3D Centaur-D1AR	AC-51	8/08/1978	CC, LC-36A	1978-078	Pioneer 13	Venusprobe
14	Atlas-SLV3D Centaur-D1AR	AC-52	13/11/1978	CC, LC-36B	1978-103	HEAO 2
15	Atlas-SLV3D Centaur-D1AR	AC-47	4/05/1979	CC, LC-36A	1979-038	Fleetsatcom 2
16	Atlas-SLV3D Centaur-D1AR	AC-53	20/09/1979	CC, LC-36B	1979-082	HEAO 3
17	Atlas-SLV3D Centaur-D1AR	AC-49	18/01/1980	CC, LC-36A	1980-004	Fleetsatcom 3
18	Atlas-SLV3D Centaur-D1AR	AC-57	31/10/1980	CC, LC-36A	1980-087	Fleetsatcom 4
19	Atlas-SLV3D Centaur-D1AR	AC-54	6/12/1980	CC, LC-36B	1980-098	Intelsat-5 2
20	Atlas-SLV3D Centaur-D1AR	AC-42	21/02/1981	CC, LC-36A	1981-018	Comstar 1D
21	Atlas-SLV3D Centaur-D1AR	AC-56	23/05/1981	CC, LC-36B	1981-050	Intelsat-5 1
22	Atlas-SLV3D Centaur-D1AR	AC-59	6/08/1981	CC, LC-36A	1981-073	Fleetsatcom 5
23	Atlas-SLV3D Centaur-D1AR	AC-55	15/12/1981	CC, LC-36B	1981-119	Intelsat-503
24	Atlas-SLV3D Centaur-D1AR	AC-58	5/03/1982	CC, LC-36B	1982-017	Intelsat-5 4
25	Atlas-SLV3D Centaur-D1AR	AC-60	28/09/1982	CC, LC-36B	1982-097	Intelsat-5 5
26	Atlas-SLV3D Centaur-D1AR	AC-61	19/05/1983	CC, LC-36A	1983-047	Intelsat-506
1	Atlas-G Centaur D-1AR	AC-62/5042G	9/06/1984	CC, LC-36B	1984-057	Intelsat-509
2	Atlas-G Centaur D-1AR	AC-63/5043G	22/03/1985	CC, LC-36B	1985-025	Intelsat-5A 10
3	Atlas-G Centaur D-1AR	AC-64/5044G	30/06/1985	CC, LC-36B	1985-055	Intelsat-5A 11
4	Atlas-G Centaur D-1AR	AC-65/5045G	28/09/1985	CC, LC-36B	1985-087	Intelsat-5A 12
5	Atlas-G Centaur D-1AR	AC-66/5046G	5/12/1986	CC, LC-36B	1986-096	FLTSATCOM 7
6	Atlas-G Centaur D-1AR	AC-67/5048G	26/03/1987	CC, LC-36B	1987-F02	Fleetsatcom 6	Failure
7	Atlas-G Centaur D-1AR	AC-68	25/09/1989	CC, LC-36B	1989-077	FLTSATCOM 8
1	Titan-4(01)A Centaur-T	K-10/TC-12	7/02/1994	CC, LC-40	1994-009	Milstar-1 1
2	Titan-4(01)A Centaur-T	K-7/TC-10	3/05/1994	CC, LC-41	1994-026	Trumpet 1
3	Titan-4(01)A Centaur-T	K-9/TC-11	27/08/1994	CC, LC-41	1994-054	Mercury 1
4	Titan-4(01)A Centaur-T	K-23/TC-17	14/05/1995	CC, LC-40	1995-022	Mentor 1
5	Titan-4(01)A Centaur-T	K-19/TC-8	10/07/1995	CC, LC-41	1995-034	Trumpet 2
6	Titan-4(01)A Centaur-T	K-21/TC-13	6/11/1995	CC, LC-40	1995-060	Milstar-1 2
7	Titan-4(01)A Centaur-T	K-16/TC-15	24/04/1996	CC, LC-41	1996-026	Mercury 2
1	Titan-4(01)B Centaur-T	B-33/TC-21	15/10/1997	CC, LC-40	1997-061	Cassini, Huygens
8	Titan-4(01)A Centaur-T	A-17/TC-16	8/11/1997	CC, LC-41	1997-068	Trumpet 3
2	Titan-4(01)B Centaur-T	B-25/TC-18	9/05/1998	CC, LC-40	1998-029	Mentor 2
9	Titan-4(01)A Centaur-T	A-20/TC-9	12/08/1998	CC, LC-41	1998-F02	Mercury 3	Failure
3	Titan-4(01)B Centaur-T	B-32/TC-14	30/04/1999	CC, LC-40	1999-023	Milstar-2 1
4	Titan-4(01)B Centaur-T	B-41/TC-22	27/02/2001	CC, SLC-40	2001-009	Milstar-2 2
5	Titan-4(01)B Centaur-T	B-38/TC-19	16/01/2002	CC, SLC-40	2002-001	Milstar-2 3
6	Titan-4(01)B Centaur-T	B-35/TC-23	8/04/2003	CC, SLC-40	2003-012	Milstar-2 4
7	Titan-4(01)B Centaur-T	B-36/TC-20	9/09/2003	CC, SLC-40	2003-041	Mentor 3
1	Vulcan Centaur VC2S	V-001	8/01/2024	CC, SLC-41	2024-006	Peregrine 1
2	Vulcan Centaur VC2S	V-002	4/10/2024	CC, SLC-41	2024-179	Cert 2
3	Vulcan Centaur VC4S	V-003	13/08/2025	CC, SLC-41	2025-173	NTS-3 (USSF 106)

Note:

- All launches from
- All "Launch Date" are in UTC time.

Ref.: #0 - update: 07.02.2026

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