- API data.nasa.gov | Last Updated 2018-07-19T10:56:16.000Z
CRICKET will employ a novel mobility concept to explore permanently shadowed regions (PSR) on the Moon. The volatiles stored in lunar polar areas and on other bodies are important not only for science, but also for exploration in the context of in situ resource utilization (ISRU). CRICKET considers different architectures for simple, relatively inexpensive robots operating as members of a hive to explore PSR, locate areas where water ice is at or near the surface, and relays this information to Earth. CRICKET considers various approaches to moving about on the surface in this biomimetic approach: crawlers, hoppers, and small soccer-ball style buckey-bot concept in which several of the faces act as pads to propel the bot across the surface. In the APL Buckbot, one face is equipped with sensors to search for the presence of water and other volatiles as both free compounds and bound species. The CRICKET concept consists of three elements, each kept as simple as possible: an orbiter (the "queen" for delivery, location, and communication), a carrier (the "hive" for data collection, navigation, power, and dispersal on the surface), and the “crickets.” Each element is a reasonable extrapolation of existing cubesat and/or commercial technology. Each cricket carries a tiny SWIR and Far UV MEMS spectrograph, Xenon lamp, heating element “proboscis” and “whiskers” for characterizing the volatiles. We use multiple crickets to achieve a high-resolution map and to mitigate risk of failure.
Integrated SiC Super Junction Transistor-Diode Devices for High-Power Motor Control ModulesOoperating at 500 C, Phase Idata.nasa.gov | Last Updated 2018-07-19T11:07:58.000Z
Monolithic Integrated SiC Super Junction Transistor-JBS diode (MIDSJT) devices are used to construct 500<sup>o</sup>C capable motor control power modules for direct integration with the exploration rovers required to operate in Venus-like environments. The Phase I of this proposed work will focus on the integrated MIDSJT device development and high-temperature packaging. Phase II will focus on the integration of the MIDSJT devices to construct full 3-Phase Inverter Motor Control Modules. Although SiC is the semiconductor material of choice for fabricating high-temperature (> 150 <sup>o</sup> C) power electronics, existing SiC MOSFET and JFET based transistor device technologies perform poorly at temperatures exceeding 200 <sup>o</sup> C. The proposed gate oxide-free Integrated MIDSJT device technology will overcome several problems associated with existing SiC device technologies by: (A) exhibiting desirable normally-OFF operation yet best-in-class on-state characteristics at temperatures as high as 500 <sup>o</sup> C, (B) eliminating parasitic inductances/capacitances associated with interconnecting discrete devices, and (C) eliminating high-temperature gate oxide reliability issues. Special device designs and fabrication processes will be investigated in this work for reliable device operation at 500 <sup>o</sup> C. Novel power device packaging techniques in the areas of power substrate, die-attach, chip metallization and wire bonds will be explored to demonstrate reliable module operation at 500 <sup>o</sup> C after several thermal cycles.
- API data.nasa.gov | Last Updated 2018-07-20T05:44:39.000Z
The Phase I Project demonstrated the capability of the Pyrowave? manufacturing process to produce fiber-reinforced ceramics (FRCs) with integral metal features, such as attachment lugs or tubes. In addition, the Phase I Project demonstrated the utility of thermography as a simple, rapid, and inexpensive inspection tool. With the increased emphasis on the exploration of space, technologies supporting fission-powered spacecraft, such as those under development through Project Prometheus, will become increasingly important. For the Phase II Project, Thor Technologies, Inc. will team with Los Alamos National Laboratory (LANL), a computational design firm, a small NDE firm, and a major spacecraft OEM to design, manufacture, and deliver a prototype lightweight, high performance thermal radiator component for fission powered spacecraft, such as the Jupiter Icy Moons Orbiter. The project team has the experience and capability to execute the proposed development plan within the Phase II budget and schedule. The proposed technology will simplify the design and facilitate the utilization of fission-powered, which are essential to the exploration celestial bodies more distant from the Sun than Mars.
