Participating MD(s): SMD, STMD

This subtopic seeks innovations to meet SMD propulsion in chemical and electric propulsion systems related to sample return missions to Mars, small bodies (like asteroids, comets, and Near-Earth Objects), outer planet moons, and Venus. Additional electric propulsion technology innovations are also sought to enable low cost systems for Discovery class missions, and low-power, nuclear electric propulsion (NEP) missions. Roadmaps for propulsion technologies can be found from the National Research Council (http://www.nap.edu/openbook.php?record_id=13354&page=168) and NASA’s Office of the Chief Technologist (http://www.nasa.gov/pdf/501329main_TA02-InSpaceProp-DRAFT-Nov2010-A.pdf).

This subtopic seeks proposals that mature iodine propulsion technologies, including:

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  Iodine compatible Hall Effect Thruster cathodes with lifetimes greater than 10,000 hours.
  
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  Robust and electrically efficient iodine storage and delivery system architectures (scalable 5 kg to 100 kg iodine):
  
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    Numerical modeling to guide system design and CONOPS, predicting power consumption, iodine mobility, thermal transport, sublimation rate, condensation, clogging, recovery time post-anomalies, etc.
    
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    Design and analysis of innovative iodine feed system architectures.
    
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    Experimental demonstration of promising feed system architectures under conditions of long-term iodine storage and dynamic thermal environments.
    
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  Compact low-power iodine compatible feed system technologies, including high accuracy pressure sensors (<1 atm full scale), propellant flow control valves, latch valves, heaters, etc.
  
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    Feed system technologies utilizing innovative iodine resistant materials and coating.
    
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    Experimental and numerical demonstration of component operation in dynamic simulated mission environments.
    

This subtopic also seeks proposals that explore uses of technologies that will provide superior performance in for high specific impulse/low mass electric propulsion systems at low cost. These technologies include:

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  Thruster components including, but not limited to, advanced cathodes, rf devices, advanced grids, lower-cost components enabled by novel manufacturing techniques.
  
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  Any long-life, electric propulsion technology between 1 to 10 kW/thruster that would enable a low-power nuclear electric propulsion system based on a kilopower nuclear reactor.
  

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  Chemical and/or electric propulsion systems with green/non-toxic propellants.
  
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  Improved operational life over SOA propulsion systems.
  

In addressing technology requirements, proposers should identify potential mission applications and quantify the expected advancement over state-of-the-art alternatives.

 

Solar/Electric Sail Propulsion
This subtopic seeks sail propulsion innovations in three areas for future robotic science and exploration missions:

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  Large solar sail propulsion systems with at least 1000 square meters of deployed surface area for small (<150 kg) spacecraft to enable multiple Heliophysics missions of interest.
  
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  Electric sail propulsion systems capable of achieving at least 1 mm/sec2 characteristic acceleration to support Heliophysics missions of interest and rapid outer solar system exploration.
  
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  Electrodynamic tether/sail propulsion systems capable generating from the Lorentz Force delta-V sufficient to de-orbit from altitudes up to 2,000 km and to maintain a small (< 500 kg) spacecraft in LEO at altitudes up to 400 km for 5 years enabling Earth ionospheric and plasmasphere investigations.
  

Design solutions must demonstrate high deployment reliability and predictability with minimum mass and launch volume and maximum strength, stiffness, stability, and durability.

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  Novel design, packaging, and deployment concepts.
  
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  Lightweight, compact components including booms, substrates, and mechanisms.
  
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  Validated modeling, analysis, and simulation techniques.
  
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  Ground and in-space test methods.
  
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  High-fidelity, functioning laboratory models.
  

Z10.01 Cryogenic Fluid Management

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  Analysis of cryogenic systems for improved modeling of turbulence effects on heat and mass transfer across the liquid/gas interface. Of particular interest are improved models for turbulent heat transfer and mass transfer across the liquid/gas interface that can be applied to Unsteady Reynolds Averaged Navier-Stokes (URANS) simulations using Eulerian-based two-phase models, such as Volume of Fluid. Data to guide modeling efforts such as NASA-TM-2003-212926 or NASA-TM-105411.
  
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  Mars surface cryogenic storage requires a vacuum jacket in order to reduce heat leak and power requirements. A lightweight vacuum jacketed system may be possible, where the vacuum jacket is designed for Mars atmospheric pressure (5-7 torr). The vacuum jacket may be launched purged, evacuated upon reaching orbit, and then sealed prior to Mars entry. The vacuum jacketed system would then have to retain a vacuum for several years while on the surface of Mars.
  
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  New and improved technologies that provide for the densification (or sub-cooling) of cryogenic propellants. Propellant conditioning systems that allow for the production and maintenance of densified propellants that support operations including transfer and low-loss storage are of prime interest for future space vehicle and ground launch processing facilities.
  
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  Analysis of cryogenic systems sometimes requires computational fluid dynamics, especially when significant deformation or breakup of the liquid/gas interface occurs. For many components, or for settled conditions, a simpler fluid and thermal network approach may be sufficient. Of interest is the capability to tightly couple CFD and fluid/thermal network approaches, such as a fluid-thermal network analysis of an active pressure control system coupled to a CFD simulation of the fluid and thermodynamics occurring in a cryogenic storage tank.
  

