Sample records for absolute gravity stations

  1. Absolute-gravity stations in Western Dronning Maud Land, Antarctica

    NASA Astrophysics Data System (ADS)

    Mäkinen, Jaakko; Rasindra, Ravik; Chand, Uttam; Tiwari, Virendra; Lukin, Valery; Anisimov, Michail; Melvaer, Yngve; Melland, Gudmund; Koivula, Hannu; Näränen, Jyri; Poutanen, Markku

    2013-04-01

    Absolute-gravity stations are an important part of the geodetic infrastructure of the Antarctic. They provide accurate starting values for gravity surveys performed e.g. for the determination of the geoid, for geological studies and for geophysical investigations. The time variation in gravity determined from repeated absolute-gravity measurements provides insights into the Glacial Isostatic Adjustment (GIA) and into solid Earth deformation due to variation in contemporary ice load. Given sufficient joint coverage with International Terrestrial Reference Frame (ITRF) sites, gravity rates in high latitudes could in principle provide an independent check of the geocentricity of the z-dot (velocities in the direction of the rotation axis of the Earth) of the ITRF. We review the absolute gravity stations in Western and Central Dronning Maud Land. The oldest station is at the Finnish base Aboa, with 5 measurements by the Finnish Geodetic Institute (FGI) starting with the FINNARP 1993 expedition. Measurements at Maitri (India) and Novolazarevskaya (Russia) were first performed in 2004 by the National Geophysical Research Institute (NGRI) of India, and by the FGI, respectively. In the season 2010/11 a new station was constructed at Troll (Norway). In the season 2011/12 the aforementioned four sites were occupied by the FG5-221 absolute gravimeter of the FGI. At Sanae IV (South Africa) there are previous occupations by the FG5-221, in 2003/4 and 2005/6. All these bases have continuous GNSS stations. Numerous supporting measurements have been made at the sites: microgravity networks, levelling and GNSS ties to excentres etc., for controlling the stability of the stations. At some sites, nearby glacier elevations were surveyed to monitor the attraction of the variable close-field snow and ice masses. We give a description of the sites and the measurements performed at them. The work has benefited from the co-operation in the COST Action ES0701 "Improved Constraints on Models

  2. The Austrian absolute gravity base net: 27 years of spatial and temporal acquisition of gravity data

    NASA Astrophysics Data System (ADS)

    Ullrich, Christian; Ruess, Diethard

    2014-05-01

    Since 1987 the BEV (Federal Office of Metrology and Surveying) has been operating the absolute gravimeters JILAg-6 and FG5 which are used for basic measurements to determine or review fundamental gravity stations in Austria and abroad. Overall more than 70 absolute gravity stations were installed in Austria and neighbouring countries and some of them have been regularly monitored. A few stations are part of international projects like ECGN (European Combined Geodetic network) and UNIGRACE (Unification of Gravity System in Central and Eastern Europe). As a national metrology institute (NMI) the Metrology Service of the BEV maintains the national standards for the realisation of the legal units of measurement and ensures their international equivalence and recognition. Thus the BEV maintains the national standard for gravimetry in Austria, which is validated and confirmed by international comparisons. Since 1989 the Austrian absolute gravimeters participated seven times in the ICAG's (International Comparison of Absolute Gravimeters) at the BIPM in Paris and Luxemburg and as well participated three times at the ECAG (European Comparison of Absolute Gravimeters) in Luxemburg. The results of these ICAG's and especially the performance of the Austrian absolute gravimeter are reported in this presentation. We also present some examples and interpretation of long time monitoring stations of absolute gravity in several Austrian locations. Some stations are located in large cities like Vienna and Graz and some others are situated in mountainous regions. Mountain stations are at the Conrad Observatory where a SG (Superconducting Gravimeter) is permanently monitoring and in Obergurgl (Tyrolia) at an elevation of approx. 2000 m which is very strong influenced from the glacier retreat.

  3. New design and facilities for the International Database for Absolute Gravity Measurements (AGrav): A support for the Establishment of a new Global Absolute Gravity Reference System

    NASA Astrophysics Data System (ADS)

    Wziontek, Hartmut; Falk, Reinhard; Bonvalot, Sylvain; Rülke, Axel

    2017-04-01

    After about 10 years of successful joint operation by BGI and BKG, the International Database for Absolute Gravity Measurements "AGrav" (see references hereafter) was under a major revision. The outdated web interface was replaced by a responsive, high level web application framework based on Python and built on top of Pyramid. Functionality was added, like interactive time series plots or a report generator and the interactive map-based station overview was updated completely, comprising now clustering and the classification of stations. Furthermore, the database backend was migrated to PostgreSQL for better support of the application framework and long-term availability. As comparisons of absolute gravimeters (AG) become essential to realize a precise and uniform gravity standard, the database was extended to document the results on international and regional level, including those performed at monitoring stations equipped with SGs. By this it will be possible to link different AGs and to trace their equivalence back to the key comparisons under the auspices of International Committee for Weights and Measures (CIPM) as the best metrological realization of the absolute gravity standard. In this way the new AGrav database accommodates the demands of the new Global Absolute Gravity Reference System as recommended by the IAG Resolution No. 2 adopted in Prague 2015. The new database will be presented with focus on the new user interface and new functionality, calling all institutions involved in absolute gravimetry to participate and contribute with their information to built up a most complete picture of high precision absolute gravimetry and improve its visibility. A Digital Object Identifier (DOI) will be provided by BGI to contributors to give a better traceability and facilitate the referencing of their gravity surveys. Links and references: BGI mirror site : http://bgi.obs-mip.fr/data-products/Gravity-Databases/Absolute-Gravity-data/ BKG mirror site: http

  4. Differential results integrated with continuous and discrete gravity measurements between nearby stations

    NASA Astrophysics Data System (ADS)

    Xu, Weimin; Chen, Shi; Lu, Hongyan

    2016-04-01

    Integrated gravity is an efficient way in studying spatial and temporal characteristics of the dynamics and tectonics. Differential measurements based on the continuous and discrete gravity observations shows highly competitive in terms of both efficiency and precision with single result. The differential continuous gravity variation between the nearby stations, which is based on the observation of Scintrex g-Phone relative gravimeters in every single station. It is combined with the repeated mobile relative measurements or absolute results to study the regional integrated gravity changes. Firstly we preprocess the continuous records by Tsoft software, and calculate the theoretical earth tides and ocean tides by "MT80TW" program through high precision tidal parameters from "WPARICET". The atmospheric loading effects and complex drift are strictly considered in the procedure. Through above steps we get the continuous gravity in every station and we can calculate the continuous gravity variation between nearby stations, which is called the differential continuous gravity changes. Then the differential results between related stations is calculated based on the repeated gravity measurements, which are carried out once or twice every year surrounding the gravity stations. Hence we get the discrete gravity results between the nearby stations. Finally, the continuous and discrete gravity results are combined in the same related stations, including the absolute gravity results if necessary, to get the regional integrated gravity changes. This differential gravity results is more accurate and effective in dynamical monitoring, regional hydrologic effects studying, tectonic activity and other geodynamical researches. The time-frequency characteristics of continuous gravity results are discussed to insure the accuracy and efficiency in the procedure.

  5. Repeat Absolute and Relative Gravity Measurements for Geothermal Reservoir Monitoring in the Ogiri Geothermal Field, Southern Kyushu, Japan

    NASA Astrophysics Data System (ADS)

    Nishijima, J.; Umeda, C.; Fujimitsu, Y.; Takayama, J.; Hiraga, N.; Higuchi, S.

    2016-09-01

    Repeat hybrid microgravity measurements were conducted around the Ogiri Geothermal Field on the western slope of Kirishima volcano, southern Kyushu, Japan. This study was undertaken to detect the short-term gravity change caused by the temporary shutdown of production and reinjection wells for regular maintenance in 2011 and 2013. Repeat microgravity measurements were taken using an A-10 absolute gravimeter (Micro-g LaCoste) and CG-5 gravimeter (Scintrex) before and after regular maintenance. Both instruments had an accuracy of 10 μgal. The gravity stations were established at 27 stations (two stations for absolute measurements and 25 stations for relative measurements). After removal of noise effects (e.g., tidal movement, precipitation, shallow groundwater level changes), the residual gravity changes were subdivided into five types of response. We detected a gravity decrease (up to 20 μgal) in the reinjection area and a gravity increase (up to 30 μgal) in the production area 1 month after the temporary shutdown. Most of the gravity stations recovered after the maintenance. The temporal density changes in the geothermal reservoir were estimated based on these gravity changes.

  6. Linking Comparisons of Absolute Gravimeters: A Proof of Concept for a new Global Absolute Gravity Reference System.

    NASA Astrophysics Data System (ADS)

    Wziontek, H.; Palinkas, V.; Falk, R.; Vaľko, M.

    2016-12-01

    Since decades, absolute gravimeters are compared on a regular basis on an international level, starting at the International Bureau for Weights and Measures (BIPM) in 1981. Usually, these comparisons are based on constant reference values deduced from all accepted measurements acquired during the comparison period. Temporal changes between comparison epochs are usually not considered. Resolution No. 2, adopted by IAG during the IUGG General Assembly in Prague 2015, initiates the establishment of a Global Absolute Gravity Reference System based on key comparisons of absolute gravimeters (AG) under the International Committee for Weights and Measures (CIPM) in order to establish a common level in the microGal range. A stable and unique reference frame can only be achieved, if different AG are taking part in different kind of comparisons. Systematic deviations between the respective comparison reference values can be detected, if the AG can be considered stable over time. The continuous operation of superconducting gravimeters (SG) on selected stations further supports the temporal link of comparison reference values by establishing a reference function over time. By a homogenous reprocessing of different comparison epochs and including AG and SG time series at selected stations, links between several comparisons will be established and temporal comparison reference functions will be derived. By this, comparisons on a regional level can be traced to back to the level of key comparisons, providing a reference for other absolute gravimeters. It will be proved and discussed, how such a concept can be used to support the future absolute gravity reference system.

  7. Measured and modelled absolute gravity in Greenland

    NASA Astrophysics Data System (ADS)

    Nielsen, E.; Forsberg, R.; Strykowski, G.

    2012-12-01

    Present day changes in the ice volume in glaciated areas like Greenland will change the load on the Earth and to this change the lithosphere will respond elastically. The Earth also responds to changes in the ice volume over a millennial time scale. This response is due to the viscous properties of the mantle and is known as Glaical Isostatic Adjustment (GIA). Both signals are present in GPS and absolute gravity (AG) measurements and they will give an uncertainty in mass balance estimates calculated from these data types. It is possible to separate the two signals if both gravity and Global Positioning System (GPS) time series are available. DTU Space acquired an A10 absolute gravimeter in 2008. One purpose of this instrument is to establish AG time series in Greenland and the first measurements were conducted in 2009. Since then are 18 different Greenland GPS Network (GNET) stations visited and six of these are visited more then once. The gravity signal consists of three signals; the elastic signal, the viscous signal and the direct attraction from the ice masses. All of these signals can be modelled using various techniques. The viscous signal is modelled by solving the Sea Level Equation with an appropriate ice history and Earth model. The free code SELEN is used for this. The elastic signal is modelled as a convolution of the elastic Greens function for gravity and a model of present day ice mass changes. The direct attraction is the same as the Newtonian attraction and is calculated as this. Here we will present the preliminary results of the AG measurements in Greenland. We will also present modelled estimates of the direct attraction, the elastic and the viscous signals.

  8. Absolute gravity measurements in California

    NASA Astrophysics Data System (ADS)

    Zumberge, M. A.; Sasagawa, G.; Kappus, M.

    1986-08-01

    An absolute gravity meter that determines the local gravitational acceleration by timing a freely falling mass with a laser interferometer has been constructed. The instrument has made measurements at 11 sites in California, four in Nevada, and one in France. The uncertainty in the results is typically 10 microgal. Repeated measurements have been made at several of the sites; only one shows a substantial change in gravity.

  9. Measurement of absolute gravity acceleration in Firenze

    NASA Astrophysics Data System (ADS)

    de Angelis, M.; Greco, F.; Pistorio, A.; Poli, N.; Prevedelli, M.; Saccorotti, G.; Sorrentino, F.; Tino, G. M.

    2011-01-01

    This paper reports the results from the accurate measurement of the acceleration of gravity g taken at two separate premises in the Polo Scientifico of the University of Firenze (Italy). In these laboratories, two separate experiments aiming at measuring the Newtonian constant and testing the Newtonian law at short distances are in progress. Both experiments require an independent knowledge on the local value of g. The only available datum, pertaining to the italian zero-order gravity network, was taken more than 20 years ago at a distance of more than 60 km from the study site. Gravity measurements were conducted using an FG5 absolute gravimeter, and accompanied by seismic recordings for evaluating the noise condition at the site. The absolute accelerations of gravity at the two laboratories are (980 492 160.6 ± 4.0) μGal and (980 492 048.3 ± 3.0) μGal for the European Laboratory for Non-Linear Spectroscopy (LENS) and Dipartimento di Fisica e Astronomia, respectively. Other than for the two referenced experiments, the data here presented will serve as a benchmark for any future study requiring an accurate knowledge of the absolute value of the acceleration of gravity in the study region.

  10. A highly accurate absolute gravimetric network for Albania, Kosovo and Montenegro

    NASA Astrophysics Data System (ADS)

    Ullrich, Christian; Ruess, Diethard; Butta, Hubert; Qirko, Kristaq; Pavicevic, Bozidar; Murat, Meha

    2016-04-01

    The objective of this project is to establish a basic gravity network in Albania, Kosovo and Montenegro to enable further investigations in geodetic and geophysical issues. Therefore the first time in history absolute gravity measurements were performed in these countries. The Norwegian mapping authority Kartverket is assisting the national mapping authorities in Kosovo (KCA) (Kosovo Cadastral Agency - Agjencia Kadastrale e Kosovës), Albania (ASIG) (Autoriteti Shtetëror i Informacionit Gjeohapësinor) and in Montenegro (REA) (Real Estate Administration of Montenegro - Uprava za nekretnine Crne Gore) in improving the geodetic frameworks. The gravity measurements are funded by Kartverket. The absolute gravimetric measurements were performed from BEV (Federal Office of Metrology and Surveying) with the absolute gravimeter FG5-242. As a national metrology institute (NMI) the Metrology Service of the BEV maintains the national standards for the realisation of the legal units of measurement and ensures their international equivalence and recognition. Laser and clock of the absolute gravimeter were calibrated before and after the measurements. The absolute gravimetric survey was carried out from September to October 2015. Finally all 8 scheduled stations were successfully measured: there are three stations located in Montenegro, two stations in Kosovo and three stations in Albania. The stations are distributed over the countries to establish a gravity network for each country. The vertical gradients were measured at all 8 stations with the relative gravimeter Scintrex CG5. The high class quality of some absolute gravity stations can be used for gravity monitoring activities in future. The measurement uncertainties of the absolute gravity measurements range around 2.5 micro Gal at all stations (1 microgal = 10-8 m/s2). In Montenegro the large gravity difference of 200 MilliGal between station Zabljak and Podgorica can be even used for calibration of relative gravimeters

  11. Absolute Gravity Datum in the Age of Cold Atom Gravimeters

    NASA Astrophysics Data System (ADS)

    Childers, V. A.; Eckl, M. C.

    2014-12-01

    The international gravity datum is defined today by the International Gravity Standardization Net of 1971 (IGSN-71). The data supporting this network was measured in the 1950s and 60s using pendulum and spring-based gravimeter ties (plus some new ballistic absolute meters) to replace the prior protocol of referencing all gravity values to the earlier Potsdam value. Since this time, gravimeter technology has advanced significantly with the development and refinement of the FG-5 (the current standard of the industry) and again with the soon-to-be-available cold atom interferometric absolute gravimeters. This latest development is anticipated to provide improvement in the range of two orders of magnitude as compared to the measurement accuracy of technology utilized to develop ISGN-71. In this presentation, we will explore how the IGSN-71 might best be "modernized" given today's requirements and available instruments and resources. The National Geodetic Survey (NGS), along with other relevant US Government agencies, is concerned about establishing gravity control to establish and maintain high order geodetic networks as part of the nation's essential infrastructure. The need to modernize the nation's geodetic infrastructure was highlighted in "Precise Geodetic Infrastructure, National Requirements for a Shared Resource" National Academy of Science, 2010. The NGS mission, as dictated by Congress, is to establish and maintain the National Spatial Reference System, which includes gravity measurements. Absolute gravimeters measure the total gravity field directly and do not involve ties to other measurements. Periodic "intercomparisons" of multiple absolute gravimeters at reference gravity sites are used to constrain the behavior of the instruments to ensure that each would yield reasonably similar measurements of the same location (i.e. yield a sufficiently consistent datum when measured in disparate locales). New atomic interferometric gravimeters promise a significant

  12. Results from a U.S. Absolute Gravity Survey,

    DTIC Science & Technology

    1982-01-01

    National Bureau of Standards. La . ... ,., 831A08 NOV -2- 1. Introduction We have recently completed an absolute gravity survey at twelve sites in the...Air Force Geophysics Laboratory (AFGL) and the Istituto di Metrologia -7- "G. Colonnetti" (IMGC) [Marson and Alasia, 1978, 19801. All three...for ab- solute measurements of the earth’s gravity, Metrologia , in press, 1982. L 4 !" Table 1. Gravity values transferred to the floor in gal (cm

  13. Gravity data from the San Pedro River Basin, Cochise County, Arizona

    USGS Publications Warehouse

    Kennedy, Jeffrey R.; Winester, Daniel

    2011-01-01

    The U.S. Geological Survey, Arizona Water Science Center in cooperation with the National Oceanic and Atmospheric Administration, National Geodetic Survey has collected relative and absolute gravity data at 321 stations in the San Pedro River Basin of southeastern Arizona since 2000. Data are of three types: observed gravity values and associated free-air, simple Bouguer, and complete Bouguer anomaly values, useful for subsurface-density modeling; high-precision relative-gravity surveys repeated over time, useful for aquifer-storage-change monitoring; and absolute-gravity values, useful as base stations for relative-gravity surveys and for monitoring gravity change over time. The data are compiled, without interpretation, in three spreadsheet files. Gravity values, GPS locations, and driving directions for absolute-gravity base stations are presented as National Geodetic Survey site descriptions.

  14. Gravity data from the Sierra Vista Subwatershed, Upper San Pedro Basin, Arizona

    USGS Publications Warehouse

    Kennedy, Jeffrey R.

    2015-01-01

    This report (1) summarizes changes to the Sierra Vista Subwatershed regional time-lapse gravity network with respect to station locations and (2) presents 2014 and 2015 gravity measurements and gravity values at each station. A prior gravity network, established between 2000 and 2005, was revised in 2014 to cover a larger number of stations over a smaller geographic area in order to decrease measurement and interpolation uncertainty. The network currently consists of 59 gravity stations, including 14 absolute-gravity stations. Following above-average rainfall during summer 2014, gravity increased at all but one of the absolute-gravity stations that were observed in both June 2014 and January 2015. This increase in gravity indicates increased groundwater storage in the aquifer and (or) unsaturated zone as a result of rainfall and infiltration.

  15. Use of Absolute Gravity Measurements to Monitor Groundwater in the Española Basin, New Mexico

    NASA Astrophysics Data System (ADS)

    Cogbill, A. H.; Ferguson, J. F.; Keating, E. H.

    2005-05-01

    We present early results of three-year project using absolute gravity instrumentation to monitor groundwater in an arid to semi-arid region in northern New Mexico. Over 100 permanent gravity stations have been established in the groundwater basin. A-10 absolute gravity meters, manufactured by Micro-g Solutions, Inc., have been used to monitor long-term gravity changes in the groundwater basin. Over fifty A-10 sites have been established; other gravity sites have been established by reference to the primary A-10 sites using Scintrex CG-3M relative gravimeters. We have used geodetic-quality GPS surveys to directly measure any possible elevation changes at the gravity sites; thus far, no significant changes in elevation have been observed. For the A-10 gravity sites, we have learned that sites must be constructed rather carefully to minimize noise levels due to certain characteristics of the A-10 measurement system. At good sites, away from regions where we expect changes due to groundwater removal, reproducibility of the A-10 measurements is ±4~μGal. To date, we have data from repeat campaigns over a period of 22 months. We have observed systematic changes in gravity of as much as 14~μGal at certain sites. We have directly incorporated gravity modeling into a detailed 3D groundwater model of the basin. On the basis of groundwater modeling, we believe that such gravity changes are due to increased recharge at some sites, as precipitation began to return to normal amounts after a long, pronounced drought about a year into the study. Somewhat surprisingly, no significant gravity changes have been observed at the Buckman Well Field, a spatially small well field that is heavily pumped as a municipal supply field for Santa Fe, New Mexico. One interpretation of this observation is that pumping at the Buckman Field is accessing nearby surface sources rather than groundwater, despite the fact that pumping is occurring from more than 300~m depth.

  16. The JILA (Joint Institute for Laboratory Astrophysics) portable absolute gravity apparatus

    NASA Astrophysics Data System (ADS)

    Faller, J. E.; Guo, Y. G.; Gschwind, J.; Niebauer, T. M.; Rinker, R. L.; Xue, J.

    1983-08-01

    We have developed a new and highly portable absolute gravity apparatus based on the principles of free-fall laser interferometry. A primary concern over the past several years has been the detection, understanding, and elimination of systematic errors. In the Spring of 1982, we used this instrument to carry out a survey at twelve sites in the United States. Over a period of eight weeks, the instrument was driven a distance of nearly 20,000 km to sites in California, New Mexico, Colorado, Wyoming, Maryland, and Massachusetts. The time required to carry out a measurement at each location was typically one day. Over the next several years, our intention is to see absolute gravity measurements become both usable and used in the field. To this end, and in the context of cooperative research programs with a number of scientific institutes throughout the world, we are building additional instruments (incorporating further refinements) which are to be used for geodetic, geophysical, geological, and tectonic studies. With these new instruments we expect to improve (perhaps by a factor of two) on the 6-10 microgal accuracy of our present instrument. Today, one can make absolutely gravity measurements as accurately as - possibly even more accurately than - one can make relative measurements. Given reasonable success with the new instruments in the field, the last years of this century should see absolute gravity measurement mature both as a new geodetic data type and as a useful geophysical tool.

  17. Establishment of National Gravity Base Network of Iran

    NASA Astrophysics Data System (ADS)

    Hatam Chavari, Y.; Bayer, R.; Hinderer, J.; Ghazavi, K.; Sedighi, M.; Luck, B.; Djamour, Y.; Le Moign, N.; Saadat, R.; Cheraghi, H.

    2009-04-01

    A gravity base network is supposed to be a set of benchmarks uniformly distributed across the country and the absolute gravity values at the benchmarks are known to the best accessible accuracy. The gravity at the benchmark stations are either measured directly with absolute devices or transferred by gravity difference measurements by gravimeters from known stations. To decrease the accumulation of random measuring errors arising from these transfers, the number of base stations distributed across the country should be as small as possible. This is feasible if the stations are selected near to the national airports long distances apart but faster accessible and measurable by a gravimeter carried in an airplane between the stations. To realize the importance of such a network, various applications of a gravity base network are firstly reviewed. A gravity base network is the required reference frame for establishing 1st , 2nd and 3rd order gravity networks. Such a gravity network is used for the following purposes: a. Mapping of the structure of upper crust in geology maps. The required accuracy for the measured gravity values is about 0.2 to 0.4 mGal. b. Oil and mineral explorations. The required accuracy for the measured gravity values is about 5 µGal. c. Geotechnical studies in mining areas for exploring the underground cavities as well as archeological studies. The required accuracy is about 5 µGal and better. d. Subsurface water resource explorations and mapping crustal layers which absorb it. An accuracy of the same level of previous applications is required here too. e. Studying the tectonics of the Earth's crust. Repeated precise gravity measurements at the gravity network stations can assist us in identifying systematic height changes. The accuracy of the order of 5 µGal and more is required. f. Studying volcanoes and their evolution. Repeated precise gravity measurements at the gravity network stations can provide valuable information on the gradual

  18. Absolute gravimetry for monitoring geodynamics in Greenland.

    NASA Astrophysics Data System (ADS)

    Nielsen, E.; Strykowski, G.; Forsberg, R.

    2015-12-01

    Here are presented the preliminary results of the absolute gravity measurements done in Greenland by DTU Space with their A10 absolute gravimeter (the A10-019). The purpose, besides establishing and maintaining a national gravity network, is to study geodynamics.The absolute gravity measurements are juxtaposed with the permanent GNET GNSS stations. The first measurements were conducted in 2009 and a few sites have been re-visited. As of present is there a gravity value at 18 GNET sites.There are challenges in interpreting the measurements from Greenland and several signals has to be taken into account, besides the geodynamical signals originating from the changing load of the ice, there is also a clear signal of direct attraction from different masses. Here are presented the preliminary results of our measurements in Greenland and attempts explain them through modelling of the geodynamical signals and the direct attraction from the ocean and ice.

  19. Integrating stations from the North America Gravity Database into a local GPS-based land gravity survey

    USGS Publications Warehouse

    Shoberg, Thomas G.; Stoddard, Paul R.

    2013-01-01

    The ability to augment local gravity surveys with additional gravity stations from easily accessible national databases can greatly increase the areal coverage and spatial resolution of a survey. It is, however, necessary to integrate such data seamlessly with the local survey. One challenge to overcome in integrating data from national databases is that these data are typically of unknown quality. This study presents a procedure for the evaluation and seamless integration of gravity data of unknown quality from a national database with data from a local Global Positioning System (GPS)-based survey. The starting components include the latitude, longitude, elevation and observed gravity at each station location. Interpolated surfaces of the complete Bouguer anomaly are used as a means of quality control and comparison. The result is an integrated dataset of varying quality with many stations having GPS accuracy and other reliable stations of unknown origin, yielding a wider coverage and greater spatial resolution than either survey alone.

  20. Improvements in absolute seismometer sensitivity calibration using local earth gravity measurements

    USGS Publications Warehouse

    Anthony, Robert E.; Ringler, Adam; Wilson, David

    2018-01-01

    The ability to determine both absolute and relative seismic amplitudes is fundamentally limited by the accuracy and precision with which scientists are able to calibrate seismometer sensitivities and characterize their response. Currently, across the Global Seismic Network (GSN), errors in midband sensitivity exceed 3% at the 95% confidence interval and are the least‐constrained response parameter in seismic recording systems. We explore a new methodology utilizing precise absolute Earth gravity measurements to determine the midband sensitivity of seismic instruments. We first determine the absolute sensitivity of Kinemetrics EpiSensor accelerometers to 0.06% at the 99% confidence interval by inverting them in a known gravity field at the Albuquerque Seismological Laboratory (ASL). After the accelerometer is calibrated, we install it in its normal configuration next to broadband seismometers and subject the sensors to identical ground motions to perform relative calibrations of the broadband sensors. Using this technique, we are able to determine the absolute midband sensitivity of the vertical components of Nanometrics Trillium Compact seismometers to within 0.11% and Streckeisen STS‐2 seismometers to within 0.14% at the 99% confidence interval. The technique enables absolute calibrations from first principles that are traceable to National Institute of Standards and Technology (NIST) measurements while providing nearly an order of magnitude more precision than step‐table calibrations.

  1. Principal facts for 408 gravity stations in the vicinity of the Talkeetna Mountains, south-central Alaska

    USGS Publications Warehouse

    Morin, Robert L.; Glen, Jonathan M.G.

    2003-01-01

    Gravity data were collected between 1999 and 2002 along transects in the Talkeetna Mountains of south-central Alaska as part of a geological and geophysical study of the framework geology of the region. The study area lies between 61° 30’ and 63° 45’ N. latitude and 145° and 151° W. longitude. This data set includes 408 gravity stations. These data, combined with the pre-existing 3,286 stations, brings the total data in this area to 3,694 gravity stations. Principal facts for the 408 new gravity stations and the 15 gravity base stations used for control are listed in this report. During the summer of 1999, a gravity survey was conducted in the western Talkeetna Mountains. Measurements at 55 gravity stations were made. One gravity base station was used for control for this survey. This base station, STEP, is located at the Stephan Lake Lodge on Stephan Lake. The observed gravity of this station was calculated based on an indirect tie to base station ANCL in Anchorage. The temporary base used to tie between STEP and ANCL was REGL in Anchorage. During the summer of 2000, a gravity survey was conducted in the western Talkeetna Mountains. Measurements at 56 gravity stations were made. One gravity base station was used for control for this survey. This base station, GRHS, is located at the Gracious House Lodge on the Denali Highway. The observed gravity of this station was calculated based on multiple ties to base stations D87, and D57 along the Denali Highway. During the summer of 2001, a gravity survey was conducted in the western Talkeetna Mountains. Measurements at 90 gravity stations were made. One gravity base station was used for control for this survey. This base station, HLML, is located at the High Lake Lodge. The observed gravity of this station was calculated based on multiple ties to base stations ANCU in Anchorage, PALH in Palmer, WASA in Wasilla, and TLKM in Talkeetna. Also during the summer of 2001, a gravity survey was conducted in the vicinity

  2. Data reduction and tying in regional gravity surveys—results from a new gravity base station network and the Bouguer gravity anomaly map for northeastern Mexico

    NASA Astrophysics Data System (ADS)

    Hurtado-Cardador, Manuel; Urrutia-Fucugauchi, Jaime

    2006-12-01

    Since 1947 Petroleos Mexicanos (Pemex) has conducted oil exploration projects using potential field methods. Geophysical exploration companies under contracts with Pemex carried out gravity anomaly surveys that were referred to different floating data. Each survey comprises observations of gravity stations along highways, roads and trails at intervals of about 500 m. At present, 265 separate gravimeter surveys that cover 60% of the Mexican territory (mainly in the oil producing regions of Mexico) are available. This gravity database represents the largest, highest spatial resolution information, and consequently has been used in the geophysical data compilations for the Mexico and North America gravity anomaly maps. Regional integration of gravimeter surveys generates gradients and spurious anomalies in the Bouguer anomaly maps at the boundaries of the connected surveys due to the different gravity base stations utilized. The main objective of this study is to refer all gravimeter surveys from Pemex to a single new first-order gravity base station network, in order to eliminate problems of gradients and spurious anomalies. A second objective is to establish a network of permanent gravity base stations (BGP), referred to a single base from the World Gravity System. Four regional loops of BGP covering eight States of Mexico were established to support the tie of local gravity base stations from each of the gravimeter surveys located in the vicinity of these loops. The third objective is to add the gravity constants, measured and calculated, for each of the 265 gravimeter surveys to their corresponding files in the Pemex and Instituto Mexicano del Petroleo database. The gravity base used as the common datum is the station SILAG 9135-49 (Latin American System of Gravity) located in the National Observatory of Tacubaya in Mexico City. We present the results of the installation of a new gravity base network in northeastern Mexico, reference of the 43 gravimeter surveys

  3. Gsolve, a Python computer program with a graphical user interface to transform relative gravity survey measurements to absolute gravity values and gravity anomalies

    NASA Astrophysics Data System (ADS)

    McCubbine, Jack; Tontini, Fabio Caratori; Stagpoole, Vaughan; Smith, Euan; O'Brien, Grant

    2018-01-01

    A Python program (Gsolve) with a graphical user interface has been developed to assist with routine data processing of relative gravity measurements. Gsolve calculates the gravity at each measurement site of a relative gravity survey, which is referenced to at least one known gravity value. The tidal effects of the sun and moon, gravimeter drift and tares in the data are all accounted for during the processing of the survey measurements. The calculation is based on a least squares formulation where the difference between the absolute gravity at each surveyed location and parameters relating to the dynamics of the gravimeter are minimized with respect to the relative gravity observations, and some supplied gravity reference site values. The program additionally allows the user to compute free air gravity anomalies, with respect to the GRS80 and GRS67 reference ellipsoids, from the determined gravity values and calculate terrain corrections at each of the surveyed sites using a prism formula and a user supplied digital elevation model. This paper reviews the mathematical framework used to reduce relative gravimeter survey observations to gravity values. It then goes on to detail how the processing steps can be implemented using the software.

  4. Results from a U.S. absolute gravity survey

    NASA Astrophysics Data System (ADS)

    Zumberge, M. A.; Faller, J. E.; Gschwind, J.

    Using the recently completed JILA absolute gravity meter, we made a survey of twelve sites in the United States. Over a period of eight weeks, the instrument was driven a total distance of nearly 20,000 km to sites in California, New Mexico, Colorado, Wyoming, Maryland and Massachusetts. The time spent in carrying out a measurement at a single location was typically one day. We report the results of the measurements in this survey along with earlier measurements made with the instrument, discuss the measurement accuracy and compare our results with other measurements.

  5. The use of absolute gravity data for the validation of Global Geopotential Models and for improving quasigeoid heights determined from satellite-only Global Geopotential Models

    NASA Astrophysics Data System (ADS)

    Godah, Walyeldeen; Krynski, Jan; Szelachowska, Malgorzata

    2018-05-01

    The objective of this paper is to demonstrate the usefulness of absolute gravity data for the validation of Global Geopotential Models (GGMs). It is also aimed at improving quasigeoid heights determined from satellite-only GGMs using absolute gravity data. The area of Poland, as a unique one, covered with a homogeneously distributed set of absolute gravity data, has been selected as a study area. The gravity anomalies obtained from GGMs were validated using the corresponding ones determined from absolute gravity data. The spectral enhancement method was implemented to overcome the spectral inconsistency in data being validated. The quasigeoid heights obtained from the satellite-only GGM as well as from the satellite-only GGM in combination with absolute gravity data were evaluated with high accuracy GNSS/levelling data. Estimated accuracy of gravity anomalies obtained from GGMs investigated is of 1.7 mGal. Considering omitted gravity signal, e.g. from degree and order 101 to 2190, satellite-only GGMs can be validated at the accuracy level of 1 mGal using absolute gravity data. An improvement up to 59% in the accuracy of quasigeoid heights obtained from the satellite-only GGM can be observed when combining the satellite-only GGM with absolute gravity data.

  6. Principal facts of gravity stations with gravity and magnetic profiles from the Southwest Nevada Test Site, Nye County, Nevada, as of January, 1982

    USGS Publications Warehouse

    Jansma, P.E.; Snyder, D.B.; Ponce, David A.

    1983-01-01

    Three gravity profiles and principal facts of 2,604 gravity stations in the southwest quadrant of the Nevada Test Site are documented in this data report. The residual gravity profiles show the gravity measurements and the smoothed curves derived from these points that were used in geophysical interpretations. The principal facts include station label, latitude, longitude, elevation, observed gravity value, and terrain correction for each station as well as the derived complete Bouguer and isostatic anomalies, reduced at 2.67 g/cm 3. Accuracy codes, where available, further document the data.

  7. Evaluation of global satellite gravity models using terrestrial gravity observations over the Kingdom of Saudi Arabia A. Alothman and B. Elsaka

    NASA Astrophysics Data System (ADS)

    Alothman, Abdulaziz; Elsaka, Basem

    The gravity field models from the GRACE and GOCE missions have increased the knowledge of the earth’s global gravity field. The latter GOCE mission has provided accuracies of about 1-2 cm and 1milli-Gal level in the global geoid and gravity anomaly, respectively. However, determining all wavelength ranges of the gravity field spectrum cannot be only achieved from satellite gravimetry but from the allowed terrestrial gravity data. In this contribution, we use a gravity network of 42 first-order absolute gravity stations, observed by LaCosta Romberg gravimeter during the period 1967-1969 by Ministry of Petroleum and Mineral Resources, to validate the GOCE gravity models in order to gain more detailed regional gravity information. The network stations are randomly distributed all over the country with a spacing of about 200 km apart. The results show that the geoid height and gravity anomaly determined from terrestrial gravity data agree with the GOCE based models and give additional information to the satellite gravity solutions.

  8. Isostatic gravity map and principal facts for 694 gravity stations in Yellowstone National Park and vicinity, Wyoming, Montana, and Idaho

    USGS Publications Warehouse

    Carle, S.F.; Glen, J.M.; Langenheim, V.E.; Smith, R.B.; Oliver, H.W.

    1990-01-01

    The report presents the principal facts for gravity stations compiled for Yellowstone National Park and vicinity. The gravity data were compiled from three sources: Defense Mapping Agency, University of Utah, and U.S. Geological Survey. Part A of the report is a paper copy describing how the compilation was done and presenting the data in tabular format as well as a map; part B is a 5-1/4 inch floppy diskette containing only the data files in ASCII format. Requirements for part B: IBM PC or compatible, DOS v. 2.0 or higher. Files contained on this diskette: DOD.ISO -- File containing the principal facts of the 514 gravity stations obtained from the Defense Mapping Agency. The data are in Plouff format* (see file PFTAB.TEX). UTAH.ISO -- File containing the principal facts of 153 gravity stations obtained from the University of Utah. Data are in Plouff format. USGS.ISO -- File containing the principal facts of 27 gravity stations collected by the U.S. Geological Survey in July 1987. Data are in Plouff format. PFTAB.TXT -- File containing explanation of principal fact format. ACC.TXT -- File containing explanation of accuracy codes.

  9. Principal Facts for 463 Gravity Stations in the Vicinity of Tangle Lakes, East-Central Alaska

    USGS Publications Warehouse

    Morin, Robert L.; Glen, Jonathan M.G.

    2002-01-01

    During the summer of 2001, a gravity survey was conducted in the vicinity of Tangle Lakes, east-central Alaska. Measurements of 87 gravity stations were made. The Tangle Lakes area is located about 25 km west of Paxson and north of the Denali Highway. The gravity survey is located on the southwest corner of the Mt. Hayes and the northwest corner of the Gulkana 1:250,000 scale USGS topographic maps. The boundaries of the study area are 62 deg 30' to 63 deg 30' N. latitude and 145 deg 30' to 147 deg 00' W. longitude. A map showing the location of the study area is shown in figure 1. One gravity base station was used for control for this survey. This base station, TLIN is located at the Tangle Lakes Inn. The observed gravity of this station was calculated based on multiple ties to base stations ANCU in Anchorage, PALH in Palmer, BD27 in Gulkana, and base stations D42, and D57 along the Denali Highway.

  10. Fiber-optic extrinsic Fabry-Perot vibration-isolated interferometer for use in absolute gravity meters.

    PubMed

    Canuteson, E L; Zumberge, M

    1996-07-01

    In an absolute gravity meter, a laser interferometer measures the position of a test mass that is falling ina vacuum. The calculated value of gravity is the average acceleration of the mass during a set ofdrops. Since systematic accelerations of the optical system will bias the measured value of gravity,various interferometer geometries have been implemented in the past to isolate the optical system fromground motion. We have developed and tested a low-finesse fiber-optic extrinsic Fabry-Perotinterferometer that is fixed to the mass of a critically damped seismometer in which the effects ofsystematic ground motion and acoustic vibrations are reduced.

  11. The AFGL (Air Force Geophysics Laboratory) Absolute Gravity System’s Error Budget Revisted.

    DTIC Science & Technology

    1985-05-08

    also be induced by equipment not associated with the system. A systematic bias of 68 pgal was observed by the Istituto di Metrologia "G. Colonnetti...Laboratory Astrophysics, Univ. of Colo., Boulder, Colo. IMGC: Istituto di Metrologia "G. Colonnetti", Torino, Italy Table 1. Absolute Gravity Values...measurements were made with three Model D and three Model G La Coste-Romberg gravity meters. These instruments were operated by the following agencies

  12. Using absolute gravimeter data to determine vertical gravity gradients

    USGS Publications Warehouse

    Robertson, D.S.

    2001-01-01

    The position versus time data from a free-fall absolute gravimeter can be used to estimate the vertical gravity gradient in addition to the gravity value itself. Hipkin has reported success in estimating the vertical gradient value using a data set of unusually good quality. This paper explores techniques that may be applicable to a broader class of data that may be contaminated with "system response" errors of larger magnitude than were evident in the data used by Hipkin. This system response function is usually modelled as a sum of exponentially decaying sinusoidal components. The technique employed here involves combining the x0, v0 and g parameters from all the drops made during a site occupation into a single least-squares solution, and including the value of the vertical gradient and the coefficients of system response function in the same solution. The resulting non-linear equations must be solved iteratively and convergence presents some difficulties. Sparse matrix techniques are used to make the least-squares problem computationally tractable.

  13. Principal facts for gravity stations in the Antelope Valley-Bedell Flat area, west-central Nevada

    USGS Publications Warehouse

    Jewel, Eleanore B.; Ponce, David A.; Morin, Robert L.

    2000-01-01

    In April 2000 the U.S. Geological Survey (USGS) established 211 gravity stations in the Antelope Valley and Bedell Flat area of west-central Nevada (see figure 1). The stations were located about 15 miles north of Reno, Nevada, southwest of Dogskin Mountain, and east of Petersen Mountain, concentrated in Antelope Valley and Bedell Flat (figure 2). The ranges in this area primarily consist of normal-faulted Cretaceous granitic rocks, with some volcanic and metavolcanic rocks. The purpose of the survey was to characterize the hydrogeologic framework of Antelope Valley and Bedell Flat in support of future hydrologic investigations. The information developed during this study can be used in groundwater models. Gravity data were collected between latitude 39°37.5' and 40°00' N and longitude 119°37.5' and 120°00' W. The stations were located on the Seven Lakes Mountain, Dogskin Mountain, Granite Peak, Bedell Flat, Fraser Flat, and Reno NE 7.5 minute quadrangles. All data were tied to secondary base station RENO-A located on the campus of the University of Nevada at Reno (UNR) in Reno, Nevada (latitude 39°32.30' N, longitude 119°48.70' W, observed gravity value 979674.69 mGal). The value for observed gravity was calculated by multiple ties to the base station RENO (latitude 39°32.30' N, longitude 119°48.70' W, observed gravity value 979674.65 mGal), also on the UNR campus. The isostatic gravity map (figure 3) includes additional data sets from the following sources: 202 stations from a Geological Survey digital data set (Ponce, 1997), and 126 stations from Thomas C. Carpenter (written commun., 1998).

  14. Results from an absolute gravity survey in the United States

    NASA Technical Reports Server (NTRS)

    Zumberge, M. A.; Faller, J. E.; Gschwind, J.

    1983-01-01

    Using the recently completed JTLA absolute gravity meter, we made a survey of twelve sites in the United States. Over a period of eight weeks, the instrument was driven a total distance of nearly 20,000 km to sites in California, New Mexico, Colorado, Wyoming, Maryland and Massachusetts. The time spent in carrying out a measurement at a single location was typically one day. We report the results of the measurements in this survey along with earlier measurements made with the instrument, discuss the measurement accuracy and compare our results with other measurements. Previously announced in STAR as N83-20480

  15. Results from an absolute gravity survey in the United States

    NASA Astrophysics Data System (ADS)

    Zumberge, M. A.; Faller, J. E.; Gschwind, J.

    1983-09-01

    Using the recently completed JTLA absolute gravity meter, we made a survey of twelve sites in the United States. Over a period of eight weeks, the instrument was driven a total distance of nearly 20,000 km to sites in California, New Mexico, Colorado, Wyoming, Maryland and Massachusetts. The time spent in carrying out a measurement at a single location was typically one day. We report the results of the measurements in this survey along with earlier measurements made with the instrument, discuss the measurement accuracy and compare our results with other measurements. Previously announced in STAR as N83-20480

  16. Improving absolute gravity estimates by the L p -norm approximation of the ballistic trajectory

    NASA Astrophysics Data System (ADS)

    Nagornyi, V. D.; Svitlov, S.; Araya, A.

    2016-04-01

    Iteratively re-weighted least squares (IRLS) were used to simulate the L p -norm approximation of the ballistic trajectory in absolute gravimeters. Two iterations of the IRLS delivered sufficient accuracy of the approximation without a significant bias. The simulations were performed on different samplings and perturbations of the trajectory. For the platykurtic distributions of the perturbations, the L p -approximation with 3  <  p  <  4 was found to yield several times more precise gravity estimates compared to the standard least-squares. The simulation results were confirmed by processing real gravity observations performed at the excessive noise conditions.

  17. Combining GOCE and in-situ gravity data for precise gravity field determination and geophysical applications around the Japanese Antarctic station, Syowa, in Antarctica

    NASA Astrophysics Data System (ADS)

    Fukuda, Y.; Nogi, Y.; Matsuzaki, K.

    2012-12-01

    Syowa is the Japanese Antarctic wintering station in Lützow-Holm Bay, East Antarctica. The area around the station is considered to be a key for investigating the formation of Gondwana, because reconstruction models suggest a junction of the continents locates in the area. It is also important from a glaciological point of view, because there locates the Shirase Glacier, one of the major glaciers in Antarctica, near the station. Therefore the Japanese Antarctic Research Expedition (JARE) has been conducting in-situ gravity measurements in the area for a long period. The data sets accumulated are land gravity data since 1967, surface ship data since 1985, and airborne gravity data in 2006. However these in-situ gravity data usually suffered from the effects of instrumental drifts and lack of reference points, their accuracies are decreasing toward the longer wavelength more than several tens km. In particular in Antarctica where very few gravity reference points are available, the long wavelength accuracy and/or consistency among the data sets are quite limited. GOCE (Gravity field and steady-state Ocean Circulation Explorer) satellite launched in March 2009 by ESA (European Space Agency) aims at improving static gravity fields, in particular at short wavelengths. In addition to its low-altitude orbit (250km), the sensitive gravity gradiometer installed is expected to reveal 1 mgal gravity anomalies at the spatial resolution of 100km (half wavelength). Actually recently released GOCE EGMs (Earth Gravity Models) have improved the accuracy of the static gravity filed tremendously. These EGMs are expected to serve as the long wavelength references for the in-situ gravity data. Thus, firstly, we aims at determining an improved gravity fields around Syowa by combining the JARE gravity data and the recent EGMs. And then, using the gravity anomalies, we determine the subsurface density structures. We also evaluated the impacts of the EGMs for estimating the density

  18. Principal facts for gravity stations in Dixie; Fairview, and Stingaree valleys, Churchill and Pershing counties, Nevada

    USGS Publications Warehouse

    Schaefer, D.H.; Thomas, J.M.; Duffrin, B.G.

    1984-01-01

    During March through July 1979, gravity measurements were made at 300 stations in Dixie Valley, Nevada. In December 1981, 45 additional stations were added--7 in Dixie Valley, 23 in Fairview Valley, and 15 in Stingaree Valley. Most altitudes were determined by using altimeters or topographic maps. The gravity observations were made with a Worden temperature-controlled gravimeter with an initial scale factor of 0.0965 milliGal/scale division. Principal facts for each of the 345 stations are tabulated; they consist of latitude, longitude, altitude, observed gravity, free-air anomaly, terrain correction, and Bouguer anomaly values at a bedrock density of 2.67 grams/cu cm. (Lantz-PTT)

  19. Observations with FG5 and A10 absolute gravimeters on Ross Island and in Terra Nova Bay in November-December 2011

    NASA Astrophysics Data System (ADS)

    Rogister, Yves; Hothem, Larry; Nielsen, J. Emil; Bernard, Jean-Daniel; Hinderer, Jacques; Forsberg, René; Wilson, Terry; Capra, Alessandro; Zanutta, Antonio; Winefield, Rachelle; Collett, Dave

    2013-04-01

    A campaign of absolute gravity (AG) measurements was conducted with both FG5 and A10 meters on Ross Island and in Terra Nova Bay in November and December 2011. It resulted from a collaboration between Danish, French, Italian, New Zealand and US agencies and institutes, under the POLENET program. For the second time in 2 years, AG was measured at McMurdo Station and Scott Base. For the fifth time in 21 years, it was measured at Mario Zucchelli Station. Moreover, AG field observations were initiated at various GPS stations of the A-NET network. We will report on the very last campaign, show the gravity trends at McMurdo Station, Scott Base and Mario Zucchelli Station, and describe how they compare to estimates of the gravity variation derived from space measurements by the GRACE twin satellites.

  20. Changing the Bayesian prior: Absolute neutrino mass constraints in nonlocal gravity*

    NASA Astrophysics Data System (ADS)

    Dirian, Yves

    2017-10-01

    Prior change is discussed in observational constraints studies of nonlocally modified gravity, where a model characterized by a modification of the form ˜m2R □-2R to the Einstein-Hilbert action was compared against the base Λ CDM one in a Bayesian way. It was found that the competing modified gravity model is significantly disfavored (at 22 ∶1 in terms of betting-odds) against Λ CDM given CMB +SNIa +BAO data, because of a tension appearing in the H0- ΩM plane. We identify the underlying mechanism generating such a tension and show that it is mostly caused by the late-time, quite smooth, phantom nature of the effective dark energy described by the nonlocal model. We find that the tension is resolved by considering an extension of the initial baseline, consisting in allowing the absolute mass of three degenerated massive neutrino species ∑mν/3 to take values within a prior interval consistent with existing data. As a net effect, the absolute neutrino mass is inferred to be nonvanishing at 2 σ level, best-fitting at ∑mν≈0.21 eV , and the Bayesian tension disappears rendering the nonlocal gravity model statistically equivalent to Λ CDM , given recent CMB +SNIa +BAO data. We also discuss constraints from growth rate measurements f σ8, whose fit is found to be improved by a larger massive neutrino fraction as well. The ν -extended nonlocal model also prefers a higher value of H0 than Λ CDM , therefore in better agreement with local measurements. Our study provides one more example suggesting that the neutrino density fraction Ων is partially degenerated with the nature of the dark energy. This emphasizes the importance of cosmological and terrestrial neutrino research and, as a massive neutrino background impacts structure formation observables non-negligibly, proves to be especially relevant for future galaxy surveys.

  1. Gravity change from 2014 to 2015, Sierra Vista Subwatershed, Upper San Pedro Basin, Arizona

    USGS Publications Warehouse

    Kennedy, Jeffrey R.

    2016-09-13

    Relative-gravity data and absolute-gravity data were collected at 68 stations in the Sierra Vista Subwatershed, Upper San Pedro Basin, Arizona, in May–June 2015 for the purpose of estimating aquifer-storage change. Similar data from 2014 and a description of the survey network were published in U.S. Geological Survey Open-File Report 2015–1086. Data collection and network adjustment results are presented in this report, which is accompanied by a supporting Web Data Release (http://dx.doi.org/10.5066/F7SQ8XHX). Station positions are presented from a Global Positioning System campaign to determine station elevation.

  2. New gravity control in Poland - needs, the concept and the design

    NASA Astrophysics Data System (ADS)

    Krynski, Jan; Olszak, Tomasz; Barlik, Marcin; Dykowski, Przemyslaw

    2013-06-01

    The existing Polish gravity control (POGK) established in the last few years of 20th century according to the international standards is spanned on 12 absolute gravity stations surveyed with four different types of absolute gravimeters. Relative measurements performed by various groups on nearly 350 points of POGK with the use of LaCoste&Romberg (LCR) gravimeters were linked to those 12 stations. The construction of the network, in particular the limited number of non homogeneously distributed absolute gravity stations with gravity determined with different instruments in different epochs is responsible for systematic errors in g on POGK stations. The estimate of those errors with the use of gravity measurements performed in 2007-2008 is given and their possible sources are discussed. The development of absolute gravity measurement technologies, in particular instruments for precise field absolute gravity measurements, provides an opportunity to establish new type of gravity control consisting of stations surveyed with absolute gravimeters. New gravity control planned to be established in 2012-2014 will consist of 28 fundamental points (surveyed with the FG5 - gravimeter), and 169 base points (surveyed with the A10 gravimeter). It will fulfill recent requirements of geodesy and geodynamics and it will provide good link to the existing POGK. A number of stations of the new gravity control with precisely determined position and height will form the national combined geodetic network. Methodology and measurement schemes for both absolute gravimeters as well as the technology for vertical gravity gradient determinations in the new gravity control were developed and tested. The way to assure proper gravity reference level with relation to ICAG and ECAG campaigns as well as local absolute gravimeter comparisons are described highlighting the role of metrology in the project. Integral part of the project are proposals of re-computation of old gravity data and their

  3. Gravity measurements in southeastern Alaska reveal negative gravity rate of change caused by glacial isostatic adjustment

    NASA Astrophysics Data System (ADS)

    Sun, W.; Miura, S.; Sato, T.; Sugano, T.; Freymueller, J.; Kaufman, M.; Larsen, C. F.; Cross, R.; Inazu, D.

    2010-12-01

    For the past 300 years, southeastern Alaska has undergone rapid ice-melting and land uplift attributable to global warming. Corresponding crustal deformation (3 cm/yr) caused by the Little Ice Age retreat is detectable with modern geodetic techniques such as GPS and tidal gauge measurements. Geodetic deformation provides useful information for assessing ice-melting rates, global warming effects, and subcrustal viscosity. Nevertheless, integrated geodetic observations, including gravity measurements, are important. To detect crustal deformation caused by glacial isostatic adjustment and to elucidate the viscosity structure in southeastern Alaska, Japanese and U.S. researchers began a joint 3-year project in 2006 using GPS, Earth tide, and absolute gravity measurements. A new absolute gravity network was established, comprising five sites around Glacier Bay, near Juneau, Alaska. This paper reports the network's gravity measurements during 2006-2008. The bad ocean model in this area hindered ocean loading correction: Large tidal residuals remain in the observations. Accurate tidal correction necessitated on-site tidal observation. Results show high observation precision for all five stations: <1 μGal. The gravity rate of change was found to be -3.5 to -5.6 μGal/yr in the gravity network. Furthermore, gravity results obtained during the 3 years indicate a similar gravity change rate. These gravity data are anticipated for application in geophysical studies of southeastern Alaska. Using gravity and vertical displacement data, we constructed a quantity to remove viscoelastic effects. The observations are thus useful to constrain present-day ice thickness changes. A gravity bias of about -13.2 ± 0.1 mGal exists between the Potsdam and current FG5 gravity data.

  4. Earth's gravity field to the eighteenth degree and geocentric coordinates for 104 stations from satellite and terrestrial data

    NASA Technical Reports Server (NTRS)

    Gaposchkin, E. M.

    1973-01-01

    Geodetic parameters describing the earth's gravity field and the positions of satellite-tracking stations in a geocentric reference frame were computed. These parameters were estimated by means of a combination of five different types of data: routine and simultaneous satellite observations, observations of deep-space probes, measurements of terrestrial gravity, and surface-triangulation data. The combination gives better parameters than does any subset of data types. The dynamic solution used precision-reduced Baker-Nunn observations and laser range data of 25 satellites. Data from the 49-station National Oceanic and Atmospheric Administration BC-4 network, the 19-station Smithsonian Astrophysical Observatory Baker-Nunn network, and independent camera stations were employed in the geometrical solution. Data from the tracking of deep-space probes were converted to relative longitudes and distances to the earth's axis of rotation of the tracking stations. Surface-gravity data in the form of 550-km squares were derived from 19,328 1 deg X 1 deg mean gravity anomalies.

  5. Gravity increase before the 2015 Mw 7.8 Nepal earthquake

    NASA Astrophysics Data System (ADS)

    Chen, Shi; Liu, Mian; Xing, Lelin; Xu, Weimin; Wang, Wuxing; Zhu, Yiqing; Li, Hui

    2016-01-01

    The 25 April 2015 Nepal earthquake (Mw 7.8) ruptured a segment of the Himalayan front fault zone. Four absolute gravimetric stations in southern Tibet, surveyed from 2010/2011 to 2013 and corrected for secular variations, recorded up to 22.40 ± 1.11 μGal/yr of gravity increase during this period. The gravity increase is distinct from the long-wavelength secular trends of gravity decrease over the Tibetan Plateau and may be related to interseismic mass change around the locked plate interface under the Himalayan-Tibetan Plateau. We modeled the source region as a disk of 580 km in diameter, which is consistent with the notion that much of the southern Tibetan crust is involved in storing strain energy that drives the Himalayan earthquakes. If validated in other regions, high-precision ground measurements of absolute gravity may provide a useful method for monitoring mass changes in the source regions of potential large earthquakes.

  6. Artificial gravity studies and design considerations for Space Station centrifuges

    NASA Technical Reports Server (NTRS)

    Halstead, T. W.; Brown, A. H.; Fuller, C. A.; Oyama, J.

    1984-01-01

    The requirements to and capabilities of a Space Station biological facility centrifuge are discussed on the basis of an assessment of the objectives and subjects of future microgravity biological experiments. It is argued that the facility should be capable of both acute and extended chronic exposure of test subjects and biological materials to altered-g loading. In addition, the experimental approaches and equipment for microgravity studies on a Space Station are outlined. Finally, the engineering requirements of such a centrifuge are examined, with consideration of radial gravity gradients, size, and physical access to animals.

  7. Isostatic gravity map of the Nevada Test Site and vicinity, Nevada

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ponce, D.A.; Harris, R.N.; Oliver, H.W.

    1988-12-31

    The isostatic gravity map of the Nevada Test Site (NTS) and vicinity is based on about 16,000 gravity stations. Principal facts of the gravity data were listed by Harris and others (1989) and their report included descriptions of base stations, high-precision and absolute gravity stations, and data accuracy. Observed gravity values were referenced to the International Gravity Standardization Net 1971 gravity datum described by Morelli (1974) and reduced using the Geodetic Reference System 1967 formula for the normal gravity on the ellipsoid (International Union of Geodesy and Geophysics, 1971). Free-air, Bouguer, curvature, and terrain corrections for a standard reduction densitymore » of 2.67 g/cm{sup 3} were made to compute complete Bouguer anomalies. Terrain corrections were made to a radial distance of 166.7 km from each station using a digital elevation model and a computer procedure by Plouff (1977) and, in general, include manually estimated inner-zone terrain corrections. Finally, isostatic corrections were made using a procedure by Simpson and others (1983) based on an Airy-Heiskanen model with local compensation (Heiskanen and Moritz, 1967) with an upper-crustal density of 2.67 g/cm{sup 3}, a crustal thickness of 25 km, and a density contrast between the lower-crust and upper-mantle of 0.4 g/cm{sup 3}. Isostatic corrections help remove the effects of long-wavelength anomalies related to topography and their compensating masses and, thus, enhance short- to moderate-wavelength anomalies caused by near surface geologic features. 6 refs.« less

  8. Too Fast to Measure: Network Adjustment of Rapidly Changing Gravity Fields

    NASA Astrophysics Data System (ADS)

    Kennedy, J.; Ferre, T. P. A.

    2014-12-01

    Measurements of spatially-variable gravity at the field scale are difficult; measurements of the time-varying field even more so. Every previous gravity survey using relative gravimeters—still the workhorse of gravity studies, despite their nearly 80 year history—has assumed a static gravity field during the course of a survey, which may last days to weeks. With recently-improved instrumentation, however, measurements of fields changing on the order of tens of nm/sec2 per day are now possible. In particular, the A-10 portable absolute gravimeter provides not only absolute control, but also the change in that control during the course of a survey. Using digitally-recording spring-based relative gravimeters (namely, the ZLS Burris meter and the Scintrex CG-5), with their more efficient data collection and lower drift than previous generations, many more data are collected in a day. We demonstrate a method for incorporating in the least-squares network adjustment of relative gravity data a relation between the rate of change of gravity, dg, and distance from an infiltration source, x. This relation accounts for the fact that gravity at stations adjacent to the infiltration source changes more rapidly than stations further away; if all measurements collected over several days are to be included in a single network-adjustment, consideration of this change is required. Two methods are used to simulate the dg(x) relation: a simple model where dg is a linear function of x, and a coupled-hydrogeophysical method where a groundwater flow model predicts the nonlinear spatial variation of dg. Then, the change in gravity between different, independently adjusted surveys is used to parameterize the groundwater model. Data from two recent field examples, an artificial recharge facility near Tucson, Arizona, USA, and from the 2014 Lower Colorado River pulse flow experiment, clearly show the need to account for gravity change during a survey; maximum rates of change for the two

  9. Near-station terrain corrections for gravity data by a surface-integral technique

    USGS Publications Warehouse

    Gettings, M.E.

