Patent Number: 
Section: claims

1. A modular nuclear reactor for space propulsion of a spacecraft comprising:(a) a nuclear reactor module having a top-end and a bottom-end, which consists of a reactor and a high enriched uranium core, the reactor converts nuclear energy to thermal energy, wherein the nuclear reactor module is cone-shaped and designed in a concentric geometry with a common center, including locking mechanisms and all interconnecting utilities and transfer-lines such that it can be coupled with another module, in low earth orbit;(b) a propulsion propellant module that contains a gas being one of helium or hydrogen, the propulsion propellant module is cone-shaped and designed in a concentric geometry with a common center, including locking mechanisms and all interconnecting utilities and transfer-lines such that it can be coupled with another module, in low earth orbit; wherein the thermal energy from the reactor is designed to be transferred to the propulsion propellant module's gas as it passes through the reactor, the gas becoming superheated and expending through a nozzle creating thrust for the spacecraft, wherein the nozzle is designed at the bottom-end of the nuclear reactor module, and wherein the spacecraft includes(c) instrumentation, supplies, equipment, electric power, and crew modules also cone-shaped and designed in a concentric geometry with a common center, including locking mechanisms and all interconnecting utilities and transfer-lines such that it can be coupled with another module, in low earth orbit; wherein(d) the propulsion propellant module is designed to provide radiation shielding, and further designed to couple with the top-end of the nuclear reactor module first; the instrumentation, supplies, equipment, electric power, and crew modules are designed to couple with the propulsion propellant module in the specified sequence; and wherein(e) the assembly of the spacecraft is designed to take place in low earth orbit. 2. The modular nuclear reactor for space propulsion of a spacecraft of claim 1 wherein all modules, either individually or in combination, are designed to be carried into low earth orbit by conventional chemical rockets.