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At least 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Initial Field Testing in the Deep Subsurface for the Thermal Breakout Project for Measuring In Situ Stress

The current state-of-the-art technology for in situ stress measurements involves an integrated approach that combines borehole breakout observations, drilling-induced tensile fractures, and hydraulic fracturing tests (i.e., mini-fracs); however, this methodology has several limitations that often prevent successful in situ stress measurements. One major limitation is that breakouts do not appear in every borehole and are generally a natural occurrence that cannot easily be controlled. Because borehole breakouts are used to measure the maximum horizontal in situ stress magnitude, the absence of borehole breakouts presents a major data gap for in situ stress measurements. As a response to this data gap a new thermal breakout technology is being developed that will provide a method for thermally inducing borehole breakouts and obtaining consistent measurements of the maximum horizontal stress magnitude. This thermal breakout technology involves heating the borehole and increasing the thermoelastic compressive stress in the rock until a breakout develops, which is directly correlated to the maximum horizontal stress magnitude. An initial component of the thermal breakout project involves developing a prototype downhole tool and performing field testing in the deep subsurface. The primary objective of the initial tool development and field testing is to provide a physical proof of concept for the thermal breakout technology. Three thermal breakout field tests were performed at approximately 4850 feet deep in the Sanford Underground Research Facility. Each test was performed in a borehole that had been previously used for overcoring stress measurements. The third and final test successfully created two diametrically opposed breakouts after deploying the thermal breakout tool for approximately 3 hours of continuous heating. Post-analysis of the thermally induced breakouts confirmed that the thermal breakout orientation directly corresponds to the known in situ stress orientation and magnitude.

Voegeli, Sam↗
NASA NTRS1984

Intercomparisons of temperature, density and wind measurements from in situ and satellite techniques

Atmospheric temperature, density, and wind data retrieved by various means are intercompared, covering the 1980-1984 period. The study encompasses such data sources as radiosonde, rocketsonde, in situ measurements, remote measurements, satellites, and NOAA-6 and 7 TOVS data. Larger temperature differences (up to 7-8 K) are noted for the rocketsonde/satellite comparison than for the radiosonde/satellite comparison (less than 1 K). The rocketsonde measurements were found to be internally consistent to less than 1 K up to 50 km and to less than 3 K up to 60 km. A general agreement of the density data obtained from small rocketsondes and large sounding rocket systems is suggested to be within 15 percent up to 85 km of altitude. The usefulness of intermixing the measurements of the various atmospheric parameters obtained from different instruments is emphasized, and some suggestions are made concerning the approaches to such intermixing.

Schmidlin, F. J.↗
NASA NTRS1993

Micro-sensors for in-situ meteorological measurements

Improved in-situ meteorological measurements are needed for monitoring the weather and climate of the terrestrial and Martian atmospheres. We have initiated a program to assess the feasibility and utility of micro-sensors for precise in-situ meteorological measurements in these environments. Sensors are being developed for measuring pressure, temperature, wind velocity, humidity, and aerosol amounts. Silicon micro-machining and large scale integration technologies are being used to make sensors that are small, rugged, lightweight, and require very little power. Our long-term goal is to develop very accurate miniaturized sensors that can be incorporated into complete instrument packages or 'micro weather stations,' and deployed on a variety of platforms. If conventional commercially available silicon production techniques can be used to fabricate these sensor packages, it will eventually be possible to mass-produce them at low cost. For studies of the Earth's troposphere and stratosphere, they could be deployed on aircraft, dropsondes, radiosondes, or autonomous surface stations at remote sites. Improved sensor accuracy and reduced sensor cost are the primary challenges for these applications. For studies of the Martian atmosphere, these sensor packages could be incorporated into the small entry probes and surface landers that are being planned for the Mars Environmental SURvey (MESUR) Mission. That decade-long program will deploy a global network of small stations on the Martian surface for monitoring meteorological and geological processes. Low mass, low power, durability, large dynamic range and calibration stability are the principal challenges for this application. Our progress on each of these sensor types is presented.