    1982-01-01

    A new method of computing gravity terrain corrections by use of a digitizer and digital computer can result in substantial savings in the time and manual labor required to perform such corrections by conventional manual ring-chart techniques. The method is typically applied to estimate terrain effects for topography near the station, for example within 3 km of the station, although it has been used successfully to a radius of 15 km to estimate corrections in areas where topographic mapping is poor. Points (about 20) that define topographic maxima, minima, and changes in the slope gradient are picked on the topographic map, within the desired radius of correction about the station. Particular attention must be paid to the area immediately surrounding the station to ensure a good topographic representation. The horizontal and vertical coordinates of these points are entered into the computer, usually by means of a digitizer. The computer then fits a multiquadric surface to the input points to form an analytic representation of the surface. By means of the divergence theorem, the gravity effect of an interior closed solid can be expressed as a surface integral, and the terrain correction is calculated by numerical evaluation of the integral over the surfaces of a cylinder, The vertical sides of which are at the correction radius about the station, the flat bottom surface at the topographic minimum, and the upper surface given by the multiquadric equation. The method has been tested with favorable results against models for which an exact result is available and against manually computed field-station locations in areas of rugged topography. By increasing the number of points defining the topographic surface, any desired degree of accuracy can be obtained. The method is more objective than manual ring-chart techniques because no average compartment elevations need be estimated ?

  10. Gravity effects obtained from global hydrology models in comparison with high precision gravimetric time series

    NASA Astrophysics Data System (ADS)

    Wziontek, Hartmut; Wilmes, Herbert; Güntner, Andreas; Creutzfeldt, Benjamin

    2010-05-01

    Water mass changes are a major source of variations in residual gravimetric time series obtained from the combination of observations with superconducting and absolute gravimeters. Changes in the local water storage are the main influence, but global variations contribute to the signal significantly. For three European gravity stations, Bad Homburg, Wettzell and Medicina, different global hydrology models are compared. The influence of topographic effects is discussed and due to the long-term stability of the combined gravity time series, inter-annual signals in model data and gravimetric observations are compared. Two sources of influence are discriminated, i.e., the effect of a local zone with an extent of a few kilometers around the gravimetric station and the global contribution beyond 50km. Considering their coarse resolution and uncertainties, local effects calculated from global hydrological models are compared with the in-situ gravity observations and, for the station Wettzell, with local hydrological monitoring data.

  11. Hydrologic Interpretations of Long-Term Gravity Records at Tucson, Arizona

    NASA Astrophysics Data System (ADS)

    Pool, D. R.; Kennedy, J.; MacQueen, P.; Niebauer, T. M.

    2016-12-01

    The USGS Arizona Water Science Center monitors groundwater storage using gravity methods at sites across the western United States. A site at the USGS office in Tucson serves as a test station that has been monitored since 1997 using several types of gravity meters. Prior to 2007, the site was observed twice each year by the National Geodetic Survey using an FG5 absolute gravity meter for the purpose of establishing control for local relative gravity surveys of aquifer storage change. Beginning in 2003 the site has also served as a reference to verify the accuracy of an A10 absolute gravity meter that is used for field surveys. The site is in an alluvial basin where gravity can vary with aquifer storage change caused by variable groundwater withdrawals, elevation change caused by aquifer compaction or expansion, and occasional recharge. In addition, continuous gravity records were collected for periods of several months using a super-conducting meter during 2010-2011 and using a spring-based gPhone meter during 2015-2016. The purpose of the continuous records was to provide more precise information about monthly and shorter period variations that could be related to variations in nearby groundwater withdrawals. The record of absolute gravity observations displays variations of as much as 35 microGal that correspond with local hydrologic variations documented from precipitation, streamflow, elevation, depths to water, and well pumping records. Depth to water in nearby wells display variations related to occasional local heavy precipitation events, runoff, recharge, and groundwater withdrawals. Increases in gravity that occur over periods of several months or longer correspond with occasional heavy precipitation and recharge. Periods of gravity decline occur during extended periods between recharge events and periods of increased local groundwater withdrawals. Analysis of the continuous records from both instruments indicate that groundwater drains slowly from

  12. Estimating aquifer properties using time-lapse, high precision gravity surveys and groundwater modeling

    NASA Astrophysics Data System (ADS)

    Keating, E.; Cogbill, A. H.; Ferguson, J. F.

    2003-12-01

    In the past, gravity methods have had limited application for monitoring aquifers, primarily due to the poor drift characteristics of relative gravimeters, which made long-term gravity studies of aquifers prohibitively expensive. Recent developments in portable, very accurate, absolute gravity instruments having essentially zero long-term drift have reawakened interest in using gravity methods for hydrologic monitoring. Such instruments have accuracies of 7 microGals or better and can acquire measurements at the rate of better than one station per hour. Theoretically, temporal changes in gravity can be used to infer storage characteristics and fluxes into and out of the aquifer. The sensitivity of the method to scaling effects, temporal lags between recharge/discharge and changes in storage, and to uncertainties in aquifer structure are poorly understood. In preparation for interpreting a basin-scale, time-lapse gravity data set, we have established a network of gravity stations within the Espanola Basin in northern New Mexico, a semi-arid region which is experiencing rapid population growth and groundwater resource use. We are using an existing basin-scale groundwater flow model to predict changes in mass, given our current level of understanding of inflows, outflows, and aquifer properties. Preliminary model results will be used to examine scaling issues related to the spatial density of the gravity station network and depths to the regional water table. By modeling the gravitational response to water movement in the aquifer, we study the sensitivity of gravity measurements to aquifer storage properties, given other known uncertainties in basin-scale fluxes. Results will be used to evaluate the adequacy of the existing network and to modify its design, if necessary.

  13. How absolute EIT reflects the dependence of unilateral lung aeration on hyper-gravity and weightlessness?

    PubMed

    Hahn, G; Just, A; Hellige, G; Dittmar, J; Quintel, M

    2013-09-01

    We studied the influence of three gravity levels (0, 1 and 1.8 g) on unilateral lung aeration in a left lateral position by the application of absolute electrical impedance tomography. The electrical resistivity of the lung tissue was considered to be a meaningful indicator for lung aeration since changes in resistivity have already been validated in other studies to be proportional to changes in lung volume. Twenty-two healthy volunteers were studied during parabolic flights with three phases of different gravity, each lasting ∼20-22 s. Spontaneous breathing at normal tidal volume VT and at increased VT was performed. During transition to hyper-gravity mean expiratory resistivities (±SD in Ωm) increased at normal VT in the upper (right) lung from 7.6 ± 1.5 to 8.0 ± 1.7 and decreased from 5.8 ± 1.2 to 5.7 ± 1.2 in the lower (left) lung. Inspiratory resistivity values are 8.3 ± 1.6 to 8.8 ± 1.8 (right) and 6.3 ± 1.3 to 6.0 ± 1.3 (left). At increased VT, the changes in resistivities at end-expiration were 7.7 ± 1.5 to 8.0 ± 1.7 (right) and 5.8 ± 1.2 to 5.7 ± 1.2 (left). Corresponding end-inspiratory values are 9.9 ± 1.9 to 10.0 ± 2.0 (right) and 8.6 ± 2.1 to 7.9 ± 2.0 (left). During weightlessness, the distortion in the lungs disappeared and both lungs showed a nearly identical aeration, which was between the levels displayed at normal gravity. The small increase in resistivity for the upper lung during transition to hyper-gravity from 1 to 1.8 g at increased VT suggests that the degressive part of the pressure-volume curve has already been reached at end-inspiration. The results for a left lateral position are in agreement with West's lung model which has been introduced for cranio-caudal gravity dependence in the lungs.

  14. a Portable Apparatus for Absolute Measurements of the Earth's Gravity.

    NASA Astrophysics Data System (ADS)

    Zumberge, Mark Andrew

    We have developed a new, portable apparatus for making absolute measurements of the acceleration due to the earth's gravity. We use the method of interferometrically determining the acceleration of a freely falling corner -cube prism. The falling object is surrounded by a chamber which is driven vertically inside a fixed vacuum chamber. This falling chamber is servoed to track the falling corner -cube to shield it from drag due to background gas. In addition, the drag-free falling chamber removes the need for a magnetic release, shields the falling object from electrostatic forces, and provides a means of both gently arresting the falling object and quickly returning it to its start position, to allow rapid acquisition of data. A synthesized long period isolation device reduces the noise due to seismic oscillations. A new type of Zeeman laser is used as the light source in the interferometer, and is compared with the wavelength of an iodine stabilized laser. The times of occurrence of 45 interference fringes are measured to within 0.2 nsec over a 20 cm drop and are fit to a quadratic by an on-line minicomputer. 150 drops can be made in ten minutes resulting in a value of g having a precision of 3 to 6 parts in 10('9). Systematic errors have been determined to be less than 5 parts in 10('9) through extensive tests. Three months of gravity data have been obtained with a reproducibility ranging from 5 to 10 parts in 10('9). The apparatus has been designed to be easily portable. Field measurements are planned for the immediate future. An accuracy of 6 parts in 10('9) corresponds to a height sensitivity of 2 cm. Vertical motions in the earth's crust and tectonic density changes that may precede earthquakes are to be investigated using this apparatus.

  15. Coupled Gravity and Elevation Measurements of Ice Sheet Mass Change

    NASA Technical Reports Server (NTRS)

    Jezek, K. C.

    2005-01-01

    We measured surface gravity and position at ten locations about two glaciological measurement networks located on the South-central Greenland Ice during June 2004. Six of the individual sites of the first network were occupied the previous year. At the repeat sites we were able to measure annual accumulation rate and surface displacement by referencing measurements to aluminum poles left in the firn the previous year. We occupied 4 additional sites at a second measurement network for the first time since initial observations were last made at the network in 1981. At each individual site, we operated a GPS unit for 90 minutes - the unit was operated simultaneously with a base station unit in Sondrestrom Fjord so as to enable differential, post-processing of the data. We installed an aluminum, accumulation-rate-pole at each site. The base section of the pole also served as the mount for the GPS antenna. A new, Scintrex gravimeter was used at each site and relative gravity measurements were tied to the network of absolute gravity stations in Sondrestrom. We measured snow physical properties in two shallow pits. This report summarizes our observations and data analysis.

  16. Artificial gravity in space and in medical research

    NASA Technical Reports Server (NTRS)

    Cardus, D.

    1994-01-01

    The history of manned space flight has repeatedly documented the fact that prolonged sojourn in space causes physiological deconditioning. Physiological deterioration has raised a legitimate concern about man's ability to adequately perform in the course of long missions and even the possibility of leading to circumstances threatening survival. One of the possible countermeasures of physiological deconditioning, theoretically more complete than others presently used since it affects all bodily systems, is artificial gravity. Space stations and spacecrafts can be equipped with artificial gravity, but is artificial gravity necessary? The term "necessary" must be qualified because a meaningful answer to the question depends entirely on further defining the purpose of space travel. If man intends to stay only temporarily in space, then he must keep himself in good physical condition so as to be able to return to earth or to land on any other planetary surface without undue exposure to major physiological problems resulting from transition through variable gravitational fields. Such a situation makes artificial gravity highly desirable, although perhaps not absolutely necessary in the case of relative short exposure to microgravity, but certainly necessary in interplanetary flight and planetary landings. If the intent is to remain indefinitely in space, to colonize space, then artificial gravity may not be necessary, but in this case the consequences of long term effects of adaptation to weightlessness will have to be weighed against the biological evolutionary outcomes that are to be expected. At the moment, plans for establishing permanent colonies in space seem still remote. More likely, the initial phase of exploration of the uncharted solar system will take place through successive, scope limited, research ventures ending with return to earth. This will require man to be ready to operate in gravitational fields of variable intensity. Equipping spacecrafts or space

  17. Artificial gravity in space and in medical research.

    PubMed

    Cardús, D

    1994-05-01

    The history of manned space flight has repeatedly documented the fact that prolonged sojourn in space causes physiological deconditioning. Physiological deterioration has raised a legitimate concern about man's ability to adequately perform in the course of long missions and even the possibility of leading to circumstances threatening survival. One of the possible countermeasures of physiological deconditioning, theoretically more complete than others presently used since it affects all bodily systems, is artificial gravity. Space stations and spacecrafts can be equipped with artificial gravity, but is artificial gravity necessary? The term "necessary" must be qualified because a meaningful answer to the question depends entirely on further defining the purpose of space travel. If man intends to stay only temporarily in space, then he must keep himself in good physical condition so as to be able to return to earth or to land on any other planetary surface without undue exposure to major physiological problems resulting from transition through variable gravitational fields. Such a situation makes artificial gravity highly desirable, although perhaps not absolutely necessary in the case of relative short exposure to microgravity, but certainly necessary in interplanetary flight and planetary landings. If the intent is to remain indefinitely in space, to colonize space, then artificial gravity may not be necessary, but in this case the consequences of long term effects of adaptation to weightlessness will have to be weighed against the biological evolutionary outcomes that are to be expected. At the moment, plans for establishing permanent colonies in space seem still remote. More likely, the initial phase of exploration of the uncharted solar system will take place through successive, scope limited, research ventures ending with return to earth. This will require man to be ready to operate in gravitational fields of variable intensity. Equipping spacecrafts or space

  18. Separating Mass and Height Contributions in Gravity Variations at Medicina, Italy

    NASA Astrophysics Data System (ADS)

    Zerbini, S.; Bruni, S.; Errico, M.; Santi, E.; Wziontek, H.

    2016-12-01

    During 1996, at the Medicina station, a GPS and a superconducting gravimeter (SG) were installed in the framework of an experiment focused on the comparison between height and gravity variations. Absolute gravity observations are also performed twice a year and environmental parameters, among others water table levels, are recorded continuously. The station is also equipped with a second GPS system, the two antennas are very close to each other, and both are located in close proximity to the VLBI dish. Two decades of continuous height and gravity observations are now available which allow investigating both long and short period signals and the relevant correlations between the two measured quantities. Long period signatures are observed, a principal component is due to subsidence which is well known to occur in the area; however, also non-linear long-period behaviors are observed. Seasonal effects are also clearly recognizable in the time series and are mainly associated with the water table seasonal behavior. The station is characterized by clayey soil which is subject to consolidation effects when the water table lowers during the summer period. This effect is particularly recognizable in the SG data since the instrument is installed on a shallow foundation pillar which may suffer for height decreases in the order of 2,5-3 cm for water table lowering of 2 m.

  19. Tethered gravity laboratories study

    NASA Technical Reports Server (NTRS)

    Lucchetti, F.

    1990-01-01

    The scope of the study is to investigate ways of controlling the microgravity environment of the International Space Station by means of a tethered system. Four main study tasks were performed. First, researchers analyzed the utilization of the tether systems to improve the lowest possible steady gravity level on the Space Station and the tether capability to actively control the center of gravity position in order to compensate for activities that would upset the mass distribution of the Station. The purpose of the second task was to evaluate the whole of the experiments performable in a variable gravity environment and the related beneficial residual accelerations, both for pure and applied research in the fields of fluid, materials, and life science, so as to assess the relevance of a variable g-level laboratory. The third task involves the Tethered Variable Gravity Laboratory. The use of the facility that would crawl along a deployed tether and expose experiments to varying intensities of reduced gravity is discussed. Last, a study performed on the Attitude Tether Stabilizer concept is discussed. The stabilization effect of ballast masses tethered to the Space Station was investigated as a means of assisting the attitude control system of the Station.

  20. Scientific uses and technical implementation of a variable gravity centrifuge on Space Station Freedom

    NASA Technical Reports Server (NTRS)

    Johnson, C. C.; Hargens, A. R.

    1990-01-01

    The potential need and science requirements for a centrifuge to be designed and flown on Space Station Freedom are discussed, with a focus on a design concept for a centrifuge developed at NASA Ames. Applications identified for the centrifuge include fundamental studies in which gravity is a variable under experimental control, the need to provide a 1-g control, attempts to discover the threshold value of gravitation force for psychological response, and an effort to determine the effects of intermittent hypergravity. Science requirements specify the largest possible diameter at approximately 2.5 m, gravity levels ranging from 0.01 to 2 g, a nominal ramp-up rate of 0.01 g/sec, and life support for plants and animals. Ground-based studies using rats and squirrel monkeys on small-diameter centrifuges have demonstrated that animals can adapt to centrifugation at gravity gradients higher than those normally used in ground-based hypergravity studies.

  1. A time-lapse gravity survey of the Coso geothermal field, China Lake Naval Air Weapons Station, California

    USGS Publications Warehouse

    Phelps, Geoffrey; Cronkite-Ratcliff, Collin; Blake, Kelly

    2018-04-19

    We have conducted a gravity survey of the Coso geothermal field to continue the time-lapse gravity study of the area initiated in 1991. In this report, we outline a method of processing the gravity data that minimizes the random errors and instrument bias introduced into the data by the Scintrex CG-5 relative gravimeters that were used. After processing, the standard deviation of the data was estimated to be ±13 microGals. These data reveal that the negative gravity anomaly over the Coso geothermal field, centered on gravity station CER1, is continuing to increase in magnitude over time. Preliminary modeling indicates that water-table drawdown at the location of CER1 is between 65 and 326 meters over the last two decades. We note, however, that several assumptions on which the model results depend, such as constant elevation and free-water level over the study period, still require verification.

  2. Estimated SLR station position and network frame sensitivity to time-varying gravity

    NASA Astrophysics Data System (ADS)

    Zelensky, Nikita P.; Lemoine, Frank G.; Chinn, Douglas S.; Melachroinos, Stavros; Beckley, Brian D.; Beall, Jennifer Wiser; Bordyugov, Oleg

    2014-06-01

    This paper evaluates the sensitivity of ITRF2008-based satellite laser ranging (SLR) station positions estimated weekly using LAGEOS-1/2 data from 1993 to 2012 to non-tidal time-varying gravity (TVG). Two primary methods for modeling TVG from degree-2 are employed. The operational approach applies an annual GRACE-derived field, and IERS recommended linear rates for five coefficients. The experimental approach uses low-order/degree coefficients estimated weekly from SLR and DORIS processing of up to 11 satellites (tvg4x4). This study shows that the LAGEOS-1/2 orbits and the weekly station solutions are sensitive to more detailed modeling of TVG than prescribed in the current IERS standards. Over 1993-2012 tvg4x4 improves SLR residuals by 18 % and shows 10 % RMS improvement in station stability. Tests suggest that the improved stability of the tvg4x4 POD solution frame may help clarify geophysical signals present in the estimated station position time series. The signals include linear and seasonal station motion, and motion of the TRF origin, particularly in Z. The effect on both POD and the station solutions becomes increasingly evident starting in 2006. Over 2008-2012, the tvg4x4 series improves SLR residuals by 29 %. Use of the GRGS RL02 series shows similar improvement in POD. Using tvg4x4, secular changes in the TRF origin Z component double over the last decade and although not conclusive, it is consistent with increased geocenter rate expected due to continental ice melt. The test results indicate that accurate modeling of TVG is necessary for improvement of station position estimation using SLR data.

  3. Seasonal and height variation of gravity wave activities observed by a meteor radar at King Sejong Station (62°S, 57°W), Antarctica

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Lee, C.; Kim, J.; Choi, J.; Jee, G.

    2010-12-01

    We have analyzed wind data from individual meteor echoes detected by a meteor radar at King Sejong Station, Antarctica to measure gravity wave activity in the mesopause region. Wind data in the meteor altitudes has been obtained routinely by the meteor radar since its installation in March 2007. The mean variances in the wind data that were filtered for large scale motions (mean winds and tides) can be regarded as the gravity wave activity. Monthly mean gravity wave activities show strong seasonal and height dependences in the altitude range of 80 to 100 km. The gravity wave activities except summer monotonically increase with altitude, which is expected since decreasing atmospheric densities cause wave amplitudes to increase. During summer (Dec. - Feb.) the height profiles of gravity wave activities show a minimum near 90 - 95 km, which may be due to different zonal wind and strong wind shear near 80 - 95 km. Our gravity wave activities are generally stronger than those of the Rothera station, implying sensitive dependency on location. The difference may be related to gravity wave sources in the lower atmosphere near Antarctic vortex.

  4. Field estimates of gravity terrain corrections and Y2K-compatible method to convert from gravity readings with multiple base stations to tide- and long-term drift-corrected observations

    USGS Publications Warehouse

    Plouff, Donald

    2000-01-01

    Gravity observations are directly made or are obtained from other sources by the U.S. Geological Survey in order to prepare maps of the anomalous gravity field and consequently to interpret the subsurface distribution of rock densities and associated lithologic or geologic units. Observations are made in the field with gravity meters at new locations and at reoccupations of previously established gravity "stations." This report illustrates an interactively-prompted series of steps needed to convert gravity "readings" to values that are tied to established gravity datums and includes computer programs to implement those steps. Inasmuch as individual gravity readings have small variations, gravity-meter (instrument) drift may not be smoothly variable, and acommodations may be needed for ties to previously established stations, the reduction process is iterative. Decision-making by the program user is prompted by lists of best values and graphical displays. Notes about irregularities of topography, which affect the value of observed gravity but are not shown in sufficient detail on topographic maps, must be recorded in the field. This report illustrates ways to record field notes (distances, heights, and slope angles) and includes computer programs to convert field notes to gravity terrain corrections. This report includes approaches that may serve as models for other applications, for example: portrayal of system flow; style of quality control to document and validate computer applications; lack of dependence on proprietary software except source code compilation; method of file-searching with a dwindling list; interactive prompting; computer code to write directly in the PostScript (Adobe Systems Incorporated) printer language; and high-lighting the four-digit year on the first line of time-dependent data sets for assured Y2K compatibility. Computer source codes provided are written in the Fortran scientific language. In order for the programs to operate, they first

  5. GARS O'Higgins as a core station for geodesy in Antarctica

    NASA Astrophysics Data System (ADS)

    Klügel, Thomas; Diedrich, Erhard; Falk, Reinhard; Hessels, Uwe; Höppner, Kathrin; Kühmstedt, Elke; Metzig, Robert; Plötz, Christian; Reinhold, Andreas; Schüler, Torben; Wojdziak, Reiner

    2014-05-01

    The German Antarctic Receiving Station GARS O'Higgins at the northern tip of the Antarctic Peninsula is a dual purpose facility for Earth observation since more than 20 years. It serves as a satellite ground station for payload data downlink and telecommanding of remote sensing satellites as well as a geodetic observatory for global reference frames and global change. Both applications use the same 9m diameter radio telescope. For space geodesy and astrometry the radio telescope significantly improves the coverage on the southern hemisphere and plays an essential role within the global Very Long Baseline Interferometry (VLBI) network. In particular the determination of the Earth Orientation Parameters (EOP) and the sky coverage of the International Celectial Reference Frame (ICRF) benefit from the location at high southern latitude. Further geodetic instrumentation includes different permanent GNSS receivers (since 1995), two SAR corner reflectors (since 2013) and in the past a PRARE system (1996 - 2004). In addition absolute gravity measurements were performed in 1997 and 2011. All geodetic reference points are tied together by a local survey network. The various geodetic instrumentation and the long time series at O'Higgins allow a reliable determination of crustal motions. VLBI station velocities, continuous GNSS time series and absolute gravity measurements consistently document an uplift rate of about 5 mm/a. A pressure gauge and a radar tide gauge being refererenced to space by a GNSS antenna on top allow the measurement of sea level changes independently from crustal motions, and the determination of the ellipsoidal height of the sea surface, which is, the geoid height plus the mean dynamic topography. The outstanding location on the Antarctic continent makes GARS O'Higgins also in future attractive for polar orbiting satellite missions and an essential station for the global VLBI network. Future plans envisage a development towards an observatory for

  6. Absolute marine gravimetry with matter-wave interferometry.

    PubMed

    Bidel, Y; Zahzam, N; Blanchard, C; Bonnin, A; Cadoret, M; Bresson, A; Rouxel, D; Lequentrec-Lalancette, M F

    2018-02-12

    Measuring gravity from an aircraft or a ship is essential in geodesy, geophysics, mineral and hydrocarbon exploration, and navigation. Today, only relative sensors are available for onboard gravimetry. This is a major drawback because of the calibration and drift estimation procedures which lead to important operational constraints. Atom interferometry is a promising technology to obtain onboard absolute gravimeter. But, despite high performances obtained in static condition, no precise measurements were reported in dynamic. Here, we present absolute gravity measurements from a ship with a sensor based on atom interferometry. Despite rough sea conditions, we obtained precision below 10 -5  m s -2 . The atom gravimeter was also compared with a commercial spring gravimeter and showed better performances. This demonstration opens the way to the next generation of inertial sensors (accelerometer, gyroscope) based on atom interferometry which should provide high-precision absolute measurements from a moving platform.

  7. Principal facts for gravity stations in the Elko, Steptoe Valley, Coyote Spring Valley, and Sheep Range areas, eastern and southern Nevada

    USGS Publications Warehouse

    Berger, D.L.; Schaefer, D.H.; Frick, E.A.

    1990-01-01

    Principal facts for 537 gravity stations in the carbonate-rock province of eastern and southern Nevada are tabulated and presented. The gravity data were collected in support of groundwater studies in several valleys. The study areas include the Elko area, northern Steptoe Valley, Coyote Spring Valley, and the western Sheep Range area. The data for each site include values for latitude, longitude, altitude, observed gravity, free- air anomaly, terrain correction, and Bouguer anomaly (calculated at a bedrock density of 2.67 g/cu cm. (USGS)

  8. Gravity increase at the south pole

    USGS Publications Warehouse

    Behrendt, John C.

    1967-01-01

    Abstract. Measurements made between December 1957 and January 1966 of the gravity difference between the McMurdo Sound pendulum station, which is on bedrock, and the South Pole station, which is on the Antarctic ice sheet, show a gravity increase at the South Pole of 0.11 milligals per year. The most likely hypothesis for the increase is that it was caused by ice flowing downslope across a gravity gradient and by the sinking of the South Pole station as a result of accumulation of ice. An alternate hypothesis that the gravity increase was caused by a decrease in ice thickness, of about 40 centimeters per year, is theoretically possible but is not supported by direct evidence.

  9. An evaluation of the accuracy of geomagnetic data obtained from an unattended, automated, quasi-absolute station

    USGS Publications Warehouse

    Herzog, D.C.

    1990-01-01

    A comparison is made of geomagnetic calibration data obtained from a high-sensitivity proton magnetometer enclosed within an orthogonal bias coil system, with data obtained from standard procedures at a mid-latitude U.S. Geological Survey magnetic observatory using a quartz horizontal magnetometer, a Ruska magnetometer, and a total field magnetometer. The orthogonal coil arrangement is used with the proton magnetometer to provide Deflected-Inclination-Deflected-Declination (DIDD) data from which quasi-absolute values of declination, horizontal intensity, and vertical intensity can be derived. Vector magnetometers provide the ordinate values to yield baseline calibrations for both the DIDD and standard observatory processes. Results obtained from a prototype system over a period of several months indicate that the DIDD unit can furnish adequate absolute field values for maintaining observatory calibration data, thus providing baseline control for unattended, remote stations. ?? 1990.

  10. Principal facts for gravity stations and physical property measurements in the Lake Mead 30' by 60' quadrangle, Nevada and Arizona

    USGS Publications Warehouse

    Langenheim, V.E.; Davidson, J.G.; Anderson, M.L.; Blank, H.R.

    1999-01-01

    The U.S. Geological Survey (USGS) collected 811 gravity stations on the Lake Mead 30' by 60' quadrangle from October, 1997 to September, 1999. These data were collected in support of geologic mapping of the Lake Mead quadrangle. In addition to these new data, gravity stations were compiled from a number of sources. These stations were reprocessed according to the reduction method described below and used for the new data. Density and magnetic susceptibility measurements were also performed on more than 250 rock samples. The Lake Mead quadrangle ranges from 360 to 360 30' north latitude and from 114° to 115° west longitude. It spans most of Lake Mead (see index map, below), the largest manmade lake in the United States, and includes most of the Lake Mead National Recreation Area. Its geology is very complex; Mesozoic thrust faults are exposed in the Muddy Mountains, Precambrian crystalline basement rocks are exhumed in tilted fault blocks near Gold Butte, extensive Tertiary volcanism is evident in the Black Mountains, and strike-slip faults of the right-lateral Las Vegas Valley shear zone and the left-lateral Lake Mead fault system meet near the Gale Hills. These gravity data and physical property measurements will aid in the 3-dimensional characterization of structure and stratigraphy in the quadrangle as part of the Las Vegas Urban Corridor mapping project.

  11. Adaptive topographic mass correction for satellite gravity and gravity gradient data

    NASA Astrophysics Data System (ADS)

    Holzrichter, Nils; Szwillus, Wolfgang; Götze, Hans-Jürgen

    2014-05-01

    Subsurface modelling with gravity data includes a reliable topographic mass correction. Since decades, this mandatory step is a standard procedure. However, originally methods were developed for local terrestrial surveys. Therefore, these methods often include defaults like a limited correction area of 167 km around an observation point, resampling topography depending on the distance to the station or disregard the curvature of the earth. New satellite gravity data (e.g. GOCE) can be used for large scale lithospheric modelling with gravity data. The investigation areas can include thousands of kilometres. In addition, measurements are located in the flight height of the satellite (e.g. ~250 km for GOCE). The standard definition of the correction area and the specific grid spacing around an observation point was not developed for stations located in these heights and areas of these dimensions. This asks for a revaluation of the defaults used for topographic correction. We developed an algorithm which resamples the topography based on an adaptive approach. Instead of resampling topography depending on the distance to the station, the grids will be resampled depending on its influence at the station. Therefore, the only value the user has to define is the desired accuracy of the topographic correction. It is not necessary to define the grid spacing and a limited correction area. Furthermore, the algorithm calculates the topographic mass response with a spherical shaped polyhedral body. We show examples for local and global gravity datasets and compare the results of the topographic mass correction to existing approaches. We provide suggestions how satellite gravity and gradient data should be corrected.

  12. Time-dependent gravity in southern California, May 1974 - Apr 1979

    NASA Technical Reports Server (NTRS)

    Whitcomb, J. H.; Franzen, W. O.; Given, J. W.; Pechman, J. C.; Ruff, L. J.

    1979-01-01

    Gravity measurements were coordinated with the long baseline three dimensional geodetic measurements of the Astronomical Radio Interferometric Earth Surveying project which used radio interferometry with extra-galactic radio sources. Gravity data from 28 of the stations had a single reading standard deviation of 11 microgal which gives a relative single determination between stations a standard deviation of 16 microgal. The largest gravity variation observed, 80 microgal, correlated with nearby waterwell variations and with smoothed rainfall. Smoothed rainfall data appeared to be a good indicator of the qualitative response of gravity to changing groundwater levels at other suprasediment stations, but frequent measurement of gravity at a station was essential until the quantitative calibration of the station's response to groundwater variations was accomplished.

  13. Analysis of low gravity tolerance of model experiments for space station: Preliminary results for directional solidification

    NASA Technical Reports Server (NTRS)

    Alexander, J. Iwan D.; Ouazzani, Jalil

    1988-01-01

    It has become clear from measurements of the acceleration environment in the Spacelab that the residual gravity levels on board a spacecraft in low Earth orbit can be significant and should be of concern to experimenters who wish to take advantage of the low gravity conditions on future Spacelab missions and on board the Space Station. The basic goals are to better understand the low gravity tolerance of three classes of materials science experiments: crystal growth from a melt, a vapor, and a solution. The results of the research will provide guidance toward the determination of the sensitivity of the low gravity environment, the design of the laboratory facilites, and the timelining of materials science experiments. To data, analyses of the effects of microgravity environment were, with a few exceptions, restricted to order of magnitude estimates. Preliminary results obtained from numerical models of the effects of residual steady and time dependent acceleration are reported on: heat, mass, and momentum transport during the growth of a dilute alloy by the Bridgman-Stockbarger technique, and the response of a simple fluid physics experiment involving buoyant convection in a square cavity.

  14. Local Hydrological effects in Membach, Belgium: influence on the long term gravity variation

    NASA Astrophysics Data System (ADS)

    van Camp, M.; Dassargues, A.; Vanneste, K.; Verbeeck, K.; Warnant, R.

    2003-04-01

    Absolute (AG) and superconducting (SG) gravity measurements have been performed since 1996 at the underground Membach Station (Ardenne, eastern Belgium). Two effects can be distinguished: one seasonal-like and a long-term geophysical trend. The first effect is a 5 µGal seasonal-like term due most probably and mainly to hydrological variations. To determine the thickness of the porous unconsolidated layer covering the fissured bed-rock (low-porosity argillaceous sandstone with quartzitic beds) through which the tunnel was excavated, geophysical prospecting has been undertaken above the Membach station. This shows that the thickness of the weathered zone covering the bedrock can be highly variable between zero and 10 meters (possibly due to palaeo mudflows linked to periglacial conditions in the area). This leads to highly variable (in space) saturation capacity of the subsoil above the gallery. The extensive geological researches will allow us to correct the gravity variations induced by the variable mass of water stored in the shallow partially saturated soil. This work can be essential to correct local effects that can mask regional effects such as changes in continental water storage. Local effects, indeed, could prevent the combination of satellite data (e.g. GRACE) with ground-based gravity measurements. On the other hand, studying the local seasonal variations also contributes to investigate the influence of the water storage variations in small river basins on the time dependent gravity field. The second effect is the detection of a very low geophysical trend in gravity of -0.5+/-0.1 µGal/year. The SG drift, the hydrological effects, and the origin of the low trend are discussed. In particular, we show a good correlation between the gravity measurements and the continuous GPS measurements being made since 1997 at 3 km from the station. Possible crustal deformations could be linked to active faults in the Ardenne and/or bordering the Roer Valley Graben, or

  15. Numerical estimates of secular effects in the translational-rotational motion of an orbital station with 'Martian' gravity on board

    NASA Astrophysics Data System (ADS)

    Koenov, D. Z.

    Attention is given to an orbital station consisting of two identical cylindrical spacecraft with symmetrical wings (solar arrays); connected by a long tether, the two craft rotate about an axis that passes through their common center of mass. It is assumed that a Martian type of gravity has been created on board. Numerical estimates show that, in the course of a single mean solar day, the station performs more than 15.5 revolutions around the earth.

  16. Parallel Observations with Three Superconducting Gravity Sensors During 2014-2015 at Metsähovi Geodetic Research Station, Finland

    NASA Astrophysics Data System (ADS)

    Virtanen, Heikki; Raja-Halli, Arttu

    2017-11-01

    The new dual-sphere superconducting gravimeter (SG) OSG-073 was installed at Metsähovi Geodetic Fundamental Station in Southern Finland in February 2014. Its two gravity sensors (N6 and N7) are side by side, not one on top of the other as in other earlier dual-sensor installations. The old SG T020 has been recording continuously since 1994-2016. This instrument is situated in the same room at a distance of 3 m from the dual-sphere SG. T020 observed simultaneously for 1 year with N6 and for 15 months with N7. The gravity signals observed by N6 and N7 are very similar, except for the initial exponential drift. We have calculated the power spectral density to compare the noise level of these instruments with other low noise SGs. In this paper we present the observed differences in the gravity time series of T020 and OSG-073, induced by local hydrology. We have observed a clear 10-20 nms-2 difference in the seasonal gravity variations of OSG-073 and T020. We have found clear gravity differences due to transient effect of heavy precipitation. In addition, we compare the remote effect on gravity due to variations in the Baltic Sea level and total water storage in Finland to the observed gravity signal. We also present modeling results of gravity variations due to local hydrology.

  17. Acceleration levels on board the Space Station and a tethered elevator for micro and variable-gravity applications

    NASA Technical Reports Server (NTRS)

    Lorenzini, E. C.; Cosmo, M.; Vetrella, S.; Moccia, A.

    1988-01-01

    This paper investigates the dynamics and acceleration levels of a new tethered system for micro and variable-gravity applications. The system consists of two platforms tethered on opposite sides to the Space Station. A fourth platform, the elevator, is placed in between the Space Station and the upper platform. Variable-g levels on board the elevator are obtained by moving this facility along the upper tether, while micro-g experiments are carried out on board the Space Station. By controlling the length of the lower tether the position of the system CM can be maintained on board the Space Station despite variations of the station's distribution of mass. The paper illustrates the mathematical model, the environmental perturbations and the control techniques which have been adopted for the simulation and control of the system dynamics. Two sets of results from two different simulation runs are shown. The first set shows the system dynamics and the acceleration spectra on board the Space Station and the elevator during station-keeping. The second set of results demonstrates the capability of the elevator to attain a preselected g-level.

  18. Using continuous GPS and absolute gravity to separate vertical land movements and changes in sea-level at tide-gauges in the UK.

    PubMed

    Teferle, F N; Bingley, R M; Williams, S D P; Baker, T F; Dodson, A H

    2006-04-15

    Researchers investigating climate change have used historical tide-gauge measurements from all over the world to investigate the changes in sea-level that have occurred over the last century or so. However, such estimates are a combination of any true sea-level variations and any vertical movements of the land at the specific tide-gauge. For a tide- gauge record to be used to determine the climate related component of changes in sea-level, it is therefore necessary to correct for the vertical land movement component of the observed change in sea-level.In 1990, the Institute of Engineering Surveying and Space Geodesy and Proudman Oceanographic Laboratory started developing techniques based on the Global Positioning System (GPS) for measuring vertical land movements (VLM) at tide-gauges in the UK. This paper provides brief details of these early developments and shows how they led to the establishment of continuous GPS (CGPS) stations at a number of tide-gauges. The paper then goes on to discuss the use of absolute gravity (AG), as an independent technique for measuring VLM at tide-gauges. The most recent results, from CGPS time-series dating back to 1997 and AG time-series dating back to 1995/1996, are then used to demonstrate the complementarity of these two techniques and their potential for providing site-specific estimates of VLM at tide-gauges in the UK.

  19. Space Station

    NASA Image and Video Library

    1952-01-01

    This is a von Braun 1952 space station concept. In a 1952 series of articles written in Collier's, Dr. Wernher von Braun, then Technical Director of the Army Ordnance Guided Missiles Development Group at Redstone Arsenal, wrote of a large wheel-like space station in a 1,075-mile orbit. This station, made of flexible nylon, would be carried into space by a fully reusable three-stage launch vehicle. Once in space, the station's collapsible nylon body would be inflated much like an automobile tire. The 250-foot-wide wheel would rotate to provide artificial gravity, an important consideration at the time because little was known about the effects of prolonged zero-gravity on humans. Von Braun's wheel was slated for a number of important missions: a way station for space exploration, a meteorological observatory and a navigation aid. This concept was illustrated by artist Chesley Bonestell.

  20. Gravity data of Nevada

    USGS Publications Warehouse

    Ponce, David A.

    1997-01-01

    Gravity data for the entire state of Nevada and adjacent parts of California, Utah, and Arizona are available on this CD-ROM. About 80,000 gravity stations were compiled primarily from the National Geophysical Data Center and the U.S. Geological Survey. Gravity data was reduced to the Geodetic Reference System of 1967 and adjusted to the Gravity Standardization Net 1971 gravity datum. Data were processed to complete Bouguer and isostatic gravity anomalies by applying standard gravity corrections including terrain and isostatic corrections. Selected principal fact references and a list of sources for data from the National Geophysical Data Center are included.

  1. Gravity and Height Variations at Medicina, Italy

    NASA Astrophysics Data System (ADS)

    Bruni, Sara; Zerbini, Susanna; Errico, Maddalena; Santi, Efisio; Wziontek, Hartmut

    2017-04-01

    Since 1996, at the Medicina station, height and gravity variations are monitored continuously by means of GPS, VLBI and superconducting gravimeter (SG) data. Additionally, absolute gravity observations are performed twice a year and environmental parameters, among others water table levels, are regularly acquired. Levelling between the different monuments at the site area is also carried out repeatedly to constrain local ties in the vertical position. Two GPS systems are located very close to each other, and both are in close proximity to the VLBI antenna. Twenty years of data are now available, which allow investigating both long- and short-period height and gravity signals together with their relevant correlations. Natural land subsidence, which is well known to occur in the area, is a major component of the observed long-term behavior; however, non-linear long-period signatures are also present in the time series. On a shorter time scale, fingerprints of the water table seasonal oscillations can be recognized in the data. The Medicina site is characterized by clayey soil subjected to consolidation effects when the water table lowers during summer periods. The pillar on which the SG is installed is especially affected because of its shallow foundation, causing height decreases in the order of 2.5-3 cm for water table lowering of 2 m. This study presents a comparative analysis of the different data sets with the aim of separating mass and deformation contributions in the SG gravity record.

  2. Gravity and geoid model for South America

    NASA Astrophysics Data System (ADS)

    Blitzkow, Denizar; Oliveira Cancoro de Matos, Ana Cristina; do Nascimento Guimarães, Gabriel; Pacino, María Cristina; Andrés Lauría, Eduardo; Nunes, Marcelo; Castro Junior, Carlos Alberto Correia e.; Flores, Fredy; Orihuela Guevara, Nuris; Alvarez, Ruber; Napoleon Hernandez, José

    2016-04-01

    In the last 20 years, South America Gravity Studies (SAGS) project has undertaken an ongoing effort in establishing the fundamental gravity network (FGN); terrestrial, river and airborne relative gravity densifications; absolute gravity surveys and geoid (quasi-geoid) model computation for South America. The old FGN is being replaced progressively by new absolute measurements in different countries. In recent years, Argentina, Bolivia, Brazil, Ecuador, Paraguay and Venezuela organizations participated with relative gravity surveys. Taking advantage of the large amount of data available, GEOID2015 model was developed for 15°N and 57°S latitude and 30 ° W and 95°W longitude based on EIGEN-6C4 until degree and order 200 as a reference field. The ocean area was completed with mean free air gravity anomalies derived from DTU10 model. The short wavelength component was estimated using FFT. The global gravity field models EIGEN-6C4, DIR_R5 were used for comparison with the new model. The new geoid model has been evaluated against 1,319 GPS/BM, in which 592 are located in Brazil and the reminder in other countries. The preliminary RMS difference between GPS/BM and GEOID2015 throughout South America and in Brazil is 46 cm and 17 cm, respectively. New activities are carrying out with the support of the IGC (Geographic and Cartographic Institute) under the coordination of EPUSP/LTG and CENEGEO (Centro de Estudos de Geodesia). The new project aims to establish new gravity points with the A-10 absolute gravimeter in South America. Recent such surveys occurred in São Paulo state, Argentina and Venezuela.

  3. Gravity and Displacement Variations in the Areas of Strong Earthquakes in the East of Russia

    NASA Astrophysics Data System (ADS)

    Timofeev, V. Yu.; Kalish, E. N.; Stus', Yu. F.; Ardyukov, D. G.; Valitov, M. G.; Timofeev, A. V.; Nosov, D. A.; Sizikov, I. S.; Boiko, E. V.; Gornov, P. Yu.; Kulinich, R. G.; Kolpashchikova, T. N.; Proshkina, Z. N.; Nazarov, E. O.; Kolmogorov, V. G.

    2018-05-01

    The modern gravimetry methods are capable of measuring gravity with an accuracy of up to 10-10 of the normal value, which is commensurate with the accuracy of the up-to-date methods of displacement measurements by satellite geodesy. Significant changes, e.g., in the coseismic displacements of the Earth's surface are recorded in the zones of large earthquakes. These changes should manifest themselves in the variations of gravity. Absolute measurements have been conducted by various modifications of absolute ballistic gravimeters GABL since the mid-1970s at the Klyuchi point (Novosibirsk) in the south of the West Siberian plate. Monitoring observations have been taking place in the seismically active regions since the 1990s. In this paper we consider the results of the long-term measurements of the variations in gravity and recent crustal displacements for different types of earthquakes (the zones of shear, extension, and compression). In the seismically active areas in the east of Russia, the longest annual series of absolute measurements starting from 1992 was recorded in the southeastern segment of Baikal region. In this area, the Kultuk earthquake with magnitude 6.5 occurred on August 27, 2008, at a distance of 25 km from the observation point of the Talaya seismic station. The measurements in Gornyi (Mountainous) Altai have been conducted since 2000. A strikeslip earthquake with magnitude 7.5 took place in the southern segment of the region on September 27, 2003. The effects of the catastrophic M = 9.0 Tohoku, Japan, earthquake of March 11, 2011 were identified in Primor'e in the far zone of the event. The empirical data are consistent with the results of modeling based on the seismological data. The coseismic variations in gravity are caused by the combined effect of the changes in the elevation of the observation point and crustal deformation.

  4. Atom-chip based quantum gravimetry for the precise determination of absolute local gravity

    NASA Astrophysics Data System (ADS)

    Abend, S.

    2015-12-01

    We present a novel technique for the precise measurement of absolute local gravity based on cold atom interferometry. Atom interferometry utilizes the interference of matter waves interrogated by laser light to read out inertial forces. Today's generation of these devices typically operate with test mass samples, that consists of ensembles of laser cooled atoms. Their performance is limited by the velocity spread and finite-size of the test masses that impose systematic uncertainties at the level of a few μGal. Rather than laser cooled atoms we employ quantum degenerate ensembles, so called Bose-Einstein condensates, as ultra-sensitive probes for gravity. These sources offer unique properties in temperature as well as in ensemble size that will allow to overcome the current limitations with the next generation of sensors. Furthermore, atom-chip technologies offer the possibility to generate Bose-Einstein condensates in a fast and reliable way. We show a lab-based prototype that uses the atom-chip itself to retro-reflect the interrogation laser and thus serving as inertial reference inside the vacuum. With this setup it is possible to demonstrate all necessary steps to measure gravity, including the preparation of the source, spanning an interferometer as well as the detection of the output signal, within an area of 1 cm3 right below the atom-chip and to analyze relevant systematic effects. In the framework of the center of excellence geoQ a next generation device is under construction at the Institut für Quantenoptik, that will allow for in-field measurements. This device will feature a state-of-the-art atom-chip source with a high-flux of ultra-cold atoms at a repetition rate of 1-2 Hz. In cooperation with the Müller group at the Institut für Erdmessung the sensor will be characterized in the laboratory first, to be ultimately employed in campaigns to measure the Fennoscandian uplift at the level of 1 μGal. The presented work is part of the center of

  5. History of Artificial Gravity. Chapter 3

    NASA Technical Reports Server (NTRS)

    Clement, Gilles; Bukley, Angie; Paloski, William

    2006-01-01

    This chapter reviews the past and current projects on artificial gravity during space missions. The idea of a rotating wheel-like space station providing artificial gravity goes back in the writings of Tsiolkovsky, Noordung, and Wernher von Braun. Its most famous fictional representation is in the film 2001: A Space Odyssey, which also depicts spin-generated artificial gravity aboard a space station and a spaceship bound for Jupiter. The O Neill-type space colony provides another classic illustration of this technique. A more realistic approach to rotating the space station is to provide astronauts with a smaller centrifuge contained within a spacecraft. The astronauts would go into it for a workout, and get their gravity therapeutic dose for a certain period of time, daily or a few times a week. This simpler concept is current being tested during ground-based studies in several laboratories around the world.

  6. Accounting for time- and space-varying changes in the gravity field to improve the network adjustment of relative-gravity data

    USGS Publications Warehouse

    Kennedy, Jeffrey R.; Ferre, Ty P.A.

    2015-01-01

    The relative gravimeter is the primary terrestrial instrument for measuring spatially and temporally varying gravitational fields. The background noise of the instrument—that is, non-linear drift and random tares—typically requires some form of least-squares network adjustment to integrate data collected during a campaign that may take several days to weeks. Here, we present an approach to remove the change in the observed relative-gravity differences caused by hydrologic or other transient processes during a single campaign, so that the adjusted gravity values can be referenced to a single epoch. The conceptual approach is an example of coupled hydrogeophysical inversion, by which a hydrologic model is used to inform and constrain the geophysical forward model. The hydrologic model simulates the spatial variation of the rate of change of gravity as either a linear function of distance from an infiltration source, or using a 3-D numerical groundwater model. The linear function can be included in and solved for as part of the network adjustment. Alternatively, the groundwater model is used to predict the change of gravity at each station through time, from which the accumulated gravity change is calculated and removed from the data prior to the network adjustment. Data from a field experiment conducted at an artificial-recharge facility are used to verify our approach. Maximum gravity change due to hydrology (observed using a superconducting gravimeter) during the relative-gravity field campaigns was up to 2.6 μGal d−1, each campaign was between 4 and 6 d and one month elapsed between campaigns. The maximum absolute difference in the estimated gravity change between two campaigns, two months apart, using the standard network adjustment method and the new approach, was 5.5 μGal. The maximum gravity change between the same two campaigns was 148 μGal, and spatial variation in gravity change revealed zones of preferential infiltration and areas of relatively

  7. Gravity Waves in the Southern Hemisphere Extratropical Winter in the 7-km GEOS-5 Nature Run

    NASA Astrophysics Data System (ADS)

    Holt, L. A.; Alexander, M. J.; Coy, L.; Putman, W.; Molod, A.; Pawson, S.

    2016-12-01

    This study investigates winter Southern Hemisphere extratropical gravity waves and their sources in a 7-km horizontal resolution global climate simulation, the GEOS-5 Nature Run (NR). Gravity waves are evaluated by comparing brightness temperature anomalies to those from the Atmospheric Infrared Sounder (AIRS). Gravity wave amplitudes, wavelengths, and propagation directions are also computed in the NR and AIRS. The NR shows good agreement with AIRS in terms of spatial patterns of gravity wave activity and propagation directions, but the NR amplitudes are smaller by about a factor of 5 and the wavelengths are about a factor of 2 longer than in AIRS. In addition to evaluating gravity wave characteristics, gravity wave sources in the NR are also investigated by relating diagnostics of tropospheric sources of gravity waves, such as precipitation, frontogenesis, and potential vorticity anomalies to absolute gravity wave momentum fluxes in the lower stratosphere. Strong precipitation events are the most strongly correlated with absolute momentum flux, supporting previous studies highlighting the importance of moist processes in the generation of Southern Hemisphere extratropical gravity waves. Additionally, gravity wave absolute momentum fluxes over land are compared to those over ocean, and the contribution of orographic and nonorographic gravity waves to the total absolute momentum flux is examined.

  8. The spinning artificial gravity environment: A design project

    NASA Technical Reports Server (NTRS)

    Pignataro, Robert; Crymes, Jeff; Marzec, Tom; Seibert, Joe; Walker, Gary

    1987-01-01

    The SAGE, or Spinning Artificial Gravity Environment, design was carried out to develop an artificial gravity space station which could be used as a platform for the performance of medical research to determine the benefits of various, fractional gravity levels for astronauts normally subject to zero gravity. Desirable both for its medical research mission and a mission for the study of closed loop life-support and other factors in prolonged space flight, SAGE was designed as a low Earth orbiting, solar powered, manned space station.

  9. Gravity gradient preprocessing at the GOCE HPF

    NASA Astrophysics Data System (ADS)

    Bouman, J.; Rispens, S.; Gruber, T.; Schrama, E.; Visser, P.; Tscherning, C. C.; Veicherts, M.

    2009-04-01

    One of the products derived from the GOCE observations are the gravity gradients. These gravity gradients are provided in the Gradiometer Reference Frame (GRF) and are calibrated in-flight using satellite shaking and star sensor data. In order to use these gravity gradients for application in Earth sciences and gravity field analysis, additional pre-processing needs to be done, including corrections for temporal gravity field signals to isolate the static gravity field part, screening for outliers, calibration by comparison with existing external gravity field information and error assessment. The temporal gravity gradient corrections consist of tidal and non-tidal corrections. These are all generally below the gravity gradient error level, which is predicted to show a 1/f behaviour for low frequencies. In the outlier detection the 1/f error is compensated for by subtracting a local median from the data, while the data error is assessed using the median absolute deviation. The local median acts as a high-pass filter and it is robust as is the median absolute deviation. Three different methods have been implemented for the calibration of the gravity gradients. All three methods use a high-pass filter to compensate for the 1/f gravity gradient error. The baseline method uses state-of-the-art global gravity field models and the most accurate results are obtained if star sensor misalignments are estimated along with the calibration parameters. A second calibration method uses GOCE GPS data to estimate a low degree gravity field model as well as gravity gradient scale factors. Both methods allow to estimate gravity gradient scale factors down to the 10-3 level. The third calibration method uses high accurate terrestrial gravity data in selected regions to validate the gravity gradient scale factors, focussing on the measurement band. Gravity gradient scale factors may be estimated down to the 10-2 level with this method.

  10. Phototropism of Arabidopsis thaliana in microgravity and fractional gravity on the International Space Station.

    PubMed

    Kiss, John Z; Millar, Katherine D L; Edelmann, Richard E

    2012-08-01

    While there is a great deal of knowledge regarding plant growth and development in microgravity aboard orbiting spacecraft, there is little information available about these parameters in reduced or fractional gravity conditions (less than the nominal 1g on Earth). Thus, in these experiments using the European Modular Cultivation System on the International Space Station, we studied the interaction between phototropism and gravitropism in the WT and mutants of phytochrome A and B of Arabidopis thaliana. Fractional gravity and the 1 g control were provided by centrifuges in the spaceflight hardware, and unidirectional red and blue illumination followed a white light growth period in the time line of the space experiments. The existence of red-light-based positive phototropism in hypocotyls of seedlings that is mediated by phytochrome was confirmed in these microgravity experiments. Fractional gravity studies showed an attenuation of red-light-based phototropism in both roots and hypocotyls of seedlings occurring due to gravitational accelerations ranging from 0.l to 0.3 g. In contrast, blue-light negative phototropism in roots, which was enhanced in microgravity compared with the 1g control, showed a significant attenuation at 0.3 g. In addition, our studies suggest that the well-known red-light enhancement of blue-light-induced phototropism in hypocotyls is likely due to an indirect effect by the attenuation of gravitropism. However, red-light enhancement of root blue-light-based phototropism may occur via a more direct effect on the phototropism system itself, most likely through the phytochrome photoreceptors. To our knowledge, these experiments represent the first to examine the behavior of flowering plants in fractional or reduced gravity conditions.

  11. Laser interferometry method for absolute measurement of the acceleration of gravity

    NASA Technical Reports Server (NTRS)

    Hudson, O. K.

    1971-01-01

    Gravimeter permits more accurate and precise absolute measurement of g without reference to Potsdam values as absolute standards. Device is basically Michelson laser beam interferometer in which one arm is mass fitted with corner cube reflector.

  12. Principal facts for gravity stations in the Dry Valley area, west-central Nevada and east-central California

    USGS Publications Warehouse

    Sanger, Elizabeth A.; Ponce, David A.

    2003-01-01

    In June, 2002, the U.S. Geological Survey (USGS) established 143 new gravity stations and 12 new rock samples in the Dry Valley area, 30 miles north of Reno, Nevada, on the California - Nevada border (see fig. 1). This study reports on gravity, magnetic, and physical property data intended for use in modeling the geometry and depth of Dry Valley for groundwater analysis. It is part of a larger study that aims to characterize the hydrologic framework of several basins in Washoe County. Dry Valley is located south of the Fort Sage Mountains and south-east of Long Valley, on USGS 7.5’ quadrangles Constantia and Seven Lakes (fig. 2). The Cretaceous granitic rocks and Tertiary volcanic rocks that bound the sediment filled basin (fig. 3) may be especially important to future modeling because of their impact on groundwater flow. The granitic and volcanic rocks of Dry Valley exhibit densities and magnetic susceptibilities higher than the overlaying sediments, and create a distinguishable pattern of gravity and magnetic anomalies that reflect these properties.

  13. Principal facts for gravity stations collected in 2010 from White Pine and Lincoln Counties, east-central Nevada

    USGS Publications Warehouse

    Mankinen, Edward A.; McKee, Edwin H.

    2011-01-01

    Increasing demands on the Colorado River system within the arid Southwestern United States have focused attention on finding new, alternative sources of water. Particular attention is being paid to the eastern Great Basin, where important ground-water systems occur within a regionally extensive sequence of Paleozoic carbonate rocks and in the Cenozoic basin-fill deposits that occur throughout the region. Geophysical investigations to characterize the geologic framework of aquifers in eastern Nevada and western Utah began in a series of cooperative agreements between the U.S. Geological Survey and the Southern Nevada Water Authority in 2003. These studies were intended to better understand the formation of basins, define their subsurface shape and depth, and delineate structures that may impede or enhance groundwater flow. We have combined data from gravity stations established during the current study with previously available data to produce an up-to-date isostatic-gravity map of the study area, using a gravity inversion method to calculate depths to pre-Cenozoic basement rock and to estimate alluvial/volcanic fill in the valleys.

  14. Precision gravity studies at Cerro Prieto: a progress report

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Grannell, R.B.; Kroll, R.C.; Wyman, R.M.

    A third and fourth year of precision gravity data collection and reduction have now been completed at the Cerro Prieto geothermal field. In summary, 66 permanently monumented stations were occupied between December and April of 1979 to 1980 and 1980 to 1981 by a LaCoste and Romberg gravity meter (G300) at least twice, with a minimum of four replicate values obtained each time. Station 20 alternate, a stable base located on Cerro Prieto volcano, was used as the reference base for the third year and all the stations were tied to this base, using four to five hour loops. Themore » field data were reduced to observed gravity values by (1) multiplication with the appropriate calibration factor; (2) removal of calculated tidal effects; (3) calculation of average values at each station, and (4) linear removal of accumulated instrumental drift which remained after carrying out the first three reductions. Following the reduction of values and calculation of gravity differences between individual stations and the base stations, standard deviations were calculated for the averaged occupation values (two to three per station). In addition, pooled variance calculations were carried out to estimate precision for the surveys as a whole.« less

  15. Atom-chip-based quantum gravimetry for the precise determination of absolute gravity

    NASA Astrophysics Data System (ADS)

    Abend, Sven; Schubert, Christian; Ertmer, Wolfgang; Rasel, Ernst

    2017-04-01

    We present a novel technique for the precise measurement of absolute local gravity with a quantum gravimeter based on an atom chip. Atom interferometry utilizes the interference of matter waves interrogated by laser light to read out inertial forces. Today's generation of these devices typically operate with test mass samples, that consists of ensembles of laser cooled atoms. Their performance is limited by the velocity spread and finite-size of the test masses that impose systematic uncertainties at the level of a few μGal [1]. Rather than laser cooled atoms we employ quantum degenerate ensembles, so called Bose-Einstein condensates [2], as ultra-sensitive probes for gravity. These sources offer unique properties that will allow to overcome the current limitations in the next generation of sensors. Furthermore, atom-chip technology offers the possibility to generate Bose-Einstein condensates in a fast and reliable way. We present a lab-based prototype that uses the atom chip itself to retro-reflect the interrogation laser and thus serves as inertial reference inside the vacuum [3]. With this setup, it is possible to demonstrate all necessary steps to measure gravity, including the preparation of the source, spanning an interferometer as well as the detection of the output signal. All steps are pursued on a baseline of 1 cm right below the atom chip and to analyze relevant systematic effects. In the framework of the center of excellence geoQ a next generation device is under construction at the Institut für Quantenoptik, that will target for in-field measurements. This device will feature a state-of-the-art atom-chip source with a high-flux of ultra-cold atoms at a repetition rate of 1-2 Hz [4]. The device will be characterized in cooperation with the Müller group at the Institut für Erdmessung the sensor and finally employed in a campaign to measure the Fennoscandian uplift at the level of 1 μGal. The presented work is supported by the CRC 1227 DQ-mat, the

  16. Zero-gravity open-type urine receptacle

    NASA Technical Reports Server (NTRS)

    Girala, A. S.

    1972-01-01

    The development of the zero-gravity open-type urine receptacle used in the Apollo command module is described. This type receptacle eliminates the need for a cuff-type urine collector or for the penis to circumferentially contact the receptacle in order to urinate. This device may be used in a gravity environment, varying from zero gravity to earth gravity, such as may be experienced in a space station or space base.

