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All sourcesNASA NTRSDOE OSTI
NASA NTRS2013

Advanced Water Purification System for In Situ Resource Utilization

A main goal in the field of In Situ Resource Utilization is to develop technologies that produce oxygen from regolith to provide consumables to an extraterrestrial outpost. The processes developed reduce metal oxides in the regolith to produce water, which is then electrolyzed to produce oxygen. Hydrochloric and hydrofluoric acids are byproducts of the reduction processes, which must be removed to meet electrolysis purity standards. We previously characterized Nation, a highly water selective polymeric proton-exchange membrane, as a filtration material to recover pure water from the contaminated solution. While the membranes successfully removed both acid contaminants, the removal efficiency of and water flow rate through the membranes were not sufficient to produce large volumes of electrolysis-grade water. In the present study, we investigated electrodialysis as a potential acid removal technique. Our studies have shown a rapid and significant reduction in chloride and fluoride concentrations in the feed solution, while generating a relatively small volume of concentrated waste water. Electrodialysis has shown significant promise as the primary separation technique in ISRU water purification processes.

Anthony, Stephen M.↗
NASA NTRS2014

Exfoliation of Hexagonal Boron Nitride via Ferric Chloride Intercalation

Sodium fluoride (NaF) was used as an activation agent to successfully intercalate ferric chloride (FeCl3) into hexagonal boron nitride (hBN). This reaction caused the hBN mass to increase by approx.100 percent, the lattice parameter c to decrease from 6.6585 to between 6.6565 and 6.6569 Ǻ, the x-ray diffraction (XRD) (002) peak to widen from 0.01deg to 0.05deg of the full width half maximum value, the Fourier transform infrared (FTIR) spectrum's broad band (1277/cm peak) to change shape, and new FTIR bands to emerge at 3700 to 2700 and 1600/cm. This indicates hBN's structural and chemical properties are significantly changed. The intercalated product was hygroscopic and interacted with moisture in the air to cause further structural and chemical changes (from XRD and FTIR). During a 24-h hold at room temperature in air with 100 percent relative humidity, the mass increased another 141 percent. The intercalated product, hydrated or not, can be heated to 750 C in air to cause exfoliation. Exfoliation becomes significant after two intercalation-air heating cycles, when 20-nm nanosheets are commonly found. Structural and chemical changes indicated by XRD and FTIR data were nearly reversed after the product was placed in hydrochloric acid (HCl), resulting in purified, exfoliated, thin hBN products.

Hung, Ching-cheh↗
NASA NTRS2014

Advanced Water Purification System for In Situ Resource Utilization Project

A main goal in the field of In Situ Resource Utilization is to develop technologies that produce oxygen from regolith to provide consumables to an extratrrestrial outpost. The processes developed reduce metal oxides in the regolith to produce water, which is then electrolyzed to produce oxygen. Hydrochloric and hydrofluoric acids are byproducts of the reduction processes, which must be removed to meet electrolysis purity standards. We previously characterized Nation, a highly water selective polymeric proton-exchange membrane, as a filtrtion material to recover pure water from the contaminated solution. While the membranes successfully removed both acid contaminants, the removal efficiency of and water flow rate through the membranes were not sufficient to produce large volumes of electrolysis-grade water. In the present study, we investigated electrodialysis as a potential acid removable technique. Our studies have show a rapid and significant reduction in chloride and fluoride concentrations in the feed solution, while generating a relatively small volume of concentrated waste water. Electrodialysis has shown significant promise as the primary separation technique in ISRU water purification processes.

