Space Nuclear Propulsion for Human Mars Exploration (2021)
Chapter: Appendix A: Statement of Task and Additional Guidance
A
Statement of Task and Additional Guidance
STATEMENT OF TASK
The National Academies of Sciences, Engineering, and Medicine will convene an ad hoc committee to identify primary technical and programmatic challenges, merits, and risks for developing and demonstrating space nuclear propulsion technologies of interest to future exploration missions. Nuclear propulsion has been shown to offer the potential for rapid human transit to Mars with one-way transit times less than 9 months and total roundtrip times including Mars surface stays less than 3 years. The committee will also determine the key milestones and a top-level development and demonstration roadmap for each technology. Additionally, the committee will identify missions that could be enabled by successful development of each technology.
The space nuclear propulsion technologies of specific interest are:
- High-performance nuclear thermal propulsion (NTP) that heats hydrogen propellant to 2500 K or more and produces specific impulse of at least 900 s.
- Nuclear electric propulsion (NEP) that converts thermal energy to electricity to power plasma thrusters for highly efficient and rapid transport of large payloads (e.g., a propulsion system with a power level of at least 1 MWe and a mass-to-power ratio (kg/kWe) that is substantially lower than the current state of the art of NEP systems).
ADDITIONAL STUDY PARAMETERS
After the committee was appointed, NASA further requested that the committee’s assessment be conducted in reference to a specific baseline mission: the launch of a crewed, opposition-class mission to Mars in 2039, which would be preceded by cargo missions beginning in 2033. The committee accepted this additional guidance in preparing this report.
The committee also determined that an NTP system with a hydrogen propellant temperature of approximately 2700 K at the reactor exist corresponds to a specific impulse of at 900 Isp, and so the report consistently refers to 2700 K rather than 2500 K as the target propellant temperature.
