Gas Standards Development in Support of NASA’s Sensor Calibration Program Around the Space Shuttle

The National Institute of Standards and Technology (NIST) has been certifying lots, or series, of Standard Reference Materials (SRMs) containing ambient level methane in air for over 40 years. The historical record contains six traditional series of SRM 1658 (1 μmol mol(-1)), five of SRM 1660 (4 μmol mol(-1)), and seven of SRM 1659 (10 μmol mol(-1)) methane in air. All series of any one particular SRM can be linked to each other through the historical suites of gravimetric primary standard mixtures (PSMs) developed at NIST. One gas mixture cylinder from a series is chosen as the lot standard (LS), retained and held at NIST, and periodically compared to the PSMs to assure its stability. Recently, 6 of the original 18 LS still in service in the Gas Metrology Group inventory, and cylinder samples held at NIST from 6 other SRM lots, were analyzed against a newly prepared suite of PSMs using cavity ring-down spectroscopy. Data were analyzed using a generalized least squares linear regression. The results indicate that, within the original 95% confidence intervals, the methane concentration has remained the same for all the SRM LS and lot samples. The current predicted concentrations of the LS and samples for SRMs 1659 and 1660 are within 0.002 to 0.051 μmol mol(-1), or ≤0.5%, relative of the original certificate value. SRM 1658 LS and samples are within 0.0001 to 0.0023 μmol mol(-1), or ≤0.2% relative. These results illustrate the consistency, repeatability, and stability of these methane in air SRMs over the historical 35+-year record. It also demonstrates that the historical gravimetric primary methane in air suites have remained accurate and consistent over time.

Between June 2010 and June 2011, the National Institute of Standards and Technology (NIST) gravimetrically prepared a suite of 20 carbon dioxide (CO2) in air primary standard mixtures (PSMs). Ambient mole fraction levels were obtained through six levels of dilution beginning with pure (99.999%) CO2. The sixth level covered the ambient range from 355 to 404 μmol/mol. This level will be used to certify cylinder mixtures of compressed dry whole air from both the northern and southern hemispheres as NIST standard reference materials (SRMs). The first five levels of PSMs were verified against existing PSMs in a balance of air or nitrogen with excellent agreement observed (the average percent difference between the calculated and analyzed values was 0.002%). After the preparation of a new suite of PSMs at ambient level, they were compared to an existing suite of PSMs. It was observed that the analyzed concentration of the new PSMs was less than the calculated gravimetric concentration by as much as 0.3% relative. The existing PSMs had been used in a Consultative Committee for Amount of Substance-Metrology in Chemistry Key Comparison (K-52) in which there was excellent agreement (the NIST-analyzed value was -0.09% different from the calculated value, while the average of the difference for all 18 participants was -0.10%) with those of other National Metrology Institutes and World Meteorological Organization designated laboratories. In order to determine the magnitude of these losses at the ambient level, a series of "daughter/mother" tests were initiated and conducted in which the gas mixture containing CO2 from a "mother" cylinder was transferred into an evacuated "daughter" cylinder. These cylinder pairs were then compared using cavity ring-down spectroscopy under high reproducibility conditions (the average percent relative standard deviation of sample response was 0.02). A ratio of the daughter instrument response to the mother response was calculated, with the resultant deviation from unity being a measure of the CO2 loss or gain. Cylinders from three specialty gas vendors were tested to find the appropriate cylinder in which to prepare the new PSMs. All cylinders tested showed a loss of CO2, presumably to the walls of the cylinder. The vendor cylinders exhibiting the least loss of CO2 were then purchased to be used to gravimetrically prepare the PSMs, adjusting the calculated mole fraction for the loss bias and an uncertainty calculated from this work.

The National Institute of Standards and Technology (NIST) recently began to develop standard mixtures of greenhouse gases as part of a broad program mandated by the 2009 United States Congress to support research in climate change. To this end, NIST developed suites of gravimetrically assigned primary standard mixtures (PSMs) comprising carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) in a dry-natural air balance at ambient mole fraction levels. In parallel, the National Oceanic and Atmospheric Administration (NOAA) in Boulder, Colorado, charged 30 aluminum gas cylinders with northern hemisphere air at Niwot Ridge, Colorado. These mixtures, which constitute NIST Standard Reference Material (SRM) 1720 Northern Continental Air, were certified by NIST for ambient mole fractions of CO2, CH4, and N2O relative to NIST PSMs. NOAA-assigned values are also provided as information in support of the World Meteorological Organization (WMO) Global Atmosphere Watch (GAW) Program for CO2, CH4, and N2O, since NOAA serves as the WMO Central Calibration Laboratory (CCL) for CO2, CH4, and N2O. Relative expanded uncertainties at the 95% confidence interval are <±0.06% of the certified values for CO2 and N2O and <0.2% for CH4, which represents the smallest relative uncertainties specified to date for a gaseous SRM produced by NIST. Agreement between the NOAA (WMO/GAW) and NIST values based on their respective calibration standards suites is within 0.05%, 0.13%, and 0.06% for CO2, CH4, and N2O, respectively. This collaborative development effort also represents the first of its kind for a gaseous SRM developed by NIST.