Crisp, David↗
NASA NTRS1992

Micro-Sensors for in-situ Meteorological Measurements

Improved in-situ meteorological measurements are needed for monitoring the weather and climate of the terrestrial and martian atmospheres. We have initiated a program to assess the feasibility and utility of micro-sensors for precise in-situ meteorological measurements in these environments. Sensors are being developed for measuring pressure, temperature, wind velocity, humidity, and aerosol amounts.

Micro-Sensors↗
NASA NTRS2015

The Radiation Stability of Glycine in Solid CO2 - In Situ Laboratory Measurements with Applications to Mars

The detection of biologically important, organic molecules on Mars is an important goal that may soon be reached. However, the current small number of organic detections at the martian surface may be due to the harsh UV and radiation conditions there. It seems likely that a successful search will require probing the subsurface of Mars, where penetrating cosmic rays and solar energetic particles dominate the radiation environment, with an influence that weakens with depth. Toward the goal of understanding the survival of organic molecules in cold radiation-rich environments on Mars, we present new kinetics data on the radiolytic destruction of glycine diluted in frozen carbon dioxide. Rate constants were measured in situ with infrared spectroscopy, without additional sample manipulation, for irradiations at 25, 50, and 75 K with 0.8-MeV protons. The resulting half-lives for glycine in CO2-ice are compared to previous results for glycine in H2O-ice and show that glycine in CO2-ice is much less stable in a radiation environment, with destruction rate constants approximately 20-40 times higher than glycine in H2O-ice. Extrapolation of these results to conditions in the martian subsurface results in half-lives estimated to be less than 100-200 Myr even at depths of a few meters.

Ices↗
NASA NTRS1986

Overview of VEGA Venus balloon in situ meteorological measurements

The VEGA balloons made in situ measurements of pressure, temperature, vertical wind velocity, ambient light, frequency of lightning, and cloud particle backscatter. Both balloons encountered highly variable atmospheric conditions, with periods of intense vertical winds occurring sporadically throughout their flights. Downward winds as large as 3.5 meters per second occasionally forced the balloons to descend as much as 2.5 kilometers below their equilibrium float altitudes. Large variations in pressure, temperature, ambient light level, and cloud particle backscatter (VEGA-1 only) correlated well during these excursions, indicating that these properties were strong functions of altitude in those parts of the middle cloud layer sampled by the balloons.

Sagdeev, R. Z.↗
NASA NTRS1988

Comparison of in situ aerosol measurements with SAGE 2 and SAM 2 aerosol measurements during the airborne Antarctic ozone experiment

Models indicate that stratospheric aerosols play a major role in the destruction of ozone during the Austral winter. Although many in situ measurements of stratospheric aerosols were made during the Airborne Antarctic Ozone Experiment, changes of aerosol concentration and size distributions across the polar vortex are important to understanding changes of chemical species taking place during this time. Therefore comparing the in situ measurements with measurements made by satellites scanning wider areas will give a clearer picture of the possible role played by aerosols during this period. The wire impactor size distributions are compared to those from the aerosol spectrometers and a best fit size distribution determined. Aerosol extinctions are calculated from the in situ measurements and compared to the extinctions measured by the satellites. Five comparisons are made with SAGE 2 and four with SAM 2. Extinctions agree as close as a factor of two.

Ferry, G. V.↗
NASA NTRS2011

Monitoring D-Region Variability from Lightning Measurements

In situ measurements of ionospheric D-region characteristics are somewhat scarce and rely mostly on sounding rockets. Remote sensing techniques employing Very Low Frequency (VLF) transmitters can provide electron density estimates from subionospheric wave propagation modeling. Here we discuss how lightning waveform measurements, namely sferics and tweeks, can be used for monitoring the D-region variability and day-night transition, and for local electron density estimates. A brief comparison among D-region aeronomy models is also presented.

Simoes, Fernando↗
NASA NTRS1987

Remote versus in situ turbulence measurements

Comparisons of in situ wind and turbulence measurements made with the NASA B-57 instrumented aircraft and those remotely made with both radar and lidar systems are presented. Turbulence measurements with a lidar or radar system as compared with those from an aircraft are the principal themes. However, some discussion of mean wind speed and direction measurements is presented. First, the principle of measuring turbulence with Doppler lidar and radar is briefly and conceptually described. The comparisons with aircraft measurements are then discussed. Two studies in particular are addressed: one uses the JAWS Doppler radar data and the other uses data gathered both with the NASA Marshall Space Flight Center and the the NOAA Wave Propagation Lab. gound based lidars. Finally, some conclusions and recommendations are made.