  17. Gravity and the geoid in the Nepal Himalaya

    NASA Technical Reports Server (NTRS)

    Bilham, Roger

    1992-01-01

    Materials within the Himalaya are rising due to convergence between India and Asia. If the rate of erosion is comparable to the rate of uplift the mean surface elevation will remain constant. Any slight imbalance in these two processes will lead to growth or attrition of the Himalaya. The process of uplift of materials within the Himalaya coupled with surface erosion is similar to the advance of a glacier into a region of melting. If the melting rate exceeds the rate of downhill motion of the glacier then the terminus of the glacier will receed up-valley despite the downhill motion of the bulk of the glacier. Thus although buried rocks, minerals and surface control points in the Himalaya are undoubtably rising, the growth or collapse of the Himalaya depends on the erosion rate which is invisible to geodetic measurements. Erosion rates are currently estimated from suspended sediment loads in rivers in the Himalaya. These typically underestimate the real erosion rate since bed-load is not measured during times of heavy flood, and it is difficult to integrate widely varying suspended load measurements over many years. An alternative way to measure erosion rate is to measure the rate of change of gravity in a region of uplift. If a control point moves vertically it should be accompanied by a reduction in gravity as the point moves away from the Earth's center of mass. There is a difference in the change of gravity between uplift with and without erosion corresponding to the difference between the free-air gradient and the gradient in the acceleration due to gravity caused by a corresponding thickness of rock. Essentially gravity should change precisely in accord with a change in elevation of the point in a free-air gradient if erosion equals uplift rate. We were funded by NASA to undertake a measurement of absolute gravity simultaneously with measurements of GPS height within the Himalaya. Since both absolute gravity and time are known in an absolute sense to 1 part in

  18. Tethered gravity laboratories study

    NASA Technical Reports Server (NTRS)

    Lucchetti, F.

    1989-01-01

    The use is studied of tether systems to improve the lowest possible steady gravity level on the Space Station. Particular emphasis is placed by the microgravity community on the achievement of high quality microgravity conditions. The tether capability is explored for active control of the center of gravity and the analysis of possible tethered configurations.

  19. Time-dependent gravity in Southern California, May 1974 to April 1979

    NASA Technical Reports Server (NTRS)

    Whitcomb, J. H.; Franzen, W. O.; Given, J. W.; Pechmann, J. C.; Ruff, L. J.

    1980-01-01

    The Southern California gravity survey, begun in May 1974 to obtain high spatial and temporal density gravity measurements to be coordinated with long-baseline three dimensional geodetic measurements of the Astronomical Radio Interferometric Earth Surveying project, is presented. Gravity data was obtained from 28 stations located in and near the seismically active San Gabriel section of the Southern California Transverse Ranges and adjoining San Andreas Fault at intervals of one to two months using gravity meters relative to a base station standard meter. A single-reading standard deviation of 11 microGal is obtained which leads to a relative deviation of 16 microGal between stations, with data averaging reducing the standard error to 2 to 3 microGal. The largest gravity variations observed are found to correlate with nearby well water variations and smoothed rainfall levels, indicating the importance of ground water variations to gravity measurements. The largest earthquake to occur during the survey, which extended to April, 1979, is found to be accompanied in the station closest to the earthquake by the largest measured gravity changes that cannot be related to factors other than tectonic distortion.

  20. Reduced Gravity Zblan Optical Fiber

    NASA Technical Reports Server (NTRS)

    Tucker, Dennis S.; Workman, Gary L.; Smith, Guy A.

    2000-01-01

    Two optical fiber pullers have been designed for pulling ZBLAN optical fiber in reduced gravity. One fiber puller was designed, built and flown on board NASA's KC135 reduced gravity aircraft. A second fiber puller has been designed for use on board the International Space Station.

  1. Final report on the Seventh International Comparison of Absolute Gravimeters (ICAG 2005)

    USGS Publications Warehouse

    Jiang, Z.; Francis, O.; Vitushkin, L.; Palinkas, V.; Germak, A.; Becker, M.; D'Agostino, G.; Amalvict, M.; Bayer, R.; Bilker-Koivula, M.; Desogus, S.; Faller, J.; Falk, R.; Hinderer, J.; Gagnon, C.; Jakob, T.; Kalish, E.; Kostelecky, J.; Lee, C.; Liard, J.; Lokshyn, Y.; Luck, B.; Makinen, J.; Mizushima, S.; Le, Moigne N.; Origlia, C.; Pujol, E.R.; Richard, P.; Robertsson, L.; Ruess, D.; Schmerge, D.; Stus, Y.; Svitlov, S.; Thies, S.; Ullrich, C.; Van Camp, M.; Vitushkin, A.; Ji, W.; Wilmes, H.

    2011-01-01

    The Bureau International des Poids et Mesures (BIPM), S??vres, France, hosted the 7th International Comparison of Absolute Gravimeters (ICAG) and the associated Relative Gravity Campaign (RGC) from August to September 2005. ICAG 2005 was prepared and performed as a metrological pilot study, which aimed: To determine the gravity comparison reference values; To determine the offsets of the absolute gravimeters; and As a pilot study to accumulate experience for the CIPM Key Comparisons. This document presents a complete and extensive review of the technical protocol and data processing procedures. The 1st ICAG-RGC comparison was held at the BIPM in 1980-1981 and since then meetings have been organized every 4 years. In this paper, we present an overview of how the meeting was organized, the conditions of BIPM gravimetric sites, technical specifications, data processing strategy and an analysis of the final results. This 7th ICAG final report supersedes all previously published reports. Readings were obtained from participating instruments, 19 absolute gravimeters and 15 relative gravimeters. Precise levelling measurements were carried out and all measurements were performed on the BIPM micro-gravity network which was specifically designed for the comparison. ?? 2011 BIPM & IOP Publishing Ltd.

  2. Maui Gravity and Soil Gas Surveys

    DOE Data Explorer

    John Akerley

    2010-04-01

    Contains a ground-based gravity survey of South Maui and a series of soil CO2 flux and temperature surveys encompassing Maui and the Big Island. The gravity survey was collected from approximately 284 km2 and consisted of 400 gravity stations with 400 m spacing. Locations were derived with full DGPS. Station and line location, Complete Bouger Anomaly, first vertical derivative and horizontal gradient maps were calculated and produced. The soil CO2 flux and temperature surveys were conducted on the islands of Hawaii and Maui in April and July 2010. Average soil temperatures were measured over 10 cm depth using a hand-held thermocouple. Soil CO2 fluxes were measured using a portable accumulation chamber instrument.

  3. Residual Gravity Changes at Kilauea: 1977-2003

    NASA Astrophysics Data System (ADS)

    Eggers, A. A.

    2006-12-01

    Microgravity surveys on volcanoes provide insight into the mechanisms of volcanic eruptions. Typically gravity is measured repeatedly over a dense network of stations using one or more meters. Raw gravity measurements corrected for effects of earthtides, instrumental drift, and concurrent elevation changes give residual gravity. Successive surveys give residual gravity changes reflecting mass redistributions within volcanoes affected by dynamic magmatic and/or hydrothermal systems. At Kilauea Volcano a network about 65 stations was most recently reoccupied by Johnson and Eggers in October and November 2003, and by Johnson in 1999 and 1998. Data from 1977 and 1981 surveys (by H.V.O. staff) are included in this study. The reduced gravity data (precision about 10 microgals) show residual gravity has consistently and steadily increased by more than 300 microgals since 1977 in a semicircular area several hundred meters in diameter, centered on the SE rim of Halemaumau Crater. Residual gravity change anomalies for the intervals 1999-2003, 1981-1999, and 1977-1981 have respective amplitudes of approximately 100, 140, and 100 microgals. Because of lower station density and lack of station-to-station continuity over time anomalies representing the two earlier intervals are less well defined. Half-widths at half-heights of the anomalies from each interval indicate a source depths for the masses producing the gravity change of 550 to 700 m below the caldera floor. Mogi point mass interpretations, assuming a 600 m depth, using the 100, 140, and 100 microgal respective amplitudes suggest a cumulative mass addition of about 18x10^9 kg since 1977. Mass has apparently been added to a shallow chamber below the caldera floor at 0.7x10^9 kg/yr on the average throughout most of the Pu'u `O'o eruption. From 1983-2002 magma throughput in the Kilauea/Pu'u `O'o system has averaged about 3.5x10^1^1kg/yr (Sutton et al 2003). This magma throughput represents only 83-87% of the primary magma

  4. Somigliana-Pizzetti gravity: the international gravity formula accurate to the sub-nanoGal level

    NASA Astrophysics Data System (ADS)

    Ardalan, A. A.; Grafarend, E. W.

    2001-09-01

    The Somigliana-Pizzetti gravity field (the International gravity formula), namely the gravity field of the level ellipsoid (the International Reference Ellipsoid), is derived to the sub-nanoGal accuracy level in order to fulfil the demands of modern gravimetry (absolute gravimeters, super conducting gravimeters, atomic gravimeters). Equations (53), (54) and (59) summarise Somigliana-Pizzetti gravity o({,u) as a function of Jacobi spheroidal latitude { and height u to the order ™(10m10 Gal), and o(B,H) as a function of Gauss (surface normal) ellipsoidal latitude B and height H to the order ™(10m10 Gal) as determined by GPS (`global problem solver'). Within the test area of the state of Baden-Württemberg, Somigliana-Pizzetti gravity disturbances of an average of 25.452 mGal were produced. Computer programs for an operational application of the new international gravity formula with (L,B,H) or (u,{,u) coordinate inputs to a sub-nanoGal level of accuracy are available on the Internet.

  5. Space Station

    NASA Image and Video Library

    1970-01-01

    This is an illustration of the Space Base concept. In-house work of the Marshall Space Flight Center, as well as a Phase B contract with the McDornel Douglas Astronautics Company, resulted in a preliminary design for a space station in 1969 and l970. The Marshall-McDonnel Douglas approach envisioned the use of two common modules as the core configuration of a 12-man space station. Each common module was 33 feet in diameter and 40 feet in length and provided the building blocks, not only for the space station, but also for a 50-man space base. Coupled together, the two modules would form a four-deck facility: two decks for laboratories and two decks for operations and living quarters. Zero-gravity would be the normal mode of operation, although the station would have an artificial-gravity capability. This general-purpose orbital facility was to provide wide-ranging research capabilities. The design of the facility was driven by the need to accommodate a broad spectrum of activities in support of astronomy, astrophysics, aerospace medicine, biology, materials processing, space physics, and space manufacturing. To serve the needs of Earth observations, the station was to be placed in a 242-nautical-mile orbit at a 55-degree inclination. An Intermediate-21 vehicle (comprised of Saturn S-IC and S-II stages) would have launched the station in 1977.

  6. Space Station

    NASA Image and Video Library

    1969-01-01

    This picture illustrates a concept of a 33-Foot-Diameter Space Station Leading to a Space Base. In-house work of the Marshall Space Flight Center, as well as a Phase B contract with the McDornel Douglas Astronautics Company, resulted in a preliminary design for a space station in 1969 and l970. The Marshall-McDonnel Douglas approach envisioned the use of two common modules as the core configuration of a 12-man space station. Each common module was 33 feet in diameter and 40 feet in length and provided the building blocks, not only for the space station, but also for a 50-man space base. Coupled together, the two modules would form a four-deck facility: two decks for laboratories and two decks for operations and living quarters. Zero-gravity would be the normal mode of operation, although the station would have an artificial gravity capability. This general-purpose orbital facility was to provide wide-ranging research capabilities. The design of the facility was driven by the need to accommodate a broad spectrum of activities in support of astronomy, astrophysics, aerospace medicine, biology, materials processing, space physics, and space manufacturing. To serve the needs of Earth observations, the station was to be placed in a 242-nautical-mile orbit at a 55-degree inclination. An Intermediate-21 vehicle (comprised of Saturn S-IC and S-II stages) would have launched the station in 1977.

  7. Isostatic gravity map of the Monterey 30 x 60 minute quadrangle and adjacent areas, California

    USGS Publications Warehouse

    Langenheim, V.E.; Stiles, S.R.; Jachens, R.C.

    2002-01-01

    The digital dataset consists of one file (monterey_100k.iso) containing 2,385 gravity stations. The file, monterey_100k.iso, contains the principal facts of the gravity stations, with one point coded per line. The format of the data is described below. Each gravity station has a station name, location (latitude and longitude, NAD27 projection), elevation, and an observed gravity reading. The data are on the IGSN71 datum and the reference ellipsoid is the Geodetic Reference System 1967 (GRS67). The free-air gravity anomalies were calculated using standard formulas (Telford and others, 1976). The Bouguer, curvature, and terrain corrections were applied to the free-air anomaly at each station to determine the complete Bouguer gravity anomalies at a reduction density of 2.67 g/cc. An isostatic correction was then applied to remove the long-wavelength effect of deep crustal and/or upper mantle masses that isostatically support regional topography.

  8. From Hubble's NGSL to Absolute Fluxes

    NASA Technical Reports Server (NTRS)

    Heap, Sara R.; Lindler, Don

    2012-01-01

    Hubble's Next Generation Spectral Library (NGSL) consists of R-l000 spectra of 374 stars of assorted temperature, gravity, and metallicity. Each spectrum covers the wavelength range, 0.18-1.00 microns. The library can be viewed and/or downloaded from the website, http://archive.stsci.edu/prepds/stisngsll. Stars in the NGSL are now being used as absolute flux standards at ground-based observatories. However, the uncertainty in the absolute flux is about 2%, which does not meet the requirements of dark-energy surveys. We are therefore developing an observing procedure that should yield fluxes with uncertainties less than 1 % and will take part in an HST proposal to observe up to 15 stars using this new procedure.

  9. Mobile quantum gravity sensor with unprecedented stability

    NASA Astrophysics Data System (ADS)

    Freier, C.; Hauth, M.; Schkolnik, V.; Leykauf, B.; Schilling, M.; Wziontek, H.; Scherneck, H.-G.; Müller, J.; Peters, A.

    2016-06-01

    Changes of surface gravity on Earth are of great interest in geodesy, earth sciences and natural resource exploration. They are indicative of Earth system's mass redistributions and vertical surface motion, and are usually measured with falling corner-cube- and superconducting gravimeters (FCCG and SCG). Here we report on absolute gravity measurements with a mobile quantum gravimeter based on atom interferometry. The measurements were conducted in Germany and Sweden over periods of several days with simultaneous SCG and FCCG comparisons. They show the best-reported performance of mobile atomic gravimeters to date with an accuracy of 39nm/s2, long-term stability of 0.5nm/s2 and short-term noise of 96nm/s2/√Hz. These measurements highlight the unique properties of atomic sensors. The achieved level of performance in a transportable instrument enables new applications in geodesy and related fields, such as continuous absolute gravity monitoring with a single instrument under rough environmental conditions.

  10. The temperatures, abundances and gravities of F dwarf stars.

    NASA Technical Reports Server (NTRS)

    Bell, R. A.

    1971-01-01

    Theoretical colors computed from laboratory line data and from model stellar atmospheres have been used to interpret the colors of about 150 F and early G dwarfs. Effective temperatures have been derived from the H-beta index and from R-I, abundances have been obtained from m(sub 1) and from b-y, and gravities have been obtained from c(sub 1) and from b-y. The effective temperatures and gravities are in good agreement with values obtained from spectral scans. Absolute magnitudes have been obtained from the effective temperatures and gravities, the latter being used with assumed stellar masses to yield radii. The present results provide theoretical justification of the empirical formulas given by Crawford and by Stroemgren for the determination of absolute magnitudes and abundances from uvby photometry.

  11. Logamediate Inflation in f(T) Teleparallel Gravity

    NASA Astrophysics Data System (ADS)

    Rezazadeh, Kazem; Abdolmaleki, Asrin; Karami, Kayoomars

    2017-02-01

    We study logamediate inflation in the context of f(T) teleparallel gravity. f(T)-gravity is a generalization of the teleparallel gravity which is formulated on the Weitzenbock spacetime, characterized by the vanishing curvature tensor (absolute parallelism) and the non-vanishing torsion tensor. We consider an f(T)-gravity model which is sourced by a canonical scalar field. Assuming a power-law f(T) function in the action, we investigate an inflationary universe with a logamediate scale factor. Our results show that, although logamediate inflation is completely ruled out by observational data in the standard inflationary scenario based on Einstein gravity, it can be compatible with the 68% confidence limit joint region of Planck 2015 TT,TE,EE+lowP data in the framework of f(T)-gravity.

  12. Gravity Survey of the Carson Sink - Data and Maps

    DOE Data Explorer

    Faulds, James E.

    2013-12-31

    A detailed gravity survey was carried out for the entire Carson Sink in western Nevada (Figure 1) through a subcontract to Zonge Engineering, Inc. The Carson Sink is a large composite basin containing three known, blind high-temperature geothermal systems (Fallon Airbase, Stillwater, and Soda Lake). This area was chosen for a detailed gravity survey in order to characterize the gravity signature of the known geothermal systems and to identify other potential blind systems based on the structural setting indicated by the gravity data. Data: Data were acquired at approximately 400, 800, and 1600 meter intervals for a total of 1,243 stations. The project location and station location points are presented in Figure 14. The station distribution for this survey was designed to complete regional gravity coverage in the Carson Sink area without duplication of available public and private gravity coverage. Gravity data were acquired using a Scintrex CG-5 gravimeter and a LaCoste and Romberg (L&R) Model-G gravimeter. The CG-5 gravity meter has a reading resolution of 0.001 milligals and a typical repeatability of less than 0.005 milligals. The L&R gravity meter has a reading resolution of 0.01 milligals and a typical repeatability of 0.02 milligals. The basic processing of gravimeter readings to calculate through to the Complete Bouguer Anomaly was made using the Gravity and Terrain Correction software version 7.1 for Oasis Montaj by Geosoft LTD. Results: The gravity survey of the Carson Sink yielded the following products. Project location and station location map (Figure 14). Complete Bouguer Anomaly @ 2.67 gm/cc reduction density. Gravity Complete Bouguer Anomaly at 2.50 g/cc Contour Map (Figure 15). Gravity Horizontal Gradient Magnitude Shaded Color Contour Map. Gravity 1st Vertical Derivative Color Contour Map. Interpreted Depth to Mesozoic Basement (Figure 16), incorporating drill-hole intercept values. Preliminary Interpretation of Results: The Carson Sink is a

  13. Statistical analysis of mesospheric gravity waves over King Sejong Station, Antarctica (62.2°S, 58.8°W)

    NASA Astrophysics Data System (ADS)

    Kam, Hosik; Jee, Geonhwa; Kim, Yong; Ham, Young-bae; Song, In-Sun

    2017-03-01

    We have investigated the characteristics of mesospheric short period (<1 h) gravity waves which were observed with all-sky images of OH Meinel band and OI 557 nm airglows over King Sejong Station (KSS) (62.22°S, 58.78°W) during a period of 2008-2015. By applying 2-dimensional FFT to time differenced images, we derived horizontal wavelengths, phase speeds, and propagating directions (188 and 173 quasi-monochromatic waves from OH and OI airglow images, respectively). The majority of the observed waves propagated predominantly westward, implying that eastward waves were filtered out by strong eastward stratospheric winds. In order to obtain the intrinsic properties of the observed waves, we utilized winds simultaneously measured by KSS Meteor Radar and temperatures from Aura Microwave Limb Sounder (MLS). More than half the waves propagated horizontally, as waves were in Doppler duct or evanescent in the vertical direction. This might be due to strong eastward background wind field in the mesosphere over KSS. For freely propagating waves, the vertical wavelengths were in the interquartile range of 9-33 km with a median value of 15 km. The vertical wavelengths are shorter than those observed at Halley station (76°S, 27°W) where the majority of the observed waves were freely propagating. The difference in the wave propagating characteristics between KSS and Halley station suggests that gravity waves may affect mesospheric dynamics in this part of the Antarctic Peninsula more strongly than over the Antarctic continent. Furthermore, strong wind shear over KSS played an important role in changing the vertical wavenumbers as the waves propagated upward between two airglow layers (87 and 96 km).

  14. Principal Facts for Gravity Data Collected in Wisconsin: A Web Site and CD-ROM for Distribution of Data

    USGS Publications Warehouse

    Snyder, Stephen L.; Geister, Daniel W.; Daniels, David L.; Ervin, C. Patrick

    2004-01-01

    Principal facts for 40,488 gravity stations covering the entire state of Wisconsin are presented here in digital form. This is a compilation of previously published data collected between 1948 and 1992 from numerous sources, along with over 10,000 new gravity stations collected by the USGS since 1999. Also included are 550 gravity stations from previously unpublished sources. Observed gravity and complete-Bouguer gravity anomaly data for this statewide compilation are included here. Altogether, 14 individual surveys are presented here.

  15. Development of a network RTK positioning and gravity-surveying application with gravity correction using a smartphone.

    PubMed

    Kim, Jinsoo; Lee, Youngcheol; Cha, Sungyeoul; Choi, Chuluong; Lee, Seongkyu

    2013-07-12

    This paper proposes a smartphone-based network real-time kinematic (RTK) positioning and gravity-surveying application (app) that allows semi-real-time measurements using the built-in Bluetooth features of the smartphone and a third-generation or long-term evolution wireless device. The app was implemented on a single smartphone by integrating a global navigation satellite system (GNSS) controller, a laptop, and a field-note writing tool. The observation devices (i.e., a GNSS receiver and relative gravimeter) functioned independently of this system. The app included a gravity module, which converted the measured relative gravity reading into an absolute gravity value according to tides; meter height; instrument drift correction; and network adjustments. The semi-real-time features of this app allowed data to be shared easily with other researchers. Moreover, the proposed smartphone-based gravity-survey app was easily adaptable to various locations and rough terrain due to its compact size.

  16. Global detailed gravimetric geoid. [based on gravity model derived from satellite tracking and surface gravity data

    NASA Technical Reports Server (NTRS)

    Vincent, S.; Marsh, J. G.

    1973-01-01

    A global detailed gravimetric geoid has been computed by combining the Goddard Space Flight Center GEM-4 gravity model derived from satellite and surface gravity data and surface 1 deg-by-1 deg mean free air gravity anomaly data. The accuracy of the geoid is + or - 2 meters on continents, 5 to 7 meters in areas where surface gravity data are sparse, and 10 to 15 meters in areas where no surface gravity data are available. Comparisons have been made with the astrogeodetic data provided by Rice (United States), Bomford (Europe), and Mather (Australia). Comparisons have also been carried out with geoid heights derived from satellite solutions for geocentric station coordinates in North America, the Caribbean, Europe, and Australia.

  17. Bouguer gravity map of Indonesia

    NASA Astrophysics Data System (ADS)

    Green, R.; Adkins, J. S.; Harrington, H. J.; Untung, M.

    1981-01-01

    A Bouguer gravity map of Indonesia on Mercator projection at a scale of 1: 5,000,000 and with a contour interval 20 mGal has been prepared over the past few years as part of a joint research program of the Geological Survey of Indonesia and the University of New England, Armidale. A new base station network was set up throughout Indonesia and tied to the IGSN stations at Sydney and Singapore. A discussion of the gravity features and the tectonic implications are given. The map is obtainable, in folded form only, from the Publications Department, University of New England, Armidale, N.S.W., Australia 2351 for $ A 5.- plus postage.

  18. Gravity and the geoid in the Nepal Himalaya

    NASA Technical Reports Server (NTRS)

    Bilham, Roger

    1992-01-01

    Materials within the Himalaya are rising due to convergence between India and Asia. If the rate of erosion is comparable to the rate of uplift, the mean surface elevation will remain constant. Any slight imbalance in these two processes will lead to growth or attrition of the Himalaya. Although buried rocks, minerals and surface control points in the Himalaya are undoubtably rising, the growth or collapse or the Himalaya depends on the erosion rate which is invisible to geodetic measurements. A way to measure erosion rate is to measure the rate of change of gravity in a region of uplift. Essentially gravity should change precisely in accord with a change in elevation of the point in a free air gradient if erosion equals uplift rate. A measurement of absolute gravity was made simultaneously with measurements of GPS height within the Himalaya. Absolute gravity is estimated from the change in velocity per unit distance of a falling corner cube in a vacuum. Time is measured with an atomic clock and the unit distance corresponds to the wavelength of an iodine stabilized laser. An experiment undertaken in the Himalaya in 1991 provide a site description also with a instrument description.

  19. Intraspecific differences in bacterial responses to modelled reduced gravity

    NASA Technical Reports Server (NTRS)

    Baker, P. W.; Leff, L. G.

    2005-01-01

    AIMS: Bacteria are important residents of water systems, including those of space stations which feature specific environmental conditions, such as lowered effects of gravity. The purpose of this study was to compare responses with modelled reduced gravity of space station, water system bacterial isolates with other isolates of the same species. METHODS AND RESULTS: Bacterial isolates, Stenotrophomonas paucimobilis and Acinetobacter radioresistens, originally recovered from the water supply aboard the International Space Station (ISS) were grown in nutrient broth under modelled reduced gravity. Their growth was compared with type strains S. paucimobilis ATCC 10829 and A. radioresistens ATCC 49000. Acinetobacter radioresistens ATCC 49000 and the two ISS isolates showed similar growth profiles under modelled reduced gravity compared with normal gravity, whereas S. paucimobilis ATCC 10829 was negatively affected by modelled reduced gravity. CONCLUSIONS: These results suggest that microgravity might have selected for bacteria that were able to thrive under this unusual condition. These responses, coupled with impacts of other features (such as radiation resistance and ability to persist under very oligotrophic conditions), may contribute to the success of these water system bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: Water quality is a significant factor in many environments including the ISS. Efforts to remove microbial contaminants are likely to be complicated by the features of these bacteria which allow them to persist under the extreme conditions of the systems.

  20. Effect of reduced gravity on the preferred walk-run transition speed

    NASA Technical Reports Server (NTRS)

    Kram, R.; Domingo, A.; Ferris, D. P.

    1997-01-01

    We investigated the effect of reduced gravity on the human walk-run gait transition speed and interpreted the results using an inverted-pendulum mechanical model. We simulated reduced gravity using an apparatus that applied a nearly constant upward force at the center of mass, and the subjects walked and ran on a motorized treadmill. In the inverted pendulum model for walking, gravity provides the centripetal force needed to keep the pendulum in contact with the ground. The ratio of the centripetal and gravitational forces (mv2/L)/(mg) reduces to the dimensionless Froude number (v2/gL). Applying this model to a walking human, m is body mass, v is forward velocity, L is leg length and g is gravity. In normal gravity, humans and other bipeds with different leg lengths all choose to switch from a walk to a run at different absolute speeds but at approximately the same Froude number (0.5). We found that, at lower levels of gravity, the walk-run transition occurred at progressively slower absolute speeds but at approximately the same Froude number. This supports the hypothesis that the walk-run transition is triggered by the dynamics of an inverted-pendulum system.

  1. Development of a Network RTK Positioning and Gravity-Surveying Application with Gravity Correction Using a Smartphone

    PubMed Central

    Kim, Jinsoo; Lee, Youngcheol; Cha, Sungyeoul; Choi, Chuluong; Lee, Seongkyu

    2013-01-01

    This paper proposes a smartphone-based network real-time kinematic (RTK) positioning and gravity-surveying application (app) that allows semi-real-time measurements using the built-in Bluetooth features of the smartphone and a third-generation or long-term evolution wireless device. The app was implemented on a single smartphone by integrating a global navigation satellite system (GNSS) controller, a laptop, and a field-note writing tool. The observation devices (i.e., a GNSS receiver and relative gravimeter) functioned independently of this system. The app included a gravity module, which converted the measured relative gravity reading into an absolute gravity value according to tides; meter height; instrument drift correction; and network adjustments. The semi-real-time features of this app allowed data to be shared easily with other researchers. Moreover, the proposed smartphone-based gravity-survey app was easily adaptable to various locations and rough terrain due to its compact size. PMID:23857258

  2. Techniques, analysis, and noise in a Salt Lake Valley 4D gravity experiment

    USGS Publications Warehouse

    Gettings, P.; Chapman, D.S.; Allis, R.

    2008-01-01

    Repeated high-precision gravity measurements using an automated gravimeter and analysis of time series of 1-Hz samples allowed gravity measurements to be made with an accuracy of 5 ??Gal or better. Nonlinear instrument drift was removed using a new empirical staircase function built from multiple station loops. The new technique was developed between March 1999 and September 2000 in a pilot study conducted in the southern Salt Lake Valley along an east-west profile of eight stations from the Wasatch Mountains to the Jordan River. Gravity changes at eight profile stations were referenced to a set of five stations in the northern Salt Lake Valley, which showed residual signals of <10 ??Gal in amplitude, assuming a reference station near the Great Salt Lake to be stable. Referenced changes showed maximum amplitudes of -40 through +40 ??Gal at profile stations, with minima in summer 1999, maxima in winter 1999-2000, and some decrease through summer 2000. Gravity signals were likely a composite of production-induced changes monitored by well-water levels, elevation changes, precipitation-induced vadose-zone changes, and local irrigation effects for which magnitudes were estimated quantitatively. ?? 2008 Society of Exploration Geophysicists. All rights reserved.

  3. Preprocessing of gravity gradients at the GOCE high-level processing facility

    NASA Astrophysics Data System (ADS)

    Bouman, Johannes; Rispens, Sietse; Gruber, Thomas; Koop, Radboud; Schrama, Ernst; Visser, Pieter; Tscherning, Carl Christian; Veicherts, Martin

    2009-07-01

    One of the products derived from the gravity field and steady-state ocean circulation explorer (GOCE) observations are the gravity gradients. These gravity gradients are provided in the gradiometer reference frame (GRF) and are calibrated in-flight using satellite shaking and star sensor data. To use these gravity gradients for application in Earth scienes and gravity field analysis, additional preprocessing needs to be done, including corrections for temporal gravity field signals to isolate the static gravity field part, screening for outliers, calibration by comparison with existing external gravity field information and error assessment. The temporal gravity gradient corrections consist of tidal and nontidal corrections. These are all generally below the gravity gradient error level, which is predicted to show a 1/ f behaviour for low frequencies. In the outlier detection, the 1/ f error is compensated for by subtracting a local median from the data, while the data error is assessed using the median absolute deviation. The local median acts as a high-pass filter and it is robust as is the median absolute deviation. Three different methods have been implemented for the calibration of the gravity gradients. All three methods use a high-pass filter to compensate for the 1/ f gravity gradient error. The baseline method uses state-of-the-art global gravity field models and the most accurate results are obtained if star sensor misalignments are estimated along with the calibration parameters. A second calibration method uses GOCE GPS data to estimate a low-degree gravity field model as well as gravity gradient scale factors. Both methods allow to estimate gravity gradient scale factors down to the 10-3 level. The third calibration method uses high accurate terrestrial gravity data in selected regions to validate the gravity gradient scale factors, focussing on the measurement band. Gravity gradient scale factors may be estimated down to the 10-2 level with this

  4. Combustion and fires in low gravity

    NASA Technical Reports Server (NTRS)

    Friedman, Robert

    1994-01-01

    Fire safety always receives priority attention in NASA mission designs and operations, with emphasis on fire prevention and material acceptance standards. Recently, interest in spacecraft fire-safety research and development has increased because improved understanding of the significant differences between low-gravity and normal-gravity combustion suggests that present fire-safety techniques may be inadequate or, at best, non-optimal; and the complex and permanent orbital operations in Space Station Freedom demand a higher level of safety standards and practices. This presentation outlines current practices and problems in fire prevention and detection for spacecraft, specifically the Space Station Freedom's fire protection. Also addressed are current practices and problems in fire extinguishment for spacecraft.

  5. Experiments to ensure Space Station fire safety - A challenge

    NASA Technical Reports Server (NTRS)

    Youngblood, W. W.; Seiser, K. M.

    1988-01-01

    Three experiments have been formulated in order to address prominent fire safety requirements aboard the NASA Space Shuttle; these experiments are to be conducted as part of a Space Station-based Technology Development Mission for the growth phase of Space Station construction and operation. The experiments are: (1) an investigation of the flame-spread rate and combustion-product evolution in the burning of typical spacecraft materials in low gravity; (2) an evaluation of the interaction of fires and candidate fire extinguishers in low gravity; and (3) an investigation of the persistence and propagation of smoldering and deep-seated combustion in low gravity.

  6. Sub µGal Absolute Gravity Measurements with a Transportable Quantum Gravimeter

    NASA Astrophysics Data System (ADS)

    Desruelle, B.; Vermeulen, P.; Menoret, V.; Landragin, A.; Bouyer, P.; Le Moigne, N.; Gabalda, G.; Bonvalot, S.

    2017-12-01

    This paper presents a review of the last two years of operation of the first unit of the Absolute Quantum Gravimeter (AQG). The AQG is an industry-grade commercial gravimeter, which validates the feasibility to develop a matter-wave gravimeter as a transportable turn-key device. We will discuss the stability of the absolute measurement of g and demonstrate the capability of our instrument to achieve a sensitivity better than 1 µGal in various types of environment. We will in particular comment on the last measurement campaigns and comparisons performed by the AQG which have validated the ease of use and the robustness of the sensor. This paper will also present the status of the development of the field version of the AQG designed to be compatible with outdoor operation.

  7. Statistical analysis of gravity waves characteristics observed by airglow imaging at Syowa Station (69S, 39E), Antarctica

    NASA Astrophysics Data System (ADS)

    Matsuda, Takashi S.; Nakamura, Takuji; Shiokawa, Kazuo; Tsutsumi, Masaki; Suzuki, Hidehiko; Ejiri, Mitsumu K.; Taguchi, Makoto

    Atmospheric gravity waves (AGWs), which are generated in the lower atmosphere, transport significant amount of energy and momentum into the mesosphere and lower thermosphere and cause the mean wind accelerations in the mesosphere. This momentum deposit drives the general circulation and affects the temperature structure. Among many parameters to characterize AGWs, horizontal phase velocity is very important to discuss the vertical propagation. Airglow imaging is a useful technique for investigating the horizontal structures of AGWs at around 90 km altitude. Recently, there are many reports about statistical characteristics of AGWs observed by airglow imaging. However, comparison of these results obtained at various locations is difficult because each research group uses its own method for extracting and analyzing AGW events. We have developed a new statistical analysis method for obtaining the power spectrum in the horizontal phase velocity domain from airglow image data, so as to deal with huge amounts of imaging data obtained on different years and at various observation sites, without bias caused by different event extraction criteria for the observer. This method was applied to the data obtained at Syowa Station, Antarctica, in 2011 and compared with a conventional event analysis in which the phase fronts were traced manually in order to estimate horizontal characteristics. This comparison shows that our new method is adequate to deriving the horizontal phase velocity characteristics of AGWs observed by airglow imaging technique. We plan to apply this method to airglow imaging data observed at Syowa Station in 2002 and between 2008 and 2013, and also to the data observed at other stations in Antarctica (e.g. Rothera Station (67S, 68W) and Halley Station (75S, 26W)), in order to investigate the behavior of AGWs propagation direction and source distribution in the MLT region over Antarctica. In this presentation, we will report interim analysis result of the data

  8. Mapping experiment with space station

    NASA Technical Reports Server (NTRS)

    Wu, S. S. C.

    1986-01-01

    Mapping of the Earth from space stations can be approached in two areas. One is to collect gravity data for defining topographic datum using Earth's gravity field in terms of spherical harmonics. The other is to search and explore techniques of mapping topography using either optical or radar images with or without reference to ground central points. Without ground control points, an integrated camera system can be designed. With ground control points, the position of the space station (camera station) can be precisely determined at any instant. Therefore, terrestrial topography can be precisely mapped either by conventional photogrammetric methods or by current digital technology of image correlation. For the mapping experiment, it is proposed to establish four ground points either in North America or Africa (including the Sahara desert). If this experiment should be successfully accomplished, it may also be applied to the defense charting systems.

  9. Isostatic Gravity Map of the Battle Mountain 30 x 60 Minute Quadrangle, North Central Nevada

    USGS Publications Warehouse

    Ponce, D.A.; Morin, R.L.

    2000-01-01

    Introduction Gravity investigations of the Battle Mountain 30 x 60 minute quadrangle were begun as part of an interagency effort by the U.S. Geological Survey (USGS) and the Bureau of Land Management to help characterize the geology, mineral resources, hydrology, and ecology of the Humboldt River Basin in north-central Nevada. The Battle Mountain quadrangle is located between 40?30' and 41?N. lat. and 116? and 117?W. long. This isostatic gravity map of the Battle Mountain quadrangle was prepared from data from about 1,180 gravity stations. Most of these data are publicly available on a CD-ROM of gravity data of Nevada (Ponce, 1997) and in a published report (Jewel and others, 1997). Data from about 780 gravity stations were collected by the U.S. Geological Survey since 1996; data from about 245 of these are unpublished (USGS, unpub. data, 1998). Data collected from the 400 gravity stations prior to 1996 are a subset of a gravity data compilation of the Winnemucca 1:250,000-scale quadrangle described in great detail by Wagini (1985) and Sikora (1991). This detailed information includes gravity meters used, dates of collection, sources, descriptions of base stations, plots of data, and a list of principal facts. A digital version of the entire data set for the Battle Mountain quadrangle is available on the World Wide Web at: http://wrgis.wr.usgs.gov/docs/gump/gump.html

  10. Comparison of survey and photogrammetry methods to position gravity data, Yucca Mountain, Nevada

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ponce, D.A.; Wu, S.S.C.; Spielman, J.B.

    1985-12-31

    Locations of gravity stations at Yucca Mountain, Nevada, were determined by a survey using an electronic distance-measuring device and by a photogram-metric method. The data from both methods were compared to determine if horizontal and vertical coordinates developed from photogrammetry are sufficently accurate to position gravity data at the site. The results show that elevations from the photogrammetric data have a mean difference of 0.57 +- 0.70 m when compared with those of the surveyed data. Comparison of the horizontal control shows that the two methods agreed to within 0.01 minute. At a latitude of 45{sup 0}, an error ofmore » 0.01 minute (18 m) corresponds to a gravity anomaly error of 0.015 mGal. Bouguer gravity anomalies are most sensitive to errors in elevation, thus elevation is the determining factor for use of photogrammetric or survey methods to position gravity data. Because gravity station positions are difficult to locate on aerial photographs, photogrammetric positions are not always exactly at the gravity station; therefore, large disagreements may appear when comparing electronic and photogrammetric measurements. A mean photogrammetric elevation error of 0.57 m corresponds to a gravity anomaly error of 0.11 mGal. Errors of 0.11 mGal are too large for high-precision or detailed gravity measurements but acceptable for regional work. 1 ref. 2 figs., 4 tabs.« less

  11. The absolute dynamic ocean topography (ADOT)

    NASA Astrophysics Data System (ADS)

    Bosch, Wolfgang; Savcenko, Roman

    The sea surface slopes relative to the geoid (an equipotential surface) basically carry the in-formation on the absolute velocity field of the surface circulation. Pure oceanographic models may remain unspecific with respect to the absolute level of the ocean topography. In contrast, the geodetic approach to estimate the ocean topography as difference between sea level and the geoid gives by definition an absolute dynamic ocean topography (ADOT). This approach requires, however, a consistent treatment of geoid and sea surface heights, the first being usually derived from a band limited spherical harmonic series of the Earth gravity field and the second observed with much higher spectral resolution by satellite altimetry. The present contribution shows a procedure for estimating the ADOT along the altimeter profiles, preserving as much sea surface height details as the consistency w.r.t. the geoid heights will allow. The consistent treatment at data gaps and the coast is particular demanding and solved by a filter correction. The ADOT profiles are inspected for their innocent properties towards the coast and compared to external estimates of the ocean topography or the velocity field of the surface circulation as derived, for example, by ARGO floats.

  12. Principal Facts of Gravity data in the Northern Willamette Valley and Vicinity, Northwestern Oregon and Southwestern Washington

    USGS Publications Warehouse

    Morin, Robert L.; Wheeler, Karen L.; McPhee, Darcy K.; Dinterman, Philip A.; Watt, Janet T.

    2007-01-01

    Gravity data were collected from 2004 through 2006 to assist in mapping subsurface geology in the northern Willamette Valley and vicinity, northwestern Oregon and southwestern Washington. Prior to this effort to improve the gravity data coverage in the study area, very little regional data were available. This report gives the principle facts for 2710 new gravity stations and 1446 preexisting gravity stations. Much of the study area is now covered with data of sufficient density to define basin boundaries and correlate with many of the larger fault systems. ,p> The study area lies between 44? 52.5 and 46? N latitude and between 122? 15 and 123? 37.5 W longitude. Although this is a continuing project and more gravity data is expected to be collected, this report is being published to show the progress of the data collection. The majority of these data are spaced at about 1.6 km (1 mile), but three closely spaced profiles were measured in the Portland area across several faults. To obtain a 1.6 km grid of data points would require about 5120 gravity stations. To date we have collected 2710 stations. Including the preexisting data points, the total number of stations is 4156, and complete regional coverage is about 80 percent at this time.

  13. Frequency characteristics and far-field effect of gravity perturbation before earthquake

    NASA Astrophysics Data System (ADS)

    Qiang, Jian-Ke; Lu, Kai; Zhang, Qian-Jiang; Man, Kai-Feng; Li, Jun-Ying; Mao, Xian-Cheng; Lai, Jian-Qing

    2017-03-01

    We used high-pass filtering and the Fourier transform to analyze tidal gravity data prior to five earthquakes from four superconducting gravity stations around the world. A stable gravitational perturbation signal is received within a few days before the earthquakes. The gravitational perturbation signal before the Wenchuan earthquake on May 12, 2008 has main frequency of 0.1-0.3 Hz, and the other four have frequency bands of 0.12-0.17 Hz and 0.06-0.085 Hz. For earthquakes in continental and oceanic plate fault zones, gravity anomalies often appear on the superconducting gravimeters away from the epicenter, whereas the stations near the epicenter record small or no anomalies. The results suggest that this kind of gravitational perturbation signals correlate with earthquake occurrence, making them potentially useful earthquake predictors. The far-field effect of the gravitational perturbation signals may reveal the interaction mechanisms of the Earth's tectonic plates. However, owing to the uneven distribution of gravity tide stations, the results need to be further confirmed in the future.

  14. Space station control moment gyro control

    NASA Technical Reports Server (NTRS)

    Bordano, Aldo

    1987-01-01

    The potential large center-of-pressure to center-of-gravity offset of the space station makes the short term, within an orbit, variations in density of primary importance. The large range of uncertainty in the prediction of solar activity will penalize the design, developments, and operation of the space station.

  15. Terrestrial gravity instrumentation in the 20th Century: A brief review

    NASA Technical Reports Server (NTRS)

    Valliant, H. D.

    1989-01-01

    At the turn of the century, only pendulum apparatuses and torsion balances were available for general exploration work. Both of these early techniques were cumbersome and time-consuming. It was no wonder that the development of the gravity meter was welcomed with a universal sigh of relief. By 1935 potential field measurements with gravity meters supplanted gradient measurements with torsion balances. Potential field measurements are generally characterized by three types: absolute - measurements are made in fundamental units, traceable to national standards of length and time at each observation site; relative with absolute scale - differences in gravity are measured in fundamental units traceable to national standards of length and time; and relative - differences in gravity are measured with arbitrary scale. Improvements in the design of gravity meters since their introduction has led to a significant reduction in size and greatly increased precision. As the precision increased, applications expanded to include the measurement of crustal motion, the search for non-Newtonian forces, archeology, and civil engineering. Apart from enhancements to the astatic gravity meter, few developments in hardware were achieved. One of these was the vibrating string gravity meter which was developed in the 1950s and was employed briefly for marine and borehole applications. Another is the cryogenic gravity meter which utilizes the stability of superconducting current to achieve a relative instrument with extremely low drift suitable for tidal and secular gravity measurements. An advance in performing measurements from a moving platform was achieved with the development of the straight-line gravity meter. The latter part of the century also saw the rebirth of gradient measurements which offers advantages for observations from a moving platform. Definitive testing of the Bell gradiometer was recently reported.

  16. TEM and Gravity Data for Roosevelt Hot Springs, Utah FORGE Site

    DOE Data Explorer

    Hardwick, Christian; Nash, Greg

    2018-02-05

    This submission includes a gravity data in text format and as a GIS point shapefile and transient electromagnetic (TEM) raw data. Each text file additionally contains location data (UTM Zone 12, NAD83) and elevation (meters) data for that station. The gravity data shapefile was in part downloaded from PACES, University of Texas at El Paso, http://gis.utep.edu/subpages/GMData.html, and in part collected by the Utah Geological Survey (UGS) as part of the DOE GTO supported Utah FORGE geothermal energy project near Milford, Utah. The PACES data were examined and scrubbed to eliminate any questionable data. A 2.67 g/cm^3 reduction density was used for the Bouguer correction. The attribute table column headers for the gravity data shapefile are explained below. There is also metadata attached to the GIS shapefile. name: the individual gravity station name. HAE: height above ellipsoid [meter] NGVD29: vertical datum for geoid [meter] obs: observed gravity ERRG: gravity measurement error [mGal] IZTC: inner zone terrain correction [mGal] OZTC: outer zone terrain correction [mGal] Gfa: free air gravity gSBGA: Bouguer horizontal slab sCBGA: Complete Bouguer anomaly

  17. Mechanism of secular increasing of mean gravity in Northern hemisphere and secular decreasing of mean gravity in Southern hemisphere

    NASA Astrophysics Data System (ADS)

    Barkin, Yu. V.; Ferrandiz, J. M.

    2009-04-01

    regions (for example, in subduction zones, a hilly terrain, a zone of volcanism etc.) at times is more brightly shown. Therefore the steadfast attention should be paid to local factors of changes of a gravity. In result the phenomenon of inversion changes of a gravity in northern and southern hemispheres has been predicted: mean value of a gravity in northern hemisphere accrues with velocity 1.36 micro gals in year (mGal), and in southern decreases with the same velocity. Secular variations of a gravity depend from latitude and on equator (within the framework of considered model) change a sign: dg=2.72tsinф micro gals in year (mGal), where ф is a latitude of a place of observations, t is the time in years (Barkin, 2005). The data of gravimetric measurements at the European stations: Metsahovi, Potsdam, Moha, Vienna, Wettzell, Strastburg, Medicina etc., in Asia and Australia: Eshashi, Canberra etc., in Northern and South America: Bolder (Colorado), Patagonia (Argentina) etc., and also in Antarctic Region (station Syowa), will well be coordinated to the theoretical values of secular variations of a gravity predicted earlier at the specified stations. Gravity trends are studied and evaluated after removal effects of tides, local pressure and polar motion. The secular gravity variation at Potsdam is evaluated in 2.1 mGal/yr. During 1976-1986 the similar tendency - gravity trend with velocity 2.6 mGal/yr (absolute measurements) here have been observed. The similar tendency has been determined on measurements on superconducting gravimeters during 1993-1997: 2.3-2.5 mGal/yr (Neumeyer and Dittfeled, 1997). For more extensive period of observation (Neumayer, 2002) the similar result for gravity trend has been obtained. Observable annual variations of a gravity are characterized by amplitude about 3 mGal (on our model it is 3.5 mGal). Observations at Syowa station have been confirmed the developed model. Here it was expected negative gravity trend - decreasing of gravity with

  18. On the Retrieval of Geocenter Motion from Gravity Data

    NASA Astrophysics Data System (ADS)

    Rosat, S.; Mémin, A.; Boy, J. P.; Rogister, Y. J. G.

    2017-12-01

    The center of mass of the whole Earth, the so-called geocenter, is moving with respect to the Center of Mass of the solid Earth because of the loading exerted by the Earth's fluid layers on the solid crust. Space geodetic techniques tying satellites and ground stations (e.g. GNSS, SLR and DORIS) have been widely employed to estimate the geocenter motion. Harmonic degree-1 variations of the gravity field are associated to the geocenter displacement. We show that ground records of time-varying gravity from Superconducting Gravimeters (SGs) can be used to constrain the geocenter motion. Two major difficulties have to be tackled: (1) the sensitivity of surface gravimetric measurements to local mass changes, and in particular hydrological and atmospheric variabilities; (2) the spatial aliasing (spectral leakage) of spherical harmonic degrees higher than 1 induced by the under-sampling of station distribution. The largest gravity variations can be removed from the SG data by subtracting solid and oceanic tides as well as atmospheric and hydrologic effects using global models. However some hydrological signal may still remain. Since surface water content is well-modelled using GRACE observations, we investigate how the spatial aliasing in SG data can be reduced by employing GRACE solutions when retrieving geocenter motion. We show synthetic simulations using complete surface loading models together with GRACE solutions computed at SG stations. In order to retrieve the degree-one gravity variations that are associated with the geocenter motion, we use a multi-station stacking method that performs better than a classical spherical harmonic stacking when the station distribution is inhomogeneous. We also test the influence of the network configuration on the estimate of the geocenter motion. An inversion using SG and GRACE observations is finally presented and the results are compared with previous geocenter estimates.

  19. A Space Station tethered orbital refueling facility

    NASA Technical Reports Server (NTRS)

    Fester, D. A.; Rudolph, L. K.; Kiefel, E. R.

    1985-01-01

    A planned function of the Space Station is to refurbish and refuel an advanced space-based LO2/LH2 orbit transfer vehicle. An alternative to propellant storage at the station is to use a remote facility tied to the station with a long tether. Preliminary design of such a facility is described with emphasis on fluid transfer and storage requirements. Using tether lengths of at least 300 ft, gravity gradient forces will dominate surface tension in such a system. Although gravity driven transfer is difficult because of line pressure drops, fluid settling over the tank outlet greatly alleviates acquisition concerns and will facilitate vented tank fills. The major concern with a tethered orbital refueling facility is its considerable operational complexity including transport of the OTV to and from the facility.

  20. The European Comparison of Absolute Gravimeters 2011 (ECAG-2011) in Walferdange, Luxembourg: results and recommendations

    NASA Astrophysics Data System (ADS)

    Francis, Olivier; Baumann, Henri; Volarik, Tomas; Rothleitner, Christian; Klein, Gilbert; Seil, Marc; Dando, Nicolas; Tracey, Ray; Ullrich, Christian; Castelein, Stefaan; Hua, Hu; Kang, Wu; Chongyang, Shen; Songbo, Xuan; Hongbo, Tan; Zhengyuan, Li; Pálinkás, Vojtech; Kostelecký, Jakub; Mäkinen, Jaakko; Näränen, Jyri; Merlet, Sébastien; Farah, Tristan; Guerlin, Christine; Pereira Dos Santos, Franck; Le Moigne, Nicolas; Champollion, Cédric; Deville, Sabrina; Timmen, Ludger; Falk, Reinhard; Wilmes, Herbert; Iacovone, Domenico; Baccaro, Francesco; Germak, Alessandro; Biolcati, Emanuele; Krynski, Jan; Sekowski, Marcin; Olszak, Tomasz; Pachuta, Andrzej; Agren, Jonas; Engfeldt, Andreas; Reudink, René; Inacio, Pedro; McLaughlin, Daniel; Shannon, Geoff; Eckl, Marc; Wilkins, Tim; van Westrum, Derek; Billson, Ryan

    2013-06-01

    We present the results of the third European Comparison of Absolute Gravimeters held in Walferdange, Grand Duchy of Luxembourg, in November 2011. Twenty-two gravimeters from both metrological and non-metrological institutes are compared. For the first time, corrections for the laser beam diffraction and the self-attraction of the gravimeters are implemented. The gravity observations are also corrected for geophysical gravity changes that occurred during the comparison using the observations of a superconducting gravimeter. We show that these corrections improve the degree of equivalence between the gravimeters. We present the results for two different combinations of data. In the first one, we use only the observations from the metrological institutes. In the second solution, we include all the data from both metrological and non-metrological institutes. Those solutions are then compared with the official result of the comparison published previously and based on the observations of the metrological institutes and the gravity differences at the different sites as measured by non-metrological institutes. Overall, the absolute gravity meters agree with one another with a standard deviation of 3.1 µGal. Finally, the results of this comparison are linked to previous ones. We conclude with some important recommendations for future comparisons.

  1. Results of the first North American comparison of absolute gravimeters, NACAG-2010

    USGS Publications Warehouse

    Schmerge, David; Francis, Olvier; Henton, J.; Ingles, D.; Jones, D.; Kennedy, Jeffrey R.; Krauterbluth, K.; Liard, J.; Newell, D.; Sands, R.; Schiel, J.; Silliker, J.; van Westrum, D.

    2012-01-01

    The first North American Comparison of absolute gravimeters (NACAG-2010) was hosted by the National Oceanic and Atmospheric Administration at its newly renovated Table Mountain Geophysical Observatory (TMGO) north of Boulder, Colorado, in October 2010. NACAG-2010 and the renovation of TMGO are part of NGS’s GRAV-D project (Gravity for the Redefinition of the American Vertical Datum). Nine absolute gravimeters from three countries participated in the comparison. Before the comparison, the gravimeter operators agreed to a protocol describing the strategy to measure, calculate, and present the results. Nine sites were used to measure the free-fall acceleration of g. Each gravimeter measured the value of g at a subset of three of the sites, for a total set of 27 g-values for the comparison. The absolute gravimeters agree with one another with a standard deviation of 1.6 µGal (1 Gal = 1 cm s-2). The minimum and maximum offsets are -2.8 and 2.7 µGal. This is an excellent agreement and can be attributed to multiple factors, including gravimeters that were in good working order, good operators, a quiet observatory, and a short duration time for the experiment. These results can be used to standardize gravity surveys internationally.

  2. An evaluation of gravity waves and gravity wave sources in the Southern Hemisphere in a 7 km global climate simulation.

    PubMed

    Holt, L A; Alexander, M J; Coy, L; Liu, C; Molod, A; Putman, W; Pawson, S

    2017-07-01

    In this study, gravity waves (GWs) in the high-resolution GEOS-5 Nature Run are first evaluated with respect to satellite and other model results. Southern Hemisphere winter sources of non-orographic GWs in the model are then investigated by linking measures of tropospheric non-orographic gravity wave generation tied to precipitation and frontogenesis with absolute gravity wave momentum flux in the lower stratosphere. Finally, non-orographic GW momentum flux is compared to orographic gravity wave momentum flux and compared to previous estimates. The results show that the global patterns in GW amplitude, horizontal wavelength, and propagation direction are realistic compared to observations. However, as in other global models, the amplitudes are weaker and horizontal wavelengths longer than observed. The global patterns in absolute GW momentum flux also agree well with previous model and observational estimates. The evaluation of model non-orographic GW sources in the Southern Hemisphere winter shows that strong intermittent precipitation (greater than 10 mm h -1 ) is associated with GW momentum flux over the South Pacific, whereas frontogenesis and less intermittent, lower precipitation rates (less than 10 mm h -1 ) are associated with GW momentum flux near 60°S. In the model, orographic GWs contribute almost exclusively to a peak in zonal mean momentum flux between 70 and 75°S, while non-orographic waves dominate at 60°S, and non-orographic GWs contribute a third to a peak in zonal mean momentum flux between 25 and 30°S.

  3. Gravity signatures of terrane accretion

    NASA Astrophysics Data System (ADS)

    Franco, Heather; Abbott, Dallas

    1999-01-01

    In modern collisional environments, accreted terranes are bracketed by forearc gravity lows, a gravitational feature which results from the abandonment of the original trench and the initiation of a new trench seaward of the accreted terrane. The size and shape of the gravity low depends on the type of accreted feature and the strength of the formerly subducting plate. Along the Central American trench, the accretion of Gorgona Island caused a seaward trench jump of 48 to 66 km. The relict trench axes show up as gravity lows behind the trench with minimum values of -78 mgal (N of Gorgona) and -49 mgal (S of Gorgona) respectively. These forearc gravity lows have little or no topographic expression. The active trench immediately seaward of these forearc gravity lows has minimum gravity values of -59 mgal (N of Gorgona) and -58 mgal (S of Gorgona), respectively. In the north, the active trench has a less pronounced gravity low than the sediment covered forearc. In the Mariana arc, two Cretaceous seamounts have been accreted to the Eocene arc. The northern seamount is most likely a large block, the southern seamount may be a thrust slice. These more recent accretion events have produced modest forearc topographic and gravity lows in comparison with the topographic and gravity lows within the active trench. However, the minimum values of the Mariana forearc gravity lows are modest only by comparison to the Mariana Trench (-216 mgal); their absolute values are more negative than at Gorgona Island (-145 to -146 mgal). We speculate that the forearc gravity lows and seaward trench jumps near Gorgona Island were produced by the accretion of a hotspot island from a strong plate. The Mariana gravity lows and seaward trench jumps (or thrust slices) were the result of breaking a relatively weak plate close to the seamount edifice. These gravity lows resulting from accretion events should be preserved in older accreted terranes.

  4. A computer system for the storage and retrieval of gravity data, Kingdom of Saudi Arabia

    USGS Publications Warehouse

    Godson, Richard H.; Andreasen, Gordon H.

    1974-01-01

    A computer system has been developed for the systematic storage and retrieval of gravity data. All pertinent facts relating to gravity station measurements and computed Bouguer values may be retrieved either by project name or by geographical coordinates. Features of the system include visual display in the form of printer listings of gravity data and printer plots of station locations. The retrieved data format interfaces with the format of GEOPAC, a system of computer programs designed for the analysis of geophysical data.

  5. Levels at gaging stations

    USGS Publications Warehouse

    Kenney, Terry A.

    2010-01-01

    Operational procedures at U.S. Geological Survey gaging stations include periodic leveling checks to ensure that gages are accurately set to the established gage datum. Differential leveling techniques are used to determine elevations for reference marks, reference points, all gages, and the water surface. The techniques presented in this manual provide guidance on instruments and methods that ensure gaging-station levels are run to both a high precision and accuracy. Levels are run at gaging stations whenever differences in gage readings are unresolved, stations may have been damaged, or according to a pre-determined frequency. Engineer's levels, both optical levels and electronic digital levels, are commonly used for gaging-station levels. Collimation tests should be run at least once a week for any week that levels are run, and the absolute value of the collimation error cannot exceed 0.003 foot/100 feet (ft). An acceptable set of gaging-station levels consists of a minimum of two foresights, each from a different instrument height, taken on at least two independent reference marks, all reference points, all gages, and the water surface. The initial instrument height is determined from another independent reference mark, known as the origin, or base reference mark. The absolute value of the closure error of a leveling circuit must be less than or equal to ft, where n is the total number of instrument setups, and may not exceed |0.015| ft regardless of the number of instrument setups. Closure error for a leveling circuit is distributed by instrument setup and adjusted elevations are determined. Side shots in a level circuit are assessed by examining the differences between the adjusted first and second elevations for each objective point in the circuit. The absolute value of these differences must be less than or equal to 0.005 ft. Final elevations for objective points are determined by averaging the valid adjusted first and second elevations. If final elevations

  6. Airborne Sea-Surface Topography in an Absolute Reference Frame

    NASA Astrophysics Data System (ADS)

    Brozena, J. M.; Childers, V. A.; Jacobs, G.; Blaha, J.

    2003-12-01

    Highly dynamic coastal ocean processes occur at temporal and spatial scales that cannot be captured by the present generation of satellite altimeters. Space-borne gravity missions such as GRACE also provide time-varying gravity and a geoidal msl reference surface at resolution that is too coarse for many coastal applications. The Naval Research Laboratory and the Naval Oceanographic Office have been testing the application of airborne measurement techniques, gravity and altimetry, to determine sea-surface height and height anomaly at the short scales required for littoral regions. We have developed a precise local gravimetric geoid over a test region in the northern Gulf of Mexico from historical gravity data and recent airborne gravity surveys. The local geoid provides a msl reference surface with a resolution of about 10-15 km and provides a means to connect airborne, satellite and tide-gage observations in an absolute (WGS-84) framework. A series of altimetry reflights over the region with time scales of 1 day to 1 year reveal a highly dynamic environment with coherent and rapidly varying sea-surface height anomalies. AXBT data collected at the same time show apparent correlation with wave-like temperature anomalies propagating up the continental slope of the Desoto Canyon. We present animations of the temporal evolution of the surface topography and water column temperature structure down to the 800 m depth of the AXBT sensors.

