The search for organic compounds in various Apollo 12 samples by mass spectrometry
Apollo 12 lunar surface samples analysis for organic compounds by mass spectroscopy and pyrolysis-gas chromatography
Biemann, K.↗
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Microbial assay of lunar samples
Microbial assay of lunar core and surface samples obtained from Apollo 11 and 12 flights
Ellis, W.↗
Mars sample return through parking orbit
A Mars surface sample return mission using Mars direct entry and Mars parking orbit return is described. The mission is designed for a minimum energy requirement and is relatively simple in comparison to the alternative Mars orbital rendezvous mode. The design calls for minimal science, and uses a single Titan IIIE/Centaur launch vehicle. The primary science areas included are biology, biochemistry, geochemistry, and petrology, for detecting life, age dating, and determining chemical compositions and rock types. The total minimum sample requirement would be 30 g. Sampling conditions and recommended measurements are discussed. Maximum use of hardware and experience from the Mariner, Pioneer, and Viking missions is contemplated. The profile for a 1979 conjunction-class mission would include a total time of 1025 days, including one year in Mars parking orbit after sampling. The lander structure, components, and recovery alternatives are explained.
Weaver, W. L.↗
Enhanced spot preparation for liquid extractive sampling and analysis
A method for performing surface sampling of an analyte, includes the step of placing the analyte on a stage with a material in molar excess to the analyte, such that analyte-analyte interactions are prevented and the analyte can be solubilized for further analysis. The material can be a matrix material that is mixed with the analyte. The material can be provided on a sample support. The analyte can then be contacted with a solvent to extract the analyte for further processing, such as by electrospray mass spectrometry.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Some Anticipated Science Results from "Local" Martian Sampling Site(s)
Current planning for return of a surface sample of Mars planned. Scientific aims and more detailed objectives relating to (a) past/extant life, (b) surface processes and interactions, (c) planetary evolution, and (d) human exploration are summarized in the Mars Exploration Program Analysis Group (MPEAG) document. Here we consider how these aims and objectives might be addressed by samples from individual "local" area(s) (diameter < approx 1 km) based on experience with analyzing subsamples of Martian meteorites.
Nyquist, L. E.↗
Corrosion characteristics of Mo and TZM alloy for plasma facing components in molten lithium at 623 K
Here, in this study, the corrosion behaviours of molybdenum (Mo) and a Mo-based alloy (TZM) were investigated using a static immersion corrosion technique. Weight loss, surface microstructure, and corrosion depth of Mo and the TZM alloy were correlated with elements. The compatibility of Mo and the TZM alloy in static liquid Li was suitable. Mo demonstrated uniform corrosion with a homogenous dissolution of free C and Mo, and TZM alloy exhibited a nonuniform corrosion behaviour with a preferential grain boundary attack caused by the selective dissolution of free C, Ti, and Zr. When the surface oxidation layer of the samples was consumed, free C from Mo and TZM diffused into molten Li to form Li 2 C 2 and then was captured by Zr, Ti, and Mo to form thermodynamically stable carbides, which resulted in the enrichment of the C layer near the sample surfaces. In addition, Ti and Zr acted as N-trappers in liquid Li; the formation of Zr and Ti nitrides resulted in the enrichment of N, Ti, and Zr elements on the surface and led to TZM corrosion increase. Thus, Zr and Ti depletion, pitting, and grain boundary corrosion were problematic for TZM under long-term exposure to liquid Li. Reducing the content of free C and nonmetallic N and increasing the amount of Ti and Zr carbides on the surface of and inside the raw TZM alloy helped improve the corrosion resistance of TZM in liquid Li.
36 MATERIALS SCIENCE↗
Morphological study of borosilicate glass surface irradiated by heavy ions
Borosilicate glass is a candidate material for radiation waste formation and other optical applications in various fields. To understand the radiation effect of borosilicate glass, heavy ion (Ar q+ , Kr q+ and Xe q+ ) irradiations were used to simulate the alpha and recoiled nuclei irradiations in this study. The surface morphology of glass has been compared to ion irradiation doses and ion energies. The surface topography evolution of irradiated samples is characterized by optical microscopy, atomic force microscopy (AFM), transmission electron microscopy (TEM) and secondary ion mass spectrometry (SIMS). Micro-bumps are observed on the sample surface after irradiationwith 5 MeV Xe q+ over 5 × 10 13 ions·cm -2 . The size and density of the bumps increaseswith increasing irradiation dose. At a lowdose, bumps are on the nanometer (nm) scale and rather rare.While the dose is higher than 9 × 10 15 ions·cm -2 , the size of bumps is on the scale of a few microns, and the density is saturated. However, the height of the bumps increases froma fewnmto over 150nmwith further irradiation. The distribution of micro-bumps is nearly homogeneous. The bumps are condensed and swell up, and there is no crystallized structure according to the TEMdiffraction pattern. Elementmigration and concentrations are observedwith SIMS imaging. The arrayed micro-bumps are a new finding, and they might be used to change the surface properties. Bump formation is caused by phase separation, and volume swelling is induced by ion irradiation.
