This monograph recounts and details the development of a nuclear rocket engine reactor (NRER). In particular, it explains the working capacity of an active zone NRER under mechanical and thermal load, intensive neutron fluxes, and high-energy generation (up to 30 MBT/l) in a working medium (hydrogen) at temperatures up to 3100 K. The design principles and bearing capacity of reactors area discussed on the basis of simulation experiments and test data of a prototype reactor. Property data of dense constructional, porous thermal insulating and fuel materials such as carbide and uranium carbide compounds in the temperatures interval 300 - 3000 ... Read moreK are presented.; technological aspects of strength and thermal strength resistance of materials are also considered. As well, a procedure to design possible emergency processes in the NRER is developed and risks for their origination are evaluated. Finally, prospects for use in pilotless space devices and piloted interplanetary ships are reviewed.