  7. Modular Extended-Stay HyperGravity Facility Design Concept: An Artificial-Gravity Space-Settlement Ground Analogue

    NASA Technical Reports Server (NTRS)

    Dorais, Gregory A.

    2015-01-01

    This document defines the design concept for a ground-based, extended-stay hypergravity facility as a precursor for space-based artificial-gravity facilities that extend the permanent presence of both human and non-human life beyond Earth in artificial-gravity settlements. Since the Earth's current human population is stressing the environment and the resources off-Earth are relatively unlimited, by as soon as 2040 more than one thousand people could be living in Earthorbiting artificial-gravity habitats. Eventually, the majority of humanity may live in artificialgravity habitats throughout this solar system as well as others, but little is known about the longterm (multi-generational) effects of artificial-gravity habitats on people, animals, and plants. In order to extend life permanently beyond Earth, it would be useful to create an orbiting space facility that generates 1g as well as other gravity levels to rigorously address the numerous challenges of such an endeavor. Before doing so, developing a ground-based artificial-gravity facility is a reasonable next step. Just as the International Space Station is a microgravity research facility, at a small fraction of the cost and risk a ground-based artificial-gravity facility can begin to address a wide-variety of the artificial-gravity life-science questions and engineering challenges requiring long-term research to enable people, animals, and plants to live off-Earth indefinitely.

  8. Major results of gravity and magnetic studies at Yucca Mountain, Nevada

    USGS Publications Warehouse

    Oliver, H.W.; Ponce, D.A.; Sikora, R.F.; ,

    1991-01-01

    About 4,000 gravity stations have been obtained at Yucca Mountain and vicinity since the beginning of radioactive-waste studies there in 1978. These data have been integrated with data from about 29,000 stations previously obtained in the surrounding region to produce a series of Bouguer and isostatic-residual-gravity maps of the Nevada Test Site and southeastern Nevada. Yucca Mountain is characterized by a WNW-dipping gravity gradient whereby residual values of -10 mGal along the east edge of Yucca Mountain decrease to about -38 mGal over Crater Flat. Using these gravity data, two-dimensional modeling predicted the depth to pre-Cenozoic rocks near the proposed repository to be about 1,220??150 m, an estimate that was subsequently confirmed by drilling to be 1,244 m. Three-dimensional modeling of the gravity low over Crater Flat indicates the thickness of Cenozoic volcanic rocks and alluvial cover to be about 3,000 m. Gravity interpretations also identified the Silent Canyon caldera before geologic mapping of Pahute Mesa and provided an estimate of the thickness of the volcanic section there of nearly 5 km.

  9. Variable gravity research facility

    NASA Technical Reports Server (NTRS)

    Allan, Sean; Ancheta, Stan; Beine, Donna; Cink, Brian; Eagon, Mark; Eckstein, Brett; Luhman, Dan; Mccowan, Daniel; Nations, James; Nordtvedt, Todd

    1988-01-01

    Spin and despin requirements; sequence of activities required to assemble the Variable Gravity Research Facility (VGRF); power systems technology; life support; thermal control systems; emergencies; communication systems; space station applications; experimental activities; computer modeling and simulation of tether vibration; cost analysis; configuration of the crew compartments; and tether lengths and rotation speeds are discussed.

  10. Gravity and crustal movements: The canadian experience

    NASA Astrophysics Data System (ADS)

    Tanner, J. G.; Lambert, A.

    1987-07-01

    Repeated high precision gravity measurement have already played an important role in the detection of crustal deformation in Canada and elsewhere, but even more useful results can be expected through more widespread use of gravity in combination with other techniques. The crucial element in the process is the development of a good physical model on which the experiment can be based. Otherwise, considerable time and effort can be spent on determining the most appropriate field strategy. New technical developments on the horizon appear to offer enhanced opportunities for gravity studies of crustal processes. The coming availability of the Global Positioning System and transportable absolute gravimeters will open up the possibility of regional studies (i.e., areas of the order of 100 km or perhaps greater) of crustal movements at reasonable cost. Within Africa the development of an African Gravity Standardization Net will be a major first step in any program to provide a better understanding of the neo-tectonic framework of this vast continent.

  11. 2006 Compilation of Alaska Gravity Data and Historical Reports

    USGS Publications Warehouse

    Saltus, Richard W.; Brown, Philip J.; Morin, Robert L.; Hill, Patricia L.

    2008-01-01

    Gravity anomalies provide fundamental geophysical information about Earth structure and dynamics. To increase geologic and geodynamic understanding of Alaska, the U.S. Geological Survey (USGS) has collected and processed Alaska gravity data for the past 50 years. This report introduces and describes an integrated, State-wide gravity database and provides accompanying gravity calculation tools to assist in its application. Additional information includes gravity base station descriptions and digital scans of historical USGS reports. The gravity calculation tools enable the user to reduce new gravity data in a consistent manner for combination with the existing database. This database has sufficient resolution to define the regional gravity anomalies of Alaska. Interpretation of regional gravity anomalies in parts of the State are hampered by the lack of local isostatic compensation in both southern and northern Alaska. However, when filtered appropriately, the Alaska gravity data show regional features having geologic significance. These features include gravity lows caused by low-density rocks of Cenozoic basins, flysch belts, and felsic intrusions, as well as many gravity highs associated with high-density mafic and ultramafic complexes.

  12. The oscillation model of hydrothermal dynamics beneath Aso volcano, southwest Japan after small eruption on May 2011: A new understanding model using repeated absolute and relative gravity measurement

    NASA Astrophysics Data System (ADS)

    Sofyan, Yayan; Nishijima, Jun; Fujimitsu, Yasuhiro; Yoshikawa, Shin; Kagiyama, Tsuneomi; Ohkura, Takahiro

    2016-01-01

    At the end of 2010, the seismic activity in Aso volcano intensely increased and water level in the Nakadake crater decreased until early in 2011, then was followed by a small eruption in May 2011. After the eruption and heavy rain, the volcanic activity subsided to calm period, crater bottom was refilled with water, and water level increased in the Nakadake crater. The next tremor reappeared in 2014 and tracked to eruption in November 2014. This eruptive pattern and water level variation in the crater repeatedly appeared on the surface, and it should be related to the hydrothermal dynamics beneath Aso volcano. We initiated the gravity measurements in relation to hydrothermal dynamics in the subsurface of Aso volcano using Scintrex CG-5 (549) and LaCoste Romberg type G-1016 relative gravimeter at 28 benchmarks in April 2011, one month before the eruption. The repeated gravity measurements continue to monitor Aso volcano with a series of the measurement after the eruption in every three months to a half year. We analyze the gravity variation from 2011 to 2014 between the time of the phreatic and strombolian eruption. The measurements covered the area more than 60 km2 in the west side of Aso caldera. A new gravity network was also installed in May 2010 at seven benchmarks using A10-017 absolute gravimeter, which re-occupied in October 2010, June 2011 and two benchmarks in June 2014. As a result, the gravity changes distinguish hydrothermal dynamic in the subsurface, which has a direct correlation to water level fluctuation in the crater, after the first eruption and before the second discharge. The monitoring data notice large gravity changes between the surveys at benchmarks around Nakadake crater and Kusasenri area. The simple 3D inversion models of the 4-D gravity data deduce the density contrast distribution beneath Aso volcano. The inversion and mass change result generate the oscillation typical as a new understanding model. The variation of the mass shows a

  13. Gravity anomaly detection: Apollo/Soyuz

    NASA Technical Reports Server (NTRS)

    Vonbun, F. O.; Kahn, W. D.; Bryan, J. W.; Schmid, P. E.; Wells, W. T.; Conrad, D. T.

    1976-01-01

    The Goddard Apollo-Soyuz Geodynamics Experiment is described. It was performed to demonstrate the feasibility of tracking and recovering high frequency components of the earth's gravity field by utilizing a synchronous orbiting tracking station such as ATS-6. Gravity anomalies of 5 MGLS or larger having wavelengths of 300 to 1000 kilometers on the earth's surface are important for geologic studies of the upper layers of the earth's crust. Short wavelength Earth's gravity anomalies were detected from space. Two prime areas of data collection were selected for the experiment: (1) the center of the African continent and (2) the Indian Ocean Depression centered at 5% north latitude and 75% east longitude. Preliminary results show that the detectability objective of the experiment was met in both areas as well as at several additional anomalous areas around the globe. Gravity anomalies of the Karakoram and Himalayan mountain ranges, ocean trenches, as well as the Diamantina Depth, can be seen. Maps outlining the anomalies discovered are shown.

  14. Principal facts for gravity stations in the vicinity of San Bernardino, Southern California

    USGS Publications Warehouse

    Anderson, Megan L.; Roberts, Carter W.; Jachens, Robert C.

    2000-01-01

    New gravity measurements in the vicinity of San Bernardino, California were collected to help define the characteristics of the Rialto-Colton fault. The data were processed using standard reduction formulas and parameters. Rock properties such as lithology, magnetic susceptibility and density also were measured at several locations. Rock property measurements will be helpful for future modeling and density inversion calculations from the gravity data. On both the Bouguer and isostatic gravity maps, a prominent, 13-km long (8 mi), approximately 1-km (0.62 mi) wide gradient with an amplitude of 7 mGal, down to the northeast, is interpreted as the gravity expression of the Rialto-Colton fault. The gravity gradient strikes in a northwest direction and runs from the San Jacinto fault zone at its south end to San Sevine Canyon at the foot of the San Gabriel mountains at its north end. The Rialto-Colton fault has experienced both right-lateral strike-slip and normal fault motion that has offset basement rocks; therefore it is interpreted as a major, through-going fault.

  15. New Data Bases and Standards for Gravity Anomalies

    NASA Astrophysics Data System (ADS)

    Keller, G. R.; Hildenbrand, T. G.; Webring, M. W.; Hinze, W. J.; Ravat, D.; Li, X.

    2008-12-01

    Ever since the use of high-precision gravimeters emerged in the 1950's, gravity surveys have been an important tool for geologic studies. Recent developments that make geologically useful measurements from airborne and satellite platforms, the ready availability of the Global Positioning System that provides precise vertical and horizontal control, improved global data bases, and the increased availability of processing and modeling software have accelerated the use of the gravity method. As a result, efforts are being made to improve the gravity databases publicly available to the geoscience community by expanding their holdings and increasing the accuracy and precision of the data in them. Specifically the North American Gravity Database as well as the individual databases of Canada, Mexico, and the United States are being revised using new formats and standards to improve their coverage, standardization, and accuracy. An important part of this effort is revision of procedures and standards for calculating gravity anomalies taking into account the enhanced computational power available, modern satellite-based positioning technology, improved terrain databases, and increased interest in more accurately defining the different components of gravity anomalies. The most striking revision is the use of one single internationally accepted reference ellipsoid for the horizontal and vertical datums of gravity stations as well as for the computation of the calculated value of theoretical gravity. The new standards hardly impact the interpretation of local anomalies, but do improve regional anomalies in that long wavelength artifacts are removed. Most importantly, such new standards can be consistently applied to gravity database compilations of nations, continents, and even the entire world. Although many types of gravity anomalies have been described, they fall into three main classes. The primary class incorporates planetary effects, which are analytically prescribed, to

  16. New standards for reducing gravity data: The North American gravity database

    USGS Publications Warehouse

    Hinze, W. J.; Aiken, C.; Brozena, J.; Coakley, B.; Dater, D.; Flanagan, G.; Forsberg, R.; Hildenbrand, T.; Keller, Gordon R.; Kellogg, J.; Kucks, R.; Li, X.; Mainville, A.; Morin, R.; Pilkington, M.; Plouff, D.; Ravat, D.; Roman, D.; Urrutia-Fucugauchi, J.; Veronneau, M.; Webring, M.; Winester, D.

    2005-01-01

    The North American gravity database as well as databases from Canada, Mexico, and the United States are being revised to improve their coverage, versatility, and accuracy. An important part of this effort is revising procedures for calculating gravity anomalies, taking into account our enhanced computational power, improved terrain databases and datums, and increased interest in more accurately defining long-wavelength anomaly components. Users of the databases may note minor differences between previous and revised database values as a result of these procedures. Generally, the differences do not impact the interpretation of local anomalies but do improve regional anomaly studies. The most striking revision is the use of the internationally accepted terrestrial ellipsoid for the height datum of gravity stations rather than the conventionally used geoid or sea level. Principal facts of gravity observations and anomalies based on both revised and previous procedures together with germane metadata will be available on an interactive Web-based data system as well as from national agencies and data centers. The use of the revised procedures is encouraged for gravity data reduction because of the widespread use of the global positioning system in gravity fieldwork and the need for increased accuracy and precision of anomalies and consistency with North American and national databases. Anomalies based on the revised standards should be preceded by the adjective "ellipsoidal" to differentiate anomalies calculated using heights with respect to the ellipsoid from those based on conventional elevations referenced to the geoid. ?? 2005 Society of Exploration Geophysicists. All rights reserved.

  17. Space Station truss structures and construction considerations

    NASA Technical Reports Server (NTRS)

    Mikulas, M. M., Jr.; Croomes, S. D.; Schneider, W.; Bush, H. G.; Nagy, K.; Pelischek, T.; Lake, M. S.; Wesselski, C.

    1985-01-01

    Although a specific configuration has not been selected for the Space Station, a gravity gradient stabilized station as a basis upon which to compare various structural and construction concepts is considered. The Space Station primary truss support structure is described in detail. Three approaches (see sketch A) which are believed to be representative of the major techniques for constructing large structures in space are also described in detail so that salient differences can be highlighted.

  18. Flexural-gravity Wave Attenuation in a Thick Ice Shelf

    NASA Astrophysics Data System (ADS)

    Stephen, R. A.; Bromirski, P. D.; Gerstoft, P.; Chen, Z.; Wiens, D.; Aster, R. C.; Nyblade, A.

    2016-12-01

    A thirty-four station broadband seismic array was deployed on the Ross Ice Shelf, Antarctica from November 2014 to November 2017. Analyses indicate that phase speeds of infra-gravity wave and tsunami excitation in the 0.003 to 0.02 Hz band are 70 m/s, corresponding to the low frequency limit of flexural-gravity waves. Median spectral amplitudes in this band decay exponentially with distance from the shelf edge in a manner consistent with intrinsic attenuation. Seismic Q is typically 7-9, with an RMS amplitude decay of 0.04-0.05dB/km and an e-folding distance of 175-220 km. Amplitudes do not appear to drop crossing crevasse fields. Vertical and horizontal acceleration levels at stations on the floating ice shelf are 50 dB higher than those on grounded ice. Horizontal accelerations are about 15 dB higher than vertical accelerations. Median spectral levels at 0.003 Hz are within 6 dB for stations from 2 to 430 km from the shelf edge. In contrast, the levels drop by 90 dB at 0.02 Hz. Ocean gravity wave excitation has been proposed as a mechanism that can weaken ice shelves and potentially trigger disintegration events. These measurements indicate that the propensity for shelf weakening and disintegration decays exponentially with distance from the ice front for gravity waves in the 0.003 to 0.02Hz band.

  19. Microgravity methods for characterization of groundwater-storage changes and aquifer properties in the karstic Madison aquifer in the Black Hills of South Dakota, 2009-12

    USGS Publications Warehouse

    Koth, Karl R.; Long, Andrew J.

    2012-01-01

    A study of groundwater storage in the karstic Madison aquifer in the Black Hills of South Dakota using microgravity methods was conducted by the U.S. Geological Survey in cooperation with West Dakota Water Development District, South Dakota Department of Environment and Natural Resources, and Lawrence County. Microgravity measurements from 2009 to 2012 were used to investigate groundwater-storage changes and effective porosity in unconfined areas of the Madison aquifer. Time-lapse microgravity surveys that use portable high-sensitivity absolute and relative gravimeters indicated temporal-gravity changes as a result of changing groundwater mass. These extremely precise measurements of gravity required characterization and removal of internal instrumental and external environmental effects on gravity from the raw data. The corrected data allowed groundwater-storage volume to be quantified with an accuracy of about plus or minus 0.5 foot of water per unit area of aquifer. Quantification of groundwater-storage change, coupled with water-level data from observation wells located near the focus areas, also was used to calculate the effective porosity at specific altitudes directly beneath gravity stations. Gravity stations were established on bedrock outcrops in three separate focus areas for this study. The first area, the Spring Canyon focus area, is located to the south of Rapid City with one gravity station on the rim of Spring Canyon near the area where Spring Creek sinks into the Madison aquifer. The second area, the Doty focus area, is located on outcrops of the Madison Limestone and Minnelusa Formation to the northwest of Rapid City, and consists of nine gravity stations. The third area, the Limestone Plateau focus area, consists of a single gravity station in the northwestern Black Hills located on an outcrop of the Madison Limestone. An absolute-gravity station, used to tie relative-gravity survey data together, was established on a relatively impermeable

  20. Dissolved oxygen in gravity sewers--measurement and simulation.

    PubMed

    Gudjonsson, G; Vollertsen, J; Hvitved-Jacobsen, T

    2002-01-01

    Dissolved oxygen (DO) concentrations were during 2 months continuously measured in an intercepting sewer. Measurements were made upstream and downstream in a 3.6 km gravity sewer. DO showed significant diurnal variations mainly caused by changes in the organic matter composition of the wastewater. At low temperatures the gravity sewer was strictly aerobic. However, towards the end of the measuring campaign, DO concentrations decreased as temperature increased and the sewer became anaerobic part of the day. A conceptual model that takes into account bulk water and biofilm DO uptake as well as reaeration was used to simulate the DO measured. Using measurements from the upstream station as input, the model was calibrated to yield good validation results of the DO at the downstream station.

  1. Atom Interferometer Technologies in Space for Gravity Mapping and Gravity Science

    NASA Astrophysics Data System (ADS)

    Williams, Jason; Chiow, Sheng-Wey; Kellogg, James; Kohel, James; Yu, Nan

    2015-05-01

    Atom interferometers utilize the wave-nature of atomic gases for precision measurements of inertial forces, with potential applications ranging from gravity mapping for planetary science to unprecedented tests of fundamental physics with quantum gases. The high stability and sensitivity intrinsic to these devices already place them among the best terrestrial sensors available for measurements of gravitational accelerations, rotations, and gravity gradients, with the promise of several orders of magnitude improvement in their detection sensitivity in microgravity. Consequently, multiple precision atom-interferometer-based projects are under development at the Jet Propulsion Laboratory, including a dual-atomic-species interferometer that is to be integrated into the Cold Atom Laboratory onboard the International Space Station and a highly stable gravity gradiometer in a transportable design relevant for earth science measurements. We will present JPL's activities in the use of precision atom interferometry for gravity mapping and gravitational wave detection in space. Our recent progresses bringing the transportable JPL atom interferometer instrument to be competitive with the state of the art and simulations of the expected capabilities of a proposed flight project will also be discussed. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

  2. Explanation of random experiment sheduling and its application to space station analysis

    NASA Technical Reports Server (NTRS)

    Moore, J. E.

    1970-01-01

    The capability of the McDonnell-Douglas Phase B space station concept to complete the Blue Book Experiment program is analyzed and the Random experiment program with Resource Impact (REPRI) which was used to generate the data is described. The results indicate that station manpower and electrical power are the two resources which will constrain the amount of the Blue Book program that the station can complete. The station experiment program and its resource requirements are sensitive to levels of manpower and electrical power 13.5 men and 11 kilowatts. Continuous artificial gravity experiments have much less impact on the experiment program than experiments using separate artificial gravity periods. Station storage volume presently allocated for the FPE's and their supplies (1600 cu ft) is more than adequate. The REPRI program uses the Monte Carlo technique to generate a set of feasible experiment schedules for a space station. The schedules are statistically analyzed to determine the impact of the station experiment program resource requirements on the station concept. Also, the sensitivity of the station concept to one or more resources is assessed.

  3. Medical operations and life sciences activities on space station

    NASA Technical Reports Server (NTRS)

    Johnson, P. C. (Editor); Mason, J. A. (Editor)

    1982-01-01

    Space station health maintenance facilities, habitability, personnel, and research in the medical sciences and in biology are discussed. It is assumed that the space station structure will consist of several modules, each being consistent with Orbiter payload bay limits in size, weight, and center of gravity.

  4. Development of Flow Boiling and Condensation Experiment on the International Space Station- Normal and Low Gravity Flow Boiling Experiment Development and Test Results

    NASA Technical Reports Server (NTRS)

    Nahra, Henry K.; Hall, Nancy R.; Hasan, Mohammad M.; Wagner, James D.; May, Rochelle L.; Mackey, Jeffrey R.; Kolacz, John S.; Butcher, Robert L.; Frankenfield, Bruce J.; Mudawar, Issam; hide

    2013-01-01

    Flow boiling and condensation have been identified as two key mechanisms for heat transport that are vital for achieving weight and volume reduction as well as performance enhancement in future space systems. Since inertia driven flows are demanding on power usage, lower flows are desirable. However, in microgravity, lower flows are dominated by forces other than inertia (like the capillary force). It is of paramount interest to investigate limits of low flows beyond which the flow is inertial enough to be gravity independent. One of the objectives of the Flow Boiling and Condensation Flight Experiment sets to investigate these limits for flow boiling and condensation. A two-phase flow loop consisting of a Flow Boiling Module and two Condensation Modules has been developed to experimentally study flow boiling condensation heat transfer in the reduced gravity environment provided by the reduced gravity platform. This effort supports the development of a flow boiling and condensation facility for the International Space Station (ISS). The closed loop test facility is designed to deliver the test fluid, FC-72 to the inlet of any one of the test modules at specified thermodynamic and flow conditions. The zero-g-aircraft tests will provide subcooled and saturated flow boiling critical heat flux and flow condensation heat transfer data over wide range of flow velocities. Additionally, these tests will verify the performance of all gravity sensitive components, such as evaporator, condenser and accumulator associated with the two-phase flow loop. We will present in this paper the breadboard development and testing results which consist of detailed performance evaluation of the heater and condenser combination in reduced and normal gravity. We will also present the design of the reduced gravity aircraft rack and the results of the ground flow boiling heat transfer testing performed with the Flow Boiling Module that is designed to investigate flow boiling heat transfer and

  5. Cautionary tales for reduced-gravity particle research

    NASA Technical Reports Server (NTRS)

    Marshall, John R.; Greeley, Ronald; Tucker, D. W.

    1987-01-01

    Failure of experiments conducted on the KC-135 aircraft in zero gravity are discussed. Tests that were a total failure are reported. Why the failure occurred and the sort of questions that potential researchers should ask in order to avoid the appearance of abstracts such as this are discussed. Many types of aggregation studies were proposed for the Space Station, and it is hoped that the following synopsis of events will add a touch of reality to experimentation proposed for this zero-gravity environment.

  6. Structure formation in f(T) gravity and a solution for H0 tension

    NASA Astrophysics Data System (ADS)

    Nunes, Rafael C.

    2018-05-01

    We investigate the evolution of scalar perturbations in f(T) teleparallel gravity and its effects on the cosmic microwave background (CMB) anisotropy. The f(T) gravity generalizes the teleparallel gravity which is formulated on the Weitzenböck spacetime, characterized by the vanishing curvature tensor (absolute parallelism) and the non-vanishing torsion tensor. For the first time, we derive the observational constraints on the modified teleparallel gravity using the CMB temperature power spectrum from Planck's estimation, in addition to data from baryonic acoustic oscillations (BAO) and local Hubble constant measurements. We find that a small deviation of the f(T) gravity model from the ΛCDM cosmology is slightly favored. Besides that, the f(T) gravity model does not show tension on the Hubble constant that prevails in the ΛCDM cosmology. It is clear that f(T) gravity is also consistent with the CMB observations, and undoubtedly it can serve as a viable candidate amongst other modified gravity theories.

  7. Spacecraft fire-safety experiments for space station: Technology development mission

    NASA Technical Reports Server (NTRS)

    Youngblood, Wallace W.

    1988-01-01

    Three concept designs for low-gravity, fire-safety related experiments are presented, as selected for the purpose of addressing key issues of enhancing safety and yet encouraging access to long-duration, manned spacecraft such as the NASA space station. The selected low-gravity experiments are the following: (1) an investigation of the flame-spread rate and combustion-product evolution of the burning of typical thicknesses of spacecraft materials in very low-speed flows; (2) an evaluation of the interaction of fires and candidate extinguishers in various fire scenarios; and (3) an investigation of the persistence and propagation of smoldering and deep-seated combustion. Each experiment is expected to provide fundamental combustion-science data, as well as the fire-safety applications, and each requires the unique long-duration, low-gravity environment of the space station. Two generic test facilities, i.e., the Combustion Tunnel Facility and the Combustion Facility, are proposed for space station accommodation to support the selected experiments. In addition, three near-term, fire-safety related experiments are described along with other related precursor activities.

  8. The opportunities for space biology research on the Space Station

    NASA Technical Reports Server (NTRS)

    Ballard, Rodney W.; Souza, Kenneth A.

    1987-01-01

    The goals of space biology research to be conducted aboard the Space Station in 1990s include long-term studies of reproduction, development, growth, physiology, behavior, and aging in both animals and plants. They also include studies of the mechanisms by which gravitational stimuli are sensed, processed, and transmitted to a responsive site, and of the effect of microgravity on each component. The Space Station configuration will include a life sciences research facility, where experiment cyles will be on a 90-day basis (since the Space Station missions planned for the 1990s call for 90-day intervals). A modular approach is taken to accomodate animal habitats, plant growth chambers, and other specimen holding facilities; the modular habitats would be transportable between the launch systems, habitat racks, a workbench, and a variable-gravity centrifuge (included for providing artificial gravity and accurately controlled acceleration levels aboard Space Station).

  9. Nucleate pool boiling: High gravity to reduced gravity; liquid metals to cryogens

    NASA Technical Reports Server (NTRS)

    Merte, Herman, Jr.

    1988-01-01

    Requirements for the proper functioning of equipment and personnel in reduced gravity associated with space platforms and future space station modules introduce unique problems in temperature control; power generation; energy dissipation; the storage, transfer, control and conditioning of fluids; and liquid-vapor separation. The phase change of boiling is significant in all of these. Although both pool and flow boiling would be involved, research results to date include only pool boiling because buoyancy effects are maximized for this case. The effective application of forced convection boiling heat transfer in the microgravity of space will require a well grounded and cogent understanding of the mechanisms involved. Experimental results are presented for pool boiling from a single geometrical configuration, a flat surface, covering a wide range of body forces from a/g = 20 to 1 to a/g = 0 to -1 for a cryogenic liquid, and from a/g = 20 to 1 for water and a liquid metal. Similarities in behavior are noted for these three fluids at the higher gravity levels, and may reasonably be expected to continue at reduced gravity levels.

  10. COMMENT: Comment on 'Evaluation of the local value of the Earth gravity field in the context of the new definition of the kilogram'

    NASA Astrophysics Data System (ADS)

    Svitlov, S. M.

    2010-06-01

    A recent paper (Baumann et al 2009 Metrologia 46 178-86) presents a method to evaluate the free-fall acceleration at a desired point in space, as required for the watt balance experiment. The claimed uncertainty of their absolute gravity measurements is supported by two bilateral comparisons using two absolute gravimeters of the same type. This comment discusses the case where absolute gravity measurements are traceable to a key comparison reference value. Such an approach produces a more complete uncertainty budget and reduces the risk of the results of different watt balance experiments not being compatible.

  11. Low-gravity impact experiments: Progress toward a facility definition

    NASA Technical Reports Server (NTRS)

    Cintala, M. J.

    1986-01-01

    Innumerable efforts were made to understand the cratering process and its ramifications in terms of planetary observations, during which the role of gravity has often come into question. Well known facilities and experiments both were devoted in many cases to unraveling the contribution of gravitational acceleration to cratering mechanisms. Included among these are the explosion experiments in low gravity aircraft, the drop platform experiments, and the high gravity centrifuge experiments. Considerable insight into the effects of gravity was gained. Most investigations were confined to terrestrial laboratories. It is in this light that the Space Station is being examined as a vehicle with the potential to support otherwise impractical impact experiments. The results of studies performed by members of the planetary cratering community are summarized.

  12. MX Siting Investigation, Gravity Survey - Delamar Valley, Nevada.

    DTIC Science & Technology

    1981-07-20

    reduces the data to Simple Bouguer Anomaly (see Section A1.4, Appendix A1.0). The Defense Mapping Agency Aerospace Center (DMAAC), St. Louis, Missouri...DRAWINGS Drawing Number 1 Complete Bouguer Anomaly Contours 2 Depth to Rock -Interpreted from In Pocket at Gravity Data End of Report iv E-TR-33-DM...ErtPX E-TR-3 3-DM 6 2.0 GRAVITY DATA REDUCTION DMAHTC/GSS obtained the basic observations for the new stations and reduced them to Simple Bouguer

  13. Modular space station detailed preliminary design. Volume 1: Sections 1 through 4.4

    NASA Technical Reports Server (NTRS)

    1971-01-01

    Detailed configuration and subsystems preliminary design data are presented for the modular space station concept. Each module comprising the initial space station is described in terms of its external and internal configuration, its functional responsibilities to the initial cluster, and its orbital build up sequence. Descriptions of the subsequent build up to the growth space station are also presented. Analytical and design techniques, tradeoff considerations, and depth of design detail are discussed for each subsystem. The subsystems include the following: structural/mechanical; crew habitability and protection; experiment support; electrical power; environmental control/life support; guidance, navigation, and control; propulsion; communications; data management; and onboard checkout subsystems. The interfaces between the station and other major elements of the program are summarized. The rational for a zero-gravity station, in lieu of one with artificial-gravity capability, is also summarized.

  14. Gravity Data from Newark Valley, White Pine County, Nevada

    USGS Publications Warehouse

    Mankinen, Edward A.; McKee, Edwin H.

    2007-01-01

    The Newark Valley area, eastern Nevada is one of thirteen major ground-water basins investigated by the BARCAS (Basin and Range Carbonate Aquifer Study) Project. Gravity data are being used to help characterize the geophysical framework of the region. Although gravity coverage was extensive over parts of the BARCAS study area, data were sparse for a number of the valleys, including the northern part of Newark Valley. We addressed this lack of data by establishing seventy new gravity stations in and around Newark Valley. All available gravity data were then evaluated to determine their reliability, prior to calculating an isostatic residual gravity map to be used for subsequent analyses. A gravity inversion method was used to calculate depths to pre-Cenozoic basement rock and estimates of maximum alluvial/volcanic fill. The enhanced gravity coverage and the incorporation of lithologic information from several deep oil and gas wells yields a view of subsurface shape of the basin and will provide information useful for the development of hydrogeologic models for the region.

  15. Absolute gravimetry as an operational tool for geodynamics research

    NASA Astrophysics Data System (ADS)

    Torge, W.

    Relative gravimetric techniques have been used for nearly 30 years for measuring non-tidal gravity variations with time, and thus have contributed to geodynamics research by monitoring vertical crustal movements and internal mass shifts. With today's accuracy of about ± 0.05µms-2 (or 5µGal), significant results have been obtained in numerous control nets of local extension, especially in connection with seismic and volcanic events. Nevertheless, the main drawbacks of relative gravimetry, which are deficiencies in absolute datum and calibration, set a limit for its application, especially with respect to large-scale networks and long-term investigations. These problems can now be successfully attacked by absolute gravimetry, with transportable gravimeters available since about 20 years. While the absolute technique during the first two centuries of gravimetry's history was based on the pendulum method, the free-fall method can now be employed taking advantage of laser-interferometry, electronic timing, vacuum and shock absorbing techniques, and on-line computer-control. The accuracy inherent in advanced instruments is about ± 0.05 µms-2. In field work, generally an accuracy of ±0.1 µms-2 may be expected, strongly depending on local environmental conditions.

  16. International Space Station Research Plan: Assembly Sequence. Revised

    NASA Technical Reports Server (NTRS)

    2000-01-01

    These viewgraphs discuss the International Space Station's Research Plan. The goals for the International Space Station Utilization are to provide a state-of-the-art research facility on which to study gravity's effects on physical, chemical, and biological systems. It is also an advanced testbed for technology and human exploration as well as a commercial platform for space research and development.

  17. High-resolution regional gravity field modelling in a mountainous area from terrestrial gravity data

    NASA Astrophysics Data System (ADS)

    Bucha, Blažej; Janák, Juraj; Papčo, Juraj; Bezděk, Aleš

    2016-11-01

    We develop a high-resolution regional gravity field model by a combination of spherical harmonics, band-limited spherical radial basis functions (SRBFs) and the residual terrain model (RTM) technique. As the main input data set, we employ a dense terrestrial gravity database (3-6 stations km-2), which enables gravity field modelling up to very short spatial scales. The approach is based on the remove-compute-restore methodology in which all the parts of the signal that can be modelled are removed prior to the least-squares adjustment in order to smooth the input gravity data. To this end, we utilize degree-2159 spherical harmonic models and the RTM technique using topographic models at 2 arcsec resolution. The residual short-scale gravity signal is modelled via the band-limited Shannon SRBF expanded up to degree 21 600, which corresponds to a spatial resolution of 30 arcsec. The combined model is validated against GNSS/levelling-based height anomalies, independent surface gravity data, deflections of the vertical and terrestrial vertical gravity gradients achieving an accuracy of 2.7 cm, 0.53 mGal, 0.39 arcsec and 279 E in terms of the RMS error, respectively. A key aspect of the combined approach, especially in mountainous areas, is the quality of the RTM. We therefore compare the performance of two RTM techniques within the innermost zone, the tesseroids and the polyhedron. It is shown that the polyhedron-based approach should be preferred in rugged terrain if a high-quality RTM is required. In addition, we deal with the RTM computations at points located below the reference surface of the residual terrain which is known to be a rather delicate issue.

  18. An Experimental and Computational Study on Soot Formation in a Coflow Jet Flame Under Microgravity and Normal Gravity

    NASA Technical Reports Server (NTRS)

    Ma, Bin; Cao, Su; Giassi, Davide; Stocker, Dennis P.; Takahashi, Fumiaki; Bennett, Beth Anne V.; Smooke, Mitchell D.; Long, Marshall B.

    2014-01-01

    Upon the completion of the Structure and Liftoff in Combustion Experiment (SLICE) in March 2012, a comprehensive and unique set of microgravity coflow diffusion flame data was obtained. This data covers a range of conditions from weak flames near extinction to strong, highly sooting flames, and enabled the study of gravitational effects on phenomena such as liftoff, blowout and soot formation. The microgravity experiment was carried out in the Microgravity Science Glovebox (MSG) on board the International Space Station (ISS), while the normal gravity experiment was performed at Yale utilizing a copy of the flight hardware. Computational simulations of microgravity and normal gravity flames were also carried out to facilitate understanding of the experimental observations. This paper focuses on the different sooting behaviors of CH4 coflow jet flames in microgravity and normal gravity. The unique set of data serves as an excellent test case for developing more accurate computational models.Experimentally, the flame shape and size, lift-off height, and soot temperature were determined from line-of-sight flame emission images taken with a color digital camera. Soot volume fraction was determined by performing an absolute light calibration using the incandescence from a flame-heated thermocouple. Computationally, the MC-Smooth vorticity-velocity formulation was employed to describe the chemically reacting flow, and the soot evolution was modeled by the sectional aerosol equations. The governing equations and boundary conditions were discretized on an axisymmetric computational domain by finite differences, and the resulting system of fully coupled, highly nonlinear equations was solved by a damped, modified Newtons method. The microgravity sooting flames were found to have lower soot temperatures and higher volume fraction than their normal gravity counterparts. The soot distribution tends to shift from the centerline of the flame to the wings from normal gravity to

  19. Principal facts for a gravity survey of the Gerlach Extension Known Geothermal Resource Area, Pershing County, Nevada

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Peterson, D.L.; Kaufmann, H.E.

    1978-01-01

    During July 1977, fifty-one gravity stations were obtained in the Gerlach Extension Known Geothermal Resource Area and vicinity, northwestern Nevada. The gravity observations were made with a Worden gravimeter having a scale factor of about 0.5 milligal per division. No terrain corrections have been applied to these data. The earth tide correction was not used in drift reduction. The Geodetic Reference System 1967 formula (International Association of Geodesy, 1967) was used to compute theoretical gravity. Observed gravity is referenced to a base station in Gerlach, Nevada, having a value based on the Potsdam System of 1930. A density of 2.67more » g per cm/sup 3/ was used in computing the Bouguer anomaly.« less

  20. Space Station

    NASA Image and Video Library

    1985-12-01

    Skylab's success proved that scientific experimentation in a low gravity environment was essential to scientific progress. A more permanent structure was needed to provide this space laboratory. President Ronald Reagan, on January 25, 1984, during his State of the Union address, claimed that the United States should exploit the new frontier of space, and directed NASA to build a permanent marned space station within a decade. The idea was that the space station would not only be used as a laboratory for the advancement of science and medicine, but would also provide a staging area for building a lunar base and manned expeditions to Mars and elsewhere in the solar system. President Reagan invited the international community to join with the United States in this endeavour. NASA and several countries moved forward with this concept. By December 1985, the first phase of the space station was well underway with the design concept for the crew compartments and laboratories. Pictured are two NASA astronauts, at Marshall Space Flight Center's (MSFC) Neutral Buoyancy Simulator (NBS), practicing construction techniques they later used to construct the space station after it was deployed.

  1. Walking in a rotating space station, an electromyographic and kinematic study

    NASA Technical Reports Server (NTRS)

    Harris, R. L.

    1975-01-01

    Biomechanics were studied of locomotion in a rotating environment like that of a space station at various gravity levels. Comparisons were made of the walking gait patterns and the amplitudes of various leg muscle electrical outputs at different gravity levels. The results of these tests are applicable to planning future space missions by providing a part of the information that will be needed to determine the type of vehicle and the gravity level to be provided for the astronauts if it is decided that artificial gravity is to be utilized.

  2. Measuring gravity currents in the Chicago River, Chicago, Illinois

    USGS Publications Warehouse

    Oberg, K.A.; Czuba, J.A.; Johnson, K.K.

    2008-01-01

    Recent studies of the Chicago River have determined that gravity currents are responsible for persistent bidirectional flows that have been observed in the river. A gravity current is the flow of one fluid within another caused by a density difference between the fluids. These studies demonstrated how acoustic Doppler current profilers (ADCP) can be used to detect and characterize gravity currents in the field. In order to better understand the formation and evolution of these gravity currents, the U.S. Geological Survey (USGS) has installed ADCPs and other instruments to continuously measure gravity currents in the Chicago River and the North Branch Chicago River. These instruments include stage sensors, thermistor strings, and both upward-looking and horizontal ADCPs. Data loggers and computers installed at gaging stations along the river are used to collect data from these instruments and transmit them to USGS offices. ?? 2008 IEEE.

  3. Autonomous momentum management for space station

    NASA Technical Reports Server (NTRS)

    Hahn, E.

    1984-01-01

    Momentum management for the CDG planar space platform is discussed. It is assumed that the external torques on the space station are gravity gradient and aerodynamic, both have bias and cyclic terms. The integrals of the cyclic torques are the cyclic momenti which will be stored in the momentum storage actuator. Techniques to counteract the bias torques and center the cyclic momentum and gravity gradient desaturation by adjusting vehicle attitude, aerodynamic desaturation using solar panels and radiators and the deployment of flat plates at the end of long booms generating aerodynamic torques are investigated.

  4. Gravity independence of seed-to-seed cycling in Brassica rapa

    NASA Technical Reports Server (NTRS)

    Musgrave, M. E.; Kuang, A.; Xiao, Y.; Stout, S. C.; Bingham, G. E.; Briarty, L. G.; Levenskikh, M. A.; Sychev, V. N.; Podolski, I. G.

    2000-01-01

    Growth of higher plants in the microgravity environment of orbital platforms has been problematic. Plants typically developed more slowly in space and often failed at the reproductive phase. Short-duration experiments on the Space Shuttle showed that early stages in the reproductive process could occur normally in microgravity, so we sought a long-duration opportunity to test gravity's role throughout the complete life cycle. During a 122-d opportunity on the Mir space station, full life cycles were completed in microgravity with Brassica rapa L. in a series of three experiments in the Svet greenhouse. Plant material was preserved in space by chemical fixation, freezing, and drying, and then compared to material preserved in the same way during a high-fidelity ground control. At sampling times 13 d after planting, plants on Mir were the same size and had the same number of flower buds as ground control plants. Following hand-pollination of the flowers by the astronaut, siliques formed. In microgravity, siliques ripened basipetally and contained smaller seeds with less than 20% of the cotyledon cells found in the seeds harvested from the ground control. Cytochemical localization of storage reserves in the mature embryos showed that starch was retained in the spaceflight material, whereas protein and lipid were the primary storage reserves in the ground control seeds. While these successful seed-to-seed cycles show that gravity is not absolutely required for any step in the plant life cycle, seed quality in Brassica is compromised by development in microgravity.

  5. Reliability of Various Measurement Stations for Determining Plantar Fascia Thickness and Echogenicity.

    PubMed

    Bisi-Balogun, Adebisi; Cassel, Michael; Mayer, Frank

    2016-04-13

    This study aimed to determine the relative and absolute reliability of ultrasound (US) measurements of the thickness and echogenicity of the plantar fascia (PF) at different measurement stations along its length using a standardized protocol. Twelve healthy subjects (24 feet) were enrolled. The PF was imaged in the longitudinal plane. Subjects were assessed twice to evaluate the intra-rater reliability. A quantitative evaluation of the thickness and echogenicity of the plantar fascia was performed using Image J, a digital image analysis and viewer software. A sonography evaluation of the thickness and echogenicity of the PF showed a high relative reliability with an Intra class correlation coefficient of ≥0.88 at all measurement stations. However, the measurement stations for both the PF thickness and echogenicity which showed the highest intraclass correlation coefficient (ICCs) did not have the highest absolute reliability. Compared to other measurement stations, measuring the PF thickness at 3 cm distal and the echogenicity at a region of interest 1 cm to 2 cm distal from its insertion at the medial calcaneal tubercle showed the highest absolute reliability with the least systematic bias and random error. Also, the reliability was higher using a mean of three measurements compared to one measurement. To reduce discrepancies in the interpretation of the thickness and echogenicity measurements of the PF, the absolute reliability of the different measurement stations should be considered in clinical practice and research rather than the relative reliability with the ICC.

  6. Reliability of Various Measurement Stations for Determining Plantar Fascia Thickness and Echogenicity

    PubMed Central

    Bisi-Balogun, Adebisi; Cassel, Michael; Mayer, Frank

    2016-01-01

    This study aimed to determine the relative and absolute reliability of ultrasound (US) measurements of the thickness and echogenicity of the plantar fascia (PF) at different measurement stations along its length using a standardized protocol. Twelve healthy subjects (24 feet) were enrolled. The PF was imaged in the longitudinal plane. Subjects were assessed twice to evaluate the intra-rater reliability. A quantitative evaluation of the thickness and echogenicity of the plantar fascia was performed using Image J, a digital image analysis and viewer software. A sonography evaluation of the thickness and echogenicity of the PF showed a high relative reliability with an Intra class correlation coefficient of ≥0.88 at all measurement stations. However, the measurement stations for both the PF thickness and echogenicity which showed the highest intraclass correlation coefficient (ICCs) did not have the highest absolute reliability. Compared to other measurement stations, measuring the PF thickness at 3 cm distal and the echogenicity at a region of interest 1 cm to 2 cm distal from its insertion at the medial calcaneal tubercle showed the highest absolute reliability with the least systematic bias and random error. Also, the reliability was higher using a mean of three measurements compared to one measurement. To reduce discrepancies in the interpretation of the thickness and echogenicity measurements of the PF, the absolute reliability of the different measurement stations should be considered in clinical practice and research rather than the relative reliability with the ICC. PMID:27089369

  7. First independent lunar gravity field solution in the framework of project GRAZIL

    NASA Astrophysics Data System (ADS)

    Wirnsberger, Harald; Krauss, Sandro; Klinger, Beate; Mayer-Gürr, Torsten

    2017-04-01

    The twin satellite mission Gravity Recovery and Interior Laboratory (GRAIL) aims to recovering the lunar gravity field by means of intersatellite Ka-band ranging (KBR) observations. In order to exploit the potential of KBR data, absolute position information of the two probes is required. Hitherto, the Graz lunar gravity field models (GrazLGM) relies on the official orbit products provided by NASA. In this contribution, we present for the first time a completely independent Graz lunar gravity field model to spherical harmonic degree and order 420. The reduced dynamic orbits of the two probes are determined using variational equations following a batch least squares differential adjustment process. These orbits are based on S-band radiometric tracking data collected by the Deep Space Network and are used for the independent GRAIL gravity field recovery. To reveal a highly accurate lunar gravity field, an integral equation approach using short orbital arcs is adopted to process the KBR data. A comparison to state-of-the-art lunar gravity models computed at NASA-GSFC, NASA-JPL and AIUB demonstrate the progress of Graz lunar gravity field models derived within the project GRAZIL.

  8. Surface and subsurface microgravity data in the vicinity of Sanford Underground Research Facility, Lead, South Dakota

    USGS Publications Warehouse

    Kennedy, Jeffrey R.; Koth, Karl R.; Carruth, Rob

    2015-01-01

    Absolute gravity data were collected at 32 stations in the vicinity of the Sanford Underground Research Facility from 2007 through 2014 for the purpose of monitoring groundwater storage change during dewatering of the former Homestake gold mine in the Black Hills of South Dakota, the largest and deepest underground mine in North America. Eight underground stations are at depths from 300 feet below land surface to 4,850 feet below land surface. Surface stations were located using Global Positioning System observations, and subsurface stations were located on the basis of maps constructed from survey measurements made while the mine was in operation. Gravity varies widely at many stations; however, no consistent temporal trends are present across all stations during the 7-year period of data collection.

  9. Position of the station Borowiec in the Doppler observation campaign WEDOC 80

    NASA Astrophysics Data System (ADS)

    Pachelski, W.

    The position of the Doppler antenna located at the Borowiec Observatory, Poland, is analyzed based on data gathered during the WEDOC 80 study and an earlier study in 1977. Among other findings, it is determined that biases of the reference system origin can be partially eliminated by transforming absolute coordinates of two or more stations into station-to-station vector components, and by determining the vector length while the system scale remains affected by broadcast ephemerides. The standard deviations of absolute coordinates are shown to represent only the internal accuracy of the solution, and are found to depend on the geometrical configuration between the station position and the satellite passes. It is shown that significant correlations between station coordinates in translocation or multilocation are due to the poor conditioning of design matrices with respect to the origin and orientation of the reference system.

  10. Principal facts for a gravity survey of the Fly Ranch Extension Known Geothermal Resource Area, Pershing County, Nevada

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Peterson, D.L.; Kaufmann, H.E.

    1978-01-01

    During July 1977, forty-four gravity stations were obtained in the Fly Ranch Extension Known Geothermal Resource Area and vicinity, northwestern Nevada. The gravity observations were made with a Worden gravimeter having a scale factor of about 0.5 milligal per division. No terrain corrections have been applied to these data. The earth tide correction was not used in drift reduction. The Geodetic Reference System 1967 formula (International Association of Geodesy, 1967) was used to compute theoretical gravity. Observed gravity is referenced to a base station in Gerlach, Nevada, having a value based on the Potsdam System of 1930 (fig. 1). Amore » density of 2.67 g per cm/sup 3/ was used in computing the Bouguer anomaly.« less

  11. OSSA Space Station Freedom science utilization plans

    NASA Astrophysics Data System (ADS)

    Cressy, Philip J.

    Long duration exposure to an essentially zero-gravity environment is a phenomenon exclusive to the Space Station Freedom that cannot be duplicated on Earth. The Freedom Station will offer periods of time on orbit extending to weeks and months rather than hours or days, allowing for in-depth space based research and analysis to a degree never before achieved. OSSA remains committed to exploiting the unique capabilities provided by the Space Station as well as other space-based facilities to study the nature of physical, chemical, and biological processes in a low-gravity environment and to apply these studies to advance science and applications in such fields as biomedical research, plant and animal physiology, exobiology, biotechnology, materials science, fluid physics, and combustion science. The OSSA focus is on progressive science investigations, many requiring hands-on scientist involvement using sophisticated experiment hardware. OSSA science utilization planning for the Freedom Station is firmly established. For this presentation, this planning is discussed in three general areas: OSSA goals and overall approach, the current and on-going program, and plans for space station utilization. In the first area, OSSA addresses its overall approach to space science research, its commitment to transition to Space Station Freedom, and its top-level strategy for the utilization of Freedom. The current and on-going program is next discussed, focusing on the various Spacelab series of missions which are providing the stepping-stones to Space Station Freedom. Selected science results from SLS-1 and USML-1 are cited which underline the value of properly outfitted laboratories in space in which crew-intensive experiment interactions are possible. The presentation is concluded with a discussion of top-level goals and strategies for utilizing the Freedom Station by OSSA's Life Sciences Division and its Microgravity Science and Applications Division.

  12. OSSA Space Station Freedom science utilization plans

    NASA Technical Reports Server (NTRS)

    Cressy, Philip J.

    1992-01-01

    Long duration exposure to an essentially zero-gravity environment is a phenomenon exclusive to the Space Station Freedom that cannot be duplicated on Earth. The Freedom Station will offer periods of time on orbit extending to weeks and months rather than hours or days, allowing for in-depth space based research and analysis to a degree never before achieved. OSSA remains committed to exploiting the unique capabilities provided by the Space Station as well as other space-based facilities to study the nature of physical, chemical, and biological processes in a low-gravity environment and to apply these studies to advance science and applications in such fields as biomedical research, plant and animal physiology, exobiology, biotechnology, materials science, fluid physics, and combustion science. The OSSA focus is on progressive science investigations, many requiring hands-on scientist involvement using sophisticated experiment hardware. OSSA science utilization planning for the Freedom Station is firmly established. For this presentation, this planning is discussed in three general areas: OSSA goals and overall approach, the current and on-going program, and plans for space station utilization. In the first area, OSSA addresses its overall approach to space science research, its commitment to transition to Space Station Freedom, and its top-level strategy for the utilization of Freedom. The current and on-going program is next discussed, focusing on the various Spacelab series of missions which are providing the stepping-stones to Space Station Freedom. Selected science results from SLS-1 and USML-1 are cited which underline the value of properly outfitted laboratories in space in which crew-intensive experiment interactions are possible. The presentation is concluded with a discussion of top-level goals and strategies for utilizing the Freedom Station by OSSA's Life Sciences Division and its Microgravity Science and Applications Division.

  13. Principal facts for gravity data along the Hayward fault and vicinity, San Francisco Bay area, northern California

    USGS Publications Warehouse

    Ponce, David A.

    2001-01-01

    The U.S. Geological Survey (USGS) established over 940 gravity stations along the Hayward fault and vicinity. The Hayward fault, regarded as one of the most hazardous faults in northern California (Working Group on California Earthquake Probabilities, 1999), extends for about 90 km from Fremont in the southeast to San Pablo Bay in the northwest. The Hayward fault is predominantly a right-lateral strike-slip fault that forms the western boundary of the East Bay Hills. These data and associated physical property measurement were collected as part of on-going studies to help determine the earthquake hazard potential of major faults within the San Francisco Bay region. Gravity data were collected between latitude 37°30' and 38°15' N and longitude 121°45' and 122°30' W. Gravity stations were located on the following 7.5 minute quadrangles: Newark, Niles, San Leandro, Hayward, Dublin, Oakland West, Oakland East, Las Trampas Ridge, Diablo, Richmond, Briones Valley, Walnut Creek, and Clayton. All data were ultimately tied to primary gravity base station Menlo Park A, located on the campus of the U.S. Geological Survey in Menlo Park, Calif. (latitude 37°27.34' N, longitude 122°10.18' W, observed gravity value 979944.27 mGal).

  14. Effect of Time Varying Gravity on DORIS processing for ITRF2013

    NASA Astrophysics Data System (ADS)

    Zelensky, N. P.; Lemoine, F. G.; Chinn, D. S.; Beall, J. W.; Melachroinos, S. A.; Beckley, B. D.; Pavlis, D.; Wimert, J.

    2013-12-01

    Computations are under way to develop a new time series of DORIS SINEX solutions to contribute to the development of the new realization of the terrestrial reference frame (c.f. ITRF2013). One of the improvements that are envisaged is the application of improved models of time-variable gravity in the background orbit modeling. At GSFC we have developed a time series of spherical harmonics to degree and order 5 (using the GOC02S model as a base), based on the processing of SLR and DORIS data to 14 satellites from 1993 to 2013. This is compared with the standard approach used in ITRF2008, based on the static model EIGEN-GL04S1 which included secular variations in only a few select coefficients. Previous work on altimeter satellite POD (c.f. TOPEX/Poseidon, Jason-1, Jason-2) has shown that the standard model is not adequate and orbit improvements are observed with application of more detailed models of time-variable gravity. In this study, we quantify the impact of TVG modeling on DORIS satellite POD, and ascertain the impact on DORIS station positions estimated weekly from 1993 to 2013. The numerous recent improvements to SLR and DORIS processing at GSFC include a more complete compliance to IERS2010 standards, improvements to SLR/DORIS measurement modeling, and improved non-conservative force modeling to DORIS satellites. These improvements will affect gravity coefficient estimates, POD, and the station solutions. Tests evaluate the impact of time varying gravity on tracking data residuals, station consistency, and the geocenter and scale reference frame parameters.

  15. An improved model for the Earth's gravity field

    NASA Technical Reports Server (NTRS)

    Tapley, B. D.; Shum, C. K.; Yuan, D. N.; Ries, J. C.; Schutz, B. E.

    1989-01-01

    An improved model for the Earth's gravity field, TEG-1, was determined using data sets from fourteen satellites, spanning the inclination ranges from 15 to 115 deg, and global surface gravity anomaly data. The satellite measurements include laser ranging data, Doppler range-rate data, and satellite-to-ocean radar altimeter data measurements, which include the direct height measurement and the differenced measurements at ground track crossings (crossover measurements). Also determined was another gravity field model, TEG-1S, which included all the data sets in TEG-1 with the exception of direct altimeter data. The effort has included an intense scrutiny of the gravity field solution methodology. The estimated parameters included geopotential coefficients complete to degree and order 50 with selected higher order coefficients, ocean and solid Earth tide parameters, Doppler tracking station coordinates and the quasi-stationary sea surface topography. Extensive error analysis and calibration of the formal covariance matrix indicate that the gravity field model is a significant improvement over previous models and can be used for general applications in geodesy.

  16. pyGrav, a Python-based program for handling and processing relative gravity data

    NASA Astrophysics Data System (ADS)

    Hector, Basile; Hinderer, Jacques

    2016-06-01

    pyGrav is a Python-based open-source software dedicated to the complete processing of relative-gravity data. It is particularly suited for time-lapse gravity surveys where high precision is sought. Its purpose is to bind together single-task processing codes in a user-friendly interface for handy and fast treatment of raw gravity data from many stations of a network. The intuitive object-based implementation allows to easily integrate additional functions (reading/writing routines, processing schemes, data plots) related to the appropriate object (a station, a loop, or a survey). This makes pyGrav an evolving tool. Raw data can be corrected for tides and air pressure effects. The data selection step features a double table-plot graphical window with either manual or automatic selection according to specific thresholds on data channels (tilts, gravity values, gravity standard deviation, duration of measurements, etc.). Instrumental drifts and gravity residuals are obtained by least square analysis of the dataset. This first step leads to the gravity simple differences between a reference point and any point of the network. When different repetitions of the network are done, the software computes then the gravity double differences and associated errors. The program has been tested on two specific case studies: a large dataset acquired for the study of water storage changes on a small catchment in West Africa, and a dataset operated and processed by several different users for geothermal studies in northern Alsace, France. In both cases, pyGrav proved to be an efficient and easy-to-use solution for the effective processing of relative-gravity data.

  17. Acoustic gravity microseismic pressure signal at shallow stations

    NASA Astrophysics Data System (ADS)

    Peureux, Charles; Ardhuin, Fabrice; Royer, Jean-Yves

    2017-04-01

    It has been known for decades that the background permanent seismic noise, the so-called microseimic signal, is generated by the nonlinear interaction of oppositely travelling ocean surface waves [Longuet-Higgins 1951]. It can especially be used to infer the time variability of short ocean waves statistics [Peureux and Ardhuin 2016]. However, better quantitative estimates of the latter are made difficult due to a poor knowledge of the Earth's crust characteristics, whose coupling with acoustic modes can affect large uncertainties to the frequency response at the bottom of the ocean. The pressure field at depths less than an acoustic wave length to the surface is made of evanescent acoustic-gravity modes [Cox and Jacobs 1989]. For this reason, they are less affected by the ocean bottom composition. This near field is recorded and analyzed in the frequency range 0.1 to 0.5 Hz approximately, at two locations : at a shallow site in the North-East Atlantic continental shelf and a deep water site in the Southern Indian ocean, at the ocean bottom and 100 m below sea-surface and in the upper part of the water column respectively. Evanescent and propagating Rayleigh modes are compared against theoretical predictions. Comparisons against surface waves hindcast based on WAVEWATCH(R) III modelling framework help assessing its performances and can be used to help future model improvements. References Longuet-Higgins, M. S., A Theory of the Origin of Microseisms, Philos. Trans. Royal Soc. A, The Royal Society, 1950, 243, 1-3. Peureux, C. and Ardhuin, F., Ocean bottom pressure records from the Cascadia array and short surface gravity waves, J. Geophys. Res. Oceans, 2016, 121, 2862-2873. Cox, C. S. & Jacobs, D. C., Cartesian diver observations of double frequency pressure fluctuations in the upper levels of the ocean, Geophys. Res. Lett., 1989, 16, 807-810.

  18. 33-Foot-Diameter Space Station Leading to Space Base

    NASA Technical Reports Server (NTRS)

    1969-01-01

    This picture illustrates a concept of a 33-Foot-Diameter Space Station Leading to a Space Base. In-house work of the Marshall Space Flight Center, as well as a Phase B contract with the McDornel Douglas Astronautics Company, resulted in a preliminary design for a space station in 1969 and l970. The Marshall-McDonnel Douglas approach envisioned the use of two common modules as the core configuration of a 12-man space station. Each common module was 33 feet in diameter and 40 feet in length and provided the building blocks, not only for the space station, but also for a 50-man space base. Coupled together, the two modules would form a four-deck facility: two decks for laboratories and two decks for operations and living quarters. Zero-gravity would be the normal mode of operation, although the station would have an artificial gravity capability. This general-purpose orbital facility was to provide wide-ranging research capabilities. The design of the facility was driven by the need to accommodate a broad spectrum of activities in support of astronomy, astrophysics, aerospace medicine, biology, materials processing, space physics, and space manufacturing. To serve the needs of Earth observations, the station was to be placed in a 242-nautical-mile orbit at a 55-degree inclination. An Intermediate-21 vehicle (comprised of Saturn S-IC and S-II stages) would have launched the station in 1977.

  19. Centrifuge Facility for the International Space Station Alpha

    NASA Technical Reports Server (NTRS)

    Johnson, Catherine C.; Hargens, Alan R.

