Missile M51

The M51 submarine-launched ballistic missile was developed to replace the previous M45 system. Its design origins trace back to the M5 program of the late 1980s, which was officially renamed the M51 in 1996 following a restructuring that reduced development costs. The missile's three-stage solid propellant engine is directly derived from the boosters used on the Ariane 5 space launch vehicle. After a series of flight tests, the M51 officially entered service with the French Navy in 2010.

Powered by a three-stage solid-fuel rocket, the M51 is a long-range strategic missile capable of reaching hypersonic speeds of up to Mach 25. While its exact operational range is classified, it is estimated to be between 8,000 and 10,000 kilometers. The missile uses an astro-inertial guidance system, with plans to integrate the Galileo satellite navigation system in the future. It is equipped with an extensible aerospike to improve its aerodynamic performance. The M51.1 variant can carry between six and ten independently targetable (MIRV) TN 75 thermonuclear warheads, which are accompanied by penetration aids to overcome defenses. A subsequent M51.2 variant, introduced in 2015, carries the new Tête nucléaire océanique warhead. An M51.3 upgrade is currently under development and is planned for service around 2025.

The M51 serves as the primary strategic armament for the French Navy's Triomphant-class ballistic missile submarines (SSBNs) and is planned for integration into the future SNLE 3G class. Its entry into service was preceded by a thorough test campaign that began in 2006. A key milestone occurred in January 2010 with the first successful underwater launch from the submarine Le Terrible. A later test in July 2010 formally validated the capacity of the Triomphant-class submarines to operate the missile. The system's readiness and reliability have since been maintained through regular test firings, conducted from both submerged submarines and land-based facilities. While one test in 2013 failed, the program has maintained a high rate of success through numerous launches, including tests of upgraded missile variants.