Validation of the NSBRI Astronaut Cardiovascular Health and Risk Modification (ASTRO-CHARM) Integrated Cardiovascular Risk Calculatordata.nasa.gov | Last Updated 2018-09-05T23:04:16.000Z
In 2012, the National Space Biomedical Research Institute (NSBRI) supported the development of an integrated tool, termed the Astronaut Cardiovascular Health and Risk Modification (ASTRO-CHARM) Integrated Cardiovascular Risk Calculator. The initial version of this tool was delivered to NSBRI in February of 2014 and has already been implemented in spaceflight on an ad hoc basis. This project seeks to update and validate the ASTRO-CHARM calculator. <p></p> Specific Aim 1: To refine the ASTROCHARM tool using extended cardiovascular (CV) event data. Version 1 of the ASTROCHARM tool comprised 6782 subjects with a 159 CV events over a mean follow up of 7.5 years. Both the Dallas Heart Study (DHS) and Multiethnic Study of Atherosclerosis (MESA) have now extended their CV event follow up to 10 years. Given the younger age of the cohort and resultant lower event rates, enhancing the endpoint numbers will provide more stability and accuracy for the updated risk score model (ASTRO-CHARM version 2.0). <p></p> Specific Aim 2: To validate the ASTROCHARM tool using the Framingham Heart Study coronary artery calcium (CAC) cohort. The ASTRO-CHARM tool demonstrated robust measures of internal validity when assessed in the original combined cohort. These included accurate event rate calibration, as well as improvement in the c-statistic and clinical risk reclassification compared with traditional risk factors alone. However, external validation in another cohort is essential before broader implementation. The Framingham Heart Study (FHS) is the highly regarded original large U.S.-based population-based cohort, where CV risk scores originated. A cohort of the FHS underwent CAC scanning including 2740 subjects <65 years of age, with a mean 8 years of CV event follow up data, and is an ideal study in which to validate the ASTRO-CHARM model. <p></p> Specific Aim 3: To develop a mobile device application to facilitate broad implementation of the ASTRO-CHARM tool. The near universal availability of mobile technologies has enabled broader use of more sophisticated risk scores. Prior versions such as the Framingham Risk Score initially used tabular formats and adding of integer points, and were infrequently utilized in clinical practice. The Pooled Cohort Equation as part of the New 2013 ACC/AHA (American College of Cardiology/American Heart Association) Cholesterol Guidelines has witnessed brisk uptake of a more complex algorithm, partly due to a well-received mobile app that has witnessed more than 64,000 downloads in its first two months.Once validated, a similar tool developed for the ASTROCHARM will greatly enhance its clinical impact. <p></p> ASTROCHARM Version 2. The investigators have extended endpoint data to include another 145 events (304 total), with a median follow up of 10.9 years. They have used these expanded endpoints to refine the ASTRO-CHARM calculator and assessed measures of internal validity of the new calculator including discrimination and calibration which were all robust. They applied the ASTRO-CHARM model to the Framingham Heart Study CAC cohort (n=2057). The ASTRO-CHARM calculator showed good discrimination (c-statistic 0.79) and calibration (Goodness-of-Fit Chi-square: 13.2, p=0.16) in the Framingham study. The authors developed a prototype iPhone app for the ASTRO-CHARM and demonstrated this tool to NASA/NSBRI in late July of 2016. They are preparing the manuscript for scientific publication and the app for broad dissemination for NASA/NSBRI and terrestrial medicine applications. <p></p>
- API data.nasa.gov | Last Updated 2018-09-05T23:07:30.000Z
