Titan IV


Titan IV was a family of heavy-lift space launch vehicles developed by Martin Marietta and operated by the United States Air Force from 1989 to 2005.[4] Launches were conducted from Cape Canaveral Air Force Station, Florida[5] and Vandenberg Air Force Base, California.[6]

Titan IV
A Titan IV-B rocket carrying the Cassini-Huygens space research mission before takeoff from Launch Complex 40 on Cape Canaveral, 12 October 1997 (NASA)
FunctionHeavy-lift launch vehicle
ManufacturerLockheed Martin
Country of originUnited States
Cost per launch$432 million (USD)
Height50-62 m (164-207 ft)
Diameter3.05 m (10 ft)
Mass943,050 kg (2,079,060 lb)
Payload to LEO
Mass21,680 kg(47,790 lb)
Payload to Polar LEO
Mass17,600 kg(38,800 lb)
Payload to GSO
Mass5,760 kg(12,690 lb)
Payload to HCO
Mass5,660 kg(12,470 lb)
Associated rockets
ComparableAtlas V, Delta IV Heavy, Falcon 9
Launch history
Launch sitesSLC-40/41, Cape Canaveral
SLC-4E, Vandenberg AFB
Total launches39[1]
(IVA: 22, IVB: 17)
(IVA: 20, IVB: 15)
Failure(s)4 (IVA: 2, IVB: 2)
First flightIV-A: 14 June 1989
IV-B: 23 February 1997
Last flightIV-A: 12 August 1998
IV-B: 19 October 2005
Type of passengers/cargoLacrosse
Boosters (IV-A) – UA1207
No. boosters2
Powered byUnited Technologies UA1207
Maximum thrust14.234 MN (3,200,000 lbf)
Specific impulse272 seconds (2667 N·s/kg)
Burn time120 seconds
Boosters (IV-B) – SRMU
No. boosters2
Powered byHercules USRM[2]
Maximum thrust15.12 MN (3,400,000 lbf)
Specific impulse286 seconds (2805 N·s/kg)
Burn time140 seconds
First stage
Powered by2 LR87[3]
Maximum thrust2,440 kN (548,000 lbf)
Specific impulse302 seconds (2962 N·s/kg)
Burn time164 seconds
PropellantN2O4 / Aerozine 50
Second stage
Powered by1 LR91
Maximum thrust467 kN (105,000 lbf)
Specific impulse316 seconds (3100 N·s/kg)
Burn time223 seconds
PropellantN2O4 / Aerozine 50
Third stage (Optional) – Centaur-T
Powered by2 RL10
Maximum thrust147 kN (33,100 lbf)
Specific impulse444 seconds (4354 N·s/kg)
Burn time625 seconds

The Titan IV was the last of the Titan family of rockets, originally developed by the Glenn L. Martin Company in 1958. It was retired in 2005 due to their high cost of operation and concerns over its toxic hypergolic propellants, and replaced with the Atlas V and Delta IV launch vehicles under the EELV program. The final launch (B-30) from Cape Canaveral occurred on 29 April 2005, and the final launch from Vandenberg AFB occurred on 19 October 2005.[7] Lockheed Martin Space Systems built the Titan IVs near Denver, Colorado, under contract to the US government.[1]

Two Titan IV vehicles are currently on display at the National Museum of the United States Air Force in Dayton, Ohio and the Evergreen Aviation and Space Museum in McMinnville, Oregon.

Vehicle description


The Titan IV was developed to provide assured capability to launch Space Shuttle–class payloads for the Air Force. The Titan IV could be launched with no upper stage, the Inertial Upper Stage (IUS), or the Centaur upper stage.

The Titan IV was made up of two large solid-fuel rocket boosters and a two-stage liquid-fueled core. The two storable liquid fuel core stages used Aerozine 50 fuel and nitrogen tetroxide oxidizer. These propellants are hypergolic, igniting on contact, and are liquids at room temperature, so no tank insulation is needed. This allowed the launcher to be stored in a ready state for extended periods, but both propellants are extremely toxic.

The Titan IV could be launched from either coast: SLC-40 or 41 at Cape Canaveral Air Force Station near Cocoa Beach, Florida and at SLC-4E, at Vandenberg Air Force Base launch sites 55 miles northwest of Santa Barbara California. Launches to polar orbits occurred from Vandenberg, with most other launches taking place at Cape Canaveral.