Technology Portfolio System↗
NASA NTRS2013

Materials Combustion Testing and Combustion Product Sensor Evaluations in FY12

NASA Centers continue to collaborate to characterize the chemical species and smoke particles generated by the combustion of current space-rated non-metallic materials including fluoropolymers. This paper describes the results of tests conducted February through September 2012 to identify optimal chemical markers both for augmenting particle-based fire detection methods and for monitoring the post-fire cleanup phase in human spacecraft. These studies follow up on testing conducted in August 2010 and reported at ICES 2011. The tests were conducted at the NASA White Sands Test Facility in a custom glove box designed for burning fractional gram quantities of materials under varying heating profiles. The 623 L chamber was heavily instrumented to quantify organics (gas chromatography/mass spectrometry), inorganics by water extraction followed by ion chromatography, and select species by various individual commercially-available sensors. Evaluating new technologies for measuring carbon monoxide, hydrogen cyanide, hydrogen fluoride, hydrogen chloride and other species of interest was a key objective of the test. Some of these sensors were located inside the glovebox near the fire source to avoid losses through the sampling lines; the rest were located just outside the glovebox. Instruments for smoke particle characterization included a Tapered Element Oscillating Microbalance Personal Dust Monitor (TEOM PDM) and a TSI Dust Trak DRX to measure particle mass concentration, a TSI PTrak for number concentration and a thermal precipitator for collection of particles for microscopic analysis. Materials studied included Nomex(R), M22759 wire insulation, granulated circuit board, polyvinyl chloride (PVC), Polytetrafluoroethylene (PTFE), Kapton(R), and mixtures of PTFE and Kapton(R). Furnace temperatures ranged from 340 to 640 C, focusing on the smoldering regime. Of particular interest in these tests was confirming burn repeatability and production of acid gases with different fuel mixture compositions, as well as the dependence of aerosol concentrations on temperature.

Combustion↗
NASA NTRS2015

DRAGONS-A Micrometeoroid and Orbital Debris Impact Sensor on the ISS

The Debris Resistive/Acoustic Grid Orbital Navy-NASA Sensor (DRAGONS) is intended to be a large area impact sensor for in situ measurements of micrometeoroids and orbital debris (MMOD) in the sub-millimeter to millimeter size regime in the near Earth space environment. These MMOD particles are too small to be detected by ground-based radars and optical telescopes, but still large enough to be a serious threat to human space activities and robotic missions in the low Earth orbit (LEO) region. The nominal detection area of DRAGONS is 1 sq m, consisting of four 0.5 m × 0.5 m independent panels, but the dimensions of the panels can easily be modified to accommodate different payload constraints. The approach of the DRAGONS design is to combine three particle impact detection concepts to maximize information that can be extracted from each detected impact. The first is a resistive grid consisting of 75-micrometer-wide resistive lines, coated in parallel and separated by 75 micrometer gaps on a 25-micrometer thin film. When a particle a few hundred micrometers or larger strikes the grid, it would penetrate the film and sever some resistive lines. The size of the damage area can be estimated from the increased resistance. The second concept is based on polyvinylidene fluoride (PVDF) acoustic impact sensors. Multiple PVDF sensors are attached to the thin film to provide the impact timing information. From the different signal arrival times at different acoustic sensors, the impact location can be calculated via triangulation algorithms. The third concept employs a dual-layer film system where a second 25-micrometer film is placed 15 cm behind the resistive-grid film. Multiple PVDF acoustic sensors are also attached to the second film. The combination of impact timing and location information from the two films allows for direct measurements of the impact direction and speed. The DRAGONS technology development has been funded by several NASA organizations since 2002, first by the NASA Science Mission Directorate and the NASA Exploration Systems Mission Directorate, then by the NASA JSC Innovative Research and Development Program and the NASA Orbital Debris Program Office. The NASA Orbital Debris Program Office leads the effort with collaboration from the U.S. Naval Academy, Naval Research Laboratory, University of Kent at Canterbury in Great Britain, and Virginia Tech. The project recently reached a major milestone when DRAGONS was approved for a technology demonstration mission by the International Space Station (ISS) Program in October 2014. The plan is to deploy a 1 sq m DRAGONS on the ISS with the detection surface facing the ram-direction for 2 to 3 years. The tentative launch schedule is in early 2017. This mission will collect data on orbital debris in the sub-millimeter size regime to better define the small orbital debris environment at the ISS altitude. The mission will also advance the DRAGONS Technology Readiness Level to 9 and greatly enhance the opportunities to deploy DRAGONS on other spacecraft to high LEO orbits in the future.

Liou, J.-C.↗
NASA NTRS2014

Recent Progress on 2012 SAT for UVOIR Coatings

Astronomical observations in the Far Ultraviolet (FUV) spectral region are some of the more challenging due to the very distant and faint objects that are typically searched for in cosmic origin studies such as origin of large scale structure, the formation, evolution, and age of galaxies and the origin of stellar and planetary systems. These challenges are driving the need to improve the performance of optical coatings over a wide spectral range that would increase reflectance in mirrors and reduced absorption in dielectric filters used in optical telescope for FUV observations. This paper will present recent advances in reflectance performance for Al+MgF2 mirrors optimized for Lyman-alpha wavelength by performing the deposition of the MgF2 overcoat at elevated substrate temperatures. We will also present optical characterization of little studied rare-earth fluorides such as GdF3 and LuF3 that exhibit low-absorption over a wide wavelength range and could therefore be used as high refractive index alternatives fordielectric coatings at FUV wavelengths.

