NASA Technology Roadmap: Launch Propulsion Systems

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NASA Technology RoadmapLaunch Propulsion Systems

• Robert J. Santoro
• The Propulsion Engineering Research Center
• The Pennsylvania State Unversity
• University Park, PA 16802

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Context for Current NASA Planning

• No access to low earth orbit (LEO) after Space
  Shuttle retirement.
• Access to Space Station dependent on Soyuz in the
  near term.
• Decision to enable and rely on commercial space
  launch capabilities to provide access to LEO in
  the near term and eventually beyond LEO.
• 2011 NASA Strategic Plan notes current U.S.
  launch capability for many planetary missions
  only possible using Delta and Atlas vehicles.

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Other Challenges

• NASA has not developed a new rocket launch engine
  or vehicle since the Space Shuttle.
• All NASA personnel with experience on Saturn V
  program (LOX/RP engine) have retired or died.
• Most of the engineers that worked on the Space
  Shuttle development program have or will soon
  retire.
• Current NASA or U.S. commercial space vehicle
  workforce has little or no experience with system
  integration challenges of developing a new
  launch vehicle engine or a new vehicle.

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Commercial Launch Vehicles

• Promising launch vehicles such as the Space-X
  Falcon 9 and Orbital Sciences Taurus II rely on
  old engine technology such as the former TRW
  pintle-based injector technology or the Russian
  NK-33 engine, respectively.
• Use of innovations related to advances in
  lighter, stronger materials and electronics for
  Avionics, Guidance/Navigation/Control have
  impacted reliability and lowered cost for these
  vehicles.

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• What technologies should NASA invest in to make
  the biggest difference in terms of
• a) increasing capabilities to do NASAs space
  missions or
• b) lowering the cost for those missions?

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Lowering Costs

• The NASA rocket-based combined cycle (RBCC)
  program showed the biggest factor in lowering
  costs is flight rate.
• Costs for launching payloads for 500-1000 per
  pound requires flight rates of 100 to 200 flights
  per year, which is probably true for reusable as
  well as expendable vehicles
• Reduce parts count, which increases reliability
  and decreases needed inventories

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Lowering costs for Reusable Vehicles

• Reduce the number of people required to turn
  around the vehicle for the next flight.
• Use propellants that do not require special
  handling for worker health and safety (e.g.
  N2O4).
• Design for easy access for servicing vehicle.
• Service at landing site

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Near term (5 years) most important technology for
NASA investment

• Development of a highly reliable chemical rocket
  engine for launch applications
• Propellant selection is very important and has
  two options
• LOX/LH2 draws on current NASA knowledge and
  experience base.
• LOX/RP has superior fuel mass density as compared
  to LH2 that significantly affects fuel tank size
  and weight which is reflected in vehicle mass.
  In my opinion, LOX/RP is the correct technical
  choice. However, LOX/RP engines have not been a
  focus of NASA since the Saturn V program and
  will require a steeper learning curve.

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Longer term (20 years) most important technology
for NASA investment

• Development of a two-stage, combined cycle
  vehicle for space access to LEO and beyond.
• Game changing development in terms of access to
  space and cost
• Either TBCC or RBCC should be pursued at first
  with the focus on the high speed turbine
  technology for TBCC. For RBCC focus on the the
  rocket ejector system. Both require the same
  ram/supersonic cycles in the full engine
  operation
• Second stage should be a more conventional liquid
  chemical rocket engine, likely using LOX/LH2.

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Rationale for NASA to develop a Two-Stage
Combined-Cycle engine

• Complexity of engine requires the broad rocket
  and air-breathing expertise found in NASA.
• First stage would be reusable and more like
  current aircraft operation.
• First stage operation using air reduces
  propellant weight while operating at lower
  chamber pressure and reduced parts count.
• Second stage could provide wide payload size
  flexibility through sizing of this stage.

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Other projects of merit

• Pulse detonation engines for both closed cycles
  (rockets) and open cycles (air breathing
  engines).
• Game changing potential due to higher Isp and
  fewer moving parts.
• Potential to reduced operating pressures of
  turbomachinery for rocket engines and fewer
  compressor stages for high compression ratio jet
  engine applications.
• New upper stage rocket engine using shuttle
  derived or expander cycle.

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Constructive Criticisms

• Due to current budget and mission uncertainty,
  the technology roadmap is very broad and will
  need to be focused early in the program.
• The Fundamental Liquid Propulsion Technology
  (1.2.6) TRL 1-3 level effort should be extended
  from two years to five years. There still is a
  need for more fundamental research on specific
  areas (e.g. combustion instability).

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Questions????