Émeraude VE121 (French for "emerald") was a large French
sounding rocket
A sounding rocket or rocketsonde, sometimes called a research rocket or a suborbital rocket, is an instrument-carrying rocket designed to take measurements and perform scientific experiments during its sub-orbital flight. The rockets are used to ...
of the 1960s. It built on the experiences of the
Véronique and Vesta programs, and though it was only used for one year, it tested important technologies that were used in later French launch vehicles, from the
Topaze and
Saphir sounding rockets to the
Diamant
The Diamant rocket (French for "diamond") was the first exclusively French expendable launch system and at the same time the first satellite launcher not built by either the United States or USSR. As such, it has been referred to as being a ke ...
, the multi-stage orbital rocket that was used to launch France's first satellite, the
Asterix-1. Emeraude was launched exclusively from the
Centre interarmées d'essais d'engins spéciaux
The Interarmy Special Vehicles Test Centre (CIEES) (French: Centre Interarmées d'Essais d'Engins Spéciaux) was France's first space launch and ballistic missile testing facility. Outside France, the facility is often referred to by the name of ...
(CIEES) launch site in
Hammaguir
Hammaguir (also written Hamaguir and Hammaguira) ( ar, حماقير) is a village in Abadla District, Béchar Province, Algeria, south-west of Béchar. It lies on the N50 national highway between Béchar and Tindouf. The location is notable for ...
,
Algeria
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.
Its codename, VE121, means Vehicle Experimental; 1 stage, liquid propellant (code 2), guided (code 1).
The rocket was liquid-fueled and carried 12.8 tonnes of fuel and oxidizer—nitric acid and gasoline turpentine—which were pressure-fed into the four Vexin-B engines, providing a total of 301.55
kN of thrust.
[
] Pitch and yaw control were provided by gimbaling the four engines while roll control was provided by aerodynamic fins. The rocket could carry a payload to an altitude of 200 km.
Emeraude was considered part of the "''pierres précieuses''" ("precious stones") rocket family, the family of sounding rockets that led up to the Diamant orbital rocket. The first launches of Emeraude – on June 15, June 17, and October 20, 1964 – were failures, casting doubt on the entire ''pierres précieuses'' program. These three launches had failed because of propellant sloshing due to
pogo oscillation
Pogo oscillation is a self-excited vibration in liquid-propellant rocket engines caused by combustion instability. The unstable combustion results in variations of engine thrust, causing variations of acceleration on the vehicle's flexible struct ...
, a problem that was fixed before the fourth launch.
However, the final two launches – on February 27 and May 13, 1965 – went well, with the latter flight reaching an altitude of 180 km. The final test carried a
dummy Topaze stage for testing the aerodynamics of Emeraude's successor, the Saphir.
References
{{Reflist
Space launch vehicles of France
Sounding rockets of France