Space Propulsion Overview

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Space Propulsion Overview

• Carl Dietrich
• Ph.D. Candidate, Aeronautics and Astronautics
• MIT Space Systems Laboratory
• chipd_at_mit.edu

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Propulsion How/what you push-off

• Without propellant
• Gravity assist (momentum exchange with large
  celestial bodies)
• ME tethers (momentum exchange with heavy masses
  in orbit)
• Electromagnetic accelerators/tethers (momentum
  exchange with field coils/Earths core)
• Solar sails (momentum exchange with photons)
• With propellant
• Rocket Engines (momentum exchange with on-board
  propellant)

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Rocket Propulsion
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Types of Rocket Propulsion

• Nuclear
• Matter-Antimatter Isp 1e7
• Fusion Isp 1e5s
• Gas core fission Isp 2500s
• Nuclear Thermal Rocket Isp 900s
• Chemical
• Solids Isp lt280s
• Hybrids Isp lt 350s
• Liquids Isp lt500s
• Electric
• Resistojets/Arcjets 500-1200s
• Hall Thrusters 800-2500s
• Ion engines 1500-10,000s
• Cold Gas Isp lt100s

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Chemical Rocket Fuels

• Typical Solids
• Fuel aluminum powder and HTPB binder
• Oxidizer ammonium perchlorate embedded in HTPB
  binder
• Typical Hybrids
• Fuel HTPB, plastics etc
• Oxidizer LOX, Nitrous Oxide, Hydrogen peroxide

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Liquid Chemical Rocket Fuels

• Monopropellant (catalytic decomposition)
• Hydrazine
• Hydrogen peroxide
• Bipropellant
• Hypergolic
• Nitrogen tetroxide Hydrazine
• Nitric Acid Furfuryl alcohol
• Non-hypergolic
• LOX-LH2
• LOX-Kerosene
• LOX-LNG

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Important propulsion system characteristics

• Performance
• Specific Impulse
• ThrustWeight
• Power requirements
• Fuel density (tank volume)
• Fuel handling procedures
• Spacecraft interface is it compatible with all
  other spacecraft systems? If not, what would
  need to be changed?
• Reliability/Flight History
• Cost? not a large driver for most missions

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Mission Requirements how you pick a propulsion
system

• Typically some delta-vee is a specified
  requirement for the propulsion system but not
  always
• Sometimes choice of propulsion system will change
  the required delta-V
• Sometimes other requirements are specified
• System mass
• System Thrust
• Restartable
• Particular firing frequency (transients)
• Throttling range
• Duration (dormant time and/or firing time)
• Maximum power consumption (electrics)
• Exhaust plume impingement restrictions
• Must use a particular fuel (ISRU)
• Recommended reading SMAD pp. 687-688 and Sutton
  Chapter 17

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Questions?
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What are your mission requirements?