A report recently published by the National Academies committee concluded NASA needs to kick off an aggressive technology development campaign for space nuclear propulsion technologies. The aggressive campaign is necessary if NASA wants to use the technology for human missions to Mars within the next two decades.
The report was published on February 12 and was sponsored by NASA. It found that both nuclear thermal propulsion (NTP) and nuclear electric propulsion (NEP) have significant hurdles to overcome before they can be used in a 2039 human mission to Mars. The big benefit of nuclear propulsion for Mars missions is that the propulsion systems could significantly reduce the travel time.
A faster travel time is critical as the mission would require fewer resources, and astronauts would be subjected to less radiation. Between the two technologies, the report favors NTP. With NTP, a nuclear reactor heats fuel, such as liquid hydrogen, to generate thrust. The report believes that an aggressive program could develop NTP systems capable of executing a Martian mission by 2039
The technology does face significant hurdles to coming to reality that extend well beyond creating the nuclear reactor itself. The propellant would have to be heated to a temperature of 2700 kelvins, and the system would have to bring the propellant up to operating temperature within one minute. One major challenge is no ground-based testing facility for NTP systems and the difficulty of storing liquid hydrogen for the mission’s duration.
Using NEP, the nuclear reactor would generate power for electric thrusters. The challenge with this system is that it has to be scaled to power levels far beyond what’s currently available for both power and thermal management systems to work with megawatt-class reactors. The report also found that there has been little progress on relevant technologies since 2005.