Monge (A601), named after the 18th century mathematician Gaspard Monge, is a unique missile range instrumentation ship of the French Navy dedicated to tracking and measuring rocket trajectories. She was built for the trials of the submarine-launched ballistic missiles of the French Navy, and is also used to monitor the launch of Ariane rockets. The ship was built by Chantiers de l'Atlantique, Saint-Nazaire and was launched on 6 October 1990. The vessel entered service on 5 November 1992 and is based at Brest, France. Description Monge is a unique missile range instrumentation ship of the French Navy. The vessel has a standard displacement of and at full load. The ship measures long overall with a beam of and a draught of . Monge is powered by two SEMT Pielstick 8PC 2.5 L400 diesel engines driving one shaft turning a controllable-pitch propeller, rated at . The vessel is also equipped with one bow thruster. The ship has a maximum speed of and a range of at . The missile range instrumentation ship mounts two 20 mm modèle F2 guns and two machine guns. Monge has a landing platform and a hangar. The ship can operate heavy helicopters. Monge is equipped with one Aérospatiale Alouette III helicopter. The vessel has a complement of 115 naval personnel plus 90 military and civilian technicians. Radar systems The systems in Monge allow the vessel to track missiles and satellites. There are two navigational radars operating on the I-band, one for control of the helicopters, and a Thomson-CSF DRBV 15C air surveillance radar operating on the E and F-bands installed. The intelligence systems are a Stratus radar operating on the L-band for trajectory tracking, a Gascogne, two Armor, and one Savoie radars for missile tracking operating on the C-band. Furthermore, there are six Antares telemetry-tracking radars operating on the E and F-bands, a laser-radar, and an optical tracking unit, and 14 antennas for telemetry. In 2009, the Stratus and Savoie radars were replaced by a Normandie radar for the trials of the M51 missile. Service history The ship was ordered on 25 November 1988 as a replacement for the aging . The ship's keel was laid down on 26 March 1990 with the yard number H39 by Chantiers de l'Atlantique at their yard in Saint-Nazaire, France. Monge, named for the 18th century mathematician Gaspard Monge, was launched on 6 October 1990. Monge entered service with the