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  Components for integrated RCS (~100-lb class) and Main Propulsion System (MPS) (25,000-lb class) feed systems (utilizing common propulsion tanks), including:
  
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    Lower power (~100 - 30 W) electric-pump systems (28-100 Vdc) at desired flowrates (~8-10 lbm/s max).
    
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    Vacuum capable (<10 torr) compact exciters with high spark rates (>200 sps) and 30-50 mJ minimum delivered spark energy.
    
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    Improved materials/manufacturing capabilities for high temperature (>800 K), high pressure (>1000 psia) applications.
    
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  Technologies to improve throttling in pressure-fed engines (5000-lb class), to minimize performance losses, such as:
  
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    Improved injector concepts that provide at least 98% c* (c-star) efficiency at full throttle conditions and maintain stability at 20% throttle ratios.
    
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    Fast-acting (<80 ms response time), low-leakage (<3 SCCS to 0.1 SCCS gaseous propellants) throttle valves, which meet the following performance considerations: maintain consistent mixture ratio (MR) over the throttle range, 50% (minimum) force margin, cold and warm operations, easily chilled in.
    

Proposers MUST clearly articulate the metrics of their technology, and must show a clear understanding of the current state of the art (SOA), and explicitly describe how their technology advances the state of the art. A clearly defined description of the following, at a minimum, is desired:

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  Assessment of SOA with the key performance parameters (KPP) of their choosing (such as performance, mass, response time, etc.), including specifics which may be referenced in backup material - provide SOA for each major technology element in the proposal.
  
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  Address the outstanding technology performance being promised and the degree to which the concept is new, different, and important. Particularly, explicitly define how the technology and/or fabrication technique proposed saves cost, schedule and/or mass. If a new manufacturing technique is proposed, clearly define how the technique provides a unique technology not feasible through other manufacturing methods.
  
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  Provide quantitative rather than qualitative assertions (e.g., x% improvement of y, z kg of mass savings, xx% in cost savings, etc.) to the advancement over the SOA.
  
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  Identify specific deliverables being offered. Clearly and explicitly specify what items are being delivered as part of contract performance, and clearly identify if hardware is being offered. Explicitly identify if any commitment has been made for post-development testing.
  

Phase I Deliverables - Research to identify and evaluate candidate technology applications to demonstrate the technical feasibility and show a path towards a demonstration. Bench or lab-level demonstrations are desirable. The technology concept at the end of Phase I should be at a TRL of 4 to 5.

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  Reactor fuel element designs with high temperature (> 2600K), high power density (>5 MW/L) to optimize hydrogen propellant heating.
  
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  New additive manufacturing processes to quickly manufacture the fuel with uniform channel coatings and/or claddings that reduce fission product gas release and reactor particulates into the engines exhaust stream. Fuel can made of Ceramic-metallic (cermet) or composite/carbide designs:
  
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    New fuel element geometries which are easy to manufacture and coat, and better performing than the traditional prismatic fuel geometries with small through holes with coatings.
    
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    Insulator design (one application is for tie tubes) which has very low thermal conductivity and neutron absorption, withstands high temperatures, compatible with hot hydrogen and radiation environment, and light weight.
    

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  Concepts to cool down the reactor decay heat after shutdown to minimize the amount of open cycle propellant used in each engine shutdown. (Depending on the engine run time for a single burn, cool down time can take many hours.)
  
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  Low risk reactor design features which allow more criticality control flexibility during burns beyond the reactor circumferential rotating control drums, and/or provide nuclear safety for ground processing, launch, and possible launch aborts:
  
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    Control of criticality with water submersion and compaction accidents.
    
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    Concept for quick restart of reactor (2-6 hours) after 30-40 minute burns and accounting for Xe135 buildup.
    
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  Radiation shielding concepts that protect the crew and minimize heating of store propellant and the stage. Strategies that minimize radiation shielding system mass, such as utilization of the payload and consumables for shielding (when practical) that may provide an additional bonus of shielding galactic cosmic radiation as well as radiation from the NTP engines.
  

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  Advanced high-temperature and hydrogen embrittlement resistant materials for use in a hot hydrogen environment (<5500°F) and possibly exposed to neutrons and gamma rays.
  
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  Efficient generation of high temperature, high flow rate hydrogen (<30 lb/sec).
  
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  Devices for measurement of radiation, pressure, temperature and strain in a high temperature and radiation environment:
  
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    Non-intrusive diagnostic technology to monitor engine exhaust for fuel element erosion/failure and release of radioactive particulates.
    
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  Effluent scrubber technologies for efficient filtering and management of high temperature, high flow hydrogen exhausts. Specific interests include:
  
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    Filtering of radioactive particles and debris from exhaust stream having an efficiency rating greater than 99.5%.
    
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    Removal of radioactive halogens, noble gases and vapor phase contaminants from a high flow exhaust stream with an efficiency rating greater than 99.5%.
    
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  Applicable Integrated System Health Monitoring and autonomous test operations control systems.
  
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  Modern robotics which can be used to inspect the ground test system exposed to a radiation environment.
  

For all above technologies, research should be conducted to demonstrate technical feasibility during Phase I and show a path towards Phase II hardware/software demonstration with delivery of a demonstration unit or software package for NASA testing at the completion of the Phase II contract.