SyLEx suborbital rocket test at Biscarrosse for France’s M51.4 nuclear missile program, Digi Mart USA News (Biscarrosse, Landes, France): The French Defense Procurement Agency (DGA) launched the SyLEx sounding rocket from Biscarrosse in the Landes region during the night of November 3 to 4, 2026, according to Armed Forces Minister Catherine Vautrin. The launch aimed to test technologies for the future M51.4 nuclear missile.
This was the second flight of SyLEx, following a first successful test during the night of November 27 to 28, 2025. The launch was conducted from the Landes site of the DGA Missile Testing Center.
The first flight carried an experimental payload for the Ministry of the Armed Forces.
In a November 4 post on X, Vautrin wrote: “This national launcher allows new technologies to be tested in flight for the benefit of French deterrence, the development of hypersonic demonstrators and civil applications.”
The minister linked this flight to acceptance test No. 6, carried out less than a month earlier from the nuclear ballistic missile submarine Le Vigilant. That October 6, 2026 test involved an unarmed M51.3 missile.
The new experiments with SyLEx are being used to develop the M51.4.
The DGA entrusted the program to ArianeGroup on August 28, 2025. The M51.4, the fourth version of the M51 ballistic missile, is expected to enter service in the 2030s on Triomphant-class submarines and later on third-generation submarines.
According to the DGA, as cited by AeroTime, it will offer greater range, more precision and an improved ability to penetrate adversary missile defenses.
The flight mainly supports development of the payload, the section of the missile that carries the nuclear warheads.
SyLEx (Experimental Launch System) was developed by ArianeGroup under DGA direction in less than three years. It includes two sounding rockets, a single-stage and a two-stage version, and a dedicated launch base.
A sounding rocket makes a round trip to altitude without reaching orbit.
For certain high-atmosphere tests, France previously had to rely on foreign facilities. On June 26, 2023, the V-MAX hypersonic glider was tested from Biscarrosse using a three-stage sounding rocket launched by the U.S.
Navy.
Vautrin said SyLEx restores a capability France had lost: “Even more, it gives France a sovereign capability for suborbital flights and high-atmosphere testing, which it had been deprived of for several decades.”
Vincent Péry, director of defense programs at ArianeGroup, said: “We are continuing in parallel to work with the DGA on the next step of our incremental roadmap.” The two-stage version, capable of carrying 600 kg, has not yet flown; ArianeGroup plans its first flight by 2027.