Titan IV-A


Titan IV-A flew with steel-cased solid UA1207 rocket motors (SRMs) produced by Chemical Systems Division.[8][9][10]

Titan IV-B


The Titan IV-B evolved from the Titan III family and was similar to the Titan 34D.

While the launcher family had an extremely good reliability record in its first two decades, this changed in the 1980s with the loss of a Titan 34D in 1985 followed by the disastrous explosion of another in 1986 due to a SRM failure. Due to this, the Titan IV-B vehicle was intended to use the new composite-casing Upgraded Solid Rocket Motors.[11] Due to development problems the first few Titan IV-B launches flew with the old-style UA1207 SRMs.

General characteristics

  • Builder: Lockheed-Martin Astronautics
  • Power Plant:
    • Stage 0 consisted of two solid-rocket motors.
    • Stage 1 used an LR87-AJ-11 liquid-propellant rocket engine.
    • Stage 2 used the LR91-AJ-11 liquid-propellant engine.
    • Optional upper stages included the Centaur and Inertial Upper Stage.
  • Guidance System: A ring laser gyro guidance system manufactured by Honeywell.
  • Thrust:
    • Stage 0: Solid rocket motors provided 1.7 million pounds force (7.56 MN) per motor at liftoff.
    • Stage 1: LR87-AJ-11 provided an average of 548,000 pounds force (2.44 MN)
    • Stage 2: LR91-AJ-11 provided an average of 105,000 pounds force (467 kN).
    • Optional Centaur (RL10A-3-3A) upper stage provided 33,100 pounds force (147 kN) and the Inertial Upper Stage provided up to 41,500 pounds force (185 kN).
  • Length: Up to 204 feet (62 m)
  • Lift Capability:
    • Could carry up to 47,800 pounds (21,700 kg) into low Earth orbit
    • up to 12,700 pounds (5,800 kg) into a geosynchronous orbit when launched from Cape Canaveral AFS, Fla.;
    • and up to 38,800 pounds (17,600 kg) into a low Earth polar orbit when launched from Vandenberg AFB.
    • into geosynchronous orbit:
      • with Centaur upper stage 12,700 pounds (5,800 kg)
      • with Inertial Upper Stage 5,250 pounds (2,380 kg)
  • Payload fairing:[12]
    • Manufacturer: McDonnell Douglas Space Systems Co
    • Diameter: 16.7 feet (5.1 m)
    • Length: 56, 66, 76, or 86 ft
    • Mass: 11,000, 12,000, 13,000, or 14,000 lb
    • Design: 3 sections, isogrid structure, Aluminum
  • Maximum Takeoff Weight: Approximately 2.2 million pounds (1,000,000 kg)
  • Cost: Approximately $250–350 million, depending on launch configuration.
  • Date deployed: June 1989
  • Launch sites: Cape Canaveral AFS, Fla., and Vandenberg AFB, Calif.



Solid Rocket Motor Upgrade test stand


In 1988–89, The Ralph M. Parsons Company designed and built a full-scale steel tower and deflector facility, which was used to test the Titan IV Solid Rocket Motor Upgrade (SRMU).[13] The launch and the effect of the SRMU thrust force on the Titan IV vehicle were modeled. To evaluate the magnitude of the thrust force, the SRMU was connected to the steel tower through load measurement systems and launched in-place. It was the first full-scale test conducted to simulate the effects of the SRMU on the Titan IV vehicle.[14]

Proposed aluminum-lithium tanks


In the early 1980s, General Dynamics developed a plan to assemble a lunar landing spacecraft in-orbit under the name Early Lunar Access. A Space Shuttle would lift a lunar lander into orbit and then a Titan IV rocket would launch with a modified Centaur G-Prime stage to rendezvous and dock. The plan required upgrading the Space Shuttle and Titan IV to use lighter aluminium-lithium alloy propellant tanks.[15] The plan never came to fruition, but in the 1990s the Shuttle's External Tank was converted to aluminum-lithium tanks to rendezvous with the highly inclined orbit of the Russian Mir Space Station.[16]

Type identification


The IV-A (40nA) used boosters with steel casings, the IV-B (40nB) used boosters with composite casings (the SRMU).

