Titan IIIE

Titan IIIE

Launch of a Titan IIIE with Voyager 2
Function	Expendable launch system
Manufacturer	Martin Marietta
Country of origin	USA
Size
Height	48 m (157 ft)
Diameter	3.05 m (10.0 ft)
Mass	632,970 kg (1,395,460 lb)
Stages	3-4
Capacity
Payload to LEO	15,400 kg (34,000 lb)
Payload to Heliocentric orbit (TMI)	3,700 kg (8,200 lb)
Associated rockets
Family	Titan
Launch history
Status	Retired
Launch sites	LC-41, Cape Canaveral
Total launches	7
Successes	6
Failures	1
First flight	11 February 1974
Last flight	5 September 1977
Notable payloads	Voyager (1 / 2) Viking (1 / 2) Helios
Boosters (Stage 0)
No. boosters	2
Motor	UA1205
Thrust	5,849 kN (1,315,000 lbf)
Specific impulse	263 sec
Burn time	115 seconds
Fuel	Solid (Polybutadiene acrylonitrile)
First stage
Engines	2 LR87-11
Thrust	2,340 kN (530,000 lbf)
Specific impulse	302 sec
Burn time	147 seconds
Fuel	A-50/N2O4
Second stage
Engines	1 LR91-11
Thrust	454 kN (102,000 lbf)
Specific impulse	316 sec
Burn time	205 seconds
Fuel	A-50/N2O4
Third stage - Centaur-D
Engines	2 RL-10A-3
Thrust	131 kN (29,000 lbf)
Specific impulse	444 sec
Burn time	470 seconds
Fuel	LH2/LOX
Fourth stage (optional) - Star-37E
Engines	1 solid
Thrust	68 kN (15,000 lbf)
Specific impulse	284 sec
Burn time	42 seconds
Fuel	Solid

The Titan IIIE or Titan 3E, also known as Titan III-Centaur was an American expendable launch system. Launched seven times between 1974 and 1977,^[1] it enabled several high-profile NASA missions, including the Voyager and Viking planetary probes, and the joint West German-US Helios spacecraft. All seven launches were conducted from Launch Complex 41 at Cape Canaveral.

Development

In 1967, NASA began considering the possibility of combining the massive Titan III booster and Centaur high-energy upper stage to create what was at the time the most powerful launch vehicle for planetary exploration. With over three times the payload capacity of the Atlas-Centaur, Titan IIIE would be able to launch ambitious robotic spacecraft missions planned for the 1970s.

NASA's Lewis Research Center (now the Glenn Research Center) was given the task of integrating Titan with Centaur, which required a number of modifications to accommodate the more powerful booster. The most obvious change was enclosing Centaur in a large shroud that protected the stage and the payload during ascent. This enabled the use of improved insulation on Centaur, which increased coast time in orbit from 30 minutes when launched on Atlas to over 5 hours on the Titan IIIE. Since Centaur was wider than the Titan's core stage, a tapering interface was required. This interface had to be insulated to prevent boiloff of Centaur's cryogenic propellants, since Titan used hypergolic propellants stored at ambient temperature, while Atlas used liquid oxygen. The Centaur stage also contained the guidance computer for the entire launch vehicle.

A four-stage configuration, with an additional upper stage, a Star-37E, was also available, and was used for the two Helios launches.^[2] Star-37E stages were also used on the two Voyager launches, but were considered to be part of the payload rather than the rocket.^[3]

Flights

The first Titan IIIE launch occurred on February 11, 1974. Original plans were to fly a boilerplate Viking probe, but NASA decided to add a secondary payload: a test satellite called SPHINX (Space Plasma High Voltage Interaction Experiment) which was intended to test the operation of high voltage power supplies in the vacuum of space. The Titan performed normally, but the Centaur's engines failed to start. Ground controllers waited for a minute, then issued a manual start command but still nothing happened. With the Centaur descending back towards Earth, the range safety destruct command was sent from a radar station in Antigua.

The failure was traced to the Centaur boost pumps, but the cause was still unclear, thought likely to be either ice or debris. To reduce the chance of another similar failure, pre-launch procedures to verify Centaur's pumps were free and unobstructed were put in place. It took nearly four years to trace the cause of the failure, which was an improperly-installed mounting bracket inside the LOX tank. This bracket held a LOX regulator in place and the technician responsible for installing it had found that the normal tool used to screw bolts into place was too short to reach the bracket. He thus used a slightly longer socket wrench which gave him more reach. The technician had since retired and failed to inform his successor about this. The new technician thus attempted to attach the bolt with the wrench specified in the assembly instructions, which was too short and prevented him from screwing it into place properly. The bolt came loose, fell off, and got sucked into one of the LOX boost pumps, jamming it and preventing it from operating.^[4] Despite the failure, at least one important goal was accomplished in that the bulging Centaur payload shroud was proven to be aerodynamically stable in flight and had jettisoned properly and on schedule.

The next flight of the Titan IIIE was on December 10, 1974, carrying the Helios-A spacecraft. This mission was successful, as were all subsequent launches.

Launch History

Date/Time (GMT)	S/N		Payload	Outcome	Remarks
	Titan	Centaur
11 February 1974 13:48:02	23E-1	TC-1	Sphinx	Failure	Centaur LOX turbopump malfunction. RSO destruct at T+742 seconds.
10 December 1974 07:11:02	23E-2	TC-2	Helios-A	Successful	First space probe to orbit closer to the Sun than Mercury.
20 August 1975 21:22:00	23E-4	TC-4	Viking 1	Successful	Carried a lander that landed on Mars.
9 September 1975 18:39:00	23E-3	TC-3	Viking 2	Successful	Carried a lander that landed on Mars.
15 January 1976 05:34:00	23E-5	TC-5	Helios-B	Successful	Holds the record for fastest velocity relative to the Sun achieved by a space probe.
20 August 1977 14:29:44	23E-7	TC-7	Voyager 2	Successful	Additionally boosted by a Star 37E upper stage. Flew by Jupiter, Saturn, Uranus and Neptune, completing the Planetary Grand Tour. Now leaving the Solar System.
5 September 1977 12:56:01	23E-6	TC-6	Voyager 1	Successful	Additionally boosted by a Star 37E upper stage. Flew by Jupiter and Saturn. Exited the Solar System heliosphere in 2012. Currently the most distant man-made object from Earth.

Design

Schematics of Titan IIIE with two solid rocket motors (Stage 0) and the Titan III core vehicle Stages I and II

References

1. Wade, Mark. "Titan". Encyclopedia Astronautica. Retrieved 2009-01-25.
2. Krebs, Gunter. "Titan-3E Centaur-D1T Star-37E". Gunter's Space Page. Retrieved 2009-01-25.
3. Krebs, Gunter. "Titan-3E Centaur-D1T". Gunter's Space Page. Retrieved 2009-01-25.
4. Dawson, Virginia; Bowles, Mark (2004). Taming Liquid Hydrogen: The Centaur Upper Stage Rocket 1958-2002 (PDF). NASA. pp. 145–146.

External links

Media related to Titan IIIE at Wikimedia Commons