Nist role in radiometric calibrations for remote sensing programs at NASA, NOAA, DOE and DOD

The National Institute of Standards and Technology (NIST) is the National Measurement Institute (NMI) for the US. All dosimetric measurements made in American radiotherapy clinics should be traceable to the primary standards maintained by NIST. The accuracy of the NIST standards, and traceability to the Systeme Internationale (SI), is ensured through the Bureau International des Poids et Mesures (BIPM), the international laboratory that co‐ordinates comparisons between NIST and other NMIs around the world (such as the National Research Council Canada). A continuous calibration chain, therefore, links the measurement of dose in the clinic to the internationally agreed‐upon definition of the gray, an essential requirement in ensuring equivalence of clinical dose delivery irrespective of location. Within the US, traceability of radiationdose measurements to the SI is ensured through activities of the Radiation Interactions and Dosimetry (RID) Group at NIST, whose primary mission is to develop, maintain, and disseminate the national measurement standards for the dosimetry of x rays,gamma rays, electrons, and other charged particles. In the case of medical dosimetry, relevant standards are disseminated both directly to the customer and through the AAPM Accredited DosimetryCalibration Laboratory (ADCL) network by means of calibrations and proficiency testing services, provided to maintain measurement‐quality assurance and traceability. The evolving measurement needs of industry, medicine and government provide impetus for the improvement of existing standards and the development of new standards. Research activities in support of this part of the RID Group's mission address a variety of topics in fundamental and applied radiation physics. These efforts are driven partly by advancements in instrumentation technology and partly by the ever expanding domain of measurement standards made possible by such advancements. The widespread adoption of conformal beam therapies, for example, has driven the standards community to develop new approaches for standard reference dosimetry of “nonstandard” beams. At NIST, this has spurred a research program in water calorimetry that is looking into ultrasonic time‐of‐flight approaches to imagingdose in water. Ultimately, this or similar approaches might lead to new ways of imaging complicated dose distributions in tissue as well as give the standards community new tools for reference dosimetry of present and future beam technologies. In this session, attendees will learn how the accuracy of their clinical measurements is assured as a result of comparisons between NIST and other NMIs around the world as well as NIST proficiency tests and AAPM accreditation of the ADCLs. It will be shown how NIST staff members are active within critical AAPM scientific committees so that measurement needs in the clinic can be addressed by the standards laboratory, resulting in the development of new standards and/or methodologies. Learning Objectives: 1. Understand the impact of measurement standards in general, and in particular the work of primary standards laboratories such as NIST, on clinical radiationdosimetry. 2. Understand the calibration chain from primary standards laboratory to radiotherapy clinic. 3. Understand how NIST interacts with various AAPM committees to ensure that the measurement needs of the user community are met.

ABSTRACTThe National Institute of Standards and Technology (NIST) has developed a dynamic and on-going educational outreach program designed to support middle school science teachers and increase their understanding of the science they teach with applications to the real world and connections to the latest NIST research. In the NIST Summer Institute for Middle School Science Teachers, science topics are taken from NIST research pertinent to the middle school curriculum, and the research is translated for use in the classroom. During the two-week summer program teachers from around the country are given the opportunity to focus on NIST research as it relates to the middle school classroom by participating in a combination of hands-on activities, lectures, tours, and visits with scientists and engineers in their laboratories. The NIST Summer Institute is designed to increase teacher understanding of the subjects they teach, provide inquiry activities for the classroom, rekindle teachers’ enthusiasm for science, provide increased understanding of how scientific research is performed, create a learning community of teachers and scientists, and provide role models for the teachers. Teachers finish the NIST Summer Institute with a wealth of knowledge about core topics in introductory biology, chemistry, physics, and materials to integrate these topics into their existing curriculum.The NIST Summer Institute has spawned additional related outreach activities, including “Science Afternoons at NIST,” in which teachers are invited back to NIST during the school year for events in which the focus is on a single topic such as designing buildings to resist earthquakes, infrared energy, and nanomagnetism. Based on continued requests from participants in the NIST Summer Institute, an additional program, the NIST Research Experience for Teachers program, was begun in 2011 with teachers performing research at NIST under the guidance of NIST scientists and engineers, and designing ways to take their research experience back into the classroom to share with their students. This proceeding will give examples of topics covered and activities developed in past Summer Institutes, as well as ways similar Institutes are being implemented at other locations. While not a teaching institution but a research institute focused on meeting the measurement science needs of the nation, NIST has a wealth of resources for the education community. The NIST Summer Institute for Middle School Science Teachers is one way of sharing these resources and building partnerships between middle school science teachers and their students and NIST scientists and engineers.