    1994-01-01

    The Centrifuge Facility planned for the International Space Station Alpha has under-one considerable redesign over the past year, primarily because the Station is now viewed as a 10 year mission rather than a 30 year mission and because of the need to simply the design to meet budget constraints and a 2000 launch date. The basic elements of the Centrifuge Facility remain the same, i.e., a 2.5 m diameter centrifuge, a micro-g holding unit, plant and animal habitats, a glovebox and a service unit. The centrifuge will still provide the full range of artificial gravity from 0.01 a to 2 - as originally planned; however, the extractor to permit withdrawal of habitats from the centrifuge without stopping the centrifuge has been eliminated. The specimen habitats have also been simplified and are derived from other NASA programs. The Plant Research Unit being developed by the Gravitational Biology Facility will be used to house plants in the Centrifuge Facility. Although not as ambitious as the Centrifuge Facility plant habitat, it will provide much better environmental control and lighting than the current Shuttle based Plant Growth Facility. Similarly, rodents will be housed in the Advanced Animal Habitat being developed for the Shuttle program. The Centrifuge Facility and ISSA will provide the opportunity to perform repeatable, high quality science. The long duration increments available on the Station will permit multigeneration studies on both plants and animals which have not previously been possible. The Centrifuge Facility will accommodate sufficient number of specimens to permit statistically significant sampling of specimens to investigate the time course of adaptation to altered gravity environments. The centrifuge will for the first time permit investigators to use gravity itself as a tool to investigate fundamental processes, to investigate the intensity and duration of gravity to maintain normal structure and function, to separate the effects of micro-g from

  20. MX Siting Investigation. Gravity Survey - Southern Snake Valley (Ferguson Desert), Utah.

    DTIC Science & Technology

    1980-03-28

    Topographic Center (DMAHTC), head- quartered in Cheyenne, Wyoming. DMAHTC reduces the data to Simple Bouguer Anomaly (see Section A1.4, Appendix Al.0...Valley, Utah . . . . . ......... . . . . . 3 3 Complete Bouguer Anomaly Contours 4 Interpreted Gravity Profile SE-3,4 5 Interpreted Gravity Profile SE...observations and reduced them to Simple Bouguer Anomalies (SBA) for each station as described in Appendix Al.0. Up to three levels of terrain corrections were

  1. Gravity survey in part of the Snake River Plain, Idaho - a preliminary report

    USGS Publications Warehouse

    Baldwin, Harry L.; Hill, David P.

    1960-01-01

    During the early summer of 1959, a total of 1,187 gravity stations were occupied on the western part of the Snake River plain in Idaho. An area of 2,000 square miles extending from Glenns Ferry, Idaho, to Caldwell, Idaho, was covered with a station density of one station per two square miles. An additional 1,200 square miles of surrounding area, mainly from Caldwell, Idaho, to the Oregon-Idaho state line, was covered with a density of one station per seven square miles. The mean reproducibility of the observed gravities of these stations was 0.05 milligal, with a maximum discrepancy of 0.2 milligal. Gravity data were reduced to simple Bouguer values using a combined free-air and Bouguer correction of 0.06 milligal per foot. The only anomalies found with closure in excess of 10 milligals are two elongated highs, orientated northwest-southeast, with the northwestern high offset to the northeast by 10 miles. The smaller of these highs extends from Meridian, Idaho, to Nyssa, Oregon, and the larger extends from Swan Falls, Idaho, to Glenns Ferry, Idaho. The maximum value recorded is a simple Bouguer value of -66.5 milligals with respect to the International Ellipsoid. Gradients on the sides of these highs are largest on the northeast sides, reaching six milligals per mile in places. Graticule interpretations of a profile across the southeastern high using a density contrast of 0.3 gm per cubic centimeter indicate an accumulation of lava reaching a thickness of at least 28,000 feet. The Snake River investigation was made for the purpose of searching out, defining, and interpreting gravity anomalies present on the western part of the Snake River lava plain in Idaho. In particular, it was desired to further define gradients associated with the gravity high shown by the regional work of Bonini and Lavin (1957). It was not planned to cover any specific area, but rather to let the observed anomalies determine the course of the field work. The study was undertaken as part of a

  2. Absolute flux density calibrations of radio sources: 2.3 GHz

    NASA Technical Reports Server (NTRS)

    Freiley, A. J.; Batelaan, P. D.; Bathker, D. A.

    1977-01-01

    A detailed description of a NASA/JPL Deep Space Network program to improve S-band gain calibrations of large aperture antennas is reported. The program is considered unique in at least three ways; first, absolute gain calibrations of high quality suppressed-sidelobe dual mode horns first provide a high accuracy foundation to the foundation to the program. Second, a very careful transfer calibration technique using an artificial far-field coherent-wave source was used to accurately obtain the gain of one large (26 m) aperture. Third, using the calibrated large aperture directly, the absolute flux density of five selected galactic and extragalactic natural radio sources was determined with an absolute accuracy better than 2 percent, now quoted at the familiar 1 sigma confidence level. The follow-on considerations to apply these results to an operational network of ground antennas are discussed. It is concluded that absolute gain accuracies within + or - 0.30 to 0.40 db are possible, depending primarily on the repeatability (scatter) in the field data from Deep Space Network user stations.

  3. Gravity and Heater Size Effects on Pool Boiling Heat Transfer

    NASA Technical Reports Server (NTRS)

    Kim, Jungho; Raj, Rishi

    2014-01-01

    The current work is based on observations of boiling heat transfer over a continuous range of gravity levels between 0g to 1.8g and varying heater sizes with a fluorinert as the test liquid (FC-72/n-perfluorohexane). Variable gravity pool boiling heat transfer measurements over a wide range of gravity levels were made during parabolic flight campaigns as well as onboard the International Space Station. For large heaters and-or higher gravity conditions, buoyancy dominated boiling and heat transfer results were heater size independent. The power law coefficient for gravity in the heat transfer equation was found to be a function of wall temperature under these conditions. Under low gravity conditions and-or for smaller heaters, surface tension forces dominated and heat transfer results were heater size dependent. A pool boiling regime map differentiating buoyancy and surface tension dominated regimes was developed along with a unified framework that allowed for scaling of pool boiling over a wide range of gravity levels and heater sizes. The scaling laws developed in this study are expected to allow performance quantification of phase change based technologies under variable gravity environments eventually leading to their implementation in space based applications.

  4. The gravity field observations and products at IGFS

    NASA Astrophysics Data System (ADS)

    Barzaghi, Riccardo; Vergos, George; Bonvalot, Sylvain; Barthelmes, Franz; Reguzzoni, Mirko; Wziontek, Hartmut; Kelly, Kevin

    2017-04-01

    The International Gravity Field Service (IGFS) is a service of the International Association of Geodesy (IAG) that was established in 2003 at the IAG/IUGG General Assembly in Sapporo (Japan). This service aims at coordinating the actions of the IAG services related to the Earth gravity field, i.e. the Bureau Gravimétrique International (BGI), the International Service for the Geoid (ISG), the International Geodynamics and Earth Tides Service (IGETS), the International Center for Global Earth Models (ICGEM) and the International Digital Elevation Model Service (IDEMS). Also, via its Central Bureau hosted at the Aristotle University of Thessaloniki (Greece), IGFS provides a link to the Global Geodetic Observing System (GGOS) bureaus in order to communicate their requirements and recommendations to the IGFS-Centers. In this work, a presentation is given on the recent activities of the service, namely those related to the contributions to the implementation of: the International Height Reference System/Frame; the Global Geodetic Reference System/Frame; the new Global Absolute Gravity Reference System/Frame. Particularly, the impact that these activities have in improving the estimation of the Earth's gravity field, either at global and local scale, is highlighted also in the framework of GGOS.

  5. 98. (Credit BLV) Detail of gravity, flow conduit intake at ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    98. (Credit BLV) Detail of gravity, flow conduit intake at cross Lake dam Cribbing supports extra suction intake installed in 1930. - McNeil Street Pumping Station, McNeil Street & Cross Bayou, Shreveport, Caddo Parish, LA

  6. Isostatic gravity map of the Death Valley ground-water model area, Nevada and California

    USGS Publications Warehouse

    Ponce, D.A.; Blakely, R.J.; Morin, R.L.; Mankinen, E.A.

    2001-01-01

    An isostatic gravity map of the Death Valley groundwater model area was prepared from over 40,0000 gravity stations as part of an interagency effort by the U.S. Geological Survey and the U.S. Department of Energy to help characterize the geology and hydrology of southwest Nevada and parts of California.

  7. Animal research facility for Space Station Freedom

    NASA Technical Reports Server (NTRS)

    Bonting, Sjoerd L.

    1992-01-01

    An integrated animal research facility is planned by NASA for Space Station Freedom which will permit long-term, man-tended experiments on the effects of space conditions on vertebrates. The key element in this facility is a standard type animal habitat which supports and maintains the animals under full bioisolation during transport and during the experiment. A holding unit accommodates the habitats with animals to be maintained at zero gravity; and a centrifuge, those to be maintained at artificial gravity for control purposes or for gravity threshold studies. A glovebox permits handling of the animals for experimental purposes and for transfer to a clean habitat. These facilities are described, and the aspects of environmental control, monitoring, and bioisolation are discussed.

  8. Validation of Mean Absolute Sea Level of the North Atlantic obtained from Drifter, Altimetry and Wind Data

    NASA Technical Reports Server (NTRS)

    Maximenko, Nikolai A.

    2003-01-01

    Mean absolute sea level reflects the deviation of the Ocean surface from geoid due to the ocean currents and is an important characteristic of the dynamical state of the ocean. Values of its spatial variations (order of 1 m) are generally much smaller than deviations of the geoid shape from ellipsoid (order of 100 m) that makes the derivation of the absolute mean sea level a difficult task for gravity and satellite altimetry observations. Technique used by Niiler et al. for computation of the absolute mean sea level in the Kuroshio Extension was then developed into more general method and applied by Niiler et al. (2003b) to the global Ocean. The method is based on the consideration of balance of horizontal momentum.

  9. Mapping experiment with space station

    NASA Technical Reports Server (NTRS)

    Wu, Sherman S. C.

    1987-01-01

    Mapping the earth from space stations can be approached in two areas. One is to collect gravity data for defining a new topographic datum using the earth's gravitational field in terms of spherical harmonics. The other, which should be considered as a very significant contribution of the Space Station, is to search and explore techniques of mapping the earth's topography using either optical or radar images with or without references to ground control points. Geodetic position of ground control points can be predetermined by the Global Positioning System (GPS) for the mapping experiment with the Space Station. It is proposed to establish four ground control points in North America or Africa (including the Sahara Desert). If this experiment should be successfully accomplished, it may also be applied to the defense charting service.

  10. SOAR 89: Space Station. Space suit test program

    NASA Technical Reports Server (NTRS)

    Kosmo, Joseph J.; West, Philip; Rouen, Michael

    1990-01-01

    The elements of the test program for the space suit to be used on Space Station Freedom are noted in viewgraph form. Information is given on evaluation objectives, zero gravity evaluation, mobility evaluation, extravehicular activity task evaluation, and shoulder joint evaluation.

  11. Using the IMS infrasound network for the identification of mountain-associated waves and gravity waves hotspots

    NASA Astrophysics Data System (ADS)

    Hupe, Patrick; Ceranna, Lars; Pilger, Christoph; Le Pichon, Alexis

    2017-04-01

    The infrasound network of the International Monitoring System (IMS) has been established for monitoring the atmosphere to detect violations of the Comprehensive nuclear-Test-Ban Treaty (CTBT). The IMS comprises 49 certified infrasound stations which are globally distributed. Each station provides data for up to 16 years. Due to the uniform distribution of the stations, the IMS infrasound network can be used to derive global information on atmospheric dynamics' features. This study focuses on mountain-associated waves (MAWs), i.e. acoustic waves in the frequency range between approximately 0.01 Hz and 0.05 Hz. MAWs can be detected in infrasound data by applying the Progressive Multi-Channel Correlation (PMCC) algorithm. As a result of triangulation, global hotspots of MAWs can be identified. Previous studies on gravity waves indicate that global hotspots of gravity waves are similar to those found for MAWs by using the PMCC algorithm. The objective of our study is an enhanced understanding of the excitation sources and of possible interactions between MAWs and gravity waves. Therefore, spatial and temporal correlation analyses will be performed. As a preceding step, we will present (seasonal) hotspots of MAWs as well as hotspots of gravity waves derived by the IMS infrasound network.

  12. Simulated building energy demand biases resulting from the use of representative weather stations

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Burleyson, Casey D.; Voisin, Nathalie; Taylor, Z. Todd

    Numerical building models are typically forced with weather data from a limited number of “representative cities” or weather stations representing different climate regions. The use of representative weather stations reduces computational costs, but often fails to capture spatial heterogeneity in weather that may be important for simulations aimed at understanding how building stocks respond to a changing climate. We quantify the potential reduction in bias from using an increasing number of weather stations over the western U.S. The approach is based on deriving temperature and load time series using incrementally more weather stations, ranging from 8 to roughly 150, tomore » capture weather across different seasons. Using 8 stations, one from each climate zone, across the western U.S. results in an average absolute summertime temperature bias of 7.2°F with respect to a spatially-resolved gridded dataset. The mean absolute bias drops to 2.8°F using all available weather stations. Temperature biases of this magnitude could translate to absolute summertime mean simulated load biases as high as 13.8%, a significant error for capacity expansion planners who may use these types of simulations. Increasing the size of the domain over which biases are calculated reduces their magnitude as positive and negative biases may cancel out. Using 8 representative weather stations can lead to a 20-40% overestimation of peak building loads during both summer and winter. Using weather stations close to population centers reduces both mean and peak load biases. This approach could be used by others designing aggregate building simulations to understand the sensitivity to their choice of weather stations used to drive the models.« less

  13. Space Station Biological Research Project

    NASA Technical Reports Server (NTRS)

    Johnson, Catherine C.; Hargens, Alan R.; Wade, Charles E.

    1995-01-01

    NASA Ames Research Center is responsible for the development of the Space Station Biological Research Project (SSBRP) which will support non-human life sciences research on the International Space Station Alpha (ISSA). The SSBRP is designed to support both basic research to understand the effect of altered gravity fields on biological systems and applied research to investigate the effects of space flight on biological systems. The SSBRP will provide the necessary habitats to support avian and reptile eggs, cells and tissues, plants and rodents. In addition a habitat to support aquatic specimens will be provided by our international partners. Habitats will be mounted in ISSA compatible racks at u-g and will also be mounted on a 2.5 m diameter centrifuge except for the egg incubator which has an internal centrifuge. The 2.5 m centrifuge will provide artificial gravity levels over the range of 0.01 G to 2 G. The current schedule is to launch the first rack in 1999, the Life Sciences glovebox and a second rack early in 2001, a 4 habitat 2.5 in centrifuge later the same year in its own module, and to upgrade the centrifuge to 8 habitats in 2004. The rodent habitats will be derived from the Advanced Animal Habitat currently under development for the Shuttle program and will be capable of housing either rats or mice individually or in groups (6 rats/group and at least 12 mice/group). The egg incubator will be an upgraded Avian Development Facility also developed for the Shuttle program through a Small Business and Innovative Research grant. The Space Tissue Loss cell culture apparatus, developed by Walter Reed Army Institute of Research, is being considered for the cell and tissue culture habitat. The Life Sciences Glovebox is crucial to all life sciences experiments for specimen manipulation and performance of science procedures. It will provide two levels of containment between the work volume and the crew through the use of seals and negative pressure. The glovebox

  14. Integrated dynamic analysis simulation of space stations with controllable solar array

    NASA Technical Reports Server (NTRS)

    Heinrichs, J. A.; Fee, J. J.

    1972-01-01

    A methodology is formulated and presented for the integrated structural dynamic analysis of space stations with controllable solar arrays and non-controllable appendages. The structural system flexibility characteristics are considered in the dynamic analysis by a synthesis technique whereby free-free space station modal coordinates and cantilever appendage coordinates are inertially coupled. A digital simulation of this analysis method is described and verified by comparison of interaction load solutions with other methods of solution. Motion equations are simulated for both the zero gravity and artificial gravity (spinning) orbital conditions. Closed loop controlling dynamics for both orientation control of the arrays and attitude control of the space station are provided in the simulation by various generic types of controlling systems. The capability of the simulation as a design tool is demonstrated by utilizing typical space station and solar array structural representations and a specific structural perturbing force. Response and interaction load solutions are presented for this structural configuration and indicate the importance of using an integrated type analysis for the predictions of structural interactions.

  15. Modification of the gravity model and application to the metropolitan Seoul subway system.

    PubMed

    Goh, Segun; Lee, Keumsook; Park, Jong Soo; Choi, M Y

    2012-08-01

    The Metropolitan Seoul Subway system is examined through the use of the gravity model. Exponents describing the power-law dependence on the time distance between stations are obtained, which reveals a universality for subway lines of the same topology. In the short (time) distance regime the number of passengers between stations does not grow with the decrease in the distance, thus deviating from the power-law behavior. It is found that such reduction in passengers is well described by the Hill function. Further, temporal fluctuations in the passenger flow data, fitted to the gravity model modified by the Hill function, are analyzed to reveal the Yule-type nature inherent in the structure of Seoul.

  16. The network adjustment aimed for the campaigned gravity survey using a Bayesian approach: methodology and model test

    NASA Astrophysics Data System (ADS)

    Chen, Shi; Liao, Xu; Ma, Hongsheng; Zhou, Longquan; Wang, Xingzhou; Zhuang, Jiancang

    2017-04-01

    The relative gravimeter, which generally uses zero-length springs as the gravity senor, is still as the first choice in the field of terrestrial gravity measurement because of its efficiency and low-cost. Because the drift rate of instrument can be changed with the time and meter, it is necessary for estimating the drift rate to back to the base or known gravity value stations for repeated measurement at regular hour's interval during the practical survey. However, the campaigned gravity survey for the large-scale region, which the distance of stations is far away from serval or tens kilometers, the frequent back to close measurement will highly reduce the gravity survey efficiency and extremely time-consuming. In this paper, we proposed a new gravity data adjustment method for estimating the meter drift by means of Bayesian statistical interference. In our approach, we assumed the change of drift rate is a smooth function depend on the time-lapse. The trade-off parameters were be used to control the fitting residuals. We employed the Akaike's Bayesian Information Criterion (ABIC) for the estimated these trade-off parameters. The comparison and analysis of simulated data between the classical and Bayesian adjustment show that our method is robust and has self-adaptive ability for facing to the unregularly non-linear meter drift. At last, we used this novel approach to process the realistic campaigned gravity data at the North China. Our adjustment method is suitable to recover the time-varied drift rate function of each meter, and also to detect the meter abnormal drift during the gravity survey. We also defined an alternative error estimation for the inversed gravity value at the each station on the basis of the marginal distribution theory. Acknowledgment: This research is supported by Science Foundation Institute of Geophysics, CEA from the Ministry of Science and Technology of China (Nos. DQJB16A05; DQJB16B07), China National Special Fund for Earthquake

  17. Electric fields in micro-gravity can replace gravity

    NASA Astrophysics Data System (ADS)

    Gorgolewski, S.

    The influence of the world-wide atmospheric electric field on the growth of plants seems to have been neglected. The confirmation of the existence of electrotropism shows effects on some plants similar to gravity. I propose space ex eriments withp plants that grow in microgravity but are exposed to different electric field configurations with various field strengths and polarity. The electric field in terrestrial environment shows strong effects on some plants that can be regarded as due to phototropism. In microgravity we have full control of light and electric field, and thus we can practically eliminate the effects of gravity and we can study to what degree the electric field can replace the gravitational effects on plants. In this way we can create a new habitat for some plants and study its role in the rate of growth as well as in the sensing of free space for growth of plants in absence of gravity. By varying the strength and direction of illumination of plants we can also study the relative role of phototropism and electrotropism on different plants. This should enable us to select the most suitable plants for Advanced Life Support systems (ALS) for long-duration missions in microgravity environment. Some simple space experiments for verification of these assumptions are described that should answer the basic questions how should we design the ALS for the future high performance space stations and long duration manned space flights. The selection of the suitable plants for such ALS may go along two approaches: the self supporting electrotropic plants using the optimal electric field strength and its range of variation, non electrotropic plants that creep along the "ground" or other supporting plants or special structures. Ground based fitotron experiments have shown that several kV/m electric fields overwhelm the gravity better than clinostats can do. It happens in case of electrotropic plants but also after several days for non-electrotropic plants

  18. Analysis of a rotating advanced-technology space station for the year 2025

    NASA Technical Reports Server (NTRS)

    Queijo, M. J.; Butterfield, A. J.; Cuddihy, W. F.; King, C. B.; Stone, R. W.; Garn, P. A.

    1988-01-01

    An analysis is made of several aspects of an advanced-technology rotating space station configuration generated under a previous study. The analysis includes examination of several modifications of the configuration, interface with proposed launch systems, effects of low-gravity environment on human subjects, and the space station assembly sequence. Consideration was given also to some aspects of space station rotational dynamics, surface charging, and the possible application of tethers.

  19. Gravity Reception and Cardiac Function in the Spider

    NASA Technical Reports Server (NTRS)

    Finck, A.

    1985-01-01

    The following features of the arachnid gravity system were studied. (1) the absolute threshold to hyper-gz is quite low indicating fine proprioreceptive properties of the lyriform organ, the Gz/vibration detector; (2) the neurogenic heart of the spider is a good dependent variable for assessing its behavior to Gz and other stimuli which produce mechanical effects on the exoskeleton; (3) Not only is the cardiac response useful but it is now understood to be an integral part of the system which compensates for the consequences of gravity in the spider (an hydraulic leg extension); and (4) a theoretical model was proposed in which a mechanical amplifier, the leg lever, converts a weak force (at the tarsus) to a strong force (at the patella), capable of compressing the exoskeleton and consequently the lyriform receptor.

  20. Gravity monitoring of Tatun Volcanic Group activities and inference for underground fluid circulations

    NASA Astrophysics Data System (ADS)

    Mouyen, Maxime; Chao, Benjamin Fong; Hwang, Cheinway; Hsieh, Wen-Chi

    2016-12-01

    The Tatun Volcano Group (TVG), located on the northern coast of Taiwan adjacent to the city of Taipei, experiences active hydrothermalism but has no historical record of volcanic eruption. Yet recent studies suggest that TVG is dormant-active rather than extinct. To monitor mass transfers and to gain further understanding of this volcanic area, gravity variations have been recorded continuously since 2012 using a superconducting gravimeter, and once every few months since 2005 using absolute gravimeters. We analyze the continuous gravity time series and propose a model that best explains the gravity variations due to local groundwater redistribution. By correcting these variations, we identify gravity changes as large as 35 μGal that occurred concomitantly to fluid pressure-induced earthquakes and changes in the gas composition at Dayoukeng, one of TVG's fumaroles, over 2005-2007. We examine several fluid movements that can match the gravity observations, yet too few additional constraints exist to favor any of them. In particular, no significant ground displacements are observed when these gravity variations occurred. On the other hand, the model of gravity changes due to local groundwater redistribution can be routinely computed and removed from the ongoing time gravity measurements in order to quickly identify any unusual mass transfer occurring beneath TVG.

  1. Gravity monitoring of Tatun Volcanic Group activities and inference for underground fluid circulations

    NASA Astrophysics Data System (ADS)

    Mouyen, Maxime; Chao, Benjamin; Hwang, Cheinway; Hsieh, Wen-Chi

    2017-04-01

    The Tatun Volcano Group (TVG), located on the northern coast of Taiwan adjacent to the city of Taipei, experiences active hydrothermalism but has no historical record of volcanic eruption. Yet recent studies suggest that TVG is dormant-active rather than extinct. To monitor mass transfers and to gain further understanding of this volcanic area, gravity variations have been recorded continuously since 2012 using a superconducting gravimeter, and once every few months since 2005 using absolute gravimeters. We analyze the continuous gravity time series and propose a model that best explain the gravity variations due to local groundwater redistribution. By correcting these variations, we identify gravity changes as large as 35 µGal that occurred concomitantly to fluid pressure-induced earthquakes and changes in the gas composition at Dayoukeng, one of TVG's fumaroles, over 2005-2007. We examine several fluid movements that can match the gravity observations, yet too few additional constraints exist to favor any of them. In particular, no significant ground displacements are observed when these gravity variations occurred. On the other hand, the model of gravity changes due to local groundwater redistribution can be routinely computed and removed from the ongoing time gravity measurements in order to quickly identify any unusual mass transfer occurring beneath TVG.

  2. The quest for the perfect gravity anomaly: Part 1 - New calculation standards

    USGS Publications Warehouse

    Li, X.; Hildenbrand, T.G.; Hinze, W. J.; Keller, Gordon R.; Ravat, D.; Webring, M.

    2006-01-01

    The North American gravity database together with databases from Canada, Mexico, and the United States are being revised to improve their coverage, versatility, and accuracy. An important part of this effort is revision of procedures and standards for calculating gravity anomalies taking into account our enhanced computational power, modern satellite-based positioning technology, improved terrain databases, and increased interest in more accurately defining different anomaly components. The most striking revision is the use of one single internationally accepted reference ellipsoid for the horizontal and vertical datums of gravity stations as well as for the computation of the theoretical gravity. The new standards hardly impact the interpretation of local anomalies, but do improve regional anomalies. Most importantly, such new standards can be consistently applied to gravity database compilations of nations, continents, and even the entire world. ?? 2005 Society of Exploration Geophysicists.

  3. Measurement of ground-water storage change and specific yield using the temporal-gravity method near Rillito Creek, Tucson, Arizona

    USGS Publications Warehouse

    Pool, Donald R.; Schmidt, Werner

    1997-01-01

    The temporal-gravity method was used to estimate ground-water storage change and specific -yield values at wells near Rillito Creek, Tucson, Arizona, between early December 1992 and early January 1994. The method applies Newton's Law of Gravitation to measure changes in the local gravitational field of the Earth that are caused by changes in the mass and volume of ground water. Gravity at 50 stations in a 6-square-mile area was measured repeatedly relative to gravity at two bedrock stations. Ephemeral recharge through streamflow infiltration during the winter of 1992-93 resulted in water-level rises and gravity increases near Rillito Creek as the volume of ground water in storage increased. Water levels in wells rose as much as 30 feet, and gravity increased as much as 90 microgals. Water levels declined and gravity decreased near the stream after the last major winter flow but continued to rise and increase, respectively, in downgradient areas. Water levels and gravity relative to bedrock were measured at 10 wells. Good linear correlations between water levels and gravity values at five wells nearest the stream allowed for the estimation of specific-yield values for corresponding stratigraphic units assuming the mass change occurred in an infinite horizonal slab of uniform thickness. Specific-yield values for the stream-channel deposits at three wells ranged from 0.15 to 0.34, and correlation coefficients ranged from 0.81 to 0.99. Specific-yield values for the Fort Lowell Formation at three wells ranged from 0.07 to 0.18, and correlation coefficients ranged from 0.82 to 0.93. Specific-yield values were not calculated for the five wells farthest from the stream because of insufficient water-level and gravity change or poor correlations between water level and gravity. Poor correlations between water levels and gravity resulted from ground-water storage change in perched aquifers and in the unsaturated zone near ephemeral streams. Seasonal distributions of ground

  4. Study on relationship between evolution of regional gravity field and seismic hazard

    NASA Astrophysics Data System (ADS)

    Li, W.; Xu, C.; Shen, C.

    2017-12-01

    The lack of anomalous signal is a big issue for the study of geophysics using historical geodesy observations, which is a relatively new area of earth gravimetry application in seismology. Hence the use of the gravity anomaly (GA) derived from either a global geopotential model (GGM) or a regional gravity reanalysis (Ground Gravity Survey, GGS) becomes an important alternative solution. In this study, the GGS at 186 points for the period of 2010 2014 in the Sichuan-Yunnan region (SYR) stations are analyzed. To study the temporal and spatial distribution characteristics of regional gravity filed (RGF) and its evolution mechanism. Taking the geological and geophysical data as constraints. From the GGM expanded up to degree 360, GA were obtained after gravity reduction, especially removing the reference field. The dynamically evolutional characteristics of gravity field are closely relative to fault activity. The gravity changes with time about 5 years at LongMenShan fault (LMSF) have a slop of -12.83±2.9 μGal/a, indicating that LMSF has an uplift. To test the signal extraction algorithm in some geodynamic processes, GA from the SYR were inverted and it was also imposed as a priori information. Fortunately, some significant gravity variation have been detected at some stations in the thrust fault before and after four earthquakes, in which typical anomalies (earthquake precursor, EP) were positive GA variation near the epicenter and the occurrence of a high-gravity-gradient zone across the epicenter prior to the Lushan earthquake (Ms 7.0). The repeated observation results during about 5 years indicate that no significant gravity changes related to other geodynamical events were observed in most observation epochs. In addition, the mechanism of gravity changes at Lushan was also explored. We calculated the gravity change rates based on the model of Songpan-Ganze block (SGB) to Sichuan basin (SCB). And the changes is in good agreement with observed one, indicating

  5. Measurements of aquifer-storage change and specific yield using gravity surveys

    USGS Publications Warehouse

    Pool, D.R.; Eychaner, J.H.

    1995-01-01

    Pinal Creek is an intermittent stream that drains a 200-square-mile alluvial basin in central Arizona. Large changes in water levels and aquifer storage occur in an alluvial aquifer near the stream in response to periodic recharge and ground-water withdrawals. Outflow components of the ground-water budget and hydraulic properties of the alluvium are well-defined by field measurements; however, data are insufficient to adequately describe recharge, aquifer-storage change, and specific-yield values. An investigation was begun to assess the utility of temporal-gravity surveys to directly measure aquifer-storage change and estimate values of specific yield.The temporal-gravity surveys measured changes in the differences in gravity between two reference stations on bedrock and six stations at wells; changes are caused by variations in aquifer storage. Specific yield was estimated by dividing storage change by water-level change. Four surveys were done between February 21, 1991, and March 31, 1993. Gravity increased as much as 158 microGal ± 1 to 6 microGal, and water levels rose as much as 58 feet. Average specific yield at wells ranged from 0.16 to 0.21, and variations in specific yield with depth correlate with lithologic variations. Results indicate that temporal-gravity surveys can be used to estimate aquifer-storage change and specific yield of water-table aquifers where significant variations in water levels occur. Direct measurement of aquifer-storage change can eliminate a major unknown from the ground-water budget of arid basins and improve residual estimates of recharge.

  6. A lunar space station

    NASA Technical Reports Server (NTRS)

    Trinh, LU; Merrow, Mark; Coons, Russ; Iezzi, Gabrielle; Palarz, Howard M.; Nguyen, Marc H.; Spitzer, Mike; Cubbage, Sam

    1989-01-01

    A concept for a space station to be placed in low lunar orbit in support of the eventual establishment of a permanent moon base is proposed. This space station would have several functions: (1) a complete support facility for the maintenance of the permanent moon base and its population; (2) an orbital docking area to facilitate the ferrying of materials and personnel to and from Earth; (3) a zero gravity factory using lunar raw materials to grow superior GaAs crystals for use in semiconductors and mass produce inexpensive fiber glass; and (4) a space garden for the benefit of the air food cycles. The mission scenario, design requirements, and technology needs and developments are included as part of the proposal.

  7. International Space Station (ISS)

    NASA Image and Video Library

    1997-06-01

    This Boeing photograph shows the Node 1, Unity module, Flight Article (at right) and the U.S. Laboratory module, Destiny, Flight Article for the International Space Station (ISS) being manufactured in the High Bay Clean Room of the Space Station Manufacturing Facility at the Marshall Space Flight Center. The Node 1, or Unity, serves as a cornecting passageway to Space Station modules. The U.S. built Unity module was launched aboard the orbiter Endeavour (STS-88 mission) on December 4, 1998 and connected to the Zarya, the Russian-built Functional Energy Block (FGB). The U.S. Laboratory (Destiny) module is the centerpiece of the ISS, where science experiments will be performed in the near-zero gravity of space. The U.S. Laboratory/Destiny was launched aboard the orbiter Atlantis (STS-98 mission) on February 7, 2001. The ISS is a multidisciplinary laboratory, technology test bed, and observatory that will provide unprecedented undertakings in scientific, technological, and international experimentation.

  8. Simulated building energy demand biases resulting from the use of representative weather stations

    DOE PAGES

    Burleyson, Casey D.; Voisin, Nathalie; Taylor, Z. Todd; ...

    2017-11-06

    Numerical building models are typically forced with weather data from a limited number of “representative cities” or weather stations representing different climate regions. The use of representative weather stations reduces computational costs, but often fails to capture spatial heterogeneity in weather that may be important for simulations aimed at understanding how building stocks respond to a changing climate. Here, we quantify the potential reduction in temperature and load biases from using an increasing number of weather stations over the western U.S. Our novel approach is based on deriving temperature and load time series using incrementally more weather stations, ranging frommore » 8 to roughly 150, to evaluate the ability to capture weather patterns across different seasons. Using 8 stations across the western U.S., one from each IECC climate zone, results in an average absolute summertime temperature bias of ~4.0 °C with respect to a high-resolution gridded dataset. The mean absolute bias drops to ~1.5 °C using all available weather stations. Temperature biases of this magnitude could translate to absolute summertime mean simulated load biases as high as 13.5%. Increasing the size of the domain over which biases are calculated reduces their magnitude as positive and negative biases may cancel out. Using 8 representative weather stations can lead to a 20–40% bias of peak building loads during both summer and winter, a significant error for capacity expansion planners who may use these types of simulations. Using weather stations close to population centers reduces both mean and peak load biases. Our approach could be used by others designing aggregate building simulations to understand the sensitivity to their choice of weather stations used to drive the models.« less

  9. Simulated building energy demand biases resulting from the use of representative weather stations

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Burleyson, Casey D.; Voisin, Nathalie; Taylor, Z. Todd

    Numerical building models are typically forced with weather data from a limited number of “representative cities” or weather stations representing different climate regions. The use of representative weather stations reduces computational costs, but often fails to capture spatial heterogeneity in weather that may be important for simulations aimed at understanding how building stocks respond to a changing climate. Here, we quantify the potential reduction in temperature and load biases from using an increasing number of weather stations over the western U.S. Our novel approach is based on deriving temperature and load time series using incrementally more weather stations, ranging frommore » 8 to roughly 150, to evaluate the ability to capture weather patterns across different seasons. Using 8 stations across the western U.S., one from each IECC climate zone, results in an average absolute summertime temperature bias of ~4.0 °C with respect to a high-resolution gridded dataset. The mean absolute bias drops to ~1.5 °C using all available weather stations. Temperature biases of this magnitude could translate to absolute summertime mean simulated load biases as high as 13.5%. Increasing the size of the domain over which biases are calculated reduces their magnitude as positive and negative biases may cancel out. Using 8 representative weather stations can lead to a 20–40% bias of peak building loads during both summer and winter, a significant error for capacity expansion planners who may use these types of simulations. Using weather stations close to population centers reduces both mean and peak load biases. Our approach could be used by others designing aggregate building simulations to understand the sensitivity to their choice of weather stations used to drive the models.« less

  10. A climatology of gravity wave parameters based on satellite limb soundings

    NASA Astrophysics Data System (ADS)

    Ern, Manfred; Trinh, Quang Thai; Preusse, Peter; Riese, Martin

    2017-04-01

    Gravity waves are one of the main drivers of atmospheric dynamics. The resolution of most global circulation models (GCMs) and chemistry climate models (CCMs), however, is too coarse to properly resolve the small scales of gravity waves. Horizontal scales of gravity waves are in the range of tens to a few thousand kilometers. Gravity wave source processes involve even smaller scales. Therefore GCMs/CCMs usually parametrize the effect of gravity waves on the global circulation. These parametrizations are very simplified, and comparisons with global observations of gravity waves are needed for an improvement of parametrizations and an alleviation of model biases. In our study, we present a global data set of gravity wave distributions observed in the stratosphere and the mesosphere by the infrared limb sounding satellite instruments High Resolution Dynamics Limb Sounder (HIRDLS) and Sounding of the Atmosphere using Broadband Emission Radiometry (SABER). We provide various gravity wave parameters (for example, gravity variances, potential energies and absolute momentum fluxes). This comprehensive climatological data set can serve for comparison with other instruments (ground based, airborne, or other satellite instruments), as well as for comparison with gravity wave distributions, both resolved and parametrized, in GCMs and CCMs. The purpose of providing various different parameters is to make our data set useful for a large number of potential users and to overcome limitations of other observation techniques, or of models, that may be able to provide only one of those parameters. We present a climatology of typical average global distributions and of zonal averages, as well as their natural range of variations. In addition, we discuss seasonal variations of the global distribution of gravity waves, as well as limitations of our method of deriving gravity wave parameters from satellite data.

  11. Absolute geostrophic currents over the SR02 section south of Africa in December 2009

    NASA Astrophysics Data System (ADS)

    Tarakanov, Roman

    2017-04-01

    The structure of the absolute geostrophic currents is investigated on the basis of CTD-, SADCP- and LADCP-data over the hydrographic section occupied south of Africa from the Good Hope Cape to 57° S along the Prime Meridian, and on the basis of satellite data on absolute dynamic topography (ADT) produced by Ssalto/Duacs and distributed by Aviso, with a support from Cnes (http://www.aviso.altimetry.fr/duacs/). Thus the section crossed the subtropical zone (at the junction of the subtropical gyres of the Indian and Atlantic oceans), the Antarctic Circumpolar Current (ACC) and terminated at the northern periphery of the Weddell Gyre. A total of 87 stations were occupied here with CTD-, and LADCP-profiling in the entire water column. The distance between stations was 20 nautical miles. Absolute geostrophic currents were calculated between each pair of CTD-stations with barotropic correction based on two methods: by SADCP data and by ADT at these stations. The subtropical part of the section crossed a large segment of the Agulhas meander, already separated from the current and disintegrating into individual eddies. In addition, smaller formed cyclones and anticyclones of the Agulhas Current were also observed in this zone. These structural elements of the upper layer of the ocean currents do not penetrate deeper than 1000-1500 m. Oppositely directed barotropic currents with velocities up to 30 cm/s were observed below these depths extending to the ocean bottom. Such large velocities agree well with the data of the bottom tracking of Lowered ADCP. Only these data were the reliable results of LADCP measurements because of the high transparency of the deep waters of the subtropical zone. The total transport of absolute geostrophic currents in the section is estimated as 144 and 179 Sv to the east, based on the SADCP and ADT barotropic correction, respectively. A transport of 4 (2) Sv to the east was observed on the northern periphery of the Weddell Gyre, 187 (182) Sv to

  12. Principal facts for gravity data collected in the southern Albuquerque Basin area and a regional compilation, central New Mexico

    USGS Publications Warehouse

    Gillespie, Cindy L.; Grauch, V.J.S.; Oshetski, Kim; Keller, Gordon R.

    2000-01-01

    Principal facts for 156 new gravity stations in the southern Albuquerque basin are presented. These data fill a gap in existing data coverage. The compilation of the new data and two existing data sets into a regional data set of 5562 stations that cover the Albuquerque basin and vicinity is also described. Bouguer anomaly and isostatic residual gravity data for this regional compilation are available in digital form from ftp://greenwood.cr.usgs.gov/pub/openfile- reports/ofr-00-490.

  13. Evaluation of absorption cycle for space station environmental control system application

    NASA Technical Reports Server (NTRS)

    Sims, W. H.; Oneill, M. J.; Reid, H. C.; Bisenius, P. M.

    1972-01-01

    The study to evaluate an absorption cycle refrigeration system to provide environmental control for the space stations is reported. A zero-gravity liquid/vapor separator was designed and tested. The results were used to design a light-weight, efficient generator for the absorption refrigeration system. It is concluded that absorption cycle refrigeration is feasible for providing space station environmental control.

  14. Preliminary OARE absolute acceleration measurements on STS-50

    NASA Technical Reports Server (NTRS)

    Blanchard, Robert C.; Nicholson, John Y.; Ritter, James

    1993-01-01

    On-orbit Orbital Acceleration Research Experiment (OARE) data on STS-50 was examined in detail during a 2-day time period. Absolute acceleration levels were derived at the OARE location, the orbiter center-of-gravity, and at the STS-50 spacelab Crystal Growth Facility. The tri-axial OARE raw acceleration measurements (i.e., telemetered data) during the interval were filtered using a sliding trimmed mean filter in order to remove large acceleration spikes (e.g., thrusters) and reduce the noise. Twelve OARE measured biases in each acceleration channel during the 2-day interval were analyzed and applied to the filtered data. Similarly, the in situ measured x-axis scale factors in the sensor's most sensitive range were also analyzed and applied to the data. Due to equipment problem(s) on this flight, both y- and z- axis sensitive range scale factors were determined in a separate process (using the OARE maneuver data) and subsequently applied to the data. All known significant low-frequency corrections at the OARE location (i.e., both vertical and horizontal gravity-gradient, and rotational effects) were removed from the filtered data in order to produce the acceleration components at the orbiter's center-of-gravity, which are the aerodynamic signals along each body axes. Results indicate that there is a force of unknown origin being applied to the Orbiter in addition to the aerodynamic forces. The OARE instrument and all known gravitational and electromagnetic forces were reexamined, but none produce the observed effect. Thus, it is tentatively concluded that the Orbiter is creating the environment observed.

  15. Estimating the Earth's gravity field using a multi-satellite SLR solution

    NASA Astrophysics Data System (ADS)

    Bloßfeld, Mathis; Stefka, Vojtech; Müller, Horst; Gerstl, Michael

    2013-04-01

    Satellite Laser Ranging (SLR) is the unique technique to determine station coordinates, Earth Orientation Parameter (EOP) and Stokes coefficients of the Earth's gravity field in one common adjustment. These parameters form the so called "three pillars" (Plag & Pearlman, 2009) of the Global Geodetic Observing System (GGOS). In its function as official analysis center of the International Laser Ranging Service (ILRS), DGFI is developing and maintaining software to process SLR observations called "DGFI Orbit and Geodetic parameter estimation Software" (DOGS). The software is used to analyze SLR observations and to compute multi-satellite solutions. To take benefit of different orbit performances (e.g. inclination and altitude), a solution using ten different spherical satellites (ETALON1/2, LAGEOS1/2, STELLA, STARLETTE, AJISAI, LARETS, LARES, BLITS) covering 12 years of observations is computed. The satellites are relatively weighted using a variance component estimation (VCE). The obtained weights are analyzed w.r.t. the potential of the satellite to monitor changes in the Earths geometry, rotation and gravity field. The estimated parameters (station coordinates and EOP) are validated w.r.t. official time series of the IERS. The obtained Stokes coefficients are compared to recent gravity field solutions and discussed in detail.

  16. Quasi-12 h inertia-gravity waves in the lower mesosphere observed by the PANSY radar at Syowa Station (39.6° E, 69.0° S)

    NASA Astrophysics Data System (ADS)

    Shibuya, Ryosuke; Sato, Kaoru; Tsutsumi, Masaki; Sato, Toru; Tomikawa, Yoshihiro; Nishimura, Koji; Kohma, Masashi

    2017-05-01

    The first observations made by a complete PANSY radar system (Program of the Antarctic Syowa MST/IS Radar) installed at Syowa Station (39.6° E, 69.0° S) were successfully performed from 16 to 24 March 2015. Over this period, quasi-half-day period (12 h) disturbances in the lower mesosphere at heights of 70 to 80 km were observed. Estimated vertical wavelengths, wave periods and vertical phase velocities of the disturbances were approximately 13.7 km, 12.3 h and -0.3 m s-1, respectively. Under the working hypothesis that such disturbances are attributable to inertia-gravity waves, wave parameters are estimated using a hodograph analysis. The estimated horizontal wavelengths are longer than 1100 km, and the wavenumber vectors tend to point northeastward or southwestward. Using the nonhydrostatic numerical model with a model top of 87 km, quasi-12 h disturbances in the mesosphere were successfully simulated. We show that quasi-12 h disturbances are due to wave-like disturbances with horizontal wavelengths longer than 1400 km and are not due to semidiurnal migrating tides. Wave parameters, such as horizontal wavelengths, vertical wavelengths and wave periods, simulated by the model agree well with those estimated by the PANSY radar observations under the abovementioned assumption. The parameters of the simulated waves are consistent with the dispersion relationship of the inertia-gravity wave. These results indicate that the quasi-12 h disturbances observed by the PANSY radar are attributable to large-scale inertia-gravity waves. By examining a residual of the nonlinear balance equation, it is inferred that the inertia-gravity waves are likely generated by the spontaneous radiation mechanism of two different jet streams. One is the midlatitude tropospheric jet around the tropopause while the other is the polar night jet. Large vertical fluxes of zonal and meridional momentum associated with large-scale inertia-gravity waves are distributed across a slanted region

  17. Space Station tethered refueling facility operations

    NASA Technical Reports Server (NTRS)

    Kiefel, E. R.; Rudolph, L. K.; Fester, D. A.

    1986-01-01

    The space-based orbital transfer vehicle will require a large cryogenic fuel storage facility at the Space Station. An alternative to fuel storage onboard the Space Station, is on a tethered orbital refueling facility (TORF) which is separated from the Space Station by a sufficient distance to induce a gravity gradient to settle the propellants. Facility operations are a major concern associated with a tethered LO2/LH2 storage depot. A study was carried out to analyze these operations so as to identify the preferred TORF deployment direction (up or down) and whether the TORF should be permanently or intermittently deployed. The analyses considered safety, contamination, rendezvous, servicing, transportation rate, communication, and viewing. An upwardly, intermittently deployed facility is the preferred configuration for a tethered cryogenic fuel storage.

  18. Testing Gravity via Lunar Laser Ranging: Maximizing Data Quality

    NASA Astrophysics Data System (ADS)

    Murphy, Thomas

    Apache Observatory and from a high-quality Global Positioning System (GPS) station 2.5 km away, will greatly improve our understanding of the instantaneous location of the Observatory with respect to the Earth’s center of mass (needed for the gravitational tests) by exposing subtle Earth dynamics that must be incorporated into the model. In addition to dramatic improvements in the classical gravitational tests listed above, APOLLO will permit exploration of new ideas in physics relating to dark energy, extra dimensions, and violations of Lorentz Invariance. This proposal will have two thrusts: to continue acquiring APOLLO data, thereby probing longer-period terms in the lunar orbit; and to design and construct an absolute calibration system that can either verify APOLLO data accuracy and stability or expose elements in need of attention. APOLLO has been effective at public outreach and education not only by direct involvement with students and underrepresented groups, but also via news articles, magazine articles, radio interviews, and appearances on popular television shows. This level of media attention should continue into the future, given the appealing combination of tests of Einstein's gravity, the legendary lunar landings, and remarkable technology.

  19. The ANGWIN Antarctic Research Program: First Results on Coordinated Trans-Antarctic Gravity Wave Measurements

    NASA Astrophysics Data System (ADS)

    Taylor, M. J.; Pautet, P. D.; Zhao, Y.; Nakamura, T.; Ejiri, M. K.; Murphy, D. J.; Moffat-Griffin, T.; Kavanagh, A. J.; Takahashi, H.; Wrasse, C. M.

    2014-12-01

    ANGWIN (ANrctic Gravity Wave Instrument Network) is a new "scientist driven" research program designed to develop and utilize a network of Antarctic atmospheric gravity wave observatories, operated by different nations working together in a spirit of close scientific collaboration. Our research plan has brought together colleagues from several international institutions, all with a common goal to better understand the large "continental-scale" characteristics and impacts of gravity waves on the Mesosphere and Lower Thermosphere (MLT) environment over Antarctica. ANGWIN combines complementary measurements obtained using new and existing aeronomy instrumentation with new modeling capabilities. To date, our activities have focused on developing coordinated airglow image data of gravity waves in the MLT region at the following sites: McMurdo (US), Syowa (Japan), Davis (Australia), Halley (UK), Rothera (UK), and Comandante Ferraz (Brazil). These are all well-established international research stations that are uniformly distributed around the continental perimeter, and together with ongoing measurements at South Pole Station they provide unprecedented coverage of the Antarctic gravity wave field and its variability during the extended polar winter season. This presentation introduces the ANGWIN program and research goals, and presents first results on trans-Antarctic wave propagation using coordinated measurements during the winter season 2011. We also discuss future plans for the development of this exciting program for Antarctic research.

  20. Search for Earthquake-Induced Prompt Gravity Signals in Gravimetric Data: Data Analysis and a New Observation Model

    NASA Astrophysics Data System (ADS)

    Kimura, M.; Kame, N.; Watada, S.; Ohtani, M.; Araya, A.; Imanishi, Y.; Ando, M.; Kunugi, T.

    2017-12-01

    Seismic waves radiated from an earthquake rupture induces density perturbations of the medium, which in turn generates prompt gravity changes at all distances before the arrival of seismic waves. Detection of the gravity signal before the seismic one is a challenge in seismology. In this study, we searched for the prompt gravity changes from the 2011 Tohoku-Oki earthquake in data recorded by gravimeters, seismometers, and tiltmeters. Predicted changes from the currently used simplified model were not identified using band-pass filtering and multi-station stacking even though sufficient signal-to-noise ratios were achieved. Our data analysis raised discrepancy between the data and the theoretical model. To interpret the absence of signals in the data, we investigated the effect of self-gravity deformation on the measurement of gravitational acceleration, which has been ignored in the existing theory. We analytically calculated the displacement of the observation station induced by the prompt gravity changes in an infinite homogeneous medium, and showed that before the arrival of P waves each point in the medium moves at an acceleration identical to the applied gravity change, i.e., free-falls. As a result of the opposite inertial force, gravity sensors attached to the medium lose their sensitivity to the prompt gravity changes. This new observation model incorporated with the self-gravity effect explains the absence of such prompt signals in the acceleration data. We have shown the negative observability in acceleration, but there remains a possibility of detection of its spatial gradients or spatial strain. For a future detection experiment, we derived an analytical expression of the theoretical gravity gradients from a general seismic source described as a moment tensor.

  1. Improvement of the Earth's gravity field from terrestrial and satellite data

    NASA Technical Reports Server (NTRS)

    1987-01-01

    The terrestrial gravity data base was updated. Studies related to the Geopotential Research Mission (GRM) have primarily considered the local recovery of gravity anomalies on the surface of the Earth based on satellite to satellite tracking or gradiometer data. A simulation study was used to estimate the accuracy of 1 degree-mean anomalies which could be recovered from the GRM data. Numerous procedures were developed for the intent of performing computations at the laser stations in the SL6 system to improve geoid undulation calculations.

  2. Autonomous momentum management for space station, exhibit A

    NASA Technical Reports Server (NTRS)

    Hahn, E.

    1984-01-01

    The report discusses momentum management for the CDG Planar Space Platform. The external torques on the Space Station are assumed to be gravity gradient and aerodynamic with both having bias and cyclic terms. The integrals of the cyclic torques are the cyclic momenti which will be stored in the momentum storage actuator. Various techniques to counteract the bias torques and center the cyclic momentum were investigated including gravity gradient desaturation by adjusting vehicle attitude, aerodynamic desaturation using solar panels and radiators and the deployment of flat plates at the end of long booms generating aerodynamic torques.

  3. Space Station Freedom as an engineering experiment station: An overview

    NASA Technical Reports Server (NTRS)

    Rose, M. Frank

    1992-01-01

    In this presentation, the premise that Space Station Freedom has great utility as an engineering experiment station will be explored. There are several modes in which it can be used for this purpose. The most obvious are space qualification, process development, in space satellite repair, and materials engineering. The range of engineering experiments which can be done at Space Station Freedom run the gamut from small process oriented experiments to full exploratory development models. A sampling of typical engineering experiments are discussed in this session. First and foremost, Space Station Freedom is an elaborate experiment itself, which, if properly instrumented, will provide engineering guidelines for even larger structures which must surely be built if humankind is truly 'outward bound.' Secondly, there is the test, evaluation and space qualification of advanced electric thruster concepts, advanced power technology and protective coatings which must of necessity be tested in the vacuum of space. The current approach to testing these technologies is to do exhaustive laboratory simulation followed by shuttle or unmanned flights. Third, the advanced development models of life support systems intended for future space stations, manned mars missions, and lunar colonies can be tested for operation in a low gravity environment. Fourth, it will be necessary to develop new protective coatings, establish construction techniques, evaluate new materials to be used in the upgrading and repair of Space Station Freedom. Finally, the industrial sector, if it is ever to build facilities for the production of commercial products, must have all the engineering aspects of the process evaluated in space prior to a commitment to such a facility.

  4. Device for mass measurement under zero-gravity conditions.

    PubMed

    Sarychev, V A; Sazonov, V V; Zlatorunsky, A S; Khlopina, S F; Egorov, A D; Somov, V I

    1980-06-01

    The problem considered in this paper is the investigation of the properties of a mass-meter, i.e. the device for determining the mass of cosmonaut's body under zero-gravity conditions. The estimates of accuracy of mass measurement by this device are given, and the results of measuring the masses of cosmonauts' bodies on the Salyut 5 and 6 orbital stations are presented.

  5. Gravity Survey on the Glass Buttes Geothermal Exploration Project Lake County, Oregon

    DOE Data Explorer

    John Akerley

    2011-10-12

    This report covers data acquisition, instrumentation and processing of a gravity survey performed on the Glass Buttes Geothermal Exploration Project, located in Lake County, Oregon for ORMAT Technologies Inc. The survey was conducted during 21 June 2010 to 26 June 2010. The survey area is located in T23S, R21-23E and lies within the Glass Buttes, Hat Butte, and Potato Lake, Oregon 1:24,000 topographic sheets. A total of 180 gravity stations were acquired along five profile lines.

  6. Gravity survey of Dixie Valley, west-central Nevada

    USGS Publications Warehouse

    Schaefer, Donald H.

    1983-01-01

    Dixie Valley, a northeast-trending structural trough typical of valleys in the Basin and Range Province, is filled with a maximum of about 10,000 feet of alluvial and lacustrine deposits , as estimated from residual-gravity measurements obtained in this study. On the basis of gravity measurements at 300 stations on nine east-west profiles, the gravity residuals reach a maximum of 30 milligals near the south-central part of the valley. Results from a three-dimensional inversion model indicate that the central depression of the valley is offset to the west of the geographic axis. This offset is probably due to major faulting along the west side of the valley adjacent to the Stillwater Range. Comparison of depths to bedrock obtained during this study and depths obtained from a previous seismic-refraction study indicates a reasonably good correlation. A heterogeneous distribution of densities within the valley-fill deposits would account for differing depths determined by the two methods. (USGS)

  7. Detailed gravity survey to help seismic microzonation: Mapping the thickness of unconsolidated deposits in Ottawa, Canada

    NASA Astrophysics Data System (ADS)

    Lamontagne, M.; Thomas, M.; Silliker, J.; Jobin, D.

    2011-11-01

    In this study, measurements of gravity were made to map and model the thickness of Quaternary deposits (sand and clay) overlying Ordovician limestones in a suburb of Ottawa (Orléans, Ontario). Because ground motion amplification is partly related to the thickness of unconsolidated deposits, this work helps refine the assessment of the earthquake damage potential of the area. It also helps the mapping of clay basins, which can locally exceed 100 m in thickness, where ground motion amplification can occur. Previous work, including well log data and seismic methods, have yielded a wealth of information on near-surface geology in Orléans, thereby providing the necessary constraints to test the applicability of gravity modeling in other locations where other methods cannot always be used. Some 104 gravity stations were occupied in an 8 × 12 km test area in the Orléans. Stations were accurately located with differential GPS that provided centimetric accuracy in elevation. Densities of the unconsolidated Quaternary deposits (Champlain Sea clay) determined on core samples and densities determined on limestone samples from outcrops were used to constrain models of the clay layer overlying the higher density bedrock formations (limestone). The gravity anomaly map delineates areas where clay basins attain > 100 m depth. Assuming a realistic density for the Champlain Sea clays (1.9-2.1 g/cm 3), the thickness over the higher density bedrock formations (Ordovician carbonate rocks) was modeled and compared with well logs and two seismic reflection profiles. The models match quite well with the information determined from well logs and seismic methods. It was found that gravity and the thickness of unconsolidated deposits are correlated but the uncertainties in both data sets preclude the definition of a direct correlation between the two. We propose that gravity measurements at a local scale be used as an inexpensive means of mapping the thickness of unconsolidated deposits

  8. GRACE Solutions for the Gravity Field over Central Europe Compared to the Surface Field as Recorded by the GGP Network.

    NASA Astrophysics Data System (ADS)

    Crossley, D. J.; de Linage, C.; Hinderer, J.; Boy, J.

    2007-12-01

    As the number of different solutions from the GRACE satellite gravity project evolves, we can make more meaningful comparisons between the satellite-derived field and the surface field as recorded by superconducting gravimeters. On the GRACE side, we use CSR Level 2 products RL01 and the recent RL04 solutions, GFZ RL04 solutions, and the CNES/GRGS 10-day solutions, all for the time periods these are available. On the GGP side, we take advantage of the 10 years of SG data since July 1997 from 6-8 ground stations in Europe, allowing for the change in the network configuration as stations begin and end recording. Only data since 2002 can be compared directly to GRACE. Our primary measure of variability is the first principal component of the EOF analysis of all the fields. Unsurprisingly, the seasonal components for all the comparisons are similar in phase, but different in amplitude, to the predictions from a global hydrology model (GLDAS), provided allowance is made for the location of the SG stations above or below the soil moisture horizon that controls the gravity signature. We use detailed modeling at the Strasbourg station, as well as published results for Moxa and Membach, to confirm the gravity effect of hydrology. Good agreement is found between the GGP and the CNES/GRGS 10-day solutions, indicating the higher temporal resolution of this satellite solution is valid for our limited geographical area. We also synthesize the gravity field over the sub-group of GGP stations in N.E. Asia to see how the GRACE variability compares to that for the European array and to assess future ground validation using new GGP stations in that part of the world.

  9. Dark Matter Decays from Nonminimal Coupling to Gravity.

    PubMed

    Catà, Oscar; Ibarra, Alejandro; Ingenhütt, Sebastian

    2016-07-08

    We consider the standard model extended with a dark matter particle in curved spacetime, motivated by the fact that the only current evidence for dark matter is through its gravitational interactions, and we investigate the impact on the dark matter stability of terms in the Lagrangian linear in the dark matter field and proportional to the Ricci scalar. We show that this "gravity portal" induces decay even if the dark matter particle only has gravitational interactions, and that the decay branching ratios into standard model particles only depend on one free parameter: the dark matter mass. We study in detail the case of a singlet scalar as a dark matter candidate, which is assumed to be absolutely stable in flat spacetime due to a discrete Z_{2} symmetry, but which may decay in curved spacetimes due to a Z_{2}-breaking nonminimal coupling to gravity. We calculate the dark matter decay widths and we set conservative limits on the nonminimal coupling parameter from experiments. The limits are very stringent and suggest that there must exist an additional mechanism protecting the singlet scalar from decaying via this gravity portal.

  10. Soldering Tested in Reduced Gravity

    NASA Technical Reports Server (NTRS)

    Struk, Peter M.; Pettegrew, Richard D.; Watson, J. Kevin; Down, Robert S.; Haylett, Daniel R.

    2005-01-01

    Whether used occasionally for contingency repair or routinely in nominal repair operations, soldering will become increasingly important to the success of future long-duration human space missions. As a result, it will be critical to have a thorough understanding of the service characteristics of solder joints produced in reduced-gravity environments. The National Center for Space Exploration Research (via the Research for Design program), the NASA Glenn Research Center, and the NASA Johnson Space Center are conducting an experimental program to explore the influence of reduced gravity environments on the soldering process. Solder joint characteristics that are being considered include solder fillet geometry, porosity, and microstructural features. Both through-hole (see the drawing and image on the preceding figure) and surface-mounted devices are being investigated. This effort (the low-gravity portion being conducted on NASA s KC-135 research aircraft) uses the soldering hardware currently available on the International Space Station. The experiment involves manual soldering by a contingent of test operators, including both highly skilled technicians and less skilled individuals to provide a skill mix that might be encountered in space mission crews. The experiment uses both flux-cored solder and solid-core solder with an externally applied flux. Other experimental parameters include the type of flux, gravitational level (nominally zero,

  11. Life sciences biomedical research planning for Space Station

    NASA Technical Reports Server (NTRS)

    Primeaux, Gary R.; Michaud, Roger; Miller, Ladonna; Searcy, Jim; Dickey, Bernistine

    1987-01-01

    The Biomedical Research Project (BmRP), a major component of the NASA Life Sciences Space Station Program, incorporates a laboratory for the study of the effects of microgravity on the human body, and the development of techniques capable of modifying or counteracting these effects. Attention is presently given to a representative scenario of BmRP investigations and associated engineering analyses, together with an account of the evolutionary process by which the scenarios and the Space Station design requirements they entail are identified. Attention is given to a tether-implemented 'variable gravity centrifuge'.

