Launch of the last CT-3 with Mars Observer
Function	Medium carrier rocket
Manufacturer	Martin Marietta
Country of origin	United States
Size
Height	47.3 m
Width	9.2 m
Mass	680,000 kg
Stages	UA1206 (2) Titan 3B-1 Titan 3B-2
Associated rockets
Family	Titan
Launch history
Status	Retired
Launch sites	LC-40, CCAFS
Total launches	4
Success(es)	3
Partial failure(s)	1
First flight	1 January 1990
Last flight	25 September 1992
Type of passengers/cargo	Mars Observer
[edit on Wikidata]

The Commercial Titan III, also known as CT-3 or CT-III, was an American expendable launch system, developed by Martin Marietta during the late 1980s and flown four times during the early 1990s. It was derived from the Titan 34D, and was originally proposed as a medium-lift expendable launch system for the US Air Force, who selected the Delta II instead. Development was continued as a commercial launch system, and the first rocket flew in 1990. Due to higher costs than contemporary rockets such as the Ariane 4, orders were not forthcoming, and the CT-3 was retired in 1992.^{[citation needed]}

The Commercial Titan III differed from the Titan 34D in that it had a stretched second stage, and a larger payload fairing to accommodate dual satellite payloads.

All four launches occurred from LC-40 at Cape Canaveral Air Force Station. The first carried two communications satellites, Skynet 4A and JCSAT-2, and was launched at 00:07 UTC on 1 January 1990, which was 19:07 local time on 31 December 1989, making it the only orbital launch to have occurred in different years between the launch site and UTC.^{[citation needed]} The launch received the International Designator 1990-001, using the UTC date.

The second launch occurred on 14 March, and carried the Intelsat 603 satellite. The rocket's second stage failed to separate, and the payload could only be released from the rocket by means of jettisoning its kick motor. It was later visited by Space Shuttle Endeavour, on mission STS-49. Astronauts attached a new kick motor, which raised the satellite into a geosynchronous transfer orbit, as had originally been planned.

The third launch, on 23 June, carried Intelsat 604, and was successful. There was no Commercial Titan III launch in 1991, due to maintenance work at Launch Complex 40.^{[citation needed]}

The final flight of the Commercial Titan III occurred on 25 September 1992, and placed NASA's Mars Observer spacecraft into heliocentric orbit, by means of a Transfer Orbit Stage.^{[citation needed]}

Launch history