Fatality Risks on the Road and in Space

Fused silica diffusers, made by forming scattering centers inside fused silica glass, can exhibit desirable optical properties, such as reflectance or transmittance independent of viewing angle, spectrally flat response into the ultraviolet wavelength range, and good spatial uniformity. The diffusers are of interest for terrestrial and space borne remote sensing instruments, which use light diffusers in reflective and transmissive applications. In this work, we report exploratory measurements of two samples of fused silica diffusers. We will present goniometric bidirectional scattering distribution function (BSDF) measurements under normal illumination provided by the National Institute of Standards and Technology (NIST)'s Goniometric Optical Scatter Instrument (GOSI), by NIST's Infrared reference integrating sphere (IRIS) and by the National Aeronautics and Space Administration (NASA)'s Diffuser Calibration Laboratory. We also present hemispherical diffuse transmittance and reflectance measurements provided by NIST's Double integrating sphere Optical Scattering Instrument (DOSI). The data from the DOSI is analyzed by Prahl's inverse adding-doubling algorithm to obtain the absorption and reduced scattering coefficient of the samples. Implications of fused silica diffusers for remote sensing applications are discussed.

A program is described by which the concentration of commercially produced gas mixtures may be related to gaseous primary standards maintained by the National Institute of Standards and Technology (NIST). The gaseous mixtures, referred to as gas mixture NIST Traceable Reference Materials (NTRMs), must be similar in composition to NIST primary standards and the concentration of the certified component must be at, or bracketed by, primary standards. Although the NTRM gas mixtures are produced and distributed by commercial vendors, the concentration value assignment is made by NIST. The responsibilities of the producer and NIST are detailed along with recommended procedures the producer should follow during production and analysis of the mixtures. Procedures also are included for the maintenance of NTRM batches. Appendices are included for the preparation of NTRMs related to various Standard Reference Materials.

The 10th North American Josephson voltage standard (JVS) interlaboratory comparison (ILC) at 10 V was completed in 2014. This year’s ILC was unique as it consisted of 2 parts. An on-site comparison was conducted between the National Institute of Standards and Technology (NIST) compact JVS and the pivot laboratory’s conventional JVS (CJVS) system. A set of four traveling Zener voltage standards then served to transfer traceability from the pivot laboratory to the 12 other participants. In addition to the regular ILC activities, a second on-site comparison was conducted between the NIST compact JVS and the programmable JVS (PJVS) provided by the National Aeronautics and Space Administration (NASA). Due to limited availability of the PJVS, only two labs were selected to make direct comparison between their CJVS systems and NASA’s PJVS. The method has been used for the first time in the JVS ILC and has the advantage of using the PJVS as a transfer standard. This allowed the participating lab to make comparisons using its CJVS system against the 10V PJVS in the same manner as the measurements for Zener standards are performed while overcoming limitations of the Zener noise. We give the results from the 2014 ILC.