LiF↗
NASA NTRS2014

High Temperature Solid Lubricant Coating for High Temperature Wear Applications

A self-lubricating, friction and wear reducing composite useful over a wide temperature range is described herein. The composite includes metal bonded chromium oxide dispersed in a metal binder having a substantial amount of nickel. The composite contains a fluoride of at least one Group I, Group II, or rare earth metal, and optionally a low temperature lubricant metal.

DellaCorte, Christopher↗
NASA NTRS2015

Temperature-Dependent Refractive Index Measurements of Caf2, Suprasil 3001, and S-FTM16 for the Euclid Near Infrared Spectrometer and Photometer

Using the Cryogenic High Accuracy Refraction Measuring System (CHARMS) at NASA's Goddard Space Flight Center, we measured absolute refractive indices at temperatures from 100 to 310 K at wavelengths from 0.42 to 3.6 microns for CaF2, Suprasil 3001 fused silica, and S-FTM16 glass in support of lens designs for the Near Infrared Spectrometer and Photometer (NISP) for ESA's Euclid dark energy mission. We report absolute refractive index, dispersion (dn/dλ), and thermo-optic coefficient (dn/dT) for these materials. In this study, materials from different melts were procured to understand index variability in each material. We provide temperature-dependent Sellmeier coefficients based on our data to allow accurate interpolation of index to other wavelengths and temperatures. For calcium fluoride (CaF2) and S-FTM16, we compare our current measurements with CHARMS measurements of these materials made in the recent past for other programs. We also compare Suprasil 3001's indices to those of other forms of fused silica we have measured in CHARMS.

geometrical optics↗
NASA NTRS1961

Development of Ceramic Fibers for Reinforcement in Composite Materials

Refinements of the vertical arc fiberizing apparatus resulted in its ability to fiberize very different refractory glasses having wide ranges of properties. Although the apparatus, was originally designed as a laboratory research tool for the evaluation of many compositions daily, up to one quarter pound of fibers of a single composition could be produced in an 8-hour day. Fibers up to six and a half feet long were produced with the apparatus. Studies were conducted of two methods of fiberizing refractory glasses requiring rapid freezing from the melt. The first method consisted of fiberizing droplets of molten glass passing through an annular nozzle. The second method consisted of reconstructing the annular nozzle in. the shape of a horseshoe to achieve a shorter delay in blasting a molten droplet from the tip of a rod. Both methods were judged feasible for producing fibers of glasses requiring rapid freezing. The first method would be more amenable to volume fiber production. Studies of induction heating for fiber formation did not lead to its designation as a very efficient heating method. Problems. remain to be solved, in the design of a suitable susceptor for a higher heating rate, in protecting the susceptor from oxidation with an inert gas, in contamination of the melt from a refractory crucible, and in the protective radiation shielding of the induction concentrator coil. It is not considered practical to continue studies of this heating method. In the course of this program 151 refractory glass compositions were evaluated for fiber, forming characteristics. Of the various types of materials studied, the following showed promise in producing acceptable refractory fibers: sIlica- spinel (magnesium aluminate), silica- spinel-zirconia, silica-zirconia, silica-zinc spinel, aluminum phosphate glasses, and fluoride glasses. Compositions which did not produce acceptable fibers were high zirconia materials, barium spinels, and calcium aluminates. Improvements in the. testing apparatus for single fiber tensile strength increased the precision. of tests conducted on nine fibers. The highest mean tensile strength, a value of 295,000 pounds per square inch, was obtained with R-141 fibers. Treatment of R-74 fibers with anhydrous Linde A-1100 silane finish improved its mean fiber tensile strength by 25 percent. The lapse of time after fiber formation had no measurable effect on tensile strength. A static heating test conducted with various high melting fibers indicated that Fiberfrax and R-108 underwent no significant changes in bulk volume or resiliency on exposure to 2750 degrees Fahrenheit (1510 degrees Centigrade) in an oxidizing atmosphere. For fiber-resin composition fabrication, ten fiber materials were selected on the bases of high fiber yield, fusion temperature, and type of composition. Fiberfrax, a commercial ceramic fiber, was included for comparison. A new, more effective method of removing pellets from blown fibers was developed. The de-pelletized fibers were treated with a silane finish and felted into ten-inch diameter felts prior to resin impregnation. Composites containing 30 percent by weight of CTL 91-LD phenolic resin were molded under high pressure from the impregnated felts and post-cured to achieve optimum properties. Flexural strength, flexural modules of elasticity, and punch shear strength tests were conducted on the composite specimens. The highest average flexural strength obtained was 19,958 pounds per square inch with the R-74-fiber-resin composite. This compares very favorably with the military specification of 13,000 pounds per square inch flexural strength for randomly oriented fiber reinforced composites. The highest punch shear strength (11,509 pounds per square inch) was obtained with the R-89 fiber-resin composite. The effects of anhydrous fiber finishes on composite strength were not clearly indicated. Plasma arc tests at a heat flux of 550 British Thermal Units per square foot per second on eight composite materials indicated ablation rates generally equivalent to Fiberglas-Micarta No. 259-2. The composite reinforced with R-99 fibers had an average ablation rate of 0.008 inch per second and appears quite promising on the basis of these tests. Preliminary studies for processing fibers into yarn and fabric were conducted with R-99 fibers. The use of certain organic gums aided in 2 fabricating by hand several relatively strong yarns and a crude fabric swatch. This indicated the practicality of developing techniques for processing these fibers into yarn and fabric without significant damage to the fibers.

