TOPIC: X7 High Energy Space Systems (HESS)

• Propulsion system design concepts that address LOX/LH₂, as well as LOX/CH₄ and other LOX/Hydrocarbon engine and main propulsion systems integration issues;
  
• Integrated chemical propulsion system concepts that integrate primary propulsion and reaction control system elements;
  
• Design and analysis tools that significantly enhance the overall systems engineering evaluation of advanced chemical propulsion system concepts. These include tools for sensitivity analysis, quantification of system benefits to changes, propulsion system operability, "bottoms up" weight estimating, cost estimating, and reliability prediction for propulsion systems;
  
• Manufacturing techniques that allow for significant reduction in the cost and schedule required to fabricate engine and main propulsion system components. These techniques can use current or emerging processes and manufacturing technologies to develop engine and main propulsion system components that will reduce complexity, increase reliability, and that are easier to assemble, install, and test when integrated onto the vehicle;
  
• Concepts for solid or hybrid rockets that increase mass fraction, decrease the need for thermal insulation, and reduce or eliminate the need for staging; and
  
• High-performance advanced propellants (as indicated by high specific impulse and high specific impulse density) and non-toxic propellants that can significantly improve safety and cost of propulsion systems operations.
  

• X7.02 Chemical Propulsion Components
  
• X8.01 Vehicle Health Management Systems
  

• Advanced turbopumps with wider throttle range and improved cavitation control, plus specific turbomachinery components such as bearings, turbines, and impellers that demonstrate greater reliability and lifetime;
  
• Injectors with low thermal mass and long-duration reliability (e.g. for high duty-cycle attitude control thrusters);
  
• Long-life combustion chambers (e.g., based on use of advanced materials);
  
• Innovative thruster valve designs that tolerate high thermal loading due to heat soak-back during pulse mode operation;
  
• Innovative concepts for fast acting valves to enable use of larger thrusters for small impulses (i.e. spacecraft fine pointing);
  
• Highly-reliable long-duration seals;
  
• Long-life, high-reliability ignition systems;
  
• Lightweight, highly reliable gas compressors for pumping gaseous propellant into pressure vessels either in-flight or on a terrestrial surface;
  
• Novel pressurization approaches that minimize dissolution of pressurant gas in storable propellants (e.g., nitrogen tetroxide, hydrazine, and hydrazine derivatives)
  
• Novel concepts that increase performance or decrease mass of pressurization systems;
  
• Development of advanced materials that exhibit high compatibility with gaseous oxygen;
  
• Propulsion components based on microelectromechanical systems (MEMS) technology;
  
• Advanced nozzle concepts for in-space propulsion systems;
  
• Reaction control system thrusters that burn in situ and non-toxic propellants;
  
• Innovative thruster designs that minimize or prevent high heat soak-back during pulse mode operation;
  
• Highly reliable, lightweight compressors for use in gaseous propellant storage and distribution systems;
  
• Advanced lightweight multi-use positive expulsion devices for storable propulsion systems; and
  
• Other innovative chemical propulsion system components that improve system safety, affordability, or effectiveness.
  

• X3.03 Cryo and Thermal Management
  
• X7.01 Chemical Propulsion Systems and Modeling
  
• X8.01 Vehicle Health Management Systems
  

• Long-life, high-current cathodes (100,000 hours);
  
• Electric propulsion designs employing fuels that are more readily available (whether from Earth or in situ space resources) and easy to store/handle;
  
• Electrode thermal management technologies;
  
• Innovative plasma neutralization concepts;
  
• Metal propellant management systems and components;
  
• Cathodes for metal propellants;
  
• Low-mass, high-efficiency power electronics for RF and DC discharges;
  
• Lightweight, low-cost, high-efficiency power processing units;
  
• Low-voltage, high-temperature wire for electromagnets;
  
• High-temperature permanent magnets and/or electromagnets;
  
• Application of advanced materials for electrodes and wiring;
  
• Highly accurate propellant control devices/schemes;
  
• Miniature propellant flow meters;
  
• Lightweight, long-life storage systems for krypton and/or hydrogen;
  
• Fast-acting, very long-life valves and switches for pulsed inductive thrusters;
  
• Superconducting magnets;
  
• Lightweight thrust vector control for high-power thrusters; and
  
• High fidelity methods of determining the thrust of ion, Hall, and advanced plasma engines without using conventional thrust-stands.
  