The National Aeronautics and Space Administration (NASA) invests millions of dollars in spacecraft and ground system development, and in mission operations in the pursuit of scientific knowledge of the universe. In recent years, NASA sent a probe to Mars to study the Red Planet's upper atmosphere, obtained high resolution images of Pluto, and it is currently preparing to find new exoplanets, rendezvous with an asteroid, and bring a sample of the asteroid back to Earth for analysis. The success of these missions is enabled by mission assurance. In turn, mission assurance is backed by information assurance. The information systems supporting NASA missions must be reliable as well as secure. NASA - like every other U.S. Federal Government agency - is required to manage the security of its information systems according to federal mandates, the most prominent being the Federal Information Security Management Act (FISMA) of 2002 and the legislative updates that followed it. Like the management of enterprise information technology (IT), federal information security management takes a "one-size fits all" approach for protecting IT systems. While this approach works for most organizations, it does not effectively translate into security of highly specialized systems such as those supporting NASA missions. These systems include command and control (C&amp;C) systems, spacecraft and instrument simulators, and other elements comprising the ground segment. They must be carefully configured, monitored and maintained, sometimes for several years past the missions' initially planned life expectancy, to ensure the ground system is protected and remains operational without any compromise of its confidentiality, integrity and availability. Enterprise policies, processes, procedures and products, if not effectively tailored to meet mission requirements, may not offer the needed security for protecting the information system, and they may even become disruptive to mission operations. Certain protective measures for the general enterprise may not be as efficient within the ground segment. This is what the authors have concluded through observations and analysis of patterns identified from the various security assessments performed on NASA missions such as MAVEN, OSIRIS-REx, New Horizons and TESS, to name a few. The security audits confirmed that the framework for managing information system security developed by the National Institute of Standards and Technology (NIST) for the federal government, and adopted by NASA, is indeed effective. However, the selection of the technical, operational and management security controls offered by the NIST model - and how they are implemented - does not always fit the nature and the environment where the ground system operates in even though there is no apparent impact on mission success. The authors observed that unfit controls, that is, controls that are not necessarily applicable or sufficiently effective in protecting the mission systems, are often selected to facilitate compliance with security requirements and organizational expectations even if the selected controls offer minimum or non-existent protection. This paper identifies some of the standard security controls that can in fact protect the ground system, and which of them offer little or no benefit at all. It offers multiple scenarios from real security audits in which the controls are not effective without, of course, disclosing any sensitive information about the missions assessed. In addition to selection and implementation of controls, the paper also discusses potential impact of recent legislation such as the Federal Information Security Modernization Act (FISMA) of 2014 - aimed at the enterprise - on the ground system, and offers other recommendations to Information System Owners (ISOs).

The Landsat Data Continuity Mission (LDCM) project at the National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC) is supervising the manufacture and calibration of the Operational Land Imager (OLI) satellite instrument by Ball Aerospace in Boulder, Colorado. As part of that oversight function, the project is preparing a set of radiometers to monitor long-term changes (if any) in the radiance from the integrating sphere used for the radiance calibration of the OLI instrument. That sphere, calibrated at the National Institute of Standards and Technology (NIST), serves as an artifact for establishing traceability of the OLI radiance calibration to SI units, that is, to the radiance scale at NIST. This paper addresses the characterization of two Analytic Spectral Devices (ASD) Fieldspec spectrometers that are part of the NASA/NIST program to validate radiometric reference standards in the LDCM project. In particular, we report on a series of measurements at NIST to determine the ASD spectrometers' long-term stability. Along with other radiometers, the ASDs will be used in the monitoring of changes in the OLI reference sphere from its calibration at NIST to its use in the calibration of the OLI satellite instrument. The ASD stability measurements will continue through the conclusion of the calibration of OLI.

Exo-atmospheric solar irradiance measurements made by the solar irradiance community since 1978 have incorporated limiting apertures with diameters measured by a number of metrology laboratories using a variety of techniques. Knowledge of the aperture area is a critical component in the conversion of radiant flux measurements to solar irradiance. A National Aeronautics and Space Administration (NASA) Earth Observing System (EOS) sponsored international comparison of aperture area measurements of limiting apertures provided by solar irradiance researchers was performed, the effort being executed by the National Institute of Standards and Technology (NIST) in coordination with the EOS Project Science Office. Apertures that had institutional heritage with historical solar irradiance measurements were measured using the absolute aperture measurement facility at NIST. The measurement technique employed noncontact video microscopy using high-accuracy translation stages. We have quantified the differences between the participating institutions' aperture area measurements and find no evidence to support the hypothesis that preflight aperture area measurements were the root cause of discrepancies in long-term total solar irradiance satellite measurements. Another result is the assessment of uncertainties assigned to methods used by participants. We find that uncertainties assigned to a participant's values may be underestimated.

