NASA Proposal to Revive Nuclear Thermal Space Propulsion Development

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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