OBJECTIVES: A major challenge for infrared remote sensing instruments of cold outer solar system targets is simultaneously detecting surface composition as well as surface temperatures. For cold targets <200K, the weak solar insolation results in thermal emission being in the far-IR. Given compositional signature are sensed in mid-IR, the science instrument needs a broad spectral grasp extending to the far-IR. The instrument development proposed here will determine surface composition and temperature of cold targets by using two focal planes to measure simultaneously both the mid- and far-IR. The objective of the proposal is to develop to TRL 3 a versatile infrared imaging spectrometer, spanning the spectral wavelength range 7 to 50 µm, with spectroscopic measurements in the 7-14 µm range and radiometric band measurements spanning 7-50 µm. This instrument is ideal for missions to airless bodies, including but not limited to Triton on a future Neptune Flagship-class mission, Trojan Asteroids, Enceladus or Io New Frontiers class missions. This instrument will build on substantial existing heritage and investments at GSFC, including the Voyager IRIS, Cassini CIRS, and recently a Thermal IMager for Europa Reconnaissance and Science (TIMERS) concept developed under Instrument Concepts for Europa Exploration (ICEE). The proposed instrument development will provide NASA a cold target optimized thermal imaging spectrometer to study cryovolcanism, heat flow, composition, and terrain. The innovative dual-focal plane design provides simultaneous mapping at mid and far IR wavelengths. The baseline design uses a custom 4-line 32 thermopile pixel array and a 384x288 pixel microbolometer array. The instrument has the capability to resolve temperature contrast to an accuracy of better than or equal to 2 K for surface temperatures greater than 70 K. The instrument can also provide 7-14 µm spectra of the surface with a spectral resolution of 200-350. METHODOLOGY: The thermal imaging spectrometer proposed here will build on substantial work that has already been done at GSFC on thermal instruments. In particular, this proposal will develop the key measurement concept namely the thermopile focal plane, which measures thermal radiation with multiple channels from 7-50 µm and allows some light to pass into a optical backend that measures the spectra from 7-14 µm. This backend consists of an Offner spectrometer that incorporates a grating and images a slit onto a microblomter array. Designed for pushbroom operation, the spacecraft velocity will be used to map the surface. The project has a work plan to develop the instrument over 3 years to TRL 3. We will begin with optical, mechanical and focal plane subsystem development, and finish with fabrication of key components to demonstrate key elements and provide a proof of concept of instrument capabilities. RELEVANCE: The proposed instrument development project responds directly to the PICASSO goal “to conduct planetary and astrobiology science instrument feasibility studies, concept formation, proof of concept instruments, and advanced component technology development.” The specific missions that we are targeting are a Flagship-class mission – currently under study by the Ice Giants Science Definition Team – and also New Frontiers missions to Io, Enceladus and Trojan asteroids. We will achieve this goal through development of a proof of concept prototype. Through infrared thermal mapping of planetary surfaces, this instrument will directly address science questions raised in the 2013 Decadal Survey for Planetary Sciences.
Development of Wavelet Stochastic Estimation for Identifying the Contribution of Turbulent Structures to the Sound Field of Shear Flows, Phase Idata.nasa.gov | Last Updated 2018-07-20T07:04:16.000Z
Fundamental understanding of noise generation and the development of noise reduction technology requires the development of tools that can analyze simultaneously the relationship between the turbulent flow field and the pressure field both near and far. In this proposal we will demonstrate how Wavelet Stochastic Estimation (WSE) is the most optimal method for correlating the source region to the sound field when using a microphone array and Particle Image Velocimetry. WSE first transforms the far-field pressure signal into the wavelet domain which then enables both temporal and frequency information to be correlated with the flow field. By adding the frequency information to the correlations, it becomes easier to extract the contribution from the large-scale structures and thus relate their dynamics to noise generation. We also demonstrate how WSE can be used with flow structure identification methods, such as the Proper Orthogonal Decomposition (POD), to further improve the link between the sound field and the turbulent flow field. The proposed technology supports the Fundamental Aeronautics Program by improving noise prediction and measurement methods. The technology will be available for both subsonic and supersonic vehicles, with particular emphasis on noise sources generated from shear flows.