• Low- to medium-power solar electric propulsion for planetary science missions (S8.04 Spacecraft Propulsion).
  

• Innovative aeroassist system designs. This includes low-mass, rigid aeroassist systems based on robust, high-temperature structures and adhesives, modular or deployable/inflatable aeroshells with large surface area, and inflatable ballutes;
  
• TPS designs for human-rated aeroassist vehicles returning to Earth from the Moon and Mars, and for Mars aerocapture and Entry, Descent and Landing (EDL). Innovative TPS concepts are solicited to reduce current TPS mass fractions by 25% to 50% and to reduce TPS costs;
  
• Ablative and reusable TPS materials and concepts that significantly enhance performance and reduce mass. This includes development and characterization of single- and multi-use TPS materials, TPS for rigid aeroshells, and flexible TPS materials for deployable aeroshells. Thermo-chemical and mechanical properties data for probabilistic design, spallation characteristics, and accurate simulation tools to predict material behaviors and material compatibility are required. Innovative TPS concepts are solicited to reduce current TPS mass fractions by 25% to 50% and to reduce TPS costs;
  
• Aerothermodynamic modeling tools with greater accuracy and less uncertainty: (1) Innovative and accurate computer modeling of fluid structure interactions, including flow stability and surface deflections under dynamic conditions for decelerator deployment and inflation; (2) Modeling and simulation of convection/radiation/ablation coupled three-dimensional flow fields, for both optically thick and thin shock layers and highly ionized flows; (3) Accurate prediction of wake heating including radiative heating components; (4) Accurate prediction of single and multiple rocket plume effects (e.g., reaction control system thrusters) on the vehicle aerodynamics and heating;
  
• Innovative sensor systems which are capable of providing real-time or near real-time updates to atmospheric pressure, temperature, density, and winds to support the guidance systems used on aeroassist vehicles;
  
• Innovative sensor systems for inflatable aeroassist vehicles capable of providing real time aerosurface temperature, strain, deflection, flight loads and other significant parameters; and
  
• Lightweight flexible materials that will reduce the mass and increase the strength and thermal characteristics for applications to deployable aeroshells and supersonic deployed decelerators.
  

• Earth return of piloted spacecraft from the Moon. Return-to-Earth scenarios for human lunar missions include: (1) short-range direct entry and landing; (2) extended-range entry using a skip out of the atmosphere with subsequent EDL to the Earth's surface; and (3) aerocapture into a low-energy Earth orbit followed by EDL. Inertial arrival speeds of approximately 11 km/s (up to 12 km/s for some abort scenarios) with entry masses of at least 5 metric tons are expected for normal lunar return. Acceptable sustained loads for these piloted missions are limited to about 5 gs perpendicular to the human spine in the "eye balls in" direction; and
  
• Mars precursor missions for human exploration. These include robotic missions designed to deliver pre-deployed cargo or to conduct technology demonstrations in anticipation of follow-on human Mars missions. Candidate human mission scenarios for Mars include human and cargo aerocapture into a Mars orbit followed by EDL to the Mars surface and return to Earth. Mars aerocapture missions are expected to have arrival speeds of 6 to 8 km/s and aerocapture mass on the order of many 10s of metric tons. Return-to-Earth scenarios for human Mars missions are similar to those for lunar missions, except for higher arrival speeds (11.5 - 12.5 km/s, up to 14 km/s for some off-nominal scenarios).
  

• Inflatable and other innovative structures (X2.02 Structures and Habitats); and
  
• Aeroassist systems for deep space robotic science missions (S5.01 Low Thrust and Propellantless Propulsion Technologies).
  

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