36 MATERIALS SCIENCE↗
Yield strength of Cu and a CuPb alloy (1% Pb)
With PBX9501 we explosively loaded fully annealed OFHC-Cu and an OFHC-CuPb (extruded with 1% Pb that ag- gregates at the Cu grain boundaries) to study the effects of the 1% Pb on the elastic-plastic yield Y of Cu. The yield-stress Y was studied through observation of surface velocimetry and total ejected mass ρ A from periodic surface perturbations machined onto the sample surfaces. The perturbation’s wavelengths were λ $\approx$ 65 µm, and their amplitudes h were varied to determine the wavenumber (2π/λ) amplitude product kh at which ejecta production for the Cu and CuPb begins, which relates to Y. The Y of the two materials is apparently different.
36 MATERIALS SCIENCE↗
Cleaning of GaN(2110) surfaces
The cleaning of GaN(2110) surfaces was investigated by x-ray photoelectron spectroscopy, scanning tunneling microscopy, and low-energy electron diffraction. Two different two-step cleaning methods, performed under ultrahigh-vacuum conditions, were carried out and compared. The first cleaning step of both methods is thermal degassing. The second step is either the deposition of metallic gallium followed by redesorption or an exposure to active nitrogen from a radio frequency nitrogen plasma source. Upon storage in a glovebox (N{sub 2} atmosphere) and transfer to ultrahigh vacuum under dry nitrogen, carbon and oxygen were identified as the major contaminants. A significant decrease in oxygen and carbon was achieved by thermal degassing at 750 deg. C under ultrahigh-vacuum conditions. By applying a subsequent Ga deposition/redesorption or N{sub 2}-plasma cleaning step, a further reduction in oxygen and carbon could be achieved. In comparison, the Ga deposition/redesorption cleaning showed a better performance in oxygen removal, whereas the N{sub 2} plasma exhibits a better efficiency in carbon removal. Furthermore scanning tunneling microscopy and low-energy electron diffraction investigations showed a drastic improvement of the morphology and atomic structure of the clean surfaces in contrast to the sample surfaces after N{sub 2} storage and transfer.
36 MATERIALS SCIENCE↗
Scanning tunneling microscopy of the atomically smooth (001) surface of vanadium pentoxide V{sub 2}O{sub 5} crystals
The (001) cleavage surface of vanadium pentoxide (V{sub 2}O{sub 5}) crystal has been studied by scanning tunneling spectroscopy (STM). It is shown that the surface is not reconstructed; the STM image allows geometric lattice parameters to be determined with high accuracy. The nanostructure formed on the (001) cleavage surface of crystal consists of atomically smooth steps with a height multiple of unit-cell parameter c = 4.37 Å. The V{sub 2}O{sub 5} crystal cleavages can be used as references in calibration of a scanning tunneling microscope under atmospheric conditions both along the (Ñ…, y) surface and normally to the sample surface (along the z axis). It is found that the terrace surface is not perfectly atomically smooth; its roughness is estimated to be ~0.5 Å. This circumstance may introduce an additional error into the microscope calibration along the z coordinate.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Effect of microplasma discharges on aluminum surfaces
Excitation of microplasma discharges on the surfaces of V95 aluminum alloy samples placed in a uniform pulsed plasma flow was studied experimentally. Strong localized interaction of microplasma discharges with aluminum leads to the melting and subsequent fast cooling of micrometer-size regions on the sample surface. Due to the multiple action of microplasma discharges, a continuous remelted layer with a thickness of up to 20 {mu}m forms on the aluminum surface. The physical, structural, and tribotechnical properties of this layer differ substantially from those before microplasma processing.
