SPACE NUCLEAR SYSTEMS
Nuclear power sources have enabled or enhanced some of the most challenging and exciting space missions ever conducted. Since 1961, 48 radioisotope thermo-electric generators and 36 space nuclear reactors were successfully flown to provide power for 62 space systems. Yet, the future of nuclear technology for space exploration promises even more remarkable journeys and more amazing discoveries.
Space fission nuclear systems can be divided in radioisotope power generators, nuclear thermal propulsion, nuclear electric propulsion and fission surface power technologies. Space radioisotope power systems use radioisotope decay to generate heat and electricity for space missions. For the last fifty-four years, radioisotope thermo-electric generators (RTGs) have provided safe, reliable electric power for space missions where solar power is not feasible. The new advanced sterling radioisotope generators (ASRGs) are sought to do an even more efficient job on heat and electricity generation for future space missions. But future space missions will need increased power for propulsion and for surface power applications to support both robotic and human space exploration missions. Nuclear thermal propulsion (NTP) and nuclear electric propulsion (NEP) are the most technically mature, advanced propulsion systems that can enable a rapid access to different regions of interest throughout the solar system. The latter is possible by its ability to provide a step increase above what is feasible using a traditional chemical rocket system. Nuclear fission-based power systems are the best suited power sources for surface missions requiring high power in difficult environments where sunlight is limited and reliability is paramount.
We aim to develop R&D and design engineering activities in space nuclear systems and associated technologies as well as project management and research commercialization through spin-offs and joint-ventures.
While in chemical rockets hot gases are created by chemical combustion, in nuclear thermal rockets the hot gas is created by heating the propellant in a nuclear fission reactor. Bimodal versions run electrical systems on board a spacecraft, including radars, as well as provide propulsion.
In order to meet the large power needs for some future missions, solar or radioisotope power systems may be impractical. Nuclear fission reactors are the only reliable power source where sunlight is limited. These are small reactors with a minimum requirement of 3kWe and an average of a 30 - 40 kWe system with 8 or 9 years design life suitable mainly for lunar and Mars surface applications.
Radioisotope thermoelectric generators (RTGs) are devices that transform the heat produced by a radioactive source into electricity. This is done by the use of an array of thermocouples through Seebeck effect, which is the conversion of temperature differences directly into electricity. RTGs are also used to provide heat for the scientific and technical instruments to operate under the low temperatures found in space.
In nuclear electric systems, nuclear reactors are a heat source for electric ion drives expelling plasma out of a nozzle to propel spacecraft already in space. Magnetic cells ionize hydrogen or xenon, heat it to extremely high temperatures, accelerate it and expel it at very high velocity to provide thrust. NEP propulsion is a combination of magnetoplasmadynamics and nuclear power systems. Nuclear power systems are the only alternative for any thruster that consumes more than 100 kW of power.