page_title: 6555th Aerospace Test Group
section_title: Titan IV (1988–1990)
hierarchical_section_title: 6555th Aerospace Test Group / History / Space launch operations / Titan IV (1988–1990)
caption_attribution_description: English: First TITAN IV launch from Complex 41 - 14 June 1989
context_page_description: The 6555th Aerospace Test Group is an inactive United States Air Force unit. It was last assigned to the Eastern Space and Missile Center and stationed at Patrick AFB, Florida. It was inactivated on 1 October 1990.
  Prior to the activation of the Air Force Space Command, the unit was responsible for the development of USAF missiles, both tactical surface-to-surface; CIM-10 Bomarc Interceptor; SM-62 Snark Intercontinental Cruise Missile; Intercontinental ballistic missile and heavy launch rockets used for military for satellite deployment. The unit played a key role in the civilian NASA Project Mercury, Project Gemini and Project Apollo manned space programs along with military Space Shuttle flights.
  The mission of the unit today is performed by the 45th Space Wing.
context_section_description: As TITAN 34D launch operations continued, the first Titan IV liquid rocket engines were installed on the Titan IV "pathfinder" vehicle at the end of January 1988, shortly before the core vehicle was erected in the VIB. Four Titan IV solid rocket motor segments were received at the SMAB by the middle of February 1988, and two electrical functional tests were conducted in early March. As "bugs" were worked out of various systems, the core vehicle had its first successful CST on 11 May 1988. The vehicle was moved to the SMAB around the middle of May. Following a successful mate with two five-segment stacks of solid rocket motor segments, the pathfinder vehicle was moved out to Complex 41 on Saturday, 21 May.  The first Titan IV vehicle supported a classified mission. Its launch had been scheduled for 7 June 1989, but the lift-off was pushed to 14 June due to a range timing generator problem and a computer malfunction. The countdown was picked up at 0254Z on 14 June. Two unscheduled holds were called to let the launch team catch up on checklist items that were behind schedule, and another hold was called for a high temperature reading on the vehicle's S-Band transmitter. Following the last unscheduled hold, the countdown proceeded uneventfully, and the Titan IV lifted off Complex 41 at 1318:01Z on 14 June 1989.
caption: First Titan IV Launch from LC 41, 14 June 1989
exif: {}