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NASA Proposal to Revive Nuclear Thermal Space Propulsion Development

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Nuclear Thermal Rocket Propulsion for Future Human Exploration Missions (24 pages)

The presentation was made on June 27, 2012 for the NASA Future in Space Operations workshops

• Nuclear Thermal Propulsion (NTP) is a proven technology; 20 NTR / reactors designed, built and tested at the Nevada Test Site (NTS) in the Rover / NERVA programs

• “All the requirements for a human mission to Mars were demonstrated” – thrust level, hydrogen exhaust temperature, max burn duration, total burn time at power, #restarts

• The smallest engine tested in the Rover program, the 25 klbf “Pewee” engine, is sufficient
for human Mars missions when used in a clustered engine arrangement – No major scale ups are required as with other advanced propulsion / power systems

• In less than 5 years, 4 different thrust engines tested (50, 75, 250, 25 klbf – in that order)
using a common fuel element design – Pewee was the highest performing engine

• “Common fuel element” approach used in the AISP / NCPS projects to design a small (~7.5 klbf), affordable engine for ground testing by 2020 followed by a flight technology
demonstration mission in 2023. PWR sees strong synergy between NTP and chemical

• SAFE (Subsurface Active Filtration of Exhaust) ground testing at NTS is baseline; capital cost for test HDW is ~45 M$ with ~ 2M$ for each additional engine test (NTS Dec. 2011)

• Cost for engine development and ground testing will not “break the bank” & the system will have broad application ranging from robotic to human exploration missions

• NTP consistently identified as “preferred propulsion option” for human Mars missions:
– NASA’s SEI – Stafford Report (1991) listed NTP as #2 priority after HLV
– NASA’s Mars Design Reference Missions (DRMs) 1 (1993) – 4 (1999)
– NASA’s Design Reference Architecture (DRA) 5.0 (2009)

• Using NTP, the launch mass savings over “All Chemical” and “Chemical / Aerobrake” systems amounts to 400+ metric tons (~ISS mass) or ~4 or more HLVs. At ~1 B$ per HLV, the launch vehicle cost savings alone can pay for NTP development effort

• The DRA 5.0 crewed MTV “Copernicus” has significant capability allowing reusable “1-yr” NEA missions & short (~1.5 yrs) Mars / Phobos orbital missions before a landing

• JSC’s “NEA Accessibility Study” presented by Bret Drake to Doug Cooke (April 7, 2011). Findings: NTR outperforms chemical, SEP/Chemical & all SEP systems, allowing access to more NEAs over larger range of sizes and round trip times for fewer HLV launches.

• With more LH2, faster “1-way” transit times to from Mars are possible if desired

• Lastly, NTP has significant growth capability (other fuels, bimodal & LANTR operation)

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