Frost, Walter↗
NASA NTRS2020

Enabling Entry Technologies for Ice Giant Missions

The highest priority science goals for Ice Giant missions are: 1) Interior structure of the Planet, and 2) Bulk composition that includes isotopes and noble gases. The interaction between the planetary interior and the atmosphere requires sustained global measurements. Noble gas and Isotope measurements require in situ measurement. Drag modulated aerocapture utilizing ADEPT offers more mass delivered to the Ice Giants than with propulsive orbit insertion. The Galileo Probe entered at a ‘hot’ spot which created interpretation challenges. Juno is providing valuable orbital measurements, but without in situ measurements the story is incomplete. Planetary scientists interested in Ice Giant missions should perform mission design studies with these new Entry System technologies to assess the feasibility within the context of the international collaboration framework. A mission architecture that includes probe(s) along with an orbiting spacecraft can deploy the probes at the desired location while taking simultaneous measurements from orbit to provide invaluable data that can correlate both global and local measurements. Entry System Technologies currently being developed by NASA are poised to enable missions that position the Orbiter & Probes through drag modulated aerocapture (ADEPT), and HEEET enables the Probes to survive the extreme environments encountered for entry into the atmospheric interior.

Venkatapathy, E.↗
NASA NTRS1992

In situ stratospheric measurements of CH4, (C-13)H4, N2O, and OC(O-18) using the BLISS tunable diode laser spectrometer

Simultaneous in situ measurements of stratospheric CH4, (C-13)H4, N2O, OC(O-18), pressure, and temperature have been made from Palestine, Texas (32 deg N) in September 1988 with the JPL Balloon-borne Laser In Situ Sensor. Measurements of CH4 and N2O in the altitude range 30-35 km agree well with other measurements, except for an anomalously high value for the N2O at 31 km. Measurements of CH4 support earlier observations of fold in the vertical profile. A ratio for stratospheric (C-13)H4/CH4 of 0.0105 +/- 0.0010 implies an enrichment of delta(C-13) = -45 +/- 92 parts per thousand over the PDB value, in agreement with previous measurements in the troposphere. A large mixing ratio of 1.9 +/- 0.2 ppmv for OC(O-18) is measured, corresponding to an enrichment of delta(O-18) = 280 +/- 50 parts per thousand for the (O-18) isotopic species over the SMOW value.

Webster, Christopher R.↗
NASA NTRS1992

Intercomparisons of Lidar Backscatter Measurements and In-situ Data from GLOBE

The Global Backscatter Experiment (GLOBE) took place during Nov. 1989 and May - Jun. 1990 and involved flight surveys of the Pacific region by the NASA DC-8 aircraft. The experimental instruments were lidars operating at wavelengths ranging from the visible to the thermal infrared and various optical particle counters for in-situ measurements. The primary motivation for GLOBE was the development of spaceborne wind sensing lidar. This paper will concern a comparison of direct backscatter measurements and backscatter calculated from particle counter data. Of special interest is that the particle measurements provided data on composition, and thus refractive index variation may be included in the analysis.

