- API data.nasa.gov | Last Updated 2018-07-19T18:20:37.000Z
One of the key motivating factors for using particle filters for prognostics is the ability to include model parameters as part of the state vector to be estimated. This performs model adaptation in conjunction with state tracking, and thus, produces a tuned model that can used for long term predictions. This feature of particle filters works in most part due to the fact that they are not subject to the “curse of dimensionality”, i.e. the exponential growth of computational complexity with state dimension. However, in practice, this property holds for “well-designed” particle filters only as dimensionality increases. This paper explores the notion of wellness of design in the context of predicting remaining useful life for individual discharge cycles of Li-ion batteries. Prognostic metrics are used to analyze the tradeoff between different model designs and prediction performance. Results demonstrate how sensitivity analysis may be used to arrive at a well- designed prognostic model that can take advantage of the model adaptation properties of a particle filter.*
Precision Membrane Optical Shell (PMOS) Technology for RF/Microwave to Lightweight LIDAR Apertures, Phase IIdata.nasa.gov | Last Updated 2018-07-19T16:02:57.000Z
Membrane Optical Shell Technology (MOST) is an innovative combination of 1) very low areal density (40 to 200g/m2) optically smooth (<20 nm rms), metallic coated reflective membrane thin films, 2) advanced fabrication techniques that transform the films into self supporting shells through the introduction of permanent optically relevant double curvature, and 3) discrete active boundary control to enable rigid body alignment and maintainment of surface figure in face of environmental disturbances. Areal densities of better than 2 kg/m2 (including actuators) are projected. Current measured surface figure is ≈1 to 10 microns rms at up to the 15 cm size, and we are poised for further improvements. Demonstrated material and fabrication techniques are scaleable to at least the 2m+ diameter single surface apertures and larger apertures are possible through segmentation techniques. Proven stowage and deployment techniques enable space flight application. We propose advancing 1) the basic fabrication technology and 2) the TRL level of MOST apertures for ground and space based apertures. The key resulting innovation is implementation of low areal density, compact roll stowable approaches to realize low mass, low cost reflective apertures for RF/Microwave to LIDAR. Other NASA and DOD applications are expected as precision and aperture size increase.
- API data.nasa.gov | Last Updated 2018-07-19T08:09:47.000Z
An on-board oxygen concentrator is required during long duration manned space missions to supply medical oxygen. The commercial medical oxygen generators based on pressure swing adsorption (PSA) are large and highly power intensive. TDA Research, Inc. (TDA) proposes to develop a small, lightweight, portable oxygen generator based on a vacuum swing adsorption (VSA) to produce concentrated medical oxygen. The unit uses ambient vehicle cabin air as the feed and delivers high purity oxygen while meeting NASA's requirements for high flow capacity, closed-loop tissue oxygen control and operation in microgravity/partial gravity. TDA's VSA system uses a modified version of the lithium exchanged low silica X zeolite (Li-LSX), a state-of-the-art air separation sorbent extensively used in commercial Portable Oxygen Concentrators (POCs) to enhance the N2 adsorption capacity. In Phase I, we demonstrated the scientific, technical, and commercial feasibility of the oxygen concentrator module (OCM). In Phase II, we will develop a higher fidelity prototype with an adjustable pressure output to produce 2-15 lpm of O2 at 50% to +90% purity from ambient cabin air. The OCM will be capable of self-regulating the oxygenation of the patient using a closed loop feedback system that senses tissue oxygenation level. We will evaluate the sorbent performance in a breadboard bench-scale prototype under simulated microgravity/partial gravity exploration atmospheres and carry out a 1,500 hr longevity test (at a minimum) to determine its mechanical durability. Based on the experimental results, we will design a prototype unit that will meet all of NASA's requirements (e.g., low power draw over the range of flows and oxygen levels, lightweight and volume), while delivering the desired oxygen flow and purity.