  12. Feeling Gravity's Pull: Gravity Modeling. The Gravity Field of Mars

    NASA Technical Reports Server (NTRS)

    Lemoine, Frank; Smith, David; Rowlands, David; Zuber, Maria; Neumann, G.; Chinn, Douglas; Pavlis, D.

    2000-01-01

    Most people take the constant presence of gravitys pull for granted. However, the Earth's gravitational strength actually varies from location to location. This variation occurs because mass, which influences an object's gravitational pull, is not evenly distributed within the planet. Changes in topography, such as glacial movement, an earthquake, or a rise in the ocean level, can subtly affect the gravity field. An accurate measurement of the Earth's gravity field helps us understand the distribution of mass beneath the surface. This insight can assist us in locating petroleum, mineral deposits, ground water, and other valuable substances. Gravity mapping can also help notice or verify changes in sea surface height and other ocean characteristics. Such changes may indicate climate change from polar ice melting and other phenomena. In addition, gravity mapping can indicate how land moves under the surface after earthquakes and other plate tectonic processes. Finally, changes in the Earth's gravity field might indicate a shift in water distribution that could affect agriculture, water supplies for population centers, and long-term weather prediction. Scientists can map out the Earth's gravity field by watching satellite orbits. When a satellite shifts in vertical position, it might be passing over an area where gravity changes in strength. Gravity is only one factor that may shape a satellite's orbital path. To derive a gravity measurement from satellite movement, scientists must remove other factors that might affect a satellite's position: 1. Drag from atmospheric friction. 2. Pressure from solar radiation as it heads toward Earth and. as it is reflected off the surface of the Earth 3. Gravitational pull from the Sun, the Moon, and other planets in the Solar System. 4. The effect of tides. 5. Relativistic effects. Scientists must also correct for the satellite tracking process. For example, the tracking signal must be corrected for refraction through the

  13. Geophysical investigation using gravity data in Kinigi geothermal field, northwest Rwanda

    NASA Astrophysics Data System (ADS)

    Uwiduhaye, Jean d.'Amour; Mizunaga, Hideki; Saibi, Hakim

    2018-03-01

    A land gravity survey was carried out in the Kinigi geothermal field, Northwest Rwanda using 184 gravity stations during August and September, 2015. The aim of the gravity survey was to understand the subsurface structure and its relation to the observed surface manifestations in the study area. The complete Bouguer Gravity anomaly was produced with a reduction density of 2.4 g/cm3. Bouguer anomalies ranging from -52 to -35 mGals were observed in the study area with relatively high anomalies in the east and northwest zones while low anomalies are observed in the southwest side of the studied area. A decrease of 17 mGals is observed in the southwestern part of the study area and caused by the low-density of the Tertiary rocks. Horizontal gradient, tilt angle and analytical signal methods were applied to the observed gravity data and showed that Mubona, Mpenge and Cyabararika surface springs are structurally controlled while Rubindi spring is not. The integrated results of gravity gradient interpretation methods delineated a dominant geological structure trending in the NW-SE, which is in agreement with the regional geological trend. The results of this gravity study will help aid future geothermal exploration and development in the Kinigi geothermal field.

  14. Gravity for Detecting Caves: Airborne and Terrestrial Simulations Based on a Comprehensive Karstic Cave Benchmark

    NASA Astrophysics Data System (ADS)

    Braitenberg, Carla; Sampietro, Daniele; Pivetta, Tommaso; Zuliani, David; Barbagallo, Alfio; Fabris, Paolo; Rossi, Lorenzo; Fabbri, Julius; Mansi, Ahmed Hamdi

    2016-04-01

    Underground caves bear a natural hazard due to their possible evolution into a sink hole. Mapping of all existing caves could be useful for general civil usages as natural deposits or tourism and sports. Natural caves exist globally and are typical in karst areas. We investigate the resolution power of modern gravity campaigns to systematically detect all void caves of a minimum size in a given area. Both aerogravity and terrestrial acquisitions are considered. Positioning of the gravity station is fastest with GNSS methods the performance of which is investigated. The estimates are based on a benchmark cave of which the geometry is known precisely through a laser-scan survey. The cave is the Grotta Gigante cave in NE Italy in the classic karst. The gravity acquisition is discussed, where heights have been acquired with dual-frequency geodetic GNSS receivers and Total Station. Height acquisitions with non-geodetic low-cost receivers are shown to be useful, although the error on the gravity field is larger. The cave produces a signal of -1.5 × 10-5 m/s2, with a clear elliptic geometry. We analyze feasibility of airborne gravity acquisitions for the purpose of systematically mapping void caves. It is found that observations from fixed wing aircraft cannot resolve the caves, but observations from slower and low-flying helicopters or drones do. In order to detect the presence of caves the size of the benchmark cave, systematic terrestrial acquisitions require a density of three stations on square 500 by 500 m2 tiles. The question has a large impact on civil and environmental purposes, since it will allow planning of urban development at a safe distance from subsurface caves. The survey shows that a systematic coverage of the karst would have the benefit to recover the position of all of the greater existing void caves.

  15. Orbiting Deep Space Relay Station (ODSRS). Volume 1: Requirement determination

    NASA Technical Reports Server (NTRS)

    Hunter, J. A.

    1979-01-01

    The deep space communications requirements of the post-1985 time frame are described and the orbiting deep space relay station (ODSRS) is presented as an option for meeting these requirements. Under current conditions, the ODSRS is not yet cost competitive with Earth based stations to increase DSN telemetry performance, but has significant advantages over a ground station, and these are sufficient to maintain it as a future option. These advantages include: the ability to track a spacecraft 24 hours per day with ground stations located only in the USA; the ability to operate at higher frequencies that would be attenuated by Earth's atmosphere; and the potential for building very large structures without the constraints of Earth's gravity.

  16. International Space Station (ISS)

    NASA Image and Video Library

    1997-11-26

    This photograph shows the U.S. Laboratory Module (also called Destiny) for the International Space Station (ISS), under construction in the Space Station manufacturing facility at the Marshall Space Flight Center. The U.S. Laboratory module is the centerpiece of the ISS, where science experiments will be performed in the near-zero gravity of space. The Destiny Module was launched aboard the Space Shuttle orbiter Atlantis (STS-67 mission) on February 7, 2001. The aluminum module is 8.5 meters (28 feet) long and 4.3 meters (14 feet) in diameter. The laboratory consists of three cylindrical sections and two end cones with hatches that will be mated to other station components. A 50.9-centimeter- (20-inch-) diameter window is located on one side of the center module segment. This pressurized module is designed to accommodate pressurized payloads. It has a capacity of 24 rack locations, and payload racks will occupy 13 locations especially designed to support experiments. The ISS is a multidisciplinary laboratory, technology test bed, and observatory that will provide unprecedented undertakings in scientific, technological, and international experimentation.

  17. Gravity and isostatic anomaly maps of Greece produced

    NASA Astrophysics Data System (ADS)

    Lagios, E.; Chailas, S.; Hipkin, R. G.

    A gravity anomaly map of Greece was first compiled in the early 1970s [Makris and Stavrou, 1984] from all available gravity data collected by different Hellenic institutions. However, to compose this map the data had to be smoothed to the point that many of the smaller-wavelength gravity anomalies were lost. New work begun in 1987 has resulted in the publication of an updated map [Lagios et al., 1994] and an isostatic anomaly map derived from it.The gravity data cover the area between east longitudes 19° and 27° and north latitudes 32° and 42°, organized in files of 100-km squares and grouped in 10-km squares using UTM zone 34 coordinates. Most of the data on land come from the gravity observations of Makris and Stavrou [1984] with additional data from the Institute of Geology and Mining Exploration, the Public Oil Corporation of Greece, and Athens University. These data were checked using techniques similar to those used in compiling the gravity anomaly map of the United States, but the horizontal gradient was used as a check rather than the gravity difference. Marine data were digitized from the maps of Morelli et al. [1975a, 1975b]. All gravity anomaly values are referred to the IGSN-71 system, reduced with the standard Bouger density of 2.67 Mg/m3. We estimate the errors of the anomalies in the continental part of Greece to be ±0.9 mGal; this is expected to be smaller over fairly flat regions. For stations whose height has been determined by leveling, the error is only ±0.3 mGal. For the marine areas, the errors are about ±5 mGal [Morelli, 1990].

  18. Multi-geodetic characterization of the seasonal signal at the CERGA geodetic reference station, France

    NASA Astrophysics Data System (ADS)

    Mémin, Anthony; Viswanathan, Vishnu; Fienga, Agnes; Santamarìa-Gómez, Alvaro; Boy, Jean-Paul; Cavalié, Olivier; Deleflie, Florent; Exertier, Pierre; Bernard, Jean-Daniel; Hinderer, Jacques

    2017-04-01

    . Finally, we estimate local mass changes using the absolute gravity measurement campaigns available at the station and the global models of surface-mass change. We compute the induced station motion that we compare with the local deformation observed by InSAR and GPS.

  19. Time-lapse gravity and levelling in the sinkhole-endangered urban area of Bad Frankenhausen, Germany

    NASA Astrophysics Data System (ADS)

    Kobe, Martin; Gabriel, Gerald; Weise, Adelheid; Krawczyk, Charlotte; Vogel, Detlef

    2017-04-01

    Sinkholes, resulting from subrosion in the subsurface, can reach diameters of several hundred meters and thus pose a severe hazard for infrastructure and inhabitants in urban areas. Subrosion is the leaching of readily-soluble rocks, such as rock salt, gypsum, anhydrite and limestone by ground or meteoric water and leads to mass transport and relocation. Two scenarios of sinkhole evolution are conceivable: First, the surface subsides continuously in order to compensate for the mass loss. Second, the mass relocation leads to development of subsurface cavities. If they reach a critical size and the cover layers are not supported anymore, the surface collapses abruptly. To improve the understanding of subrosion processes and the related surface deformation a case study is conducted in Bad Frankenhausen, Germany, where subrosion leaches the Zechstein evaporates of the Permian. One part of the study is to analyse the spatiotemporal development of sinkholes by applying time-lapse observations. Therefore, we established a monitoring network consisting of 15 gravity and additional levelling points covering the main sinkhole areas in the city centre. In March 2014, the baseline survey was carried out. Since then, quarterly measurement campaigns are performed. In each campaign four different gravity meters are used to collect a statistical significant amount of data and to control the plausibility of our data. The gravity measurements are complemented by levelling surveys. The rectification of the time-lapse gravity data comprises the correction for jumps and systematic errors, as well as for well calculable influences, such as earth tides and air pressure changes. Furthermore, special interest was applied to seasonal changes of hydrological parameters such as soil moisture or groundwater level. We found the hydrological influence to be in the single digit up to the lower two-digit µGal range, depending on the season and the station. The standard deviations of the adjusted

  20. The International Gravity Field Service (IGFS): Present Day Activities And Future Plans

    NASA Astrophysics Data System (ADS)

    Barzaghi, R.; Vergos, G. S.

    2016-12-01

    IGFS is a unified "umbrella" IAG service that coordinates the servicing of the geodetic and geophysical community with gravity field related data, software and information. The combined data of the IGFS entities will include global geopotential models, terrestrial, airborne, satellite and marine gravity observations, Earth tide data, GPS/levelling data, digital models of terrain and bathymetry, as well as ocean gravity field and geoid from satellite altimetry. The IGFS structure is based on the Gravity Services, the "operating arms" of IGFS. These Services related to IGFS are: BGI (Bureau Gravimetrique International), Toulouse, France ISG (International Service for the Geoid), Politecnico di Milano, Milano, Italy IGETS (International Geodynamics and Earth Tides Service), EOST, Strasbourg, France ICGEM (International Center for Global Earth Models), GFZ, Potsdam, Germany IDEMS (International Digital Elevation Model Service), ESRI, Redlands, CA, USA The Central Bureau, hosted at the Aristotle Thessaloniki University, is in charge for all the interactions among the services and the other IAG bodies, particularly GGOS. In this respect, connections with the GGOS Bureaus of Products and Standards and of Networks and Observations have been recently strengthened in order to align the Gravity services to the GGOS standards. IGFS is also strongly involved in the most relevant projects related to the gravity field such as the establishment of the new Global Absolute Gravity Reference System and of the International Height Reference System. These projects, along with the organization of Geoid Schools devoted to methods for gravity and geoid estimate, will play a central role in the IGFS future actions in the framework of GGOS.

  1. Principal facts for a gravity survey of the Double Hot Springs Known Geothermal Resource Area, Humboldt County, Nevada

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Peterson, D.L.; Kaufmann, H.E.

    1978-01-01

    During July 1977, forty-nine gravity stations were obtained in the Double Hot Springs Known Geothermal Resource Area and vicinity, northwestern Nevada. The gravity observations were made with a Worden gravimeter having a scale factor of about 0.5 milligal per division. No terrain corrections have been applied to these data. The earth tide correction was not used in drift reduction. The Geodetic Reference System 1967 formula (International Association of Geodesy, 1967) was used to compute theoretical gravity.

  2. Vacuum/Zero Net-Gravity Application for On-Orbit TPS Tile Repair

    NASA Technical Reports Server (NTRS)

    Harvey, Gale A.; Humes, Donald H.; Siochi, Emilie J.

    2004-01-01

    The Orbiter Columbia catastrophically failed during reentry February 1, 2003. All space Shuttle flights were suspended, including logistics support for the International Space Station. NASA LaRC s Structures and Materials Competency is performing characterizations of candidate materials for on-orbit repair of orbiter Thermal Protection System (TPS) tiles to support Return-to-Flight activities led by JSC. At least ten materials properties or attributes (adhesion to damage site, thermal protection, char/ash strength, thermal expansion, blistering, flaming, mixing ease, application in vacuum and zero gravity, cure time, shelf or storage life, and short-term outgassing and foaming) of candidate materials are of interest for on-orbit repair. This paper reports application in vacuum and zero net-gravity (for viscous flow repair materials). A description of the test apparatus and preliminary results of several candidate materials are presented. The filling of damage cavities is different for some candidate repair materials in combined vacuum and zero net-gravity than in either vacuum or zero net- gravity alone.

  3. International Space Station (ISS)

    NASA Image and Video Library

    2001-02-16

    The International Space Station (ISS), with its newly attached U.S. Laboratory, Destiny, was photographed by a crew member aboard the Space Shuttle Orbiter Atlantis during a fly-around inspection after Atlantis separated from the Space Station. The Laboratory is shown in the foreground of this photograph. The American-made Destiny module is the cornerstone for space-based research aboard the orbiting platform and the centerpiece of the International Space Station (ISS), where unprecedented science experiments will be performed in the near-zero gravity of space. Destiny will also serve as the command and control center for the ISS. The aluminum module is 8.5-meters (28-feet) long and 4.3-meters (14-feet) in diameter. The laboratory consists of three cylindrical sections and two endcones with hatches that will be mated to other station components. A 50.9-centimeter (20-inch-) diameter window is located on one side of the center module segment. This pressurized module is designed to accommodate pressurized payloads. It has a capacity of 24 rack locations. Payload racks will occupy 15 locations especially designed to support experiments. The Destiny module was built by the Boeing Company under the direction of the Marshall Space Flight Center.

  4. International Space Station (ISS)

    NASA Image and Video Library

    2001-02-16

    With its new U.S. Laboratory, Destiny, contrasted over a blue and white Earth, the International Space Station (ISS) was photographed by one of the STS-98 crew members aboard the Space Shuttle Atlantis following separation of the Shuttle and Station. The Laboratory is shown at the lower right of the Station. The American-made Destiny module is the cornerstone for space-based research aboard the orbiting platform and the centerpiece of the ISS, where unprecedented science experiments will be performed in the near-zero gravity of space. Destiny will also serve as the command and control center for the ISS. The aluminum module is 8.5- meters (28-feet) long and 4.3-meters (14-feet) in diameter. The laboratory consists of three cylindrical sections and two endcones with hatches that will be mated to other station components. A 50.9-centimeter (20-inch-) diameter window is located on one side of the center module segment. This pressurized module is designed to accommodate pressurized payloads. It has a capacity of 24 rack locations. Payload racks will occupy 15 locations especially designed to support experiments. The Destiny module was built by the Boeing Company under the direction of the Marshall Space Flight Center.

  5. ORBSIM- ESTIMATING GEOPHYSICAL MODEL PARAMETERS FROM PLANETARY GRAVITY DATA

    NASA Technical Reports Server (NTRS)

    Sjogren, W. L.

    1994-01-01

    The ORBSIM program was developed for the accurate extraction of geophysical model parameters from Doppler radio tracking data acquired from orbiting planetary spacecraft. The model of the proposed planetary structure is used in a numerical integration of the spacecraft along simulated trajectories around the primary body. Using line of sight (LOS) Doppler residuals, ORBSIM applies fast and efficient modelling and optimization procedures which avoid the traditional complex dynamic reduction of data. ORBSIM produces quantitative geophysical results such as size, depth, and mass. ORBSIM has been used extensively to investigate topographic features on the Moon, Mars, and Venus. The program has proven particulary suitable for modelling gravitational anomalies and mascons. The basic observable for spacecraft-based gravity data is the Doppler frequency shift of a transponded radio signal. The time derivative of this signal carries information regarding the gravity field acting on the spacecraft in the LOS direction (the LOS direction being the path between the spacecraft and the receiving station, either Earth or another satellite). There are many dynamic factors taken into account: earth rotation, solar radiation, acceleration from planetary bodies, tracking station time and location adjustments, etc. The actual trajectories of the spacecraft are simulated using least squares fitted to conic motion. The theoretical Doppler readings from the simulated orbits are compared to actual Doppler observations and another least squares adjustment is made. ORBSIM has three modes of operation: trajectory simulation, optimization, and gravity modelling. In all cases, an initial gravity model of curved and/or flat disks, harmonics, and/or a force table are required input. ORBSIM is written in FORTRAN 77 for batch execution and has been implemented on a DEC VAX 11/780 computer operating under VMS. This program was released in 1985.

  6. Some operational aspects of a rotating advanced-technology space station for the year 2025

    NASA Technical Reports Server (NTRS)

    Queijo, M. J.; Butterfield, A. J.; Cuddihy, W. F.; King, C. B.; Stone, R. W.; Wrobel, J. R.; Garn, P. A.

    1988-01-01

    The study of an Advanced Technology Space Station which would utilize the capabilities of subsystems projected for the time frame of the years 2000 to 2025 is discussed. The study includes tradeoffs of nuclear versus solar dynamic power systems that produce power outputs of 2.5 megawatts and analyses of the dynamics of the spacecraft of which portions are rotated for artificial gravity. The design considerations for the support of a manned Mars mission from low Earth orbit are addressed. The studies extend to on-board manufacturing, internal gas composition effects, and locomotion and material transfer under artificial gravity forces. The report concludes with an assessment of technology requirements for the Advanced Technology Space Station.

  7. Preliminary Correlations of Gravity and Topography from Mars Global Surveyor

    NASA Technical Reports Server (NTRS)

    Zuber, M. T.; Tyler, G. L.; Smith, D. E.; Balmino, G. S.; Johnson, G. L.; Lemoine, F. G.; Neumann, G. A.; Phillips, R. J.; Sjogren, W. L.; Solomon, S. C.

    1999-01-01

    The Mars Global Surveyor (MGS) spacecraft is currently in a 400-km altitude polar mapping orbit and scheduled to begin global mapping of Mars in March of 1999. Doppler tracking data collected in this Gravity Calibration Orbit prior to the nominal mapping mission combined with observations from the MGS Science Phasing Orbit in Spring - Summer 1999 and the Viking and mariner 9 orbiters has led to preliminary high resolution gravity fields. Spherical harmonic expansions have been performed to degree and order 70 and are characterized by the first high spatial resolution coverage of high latitudes. Topographic mapping by the Mars Orbiter Laser Altimeter on MGS is providing measurements of the height of the martian surface with sub-meter vertical resolution and 5-30 m absolute accuracy. Data obtained during the circular mapping phase are expected to provide the first high resolution measurements of surface heights in the southern hemisphere. The combination of gravity and topography measurements provides information on the structure of the planetary interior, i.e. the rigidity and distribution of internal density. The observations can also be used to address the mechanisms of support of surface topography. Preliminary results of correlations of gravity and topography at long planetary wavelengths will be presented and the implications for internal structure will be addressed.

  8. Proposed CMG momentum management scheme for space station

    NASA Technical Reports Server (NTRS)

    Bishop, L. R.; Bishop, R. H.; Lindsay, K. L.

    1987-01-01

    A discrete control moment gyro (CMG) momentum management scheme (MMS) applicable to spacecraft with principal axes misalignments, such as the proposed NASA dual keel space station, is presented in this paper. The objective of the MMS is to minmize CMG angular momentum storage requirements for maintaining the space station near local vertical in the presence of environmental disturbances. It utilizes available environmental disturbances, namely gravity gradient torques, to minimize CMG momentum storage. The MMS is executed once per orbit and generates a commanded torque equilibrium attitude (TEA) time history which consists of a yaw, pitch and roll angle command profile. Although the algorithm is called only once per orbit to compute the TEA profile, the space station will maneuver several discrete times each orbit.

  9. A Fast Full Tensor Gravity computation algorithm for High Resolution 3D Geologic Interpretations

    NASA Astrophysics Data System (ADS)

    Jayaram, V.; Crain, K.; Keller, G. R.

    2011-12-01

    We present an algorithm to rapidly calculate the vertical gravity and full tensor gravity (FTG) values due to a 3-D geologic model. This algorithm can be implemented on single, multi-core CPU and graphical processing units (GPU) architectures. Our technique is based on the line element approximation with a constant density within each grid cell. This type of parameterization is well suited for high-resolution elevation datasets with grid size typically in the range of 1m to 30m. The large high-resolution data grids in our studies employ a pre-filtered mipmap pyramid type representation for the grid data known as the Geometry clipmap. The clipmap was first introduced by Microsoft Research in 2004 to do fly-through terrain visualization. This method caches nested rectangular extents of down-sampled data layers in the pyramid to create view-dependent calculation scheme. Together with the simple grid structure, this allows the gravity to be computed conveniently on-the-fly, or stored in a highly compressed format. Neither of these capabilities has previously been available. Our approach can perform rapid calculations on large topographies including crustal-scale models derived from complex geologic interpretations. For example, we used a 1KM Sphere model consisting of 105000 cells at 10m resolution with 100000 gravity stations. The line element approach took less than 90 seconds to compute the FTG and vertical gravity on an Intel Core i7 CPU at 3.07 GHz utilizing just its single core. Also, unlike traditional gravity computational algorithms, the line-element approach can calculate gravity effects at locations interior or exterior to the model. The only condition that must be met is the observation point cannot be located directly above the line element. Therefore, we perform a location test and then apply appropriate formulation to those data points. We will present and compare the computational performance of the traditional prism method versus the line element

  10. Principal facts for gravity data collected in South Dakota: a web site for distribution of data

    USGS Publications Warehouse

    Kucks, Robert P.; Zawislak, Ronald L.

    2001-01-01

    Principal facts for 12266 new gravity stations and 2880 stations previously released in paper form (Klasner and Kucks, 1988) for the state of South Dakota are presented. These data were contracted to fill a gap in existing data coverage for the state. Observed and Bouguer anomaly data for this regional compilation are available here in digital form.

  11. Mobile quantum gravity sensor with unprecedented stability

    NASA Astrophysics Data System (ADS)

    Leykauf, Bastian; Freier, Christian; Schkolnik, Vladimir; Krutzik, Markus; Peters, Achim

    2017-04-01

    The gravimetric atom interferometer GAIN is based on interfering ensembles of laser-cooled 87Rb atoms in a fountain setup, using stimulated Raman transitions. GAIN's rugged design allows for transports to sites of geodetic and geophysical interest while maintaining a high accuracy compatible with the best classical instruments. We compared our instrument's performance with falling corner-cube and superconducting gravimeters in two measurement campaigns at geodetic observatories in Wettzell, Germany and Onsala, Sweden. Our instrument's long-term stability of 0.5 nm/s2 is the best value for absolute gravimeters reported to date [1]. Our measured gravity value agrees with other state-of-the-art gravimeters on the 10-9 level in g, demonstrating effective control over systematics including wavefront distortions of the Raman beams [2]. By using the juggling technique [3], we are able to perform gravity measurements on two atomic clouds simultaneously. Advantages include the suppression of common mode phase noise, enabling differential phase shift extraction without the need for vibration isolation. We will present the results of our first gravity gradient measurements. [1] Freier, Hauth, Schkolnik, Leykauf, Schilling, Wziontek, Scherneck, Müller and Peters (2016). Mobile quantum gravity sensor with unprecedented stability. Journal of Physics: Conference Series, 8th Symposium on Frequency Standards and Metrology 2015, 723, 12050. [2] Schkolnik, Leykauf, Hauth, Freier and Peters (2015). The effect of wavefront aberrations in atom interferometry. Applied Physics B, 120(2), 311 - 316. [3] Legere and Gibble (1998). Quantum Scattering in a Juggling Atomic Fountain. Physical Review Letters, 81(1), 5780 - 5783.

  12. Neutral Buoyancy Simulator - Space Station

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Skylab's success proved that scientific experimentation in a low gravity environment was essential to scientific progress. A more permanent structure was needed to provide this space laboratory. President Ronald Reagan, on January 25, 1984, during his State of the Union address, claimed that the United States should exploit the new frontier of space, and directed NASA to build a permanent marned space station within a decade. The idea was that the space station would not only be used as a laboratory for the advancement of science and medicine, but would also provide a staging area for building a lunar base and manned expeditions to Mars and elsewhere in the solar system. President Reagan invited the international community to join with the United States in this endeavour. NASA and several countries moved forward with this concept. By December 1985, the first phase of the space station was well underway with the design concept for the crew compartments and laboratories. Pictured are two NASA astronauts, at Marshall Space Flight Center's (MSFC) Neutral Buoyancy Simulator (NBS), practicing construction techniques they later used to construct the space station after it was deployed.

  13. Extent of Continental Crust Thickening Derived From Gravity Profile Leading From Aden Towards the Dhala Plateau in the Yemen Trap Series

    NASA Astrophysics Data System (ADS)

    Blecha, V.

    2003-12-01

    Gravity profile trends NNW from Aden and terminates at the Dhala plateau formed by Tertiary volcanics often referred to as the Yemen Trap Series. The length of profile is 120 km. Profile consists of 366 gravity stations with average distance of 300 m between stations. The mean square error of Bouguer anomalies is 0.06 mGal. This final error includes errors of gravity and altitude measurements and error in terrain corrections. Altitudes along profile are ranging from 0 m a.s.l. in the south to 1400 m a.s.l. at the northern side of profile. In the central part of the Gulf of Aden occurs juvenile oceanic crust. Stretched continental crust is assumed on the coast. Regional gravity field decreases from +38 mGal on the coast in Aden to -126 mGal at mountains of the Dhala plateau. According to gravity modeling the decrease of 164 mGal in gravity is caused by 8 km continental crust thickening over the distance of 120 km. Regional gravity field is accompanied by local anomalies with amplitudes of tens of mGal. Sources of local anomalies are from S to N: coastal sediments (negative), Tertiary intrusions and volcanics within the Dhala graben (positive), Mesozoic sediments (negative) and Tertiary volcanics of the Dhala plateau (positive). Gravity profile is most detailed and most precise regional gravity measurement carried out in the southern tip of Arabia and brings new information about geology of the area with scarce geophysical data.

  14. Tossing on a Rotating Space Station

    NASA Astrophysics Data System (ADS)

    Paetkau, Mark

    2004-10-01

    The following analysis was inspired by a question posed by a listener of a radio science show. The listener asked the question: "If an astronaut in a space station that was rotating to simulate gravity threw a ball up, where would the ball go?" The physicist answered, "The ball would travel straight across the space station (assuming an open structure). "The main point is that to an outside observer the ball would not "fall" back down as on Earth. As I pondered this it occurred to me that while the answer is correct, it is a special case with a more general solution. Below is an analysis of the motions a thrown object can undergo on a rotating space station. The first part of the discussion is aimed at lower-level undergraduates who have a basic understanding of vectors and circular motion, and the motion is described from the point of view of an external reference frame. Further analysis of the motion by an observer on the space station is appropriate for upper-level students.

  15. Towing Asteroids with Gravity Tractors Enhanced by Tethers and Solar Sails

    NASA Technical Reports Server (NTRS)

    Shen, Haijun; Roithmayr, Carlos M.

    2015-01-01

    Material collected from an asteroid's surface can be used to increase gravitational attraction between the asteroid and a Gravity Tractor (GT); the spacecraft therefore operates more effectively and is referred to as an Enhanced Gravity Tractor (EGT). The use of tethers and solar sails to further improve effectiveness and simplify operations is investigated. By employing a tether, the asteroidal material can be placed close to the asteroid while the spacecraft is stationed farther away, resulting in a better safety margin and improved thruster efficiency. A solar sail on a spacecraft can naturally provide radial offset and inter-spacecraft separation required for multiple EGTs.

  16. Crustal Movements and Gravity Variations in the Southeastern Po Plain, Italy

    NASA Astrophysics Data System (ADS)

    Zerbini, S.; Bruni, S.; Errico, M.; Santi, E.; Wilmes, H.; Wziontek, H.

    2014-12-01

    At the Medicina observatory, in the southeastern Po Plain, in Italy, we have started a project of continuous GPS and gravity observations in mid 1996. The experiment, focused on a comparison between height and gravity variations, is still ongoing; these uninterrupted time series certainly constitute a most important data base to observe and estimate reliably long-period behaviors but also to derive deeper insights on the nature of the crustal deformation. Almost two decades of continuous GPS observations from two closely located receivers have shown that the coordinate time series are characterized by linear and non-linear variations as well as by sudden jumps. Both over long- and short-period time scales, the GPS height series show signals induced by different phenomena, for example, those related to mass transport in the Earth system. Seasonal effects are clearly recognizable and are mainly associated with the water table seasonal behavior. To understand and separate the contribution of different forcings is not an easy task; to this end, the information provided by the superconducting gravimeter observations and also by absolute gravity measurements offers a most important means to detect and understand mass contributions. In addition to GPS and gravity data, at Medicina, a number of environmental parameters time series are also regularly acquired, among them water table levels. We present the results of study investigating correlations between height, gravity and environmental parameters time series.

  17. Michigan Magnetic and Gravity Maps and Data: A Website for the Distribution of Data

    USGS Publications Warehouse

    Daniels, David L.; Kucks, Robert P.; Hill, Patricia L.; Snyder, Stephen L.

    2009-01-01

    This web site provides the best available, public-domain, aeromagnetic and gravity data in the State of Michigan and merges these data into composite grids that are available for downloading. The magnetic grid is compiled from 25 separate magnetic surveys that have been knit together to form a single composite digital grid and map. The magnetic survey grids have been continued to 305 meters (1,000 feet) above ground and merged together to form the State compilation. A separate map shows the location of the aeromagnetic surveys, color-coded to the survey flight-line spacing. In addition, a complete Bouguer gravity anomaly grid and map were generated from more than 20,000 gravity station measurements from 33 surveys. A table provides the facts about each gravity survey where known.

  18. Oregon Magnetic and Gravity Maps and Data: A Web Site for Distribution of Data

    USGS Publications Warehouse

    Roberts, Carter W.; Kucks, Robert P.; Hill, Patricia L.

    2008-01-01

    This web site gives the results of a USGS project to acquire the best available, public-domain, aeromagnetic and gravity data in the United States and merge these data into uniform, composite grids for each State. The results for the State of Oregon are presented here on this site. Files of aeromagnetic and gravity grids and images are available for these States for downloading. In Oregon, 49 magnetic surveys have been knit together to form a single digital grid and map. Also, a complete Bouguer gravity anomaly grid and map was generated from 40,665 gravity station measurements in and adjacent to Oregon. In addition, a map shows the location of the aeromagnetic surveys, color-coded to the survey flight-line spacing. This project was supported by the Mineral Resource Program of the USGS.

  19. Space Station tethered elevator system

    NASA Technical Reports Server (NTRS)

    Haddock, Michael H.; Anderson, Loren A.; Hosterman, K.; Decresie, E.; Miranda, P.; Hamilton, R.

    1989-01-01

    The optimized conceptual engineering design of a space station tethered elevator is presented. The tethered elevator is an unmanned, mobile structure which operates on a ten-kilometer tether spanning the distance between Space Station Freedom and a platform. Its capabilities include providing access to residual gravity levels, remote servicing, and transportation to any point along a tether. The report discusses the potential uses, parameters, and evolution of the spacecraft design. Emphasis is placed on the elevator's structural configuration and three major subsystem designs. First, the design of elevator robotics used to aid in elevator operations and tethered experimentation is presented. Second, the design of drive mechanisms used to propel the vehicle is discussed. Third, the design of an onboard self-sufficient power generation and transmission system is addressed.

  20. The study on the Layout of the Charging Station in Chengdu

    NASA Astrophysics Data System (ADS)

    Cai, yun; Zhang, wanquan; You, wei; Mao, pan

    2018-03-01

    In this paper, the comprehensive analysis of the factors affecting the layout of the electric car, considering the principle of layout of the charging station. Using queuing theory in operational research to establish mathematical model and basing on the principle of saving resource and convenient owner to optimize site number. Combining the theory of center to determine the service radius, Using the Gravity method to determine the initial location, Finally using the method of center of gravity to locate the charging station’s location.

  1. On the evaluation of the absolute photon energy of Cu Kα, β lines using 4-crystal X -ray spectrometer

    NASA Astrophysics Data System (ADS)

    Ito, Yoshiaki; Tochio, Tatsunori; Fukushima, Sei

    A 4-crystal X-ray spectrometer was designed based on a 2-crystal X-ray spectrometer to be able to perform the absolute measurement of Bragg angle. This basic thought based on 2 crystals dates back to the times to A.Compton etc.. Because a distortion to give the crystal by the adhesive when a crystal was glued, greatly affected the X-rays profile, we changed it to the channel cut crystal without a free distortion as for having made each crystal of 2-crystal a channel cut. The influence of the foot in the spectral profile is more suppressed because four times of reflections reflect it. It is a high resolution so as not to need to consider instrumental function by the reflection degree that a specific atomic analysis can be executed with the chemical state which it is possible for making the placement of the 4-crystal (+, +) setting. This type of spectrum device is first time in the world. Because the absolute measurement of 2 θ angles is enabled by (+,-) and (+, +) setting from the center of gravity position of the rocking curve and the center of gravity position of the X-rays spectrum, we may measure the absolute value of the X-ray photon energy. Because we evaluated the energy of the Cu Kα , β lines, we report it. We acknowledge financial support for the measurements of a part of the data by the REXDAB collaboration that was initiated within the International Fundamental Parameter Initiative.

  2. Indications of correlation between gravity measurements and isoseismal maps. A case study of Athens basin (Greece)

    NASA Astrophysics Data System (ADS)

    Dilalos, S.; Alexopoulos, J. D.

    2017-05-01

    In this paper, we discuss the correlation between isoseismal contour maps and gravity residual anomaly maps and how it might contribute to the characterization of vulnerable areas to earthquake damage, especially in urban areas, where the geophysical data collection is difficult. More specifically, we compare a couple of isoseismal maps that have been produced and published after the catastrophic earthquake of 7th September 1999 (5.9R) in Athens, the metropolis of Greece, with the residual map produced from the processing and data reduction of a gravity survey that has been carried out in the Athens basin recently. The geologic and tectonic regime of the Athens basin is quite complicated and it is still being updated with new elements. Basically it is comprised of four different geotectonic units, one of them considered as the autochthon. During the gravity investigation, 807 gravity stations were collected, based on a grid plan with spacing almost 1 km, covering the entire basin and supported by a newly established gravity base network comprised by thirteen bases. Differential DGPS technique was used for the accurate measurement of all the gravity stations and bases coordinates. After the appropriate data reduction and the construction of the Complete Bouguer Anomaly map, we applied FFT filtering in order to remove the regional component and produce the Residual Anomaly Map. The comparison of the Residual Anomaly Map with the isoseismal contours revealed that the areas with the most damage because of the earthquake were located in the areas with the minimum values of the Residual Anomaly Map.

  3. WILSON-BAPPU EFFECT: EXTENDED TO SURFACE GRAVITY

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Park, Sunkyung; Kang, Wonseok; Lee, Jeong-Eun

    2013-10-01

    In 1957, Wilson and Bappu found a tight correlation between the stellar absolute visual magnitude (M{sub V} ) and the width of the Ca II K emission line for late-type stars. Here, we revisit the Wilson-Bappu relationship (WBR) to claim that the WBR can be an excellent indicator of stellar surface gravity of late-type stars as well as a distance indicator. We have measured the width (W) of the Ca II K emission line in high-resolution spectra of 125 late-type stars obtained with the Bohyunsan Optical Echelle Spectrograph and adopted from the Ultraviolet and Visual Echelle Spectrograph archive. Based onmore » our measurement of the emission line width (W), we have obtained a WBR of M{sub V} = 33.76 - 18.08 log W. In order to extend the WBR to being a surface gravity indicator, stellar atmospheric parameters such as effective temperature (T{sub eff}), surface gravity (log g), metallicity ([Fe/H]), and micro-turbulence ({xi}{sub tur}) have been derived from self-consistent detailed analysis using the Kurucz stellar atmospheric model and the abundance analysis code, MOOG. Using these stellar parameters and log W, we found that log g = -5.85 log W+9.97 log T{sub eff} - 23.48 for late-type stars.« less

  4. Monitoring gravity and water storage changes in northern Benin

    NASA Astrophysics Data System (ADS)

    Hector, B.; Hinderer, J.; Boy, J.; Calvo, M.; Séguis, L.; Descloitres, M.; Cohard, J.; Rosat, S.; Riccardi, U.; Galle, S.

    2013-12-01

    The humid sudanian zone of West-Africa undergoes a monsoon climate, implying a strong seasonality in water storage changes (WSC). The GHYRAF (Gravity and Hydrology in Africa) project aims at monitoring both these local and non-local hydrological contributions with the main gravity sensors available today (FG5 absolute gravimeter, superconducting gravimeter -SG- and CG5 micro-gravimeter). The study area is located in hard-rock basement context in Djougou, northern Benin, and is also part of the long-term observing system AMMA-Catch, and thus under intense hydro-meteorological monitoring (rainfall, soil moisture, water table, evapotranspiration, ...). Gravity-derived WSC are compared to hydrological data and to physically-based or conceptual hydrological models calibrated on these data. This presentation shows the results and limitations of each gravimeter in the context of WSC retrieval. This site was first measured with a FG5 absolute gravimeter four times a year from 2008 to 2013. This can be considered as a high sampling rate, given the remote location and the complexity of FG5 carriage and installation. It allowed to derive an average specific yield for the local aquifer, and preliminary estimates of seasonal WSC (up to 120 nm/s2 - 270mm). Yet the lack of continuity in the data avoids further investigations. The SG-060 superconducting gravimeter has been installed in 2010 in order to monitor gravity response to WSC in a continuous way. A strong drift is present (230nm/s2/yr), and FG5 data together with a-priori information on WSC are needed for estimating its effect. Also, frequent power-failures lead to some significant gaps and offsets during which fast WSC may occur (e.g. rain), yielding to a challenging correction for these events. The retrieval of inter-annual WSC suffers from these strong and limiting instrumental effects. At higher frequencies, up to a few days, continuous gravity monitoring may help to quantify evapotranspiration (ET), a poorly

  5. Hopping locomotion at different gravity: metabolism and mechanics in humans.

    PubMed

    Pavei, Gaspare; Minetti, Alberto E

    2016-05-15

    Previous literature on the effects of low gravity on the mechanics and energetics of human locomotion already dealt with walking, running, and skipping. The aim of the present study is to obtain a comprehensive view on that subject by including measurements of human hopping in simulated low gravity, a gait often adopted in many Apollo Missions and documented in NASA footage. Six subjects hopped at different speeds at terrestrial, Martian, and Lunar gravity on a treadmill while oxygen consumption and 3D body kinematic were sampled. Results clearly indicate that hopping is too metabolically expensive to be a sustainable locomotion on Earth but, similarly to skipping (and running), its economy greatly (more than ×10) increases at lower gravity. On the Moon, the metabolic cost of hopping becomes even lower than that of walking, skipping, and running, but the general finding is that gaits with very different economy on Earth share almost the same economy on the Moon. The mechanical reasons for such a decrease in cost are discussed in the paper. The present data, together with previous findings, will allow also to predict the aerobic traverse range/duration of astronauts when getting far from their base station on low gravity planets. Copyright © 2016 the American Physiological Society.

  6. Interpretation of Local Gravity Anomalies in Northern New York

    NASA Astrophysics Data System (ADS)

    Revetta, F. A.

    2004-05-01

    About 10,000 new gravity measurements at a station spacing of 1 to 2 Km were made in the Adirondack Mountains, Lake Champlain Valley, St. Lawrence River Valley and Tug Hill Plateau. These closely spaced gravity measurements were compiled to construct computer contoured gravity maps of the survey areas. The gravity measurements reveal local anomalies related to seismicity, faults, mineral resources and gas fields that are not seen in the regional gravity mapping. In northern New York gravity and seismicity maps indicate epicenters are concentrated in areas of the most pronounced gravity anomalies along steep gravity gradients. Zones of weakness along the contacts of these lithologies of different density could possibly account for the earthquakes in this high stress area. Also, a computer contoured gravity map of the 5.3 magnitude Au Sable Forks earthquake of April 20, 2002 indicates the epicenter lies along a north-south trending gravity gradient produced by a high angle fault structure separating a gravity low in the west from high gravity in the east. In the St. Lawrence Valley, the Carthage-Colton Mylonite Zone, a major northeast trending structural boundary between the Adirondack Highlands and Northwest Lowlands, is represented as a steep gravity gradient extending into the eastern shore of Lake Ontario. At Russell, New York near the CCMZ, a small circular shaped gravity high coincides with a cluster of earthquakes. The coincidence of the epicenters over the high may indicate stress amplification at the boundary of a gabbro pluton. The Morristown fault located in the Morristown Quadrangle in St. Lawrence County produces both gravity and magnetic anomalies due to Precambrian Basement faulting. This faulting indicates control of the Morristown fault in the overlying Paleozoics by the Precambrian faults. Gravity and magnetic anomalies also occur over proposed extensions of the Gloucester and Winchester Springs faults into northern New York. Gravity and magnetic

  7. Temporal gravity variations associated with the November 1975 deflation of Kilauea Volcano

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jachens, R.; Eaton, G.; Lipman, P.

    1976-12-01

    Repeated high-precision gravity measurements made near the summit of Kilauea Volcano, Hawaii have revealed temporal variations in gravity associated with the deflation of the volcano that followed the earthquake and eruption of November 29, 1975. Gravity differences with respect to a base station located on the south flank of Mauna Loa were measured at 18 sites within 5 km of Kilauea Crater. The original survey, conducted between November 10 and November 23, 1975, was repeated during the two weeks following the earthquake. Standard errors of the gravity differences measured during both surveys average about 5 ..mu..gal. These two surveys indicatemore » that gravity at sites near the summit of Kilauea increased with respect to gravity at sites located away from the summit. The pattern of gravity increase is roughly radially symmetrical about the geodetically determined locus of this deflation event, located approximately 1 km southeast of Kilauea Crater, and has a half-width of 2.2 km. The gravity changes correlate closely with elevation changes that occurred between level surveys conducted on September 22, 1975 and January 8, 1976. The relation between gravity change and elevation change (-1.70 +- 0.07 (s.e.) ..mu..gal/cm)) determined from these data shows that the local mass distribution beneath the summit of Kilauea changed during the time between the surveys. Mass balance calculations indicate that the volume of subsidence is too small to account for the gravity changes, presumably because some magma moved away from the summit area without complete collapse of the resulting voids.« less

  8. Building complex simulations rapidly using MATRIX(x): The Space Station redesign

    NASA Technical Reports Server (NTRS)

    Carrington, C. K.

    1994-01-01

    MSFC's quick response to the Space Station redesign effort last year required the development of a computer simulation to model the attitude and station-keeping dynamics of a complex body with rotating solar arrays in orbit around the Earth. The simulation was written using a rapid-prototyping graphical simulation and design tool called MATRIX(x) and provided the capability to quickly remodel complex configuration changes by icon manipulation using a mouse. The simulation determines time-dependent inertia properties, and models forces and torques from gravity-gradient, solar radiation, and aerodynamic disturbances. Surface models are easily built from a selection of beams, plates, tetrahedrons, and cylinders. An optimization scheme was written to determine the torque equilibrium attitudes that balance gravity-gradient and aerodynamic torques over an orbit, and propellant-usage estimates were determined. The simulation has been adapted to model the attitude dynamics for small spacecraft.

  9. Gravity and Magnetic Surveys Over the Santa Rita Fault System, Southeastern Arizona

    USGS Publications Warehouse

    Hegmann, Mary

    2001-01-01

    Gravity and magnetic surveys were performed in the northeast portion of the Santa Rita Experimental Range, in southeastern Arizona, to identify faults and gain a better understanding of the subsurface geology. A total of 234 gravity stations were established, and numerous magnetic data were collected with portable and truck-mounted proton precession magnetometers. In addition, one line of very low frequency electromagnetic data was collected together with magnetic data. Gravity anomalies are used to identify two normal faults that project northward toward a previously identified fault. The gravity data also confirm the location of a second previously interpreted normal fault. Interpretation of magnetic anomaly data indicates the presence of a higher-susceptibility sedimentary unit located beneath lowersusceptibility surficial sediments. Magnetic anomaly data identify a 1-km-wide negative anomaly east of these faults caused by an unknown source and reveal the high variability of susceptibility in the Tertiary intrusive rocks in the area.

  10. A Combined Gravity Compensation Method for INS Using the Simplified Gravity Model and Gravity Database.

    PubMed

    Zhou, Xiao; Yang, Gongliu; Wang, Jing; Wen, Zeyang

    2018-05-14

    In recent decades, gravity compensation has become an important way to reduce the position error of an inertial navigation system (INS), especially for a high-precision INS, because of the extensive application of high precision inertial sensors (accelerometers and gyros). This paper first deducts the INS's solution error considering gravity disturbance and simulates the results. Meanwhile, this paper proposes a combined gravity compensation method using a simplified gravity model and gravity database. This new combined method consists of two steps all together. Step 1 subtracts the normal gravity using a simplified gravity model. Step 2 first obtains the gravity disturbance on the trajectory of the carrier with the help of ELM training based on the measured gravity data (provided by Institute of Geodesy and Geophysics; Chinese Academy of sciences), and then compensates it into the error equations of the INS, considering the gravity disturbance, to further improve the navigation accuracy. The effectiveness and feasibility of this new gravity compensation method for the INS are verified through vehicle tests in two different regions; one is in flat terrain with mild gravity variation and the other is in complex terrain with fierce gravity variation. During 2 h vehicle tests, the positioning accuracy of two tests can improve by 20% and 38% respectively, after the gravity is compensated by the proposed method.

  11. A Combined Gravity Compensation Method for INS Using the Simplified Gravity Model and Gravity Database

    PubMed Central

    Zhou, Xiao; Yang, Gongliu; Wang, Jing; Wen, Zeyang

    2018-01-01

    In recent decades, gravity compensation has become an important way to reduce the position error of an inertial navigation system (INS), especially for a high-precision INS, because of the extensive application of high precision inertial sensors (accelerometers and gyros). This paper first deducts the INS’s solution error considering gravity disturbance and simulates the results. Meanwhile, this paper proposes a combined gravity compensation method using a simplified gravity model and gravity database. This new combined method consists of two steps all together. Step 1 subtracts the normal gravity using a simplified gravity model. Step 2 first obtains the gravity disturbance on the trajectory of the carrier with the help of ELM training based on the measured gravity data (provided by Institute of Geodesy and Geophysics; Chinese Academy of sciences), and then compensates it into the error equations of the INS, considering the gravity disturbance, to further improve the navigation accuracy. The effectiveness and feasibility of this new gravity compensation method for the INS are verified through vehicle tests in two different regions; one is in flat terrain with mild gravity variation and the other is in complex terrain with fierce gravity variation. During 2 h vehicle tests, the positioning accuracy of two tests can improve by 20% and 38% respectively, after the gravity is compensated by the proposed method. PMID:29757983

  12. Binary Colloidal Alloy Test-3 (BCAT-3) Tabletop Space Station Experiment Continues

    NASA Technical Reports Server (NTRS)

    Meyer, William V.

    2005-01-01

    "As above, so below," thus begins the Emerald Tablet that was inscribed in 300 B.C., long before we could look into the heavens and see a space station that might serve as a platform for exploring other worlds and for exploring the natural ways that order arises out of chaos. To raze the ancient intent of this quote (and lift it out of context), we note that the effects of gravity would be balanced (removed) at the center of the Earth (below) and that this is also the case aboard the International Space Station (above). Yet, those of us on Earth are caught in the middle, where the effects of gravity are profound and disturbing for observers wanting to study nature s self-organizing tendencies, tendencies that are masked by sedimentation and convection on Earth.

  13. International Space Station (ISS)

    NASA Image and Video Library

    1998-11-01

    This photograph shows the U.S. Laboratory Module (also called Destiny) for the International Space Station (ISS), in the Space Station manufacturing facility at the Marshall Space Flight Center, being readied for shipment to the Kennedy Space Center. The U.S. Laboratory module is the centerpiece of the ISS, where science experiments will be performed in the near-zero gravity of space. The Destiny Module was launched aboard the Space Shuttle orbiter Atlantis (STS-67 mission) on February 7, 2001. The aluminum module is 8.5 meters (28 feet) long and 4.3 meters (14 feet) in diameter. The laboratory consists of three cylindrical sections and two endcones with hatches that will be mated to other station components. A 50.9-centimeter- (20-inch-) diameter window is located on one side of the center module segment. This pressurized module is designed to accommodate pressurized payloads. It has a capacity of 24 rack locations, and payload racks will occupy 13 locations especially designed to support experiments. The ISS is a multidisciplinary laboratory, technology test bed, and observatory that will provide unprecedented undertakings in scientific, technological, and international experimentation.

  14. International Space Station (ISS)

    NASA Image and Video Library

    1997-01-01

    In this photograph, the U.S. Laboratory Module (also called Destiny) for the International Space Station (ISS) is shown under construction in the West High Bay of the Space Station manufacturing facility (building 4708) at the Marshall Space Flight Center. The U.S. Laboratory module is the centerpiece of the ISS, where science experiments will be performed in the near-zero gravity of space. The Destiny Module was launched aboard the Space Shuttle orbiter Atlantis (STS-98 mission) on February 7, 2001. The aluminum module is 8.5 meters (28 feet) long and 4.3 meters (14 feet) in diameter. The laboratory consists of three cylindrical sections and two endcones with hatches that will be mated to other station components. A 50.9-centimeter- (20-inch-) diameter window is located on one side of the center module segment. This pressurized module is designed to accommodate pressurized payloads. It has a capacity of 24 rack locations, and payload racks will occupy 13 locations especially designed to support experiments. The ISS is a multidisciplinary laboratory, technology test bed, and observatory that will provide unprecedented undertakings in scientific, technological, and international experimentation.

  15. International Space Station (ISS)

    NASA Image and Video Library

    1997-11-01

    In this photograph, the U.S. Laboratory Module (also called Destiny) for the International Space Station (ISS) is shown under construction in the West High Bay of the Space Station manufacturing facility (building 4708) at the Marshall Space Flight Center. The U.S. Laboratory module is the centerpiece of the ISS, where science experiments will be performed in the near-zero gravity of space. The Destiny Module was launched aboard the Space Shuttle orbiter Atlantis (STS-98 mission) on February 7, 2001. The aluminum module is 8.5 meters (28 feet) long and 4.3 meters (14 feet) in diameter. The laboratory consists of three cylindrical sections and two endcones with hatches that will be mated to other station components. A 50.9-centimeter- (20-inch-) diameter window is located on one side of the center module segment. This pressurized module is designed to accommodate pressurized payloads. It has a capacity of 24 rack locations, and payload racks will occupy 13 locations especially designed to support experiments. The ISS is a multidisciplinary laboratory, technology test bed, and observatory that will provide unprecedented undertakings in scientific, technological, and international experimentation.

  16. Integrating a Gravity Simulation and Groundwater Modeling on the Calibration of Specific Yield for Choshui Alluvial Fan

    NASA Astrophysics Data System (ADS)

    Chang, Liang Cheng; Tsai, Jui pin; Chen, Yu Wen; Way Hwang, Chein; Chung Cheng, Ching; Chiang, Chung Jung

    2014-05-01

    that the proposed approach is correct and reasonable. In Tu-ku and Ke-cuo, the ratios of the gravity variation between observed gravity residuals and simulated gravities are approximate 1.8 and 50, respectively. The Sy values of these two stations are modified 1.8 and 50 times the original values. These modified Sy values are assigned to the groundwater morel. After the parameter re-assignment, the simulated gravities meet the gravity residuals in these two stations. In conclusion, the study results show that the proposed approach has the potential to identify Sy without installing wells. Therefore, the proposed approach can be used to increase the spatial density of Sy and can conduct the recharge estimation with low uncertainty.

  17. Estimating the Earth's geometry, rotation and gravity field using a multi-satellite SLR solution

    NASA Astrophysics Data System (ADS)

    Stefka, V.; Blossfeld, M.; Mueller, H.; Gerstl, M.; Panafidina, N.

    2012-12-01

    Satellite Laser Ranging (SLR) is the unique technique to determine station coordinates, Earth Orientation Parameter (EOP) and Stokes coefficients of the Earth's gravity field in one common adjustment. These parameters form the so called "three pillars" (Plag & Pearlman, 2009) of the Global Geodetic Observing System (GGOS). In its function as official analysis center of the International Laser Ranging Service (ILRS), DGFI is developing and maintaining software to process SLR observations called "DGFI Orbit and Geodetic parameter estimation Software" (DOGS). The software is used to analyze SLR observations and to compute multi-satellite solutions. To take benefit of different orbit performances (e.g. inclination and altitude), a solution using ten different spherical satellites (ETALON1/2, LAGEOS1/2, STELLA, STARLETTE, AJISAI, LARETS, LARES, BLITS) covering the period of 12 years of observations is computed. The satellites are relatively weighted using a variance component estimation (VCE). The obtained weights are analyzed w.r.t. the potential of the satellite to monitor changes in the Earths geometry, rotation and gravity field. The estimated parameters (station coordinates and EOP) are validated w.r.t. official time series of the IERS. The Stokes coefficients are compared to recent gravity field solutions.

  18. Current Space Station Experiments Investigating Component Level Electronics Repair

    NASA Technical Reports Server (NTRS)

    Easton, John W.; Struk, Peter M.

    2010-01-01

    The Soldering in a Reduced Gravity Experiment (SoRGE) and Component Repair Experiment (CRE)-1 are tests performed on the International Space Station to determine the techniques, tools, and training necessary to allow future crews to perform manual electronics repairs at the component level. SoRGE provides information on the formation and internal structure of through-hole solder joints, illustrating the challenges and implications of soldering in reduced gravity. SoRGE showed a significant increase in internal void defects for joints formed in low gravity compared to normal gravity. Methods for mitigating these void defects were evaluated using a modified soldering process. CRE-1 demonstrated the removal, cleaning, and replacement of electronics components by manual means on functional circuit boards. The majority of components successful passed a post-repair functional test demonstrating the feasibility of component-level repair within the confines of a spacecraft. Together, these tasks provide information to recommend material and tool improvements, training improvements, and future work to help enable electronics repairs in future space missions.

  19. Plant biology in reduced gravity on the Moon and Mars.

    PubMed

    Kiss, J Z

    2014-01-01

    While there have been numerous studies on the effects of microgravity on plant biology since the beginning of the Space Age, our knowledge of the effects of reduced gravity (less than the Earth nominal 1 g) on plant physiology and development is very limited. Since international space agencies have cited manned exploration of Moon/Mars as long-term goals, it is important to understand plant biology at the lunar (0.17 g) and Martian levels of gravity (0.38 g), as plants are likely to be part of bioregenerative life-support systems on these missions. First, the methods to obtain microgravity and reduced gravity such as drop towers, parabolic flights, sounding rockets and orbiting spacecraft are reviewed. Studies on gravitaxis and gravitropism in algae have suggested that the threshold level of gravity sensing is around 0.3 g or less. Recent experiments on the International Space Station (ISS) showed attenuation of phototropism in higher plants occurs at levels ranging from 0.l g to 0.3 g. Taken together, these studies suggest that the reduced gravity level on Mars of 0.38 g may be enough so that the gravity level per se would not be a major problem for plant development. Studies that have directly considered the impact of reduced gravity and microgravity on bioregenerative life-support systems have identified important biophysical changes in the reduced gravity environments that impact the design of these systems. The author suggests that the current ISS laboratory facilities with on-board centrifuges should be used as a test bed in which to explore the effects of reduced gravity on plant biology, including those factors that are directly related to developing life-support systems necessary for Moon and Mars exploration. © 2013 German Botanical Society and The Royal Botanical Society of the Netherlands.

  20. The opportunities for space biology research on the Space Station

    NASA Technical Reports Server (NTRS)

    Ballard, Rodney W.; Souza, Kenneth A.

    1987-01-01

    The life sciences research facilities for the Space Station are being designed to accommodate both animal and plant specimens for long durations studies. This will enable research on how living systems adapt to microgravity, how gravity has shaped and affected life on earth, and further the understanding of basic biological phenomena. This would include multigeneration experiments on the effects of microgravity on the reproduction, development, growth, physiology, behavior, and aging of organisms. To achieve these research goals, a modular habitat system and on-board variable gravity centrifuges, capable of holding various animal, plant, cells and tissues, is proposed for the science laboratory.

  1. Gravity Field Solution Derived from Recent Releases of GOCE-Based Geopotential Models and Terrestrial Gravity Observations over The Kingdom of Saudi Arabia

    NASA Astrophysics Data System (ADS)

    Alothman, Abdulaziz; Elsaka, Basem

    2015-03-01

    The free air gravity anomalies over Saudi Arabia (KSA) has been estimated from the final releases of GOCE-based global geopotential models (GGMs) compared with the terrestrial gravity anomalies of 3554 sites. Two GGMs; EGM08 and Eigen-6C3 have been applied. The free-air anomalies from GOCE-based, ΔgGGM, have been calculated over the 3554 stations in the medium and short spectrum of gravity wavelength of d/o 100, …, 250 (with 10 step). The short spectrum has been compensated once from d/o 101, …, 251 to 2190 and 1949 using EGM08 and Eigen-6C3 (i.e. ΔgGGM), respectively. The very short component was determined using residual terrain modelling approach. Our findings show firstly that the EGM08 is more reliable than Eigen-6C3. Second, the GOCE-based GGMs provide similar results within the spectral wavelength band from d/o 100 to d/o 180. Beyond d/o 180 till d/o 250, we found that GOCE-based TIM model releases provide substantial improvements within the spectral band from d/o 220 to d/o 250 with respect to the DIR releases. Third, the TIM_r5 model provides the least standard deviations (st. dev.) in terms of gravity anomalies.

  2. A simple 5-DOF walking robot for space station application

    NASA Technical Reports Server (NTRS)

    Brown, H. Benjamin, Jr.; Friedman, Mark B.; Kanade, Takeo

    1991-01-01

    Robots on the NASA space station have a potential range of applications from assisting astronauts during EVA (extravehicular activity), to replacing astronauts in the performance of simple, dangerous, and tedious tasks; and to performing routine tasks such as inspections of structures and utilities. To provide a vehicle for demonstrating the pertinent technologies, a simple robot is being developed for locomotion and basic manipulation on the proposed space station. In addition to the robot, an experimental testbed was developed, including a 1/3 scale (1.67 meter modules) truss and a gravity compensation system to simulate a zero-gravity environment. The robot comprises two flexible links connected by a rotary joint, with a 2 degree of freedom wrist joints and grippers at each end. The grippers screw into threaded holes in the nodes of the space station truss, and enable it to walk by alternately shifting the base of support from one foot (gripper) to the other. Present efforts are focused on mechanical design, application of sensors, and development of control algorithms for lightweight, flexible structures. Long-range research will emphasize development of human interfaces to permit a range of control modes from teleoperated to semiautonomous, and coordination of robot/astronaut and multiple-robot teams.