Gates, L. E.↗
NASA NTRS2015

High-Reflectivity Multi-Layer Coatings for the CLASP Sounding Rocket Project

We are planning an international rocket experiment Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is (2015 planned) that Lyman alpha line (Ly alpha line) polarization spectroscopic observations from the sun. The purpose of this experiment, detected with high accuracy of the linear polarization of the Ly alpha lines to 0.1% by using a Hanle effect is to measure the magnetic field of the chromosphere-transition layer directly. For polarization photometric accuracy achieved that approximately 0.1% required for CLASP, it is necessary to realize the monitoring device with a high throughput. On the other hand, Ly alpha line (vacuum ultraviolet rays) have a sensitive characteristics that is absorbed by the material. We therefore set the optical system of the reflection system (transmission only the wavelength plate), each of the mirrors, subjected to high efficiency of the multilayer coating in accordance with the role. Primary mirror diameter of CLASP is about 30 cm, the amount of heat about 30,000 J is about 5 minutes of observation time is coming mainly in the visible light to the telescope. In addition, total flux of the sun visible light overwhelmingly large and about 200 000 times the Ly alpha line wavelength region. Therefore, in terms of thermal management and 0.1% of the photometric measurement accuracy achieved telescope, elimination of the visible light is essential. We therefore, has a high reflectivity (greater than 50%) in Ly alpha line, visible light is a multilayer coating be kept to a low reflectance (less than 5%) (cold mirror coating) was applied to the primary mirror. On the other hand, the efficiency of the polarization analyzer required chromospheric magnetic field measurement (the amount of light) Conventional (magnesium fluoride has long been known as a material for vacuum ultraviolet (MgF2) manufactured ellipsometer; Rs = 22%) about increased to 2.5 times were high efficiency reflective polarizing element analysis. This device, Bridou et al. (2011) is proposed "that is coated with a thin film of the substrate MgF2 and SiO2 fused silica." As a result of the measurement, Rs = 54.5%, to achieve a Rp = 0.3%, high efficiency, of course, capable of taking out only about spolarized light. Other reflective optical elements (the secondary mirror, the diffraction grating-collector mirror), subjected to high-reflection coating of Al + MgF2 (reflectance of about 80%), less than 5% in the entire optical system by these (CCD Science was achieved a high throughput as a device for a vacuum ultraviolet ray of the entire system less than 5% (CCD of QE is not included).

sounding rocket↗
NASA NTRS2016

Optical Evaluation of DMDs with UV-Grade FS, Sapphire, MgF2 Windows and Reflectance of Bare Devices

Digital Micro-mirror Devices (DMDs) have been identified as an alternative to microshutter arrays for space-based multi-object spectrometers (MOS). Specifically, the MOS at the heart of a proposed Galactic Evolution Spectroscopic Explorer (GESE) that uses the DMD as a reprogrammable slit mask. Unfortunately, the protective borosilicate windows limit the use of DMDs in the UV and IR regimes, where the glass has insufficient throughput. In this work, we present our efforts to replace standard DMD windows with custom windows made from UV-grade fused silica, Low Absorption Optical Sapphire (LAOS) and magnesium fluoride. We present reflectance measurements of the antireflection coated windows and a reflectance study of the DMDs active area (window removed). Furthermore, we investigated the long-term stability of the DMD reflectance and recoating device with fresh Al coatings.