- API data.nasa.gov | Last Updated 2018-07-19T09:06:28.000Z
With the Titan Saturn System Mission, NASA is proposing to send a Montgolfiere balloon to probe the atmosphere of Titan. To better plan this mission and create a robust optimized balloon design, NASA requires the ability to more accurately evaluate the convective heat transfer characteristics of the balloon operating in Titan's atmosphere. Based on limitations of previous efforts, NASA has requested proposals for a testbed to support CFD validation. Leveraging the results of the Phase I effort, Near Space Corporation (NSC), proposes to develop and operate two full scale Testbeds (~9 m diameter) in order to help validate CFD models for the TSSM Titan Montgolfiere balloon. The Testbeds will incorporate new envelope design innovations and state-of-the-art data acquisition methods to enable data intensive tethered and free-flight tests. Utilizing its unique balloon facility located in a large blimp hangar, NSC will conduct iterative tethered hangar tests of the full scale Testbeds (which is not possible in existing cryogenic test chambers). These flights will enable better IR imaging and flow characterization measurements. The acquired data will provide critical input to incrementally improve and validate the CFD models. The outdoor drop/inflation test and a free flight test will retire technology risks associated with the future Titan mission in addition to generating the validation data necessary to improve the existing CFD models. NSC proposes to develop and operate a mature TMTT system during Phase II, generate pertinent data that will be used to improve the CFD models, and leverage the effort to create valuable technology with both NASA and non-NASA commercial applications.
Characterization and Mitigation of Radiation and High Temperature Effects in SiC Power Electronics, Phase IIdata.nasa.gov | Last Updated 2018-07-19T07:46:14.000Z
Future NASA science and exploration missions require significant performance improvements over the state-of-the-art in Power Management and Distribution (PMAD) systems. Space qualified, high voltage power electronics can lead to higher efficiency and reduced mass at the spacecraft system architecture level, and serve as an enabling technology for operational concepts such as solar electric propulsion. Silicon carbide (SiC) is a robust technology with superior electronic properties for power applications. SiC devices offer higher temperature operation, lower on-resistance, higher breakdown voltages, and higher power conversion efficiency than silicon devices. However, high vulnerability to heavy-ion induced degradation and catastrophic failure has precluded this technology from space PMAD applications. Importantly, physical mechanisms for this vulnerability are not well understood, resulting in the inability to develop radiation hardened SiC devices. CFDRC, in collaboration with Vanderbilt University and Wolfspeed, is applying a coupled experimental and physics-based modeling approach to address this challenge. In Phase I, we performed electrical and heavy ion tests on 1200V Wolfspeed SiC JBS diodes to generate response data, and performed TCAD simulations to investigate diode sensitivity to design parameters and analyze electro-thermal mechanisms behind measured response. In Phase II, we will develop further insight into physical mechanisms in the diodes via development and application of advanced physics models. We will parametrically analyze design features to identify promising hardness solutions, which will then be fabricated and experimentally characterized. We will also perform heavy-ion testing of 1200V SiC MOSFETs and apply simulations for insights into governing mechanisms (to be further developed in follow on work). Direct participation by Wolfspeed in Phase II and beyond will ensure space-qualified, SiC power devices for NASA applications.
- API data.nasa.gov | Last Updated 2018-07-19T13:12:56.000Z
NASA requires innovative guidance, navigation and control (GN&C) technology that addresses the high performance, reliability, power and volume requirements of future Earth Science (ES) missions. Specifically, ES architectures will include platforms of varying size and complexity in a number of mission trajectories and orbits. Novel approaches for autonomous control of large fleets of spacecraft, rockets, balloons and Unmanned Aerial Vehicles (UAVs) are desired. Special interest is apportioned to augmenting and providing alternatives to GN&C, relative range and attitude determination during close formation, and proximity operations using video image processing technology. Broadata Communications, Inc. (BCI) proposes a novel vision-based attitude determination and relative range GN&C system called Guiding Stars, Sun and Light (GSSL). It is based on an innovative, real-time, video image, point distance set based, recognition technology that works well with the problem at hand.
- API data.nasa.gov | Last Updated 2018-07-19T08:57:03.000Z
Model calculations and risk assessment estimates indicate that secondary neutrons, with energies ranging between 0.5 to >150 MeV, make a significant contribution to the total absorbed dose received by space crews during long duration space missions [1-3]. Advanced scintillation materials, which exhibit radiation type and mass dependent emission times, coupled to SSPM detectors, provide the optimum volume to payload performance and the ability to easily discriminate between the fraction of dose, which results from secondary neutrons, and that which results from exposure to energetic charged particles and background gamma-rays. The Phase-1 effort successfully characterized the critical components of the proposed dosimeter, specifically, the response of the scintillation material to irradiation by gamma-rays, protons, and neutrons, as well as the performance of the SSPM detector. The Phase-1 modeling studies provide a critical foundation for assessing the anticipated signals in the space radiation environment. The proposed dosimeter would overcome many of the limitations in the current generation of neutron dosimeters, and would provide baseline information on the physics, needed with the information from biological studies, to assess risk in future human-space-exploration missions to the moon and Mars.
