High Thrust In-Space Propulsion Technology Development R. Joseph Cassady Aerojet

1. High Thrust In-Space PropulsionTechnology DevelopmentR. Joseph CassadyAerojet 22 March 2011

2. Technology Development Needs a Framework • Critics attack the technology development efforts because they tend to “wander in the desert” • Lack of a defined destination is cited as a flaw by the critics • It is important to include ties to examine technologies with a framework that allows their relative merits to be examined in an applied manner – not abstract academic considerations! • In this same vein, it is important to look for synergies between technologies. This should be a Figure of Merit (FOM) • Elements that serve as building blocks and that are useful to multiple missions / destinations are also desireable – this is another key FOM An Example…

3. Architecture Study Framework Mission Phases Destinations Lunar Orbit or L-2 NEOs Phobos Mars Surface L2 In-Space Propulsion Options CrewCargo LOX/H2 LOX/H2 LOX/CH4 SEP NTR NTR ISRU Launch Propulsion Options SDLV (Baseline for Comparison) HC-ORSC Core HC-GG Core H2/O2 Core Solid/Liquid Booster Options Liquid Upper Stage Options Launch and In-Space Phases linked by: Total in-space mass and volume requirements Launch Vehicle/in-space hand-off orbit Launch Manifest Commonality opportunities ‹#›

4. Delivered Mass Requirements for Destinations DR=Direct Return O=Option Multi-Destination Mission Elements enables affordable approach ‹#›

5. In-Space Propulsion Options • Only included options which are realistic for next 20 years • Performance metrics were defined from already demonstrated ground testing • Complete Stage Mass models were developed for each technology to use in the Concepts of Operations • For each propulsion option we established several CONOPS options to trade • Crew and cargo split, direct return vs. LEO basing, LMO vs. Phobos, how Orion is used, ISRU, etc • IMLEO was then calculated for each CONOPs [i] Manzella, David, et. al., “Laboratory Model 50 kW Hall Thruster,” NASA TM-2002-211887, September 2002. [ii] Herman, Dan, “NASA’s Evolutionary Xenon Thruster (NEXT) Project Qualification Propellant Throughput Milestone: Performance, Erosion, and Thruster Service Life Prediction After 450 kg,” NASA TM-2010-216816, May 2010. [iii] Aerojet, “NASA Completes Altitude Testing of Aerojet Advanced Liquid Oxygen/Liquid Methane Rocket Engine,” May 4, 2010. [iv] http://www.astronautix.com/engines/rd58.htm, cited: January 17, 2011. ‹#›

6. Example CONOPS: Crew Segment of NEO Mission (Reusable Space Habitat Version) ‹#›

7. Example CONOPS: Crew Segment of Phobos Mission ‹#›

8. Conclusions from Architecture Comparison • High thrust in-space propulsion options include: • Lox-hydrogen for Earth departure • Lox-methane for landers and ascent vehicles • Nuclear thermal rockets for crew transit • Each of these shows benefits by itself, but can also be employed in a way in an overall architecture that enhances the standalone merits • Supporting technologies like ISRU (and SEP) provide major combinative benefit Aerojet ProprietaryAerojet Official Use Only

9. Final Comment • Selection of one technology as a principal thrust can have ripple impacts • From the example: • If ISRU were selected as a key long term investment priority, then a focus on lox-methane for deep space cryo stages (not EDS) would be advised • If NTR is selected as a key long term technology, then CFM for long duration storage of hydrogen would be advised and perhaps use of lox-hydrogen for deep space cryo stages is better Thank you for the opportunity to present Aerojet ProprietaryAerojet Official Use Only