Quijada, Manuel A.↗
NASA NTRS2015

Multifunctional Electroactive Nanocomposites Based on Piezoelectric Boron Nitride Nanotubes

Space exploration missions require sensors and devices capable of stable operation in harsh environments such as those that include high thermal fluctuation, atomic oxygen, and high-energy ionizing radiation. However, conventional or state-of-the-art electroactive materials like lead zirconate titanate, poly(vinylidene fluoride), and carbon nanotube (CNT)-doped polyimides have limitations on use in those extreme applications. Theoretical studies have shown that boron nitride nanotubes (BNNTs) have strength-to-weight ratios comparable to those of CNTs, excellent high-temperature stability (to 800 C in air), large electroactive characteristics, and excellent neutron radiation shielding capability. In this study, we demonstrated the experimental electroactive characteristics of BNNTs in novel multifunctional electroactive nanocomposites. Upon application of an external electric field, the 2 wt % BNNT/polyimide composite was found to exhibit electroactive strain composed of a superposition of linear piezoelectric and nonlinear electrostrictive components. When the BNNTs were aligned by stretching the 2 wt % BNNT/polyimide composite, electroactive characteristics increased by about 460% compared to the nonstretched sample. An all-nanotube actuator consisting of a BNNT buckypaper layer between two single-walled carbon nanotube buck-paper electrode layers was found to have much larger electroactive properties. The additional neutron radiation shielding properties and ultraviolet/visible/near-infrared optical properties of the BNNT composites make them excellent candidates for use in the extreme environments of space missions. utilizing the unique characteristics of BNNTs.

Kang, Jin Ho↗
NASA NTRS2016

Erosion Data from the MISSE 8 Polymers Experiment After 2 Years of Space Exposure on the International Space Station

The Polymers Experiment was exposed to the low Earth orbit (LEO) space environment for 2.14 and 2.0 years as part of the Materials International Space Station Experiment 8 (MISSE 8) and the Optical Reflector Materials Experiment-III (ORMatE-III), respectively. The experiment contained 42 samples, which were flown in either ram, wake, or zenith orientations. The primary objective was to determine the effect of solar exposure on the atomic oxygen erosion yield (Ey) of fluoropolymers. This paper provides an overview of the experiment with details on the polymers flown, the characterization techniques used, the atomic oxygen fluence for each exposure orientation, and the LEO Ey results. The Ey values for the fluoropolymers range from 1.45 x 10(exp -25) cm(exp 3)/atom for white Tedlar Registered Trademark (polyvinyl fluoride with white titanium dioxide pigment) flown in the ram orientation to 6.32 x 10(exp -24) cm(exp 3)/atom for aluminized-Teflon Registered Trademark fluorinated ethylene propylene (Al-FEP) flown in the zenith orientation. Erosion yield data for FEP flown in ram, wake and zenith orientations are compared, and the Ey was found to be highly dependent on orientation, hence environmental exposure. Teflon FEP had an order of magnitude higher Ey when flown in the zenith direction (6.32 x10(exp -24) cm(exp3)/atom) as compared to the ram direction (2.37 x 10(exp -25) cm(exp 3)/atom). The Ey of FEP was found to increase with a direct correlation to the solar exposure/AO fluence ratio showing the effect of solar radiation and/or heating due to solar exposure on FEP erosion. In addition, back-surface carbon painted FEP (C-FEP) flown in the zenith orientation had a significantly higher Ey than clear FEP or Al-FEP further indicating that heating has a significant impact on the erosion of FEP, particularly in the zenith orientation.

