Cryogenic propellant depot and integral sunshield

Abstract

A cryogenic propellant depot and sunshield are provided for operation in earth orbit to fuel or refuel other space vehicles. The sunshield is deployed to effectively mitigate solar radiation emanating from the earth and the sun thereby providing a long term storage solution for cryogenic fluids prone to boil-off. The depot has supporting subsystems to include station keeping equipment and communication equipment so that the depot can be independently controlled. Inflatable booms are used to deploy the sunshield in a desired pattern around the depot.

1 . In combination, a cryogenic propellant depot incorporating an integral sunshield, said combination comprising:
 a tank having a sidewall enclosing a quantity of cryogenic liquid therein;   a bulkhead attached to an end of said tank, said bulkhead having an interior open space defining a thermal isolation reservoir between the tank and the bulkhead;   a docking port formed on said bulkhead and communicating with an interior of said tank for selectively evacuating liquid in said tank; and   a sunshield attached to said tank, said sunshield having a first smaller end secured adjacent said docking port, and a second larger end extending away from said first end and having a length that exceeds a length of said tank, said sunshield forming a truncated cone shape to cover said tank when viewing said tank from a side view.   
     
     
         2 . The combination, as claimed in  claim 1 , wherein:
 said tank has a longitudinal axis, and said sunshield extends symmetrically with respect to said longitudinal axis in the truncated cone shape.   
     
     
         3 . The combination, as claimed in  claim 1 , wherein:
 said tank rotates about its longitudinal axis such that a gas core is formed extending through a center of the tank and along said longitudinal axis.   
     
     
         4 . The combination, as claimed in  claim 1 , wherein:
 said tank is maintained at a first pressure, and said thermal isolation reservoir is maintained at a second lower pressure.   
     
     
         5 . The combination, as claimed in  claim 1 , wherein:
 said thermal isolation reservoir includes gas dispersed therein, said gas being provided from a gas annulus from said tank.   
     
     
         6 . The combination, as claimed in  claim 1 , wherein:
 said sunshield includes a plurality of layers of materials secured to one another.   
     
     
         7 . A method of providing solar radiation shielding for space vehicles comprising:
 providing a sunshield secured to said space vehicle, said space vehicle having a longitudinal axis, and said sunshield being deployed symmetrically along said longitudinal axis forming a substantially truncated cone shape surrounding said space vehicle.   
     
     
         8 . In combination, an upper stage of a launch vehicle including an integral sunshield, said combination comprising:
 an upper stage of the launch vehicle including a tank having a sidewall enclosing a quantity of cryogen liquid therein;   a propulsion system incorporated with said upper stage including at least one rocket engine for propelling said upper stage;   a bulkhead attached to an end of said tank, said bulkhead having an interior open space defining a thermal isolation reservoir between the tank and the bulkhead;   a docking port formed on said bulkhead and communicating with an interior of said tank for selectively evacuating liquid in said tank; and   a sunshield attached to said tank, said sunshield forming a truncated cone shape around said upper stage and extending beyond a length of said upper stage wherein said tank extends along a longitudinal axis, and said sunshield is deployed symmetrically along said longitudinal axis in said truncated cone shape.   
     
     
         9 . The combination, as claimed in  claim 8 , wherein:
 said sunshield covers said tank when viewing said tank at a direction orthogonal to said longitudinal axis.   
     
     
         10 . The combination, as claimed in  claim 8 , further including:
 a payload secured to said docking port.   
     
     
         11 . In sub-combination, a cryogenic storage tank comprising:
 a tank having a sidewall enclosing a quantity of cryogen liquid therein;   a bulkhead attached to an end of said tank, said bulkhead having an interior open space defining a thermal isolation reservoir between the tank and the bulkhead;   a docking port formed adjacent said bulkhead and communicating with an interior of said tank for selectively evacuating liquid in said tank.   
     
     
         12 . The sub-combination, as claimed in  claim 11 , further including: an equipment deck attached to said bulkhead via a low conductivity truss structure; 
     
     
         13 . A method of maintaining a liquid cryogen in space for transfer to a space vehicle comprising:
 providing a tank containing a quantity of liquid cryogen therein spinning the tank about its longitudinal axis to create a gas core for gas in the tank that has boiled; and   removing liquid from the tank without interference from the gas core and transferring the liquid to the space vehicle docked with the tank.   
     
     
         14 . The method, as claimed in  claim 13 , further comprising:
 providing a bulkhead secured to the tank and the bulkhead defining a thermal isolation chamber;   venting gas from the tank into the chamber;   maintaining the gas in the chamber at a pressure less than a pressure in the tank; and   using the gas in the chamber to facilitate transfer of liquid from the tank.