NASA and DARPA have agreed to develop and test a rocket with a nuclear engine in space by 2027 (ref.). A nuclear reactor as an energy source would outperform chemical rocket engines and significantly reduce the expected timeline for the first human mission to Mars.
Obsolete Chemical Engines
Humans have made great strides in exploring and exploiting space in the last 60 years. But when it comes to propulsion, today’s rockets are essentially the same German V2 ballistic missiles from World War II. Over time, there have been innovations such as solar sails or ionic thrusters, but for crewed missions or those that have to move payloads, space agencies still rely on chemical propellant rockets.
However, these rockets have problems, and the biggest is that they work at their theoretical limits. Consider that chemical propulsion technology reached those limits in 1942. This means that crewed missions to the Moon can be limited, costly, and few, while a crewed mission to Mars is at the limit of technology. To overcome this barrier, engineers are seeking a more efficient and high-density energy propulsion based on nuclear reactor technology.
NASA made a serious attempt to develop a nuclear rocket for the last time in the 1960s with its Nuclear Engine for Rocket Vehicle Application (NERVA) and Rover projects, but these were abandoned to make way for the Apollo Mission. The last attempt by the American agency is the Demonstration Rocket for Agile Cislunar Operations (DRACO) program. The program is tasked with developing a nuclear engine that can send a mission to Mars and provide the US Space Force with a means to reach the Moon and move in the cislunar space with a short notice.
Nuclear Energy for Moon-Mars Missions
A nuclear thermal engine could heat a propellant to extremely high temperatures to generate thrust. Such a rocket could have efficiency over three times greater than that of a chemical fuel rocket. These properties would reduce travel times and allow for increased payload capacity. For a crewed mission to Mars, this would mean less exposure to cosmic radiation, fewer harmful effects due to lack of gravity, and less need for excessive flight systems and supplies.
In the new partnership between NASA and DARPA, the Space Technology Mission Directorate (STMD) will guide the development of the nuclear engine rocket. The propulsion system will be integrated into a DARPA spacecraft as a upper stage that will only function in space. “With this collaboration, we will leverage our experience gained from many previous nuclear energy and space propulsion projects” said Jim Reuter, STMD Associate Administrator. “Recent aerospace materials and engineering advancements are opening a new era for nuclear space technology. This flight demonstration will be a major milestone towards creating a space transportation capability for a Terra-Luna economy.”