Type 401 used a Centaur 3rd stage, type 402 used an IUS 3rd stage. The other 3 types (without 3rd stages) were 403, 404, and 405:

  • Type 403 featured no upper stage, for lower-mass payloads to higher orbits from Vandenberg.[17]
  • Type 404 featured no upper stage, for heavier payloads to low orbits, from Vandenberg.[17]
  • Type 405 featured no upper stage, for lower-mass payloads to higher-orbit from Cape Canaveral.[17]


Interactive 3D model of the Titan IV, fully assembled (left) and in exploded view (right)

The Titan rocket family was established in October 1955 when the Air Force awarded the Glenn L. Martin Company (later Martin-Marietta, now part of Lockheed Martin) a contract to build an intercontinental ballistic missile (SM-68). The resulting Titan I was the nation's first two-stage ICBM and complemented the Atlas ICBM as the second underground, vertically stored, silo-based ICBM. Both stages of the Titan I used liquid oxygen and RP-1 as propellants.

A subsequent version of the Titan family, the Titan II, was a two-stage evolution of the Titan I, but was much more powerful and used different propellants. Designated as LGM-25C, the Titan II was the largest missile developed for the USAF at that time. The Titan II had newly developed engines which used Aerozine 50 and nitrogen tetroxide as fuel and oxidizer in a self-igniting, hypergolic propellant combination, allowing the Titan II to be stored underground ready to launch. Titan II was the first Titan vehicle to be used as a space launcher.

Development of the space launch only Titan III began in 1964, resulting in the Titan IIIA, eventually followed by the Titan IV-A and IV-B.



By the mid-1980s the United States government worried that the Space Shuttle, designed to launch all American payloads and replace all unmanned rockets, would not be reliable enough for military and classified missions. In 1984 Under Secretary of the Air Force and Director of the National Reconnaissance Office (NRO) Pete Aldridge decided to purchase Complementary Expendable Launch Vehicles (CELV) for ten NRO payloads; the name came from the government's expectation that the rockets would "complement" the shuttle. Later renamed Titan IV,[18] the rocket would only carry three military payloads[19] paired with Centaur stages and fly exclusively from LC-41 at Cape Canaveral. However, the Challenger accident in 1986 caused a renewed dependence on expendable launch systems, with the Titan IV program significantly expanded. At the time of its introduction, the Titan IV was the largest and most capable expendable launch vehicle used by the USAF.[20]

The post-Challenger program added Titan IV versions with the Inertial Upper Stage (IUS) or no upper stages, increased the number of flights, and converted LC-40 at the Cape for Titan IV launches. As of 1991, almost forty total Titan IV launches were scheduled and a new, improved SRM (solid rocket motor) casing using lightweight composite materials was introduced.

Program cost


In 1990, the Titan IV Selected Acquisition Report estimated the total cost for the acquisition of 65 Titan IV vehicles over a period of 16 years to US$18.3 billion (inflation-adjusted US$ 42.7 billion in 2024).[21]

Cassini–Huygens launch


In October 1997, a Titan IV-B rocket launched Cassini–Huygens, a pair of probes sent to Saturn. It was the only use of a Titan IV for a non-Department of Defense launch. Huygens landed on Titan on January 14, 2005. Cassini remained in orbit around Saturn. The Cassini Mission ended on September 15, 2017, when the spacecraft was sent into Saturn's atmosphere to burn up.



While an improvement over the shuttle, the Titan IV was expensive and unreliable.[18] By the 1990s, there were also growing safety concerns over its toxic propellants. The Evolved Expendable Launch Vehicle (EELV) program resulted in the development of the Atlas V, Delta IV, and Delta IV Heavy launch vehicles, which replaced Titan IV and a number of other legacy launch systems. The new EELVs eliminated the use of hypergolic propellants, reduced costs, and were much more versatile than the legacy vehicles.

Surviving examples


In 2014, the National Museum of the United States Air Force in Dayton, Ohio, began a project to restore a Titan IV-B rocket. This effort was successful, with the display opening June 8, 2016.[22] The only other surviving Titan IV components are at the Wings Over the Rockies Air and Space Museum in Denver, Colorado which has two Titan Stage 1 engines, one Titan Stage 2 engine, and the interstage ‘skirt’ on outdoor display;[23] and at the Evergreen Aviation and Space Museum in McMinnville, Oregon, including the core stages and parts of the solid rocket motor assembly.[24]

