DailyTech reports the Russian Federal Space Agency is working on a new Nuclear Gas Core Reactor (NGCR) powered spacecraft with the aim of reaching Mars and setting up a base on the Moon. The design of this new propulsion engine is expected to be finalized by 2012, and full development would take about nine years. The projected cost is 17 billion rubles, about $580 million.
The Nuclear Gas Core Reactor (NGCR) uses highly enriched uranium (U-235 or U-233) injected into a gas jet at pressures of up to 1000 atm and temperatures of up to 70000 K. Hydrogen is used as a propellant as it provides a high specific impulse. The fissile core is a cylindrical design and energy is delivered to the hydrogen propellant via alkali metal vapors like Li. Due to the distance between the walls and nozzle and the fission reactions in the core, the rocket can achieve higher temperature fission and thus greater specific impulse than solid-core designs.
A key challenge will be developing the theory to full predict the behavior of and contain the fission plasma via a magnetic field. Russia has already done a good deal of work into this topic, but many questions remain unanswered, particularly how the field will react to instability from gravity and inertial forces.