36 MATERIALS SCIENCE↗
Method for Processing Lunar Regolith Using Microwaves
A paper describes a method of using microwave heating experiments on lunar simulants to determine the mechanism that causes lunar regolith to be such an excellent microwave absorber. The experiments initially compared the effects of sharp particle edges to round particle edges on the heating curves. For most compositions, sharp particle edged samples were more effective in being heated by microwaves than round particle edged materials. However, the experiments also showed an unexpected effect for both types of particles. Upon heating the sample surface above 400 C, the sample experienced some sort of internal structure change that caused it to heat much more efficiently. This enhancement may be associated with the unique microwave volumetric heating that can produce a large temperature gradient within the sample leading to melting of some components at the center of the sample. This new effect that may also be happening in lunar regolith samples is probably the cause of the previously observed enhanced heating of a sample of lunar regolith. Properly designed microwave applicators could heat and solidify the lunar regolith to form roads and building blocks for structures needed on the Moon
Barmatz, Martin B.↗
Assessment of personal airborne exposures and surface contamination from x-ray vaporization of beryllium targets at the National Ignition Facility
Here, this article presents air and surface sampling data collected over the first two years since beryllium was introduced as a target material at the National Ignition Facility. Over this time, 101 experiments with beryllium-containing targets were executed. The data provides an assessment of current conditions in the facility and a baseline for future impacts as new, reduced regulatory limits for beryllium are being proposed by both the Occupational Safety and Health Administration and Department of Energy. This study also investigates how beryllium deposits onto exposed surfaces as a result of x-ray vaporization and the effectiveness of simple decontamination measures in reducing the amount of removable beryllium from a surface. Based on 1,961 surface wipe samples collected from entrant components (equipment directly exposed to target debris) and their surrounding work areas during routine reconfiguration activities, only one result was above the beryllium release limit of 0.2 µg/100 cm 2 and 27 results were above the analytical reporting limit of 0.01 µg/100 cm 2 , for a beryllium detection rate of 1.4%. Surface wipe samples collected from the internal walls of the NIF target chamber, however, showed higher levels of beryllium, with beryllium detected on 73% and 87% of the samples during the first and second target chamber entries (performed annually), respectively, with 23% of the samples above the beryllium release limit during the second target chamber entry. The analysis of a target chamber wall panel exposed during the first 30 beryllium-containing experiments (cumulatively) indicated that 87% of the beryllium contamination remains fixed onto the surface after wet wiping the surface and 92% of the non-fixed contamination was removed by decontaminating the surface using a dry wipe followed by a wet wipe. Personal airborne exposures assessed during access to entrant components and during target chamber entry indicated that airborne beryllium was not present in workers' breathing zones. Finally, all the data thus far have shown that beryllium has been effectively managed to prevent exposures to workers during routine and non-routine work.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Investigation of a possible solar-wind darkening of the lunar surface by photoelectron spectroscopy.
Detailed sequential study by photoelectron spectroscopy of the change in valence states of iron in Fe2O3, Fe3O4, FeO, and Fe foil samples, showing that chemical reduction does take place on the sample surface when argon ion bombardment occurs. These spectra give evidence that, after prolonged ion bombardment, the surface of all four samples consisted predominantly of iron in the metallic state. Argon ion sputtering of 15 silicate and oxide samples under similar experimental conditions produced surface darkening only in samples containing iron. Monitoring of the photoelectron peak of carbon during the experiment indicates that ion-bombardment darkening is not due to the buildup of hydrocarbon surface contaminants in the oil-free high-vacuum system used by the authors. On the basis of these studies, it is concluded that solar-wind bombardment should be included as one of the possible mechanisms for producing darkening of the lunar surface.
Yin, L. I.↗
Improved spatial resolution for spot sampling in thermal desorption atomic force microscopy – mass spectrometry via rapid heating functions
The key to advancing materials is to understand and control their structure and chemistry. However, thorough chemical characterization is challenging since existing techniques characterize only a few properties of the specimen, thereby necessitating multiple measurement platforms to acquire the necessary information. The multimodal combination of atomic force microscopy (AFM) and mass spectrometry (MS) transcends existing analytical capabilities for nanometer scale spatially resolved correlation of the chemical and physical properties of a sample surface. One such hybrid system employs heated AFM cantilevers for thermal desorption (TD) sampling of molecules from a surface and subsequent gas phase ionization and detection of the liberated species by MS. Here in this paper, we report on the use of voltage pulse trains to tailor cantilever heating such that spot sampling size was reduced and mass spectral signal was improved compared to constant voltage, static heating of the cantilever. Desorption efficiency (DE), defined as the quotient of the mass spectral signal intensity and the volume of the desorption crater, was used to judge the effectiveness of a particular tailored heating function. To guide the development and optimization of the heating functions and aid in interpreting experimental results, a 1D finite element model was developed that predicted the cantilever response to different heating functions. Three tailored heating functions that used different combinations, magnitudes, and durations of rectangular voltage pulses, were used for surface spot sampling. The resultant sampling spot size and DE were compared to the same metrics obtained with the conventional method that uses a single voltage pulse. Using a model system composed of a thin film of ink containing pigment yellow 74 as a model system, desorption craters shrunk from 2 μm, using the conventional approach, to 310 nm using the optimum tailored heating function. This same pulsed heating function produced a 381× improvement in the DE and an 8× improvement in spatial resolution compared to the conventional heating approach showing that signal/amount of material sampled was improved significantly by this new cantilever heating strategy.
