Cryogenic liquid storage system for a spacecraft

A cryogenic liquid storage system for a spacecraft, the system comprising:

• at least one liquid tank having a diameter;
• an outermost spherical casing surrounding the tank;
• an evacuated space provided between the tank and the outermost casing;
• a propellant management device made of material that is a good conductor of heat and that is cooled by a cryorefrigerator to localize the liquid inside the tank when in microgravity;
• a filler pipe situated in the portion of the tank that is at the bottom when the tank is on the ground, and that is surrounded by an evacuated insulating double wall;
• and
• a purge pipe connecting the tank to the outermost casing and presenting an internal length that is not less than half the diameter of the tank;
• and
• means for holding the tank inside the outermost casing, the holding means being directly in contact with both the outermost casing and the tank and presenting a low thermal conductivity and being spaced apart angularly by 30° to 120° relative to the propellant management device that is cooled by the cryorefrigerator,
• wherein said system includes super-insulating material interposed between the tank and the outermost casing,
• wherein said holding means comprise a fastener frustoconical skirt of insulating material interposed in the vicinity of an equatorial plane between the tank and the outermost casing,
• wherein said system includes an evaporator immersed in the liquid of the tank at the location closest to the cryorefrigerator, which the evaporator comprises a porous material and is extended by a tube of small section that is connected to the outermost casing;
• and
• wherein a heater element is associated with the evaporator and is located at an outlet of the tube of small section and at the skirt or outermost spherical casing.