Launch history

Date /
Time (UTC)
Launch Site S/N Type Payload Outcome Remarks
14 June 1989
CCAFS LC-41 K-1 402A / IUS USA-39 (DSP-14) Success An engine bell burn-through left only a narrow margin for success.
8 June 1990
CCAFS LC-41 K-4 405A USA-60 (NOSS)
USA-59 Satellite Launch Dispenser Communications (SLDCOM)
13 November 1990
CCAFS LC-41 K-6 402A / IUS USA-65 (DSP-15) Success
8 March 1991
VAFB LC-4E K-5 403A USA-69 (Lacrosse) Success
8 November 1991
VAFB LC-4E K-8 403A USA-74 (NOSS)
28 November 1992
VAFB LC-4E K-3 404A USA-86 (KH-11) Success
2 August 1993
VAFB LC-4E K-11 403A NOSS x3
Failure SRM exploded at T+101s due to damage caused during maintenance on ground.
7 February 1994
CCAFS LC-40 K-10 401A / Centaur USA-99 (Milstar-1) Success
3 May 1994
CCAFS LC-41 K-7 401A / Centaur USA-103 (Trumpet) Success
27 August 1994
CCAFS LC-41 K-9 401A / Centaur USA-105 (Mercury) Success
22 December 1994
CCAFS LC-40 K-14 402A / IUS USA-107 (DSP-17) Success
14 May 1995
CCAFS LC-40 K-23 401A / Centaur USA-110 (Orion) Success
10 July 1995
CCAFS LC-41 K-19 401A / Centaur USA-112 (Trumpet) Success
6 November 1995
CCAFS LC-40 K-21 401A / Centaur USA-115 (Milstar-2) Success
5 December 1995
VAFB LC-4E K-15 404A USA-116 (KH-11) Success
24 April 1996
CCAFS LC-41 K-16 401A / Centaur USA-118 (Mercury) Success
12 May 1996
VAFB LC-4E K-22 403A USA-120 (NOSS)
USA-121 (NOSS)
USA-122 (NOSS)
USA-123 Tethers in Space Physics Satellite (TiPS)
USA-124 (TiPS)
3 July 1996
CCAFS LC-40 K-2 405A USA-125 (SDS) Success
20 December 1996
VAFB LC-4E K-13 404A USA-129 (KH-11) Success NROL-2
23 February 1997
CCAFS LC-40 B-24 402B / IUS USA-130 (DSP-18) Success
15 October 1997
CCAFS LC-40 B-33 401B / Centaur Cassini
24 October 1997
VAFB LC-4E A-18 403A USA-133 (Lacrosse) Success NROL-3
8 November 1997
CCAFS LC-41 A-17 401A / Centaur USA-136 (Trumpet) Success NROL-4
9 May 1998
CCAFS LC-40 B-25 401B / Centaur USA-139 (Orion) Success NROL-6
12 August 1998
CCAFS LC-41 A-20 401A / Centaur NROL-7 (Mercury) Failure Guidance system short-circuited at T+40s due to frayed wire, vehicle lost control and destroyed by range safety.
9 April 1999
CCAFS LC-41 B-27 402B / IUS USA-142 (DSP-19) Failure Spacecraft failed to separate from IUS stage.
30 April 1999
CCAFS LC-40 B-32 401B / Centaur USA-143 (Milstar-3) Failure Centaur software database error caused loss of attitude control, insertion burns done incorrectly. Satellite deployed into useless orbit.
22 May 1999
VAFB LC-4E B-12 404B USA-144 (Misty) Success NROL-8
8 May 2000
CCAFS LC-40 B-29 402B / IUS USA-149 (DSP-20) Success
17 August 2000
VAFB LC-4E B-28 403B USA-152 (Lacrosse) Success NROL-11
27 February 2001
CCAFS LC-40 B-41 401B / Centaur USA-157 (Milstar-4) Success
6 August 2001
CCAFS LC-40 B-31 402B / IUS USA-159 (DSP-21) Success
5 October 2001
VAFB LC-4E B-34 404B USA-161 (KH-11) Success NROL-14
16 January 2002
CCAFS LC-40 B-38 401B / Centaur USA-164 (Milstar-5) Success
8 April 2003
CCAFS LC-40 B-35 401B / Centaur USA-169 (Milstar-6) Success
9 September 2003
CCAFS LC-40 B-36 401B / Centaur USA-171 (Orion) Success NROL-19
14 February 2004
CCAFS LC-40 B-39 402B / IUS USA-176 (DSP-22) Success
30 April 2005
CCAFS LC-40 B-30 405B USA-182 (Lacrosse) Success NROL-16
19 October 2005
VAFB LC-4E B-26 404B USA-186 (KH-11) Success NROL-20

Launch failures


The Titan IV experienced four catastrophic launch failures.