Solar radiation↗
NASA NTRS2015

Solar Lyman-Alpha Polarization Observation of the Chromosphere and Transition Region by the Sounding Rocket Experiment CLASP

We are planning an international rocket experiment Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is (2015 planned) that Lyman α line (Ly(alpha) line) polarization spectroscopic observations from the sun. The purpose of this experiment, detected with high accuracy of the linear polarization of the Ly(alpha) lines to 0.1% by using a Hanle effect is to measure the magnetic field of the chromosphere-transition layer directly. For polarization photometric accuracy achieved that approx. 0.1% required for CLASP, it is necessary to realize the monitoring device with a high throughput. On the other hand, Ly(alpha) line (vacuum ultraviolet rays) have a sensitive characteristics that is absorbed by the material. We therefore set the optical system of the reflection system (transmission only the wavelength plate), each of the mirrors, subjected to high efficiency of the multilayer coating in accordance with the role. Primary mirror diameter of CLASP is about 30 cm, the amount of heat about 30,000 J is about 5 minutes of observation time is coming mainly in the visible light to the telescope. In addition, total flux of the sun visible light overwhelmingly large and about 200 000 times the Ly(alpha) line wavelength region. Therefore, in terms of thermal management and 0.1% of the photometric measurement accuracy achieved telescope, elimination of the visible light is essential. We therefore, has a high reflectivity (> 50%) in Lyα line, visible light is a multilayer coating be kept to a low reflectance (<5%) (cold mirror coating) was applied to the primary mirror. On the other hand, the efficiency of the polarization analyzer required chromospheric magnetic field measurement (the amount of light) Conventional (magnesium fluoride has long been known as a material for vacuum ultraviolet (MgF2) manufactured ellipsometer; Rs = 22%) about increased to 2.5 times were high efficiency reflective polarizing element analysis. This device, Bridou et al. (2011) is proposed "that is coated with a thin film of the substrate MgF2 and SiO2 fused silica." As a result of the measurement, Rs = 54.5%, to achieve a Rp = 0.3%, high efficiency, of course, capable of taking out only about s-polarized light. Other reflective optical elements (the secondary mirror, the diffraction gratingcollector mirror), subjected to high-reflection coating of Al + MgF2 (reflectance of about 80%), less than 5% in the entire optical system by these (CCD Science was achieved a high throughput as a device for a vacuum ultraviolet ray of the entire system less than 5% (CCD of QE is not included).

Narukage, Noriyuki↗
NASA NTRS2016

Laboratory Testing and Performance Verification of the CHARIS Integral Field Spectrograph

The Coronagraphic High Angular Resolution Imaging Spectrograph (CHARIS) is an integral field spectrograph (IFS) that has been built for the Subaru telescope. CHARIS has two imaging modes; the high-resolution mode is R82, R69, and R82 in J, H, and K bands respectively while the low-resolution discovery mode uses a second low-resolution prism with R19 spanning 1.15-2.37 microns (J+H+K bands). The discovery mode is meant to augment the low inner working angle of the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) adaptive optics system, which feeds CHARIS a coronagraphic image. The goal is to detect and characterize brown dwarfs and hot Jovian planets down to contrasts five orders of magnitude dimmer than their parent star at an inner working angle as low as 80 milliarcseconds. CHARIS constrains spectral crosstalk through several key aspects of the optical design. Additionally, the repeatability of alignment of certain optical components is critical to the calibrations required for the data pipeline. Specifically the relative alignment of the lens let array, prism, and detector must be highly stable and repeatable between imaging modes. We report on the measured repeatability and stability of these mechanisms, measurements of spectral crosstalk in the instrument, and the propagation of these errors through the data pipeline. Another key design feature of CHARIS is the prism, which pairs Barium Fluoride with Ohara L-BBH2 high index glass. The dispersion of the prism is significantly more uniform than other glass choices, and the CHARIS prisms represent the first NIR astronomical instrument that uses L-BBH2as the high index material. This material choice was key to the utility of the discovery mode, so significant efforts were put into cryogenic characterization of the material. The final performance of the prism assemblies in their operating environment is described in detail. The spectrograph is going through final alignment, cryogenic cycling, and is being delivered to the Subaru telescope in April 2016. This paper is a report on the laboratory performance of the spectrograph, and its current status in the commissioning process so that observers will better understand the instrument capabilities. We will also discuss the lessons learned during the testing process and their impact on future high-contrast imaging spectrographs for wavefront control.