  3. Application of a space station to communications satellites

    NASA Technical Reports Server (NTRS)

    Ramler, J. R.

    1983-01-01

    The economic benefits of a space station relative to communications satellites are discussed in terms of technology experiments, spacecraft checkout, repair, servicing, and refurbishment (RSR), and mating an OTV with satellites for boost to GEO. The zero gravity, vacuum conditions, and atmosphere free long ranges are environmental features that can be used for testing large, flexible antennas and laser communications devices. Some resistance might be encountered to checkout in LEO due to the substantial success of launches to GEO without LEO checkout. However, new generations of larger, more complex satellites may warrant the presence of a space station to verify performance of new spacecraft. One RSR positive aspect for a space station is as a storage site for propellant, as well as for reusable OTV booster engines. Also, the space station can serve as a base for manned or unmanned repair spacecraft which will travel to GEO to fix malfunctions in geostationary satellites.

  4. Space Station Environmental Health System water quality monitoring

    NASA Technical Reports Server (NTRS)

    Vincze, Johanna E.; Sauer, Richard L.

    1990-01-01

    One of the unique aspects of the Space Station is that it will be a totally encapsulated environment and the air and water supplies will be reclaimed for reuse. The Environmental Health System, a subsystem of CHeCS (Crew Health Care System), must monitor the air and water on board the Space Station Freedom to verify that the quality is adequate for crew safety. Specifically, the Water Quality Subsystem will analyze the potable and hygiene water supplies regularly for organic, inorganic, particulate, and microbial contamination. The equipment selected to perform these analyses will be commercially available instruments which will be converted for use on board the Space Station Freedom. Therefore, the commercial hardware will be analyzed to identify the gravity dependent functions and modified to eliminate them. The selection, analysis, and conversion of the off-the-shelf equipment for monitoring the Space Station reclaimed water creates a challenging project for the Water Quality engineers and scientists.

  5. Vacuum/Zero Net-Gravity Application for On-Orbit TPS Tile Repair

    NASA Technical Reports Server (NTRS)

    Harvey, Gale A.; Humes, Donald H.; Siochi, Emilie J.

    2004-01-01

    The Orbiter Columbia catastrophically failed during reentry February 1, 2003. All Space Shuttle flights were suspended, including logistics support for the International Space Station. NASA Langley Research Center s (LaRC) Structures and Materials Competency is performing characterizations of candidate materials for on-orbit repair of orbiter Thermal Protection System (TPS) tiles to support Return-to-Flight activities led by Johnson Space Center (JSC). At least ten materials properties or attributes (adhesion to damage site, thermal protection, char/ash strength, thermal expansion, blistering, flaming, mixing ease, application in vacuum and zero gravity, cure time, shelf or storage life, and short-term outgassing and foaming) of candidate materials are of interest for on-orbit repair. This paper reports application in vacuum and zero net-gravity (for viscous flow repair materials). A description of the test apparatus and preliminary results of several candidate materials are presented. The filling of damage cavities is different for some candidate repair materials in combined vacuum and zero net-gravity than in either vacuum or zero net-gravity alone.

  6. Global height datum unification: a new approach in gravity potential space

    NASA Astrophysics Data System (ADS)

    Ardalan, A. A.; Safari, A.

    2005-12-01

    The problem of “global height datum unification” is solved in the gravity potential space based on: (1) high-resolution local gravity field modeling, (2) geocentric coordinates of the reference benchmark, and (3) a known value of the geoid’s potential. The high-resolution local gravity field model is derived based on a solution of the fixed-free two-boundary-value problem of the Earth’s gravity field using (a) potential difference values (from precise leveling), (b) modulus of the gravity vector (from gravimetry), (c) astronomical longitude and latitude (from geodetic astronomy and/or combination of (GNSS) Global Navigation Satellite System observations with total station measurements), (d) and satellite altimetry. Knowing the height of the reference benchmark in the national height system and its geocentric GNSS coordinates, and using the derived high-resolution local gravity field model, the gravity potential value of the zero point of the height system is computed. The difference between the derived gravity potential value of the zero point of the height system and the geoid’s potential value is computed. This potential difference gives the offset of the zero point of the height system from geoid in the “potential space”, which is transferred into “geometry space” using the transformation formula derived in this paper. The method was applied to the computation of the offset of the zero point of the Iranian height datum from the geoid’s potential value W 0=62636855.8 m2/s2. According to the geometry space computations, the height datum of Iran is 0.09 m below the geoid.

  7. Astrobee: Space Station Robotic Free Flyer

    NASA Technical Reports Server (NTRS)

    Provencher, Chris; Bualat, Maria G.; Barlow, Jonathan; Fong, Terrence W.; Smith, Marion F.; Smith, Ernest E.; Sanchez, Hugo S.

    2016-01-01

    Astrobee is a free flying robot that will fly inside the International Space Station and primarily serve as a research platform for robotics in zero gravity. Astrobee will also provide mobile camera views to ISS flight and payload controllers, and collect various sensor data within the ISS environment for the ISS Program. Astrobee consists of two free flying robots, a dock, and ground data system. This presentation provides an overview, high level design description, and project status.

  8. International Space Station Node 1 is moved for leak test

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Node 1, the first element for the International Space Station, and attached Pressurized Mating Adapter-1 continue with prelaunch preparation activities at KSC's Space Station Processing Facility. Node 1 is a connecting passageway to the living and working areas of the space station. The node is being removed from the element rotation stand, or test stand, where it underwent an interim weight and center of gravity determination. (The final determination is planned to be performed prior to transporting Node 1 to the launch pad.) Now the node is being moved to the Shuttle payload transportation canister, where the doors will be closed for a two-week leak check. Node 1 is scheduled to fly on STS-88.

  9. Node 1 and PMA-1 are moved for weight and center of gravity determination

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Node 1, the first U.S. element for the International Space Station, and Pressurized Mating Adapter-1 (PMA-1) continue with prelaunch preparation activities at KSC's Space Station Processing Facility. Node 1 is a connecting passageway to the living and working areas of the space station. The node and PMA-1 are being moved to an element rotation stand, or test stand, where they will undergo an interim weight and center of gravity determination. The final determination is planned to be performed prior to transporting Node 1 to the launch pad. Node 1 is scheduled to fly on STS-88.

  10. Teaching Absolute Value Meaningfully

    ERIC Educational Resources Information Center

    Wade, Angela

    2012-01-01

    What is the meaning of absolute value? And why do teachers teach students how to solve absolute value equations? Absolute value is a concept introduced in first-year algebra and then reinforced in later courses. Various authors have suggested instructional methods for teaching absolute value to high school students (Wei 2005; Stallings-Roberts…

  11. Local and Catchment-Scale Water Storage Changes in Northern Benin Deduced from Gravity Monitoring at Various Time-Scales

    NASA Astrophysics Data System (ADS)

    Hinderer, J.; Hector, B.; Séguis, L.; Descloitres, M.; Cohard, J.; Boy, J.; Calvo, M.; Rosat, S.; Riccardi, U.; Galle, S.

    2013-12-01

    Water storage changes (WSC) are investigated by the mean of gravity monitoring in Djougou, northern Benin, in the frame of the GHYRAF (Gravity and Hydrology in Africa) project. In this area, WSC are 1) part of the control system for evapotranspiration (ET) processes, a key variable of the West-African monsoon cycle and 2) the state variable for resource management, a critical issue in storage-poor hard rock basement contexts such as in northern Benin. We show the advantages of gravity monitoring for analyzing different processes in the water cycle involved at various time and space scales, using the main gravity sensors available today (FG5 absolute gravimeter, superconducting gravimeter -SG- and CG5 micro-gravimeter). The study area is also part of the long-term observing system AMMA-Catch, and thus under intense hydro-meteorological monitoring (rain, soil moisture, water table level, ET ...). Gravity-derived WSC are compared at all frequencies to hydrological data and to hydrological models calibrated on these data. Discrepancies are analyzed to discuss the pros and cons of each approach. Fast gravity changes (a few hours) are significant when rain events occur, and involve different contributions: rainfall itself, runoff, fast subsurface water redistribution, screening effect of the gravimeter building and local topography. We investigate these effects and present the statistical results of a set of rain events recorded with the SG installed in Djougou since July 2010. The intermediate time scale of gravity changes (a few days) is caused by ET and both vertical and horizontal water redistribution. The integrative nature of gravity measurements does not allow to separate these different contributions, and the screening from the shelter reduces our ability to retrieve ET values. Also, atmospheric corrections are critical at such frequencies, and deserve some specific attention. However, a quick analysis of gravity changes following rain events shows that the

  12. The interaction between the tropopause inversion layer and the inertial gravity wave activities revealed by radiosonde observations at a midlatitude station

    NASA Astrophysics Data System (ADS)

    Zhang, Yehui; Zhang, Shaodong; Huang, Chunming; Huang, Kaiming; Gong, Yun; Gan, Quan

    2015-08-01

    The interaction between the tropopause inversion layer (TIL) and the inertial gravity wave (IGW) activities is first presented by using a high vertical resolution radiosonde data set at a midlatitude station, Boise, Idaho (43.57°N, 116.22°W), for the period 1998-2008. The tropopause-based vertical coordinate is used for the TIL detection, and for meticulously studying the IGW variation around the TIL, the broad spectral method is used for the IGW extraction. Generally, the TIL at the midlatitude station is stronger and thicker in winter and spring, which is consistent with previous studies. Our study confirmed the intense interaction between the TIL and IGW. It is found that the TIL not only could inhibit the upward propagation of IGWs from below but also imply the possible excitation links between the TIL and IGW. The results also indicate that the enhanced wind shear layer just 1 km above the tropopause may result in instability and finally leads to the IGW breaking and intensive turbulence. Subsequently, the IGW-induced intensive turbulence leads to strong wave energy dissipation and a downward heat flux. This downward heat transportation could significantly cool the tropopause, while it has only negligible thermal effect on the atmosphere above the tropopause. Then, the IGW-induced cooling at the tropopause makes the tropopause colder and sharper and finally forms the TIL. These suggest besides previously proposed mechanisms that IGWs also contribute greatly to the formation of TIL, which is consistent with a recent related simulation study.

  13. Absolute and convective instabilities of a film flow down a vertical fiber subjected to a radial electric field

    NASA Astrophysics Data System (ADS)

    Liu, Rong; Chen, Xue; Ding, Zijing

    2018-01-01

    We consider the motion of a gravity-driven flow down a vertical fiber subjected to a radial electric field. This flow exhibits rich dynamics including the formation of droplets, or beads, driven by a Rayleigh-Plateau mechanism modified by the presence of gravity as well as the Maxwell stress at the interface. A spatiotemporal stability analysis is performed to investigate the effect of electric field on the absolute-convective instability (AI-CI) characteristics. We performed a numerical simulation on the nonlinear evolution of the film to examine the transition from CI to AI regime. The numerical results are in excellent agreement with the spatiotemporal stability analysis. The blowup behavior of nonlinear simulation predicts the formation of touchdown singularity of the interface due to the effect of electric field. We try to connect the blowup behavior with the AI-CI characteristics. It is found that the singularities mainly occur in the AI regime. The results indicate that the film may have a tendency to form very sharp tips due to the enhancement of the absolute instability induced by the electric field. We perform a theoretical analysis to study the behaviors of the singularities. The results show that there exists a self-similarity between the temporal and spatial distances from the singularities.

  14. Space Station Biological Research Project.

    PubMed

    Johnson, C C; Wade, C E; Givens, J J

    1997-06-01

    To meet NASA's objective of using the unique aspects of the space environment to expand fundamental knowledge in the biological sciences, the Space Station Biological Research Project at Ames Research Center is developing, or providing oversight, for two major suites of hardware which will be installed on the International Space Station (ISS). The first, the Gravitational Biology Facility, consists of Habitats to support plants, rodents, cells, aquatic specimens, avian and reptilian eggs, and insects and the Habitat Holding Rack in which to house them at microgravity; the second, the Centrifuge Facility, consists of a 2.5 m diameter centrifuge that will provide acceleration levels between 0.01 g and 2.0 g and a Life Sciences Glovebox. These two facilities will support the conduct of experiments to: 1) investigate the effect of microgravity on living systems; 2) what level of gravity is required to maintain normal form and function, and 3) study the use of artificial gravity as a countermeasure to the deleterious effects of microgravity observed in the crew. Upon completion, the ISS will have three complementary laboratory modules provided by NASA, the European Space Agency and the Japanese space agency, NASDA. Use of all facilities in each of the modules will be available to investigators from participating space agencies. With the advent of the ISS, space-based gravitational biology research will transition from 10-16 day short-duration Space Shuttle flights to 90-day-or-longer ISS increments.

  15. Space Station Biological Research Project

    NASA Technical Reports Server (NTRS)

    Johnson, C. C.; Wade, C. E.; Givens, J. J.

    1997-01-01

    To meet NASA's objective of using the unique aspects of the space environment to expand fundamental knowledge in the biological sciences, the Space Station Biological Research Project at Ames Research Center is developing, or providing oversight, for two major suites of hardware which will be installed on the International Space Station (ISS). The first, the Gravitational Biology Facility, consists of Habitats to support plants, rodents, cells, aquatic specimens, avian and reptilian eggs, and insects and the Habitat Holding Rack in which to house them at microgravity; the second, the Centrifuge Facility, consists of a 2.5 m diameter centrifuge that will provide acceleration levels between 0.01 g and 2.0 g and a Life Sciences Glovebox. These two facilities will support the conduct of experiments to: 1) investigate the effect of microgravity on living systems; 2) what level of gravity is required to maintain normal form and function, and 3) study the use of artificial gravity as a countermeasure to the deleterious effects of microgravity observed in the crew. Upon completion, the ISS will have three complementary laboratory modules provided by NASA, the European Space Agency and the Japanese space agency, NASDA. Use of all facilities in each of the modules will be available to investigators from participating space agencies. With the advent of the ISS, space-based gravitational biology research will transition from 10-16 day short-duration Space Shuttle flights to 90-day-or-longer ISS increments.

  16. MX Siting Investigation. Gravity Survey - Sevier Desert Valley, Utah.

    DTIC Science & Technology

    1981-01-24

    Cheyenne, Wyoming. DMAHTC reduces the data to Simple Bouguer Anomaly (see Section A1.4, Appendix Al.0). The Defense Mapping Agency Aerospace Center...Desert Valley, Utah ......... 2 2 Topographic Setting - Sevier Desert Valley, Utah . 3 LIST OF DRAWINGS Drawing Number 1 Complete Bouguer Anomaly...gravity stations were distributed throughout the valley at an approxi- mate interval of 1.4 miles (2.3 km). Drawing 1 is a Complete Bouguer Anomaly

  17. Gravity and gravity gradient changes caused by a point dislocation

    NASA Astrophysics Data System (ADS)

    Huang, Jian-Liang; Li, Hui; Li, Rui-Hao

    1995-02-01

    In this paper we studied gravitational potential, gravity and its gradient changes, which are caused by a point dislocation, and gave the concise mathematical deduction with definite physical implication in dealing with the singular integral at a seismic source. We also analysed the features of the fields of gravity and gravity gradient, gravity-vertical-displacement gradient. The conclusions are: (1) Gravity and gravity gradient changes are very small with the change of vertical position; (2) Gravity change is much greater than the gravity gradient change which is not so distinct; (3) The gravity change due to redistribution of mass accounts for 10 50 percent of the total gravity change caused by dislocation. The signs (positive or negative) of total gravity change and vertical displacement are opposite each other at the same point for strike slip and dip slip; (4) Gravity-vertical-displacement-gradient is not constant; it manifests a variety of patterns for different dislocation models; (5) Gravity-vertical-displacement-gradient is approximately equal to apparent gravity-vertical-displacement-gradient.

  18. The small but clear gravity signal above the natural cave 'Grotta Gigante' (Trieste, Italy)

    NASA Astrophysics Data System (ADS)

    Braitenberg, Carla; Sampietro, Daniele; Zuliani, David; Barbagallo, Alfio; Fabris, Paolo; Fabbri, Julius; Rossi, Lorenzo; Handi Mansi, Ahmed

    2014-05-01

    Gravity observations are a powerful means for detecting underground mass changes. The Italian and Slovenian Karst has a number of explored caves, several are also touristic due to their size (e.g. Grotta Gigante in Italy; Skocjianske Jame and Postojnska Jama in Slovenia). Just a few years ago another big cave was discovered by chance close to Trieste when drilling a tunnel for a motor-highway, which shows that more caves are expected to be discovered in coming years. We have acquired the gravity field above the Grotta Gigante cave, a cave roughly 100 m high and 200 m long with a traditional spring-gravity meter (Lacoste&Romberg) and height measurements made with GPS and total station. The GPS was made with two different teams and processing algorithms, to cross-check accuracy and error estimate. Some stations had to be surveyed with a classical instrument due to the vegetation which concealed the satellite positioning signal. Here we present the results of the positioning acquisitions and the gravity field. The cave produces a signal of 1.5 mGal, with a clear elongated concentric symmetry. The survey shows that a systematic coverage of the Karst would have the benefit to recover the position of all of the greater existing caves. This will have a large impact on civil and environmental purposes, since it will for example allow to plan the urban development at a safety distance from subsurface caves.

  19. Modelling and simulation of Space Station Freedom berthing dynamics and control

    NASA Technical Reports Server (NTRS)

    Cooper, Paul A.; Garrison, James L., Jr.; Montgomery, Raymond C.; Wu, Shih-Chin; Stockwell, Alan E.; Demeo, Martha E.

    1994-01-01

    A large-angle, flexible, multibody, dynamic modeling capability has been developed to help validate numerical simulations of the dynamic motion and control forces which occur during berthing of Space Station Freedom to the Shuttle Orbiter in the early assembly flights. This paper outlines the dynamics and control of the station, the attached Shuttle Remote Manipulator System, and the orbiter. The simulation tool developed for the analysis is described and the results of two simulations are presented. The first is a simulated maneuver from a gravity-gradient attitude to a torque equilibrium attitude using the station reaction control jets. The second simulation is the berthing of the station to the orbiter with the station control moment gyros actively maintaining an estimated torque equilibrium attitude. The influence of the elastic dynamic behavior of the station and of the Remote Manipulator System on the attitude control of the station/orbiter system during each maneuver was investigated. The flexibility of the station and the arm were found to have only a minor influence on the attitude control of the system during the maneuvers.

  20. MX Siting Investigation Gravity Survey - Ralston Valley, Nevada.

    DTIC Science & Technology

    1981-08-20

    Center (DMAHTC), headquartered in Cheyenne. Wyoming. DMAHTC reduces the data to Simple Bouguer Anomaly (see Section A1.4, Appendix Al.0). The Defense...LIST OF DRAWINGS Drawing Number 1 Complete Bouguer Anomaly Contours In Pocket at 2 Depth to Rock - Interpreted from End of Report Gravity Data iv, I I...REDUCTION DMAHTC obtained the basic observations for the new stations and reduced them to Simple Bouguer Anomalies (SBA) as described in Appendix A1.0

  1. Development of new experimental platform 'MARS'-Multiple Artificial-gravity Research System-to elucidate the impacts of micro/partial gravity on mice.

    PubMed

    Shiba, Dai; Mizuno, Hiroyasu; Yumoto, Akane; Shimomura, Michihiko; Kobayashi, Hiroe; Morita, Hironobu; Shimbo, Miki; Hamada, Michito; Kudo, Takashi; Shinohara, Masahiro; Asahara, Hiroshi; Shirakawa, Masaki; Takahashi, Satoru

    2017-09-07

    This Japan Aerospace Exploration Agency project focused on elucidating the impacts of partial gravity (partial g) and microgravity (μg) on mice using newly developed mouse habitat cage units (HCU) that can be installed in the Centrifuge-equipped Biological Experiment Facility in the International Space Station. In the first mission, 12 C57BL/6 J male mice were housed under μg or artificial earth-gravity (1 g). Mouse activity was monitored daily via downlinked videos; μg mice floated inside the HCU, whereas artificial 1 g mice were on their feet on the floor. After 35 days of habitation, all mice were returned to the Earth and processed. Significant decreases were evident in femur bone density and the soleus/gastrocnemius muscle weights of μg mice, whereas artificial 1 g mice maintained the same bone density and muscle weight as mice in the ground control experiment, in which housing conditions in the flight experiment were replicated. These data indicate that these changes were particularly because of gravity. They also present the first evidence that the addition of gravity can prevent decreases in bone density and muscle mass, and that the new platform 'MARS' may provide novel insights on the molecular-mechanisms regulating biological processes controlled by partial g/μg.

  2. Validation of the EGSIEM combined monthly GRACE gravity fields

    NASA Astrophysics Data System (ADS)

    Li, Zhao; van Dam, Tonie; Chen, Qiang; Weigelt, Matthias; Güntner, Andreas; Jäggi, Adrian; Meyer, Ulrich; Jean, Yoomin; Altamimi, Zuheir; Rebischung, Paul

    2016-04-01

    Observations indicate that global warming is affecting the water cycle. Here in Europe predictions are for more frequent high precipitation events, wetter winters, and longer and dryer summers. The consequences of these changes include the decreasing availability of fresh water resources in some regions as well as flooding and erosion of coastal and low-lying areas in other regions. These weather related effects impose heavy costs on society and the economy. We cannot stop the immediate effects global warming on the water cycle. But there may be measures that we can take to mitigate the costs to society. The Horizon2020 supported project, European Gravity Service for Improved Emergency Management (EGSIEM), will add value to EO observations of variations in the Earth's gravity field. In particular, the EGSIEM project will interpret the observations of gravity field changes in terms of changes in continental water storage. The project team will develop tools to alert the public water storage conditions could indicate the onset of regional flooding or drought. As part of the EGSIEM project, a combined GRACE gravity product is generated, using various monthly GRACE solutions from associated processing centers (ACs). Since each AC follows a set of common processing standards but applies its own independent analysis method, the quality, robustness, and reliability of the monthly combined gravity fields should be significantly improved as compared to any individual solution. In this study, we present detailed and updated comparisons of the combined EGSIEM GRACE gravity product with GPS position time series, hydrological models, and existing GRACE gravity fields. The GPS residuals are latest REPRO2 station position residuals, obtained by rigorously stacking the IGS Repro 2 , daily solutions, estimating, and then restoring the annual and semi-annual signals.

  3. Exobiology research on Space Station Freedom

    NASA Technical Reports Server (NTRS)

    Huntington, J. L.; Stratton, D. M.; Scattergood, T. W.

    1995-01-01

    The Gas-Grain Simulation Facility (GGSF) is a multidisciplinary experiment laboratory being developed by NASA at Ames Research Center for delivery to Space Station Freedom in 1998. This facility will employ the low-gravity environment of the Space Station to enable aerosol experiments of much longer duration than is possible in any ground-based laboratory. Studies of fractal aggregates that are impossible to sustain on Earth will also be enabled. Three research areas within exobiology that will benefit from the GGSF are described here. An analysis of the needs of this research and of other suggested experiments has produced a list of science requirements which the facility design must accommodate. A GGSF design concept developed in the first stage of flight hardware development to meet these requirements is also described.

  4. GRACILE: a comprehensive climatology of atmospheric gravity wave parameters based on satellite limb soundings

    NASA Astrophysics Data System (ADS)

    Ern, Manfred; Trinh, Quang Thai; Preusse, Peter; Gille, John C.; Mlynczak, Martin G.; Russell, James M., III; Riese, Martin

    2018-04-01

    Gravity waves are one of the main drivers of atmospheric dynamics. The spatial resolution of most global atmospheric models, however, is too coarse to properly resolve the small scales of gravity waves, which range from tens to a few thousand kilometers horizontally, and from below 1 km to tens of kilometers vertically. Gravity wave source processes involve even smaller scales. Therefore, general circulation models (GCMs) and chemistry climate models (CCMs) usually parametrize the effect of gravity waves on the global circulation. These parametrizations are very simplified. For this reason, comparisons with global observations of gravity waves are needed for an improvement of parametrizations and an alleviation of model biases. We present a gravity wave climatology based on atmospheric infrared limb emissions observed by satellite (GRACILE). GRACILE is a global data set of gravity wave distributions observed in the stratosphere and the mesosphere by the infrared limb sounding satellite instruments High Resolution Dynamics Limb Sounder (HIRDLS) and Sounding of the Atmosphere using Broadband Emission Radiometry (SABER). Typical distributions (zonal averages and global maps) of gravity wave vertical wavelengths and along-track horizontal wavenumbers are provided, as well as gravity wave temperature variances, potential energies and absolute momentum fluxes. This global data set captures the typical seasonal variations of these parameters, as well as their spatial variations. The GRACILE data set is suitable for scientific studies, and it can serve for comparison with other instruments (ground-based, airborne, or other satellite instruments) and for comparison with gravity wave distributions, both resolved and parametrized, in GCMs and CCMs. The GRACILE data set is available as supplementary data at https://doi.org/10.1594/PANGAEA.879658.

  5. Recent results on modelling the spatial and temporal structure of the Earth's gravity field.

    PubMed

    Moore, P; Zhang, Q; Alothman, A

    2006-04-15

    The Earth's gravity field plays a central role in sea-level change. In the simplest application a precise gravity field will enable oceanographers to capitalize fully on the altimetric datasets collected over the past decade or more by providing a geoid from which absolute sea-level topography can be recovered. However, the concept of a static gravity field is now redundant as we can observe temporal variability in the geoid due to mass redistribution in or on the total Earth system. Temporal variability, associated with interactions between the land, oceans and atmosphere, can be investigated through mass redistributions with, for example, flow of water from the land being balanced by an increase in ocean mass. Furthermore, as ocean transport is an important contributor to the mass redistribution the time varying gravity field can also be used to validate Global Ocean Circulation models. This paper will review the recent history of static and temporal gravity field recovery, from the 1980s to the present day. In particular, mention will be made of the role of satellite laser ranging and other space tracking techniques, satellite altimetry and in situ gravity which formed the basis of gravity field determination until the last few years. With the launch of Challenging Microsatellite Payload and Gravity and Circulation Experiment (GRACE) our knowledge of the spatial distribution of the Earth's gravity field is taking a leap forward. Furthermore, GRACE is now providing insight into temporal variability through 'monthly' gravity field solutions. Prior to this data we relied on satellite tracking, Global Positioning System and geophysical models to give us insight into the temporal variability. We will consider results from these methodologies and compare them to preliminary results from the GRACE mission.

  6. Ground Reaction Forces During Reduced Gravity Running in Parabolic Flight.

    PubMed

    Cavanagh, Peter; Rice, Andrea; Glauberman, Molly; Sudduth, Amanda; Cherones, Arien; Davis, Shane; Lewis, Michael; Hanson, Andrea; Wilt, Grier

    2017-08-01

    Treadmills have been employed as both a form of exercise and a countermeasure to prevent changes in the musculoskeletal system on almost all NASA missions and many Russian missions since the early Space Shuttle flights. It is possible that treadmills may also be part of exercise programs on future Mars missions and that they may be a component of exercise facilities in lunar or Martian habitats. In order to determine if the ambient gravity on these destinations will provide osteogenic effects while performing exercise on a treadmill, ground reactions forces (GRFs) were measured on eight subjects (six women and two men) running at 6 mph during parabolic flight in Martian and lunar gravity conditions. On average, stride length increased as gravity decreased. The first and second peaks of the GRFs decreased by 0.156 and 0.196 bodyweights, respectively, per 1/10 g change in ambient gravity. Based on comparisons with previously measured GRF during loaded treadmill running on the International Space Station, we conclude that unloaded treadmill running under lunar and Martian conditions during exploration missions is not likely to be an osteo-protective exercise.Cavanagh P, Rice A, Glauberman M, Sudduth A, Cherones A, Davis S, Lewis M, Hanson A, Wilt G. Ground reaction forces during reduced gravity running in parabolic flight. Aerosp Med Hum Perform. 2017; 88(8):730-736.

  7. Effect of gravity on vestibular neural development

    NASA Technical Reports Server (NTRS)

    Ross, M. D.; Tomko, D. L.

    1998-01-01

    The timing, molecular basis, and morphophysiological and behavioral consequences of the interaction between external environment and the internal genetic pool that shapes the nervous system over a lifetime remain important questions in basic neuroscientific research. Space station offers the opportunity to study this interaction over several life cycles in a variety of organisms. This short review considers past work in altered gravity, particularly on the vestibular system, as the basis for proposing future research on space station, and discusses the equipment necessary to achieve goals. It is stressed that, in keeping with the international investment being made in this research endeavor, both the questions asked and the technologies to be developed should be bold. Advantage must be taken of this unique research environment to expand the frontiers of neuroscience. Copyright 1998 Published by Elsevier Science B.V.

  8. Social factors in space station interiors

    NASA Technical Reports Server (NTRS)

    Cranz, Galen; Eichold, Alice; Hottes, Klaus; Jones, Kevin; Weinstein, Linda

    1987-01-01

    Using the example of the chair, which is often written into space station planning but which serves no non-cultural function in zero gravity, difficulties in overcoming cultural assumptions are discussed. An experimental approach is called for which would allow designers to separate cultural assumptions from logistic, social and psychological necessities. Simulations, systematic doubt and monitored brainstorming are recommended as part of basic research so that the designer will approach the problems of space module design with a complete program.

  9. Fluid/gravity correspondence for massive gravity

    NASA Astrophysics Data System (ADS)

    Pan, Wen-Jian; Huang, Yong-Chang

    2016-11-01

    In this paper, we investigate the fluid/gravity correspondence in the framework of massive Einstein gravity. Treating the gravitational mass terms as an effective energy-momentum tensor and utilizing the Petrov-like boundary condition on a timelike hypersurface, we find that the perturbation effects of massive gravity in bulk can be completely governed by the incompressible Navier-Stokes equation living on the cutoff surface under the near horizon and nonrelativistic limits. Furthermore, we have concisely computed the ratio of dynamical viscosity to entropy density for two massive Einstein gravity theories, and found that they still saturate the Kovtun-Son-Starinets (KSS) bound.

  10. Non-Newtonian gravity or gravity anomalies?

    NASA Technical Reports Server (NTRS)

    Rubincam, David P.; Chao, B. Fong; Schatten, Kenneth H.; Sager, William W.

    1988-01-01

    Geophysical measurements of G differ from laboratory values, indicating that gravity may be non-Newtonian. A spherical harmonic formulation is presented for the variation of (Newtonian) gravity inside the Earth. Using the GEM-10B Earth Gravitational Field Model, it is shown that long-wavelength gravity anomalies, if not corrected, may masquerade as non-Newtonian gravity by providing significant influences on experimental observation of delta g/delta r and G. An apparent contradiction in other studies is also resolved: i.e., local densities appear in equations when average densities of layers seem to be called for.

  11. International Space Station Crew Return Vehicle: X-38. Educational Brief.

    ERIC Educational Resources Information Center

    National Aeronautics and Space Administration, Washington, DC.

    The International Space Station (ISS) will provide the world with an orbiting laboratory that will have long-duration micro-gravity experimentation capability. The crew size for this facility will depend upon the crew return capability. The first crews will consist of three astronauts from Russia and the United States. The crew is limited to three…

  12. Effects of Gravity, Microgravity or Microgravity Simulation on Early Mammalian Development.

    PubMed

    Ruden, Douglas M; Bolnick, Alan; Awonuga, Awoniyi; Abdulhasan, Mohammed; Perez, Gloria; Puscheck, Elizabeth E; Rappolee, Daniel A

    2018-06-11

    Plant and animal life forms evolved mechanisms for sensing and responding to gravity on Earth where homeostatic needs require responses. The lack of gravity, such as in the International Space Station (ISS), causes acute, intra-generational changes in the quality of life. These include maintaining calcium levels in bone, maintaining muscle tone, and disturbances in the vestibular apparatus in the ears. These problems decrease work efficiency and quality of life of humans not only during microgravity exposures but also after return to higher gravity on Earth or destinations such as Mars or the Moon. It has been hypothesized that lack of gravity during mammalian development may cause prenatal, postnatal and transgenerational effects that conflict with the environment, especially if the developing organism and its progeny are returned, or introduced de novo, into the varied gravity environments mentioned above. Although chicken and frog pregastrulation development, and plant root development, have profound effects due to orientation of cues by gravity-sensing mechanisms and responses, mammalian development is not typically characterized as gravity-sensing. Although no effects of microgravity simulation (MGS) on mouse fertilization were observed in two reports, negative effects of MGS on early mammalian development after fertilization and before gastrulation are presented in four reports that vary with the modality of MGS. This review will analyze the positive and negative mammalian early developmental outcomes, and enzymatic and epigenetic mechanisms known to mediate developmental responses to simulated microgravity on Earth and microgravity during spaceflight experiments. We will update experimental techniques that have already been developed or need to be developed for zero gravity molecular, cellular, and developmental biology experiments.

  13. Measurement and Characterization of the Acceleration Environment on Board the Space Station

    NASA Technical Reports Server (NTRS)

    Baugher, Charles R. (Editor)

    1990-01-01

    This workshop provides a comprehensive overview of the work and status of each of these areas to provide a basis for establishing a systematic approach to the challenge of avoiding these difficulties during the Space Station era of materials experimentation. The discussions were arranged in the order of: the scientific understanding of the requirements for a micro-gravity environment, a history of acceleration measurements on spacecraft, the state of accelerometer technology, and the current understanding of the predicted Space Station environment.

  14. International Space Station Node 1 is moved for leak test

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Node 1, the first element for the International Space Station, and attached Pressurized Mating Adapter-1 continue with prelaunch preparation activities at KSC's Space Station Processing Facility. Node 1 is a connecting passageway to the living and working areas of the space station. The node is seen here being moved into the Shuttle payload transportation canister, where the doors will be closed for a two-week leak check. The node was moved to the canister from the element rotation stand, or test stand, where it underwent an interim weight and center of gravity determination. The final determination is planned to be performed prior to transporting Node 1 to the launch pad. Node 1 is scheduled to fly on STS-88.

  15. International Space Station Node 1 is moved for leak test

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Node 1, the first U.S. element for the International Space Station, and attached Pressurized Mating Adapter-1 continue with prelaunch preparation activities at KSC's Space Station Processing Facility. Node 1 is a connecting passageway to the living and working areas of the space station. The node and PMA-1 are being removed from the element rotation stand, or test stand, where they underwent an interim weight and center of gravity determination. (The final determination is planned to be performed prior to transporting Node 1 to the launch pad.) Now the node is being moved to the Shuttle payload transportation canister, where the doors will be closed for a two-week leak check. Node 1 is scheduled to fly on STS-88.

  16. Space stations: Living in zero gravity, developmental task for psychologists and space environmental experts

    NASA Technical Reports Server (NTRS)

    Ludwig, E.

    1984-01-01

    The recent advances in the psychological aspects of space station design are discussed, including the impact of the increase in awareness of both the public in general as well as space environmental experts of the importance of psychological factors when designing space stations and training astronauts.

  17. International Space Station (ISS)

    NASA Image and Video Library

    2001-02-10

    Cosmonaut Yuri P. Gidzenko, Expedition One Soyuz commander, stands near the hatch leading from the Unity node into the newly-attached Destiny laboratory aboard the International Space Station (ISS). The Node 1, or Unity, serves as a cornecting passageway to Space Station modules. The U.S.-built Unity module was launched aboard the Orbiter Endeavour (STS-88 mission) on December 4, 1998, and connected to Zarya, the Russian-built Functional Cargo Block (FGB). The U.S. Laboratory (Destiny) module is the centerpiece of the ISS, where science experiments will be performed in the near-zero gravity in space. The Destiny Module was launched aboard the Space Shuttle Orbiter Atlantis (STS-98 mission) on February 7, 2001. The aluminum module is 8.5 meters (28 feet) long and 4.3 meters (14 feet) in diameter. The laboratory consists of three cylindrical sections and two endcones with hatches that will be mated to other station components. A 50.9-centimeter- (20-inch-) diameter window is located on one side of the center module segment. This pressurized module is designed to accommodate pressurized payloads. It has a capacity of 24 rack locations, and payload racks will occupy 13 locations especially designed to support experiments.

  18. Easy Absolute Values? Absolutely

    ERIC Educational Resources Information Center

    Taylor, Sharon E.; Mittag, Kathleen Cage

    2015-01-01

    The authors teach a problem-solving course for preservice middle-grades education majors that includes concepts dealing with absolute-value computations, equations, and inequalities. Many of these students like mathematics and plan to teach it, so they are adept at symbolic manipulations. Getting them to think differently about a concept that they…

  19. Estimating Gravity Biases with Wavelets in Support of a 1-cm Accurate Geoid Model

    NASA Astrophysics Data System (ADS)

    Ahlgren, K.; Li, X.

    2017-12-01

    Systematic errors that reside in surface gravity datasets are one of the major hurdles in constructing a high-accuracy geoid model at high resolutions. The National Oceanic and Atmospheric Administration's (NOAA) National Geodetic Survey (NGS) has an extensive historical surface gravity dataset consisting of approximately 10 million gravity points that are known to have systematic biases at the mGal level (Saleh et al. 2013). As most relevant metadata is absent, estimating and removing these errors to be consistent with a global geopotential model and airborne data in the corresponding wavelength is quite a difficult endeavor. However, this is crucial to support a 1-cm accurate geoid model for the United States. With recently available independent gravity information from GRACE/GOCE and airborne gravity from the NGS Gravity for the Redefinition of the American Vertical Datum (GRAV-D) project, several different methods of bias estimation are investigated which utilize radial basis functions and wavelet decomposition. We estimate a surface gravity value by incorporating a satellite gravity model, airborne gravity data, and forward-modeled topography at wavelet levels according to each dataset's spatial wavelength. Considering the estimated gravity values over an entire gravity survey, an estimate of the bias and/or correction for the entire survey can be found and applied. In order to assess the accuracy of each bias estimation method, two techniques are used. First, each bias estimation method is used to predict the bias for two high-quality (unbiased and high accuracy) geoid slope validation surveys (GSVS) (Smith et al. 2013 & Wang et al. 2017). Since these surveys are unbiased, the various bias estimation methods should reflect that and provide an absolute accuracy metric for each of the bias estimation methods. Secondly, the corrected gravity datasets from each of the bias estimation methods are used to build a geoid model. The accuracy of each geoid model

  20. Goce and Its Role in Combined Global High Resolution Gravity Field Determination

    NASA Astrophysics Data System (ADS)

    Fecher, T.; Pail, R.; Gruber, T.

    2013-12-01

    Combined high-resolution gravity field models serve as a mandatory basis to describe static and dynamic processes in system Earth. Ocean dynamics can be modeled referring to a high-accurate geoid as reference surface, solid earth processes are initiated by the gravity field. Also geodetic disciplines such as height system determination depend on high-precise gravity field information. To fulfill the various requirements concerning resolution and accuracy, any kind of gravity field information, that means satellite as well as terrestrial and altimetric gravity field observations have to be included in one combination process. A key role is here reserved for GOCE observations, which contribute with its optimal signal content in the long to medium wavelength part and enable a more accurate gravity field determination than ever before especially in areas, where no high-accurate terrestrial gravity field observations are available, such as South America, Asia or Africa. For our contribution we prepare a combined high-resolution gravity field model up to d/o 720 based on full normal equation including recent GOCE, GRACE and terrestrial / altimetric data. For all data sets, normal equations are set up separately, relative weighted to each other in the combination step and solved. This procedure is computationally challenging and can only be performed using super computers. We put special emphasis on the combination process, for which we modified especially our procedure to include GOCE data optimally in the combination. Furthermore we modified our terrestrial/altimetric data sets, what should result in an improved outcome. With our model, in which we included the newest GOCE TIM4 gradiometry results, we can show how GOCE contributes to a combined gravity field solution especially in areas of poor terrestrial data coverage. The model is validated by independent GPS leveling data in selected regions as well as computation of the mean dynamic topography over the oceans

  1. Effects of background gravity stimuli on gravity-controlled behavior

    NASA Technical Reports Server (NTRS)

    Mccoy, D. F.

    1976-01-01

    Physiological and developmental effects of altered gravity were researched. The stimulus properties of gravity have been found to possess reinforcing and aversive properties. Experimental approaches taken, used animals placed into fields of artificial gravity, in the form of parabolic or spiral centrifuges. Gravity preferences were noted and it was concluded that the psychophysics of gravity and background factors which support these behaviors should be further explored.

  2. Ideal Gas with a Varying (Negative Absolute) Temperature: an Alternative to Dark Energy?

    NASA Astrophysics Data System (ADS)

    Saha, Subhajit; Mondal, Anindita; Corda, Christian

    2018-02-01

    The present work is an attempt to investigate whether the evolutionary history of the Universe from the offset of inflation can be described by assuming the cosmic fluid to be an ideal gas with a specific gas constant but a varying negative absolute temperature (NAT). The motivation of this work is to search for an alternative to the "exotic" and "supernatural" dark energy (DE). In fact, the NAT works as an "effective quintessence" and there is need to deal neither with exotic matter like DE nor with modified gravity theories. For the sake of completeness, we release some clarifications on NATs in Section 3 of the paper.

  3. Absolutely relative or relatively absolute: violations of value invariance in human decision making.

    PubMed

    Teodorescu, Andrei R; Moran, Rani; Usher, Marius

    2016-02-01

    Making decisions based on relative rather than absolute information processing is tied to choice optimality via the accumulation of evidence differences and to canonical neural processing via accumulation of evidence ratios. These theoretical frameworks predict invariance of decision latencies to absolute intensities that maintain differences and ratios, respectively. While information about the absolute values of the choice alternatives is not necessary for choosing the best alternative, it may nevertheless hold valuable information about the context of the decision. To test the sensitivity of human decision making to absolute values, we manipulated the intensities of brightness stimuli pairs while preserving either their differences or their ratios. Although asked to choose the brighter alternative relative to the other, participants responded faster to higher absolute values. Thus, our results provide empirical evidence for human sensitivity to task irrelevant absolute values indicating a hard-wired mechanism that precedes executive control. Computational investigations of several modelling architectures reveal two alternative accounts for this phenomenon, which combine absolute and relative processing. One account involves accumulation of differences with activation dependent processing noise and the other emerges from accumulation of absolute values subject to the temporal dynamics of lateral inhibition. The potential adaptive role of such choice mechanisms is discussed.

  4. Biological research on a Space Station

    NASA Technical Reports Server (NTRS)

    Krikorian, A. D.; Johnson, Catherine C.

    1990-01-01

    A Space Station can provide reliable, long duration access to ug environments for basic and applied biological research. The uniqueness of access to near-weightless environments to probe fundamental questions of significance to gravitational and Space biologists can be exploited from many vantage points. Access to centrifuge facilities that can provide 1 g and hypo-g controls will permit identification of gravity-dependent or primary effects. Understanding secondary effects of the ug environment as well will allow a fuller exploitation of the Space environment.

  5. Is it possible that a gravity increase of 20 μGal yr-1 in southern Tibet comes from a wide-range density increase?

    NASA Astrophysics Data System (ADS)

    Yi, Shuang; Wang, Qiuyu; Sun, Wenke

    2016-02-01

    With absolute gravimetric observations from 2010 to 2013 in the southern Tibet, Chen et al. (2016) reported a gravity increase of up to 20 μGal/yr and concluded that it is possible if there was a density increase in a disk range of 580 km in diameter. Here we used observations from the gravity satellites Gravity Recovery and Climate Experiment (GRACE) over 12 years to evaluate whether the model was practical, because a mass accumulation in such a large spatial range is well within the detectability ability of GRACE. The gravity trend based on their model is orders of magnitude larger than the GRACE observation, thus negating its conclusions. We then evaluated contributions from seasonal variation, lakes, glaciers, rivers, precipitation, and snowfall and concluded that these factors cannot cause such a large gravity signal. Finally, we discussed some possible explanations for the gravity increase of 40 μGal in two years.

  6. Myosin heavy chain expression in rodent skeletal muscle: effects of exposure to zero gravity

    NASA Technical Reports Server (NTRS)

    Haddad, F.; Herrick, R. E.; Adams, G. R.; Baldwin, K. M.

    1993-01-01

    This study ascertained the effects of 9 days of zero gravity on the relative (percentage of total) and calculated absolute (mg/muscle) content of isomyosin expressed in both antigravity and locomotor skeletal muscle of ground control (CON) and flight-exposed (FL) rats. Results showed that although there were no differences in body weight between FL and CON animals, a significant reduction in muscle mass occurred in the vastus intermedius (VI) (P < 0.05) but not in the vastus lateralis (VL) or the tibialis anterior. Both total muscle protein and myofibril protein content were not different between the muscle regions examined in the FL and CON groups. In the VI, there were trends for reductions in the relative content of type I and IIa myosin heavy chains (MHCs) that were offset by increases in the relative content of both type IIb and possibly type IIx MHC protein (P > 0.05). mRNA levels were consistent with this pattern (P < 0.05). The same pattern held true for the red region of the VL as examined at both the protein and mRNA level (P < 0.05). When the atrophy process was examined, there were net reductions in the absolute content of both type I and IIa MHCs that were offset by calculated increases in type IIb MHC in both VI and red VL. Collectively, these findings suggest that there are both absolute and relative changes occurring in MHC expression in the "red" regions of antigravity skeletal muscle during exposure to zero gravity that could affect muscle function.

  7. Space agriculture in micro- and hypo-gravity: A comparative study of soil hydraulics and biogeochemistry in a cropping unit on Earth, Mars, the Moon and the space station

    NASA Astrophysics Data System (ADS)

    Maggi, Federico; Pallud, Céline

    2010-12-01

    Increasing interest is developing towards soil-based agriculture as a long-term bioregenerative life support during space and planetary explorations. Contrary to hydroponics and aeroponics, soil-based cropping would offer an effective approach to sustain food and oxygen production, decompose organic wastes, sequester carbon dioxide, and filter water. However, the hydraulics and biogeochemical functioning of soil systems exposed to gravities lower than the Earth's are still unknown. Since gravity is crucial in driving water flow, hypogravity will affect nutrient and oxygen transport in the liquid and gaseous phases, and could lead to suffocation of microorganisms and roots, and emissions of toxic gases. A highly mechanistic model coupling soil hydraulics and nutrient biogeochemistry previously tested on soils on Earth ( g=9.806 m s -2) is used to highlight the effects of gravity on the functioning of cropping units on Mars (0.38 g), the Moon (0.16 g), and in the international space station (ISS, nearly 0 g). For each scenario, we have compared the net leaching of water, the leaching of NH 3, NH 4+, NO 2- and NO 3- solutes, the emissions of NH 3, CO 2, N 2O, NO and N 2 gases, the concentrations profiles of O 2, CO 2 and dissolved organic carbon (DOC) in soil, the pH, and the dynamics of various microbial functional groups within the root zone against the same control variables in the soil under terrestrial gravity. The response of the soil ecodynamics was relatively linear; gravitational accelerations lower than the Earth's resulted in 90-100% lower water leaching rates, 95-100% lower nutrient leaching rates, and lower emissions of NH 3 and NO gases (80-95% and 30-40%, respectively). Lower N loss through leaching resulted in 60-100% higher concentration of the microbial biomass, but did not alter the vertical stratification of the microbial functional groups with respect to the stratification on Earth. However, the higher biomass concentration produced higher

  8. GRAV-D Part II : Examining Airborne Gravity Processing Assumptions With an Aim Towards Producing a Better Gravimetric Geoid

    NASA Astrophysics Data System (ADS)

    Theresa, D. M.; Vicki, C.; Dan, R.; Dru, S.

    2008-12-01

    The primary objective of the GRAV-D (Gravity for the Redefinition of the American Vertical Datum) project is to redefine the American vertical datum by using an improved gravimetric geoid. This will be partially accomplished through an extensive airborne gravity measurement campaign, focusing first on the land/water interface (and later on interior areas) of the US and its holdings. This airborne campaign is designed specifically to capture intermediate wavelength gravity information by flying at high altitudes (35,000 ft, ~10 km) with a 10 km line spacing. The intermediate wavelengths captured by airborne gravity data are complementary to ground and satellite gravity data. Combining the GRAV-D airborne gravity data with the Gravity Recovery and Climate Experiment (GRACE) satellite gravity field will allow existing terrestrial data sets to be corrected for bias and trend problems. Ultimately, all three types of data can then be merged into a single accurate representation of the gravity field. Typically, the airborne gravity data reduction process is used to produce free-air anomalies for geological/geophysical applications that require more limited accuracy and precision than do geodetic applications. Thus we re-examine long-standing data reduction simplifications and assumptions with an aim toward improving both the accuracy and precision of airborne gravity data before their inclusion into a gravimetric geoid. The data reduction process is tested on a 400 km x 500 km airborne gravity survey in southern Alaska (in the vicinity of Anchorage) collected in the summer of 2008 as part of the GRAV-D project. Potential improvements in processing come from examining the impacts of various GPS processing schemes on free-air gravity results and re-considering all assumptions in standard airborne gravity processing methods, especially those that might introduce bias into absolute gravity levels.

  9. Determination of shuttle orbiter center of gravity from flight measurements

    NASA Technical Reports Server (NTRS)

    Hinson, E. W.; Nicholson, J. Y.; Blanchard, R. C.

    1991-01-01

    Flight measurements of pitch, yaw, and roll rates and the resultant rotationally induced linear accelerations during three orbital maneuvers on Shuttle mission space transportation system (STS) 61-C were used to calculate the actual orbiter center-of-gravity location. The calculation technique reduces error due to lack of absolute calibration of the accelerometer measurements and compensates for accelerometer temperature bias and for the effects of gravity gradient. Accuracy of the technique was found to be limited by the nonrandom and asymmetrical distribution of orbiter structural vibration at the accelerometer mounting location. Fourier analysis of the vibration was performed to obtain the power spectral density profiles which show magnitudes in excess of 10(exp 4) ug (sup 2)/Hz for the actual vibration and over 500 ug (sup 2)/Hz for the filtered accelerometer measurements. The data from this analysis provide a characterization of the Shuttle acceleration environment which may be useful in future studies related to accelerometer system application and zero-g investigations or processes.

  10. Illinois, Indiana, and Ohio Magnetic and Gravity Maps and Data: A Website for Distribution of Data

    USGS Publications Warehouse

    Daniels, David L.; Kucks, Robert P.; Hill, Patricia L.

    2008-01-01

    This web site gives the results of a USGS project to acquire the best available, public-domain, aeromagnetic and gravity data in the United States and merge these data into uniform, composite grids for each state. The results for the three states, Illinois, Indiana, and Ohio are presented here in one site. Files of aeromagnetic and gravity grids and images are available for these states for downloading. In Illinois, Indiana, and Ohio, 19 magnetic surveys have been knit together to form a single digital grid and map. And, a complete Bouguer gravity anomaly grid and map was generated from 128,227 gravity station measurements in and adjacent to Illinois, Indiana, and Ohio. In addition, a map shows the location of the aeromagnetic surveys, color-coded to the survey flight-line spacing. This project was supported by the Mineral Resource Program of the USGS.

  11. Interpolation of Superconducting Gravity Observations Using Least-Squares Collocation Method

    NASA Astrophysics Data System (ADS)

    Habel, Branislav; Janak, Juraj

    2014-05-01

    A pre-processing of the gravity data measured by superconducting gravimeter involves removing of spikes, offsets and gaps. Their presence in observations can limit the data analysis and degrades the quality of obtained results. Short data gaps are filling by theoretical signal in order to get continuous records of gravity. It requires the accurate tidal model and eventually atmospheric pressure at the observed site. The poster presents a design of algorithm for interpolation of gravity observations with a sampling rate of 1 min. Novel approach is based on least-squares collocation which combines adjustment of trend parameters, filtering of noise and prediction. It allows the interpolation of missing data up to a few hours without necessity of any other information. Appropriate parameters for covariance function are found using a Bayes' theorem by modified optimization process. Accuracy of method is improved by the rejection of outliers before interpolation. For filling of longer gaps the collocation model is combined with theoretical tidal signal for the rigid Earth. Finally, the proposed method was tested on the superconducting gravity observations at several selected stations of Global Geodynamics Project. Testing demonstrates its reliability and offers results comparable with the standard approach implemented in ETERNA software package without necessity of an accurate tidal model.

  12. A new lunar absolute control point: established by images from the landing camera on Chang'e-3

    NASA Astrophysics Data System (ADS)

    Wang, Fen-Fei; Liu, Jian-Jun; Li, Chun-Lai; Ren, Xin; Mu, Ling-Li; Yan, Wei; Wang, Wen-Rui; Xiao, Jing-Tao; Tan, Xu; Zhang, Xiao-Xia; Zou, Xiao-Duan; Gao, Xing-Ye

    2014-12-01

    The establishment of a lunar control network is one of the core tasks in selenodesy, in which defining an absolute control point on the Moon is the most important step. However, up to now, the number of absolute control points has been very sparse. These absolute control points have mainly been lunar laser ranging retroreflectors, whose geographical location can be observed by observations on Earth and also identified in high resolution lunar satellite images. The Chang'e-3 (CE-3) probe successfully landed on the Moon, and its geographical location has been monitored by an observing station on Earth. Since its positional accuracy is expected to reach the meter level, the CE-3 landing site can become a new high precision absolute control point. We use a sequence of images taken from the landing camera, as well as satellite images taken by CE-1 and CE-2, to identify the location of the CE-3 lander. With its geographical location known, the CE-3 landing site can be established as a new absolute control point, which will effectively expand the current area of the lunar absolute control network by 22%, and can greatly facilitate future research in the field of lunar surveying and mapping, as well as selenodesy.

  13. Pre-integrated structures for Space Station Freedom

    NASA Technical Reports Server (NTRS)

    Cruz, Jonathan N.; Monell, Donald W.; Mutton, Philip; Troutman, Patrick A.

    1991-01-01

    An in-space construction (erectable) approach to assembling Freedom is planned but the increasing complexity of the station design along with a decrease in shuttle capability over the past several years has led to an assembly sequence that requires more resources (EVA, lift, volume) than the shuttle can provide given a fixed number of flights. One way to address these issues is to adopt a pre-integrated approach to assembling Freedom. A pre-integrated approach combines station primary structure and distributed systems into discrete sections that are assembled and checked out on the ground. The section is then launched as a single structural entity on the shuttle and attached to the orbiting station is then launched as a single structural entity on the shuttle and attached to the orbiting station with a minimum of EVA. The feasibility of a pre-integrated approach to assembling Freedon is discussed. The structural configuration, packaging, and shuttle integration of discrete pre-integrated elements for Freedom assembly are discussed. It is shown that the pre-integrated approach to assembly reduces EVA and increases shuttle margin with respect to mass, volume, and center of gravity limits when compared to the baseline Freedom assembly sequence.

  14. Light and gravity signals synergize in modulating plant development

    PubMed Central

    Vandenbrink, Joshua P.; Kiss, John Z.; Herranz, Raul; Medina, F. Javier

    2014-01-01

    Tropisms are growth-mediated plant movements that help plants to respond to changes in environmental stimuli. The availability of water and light, as well as the presence of a constant gravity vector, are all environmental stimuli that plants sense and respond to via directed growth movements (tropisms). The plant response to gravity (gravitropism) and the response to unidirectional light (phototropism) have long been shown to be interconnected growth phenomena. Here, we discuss the similarities in these two processes, as well as the known molecular mechanisms behind the tropistic responses. We also highlight research done in a microgravity environment in order to decouple two tropisms through experiments carried out in the absence of a significant unilateral gravity vector. In addition, alteration of gravity, especially the microgravity environment, and light irradiation produce important effects on meristematic cells, the undifferentiated, highly proliferating, totipotent cells which sustain plant development. Microgravity produces the disruption of meristematic competence, i.e., the decoupling of cell proliferation and cell growth, affecting the regulation of the cell cycle and ribosome biogenesis. Light irradiation, especially red light, mediated by phytochromes, has an activating effect on these processes. Phytohormones, particularly auxin, also are key mediators in these alterations. Upcoming experiments on the International Space Station will clarify some of the mechanisms and molecular players of the plant responses to these environmental signals involved in tropisms and the cell cycle. PMID:25389428

  15. Mass Intrusion at Mount St. Helens (WA) From Temporal Gravity Variations

    NASA Astrophysics Data System (ADS)

    Battaglia, M.; Lisowski, M.; Dzurisin, D.; Poland, M. P.; Schilling, S. P.; Diefenbach, A. K.; Wynn, J.

    2015-12-01

    Repeated high-precision gravity measurements made at Mount St. Helens (WA) have revealed systematic temporal variations in the gravity field several years after the end of the 2004-2008 dome-building eruption. Changes in gravity with respect to a stable reference station 36 km NW of the volcano were measured at 10 sites on the volcanic edifice and at 4 sites far afield (10 to 36 km) from the summit in August 2010, August 2012 and August 2014. After simulating and removing the gravity signal associated with changes in mass of the crater glacier, the local hydrothermal aquifer, and vertical deformation, the residual gravity field observed at sites near the volcano's summit significantly increased with respect to the stable reference site during 2010-2012 (maximum change 48 ± 15 mgal). No significant change was measured during 2012-2014. The pattern of gravity increase is radially symmetrical, with a half-width of about 2.5 km and a point of maximum change centered at the 2004-2008 lava dome. Forward modeling of residual gravity data using the same source geometry, depth, and location as that inferred from geodetic data (a spheroidal source centered 7.5 km beneath the 2004-2008 dome) indicates a mass increase rate of the order of 1011 kg/year. For a reasonable magma density (~2250 kg/m3), the volume rate of magma intrusion beneath the summit region inferred from gravity (~ 0.1 km3/yr) greatly exceeds the volume inferred from inversion of geodetic data (0.001 km3/yr between 2008-2011), suggesting that either magma compressibility or other processes are important aspects of magma storage at Mount St. Helens, or that the data argue for a different source.

  16. First tsunami gravity wave detection in ionospheric radio occultation data

    DOE PAGES

    Coïsson, Pierdavide; Lognonné, Philippe; Walwer, Damian; ...

    2015-05-09

    After the 11 March 2011 earthquake and tsunami off the coast of Tohoku, the ionospheric signature of the displacements induced in the overlying atmosphere has been observed by ground stations in various regions of the Pacific Ocean. We analyze here the data of radio occultation satellites, detecting the tsunami-driven gravity wave for the first time using a fully space-based ionospheric observation system. One satellite of the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) recorded an occultation in the region above the tsunami 2.5 h after the earthquake. The ionosphere was sounded from top to bottom, thus providing themore » vertical structure of the gravity wave excited by the tsunami propagation, observed as oscillations of the ionospheric Total Electron Content (TEC). The observed vertical wavelength was about 50 km, with maximum amplitude exceeding 1 total electron content unit when the occultation reached 200 km height. We compared the observations with synthetic data obtained by summation of the tsunami-coupled gravity normal modes of the Earth/Ocean/atmosphere system, which models the associated motion of the ionosphere plasma. These results provide experimental constraints on the attenuation of the gravity wave with altitude due to atmosphere viscosity, improving the understanding of the propagation of tsunami-driven gravity waves in the upper atmosphere. They demonstrate that the amplitude of the tsunami can be estimated to within 20% by the recorded ionospheric data.« less

  17. Space Station Centrifuge: A Requirement for Life Science Research

    NASA Technical Reports Server (NTRS)

    Smith, Arthur H.; Fuller, Charles A.; Johnson, Catherine C.; Winget, Charles M.

