Atlas-Centaur

Atlas-Centaur

An Atlas-Centaur launching Surveyor 1
Function	Expendable launch system
Manufacturer	Convair General Dynamics
Country of origin	United States
Launch history
Status	Retired
Launch sites	LC-36, Cape Canaveral and Vandenberg Space Launch Complex-3 East
Total launches	167
Successes	152
Failures	13
Partial failures	2
First flight	8 May 1962
Last flight	31 August 2004

The Atlas-Centaur was an American expendable launch system derived from the SM-65 Atlas D missile. Launches were conducted from Launch Complex 36 at Cape Canaveral Air Force Station, Florida.

Early development and testing

Convair, the manufacturer of the Atlas, developed the Centaur upper stage specifically for that booster, sharing its inflated balloon skin. It was also the first production rocket stage to utilize liquid hydrogen and liquid oxygen as propellant. Despite high performance, LH2 nonetheless had problems because it had to be chilled at extremely low temperatures (lower than LOX) and its light molecular density meant that large fuel tanks were needed.

The first attempt at using a LH2/LOX-fueled engine was the Air Force's top-secret Lockheed CL-400 Suntan reconnaissance aircraft program in the mid-1950s, but it was judged too unsafe, expensive, and impractical for that purpose. However, the progress made during the aborted venture was picked up by Convair and others for rocket stage use.

Convair developed a specially-enhanced version of the Atlas D vehicle for mating with Centaur stages; the Atlas's engines were upgraded and the structure reinforced for the large upper stage, along with elongated fuel tanks. The first Atlas-Centaur, Vehicle F-1, arrived at Cape Canaveral in February 1961 and was erected at the newly-completed LC-36A, a pad built specifically for A/C flights. However, technical problems and other delays caused it to sit there for 18 months. The mission at last got under way on 8 May 1962. Everything went without incident until about T+53 seconds when the Centaur stage ruptured and disintegrated, taking the Atlas with it in a matter of seconds.

The failure was determined to be caused by an insulation panel that ripped off the Centaur during ascent, causing the LH2 tank to overheat and eventually explode, leading to the complete destruction of the launch vehicle. The panel had been meant to jettison at 50 miles up when the air was thinner, but the mechanism holding it in place was designed inadequately and lead to premature separation. Testing was suspended while efforts were made to correct the Centaur's design flaws. A Congressional investigation in June called the overall management of the Centaur program "weak" and Wernher von Braun recommended that it be cancelled in favor of a Saturn I with an Agena upper stage for planetary missions. In addition, the production Centaur stage had less lift capacity than originally planned, leading to ARPA cancelling Project Advent. NASA transferred Centaur development from MSFC to the Lewis Center in Ohio where a team headed by Abe Silverstein worked to correct the insulation panel problems and various other design flaws.

More than a year later, the second test took place in November 1963 a few days after President Kennedy's assassination. The redesigned Centaur stage functioned without any problems, reaching a low Earth orbit, firing its engine again, and moving to a geosynchronous orbit.

Flight number three (which carried a dummy Surveyor probe) in June 1964 was a partial success. The Centaur reached orbit, but could not be restarted due to a fuel leak. Flight four (December 1964) was completely successful.

The 5th flight on 2 March 1965 proved a complete disaster as the Atlas's fuel prevalves accidentally snapped shut one second after liftoff, causing the booster to fall back onto LC-36A in the biggest pad explosion ever seen at Cape Canaveral. As a result, NASA was forced to finish work on LC-36B, constructed as a backup pad, but abandoned when it was 90% completed.

Afterwards, A/C failures were rare and mostly high-altitude ones that occurred late in the launch (exceptions being failed launches of weather satellites in September 1977 and March 1987). With the retirement of the Agena stage in 1980, all Atlases flown from that point onwards were paired with Centaurs except for a few military flights involving decommissioned Atlas E/F missiles.

Originally designed and built by Convair Division of General Dynamics in San Diego, California, production of Atlas Centaurs at Convair ended in 1995 but was resumed at Lockheed-Martin in Colorado. The list of Atlas Centaur ID numbers began with AC-1 launched on 8 May 1962 and ended with the last Atlas III (Centaur), AC-206, launched on 3 February 2005.

The Rocketdyne-powered Atlas-Centaur was sometimes referred to as a 2¹/₂ stage launch vehicle because the Atlas first stage (in most cases) jettisoned the twin-thrust-chamber booster engine prior to the completion of the first stage burn. Atlas Centaurs with a Rocketdyne-powered first stage were used for 167 launches between 1962 and 2004 by which time they had been superseded by Atlas Vs with a new first stage powered by a much more powerful Russian RD-180 engine. (Atlas Vs are not generally referred to as "Atlas Centaurs" and do not share the AC- serial numbers of the original Atlas Centaurs that had the Rocketdyne-powered first stages.)

Initially, a modified Atlas D, designated LV-3C, was used as the first stage This was quickly replaced by SLV-3C, and later the SLV-3D, both derived from the standard Atlas SLV-3 rocket. Two spaceflights, with the Pioneer 10 and Pioneer 11 space probes to Jupiter, Saturn and exiting the Solar System, used a spin-stabilized "Star-37E" solid propellant final stage weighing 2473 pounds and contributing 8000 mph to the velocities of the spacecraft.

The fifth launch of an Atlas-Centaur exploded on the launch pad, causing significant damage, and persuading NASA and the Air Force to proceed with the completion of a previously abandoned back-up launch pad at Launch Complex-36B. Such launch failures turned out to be very rare during the use of the Atlas-Centaur rocket, and its successors.

Variants

Name	First launch	Last launch	Launches	Successes	Failures	Partial failures	Remarks
Atlas LV-3C Centaur-A	1962-05-08		1	0	1	0
Atlas LV-3C Centaur-B	1963-11-27		1	1	0	0
Atlas LV-3C Centaur-C	1964-06-30	1965-03-03	3	0	2	1
Atlas LV-3C Centaur-D	1965-08-11	1967-07-14	7	7	0	0
Atlas SLV-3C Centaur-D	1967-09-08	1972-08-21	17	14	3	0	One flight with Star-37E upper stage
Atlas SLV-3D Centaur-D1A	1973-04-06	1975-05-22	6	5	1	0	One flight with Star-37E upper stage
Atlas SLV-3D Centaur-D1AR	1975-09-26	1983-05-19	26	24	1	1
Designations for later model Atlas Centaurs
Atlas G	1984-06-09	1989-09-25	7	5	2	0	(Atlas G Centaur-D1AR)
Atlas I	1990-07-25	1997-04-25	11	8	3	0
Atlas IIA/IIAS	1991-12-07	2004-08-31	63	63	0	0
Designations for Russian powered Atlases with Centaur 2nd stage
Atlas III	2000-05-24	2005-02-03	6	6	0	0
Atlas V	2002-08-21	Active	14	13	0	1