1993 booster explosion

Titan IVA K-11 moments before the August 1993 failure

On August 2, 1993, Titan IV K-11 lifted from SLC-4E carrying a NOSS SIGNIT satellite. Unusually for DoD launches, the Air Force invited civilian press to cover the launch, which became more of a story than intended when the booster exploded 101 seconds after liftoff. Investigation found that one of the two SRMs had burned through, resulting in the destruction of the vehicle in a similar manner as the earlier 34D-9 failure. An investigation found that an improper repair job was the cause of the accident.[25]

After Titan 34D-9, extensive measures had been put in place to ensure proper SRM operating condition, including X-raying the motor segments during prelaunch checks. The SRMs that went onto K-11 had originally been shipped to Cape Canaveral, where X-rays revealed anomalies in the solid propellant mixture in one segment. The defective area was removed by a pie-shaped cut in the propellant block. However, most of CSD's qualified personnel had left the program by this point and so the repair crew in question did not know the proper procedure. After replacement, they neglected to seal the area where the cut in the propellant block had been made. Post repair X-rays were enough for CC personnel to disqualify the SRMs from flight, but the SRMs were then shipped to Vandenberg and approved anyway. The result was a near-repeat of 34D-9; a gap was left between the propellant and SRM casing and another burn-through occurred during launch.

1998 IV-A electrical failure


1998 saw the failure of Titan K-17 with a Navy ELINT Mercury (satellite) from Cape Canaveral around 40 seconds into the flight. K-17 was several years old and the last Titan IV-A to be launched. The post-accident investigation showed that the booster had dozens of damaged or chafed wires and should never have been launched in that operating condition, but the Air Force had put extreme pressure on launch crews to meet program deadlines. The Titan's fuselage was filled with numerous sharp metal protrusions that made it nearly impossible to install, adjust, or remove wiring without it getting damaged. Quality control at Lockheed's Denver plant, where Titan vehicles were assembled, was described as "awful".

The proximal cause of the failure was an electrical short that caused a momentary power dropout to the guidance computer at T+39 seconds. After power was restored, the computer sent a spurious pitch down and yaw to the right command. At T+40 seconds, the Titan was traveling at near supersonic speed and could not handle this action without suffering a structural failure. The sudden pitch downward and resulting aerodynamic stress caused one of the SRMs to separate. The ISDS (Inadvertent Separation Destruct System) automatically triggered, rupturing the SRM and taking the rest of the launch vehicle with it. At T+45 seconds, the Range Safety Officer sent the destruct command to ensure any remaining large pieces of the booster were broken up.[26]

An extensive recovery effort was launched, both to diagnose the cause of the accident and recover debris from the classified satellite. All of the debris from the Titan had impacted offshore, between three and five miles downrange, and at least 30% of the booster was recovered from the sea floor. Debris continued to wash ashore for days afterward, and the salvage operation continued until October 15.

The Air Force had pushed for a "launch on demand" program for DOD payloads, something that was almost impossible to pull off especially given the lengthy preparation and processing time needed for a Titan IV launch (at least 60 days). Shortly before retiring in 1994, General Chuck Horner referred to the Titan program as "a nightmare". The 1998-99 schedule had called for four launches in less than 12 months. The first of these was Titan K-25 which successfully orbited an Orion SIGNIT satellite on May 9, 1998. The second was the K-17 failure, and the third was the K-32 failure.

Stage failure to separate


After a delay caused by the investigation of the previous failure, the 9 April 1999 launch of K-32 carried a DSP early warning satellite. The IUS second stage failed to separate, leaving the payload in a useless orbit. Investigation into this failure found that wiring harnesses in the IUS had been wrapped too tightly with electrical tape so that a plug failed to disconnect properly and prevented the two IUS stages from separating.

