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

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High Thrust In-Space PropulsionTechnology
DevelopmentR. Joseph CassadyAerojet
22 March 2011
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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
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Architecture Study Framework
Mission Phases
Destinations Lunar Orbit or L-2 NEOs Phobos Mars
Surface
L2
In-Space Propulsion Options Crew
Cargo 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
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Delivered Mass Requirements for Destinations



DRDirect Return OOption
Multi-Destination Mission Elements enables
affordable approach
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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

Element Propellant Specific Impulse, s Thrust
Cryogenic Propulsion(1 p.432) LOX/LH2 452 67 222kN (5-50klbf) descent/ascent thrust was not yet evaluated
Soft Cryogenic Propulsion LOX/CH4 350 67 222kN (5-50klbf) descent/ascent thrust was not yet evaluated
Semi-Cryogenic Propulsion LOX/RP1 349 67 222kN (5-50klbf) descent/ascent thrust was not yet evaluated
Nuclear Thermal Rocket(2 p.25) LH2 900 67 222kN (5-50klbf) descent/ascent thrust was not yet evaluated
Hall Thruster Systems ( p.11) Xenon or Krypton 3000 40mN/kW or 32mN/kW
Gridded Ion Thruster Systems Xenon 6000 25mN/kW

• 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, NASAs
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.
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Example CONOPS Crew Segment of NEO Mission
(Reusable Space Habitat Version)
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Example CONOPS Crew Segment of Phobos Mission
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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

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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