Space Nuclear Propulsion for Human Mars Exploration (2021) / Chapter Skim
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4 System and Programmatic Issues
4 System and Programmatic Issues
Pages 55-61
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From page 55... ...
NTP systems and NEP systems (which include a chemical propulsion system) are composed of many technologies, including the following: • NTP and NEP -- Nuclear reactors -- Shields -- Cryogenic fluid management • NTP specific -- Turbomachinery, valves, and pipes -- Nozzles -- Long-term storage of liquid hydrogen (LH2)
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From page 56... ...
NASA should develop consistent figures of merit and technical expertise to allow for an objective comparison of the ability of nuclear electric propulsion and nuclear thermal propulsion systems to meet requirements for a 2039 launch of the baseline mission. DEVELOPMENTS COMMON TO BOTH NTP AND NEP SYSTEMS Despite the many differences between NEP and NTP systems and subsystems, there are some areas of synergy, including the following: • Nuclear reactor fuels.
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From page 57... ...
NEP and NTP systems require, albeit to different levels, significant maturation in areas such as nuclear reactor fuels, materials, and additional reactor technologies; cryogenic fluid management; M&S; testing; safety; and regulatory approvals. Given these commonalities, some development work in these areas can proceed independently of the selection of a particular space nuclear propulsion system.
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From page 58... ...
In contrast, HEU NTP reactors have been built, tested, and benchmarked using prior M&S software. Technical feasibility and difficulty considerations favor HEU for NTP systems, but they do not clearly favor one fuel enrichment level over the other for NEP systems.
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From page 59... ...
In the near term, NASA and the Department of Energy, with inputs from other key stakeholders, including commercial industry and academia, should conduct a comprehensive assessment of the relative merits and challenges of highly enriched uranium and high-assay, low-enriched uranium fuels for nuclear thermal propulsion and nuclear electric propulsion systems as applied to the baseline mission. INDUSTRIAL BASE A growing number of private-sector companies are developing system concepts for space nuclear systems.
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From page 60... ...
The fundamental NEP challenge is to scale up the operating power of each NEP subsystem and to develop an integrated NEP system suitable for the baseline mission. PROGRAMMATICS The roadmaps of Sections 2.6 and 3.6 show the key milestones necessary to execute the baseline 2039 human Mars mission preceded by cargo missions beginning in the 2033 opportunity.
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From page 61... ...
for power generation, 1 to 2 years for thrust) Scale • Power conversion and thermal subsystem tests conducted to date have been at power levels orders of magnitude below that required for baseline mission • Limited full-scale, short duration electric propulsion subsystem testing at power levels an order of magnitude below that required for baseline mission Ground-Based Testing • Need to capture and process engine exhaust • No fully integrated system testing experience (resulting in high cost)
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