- API data.nasa.gov | Last Updated 2018-07-19T13:15:14.000Z
The objective of this Phase II project is to develop and demonstrate a compact and reliable oscillator technology for the frequency band from 100 ? 250 GHz for use in terahertz local oscillators and transmitters. The new oscillators rely on MMIC technology that is reliable and robust, offers the best overall performance and will be suitable for volume production and commercialization. These oscillators meet immediate needs for NASA's Earth Science program, specifically for terahertz radiometers for studies of the atmosphere and climate change. The oscillators are also useful for a wide range of other scientific, military and emerging commercial applications. The Phase I study demonstrated the feasibility of the new oscillators through the development and demonstration of an oscillator at 146 GHz suitable as a driver for an 874 GHz cloud ice radiometer being developed at NASA/GSFC. This new component greatly exceeds the performance of any other commercially available oscillator technology while maintaining a compact size, power efficiency and all solid-state construction. The Phase II research is focused on achieving greater power for higher frequency terahertz sources, improving power efficiency, achieving more compact integration of the subcomponents and extending the basic design concept throughout the 100 ? 250 GHz band.
- API data.nasa.gov | Last Updated 2018-09-07T17:39:50.000Z
<p style="margin-left:0in; margin-right:0in">Busek proposes to develop a new form of passive electrospray thruster control which will enable extremely fast thruster operations and thereby unprecedented minimum impulse bits. Busek’s BET-300-P thruster is under active development as a precision reaction control system (RCS) which will provide orders of magnitude improvements over state-of-the-art alternative attitude control systems (ACS) for CubeSats and small spacecraft. The low inertia of CubeSats combined with vibrational disturbances and resolution limitations of state-of-the-art ACS presently limit precision body-pointing and position control. Busek’s electrospray thrusters aboard the ESA LISA Pathfinder (NASA ST-7) spacecraft, recently demonstrated control of a proof mass location to within ~2nm per root Hz over a wide band. The BET-300-P, enhanced by exploitation of its high-speed dynamic response in this program, seeks to extend that success to small spacecraft platforms.</p> <p style="margin-left:0in; margin-right:0in">Passively fed electrospray thrusters are highly compact, including fully integrated propellant supplies, and are capable of ~100nN thrust precision with 10’s of nN noise. Thrust can be accurately throttled over >30x, up to a scalable maximum of 10’s to 100’s of uN. While typically operated in largely continuous states they are unique in that emission can be electrically stopped/started at ms time scales. Thus, extremely low impulse bits may be achieved over very short durations, permitting throttling from <0.1uNs up to 100’s of uNs. Realization of this fundamental capability of the technology is presently limited by control circuitry. The proposed work seeks to study and overcome these limitations with a new control methodology.</p> <p>These traits, combined with >800s specific impulse, and thereby low propellant mass could enable these systems to replace traditional reaction wheel ACS and high-propellant mass cold gas systems; enabling milliarcsec control authority for CubeSats versus the present arcsec level SOA.</p>
The Cyogenic Evaluation of Irradiated Composite Materials for Use in Composite Pressure Vessels, Phase Idata.nasa.gov | Last Updated 2018-07-19T13:26:43.000Z
The intent of this proposal is to develop key building block technology for lightweight composite structures suitable for cryogenic fuel depot storage as well as human in-space habitat. The effort will incorporate and expand on previous work by the participants in the cryogenic performance of composite materials as well as improved impact technologies for micro-meteor/space debris survivability. It will then develop radiation resistant capabilities. In order to develop reliable composite structures for use as cryogenic fuel storage, human habitation, or other mission critical application a solid understanding of constituent material environmental capabilities is required. While good progress has been made in expanding the knowledge of how composite fibers and matrix systems (resins) react to loads and strains at extremely cold temperatures little to no effort has been made to incorporate radiation exposure such as would be encountered with in-space fuel storage depots. With a view to developing dual-use lightweight composite structures the proposed effort will develop improved composite material resistance to the harsh radiation environment a spacecraft would be expected to encounter during the life of its mission. Our intent is to develop robust light weight composite structures which are cryogenic capable as well as impact and radiation resistant.