Programming error


The fourth launch was K-26 on April 30, 1999, carrying a Milstar communications satellite. During the Centaur coast phase flight, the roll control thrusters fired open-loop until the RCS fuel was depleted, causing the upper stage and payload to rotate rapidly. On restart, the Centaur cartwheeled out of control and left its payload in a useless orbit. This failure was found to be the result of an incorrectly programmed equation in the guidance computer. The error caused the roll rate gyro data to be ignored by the flight computer.[27]

See also



  1. ^ a b "Lockheed Martin's Last Titan IV Successfully Delivers National Security Payload to Space". October 19, 2005. Archived from the original on January 14, 2008.
  2. ^ "USRM". www.astronautix.com. Archived from the original on December 27, 2016.
  3. ^ "Analysis of Titan IV Launch Responsiveness" (PDF). Analysis of Titan IV Launch Responsiveness (pg. 28). Retrieved February 26, 2024.
  4. ^ "Space and Missile System Center Mission and Organization" (PDF). Space and Missile Systems Center's History Office. Archived from the original (PDF) on September 11, 2008. Retrieved September 20, 2008.
  5. ^ "Titan 4B and Cape Canaveral". Space.com. Archived from the original on 2001-10-31. Retrieved 2008-05-21.
  6. ^ "Spaceflight Now | Titan Launch Report | Titan 4 rocket expected to launch Lacrosse spy satellite". spaceflightnow.com.
  7. ^ Nemiroff, R.; Bonnell, J., eds. (27 October 2005). "The Last Titan". Astronomy Picture of the Day. NASA. Retrieved 2008-09-20.
  8. ^ Backlund, S. J.; Rossen, J. N. (December 1971). A STUDY OF PERFORMANCE AND COST IMPROVEMENT POTENTIAL OF THE 120-IN.- (3.05 M) DIAMETER SOLID ROCKET MOTOR (PDF) (Report). United Aircraft Corporation. Retrieved 26 February 2016.
  9. ^ Study of Solid Rocket Motors for a Space Shuttle Booster (PDF) (Report). United Technology Center. 15 March 1972. Retrieved 26 February 2016.
  10. ^ "UA1207". Astronautix. Archived from the original on 4 March 2016. Retrieved 26 February 2016.
  11. ^ "Titan 4B". www.astronautix.com. Archived from the original on December 27, 2016.
  12. ^ Michael Timothy Dunn (Dec 1992). "Analysis of Titan IV launch responsiveness" (PDF). Air Force Institute of Technology. Archived (PDF) from the original on October 9, 2012. Retrieved 2011-07-08.
  13. ^ States, Air Force, United (26 February 1990). "TITAN IV - SOLID ROCKET MOTOR UPGRADE PROGRAM AT VANDENBURG". ceqanet.opr.ca.gov.{{cite web}}: CS1 maint: multiple names: authors list (link)
  14. ^ Chalhoub, Michel S., (1990) "Dynamic Analysis, Design, and Execution of a Full Scale SRMU Test Stand," Parsons Engineering Report No. 027-90
  15. ^ "Early Lunar Access". www.astronautix.com. Archived from the original on August 20, 2016.
  16. ^ "Super Lightweight External Tank" (PDF). NASA.gov. Retrieved November 3, 2022.
  17. ^ a b c "Encyclopedia Astronautica Index: T". www.astronautix.com. Archived from the original on July 10, 2016.
  18. ^ a b Day, Dwayne A. "The spooks and the turkey" The Space Review, 20 November 2006.
  19. ^ Eleazer, Wayne (2020-07-06). "National spaceports: the past". The Space Review. Retrieved 2020-07-07.
  20. ^ "Titan IV". USAF Air University. 1996.
  21. ^ Kingsbury, Nancy R. (September 1991). "TITAN IV LAUNCH VEHICLE --- Restructured Program Could Reduce Fiscal Year 1992 Funding Needs" (PDF). US General Accounting Office.
  22. ^ "National Museum of the U.S. Air Force fourth building now open". National Museum of the United States Air Force™. 7 June 2016.
  23. ^ "Titan Missile Program". Wings over the Rockies Museum.
  24. ^ "Titan IV Solid Rocket Motors Destroyed". www.spacearchive.info.
  25. ^ "Titan 403A". www.astronautix.com. Archived from the original on December 28, 2016.
  26. ^ "Titan Centaur 401A". www.astronautix.com. Archived from the original on 3 March 2016.
  27. ^ Leveson, Nancy G., Ph.D. (September 10–14, 2001). "The Role of Software in Recent Aerospace Accidents" (PDF). sunnyday.mit.edu. 19th International System Safety Conference. Retrieved 19 April 2020.{{cite web}}: CS1 maint: multiple names: authors list (link)
  • USAF Titan IVB Fact Sheet Archived 2018-04-30 at the Wayback Machine
  • Titan IV Ignition Videos
  • Cassini Huygens Aboard a Titan IV-B Launch Videos
  • Early Lunar Access