Chudamani, S.↗
NASA NTRS2000

In-Situ Environmental Measurements Needed for Future Mars Missions

Existing measurements and modeling studies indicate that the climate and general circulation of the thin, predominately CO2 Martian atmosphere are characterized by large-amplitude variations with a wide range of spatial and temporal scales. Remote sensing observations from Earth-based telescopes and the Mariner 9, Viking, Phobos, and Mars Global Surveyor (MGS) orbiters show that the prevailing climate includes large-scale seasonal variations in surface and atmospheric temperatures (140 to 300 K), dust optical depth (0.15 to 1), and water vapor (10 to 100 precipitable microns). These observations also provided the first evidence for episodic regional and global dust storms that produce even larger perturbations in the atmospheric thermal structure and general circulation. In-situ measurements by the Viking and Mars Pathfinder Landers reinforced these conclusions, documenting changes in the atmospheric pressure on diurnal (5%) and seasonal (>20%) time scales, as well as large diurnal variations in the near-surface temperature (40 to 70 K), wind velocity (0 to 35 m/s), and dust optical depth (0.3 to 6). These in-situ measurements also reveal phenomena with temporal and spatial scales that cannot be resolved from orbit, including rapid changes in near-surface temperatures (+/- 10 K in 10 seconds), large near-surface vertical temperature gradients (+/- 15 K/meter), diurnally-varying slope winds, and dust devils . Modeling studies indicate that these changes are forced primarily by diurnal and seasonal variations in solar insolation, but they also include contributions from atmospheric thermal tides, baroclinic waves (fronts), Kelvin waves, slope winds, and monsoonal flows from the polar caps.

Crisp, D.↗
NASA NTRS1990

In situ ozone measurements for the airborne arctic stratospheric experiment

The research provided in-situ ozone measurements onboard the NASA Ames DC-8 research aircraft during the 1989 Airborne Arctic Stratospheric Experiment. The Ames DC-8 and ER-2 aircraft performed extensive sampling of the Arctic stratosphere and troposphere in a program designed to study those factors important in ozone depletion in the Arctic during times when the polar vortex and meteorology are conducive to the formation of polar stratospheric clouds and/or an Arctic ozone hole. The DC-8 ozone instrument complement included in-situ measurements for H2O, NO, NO2, NO(y) gas, NO(y) particulate, as well as remote sensors for measuring the vertical distribution and column density of ozone above the aircraft altitude. The in-situ data (ozone, water vapor, and nitrogen species) at the aircraft altitude provide a definition of tropospheric conditions in the vicinity of the polar vortex and polar stratospheric clouds. Defining tropospheric conditions will assist in the understanding of the chemistry of both stratosphere and troposphere and the extent to which polar stratospheric clouds affect the chemistry of transported air.

Gregory, Gerald L.↗
NASA NTRS1986

Comparison between S. T. radar and in situ balloon measurements

A campaign for simultaneous in situ and remote observation of both troposphere and stratosphere took place near Aire-sur-l'Adour (in southeastern France) on May 4, 1984. The aim of this campaign was a better understanding of the physics of radar echoes. The backscattered signal obtained with a stratosphere-troposphere radar both at the vertical and 15 deg. off vertical is compared with the velocity and temperature measurements made in the same region (about 10 km north of the radar site) by balloon-borne ionic anenometers and temperature sensors. In situ measurements clearly indicate that the temperature fluctuations are not always consistent with the standard turbulent theory. Nevertheless, the assumptions generally made (isotropy and turbulent field in k) and the classical formulation so derived for radar reflectivity are able to reproduce the shape of the radar return power profiles in oblique directions. Another significant result is the confirmation of the role played by the atmospheric stratification in the vertical echo power. It is important to develop these simultaneous in situ and remote experiments for a better description of the dynamical and thermal structure of the atmosphere and for a better understanding of the mechanisms governing clear-air radar reflectivity.

Dalaudier, F.↗
DOE OSTI2022

A Method for In-Situ Q₀ Measurements of High-Quality SRF Resonators

Accelerator projects such as LCLS-II naturally require low-loss superconducting (SRF) cavities. Due to strong demand for improving intrinsic quality factor (Q₀), importance of accurate cavity characterization increases. We propose a method to measure Q₀ in situ for an SRF resonator installed in its cryogenic module and connected with a RF feed source via a fixed RF coupler. The method exploits measurements of a response for an SRF resonator fed by an amplitude-modulated signal. Such a signal can be synthesized as a beat-wave composed of two frequencies that are close to the resonant frequency. Analyzing the envelope of the reflected signal, one can find the difference in reflection for the chosen frequencies and use them to compute the intrinsic Q. We also develop the methodology to carry out measurements of Q₀ at the nominal cavity operating voltage. We verified our method in experiments with a room temperature copper resonator and with two SRF resonators including Fermilab’s 650 MHz cavity and JLab’s 1500 MHz cavity.

43 PARTICLE ACCELERATORS↗