- API data.nasa.gov | Last Updated 2018-07-19T07:53:06.000Z
This project will further development of a thruster capable of both chemical monopropellant and electrospray propulsion using a single "green" ionic liquid propellant. the thruster concept consists of an integrated microtube/electrospray thruster that shares all propulsion system hardware between electric and chemical thruster modes, i.e. one propellant, one propellant tank, one feed system, and one thruster. Thus, the thruster is not significantly more massive than a standalone state-of-the-art chemical or electric thruster, but capable of either thrust mode and selectable as mission needs arise. This has several benefits, including the optimization of trajectories using both chemical and electric thrust manuevers as well as a significantly increased mission design space for a single propulsion unit. The propulsion system is capable of both high impulse per unit volume and high thrust per unit volume as the total impulse per unit volume is 1500 N-s/U in the chemical thrust mode and 2750 N-s/U in the electric thrust mode, where either type of manuever could be selected on-the-fly. The specific objectives for this study are to build a single microtube setup and feed system and test both the chemical monopropellant mode and electrospray mode with the same setup. This setup will allow verification of thruster models stemming from previous chemical mode tests, verify electrospray operation at lower flow rates than we have previously tested, and study the interactions in switching from the chemical mode to the electric mode and vice-versa with specific attention paid to potential life limiting mechanisms. As an additional part of this contract, we will work in parallel to investigate techniques required to manufacture multi-emitter arrays and conduct fluid flow and electrostatic simulations to further develop the preliminary thruster design.
- API data.nasa.gov | Last Updated 2018-07-19T04:42:23.000Z
The Lunar Prospector merged telemetry data set is a result of comparing the two Lunar Prospector telemetry data streams and selecting one of them. The Lunar Prospector raw telemetry data downlink stream contains data transmitted in real-time and data that was collected about 50 minutes prior and stored on the spacecraft. The merged telemetry data set contains raw science and instrument engineering data acquired by all of the science instruments (Gamma Ray, Neutron, and Alpha Particle Spectrometers, and the Magnetometer and Electron Reflectometer), along with spacecraft engineering data.
- API data.nasa.gov | Last Updated 2018-07-19T08:14:52.000Z
Present and future NASA missions, including the Asteroid Redirect Mission and efficient cargo delivery to mars, require a substantial increase in lifetime for ion engines and Hall thrusters. This has led to the development of long-life lanthanum hexaboride (LaB6) hollow cathode emitters, which operate at temperatures >1600⁰C. Current state-of-the-art co-axial swaged cathode heaters use magnesium oxide (MgO) insulators, which experience a significant drop in insulation resistance at temperatures of 1300⁰C, causing heater failure. Hollow cathode failure caused by the failure of an external cathode heater is the single most critical event that controls the thruster lifetime. While alumina (Al2O3) has recently been used as a replacement insulator material, it has questionable reliability due to grain growth and void formation at temperatures >1600⁰C. In Phase I, we will formulate a new ceramic insulator using sound scientific principles, and develop a long-life cathode heater that can operate reliably at high power levels (>200 W) at high temperatures greater than 1600⁰C for use in long duration space propulsion missions. We will design, fabricate and test prototype swaged coaxial heaters to demonstrate the superior performance of the new insulators.
- API data.nasa.gov | Last Updated 2018-09-07T17:42:12.000Z
<p>A new class of solid-state, high-performance cryogenic coolers is proposed for space-based applications. Traditionally, cryocoolers for such applications have been Stirling or pulse tube refrigerators. These cryocoolers, although effective, are heavy, bulky, inefficient, and may cause vibrations. A high-performance solid-state cryocooler based on thermomagnetic cooling via the Ettingshausen effect can be lighter, smaller, vibration free, and use less power than the alternatives. Historically, the practical development of the Ettingshausen coolers was discouraged as they required a magnetic field difficult to reach by traditional ferrite magnets. However, recent rare-earth permanent magnets can produce the required field reliably. We propose an Ettingshausen cooler consisting of advanced permanent magnets combined with a novel semiconductor heterostructure predicted to significantly enhance the efficiency of the solid-state cryogenic cooling in a compact size. The Phase I work will demonstrate the preliminary materials properties and the design required to achieve cooling power larger than 0.2‑0.3 W in 30-35 K temperatures ranges for the rejection temperature of 150 K, while consuming less than 5 W power. The grown heterostructure in phase I will be utilized for the manufacturing of a high-efficiency Ettingshausen thermomagnetic cryocooler in Phase II for specific applications in SmallSat or other micro platforms.</p>