One element of a multi-year calibration program between the National Institute of Standards and Technology (NIST) and the National Aeronautical and Space Administration (NASA) Earth Observing System (EOS) Project Science Office has been the development and deployment of a portable transfer radiometer for verifying the thermal-infrared scales being used for flight-instrument pre-launch calibration. This instrument, the Thermal-infrared Transfer Radiometer (TXR), has been built and the first deployment test was completed successfully, as has been reported previously.1 The 5 µm channel, based on a photovoltaic Indium Antimonide (InSb) detector, so far has demonstrated a pre-deployment to post-deployment uncorrected repeatability of better than 30 mK to 60 mK, which is sufficient to enable intercomparisons at useful uncertainty levels for the EOS program. However, the 10 µm channel, based on a photovoltaic Mercury Cadmium Telluride (MCT) detector, shows uncorrected repeatability levels of about 0.5 K, the response changes being induced by cryocycling. This paper describes the technique that has been developed for correcting these changes. A portable black body check-source travels with the TXR that is used to verify the repeatability during the deployment trip. The check-source, in combination with the stability of the 5 µm channel, is used to restore a higher accuracy scale to the 10 µm channel than would otherwise be possible. This application is analogous to the use of an on-orbit calibration source to check for and correct for launch-induced or degradation-induced flight instrument detector response changes.

Background: Molecular diagnostics provide early and accurate diagnosis, which is essential for the prevention and treatment of infectious as well as chronic diseases. These tests are designed to detect disease-specific bioanalytes such as nucleic acid (DNA or RNA) or protein (antigens, antibodies) biomarkers. In the context of infectious disease diagnosis, nucleic acid-based detection methods are known to provide more specific and sensitive results. Here, the presence of a unique sequence belonging to the pathogenic genomic material is targeted to identify species, organism, genera and/or antimicrobial resistant gene markers. The majority of the common nucleic acid based diagnostic techniques require amplification (polymerase chain reaction, isothermal amplification etc.) of the pathogenic genetic material prior to detection impacting diagnostic speed, complexity, and cost thereby limiting ease of use. Thus, the development of simplified nucleic acid-based diagnostics that can be even used in resource-poor settings may hugely benefit patients across the globe.Nanopath is a molecular diagnostics company utilizing a solid-state nanosensor to enable sequence-specific detection of target nucleic acids without the need of amplification. These nanostructures enable ultra-sensitive biomarker detection using geometric, feature-dependent properties highly dependent on the local dielectric environment, allowing them to be sensitive to low concentration binding events. This paper describes an application of this approach to provide highly relevant clinical information within a single doctor’s office visit. Introduction: The Nanopath team is in collaboration with NASA (National Aeronautics and Space Administration) and NIST (National Institute of Standards and Technology) to push the bounds of the fundamental physics associated with their biosensing platform. The ability of metals to support electromagnetic surface waves gives rise to surface plasmons when optically illuminated. This property, and its strong sensitivity to changes in the local refractive index, allows for the use of metal nanoparticles as ultra-sensitive transducers. In prior work by members of this team, ensembles of randomly oriented nanoparticles (i.e., colloidal nanorods dispersed on chip) were employed for sequence-specific nucleic acid sensing (1-3). While these particle sensors have the advantage of rapid fabrication, they suffer from low sensitivity and quality factor due to the random particle dispersity. In contrast, in this study we employ ordered array nanoparticle ensembles which can be used to improve sensor sensitivity and figure-of-merit. Study Methods Overview: In this talk, we detail the results of sensing experiments and computational simulations to outline a rational design of the structure of these plasmonic nanoparticle arrays for biomolecular sensing. Through simulation and experiment, we iteratively tailor nanostructure dimension to provide high quality signal and large resonance shifts upon modeled nucleic acid binding.In particular, full-wave electromagnetic simulations were conducted using Lumerical photonic simulation software in which periodic boundary conditions were applied in the x- and y- dimensions for each of the nanoplasmonic sensor geometries. To simulate the resonance response to changes in the bulk solution in contact with the sensor surface, the refractive index of the surrounding media was changed appropriately. Nucleic acid hybridization events were modeled using either using spherical structures approximating the relevant radius of genomic material as estimated by polymer models, or as conformal layers with the known refractive indices for nucleic acids. On the basis of initial simulations, nanosensors were fabricated using traditional electron-beam lithography protocols at NIST. To evaluate consensus between simulations and experiments, bulk sensing experiments were carried out in which the resonance peaks were obtained by submerging the sensors in refractive index standards. Key nanosensor characteristics including resonance peak locations, resonance peak shifts as a function of refractive index, and figure of merit (FOM) of extinction curves were examined between the experimental and simulation results prior to proceeding with simulations on additional geometries and more complex solution conditions, and further device fabrication. This iterative process is repeated toward a rational design of nanoplasmonic array geometries for biosensing optimizing response for targeted disease detection.In summary, this study puts forth a methodology for rational design and characterization of regularly spaced nanoparticle arrays for optics-based biosensing. The results of this study will allow for more informed design of nanostructure geometries towards sequence-specific nucleic acid detection. These improved designs have the potential to improve clinical sensitivity and limit-of-detection across disease indication.