The Titan IV Solid Rocket Motor Upgrade (SRMU) was developed by Alliant Aerospace Company for the U.S. Air Force to increase the launch capability of the Titan IVB.  The SRMU provides 25% more performance than its predecessor and enables the Titan IVB to loft heavier payloads. The first SRMU-equipped Titan IVB was launched in February 1997.  The second flight in 1997 launched the Cassini Spacecraft and the Huygens Probe on a mission to study Saturn's moons, rings, and environment for four years.

Alliant developed the SRMU during 1992-93 time period.  The rocket cases are filament wound using a composite of high-strength IM7 fiber and durable HBRF-55B epoxy resin.  The SRMU is a three-segment, 10.5 ft diameter solid rocket motor.  In the Titan IVB flight sequence, the two SRMUs are ignited on the pad and provide primary propulsion from liftoff to approximately 70,000 feet.