Gizmag reports that a team at NASA has embarked on a project called the Nuclear Cryogenic Propulsion Stage (NCPS) designed to be the upper stage of launch vehicles and the primary propulsion for deep space craft.
Nuclear thermal rockets
The NCPS is envisioned to be a nuclear thermal rocket. Princeton University defines such an engine as using a nuclear reactor to heat a fluid, which is then expanded through a rocket nozzle to create thrust. The advantage of such an engine over a conventional chemical engine is that propellant efficiency of a nuclear engine is at least twice as much as a chemical engine, creating higher thrust and lower weight. Using a nuclear thermal rocket as an upper stage roughly doubles or even triples the mass of a payload that can be launched into deep space,The Nuclear Cryogenic Propulsion Stage
Gizmag reports that NASA is working toward the design and flight validation of a 25,000 pounds of thrust nuclear thermal engine. It will weigh 40 tons fully fueled and will be 25 feet in diameter by 40 feet in length. The reactor will only be activated to go critical once the launch vehicle is in space to inhibit radioactive contamination in the event of a catastrophic accident. The engine will carry 220-330 pounds of non-weapons grade uranium. Development costs are estimated to be $4 billion over a 10-12 year period.
The development of the NCPS
The first step NASA is embarked on is to test and certify advanced materials with which to build the reactor core, according to Gizmag. For this purpose NASA will build a Nuclear Thermal Rocket Element Environmental Simulator (NTREES) that will test materials for the nuclear rocket in environmental safety.
Latest in a long line of nuclear rocket development projects
NASA has embarked on a number of nuclear thermal rocket development programs since the early 1960s. The most famous of these projects was called NERVA, which actually was ground tested and had developed a design for a flight ready engine before the project was officially terminated in 1973. NERVA was envisioned to be the engine that would have propelled an American manned spacecraft to Mars after having been launched on top of a Saturn V. But, with the end of the Apollo program and a lack of interest in manned space exploration extant in the 1970s, the project was cancelled. The NCPS project, according to Gizmag, will build on the work accomplished by NERVA, using materials that were not available in the 1960s.
Mark R. Whittington is the author of Children of Apollo and The Last Moonwalker. He has written on space subjects for a variety of periodicals, including The Houston Chronicle, The Washington Post, USA Today, the L.A. Times, and The Weekly Standard.