36 MATERIALS SCIENCE↗
RIA simulation tests using driver tube for ATF cladding
Pellet-cladding mechanical interaction (PCMI) is a potential failure mechanism for accident-tolerant fuel (ATF) cladding candidates during a reactivity-initiated accident (RIA). This report summarizes Fiscal Year (FY) 2017 research activities that were undertaken to evaluate the PCMI-like hoop-strain-driven mechanical response of ATF cladding candidates. To achieve various RIA-like conditions, a modified-burst test (MBT) device was developed to produce different mechanical pulses. The calibration of the MBT instrument was accomplished by performing mechanical tests on unirradiated Generation-I iron-chromium-aluminum (FeCrAl) alloy samples. Shakedown tests were also conducted in both FY 2016 and FY 2017 using unirradiated hydrided ZIRLO™ tube samples. This milestone report focuses on testing of ATF materials, but the benchmark tests with hydrided ZIRLO™ tube samples are documented in a recent journal article.a For the calibration and benchmark tests, the hoop strain was monitored using strain gauges attached to the sample surface in the hoop direction. A novel digital image correlation (DIC) system composed of a single high-speed camera and an array of six mirrors was developed for the MBT instrument to better resolve the failure behavior of samples and to provide useful data for validation of high-fidelity modeling and simulation tools. The DIC system enable a 360° view of a sample’s outer surface. This feature was added to the instrument to determine the precise failure location on a sample’s surface for strain predictions. The DIC system was tested on several silicon carbide fiber/silicon carbide matrix (SiC/SiC) composite tube samples at various pressurization rates of the driver tube (which correspond to the strain rates for the samples). The hoop strains for various loading conditions were determined for the SiC/SiC composite tube samples. Future work is planned to enhance understanding of the failure behavior of the ATF cladding candidates of age-hardened FeCrAl alloys and SiC/SiC composites in detail during RIA conditions informed by the computational studies performed under the US Department of Energy Office of Nuclear Energy Advanced Fuels Campaign. The testing instrument and the new DIC system will be further developed to reach different stress-state conditions and to perform tests at elevated temperatures.
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
Mars Sample Recovery Helicopter: Rotorcraft to Retrieve the First Samples from the Martian Surface
The Mars Sample Return Mission (MSR) will carry the next set of Mars helicopters, Sample Recovery Helicopters (SRHs), to the Martian surface. After successfully demonstrating extraterrestrial flight in 2021, Ingenuity has acted as a “scout” for the Perseverance rover while the rover gathers samples of Martian soil. In 2028, the MSR mission will launch a lander and two Ingenuity-sized SRHs to retrieve these samples. These will be the first samples of the Martian surface delivered to Earth. The SRH project will maintain heritage from Ingenuity’s design when possible. However, several key changes must be made, including a ground mobility system, a robotic arm for tube manipulation, and the ability to carry the weight of a science payload (the sample tubes). In addition, the onboard software and cameras will be upgraded, and the rotor radius will be increased. Furthermore, new rotor performance and flight dynamics models and thorough characterization of vehicle limits will be required. The new vehicle design will be described, as well as validation and verification efforts to date.
Rotorcraft↗
Integrated GNC Modifications and Performance Assessments for the Mars Ascent Vehicle, Spin-Stabilized Upper Stage Configuration
The objective of the Mars Ascent Vehicle (MAV), an element of the Mars Sample Return (MSR) campaign, is to successfully transport Martian surface samples from the Martian surface to a stable Low-Martian Orbit. Complete autonomy is required throughout ascent, and orbital insertion is constrained by tight dispersion boundaries. Given mass requirements to merely transport the MAV onto the Martian surface, reducing the total mass of the MAV reduces stress on all other campaign elements. An unguided, spin-stabilized second stage MAV allows for lower overall vehicle mass, at the cost of reduced GNC capability. This paper presents GNC modifications developed and employed to improve the performance of an unguided, spin-stabilized second stage MAV configuration. These updates include a predictive calculation scheme to solve the spin-stabilized attitude necessary for successful orbital insertion, and a spin-stabilized control law for a preliminary low-rate first stage spin-up. Trades were conducted focusing on first and second stage low-rate and high-rate spin rates (and other factors) in MSFC's MANTIS toolkit through 6-degree-of-freedom simulation and Monte Carlo analysis, and are presented here.
Dane Erickson↗