Coronagraphic High Angular Resolution Imaging Spec↗
NASA NTRS2016

Analysis of a Radioisotope Thermal Rocket Engine

The Triton Hopper is a concept for a global hopper vehicle which uses a radioisotope rocket engine and In-situ propellant acquisition to explore the surface of Neptune's moon, Triton. The current Triton Hopper concept stores heated Nitrogen in a spherical tank to be used as the propellant. The aim of the research was to investigate the benefits of storing propellant at ambient temperature and heating it through the use of a thermal block during engine operation, as opposed to storing gas at a high temperature. Lithium, Lithium Fluoride and Beryllium were considered as possible materials for the thermal block. A heat energy analysis indicated that a lithium thermal mass would provide the highest heat energy for a temperature change from 900 Celsius to -100 Celsius. A heat transfer analysis was performed for Nitrogen at -100 Celsius flowing through 1000 passages inside a 1kg lithium thermal block at a temperature of 900 Celsius. The system was analyzed as turbulent flow through a tube with constant surface temperature. The analysis indicated that the propellant reached a maximum temperature of 877 Celsius before entering the nozzle. At this exit temperature, the average specific impulse [I(sub sp)] of the engine was determined to be 157s. Previous studies for the stored heated gas concept suggest that the engine would have an average I(sub sp) of approximately 52s. Thus, the use of a thermal block concept results in a 200 percent engine performance increase. In addition, a tank sizing study was performed to determine if the concept is feasible in terms of mass requirements. The mass for a spherical carbon fiber COPV storing 35kg of nitrogen at an initial temperature of -100 Celsius and a pressure of 1000psia, was determined to be 7.2kg. The specific impulse analysis indicated that the maximum engine performance is obtained for a mass ratio of 5kg of Nitrogen per every 1kg of lithium thermal mass. Thus for 35kg of Nitrogen the total thermal mass would be 7kg. This brings the total mass of the system to 49.2.kg which is less than the 56kg landing payload capacity of the Triton Hopper. Finally, an insulation analysis using 10mm of MLI insulation indicated that a total of 22 watts of heat are lost to the environment. With the heat loss known, the power required to heat the thermal mass to 900 Celsius in 24 days was determined to be 2.15 watts. The study's results allowed us to conclude that the thermal mass concept is the better option due to the performance increase provided, the low power requirement and its compliance with the landing mass requirement of the Triton Hopper.

Radioisotope↗
NASA NTRS2018

Surface Modification at Nanoscale; Nanoparticle-Nanowire Transition

Binary, ternary and quaternary oxides and selenides have been developed and used in multiple applications including high power lasers, detectors, dielectric energy storage and variety of optical devices. These materials have been grown by Bridgman, physical vapor transport (PVT), chemical vapor transport (CVT) methods and flux methods in the form of bulk thin film, nanocrystals and nanowires. With increasing thrust of bio applications, nanoparticles it is essential to understand nucleation and nanomorphological transition during drug delivery, growth of nanoengineered bio composites in body, grain growth and final morphology. Addition of fluorides and selenides have increased significantly in synthetic tissue constituents because of some advantages in adhesion and stability. We have performed experiments on multinary oxides Sr-Ba-O-F, Se-Tl-As and Se-Pb-Sn-Se using several growth methods to demonstrate nanoparticle and nanowire transition. This study has great potential to increase surface area and also provides understanding to the mechanism of nanowire growth.

Singh, N. B.↗
NASA NTRS2018

Electrostatic Levitation of ZBLAN and Chalcogenide Glasses

Heavy Metal Fluoride Glasses have been studied for approximately 35 years. ZrF4-BaF BaF2-LaF3-AlF3-NaF (ZBLAN) showed the most promise as an optical fiber. It transmits IR out to approximately 5 microns. Applications: fiber amplifiers, lasers and nuclear radiation resistant links. Intrinsic and Extrinsic processes limit light propagation; Intrinsic: band gap absorption, Rayleigh scatter and multiphonon absorption; Extrinsic: impurities such as rare-earth ions and crystallite formation. Theoretical loss coefficient is 0.001 dB/km. This loss has not been achieved to date due to intrinsic and extrinsic processes. ZBLAN fibers obtained from Infrared Focal Systems, Inc. and Bell Laboratories. Fibers were stripped of coating and placed in evacuated quartz ampoules. These fibers were first flown on NASA’s KC135 Reduced Gravity Aircraft. KC135 produces approximately 25 sec. of reduced gravity per parabola. One week of flights led to approximately 200 total parabolas. Fibers were heated to the crystallization temperature during reduced gravity and compared to unit gravity for the same amount of time. Fibers were also flown on board the Conquest sub-orbital rocket. This flight gave approximately 6.5 minutes of reduced gravity.

Tucker, Dennis S.↗