    1992-01-01

    A centrifuge with the largest diameter that can be accommodated on Space Station Freedom is required to conduct life science research in the microgravity environment of space. (This was one of the findings of a group of life scientists convened at the University of California, Davis, by Ames Research Center.) The centrifuge will be used as a research tool to understand how gravity affects biological processes; to provide an on-orbit one-g control; and to assess the efficacy of using artificial gravity to counteract the deleterious biological effect of space flight. The rationale for the recommendation and examples of using ground-based centrifugation for animal and plant acceleration studies are presented. Included are four appendixes and an extensive bibliography of hypergravity studies.

  18. Post-Flight Back Pain Following International Space Station Missions: Evaluation of Spaceflight Risk Factors

    NASA Technical Reports Server (NTRS)

    Laughlin, Mitzi S.; Murray, Jocelyn D.; Wear, Mary L.; Van Baalen, Mary

    2016-01-01

    Back pain during spaceflight has often been attributed to the lengthening of the spinal column due to the absence of gravity during both short and long-duration missions. Upon landing and re-adaptation to gravity, the spinal column reverts back to its original length thereby causing some individuals to experience pain and muscular spasms, while others experience no ill effects. With International Space Station (ISS) missions, cases of back pain and injury are more common post-flight, but little is known about the potential risk factors.

  19. Earth System Data Records of Mass Transport from Time-Variable Gravity Data

    NASA Astrophysics Data System (ADS)

    Zlotnicki, V.; Talpe, M.; Nerem, R. S.; Landerer, F. W.; Watkins, M. M.

    2014-12-01

    Satellite measurements of time variable gravity have revolutionized the study of Earth, by measuring the ice losses of Greenland, Antarctica and land glaciers, changes in groundwater including unsustainable losses due to extraction of groundwater, the mass and currents of the oceans and their redistribution during El Niño events, among other findings. Satellite measurements of gravity have been made primarily by four techniques: satellite tracking from land stations using either lasers or Doppler radio systems, satellite positioning by GNSS/GPS, satellite to satellite tracking over distances of a few hundred km using microwaves, and through a gravity gradiometer (radar altimeters also measure the gravity field, but over the oceans only). We discuss the challenges in the measurement of gravity by different instruments, especially time-variable gravity. A special concern is how to bridge a possible gap in time between the end of life of the current GRACE satellite pair, launched in 2002, and a future GRACE Follow-On pair to be launched in 2017. One challenge in combining data from different measurement systems consists of their different spatial and temporal resolutions and the different ways in which they alias short time scale signals. Typically satellite measurements of gravity are expressed in spherical harmonic coefficients (although expansions in terms of 'mascons', the masses of small spherical caps, has certain advantages). Taking advantage of correlations among spherical harmonic coefficients described by empirical orthogonal functions and derived from GRACE data it is possible to localize the otherwise coarse spatial resolution of the laser and Doppler derived gravity models. This presentation discusses the issues facing a climate data record of time variable mass flux using these different data sources, including its validation.

  20. International Space Station -- Fluids and Combustion Facility

    NASA Technical Reports Server (NTRS)

    2000-01-01

    The Fluids and Combustion Facility (FCF) is a modular, multi-user facility to accommodate microgravity science experiments on board Destiny, the U.S. Laboratory Module for the International Space Station (ISS). The FCF will be a permanet facility aboard the ISS, and will be capable of accommodating up to ten science investigations per year. It will support the NASA Science and Technology Research Plans for the International Space Station (ISS) which require sustained systematic research of the effects of reduced gravity in the areas of fluid physics and combustion science. From left to right are the Combustion Integrated Rack, the Shared Rack, and the Fluids Integrated Rack. The FCF is being developed by the Microgravity Science Division (MSD) at the NASA Glenn Research Center. (Photo Credit: NASA/Marshall Space Flight Center)

  1. Coseismic Gravity and Displacement Signatures Induced by the 2013 Okhotsk Mw8.3 Earthquake

    PubMed Central

    Zhang, Guoqing; Shen, Wenbin; Xu, Changyi; Zhu, Yiqing

    2016-01-01

    In this study, Gravity Recovery and Climate Experiment (GRACE) RL05 data from January 2003 to October 2014 were used to extract the coseismic gravity changes induced by the 24 May 2013 Okhotsk Mw8.3 deep-focus earthquake using the difference and least square fitting methods. The gravity changes obtained from GRACE data agreed well with those from dislocation theory in both magnitude and spatial pattern. Positive and negative gravity changes appeared on both sides of the epicenter. The positive signature appeared on the western side, and the peak value was approximately 0.4 microgal (1 microgal = 10−8 m/s2), whereas on the eastern side, the gravity signature was negative, and the peak value was approximately −1.1 microgal. It demonstrates that deep-focus earthquakes Mw ≤ 8.5 are detectable by GRACE observations. Moreover, the coseismic displacements of 20 Global Positioning System (GPS) stations on the Earth’s surface were simulated using an elastic dislocation theory in a spherical earth model, and the results are consistent with the GPS results, especially the near-field results. We also estimated the gravity contributions from the coseismic vertical displacements and density changes, analyzed the proportion of these two gravity change factors (based on an elastic dislocation theory in a spherical earth model) in this deep-focus earthquake. The gravity effect from vertical displacement is four times larger than that caused by density redistribution. PMID:27598158

  2. Coseismic Gravity and Displacement Signatures Induced by the 2013 Okhotsk Mw8.3 Earthquake.

    PubMed

    Zhang, Guoqing; Shen, Wenbin; Xu, Changyi; Zhu, Yiqing

    2016-09-01

    In this study, Gravity Recovery and Climate Experiment (GRACE) RL05 data from January 2003 to October 2014 were used to extract the coseismic gravity changes induced by the 24 May 2013 Okhotsk Mw8.3 deep-focus earthquake using the difference and least square fitting methods. The gravity changes obtained from GRACE data agreed well with those from dislocation theory in both magnitude and spatial pattern. Positive and negative gravity changes appeared on both sides of the epicenter. The positive signature appeared on the western side, and the peak value was approximately 0.4 microgal (1 microgal = 10(-8) m/s²), whereas on the eastern side, the gravity signature was negative, and the peak value was approximately -1.1 microgal. It demonstrates that deep-focus earthquakes Mw ≤ 8.5 are detectable by GRACE observations. Moreover, the coseismic displacements of 20 Global Positioning System (GPS) stations on the Earth's surface were simulated using an elastic dislocation theory in a spherical earth model, and the results are consistent with the GPS results, especially the near-field results. We also estimated the gravity contributions from the coseismic vertical displacements and density changes, analyzed the proportion of these two gravity change factors (based on an elastic dislocation theory in a spherical earth model) in this deep-focus earthquake. The gravity effect from vertical displacement is four times larger than that caused by density redistribution.

  3. Conceptual design for the space station Freedom modular combustion facility

    NASA Technical Reports Server (NTRS)

    1989-01-01

    A definition study and conceptual design for a combustion science facility that will be located in the Space Station Freedom's baseline U.S. Laboratory module is being performed. This modular, user-friendly facility, called the Modular Combustion Facility, will be available for use by industry, academic, and government research communities in the mid-1990's. The Facility will support research experiments dealing with the study of combustion and its byproducts. Because of the lack of gravity-induced convection, research into the mechanisms of combustion in the absence of gravity will help to provide a better understanding of the fundamentals of the combustion process. The background, current status, and future activities of the effort are covered.

  4. Complete Bouguer gravity anomaly map of the state of Colorado

    USGS Publications Warehouse

    Abrams, Gerda A.

    1993-01-01

    The Bouguer gravity anomaly map is part of a folio of maps of Colorado cosponsored by the National Mineral Resources Assessment Program (NAMRAP) and the National Geologic Mapping Program (COGEOMAP) and was produced to assist in studies of the mineral resource potential and tectonic setting of the State. Previous compilations of about 12,000 gravity stations by Behrendt and Bajwa (1974a,b) are updated by this map. The data was reduced at a 2.67 g/cm3 and the grid contoured at 3 mGal intervals. This map will aid in the mineral resource assessment by indicating buried intrusive complexes, volcanic fields, major faults and shear zones, and sedimentary basins; helping to identify concealed geologic units; and identifying localities that might be hydrothermically altered or mineralized.

  5. Aeolian processes aboard a space station: Saltation and particle trajectory analysis

    NASA Technical Reports Server (NTRS)

    White, B. R.; Greeley, R.; Iversen, J. D.; Leach, R. N.

    1986-01-01

    The Carousel wind tunnel (CWT) proposed to study aeolian processes aboard a space station consists of two concentric rotating drums. The space between the two drums comprises the wind tunnel test section. Differential rates of rotation of the two drums would provide a wind velocity with respect to either drum surface. Preliminary results of measured velocity profiles made in a CWT prototype indicate that the wall bounded boundary layer profiles are suitable to simulate flat plate turbulent boundary layer flow. The two dimensional flat plate Cartesian coordinate equations of motion of a particle moving through the air are explained. In order to assess the suitability of CWT in the analysis of the trajectories of windblown particles, a series of calculations were conducted comparing cases for gravity with those of zero gravity. Results from the calculations demonstrate that a wind tunnel of the carousel design could be fabricted to operate in a space station environment and that experiments could be conducted which would yield significant results contributing to the understanding of the physics of particle dynamics.

  6. Aeolian processes aboard a Space Station: Saltation and particle trajectory analysis

    NASA Technical Reports Server (NTRS)

    White, Bruce R.; Greeley, Ronald; Iversen, James D.; Leach, R. N.

    1987-01-01

    The Carousel Wind Tunnel (CWT) proposed to study aeolian processes aboard a Space Station consists of two concentric rotating drums. The space between the two drums comprises the wind tunnel section. Differential rates of rotation of the two drums would provide a wind velocity with respect to either drum surface. Preliminary results of measured velocity profiles made in a CWT prototype indicate that the wall bounded boundary layer profiles are suitable to simuate flat plate turbulent boundary layer flow. The two dimensional flate plate Cartesian coordinate equations of motion of a particle moving through the air are explained. In order to assess the suitability of CWT in the analysis of the trajectories of windblown particles, a series of calculations were conducted comparing cases for gravity with those of zero gravity. Results from the calculations demonstrate that a wind tunnel of the carousel design could be fabricated to operate in a space station environment and that experiments could be conducted which would yield significant results contributing to the understanding of the physics of particle dynamics.

  7. International Space Station (ISS)

    NASA Image and Video Library

    2001-02-11

    This STS-98 mission photograph shows astronauts Thomas D. Jones (foreground) and Kerneth D. Cockrell floating inside the newly installed Laboratory aboard the International Space Station (ISS). The American-made Destiny module is the cornerstone for space-based research aboard the orbiting platform and the centerpiece of the ISS, where unprecedented science experiments will be performed in the near-zero gravity of space. Destiny will also serve as the command and control center for the ISS. The aluminum module is 8.5-meters (28-feet) long and 4.3-meters (14-feet) in diameter. The laboratory consists of three cylindrical sections and two endcones with hatches that will be mated to other station components. A 50.9-centimeter (20-inch-) diameter window is located on one side of the center module segment. This pressurized module is designed to accommodate pressurized payloads. It has a capacity of 24 rack locations. Payload racks will occupy 15 locations especially designed to support experiments. The Destiny module was built by the Boeing Company under the direction of the Marshall Space Flight Center.

  8. Gravity-dependent differentiation and root coils in Arabidopsis thaliana wild type and phospholipase-A-I knockdown mutant grown on the International Space Station.

    PubMed

    Scherer, G F E; Pietrzyk, P

    2014-01-01

    Arabidopsis roots on 45° tilted agar in 1-g grow in wave-like figures. In addition to waves, formation of root coils is observed in several mutants compromised in gravitropism and/or auxin transport. The knockdown mutant ppla-I-1 of patatin-related phospholipase-A-I is delayed in root gravitropism and forms increased numbers of root coils. Three known factors contribute to waving: circumnutation, gravisensing and negative thigmotropism. In microgravity, deprivation of wild type (WT) and mutant roots of gravisensing and thigmotropism and circumnutation (known to slow down in microgravity, and could potentially lead to fewer waves or increased coiling in both WT and mutant). To resolve this, mutant ppla-I-1 and WT were grown in the BIOLAB facility in the International Space Station. In 1-g, roots of both types only showed waving. In the first experiment in microgravity, the mutant after 9 days formed far more coils than in 1-g but the WT also formed several coils. After 24 days in microgravity, in both types the coils were numerous with slightly more in the mutant. In the second experiment, after 9 days in microgravity only the mutant formed coils and the WT grew arcuated roots. Cell file rotation (CFR) on the mutant root surface in microgravity decreased in comparison to WT, and thus was not important for coiling. Several additional developmental responses (hypocotyl elongation, lateral root formation, cotyledon expansion) were found to be gravity-influenced. We tentatively discuss these in the context of disturbances in auxin transport, which are known to decrease through lack of gravity. © 2013 German Botanical Society and The Royal Botanical Society of the Netherlands.

  9. Absolute biological needs.

    PubMed

    McLeod, Stephen

    2014-07-01

    Absolute needs (as against instrumental needs) are independent of the ends, goals and purposes of personal agents. Against the view that the only needs are instrumental needs, David Wiggins and Garrett Thomson have defended absolute needs on the grounds that the verb 'need' has instrumental and absolute senses. While remaining neutral about it, this article does not adopt that approach. Instead, it suggests that there are absolute biological needs. The absolute nature of these needs is defended by appeal to: their objectivity (as against mind-dependence); the universality of the phenomenon of needing across the plant and animal kingdoms; the impossibility that biological needs depend wholly upon the exercise of the abilities characteristic of personal agency; the contention that the possession of biological needs is prior to the possession of the abilities characteristic of personal agency. Finally, three philosophical usages of 'normative' are distinguished. On two of these, to describe a phenomenon or claim as 'normative' is to describe it as value-dependent. A description of a phenomenon or claim as 'normative' in the third sense does not entail such value-dependency, though it leaves open the possibility that value depends upon the phenomenon or upon the truth of the claim. It is argued that while survival needs (or claims about them) may well be normative in this third sense, they are normative in neither of the first two. Thus, the idea of absolute need is not inherently normative in either of the first two senses. © 2013 John Wiley & Sons Ltd.

  10. Three-dimensional inversion of regional P and S arrival times in the East Aleutians and sources of subduction zone gravity highs

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Abers, G.A.

    1994-03-10

    Free-air gravity highs over forearcs represent a large fraction of the power in the Earth`s anomalous field, yet their origin remains uncertain. Seismic velocities, as indicators of density, are estimated here as a means to compare the relative importance of upper plate sources for the gravity high with sources in the downgoing plate. P and S arrival times for local earthquakes, recorded by a seismic network in the eastern Aleutians, are inverted for three-dimensional velocity structure between the volcanic arc and the downgoing plate. A three-dimensional ray tracing scheme is used to invert the 7974 P and 6764 S arrivalsmore » for seismic velocities and hypocenters of 635 events. One-dimensional inversions show that station P residuals are systematically 0.25 - 0.5 s positive at stations 0-30 km north of the Aleutian volcanic arc, indicating slow material, while residuals at stations 10-30 km south of the arc are 0.1-0.25 s negative. Both features are explained in three-dimensional inversions by velocity variations at depths less than 25-35 km. Tests using a one-dimensional or a two-dimensional slab starting model show that below 100 km depth, velocities are poorly determined and trade off almost completely with hypocenters for earthquakes at these depths. The locations of forearc velocity highs, in the crust of the upper plate, correspond to the location of the gravity high between the trench and volcanic arc. Free-air anomalies, calculated from the three-dimensional velocity inversion result, match observed gravity for a linear density-velocity relationship between 0.1 and 0.3 (Mg m{sup {minus}3})/(km s{sup {minus}1}), when a 50-km-thick slab is included with a density of 0.055{+-}0.005 Mg m{sup {minus}3}. Values outside these ranges do not match the observed gravity. The slab alone contributes one third to one half of the total 75-150 mGal amplitude of the gravity high but predicts a high that is much broader than is observed.« less

  11. Computer-aided controllability assessment of generic manned Space Station concepts

    NASA Technical Reports Server (NTRS)

    Ferebee, M. J.; Deryder, L. J.; Heck, M. L.

    1984-01-01

    NASA's Concept Development Group assessment methodology for the on-orbit rigid body controllability characteristics of each generic configuration proposed for the manned space station is presented; the preliminary results obtained represent the first step in the analysis of these eight configurations. Analytical computer models of each configuration were developed by means of the Interactive Design Evaluation of Advanced Spacecraft CAD system, which created three-dimensional geometry models of each configuration to establish dimensional requirements for module connectivity, payload accommodation, and Space Shuttle berthing; mass, center-of-gravity, inertia, and aerodynamic drag areas were then derived. Attention was also given to the preferred flight attitude of each station concept.

  12. Underwater gravity meter survey of San Francisco and San Pablo bays, California, 1982

    USGS Publications Warehouse

    Childs, Jonathan R.; Beyer, L.A.; McCulloch, D.S.; McHendrie, G.A.; Steele, W.C.

    1983-01-01

    Seafloor gravity measurements were made at 281 bottom stations in San Francisco and San Pablo Bays, California, on a series of lines oriented approximately NNE.. Line spacing was approximately 2.8 km and stations along the lines mere spaced 0.5 to 1.5 km apart, between 0.5 and 1.5 km perpendicular to the axis. Sample Bouguer anomalies in the San Francisco Bay range from -15 to +15 mGals (?0.1 mgal), while anomalies in the San Pablo Bay are consistently negative, ranging from +4.0 to -40.0 mGal (?0.2 mGal).

  13. Gravity Acceleration and Gravity Paradox

    NASA Astrophysics Data System (ADS)

    Hanyongquan, Han; Yuteng, Tang

    2017-10-01

    The magnitude of the gravitational acceleration of the earth is derived from low of universal gravitation. If the size and mass of the gravitational force are proportional to any situation, then the celestial surface gravity is greater than the celestial center near the gravity, and objective facts do not match. Specific derivation method, F = GMm / R2 = mg, g = GM/R2 . c / Ú, G is the gravitational constant, M is the mass of the earth, and finally the g = 9.8 m/s 2 is obtained. We assume that the earth is a standard positive sphere, the earth's volume V = 4 ΠR3/3, assuming that the earth's density is ρ, then M = ρ 4 ΠR3/3 .. c / Ú, the c / Ú into c / Ú get: g = G ρ4 ΠR / 3 .. c / Û, the density of the earth is constant. Careful analysis of the formula c / Û The result of this calculation, we can reach conclusion the gravity acceleration g and the radius of the earth is proportional. In addition to the radius of the Earth c / U the right is constant, That is, the Earth's Gravity acceleration of the outer layer of the earth is greater than the Earth's Gravity acceleration of Inner layer. We are in High School, Huairou District, Beijing, China Author: hanyongquan tangyuteng TEL: 15611860790, 15810953809.

  14. A Bottom Gravity Survey of the Continental Shelf Between Point Lobos and Point Sur, California.

    DTIC Science & Technology

    From an occupation of 68 ocean bottom and 38 land gravity stations between Pt. Lobos and Pt. Sur, California, a complete Bouguer anomaly map was...produced and analyzed. The steps in data reduction leading to the complete Bouguer anomaly field are presented, unique features of which are associated

  15. Research centrifuge accommodations on Space Station Freedom

    NASA Technical Reports Server (NTRS)

    Arno, Roger D.; Horkachuk, Michael J.

    1990-01-01

    Life sciences research using plants and animals on the Space Station Freedom requires the ability to maintain live subjects in a safe and low stress environment for long durations at microgravity and at one g. The need for a centrifuge to achieve these accelerations is evident. Programmatic, technical, and cost considerations currently favor a 2.5 meter diameter centrifuge located either in the end cone of a Space Station Freedom node or in a separate module. A centrifuge facility could support a mix of rodent, plant, and small primate habitats. An automated cage extractor could be used to remove modular habitats in pairs without stopping the main rotor, minimizing the disruption to experiment protocols. The accommodation of such a centrifuge facility on the Space Station represents a significant demand on the crew time, power, data, volume, and logistics capability. It will contribute to a better understanding of the effects of space flight on humans, an understanding of plant growth in space for the eventual production of food, and an understanding of the role of gravity in biological processes.

  16. Gravity field information from Gravity Probe-B

    NASA Technical Reports Server (NTRS)

    Smith, D. E.; Lerch, F. J.; Colombo, O. L.; Everitt, C. W. F.

    1989-01-01

    The Gravity Probe-B Mission will carry the Stanford Gyroscope relativity experiment into orbit in the mid 1990's, as well as a Global Positioning System (GPS) receiver whose tracking data will be used to study the earth gravity field. Estimates of the likely quality of a gravity field model to be derived from the GPS data are presented, and the significance of this experiment to geodesy and geophysics are discussed.

  17. Terrestrial Gravity Fluctuations

    NASA Astrophysics Data System (ADS)

    Harms, Jan

    2015-12-01

    Different forms of fluctuations of the terrestrial gravity field are observed by gravity experiments. For example, atmospheric pressure fluctuations generate a gravity-noise foreground in measurements with super-conducting gravimeters. Gravity changes caused by high-magnitude earthquakes have been detected with the satellite gravity experiment GRACE, and we expect high-frequency terrestrial gravity fluctuations produced by ambient seismic fields to limit the sensitivity of ground-based gravitational-wave (GW) detectors. Accordingly, terrestrial gravity fluctuations are considered noise and signal depending on the experiment. Here, we will focus on ground-based gravimetry. This field is rapidly progressing through the development of GW detectors. The technology is pushed to its current limits in the advanced generation of the LIGO and Virgo detectors, targeting gravity strain sensitivities better than 10-23 Hz-1/2 above a few tens of a Hz. Alternative designs for GW detectors evolving from traditional gravity gradiometers such as torsion bars, atom interferometers, and superconducting gradiometers are currently being developed to extend the detection band to frequencies below 1 Hz. The goal of this article is to provide the analytical framework to describe terrestrial gravity perturbations in these experiments. Models of terrestrial gravity perturbations related to seismic fields, atmospheric disturbances, and vibrating, rotating or moving objects, are derived and analyzed. The models are then used to evaluate passive and active gravity noise mitigation strategies in GW detectors, or alternatively, to describe their potential use in geophysics. The article reviews the current state of the field, and also presents new analyses especially with respect to the impact of seismic scattering on gravity perturbations, active gravity noise cancellation, and time-domain models of gravity perturbations from atmospheric and seismic point sources. Our understanding of

  18. Terrestrial Gravity Fluctuations.

    PubMed

    Harms, Jan

    2015-01-01

    Different forms of fluctuations of the terrestrial gravity field are observed by gravity experiments. For example, atmospheric pressure fluctuations generate a gravity-noise foreground in measurements with super-conducting gravimeters. Gravity changes caused by high-magnitude earthquakes have been detected with the satellite gravity experiment GRACE, and we expect high-frequency terrestrial gravity fluctuations produced by ambient seismic fields to limit the sensitivity of ground-based gravitational-wave (GW) detectors. Accordingly, terrestrial gravity fluctuations are considered noise and signal depending on the experiment. Here, we will focus on ground-based gravimetry. This field is rapidly progressing through the development of GW detectors. The technology is pushed to its current limits in the advanced generation of the LIGO and Virgo detectors, targeting gravity strain sensitivities better than 10 -23 Hz -1/2 above a few tens of a Hz. Alternative designs for GW detectors evolving from traditional gravity gradiometers such as torsion bars, atom interferometers, and superconducting gradiometers are currently being developed to extend the detection band to frequencies below 1 Hz. The goal of this article is to provide the analytical framework to describe terrestrial gravity perturbations in these experiments. Models of terrestrial gravity perturbations related to seismic fields, atmospheric disturbances, and vibrating, rotating or moving objects, are derived and analyzed. The models are then used to evaluate passive and active gravity noise mitigation strategies in GW detectors, or alternatively, to describe their potential use in geophysics. The article reviews the current state of the field, and also presents new analyses especially with respect to the impact of seismic scattering on gravity perturbations, active gravity noise cancellation, and time-domain models of gravity perturbations from atmospheric and seismic point sources. Our understanding of

  19. Inversion of gravity gradient tensor data: does it provide better resolution?

    NASA Astrophysics Data System (ADS)

    Paoletti, V.; Fedi, M.; Italiano, F.; Florio, G.; Ialongo, S.

    2016-04-01

    The gravity gradient tensor (GGT) has been increasingly used in practical applications, but the advantages and the disadvantages of the analysis of GGT components versus the analysis of the vertical component of the gravity field are still debated. We analyse the performance of joint inversion of GGT components versus separate inversion of the gravity field alone, or of one tensor component. We perform our analysis by inspection of the Picard Plot, a Singular Value Decomposition tool, and analyse both synthetic data and gradiometer measurements carried out at the Vredefort structure, South Africa. We show that the main factors controlling the reliability of the inversion are algebraic ambiguity (the difference between the number of unknowns and the number of available data points) and signal-to-noise ratio. Provided that algebraic ambiguity is kept low and the noise level is small enough so that a sufficient number of SVD components can be included in the regularized solution, we find that: (i) the choice of tensor components involved in the inversion is not crucial to the overall reliability of the reconstructions; (ii) GGT inversion can yield the same resolution as inversion with a denser distribution of gravity data points, but with the advantage of using fewer measurement stations.

  20. Delineating the Rattlesnake Springs, New Mexico Watershed Using Precision Gravity Techniques

    NASA Astrophysics Data System (ADS)

    Doser, D. I.; Boykov, N. D.; Baker, M. R.; Kaip, G. M.; Langford, R. P.

    2009-12-01

    Rattlesnake Springs serves as the sole domestic water source for Carlsbad Caverns National Park. The recent development of oil and gas leases and agricultural lands surrounding the springs has led to concern about contamination of the fracture controlled aquifer system. We have conducted a series of precision gravity surveys (station spacing 200 to 300 m in a 4 x 4 km area), combined with other geophysical studies and geologic mapping, to delineate possible fracture systems in the gypsum and carbonate bedrock that feed the spring system. Our combined results suggest several pathways for water to enter the springs. A series of WNW-ESE striking features are apparent in our gravity data that appear to align with relict spring valleys we have mapped to the west of the springs. A self potential survey indicates that water is entering the springs at a shallow level from the northwest direction. However, gravity data also indicate a north-south trending fracture system could be providing a pathway for water to enter from the south. This is consistent with drawdown tests conducted in the 1950’s and 1960’s on irrigation wells located to the south of the springs. The north-south fracture system appears related to a basin bounding fault system observed in the regional gravity data.

  1. Gravity field of the Western Weddell Sea: Comparison of airborne gravity and Geosat derived gravity

    NASA Technical Reports Server (NTRS)

    Bell, R. E.; Brozena, J. M.; Haxby, W. F.; Labrecque, J. L.

    1989-01-01

    Marine gravity surveying in polar regions was typically difficult and costly, requiring expensive long range research vessels and ice-breakers. Satellite altimetry can recover the gravity field in these regions where it is feasible to survey with a surface vessel. Unfortunately, the data collected by the first global altimetry mission, Seasat, was collected only during the austral winter, producing a very poor quality gravitational filed for the southern oceans, particularly in the circum-Antarctic regions. The advent of high quality airborne gravity (Brozena, 1984; Brozena and Peters, 1988; Bell, 1988) and the availability of satellite altimetry data during the austral summer (Sandwell and McAdoo, 1988) has allowed the recovery of a free air gravity field for most of the Weddell Sea. The derivation of the gravity field from both aircraft and satellite measurements are briefly reviewed, before presenting along track comparisons and shaded relief maps of the Weddell Sea gravity field based on these two data sets.

  2. Using an instrumented manikin for Space Station Freedom analysis

    NASA Technical Reports Server (NTRS)

    Orr, Linda; Hill, Richard

    1989-01-01

    One of the most intriguing and complex areas of current computer graphics research is animating human figures to behave in a realistic manner. Believable, accurate human models are desirable for many everyday uses including industrial and architectural design, medical applications, and human factors evaluations. For zero-gravity (0-g) spacecraft design and mission planning scenarios, they are particularly valuable since 0-g conditions are difficult to simulate in a one-gravity Earth environment. At NASA/JSC, an in-house human modeling package called PLAID is currently being used to produce animations for human factors evaluation of Space Station Freedom design issues. Presented here is an introductory background discussion of problems encountered in existing techniques for animating human models and how an instrumented manikin can help improve the realism of these models.

  3. User needs, benefits and integration of robotic systems in a space station laboratory

    NASA Technical Reports Server (NTRS)

    Farnell, K. E.; Richard, J. A.; Ploge, E.; Badgley, M. B.; Konkel, C. R.; Dodd, W. R.

    1989-01-01

    The methodology, results and conclusions of the User Needs, Benefits, and Integration Study (UNBIS) of Robotic Systems in the Space Station Microgravity and Materials Processing Facility are summarized. Study goals include the determination of user requirements for robotics within the Space Station, United States Laboratory. Three experiments were selected to determine user needs and to allow detailed investigation of microgravity requirements. A NASTRAN analysis of Space Station response to robotic disturbances, and acceleration measurement of a standard industrial robot (Intelledex Model 660) resulted in selection of two ranges of low gravity manipulation: Level 1 (10-3 to 10-5 G at greater than 1 Hz.) and Level 2 (less than = 10-6 G at 0.1 Hz). This included an evaluation of microstepping methods for controlling stepper motors and concluded that an industrial robot actuator can perform milli-G motion without modification. Relative merits of end-effectors and manipulators were studied in order to determine their ability to perform a range of tasks related to the three low gravity experiments. An Effectivity Rating was established for evaluating these robotic system capabilities. Preliminary interface requirements were determined such that definition of requirements for an orbital flight demonstration experiment may be established.

  4. The mechanics of unrest at Long Valley caldera, California. 2. Constraining the nature of the source using geodetic and micro-gravity data

    USGS Publications Warehouse

    Battaglia, Maurizio; Segall, P.; Roberts, C.

    2003-01-01

    We model the source of inflation of Long Valley caldera by combining geodetic and micro-gravity data. Uplift from GPS and leveling, two-color EDM measurements, and residual gravity change determinations are used to estimate the intrusion geometry, assuming a vertical prolate ellipsoidal source. The U.S. Geological Survey occupied the Long Valley gravity network six times from 1980 to 1985. We reoccupied this network twice, in the summer of 1998 (33 stations), and the summer of 1999 (37 stations). Before gravity data can be used to estimate the density of the intrusion, they must be corrected for the effect of vertical deformation (the free-air effect) and changes in the water table. We use geostatistical techniques to interpolate uplift and water table changes at the gravity stations. The inflation source (a vertical prolate ellipsoid) is located 5.9 km beneath the resurgent dome with an aspect ratio equal to 0.475, a volume change from 1982 to 1999 of 0.136 km3 and a density of around 1700 kg/m3. A bootstrap method was employed to estimate 95% confidence bounds for the parameters of the inflation model. We obtained a range of 0.105-0.187 km3 for the volume change, and 1180-2330 kg/m3 for the density. Our results do not support hydrothermal fluid intrusion as the primary cause of unrest, and confirm the intrusion of silicic magma beneath Long Valley caldera. Failure to account for the ellipsoidal nature of the source biases the estimated source depth by 2.9 km (a 33% increase), the volume change by 0.019 km3 (a 14% increase) and the density by about 1200 kg/m3 (a 40% increase). ?? 2003 Elsevier B.V. All rights reserved.

  5. Joint Inversion of 3d Mt/gravity/magnetic at Pisagua Fault.

    NASA Astrophysics Data System (ADS)

    Bascur, J.; Saez, P.; Tapia, R.; Humpire, M.

    2017-12-01

    This work shows the results of a joint inversion at Pisagua Fault using 3D Magnetotellurics (MT), gravity and regional magnetic data. The MT survey has a poor coverage of study area with only 21 stations; however, it allows to detect a low resistivity zone aligned with the Pisagua Fault trace that it is interpreted as a damage zone. The integration of gravity and magnetic data, which have more dense sampling and coverage, adds more detail and resolution to the detected low resistivity structure and helps to improve the structure interpretation using the resulted models (density, magnetic-susceptibility and electrical resistivity). The joint inversion process minimizes a multiple target function which includes the data misfit, model roughness and coupling norms (crossgradient and direct relations) for all geophysical methods considered (MT, gravity and magnetic). This process is solved iteratively using the Gauss-Newton method which updates the model of each geophysical method improving its individual data misfit, model roughness and the coupling with the other geophysical models. For solving the model updates of magnetic and gravity methods were developed dedicated 3D inversion software codes which include the coupling norms with additionals geophysical parameters. The model update of the 3D MT is calculated using an iterative method which sequentially filters the priority model and the output model of a single 3D MT inversion process for obtaining the resistivity model coupled solution with the gravity and magnetic methods.

  6. Radiological assessment for Space Station Freedom

    NASA Technical Reports Server (NTRS)

    Badhwar, Gautam D.; Hardy, Alva C.; Robbins, Donald E.; Atwell, William

    1993-01-01

    Circumstances have made it necessary to reassess the risks to Space Station Freedom crewmembers that arise from exposure to the space radiation environment. An option is being considered to place it in an orbit similar to that of the Russian Mir space station. This means it would be in a 51.6 deg inclination orbit instead of the previously planned 28.5 deg inclination orbit. A broad range of altitudes is still being considered, although the baseline is a 407 km orbit. In addition, recent data from the Japanese A-bomb survivors has made it necessary for NASA to have the exposure limits reviewed. Preliminary findings of the National Council on Radiation Protection and Measurements indicate that the limits must be significantly reduced. Finally, the Space Station will be a laboratory where effects of long-term zero gravity on human physiology will be studied in detail. It is possible that a few crewmembers will be assigned to as many as three 1-year missions. Thus, their accumulated exposure will exceed 1,000 days. Results of this radiation risk assessment for Space Station Freedom crewmembers finds that females less than 35 years old will be confined to mission assignments where the altitude is less than about 400 km. Slight restrictions may also need to be made for male crewmembers less than 35 years old.

  7. The ecology of microorganisms in a small closed system: Potential benefits and problems for space station

    NASA Technical Reports Server (NTRS)

    Rodgers, E. B.

    1986-01-01

    The inevitble presence on the space station of microorganisms associated with crew members and their environment will have the potential for both benefits and a range of problems including illness and corrosion of materials. This report reviews the literature presenting information about microorganisms pertinent to Environmental Control and Life Support (ECLS) on the space station. The perspective of the report is ecological, viewing the space station as an ecosystem in which biological relationships are affected by factors such as zero gravity and by closure of a small volume of space. Potential sites and activities of microorganisms on the space station and their environmental limits, microbial standards for the space station, monitoring and control methods, effects of space factors on microorganisms, and extraterrestrial contamination are discussed.

  8. Seeking the Light: Gravity Without the Influence of Gravity

    NASA Technical Reports Server (NTRS)

    Sack, Fred; Kern, Volker; Reed, Dave; Etheridge, Guy (Technical Monitor)

    2002-01-01

    All living things sense gravity like humans might sense light or sound. The Biological Research In Canisters (BRIC-14) experiment, explores how moss cells sense and respond to gravity and light. This experiment studies how gravity influences the internal structure of moss cells and seeks to understand the influences of the spaceflight environment on cell growth. This knowledge will help researchers understand the role of gravity in the evolution of cells and life on earth.

  9. Terrestrial gravity data analysis for interim gravity model improvement

    NASA Technical Reports Server (NTRS)

    1987-01-01

    This is the first status report for the Interim Gravity Model research effort that was started on June 30, 1986. The basic theme of this study is to develop appropriate models and adjustment procedures for estimating potential coefficients from terrestrial gravity data. The plan is to use the latest gravity data sets to produce coefficient estimates as well as to provide normal equations to NASA for use in the TOPEX/POSEIDON gravity field modeling program.

  10. A SEA FLOOR GRAVITY SURVEY OF THE SLEIPNER FIELD TO MONITOR CO2 MIGATION

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mark Zumberge

    2003-06-13

    At the Sleipner gas field, excess CO{sub 2} is sequestered and injected underground into a porous saline aquifer 1000 m below the seafloor. A high precision micro-gravity survey was carried out on the seafloor to monitor the injected CO{sub 2}. A repeatability of 5 {micro}Gal in the station averages was observed. This is considerably better than pre-survey expectations. These data will serve as the baseline for time-lapse gravity monitoring of the Sleipner CO{sub 2} injection site. Simple modeling of the first year data give inconclusive results, thus a more detailed approach is needed. Work towards this is underway.

  11. Spacecraft Fire Detection: Smoke Properties and Transport in Low-Gravity

    NASA Technical Reports Server (NTRS)

    Urban, David L.; Ruff, Gary A.; Brooker, John E.; Cleary, Thomas; Yang, Jiann; Mulholland, George; Yuan, Zeng-guang

    2007-01-01

    Results from a recent smoke particle size measurement experiment conducted on the International Space Station (ISS) are presented along with the results from a model of the transport of smoke in the ISS. The experimental results show that, for the materials tested, a substantial portion of the smoke particles are below 500 nm in diameter. The smoke transport model demonstrated that mixing dominates the smoke transport and that consequently detection times are longer than in normal gravity.

  12. Geoid undulation computations at laser tracking stations

    NASA Technical Reports Server (NTRS)

    Despotakis, Vasilios K.

    1987-01-01

    Geoid undulation computations were performed at 29 laser stations distributed around the world using a combination of terrestrial gravity data within a cap of radius 2 deg and a potential coefficient set up to 180 deg. The traditional methods of Stokes' and Meissl's modification together with the Molodenskii method and the modified Sjoberg method were applied. Performing numerical tests based on global error assumptions regarding the terrestrial data and the geopotential set it was concluded that the modified Sjoberg method is the most accurate and promising technique for geoid undulation computations. The numerical computations for the geoid undulations using all the four methods resulted in agreement with the ellipsoidal minus orthometric value of the undulations on the order of 60 cm or better for most of the laser stations in the eastern United States, Australia, Japan, Bermuda, and Europe. A systematic discrepancy of about 2 meters for most of the western United States stations was detected and verified by using two relatively independent data sets. For oceanic laser stations in the western Atlantic and Pacific oceans that have no terrestrial data available, the adjusted GEOS-3 and SEASAT altimeter data were used for the computation of the geoid undulation in a collocation method.

  13. On the impact of topography and building mask on time varying gravity due to local hydrology

    NASA Astrophysics Data System (ADS)

    Deville, S.; Jacob, T.; Chéry, J.; Champollion, C.

    2013-01-01

    We use 3 yr of surface absolute gravity measurements at three sites on the Larzac plateau (France) to quantify the changes induced by topography and the building on gravity time-series, with respect to an idealized infinite slab approximation. Indeed, local topography and buildings housing ground-based gravity measurement have an effect on the distribution of water storage changes, therefore affecting the associated gravity signal. We first calculate the effects of surrounding topography and building dimensions on the gravity attraction for a uniform layer of water. We show that a gravimetric interpretation of water storage change using an infinite slab, the so-called Bouguer approximation, is generally not suitable. We propose to split the time varying gravity signal in two parts (1) a surface component including topographic and building effects (2) a deep component associated to underground water transfer. A reservoir modelling scheme is herein presented to remove the local site effects and to invert for the effective hydrological properties of the unsaturated zone. We show that effective time constants associated to water transfer vary greatly from site to site. We propose that our modelling scheme can be used to correct for the local site effects on gravity at any site presenting a departure from a flat topography. Depending on sites, the corrected signal can exceed measured values by 5-15 μGal, corresponding to 120-380 mm of water using the Bouguer slab formula. Our approach only requires the knowledge of daily precipitation corrected for evapotranspiration. Therefore, it can be a useful tool to correct any kind of gravimetric time-series data.

  14. Compatibility of the Space Station Freedom life sciences research centrifuge with microgravity requirements

    NASA Technical Reports Server (NTRS)

    Hasha, Martin D.

    1990-01-01

    NASA is developing a Life Sciences Centrifuge Facility for Space Station Freedom. In includes a 2.5-meter artificial gravity Bioresearch Centrifuge (BC), which is perhaps the most critical single element in the life sciences space research program. It rotates continuously at precise selectable rates, and utilizes advanced reliable technologies to reduce vibrations. Three disturbance types are analyzed using a current Space Station Freedom dynamic model in the 0.0 to 5.0 Hz range: sinusoidal, random, and transient. Results show that with proper selection of proven design techniques, BC vibrations are compatible with requirements.

  15. Gravity fluctuations induced by magma convection at Kilauea Volcano, Hawai'i

    USGS Publications Warehouse

    Carbone, Daniele; Poland, Michael P.

    2012-01-01

    Convection in magma chambers is thought to play a key role in the activity of persistently active volcanoes, but has only been inferred indirectly from geochemical observations or simulated numerically. Continuous microgravity measurements, which track changes in subsurface mass distribution over time, provide a potential method for characterizing convection in magma reservoirs. We recorded gravity oscillations with a period of ~150 s at two continuous gravity stations at the summit of Kīlauea Volcano, Hawai‘i. The oscillations are not related to inertial accelerations caused by seismic activity, but instead indicate variations in subsurface mass. Source modeling suggests that the oscillations are caused by density inversions in a magma reservoir located ~1 km beneath the east margin of Halema‘uma‘u Crater in Kīlauea Caldera—a location of known magma storage.

  16. Jasminum flexile flower absolute from India--a detailed comparison with three other jasmine absolutes.

    PubMed

    Braun, Norbert A; Kohlenberg, Birgit; Sim, Sherina; Meier, Manfred; Hammerschmidt, Franz-Josef

    2009-09-01

    Jasminum flexile flower absolute from the south of India and the corresponding vacuum headspace (VHS) sample of the absolute were analyzed using GC and GC-MS. Three other commercially available Indian jasmine absolutes from the species: J. sambac, J. officinale subsp. grandiflorum, and J. auriculatum and the respective VHS samples were used for comparison purposes. One hundred and twenty-one compounds were characterized in J. flexile flower absolute, with methyl linolate, benzyl salicylate, benzyl benzoate, (2E,6E)-farnesol, and benzyl acetate as the main constituents. A detailed olfactory evaluation was also performed.

  17. Forced and natural convection in laminar-jet diffusion flames. [normal-gravity, inverted-gravity and zero-gravity flames

    NASA Technical Reports Server (NTRS)

    Haggard, J. B., Jr.

    1981-01-01

    An experimental investigation was conducted on methane, laminar-jet, diffusion flames with coaxial, forced-air flow to examine flame shapes in zero-gravity and in situations where buoyancy aids (normal-gravity flames) or hinders (inverted-gravity flames) the flow velocities. Fuel nozzles ranged in size from 0.051 to 0.305 cm inside radius, while the coaxial, convergent, air nozzle had a 1.4 cm inside radius at the fuel exit plane. Fuel flows ranged from 1.55 to 10.3 cu cm/sec and air flows from 0 to 597 cu cm/sec. A computer program developed under a previous government contract was used to calculate the characteristic dimensions of normal and zero-gravity flames only. The results include a comparison between the experimental data and the computed axial flame lengths for normal gravity and zero gravity which showed good agreement. Inverted-gravity flame width was correlated with the ratio of fuel nozzle radius to average fuel velocity. Flame extinguishment upon entry into weightlessness was studied, and it was found that relatively low forced-air velocities (approximately 10 cm/sec) are sufficient to sustain methane flame combustion in zero gravity. Flame color is also discussed.

  18. Development of a gravity-independent wastewater bioprocessor for advanced life support in space

    NASA Technical Reports Server (NTRS)

    Nashashibi-Rabah, Majda; Christodoulatos, Christos; Korfiatis, George P.; Janes, H. W. (Principal Investigator)

    2005-01-01

    Operation of aerobic biological reactors in space is controlled by a number of challenging constraints, mainly stemming from mass transfer limitations and phase separation. Immobilized-cell packed-bed bioreactors, specially designed to function in the absence of gravity, offer a viable solution for the treatment of gray water generated in space stations and spacecrafts. A novel gravity-independent wastewater biological processor, capable of carbon oxidation and nitrification of high-strength aqueous waste streams, is presented. The system, consisting of a fully saturated pressurized packed bed and a membrane oxygenation module attached to an external recirculation loop, operated continuously for over one year. The system attained high carbon oxidation efficiencies often exceeding 90% and ammonia oxidation reaching approximately 60%. The oxygen supply module relies on hydrophobic, nonporous, oxygen selective membranes, in a shell and tube configuration, for transferring oxygen to the packed bed, while keeping the gaseous and liquid phases separated. This reactor configuration and operating mode render the system gravity-independent and suitable for space applications.

  19. Absolute nuclear material assay

    DOEpatents

    Prasad, Manoj K [Pleasanton, CA; Snyderman, Neal J [Berkeley, CA; Rowland, Mark S [Alamo, CA

    2012-05-15

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  20. Absolute nuclear material assay

    DOEpatents

    Prasad, Manoj K [Pleasanton, CA; Snyderman, Neal J [Berkeley, CA; Rowland, Mark S [Alamo, CA

    2010-07-13

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  1. A generic multi-flex-body dynamics, controls simulation tool for space station

    NASA Technical Reports Server (NTRS)

    London, Ken W.; Lee, John F.; Singh, Ramen P.; Schubele, Buddy

    1991-01-01

    An order (n) multiflex body Space Station simulation tool is introduced. The flex multibody modeling is generic enough to model all phases of Space Station from build up through to Assembly Complete configuration and beyond. Multibody subsystems such as the Mobile Servicing System (MSS) undergoing a prescribed translation and rotation are also allowed. The software includes aerodynamic, gravity gradient, and magnetic field models. User defined controllers can be discrete or continuous. Extensive preprocessing of 'body by body' NASTRAN flex data is built in. A significant aspect, too, is the integrated controls design capability which includes model reduction and analytic linearization.

  2. Superconducting gravity gradiometer for sensitive gravity measurements. I. Theory

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chan, H.A.; Paik, H.J.

    1987-06-15

    Because of the equivalence principle, a global measurement is necessary to distinguish gravity from acceleration of the reference frame. A gravity gradiometer is therefore an essential instrument needed for precision tests of gravity laws and for applications in gravity survey and inertial navigation. Superconductivity and SQUID (superconducting quantum interference device) technology can be used to obtain a gravity gradiometer with very high sensitivity and stability. A superconducting gravity gradiometer has been developed for a null test of the gravitational inverse-square law and space-borne geodesy. Here we present a complete theoretical model of this instrument. Starting from dynamical equations for themore » device, we derive transfer functions, a common mode rejection characteristic, and an error model of the superconducting instrument. Since a gradiometer must detect a very weak differential gravity signal in the midst of large platform accelerations and other environmental disturbances, the scale factor and common mode rejection stability of the instrument are extremely important in addition to its immunity to temperature and electromagnetic fluctuations. We show how flux quantization, the Meissner effect, and properties of liquid helium can be utilized to meet these challenges.« less

  3. Fractional gravity studies on the ISS of sensory mechanisms involved in phototropism

    NASA Astrophysics Data System (ADS)

    Kiss, John Z.; Correll, Melanie; Edelmann, Richard; Millar, Katherine

    The major goals of this research are (1) to better understand cellular mechanisms of pho-totropism in plants and (2) to determine the effects and influence of gravity on light perception in plants. Because of the interfering effect of the strong gravitropic response, microgravity conditions are needed to effectively study phototropism. Experiments performed on the In-ternational Space Station (ISS) were used to explore the mechanisms of both blue-light and red-light-induced phototropism in plants. We utilized the European Modular Cultivation Sys-tem (EMCS), which has environmental controls for plant growth as well as centrifuges for gravity treatments. TROPI-1 (for tropisms) was successfully performed on the ISS during late 2006. We obtained data on seedlings grown in microgravity and discovered a novel positive phototropic response to red light in hypocotyls of seedlings of Arabidopsis thaliana. However, one problem encoun-tered during TROPI-1 was low seed germination due to long storage periods (8 months) in flight hardware. Thus, the originally proposed fractional gravity studies were not performed. TROPI-2 provides an opportunity to regain the results from these important fractional gravity experiments. TROPI-2 experiments will provide a better understanding of how plants integrate sensory input from multiple light and gravity perception systems. This information is important for growing plants on long-term space missions as part of life support systems. The fractional gravity studies contain 0.16g (Moon) and 0.38g (Mars) treatments, so information to be obtained is relevant to exploration objectives

  4. Dualities and emergent gravity: Gauge/gravity duality

    NASA Astrophysics Data System (ADS)

    de Haro, Sebastian

    2017-08-01

    In this paper I develop a framework for relating dualities and emergence: two notions that are close to each other but also exclude one another. I adopt the conception of duality as 'isomorphism', from the physics literature, cashing it out in terms of three conditions. These three conditions prompt two conceptually different ways in which a duality can be modified to make room for emergence; and I argue that this exhausts the possibilities for combining dualities and emergence (via coarse-graining). I apply this framework to gauge/gravity dualities, considering in detail three examples: AdS/CFT, Verlinde's scheme, and black holes. My main point about gauge/gravity dualities is that the theories involved, qua theories of gravity, must be background-independent. I distinguish two senses of background-independence: (i) minimalistic and (ii) extended. I argue that the former is sufficiently strong to allow for a consistent theory of quantum gravity; and that AdS/CFT is background-independent on this account; while Verlinde's scheme best fits the extended sense of background-independence. I argue that this extended sense should be applied with some caution: on pain of throwing the baby (general relativity) out with the bath-water (extended background-independence). Nevertheless, it is an interesting and potentially fruitful heuristic principle for quantum gravity theory construction. It suggests some directions for possible generalisations of gauge/gravity dualities. The interpretation of dualities is discussed; and the so-called 'internal' vs. 'external' viewpoints are articulated in terms of: (i) epistemic and metaphysical commitments; (ii) parts vs. wholes. I then analyse the emergence of gravity in gauge/gravity dualities in terms of the two available conceptualisations of emergence; and I show how emergence in AdS/CFT and in Verlinde's scenario differ from each other. Finally, I give a novel derivation of the Bekenstein-Hawking black hole entropy formula based on

  5. Nonlocal Gravity

    NASA Astrophysics Data System (ADS)

    Mashhoon, Bahram

    2017-05-01

    Relativity theory is based on a postulate of locality, which means that the past history of the observer is not directly taken into account. This book argues that the past history should be taken into account. In this way, nonlocality 1R 2i1nr-in the sense of history dependence-is introduced into relativity theory. The deep connection between inertia and gravitation suggests that gravity could be nonlocal, and in nonlocal gravity the fading gravitational memory of past events must then be taken into account. Along this line of thought, a classical nonlocal generalization of Einstein's theory of gravitation has recently been developed. A significant consequence of this theory is that the nonlocal aspect of gravity appears to simulate dark matter. According to nonlocal gravity theory, what astronomers attribute to dark matter should instead be due to the nonlocality of gravitation. Nonlocality dominates on the scale of galaxies and beyond. Memory fades with time; therefore, the nonlocal aspect of gravity becomes weaker as the universe expands. The implications of nonlocal gravity are explored in this book for gravitational lensing, gravitational radiation, the gravitational physics of the Solar System and the internal dynamics of nearby galaxies, as well as clusters of galaxies. This approach is extended to nonlocal Newtonian cosmology, where the attraction of gravity fades with the expansion of the universe. Thus far, scientists have only compared some of the consequences of nonlocal gravity with astronomical observations.

  6. Venus gravity: Summary and coming events

    NASA Technical Reports Server (NTRS)

    Sjogren, W. L.

    1992-01-01

    The first significant dataset to provide local measures of venusian gravity field variations was that acquired from the Pioneer Venus Orbiter (PVO) during the 1979-1981 period. These observations were S-band Doppler radio signals from the orbiting spacecraft received at Earth-based tracking stations. Early reductions of these data were performed using two quite different techniques. Estimates of the classical spherical harmonics were made to various degrees and orders up to 10. At that time, solutions of much higher degree and order were very difficult due to computer limitations. These reductions, because of low degree and order, revealed only the most prominent features with poor spatial resolution and very reduced peak amplitudes.

  7. Simulation and preparation of surface EVA in reduced gravity at the Marseilles Bay subsea analogue sites

    NASA Astrophysics Data System (ADS)

    Weiss, P.; Gardette, B.; Chirié, B.; Collina-Girard, J.; Delauze, H. G.

    2012-12-01

    Extravehicular activity (EVA) of astronauts during space missions is simulated nowadays underwater in neutral buoyancy facilities. Certain aspects of weightlessness can be reproduced underwater by adding buoyancy to a diver-astronaut, therefore exposing the subject to the difficulties of working without gravity. Such tests were done at the COMEX' test pool in Marseilles in the 1980s to train for a French-Russian mission to the MIR station, for the development of the European HERMES shuttle and the COLUMBUS laboratory. However, space agencies are currently studying missions to other destinations than the International Space Station in orbit, such as the return to the Moon, NEO (near-Earth objects) or Mars. All these objects expose different gravities: Moon has one sixth of Earth's gravity, Mars has a third of Earth's gravity and asteroids have virtually no surface gravity; the astronaut "floats" above the ground. The preparation of such missions calls for a new concept in neutral buoyancy training, not on man-made structures, but on natural terrain, underwater, to simulate EVA operations such as sampling, locomotion or even anchoring in low gravity. Underwater sites can be used not only to simulate the reduced gravity that astronauts will experience during their field trips, also human factors like stress are more realistically reproduced in such environment. The Bay of Marseille hosts several underwater sites that can be used to simulate various geologic morphologies, such as sink-holes which can be used to simulate astronaut descends into craters, caves where explorations of lava tubes can be trained or monolithic rock structures that can be used to test anchoring devices (e.g., near Earth objects). Marseilles with its aerospace and maritime/offshore heritage hosts the necessary logistics and expertise that is needed to perform such simulations underwater in a safe manner (training of astronaut-divers in local test pools, research vessels, subsea robots and

  8. Whole-Body Movements in Long-Term Weightlessness: Hierarchies of the Controlled Variables Are Gravity-Dependent.

    PubMed

    Casellato, Claudia; Pedrocchi, Alessandra; Ferrigno, Giancarlo

    2017-01-01

    Switching between contexts affects the mechanisms underlying motion planning, in particular it may entail reranking the variables to be controlled in defining the motor solutions. Three astronauts performed multiple sessions of whole-body pointing, in normogravity before launch, in prolonged weightlessness onboard the International Space Station, and after return. The effect of gravity context on kinematic and dynamic components was evaluated. Hand trajectory was gravity independent; center-of-mass excursion was highly variable within and between subjects. The body-environment effort exchange, expressed as inertial ankle momentum, was systematically lower in weightlessness than in normogravity. After return on Earth, the system underwent a rapid 1-week readaptation. The study indicates that minimizing the control effort is given greater weight when optimizing the motor plan in weightlessness compared to normogravity: the hierarchies of the controlled variables are gravity dependent.

  9. Coupled Gravity and Elevation Measurement of Ice Sheet Mass Change

    NASA Technical Reports Server (NTRS)

    Jezek, K. C.; Baumgartner, F.

    2005-01-01

    During June 2003, we measured surface gravity at six locations about a glaciological measurement site located on the South-central Greenland Ice. We operated a GPS unit for 90 minutes at each site -the unit was operated simultaneously with a base station unit in Sondrestrom Fjord so as to enable differential, post-processing of the data. We installed an aluminum, accumulation-rate-pole at each site. The base section of the pole also served as the mount for the GPS antenna. Two gravimeters were used simultaneously at each site. Measurements were repeated at each site with at time lapse of at least 50 minutes. We measured snow physical properties in two shallow pits The same measurement sites were occupied in 1981 and all were part of a hexagonal network of geodetic and glaciological measurements established by The Ohio State University in 1980. Additional gravity observations were acquired at three of the sites in 1993 and 1995. Gravity data were collected in conjunction with Doppler satellite measurements of position and elevation in 1981 and global positioning system measurements subsequently. The use of satellite navigation techniques permitted reoccupation of the same sites in each year to within a few 10 s of meters or better. After detrending the gravity data, making adjustments for tides and removing the residual effects of local spatial gradients in gravity, we observe an average secular decrease in gravity of about 0.01 milligal/year, but with tenths of milligal variations about the mean trend. The trend is consistent with a nearly linear increase in surface elevation of between 7 to 10 c d y r (depending on location) as measured by repeated airborne laser altimeter, surface Doppler satellite and GPS elevation measurements. Differences between the residual gravity anomalies after free air correction may be attributable to local mass changes. This project is a collaboration between the Byrd Polar Research Center of the Ohio State University and the Arctic

  10. Exhaustive testing of recent oceanic and Earth tidal models using combination of tide gravity data from GGP and ICET data banks

    NASA Astrophysics Data System (ADS)

    Kopaev, A.; Ducarme, B.

    2003-04-01

    We have used the most recent oceanic tidal models e.g. FES’99/02, GOT’00, CSR’4, NAO’99 and TPXO’5/6 for tidal gravity loading computations using LOAD’97 software. Resulting loading vectors were compared against each other in different regions located at different distances from the sea coast. Results indicate good coincidence for majority of models at the distances larger than 100-200 km, excluding some regions where mostly CSR’4 and TPXO have problems. Outlying models were rejected for this regions and mean loading vectors have been calculated for more than 200 tidal gravity stations from GGP and ICET data banks, representing state of the art of tidal loading correction. Corresponding errors in d-factors and phase lags are generally smaller than 0.1 % resp. 0.05o, that means that we do not have the real troubles with loading corrections and more attention should be applied to the calibration values and phase lag determination accuracies. Corrected values agree with DDW model values very well (within 0.2 %) for majority of GGP stations, whereas some of very good (Chinese network mainly) ICET tidal gravity stations clearly demonstrate statistically significant (up to 0.5 %) anomalies that seems not connected either with calibration troubles or loading problems. Various possible reasons including instrumental and geophysical will be presented and discussed.

  11. Gravity Anomalies and Isostasy Deduced From New Dense Gravimetry Around the Tsangpo Gorge, Tibet

    NASA Astrophysics Data System (ADS)

    Fu, Guangyu; She, Yawen

    2017-10-01

    We built the first dense gravity network including 107 stations around the Tsangpo Gorge, Tibet, one of the hardest places in the world to reach, and conducted a gravity and hybrid GPS observation campaign in 2016. We computed the Bouguer gravity anomalies (BGAs) and free-air gravity anomalies (FGAs) and increased the resolution of the FGAs by merging the in situ data with EIGEN-6C4 gravity model data. The BGAs around the Tsangpo Gorge are in general negative and gradually decrease from south (-360 mGal) to north (-480 mGal). They indicate a uniformly dipping Moho around the Tsangpo Gorge that sinks from south to north at an angle of 12°. We introduced a method to compute the vertical tectonic stress of the lithosphere, a quantitative expression of isostasy, using BGA and terrain data, and applied it to the area around the Tsangpo Gorge. We found that the lithosphere of the upstream of the Tsangpo Gorge is roughly in an isostatic state, but the lithosphere of the downstream exhibits vertical tectonic stress of 50 MPa, which indicates the loss of a large amount of surface material. This result does not support the deduction of the valley bottom before uplift of the Tsangpo Gorge by Wang et al. (2014).

  12. Conceptual design for the Space Station Freedom fluid physics/dynamics facility

    NASA Technical Reports Server (NTRS)

    Thompson, Robert L.; Chucksa, Ronald J.; Omalley, Terence F.; Oeftering, Richard C.

    1993-01-01

    A study team at NASA's Lewis Research Center has been working on a definition study and conceptual design for a fluid physics and dynamics science facility that will be located in the Space Station Freedom's baseline U.S. Laboratory module. This modular, user-friendly facility, called the Fluid Physics/Dynamics Facility, will be available for use by industry, academic, and government research communities in the late 1990's. The Facility will support research experiments dealing with the study of fluid physics and dynamics phenomena. Because of the lack of gravity-induced convection, research into the mechanisms of fluids in the absence of gravity will help to provide a better understanding of the fundamentals of fluid processes. This document has been prepared as a final version of the handout for reviewers at the Fluid Physics/Dynamics Facility Assessment Workshop held at Lewis on January 24 and 25, 1990. It covers the background, current status, and future activities of the Lewis Project Study Team effort. It is a revised and updated version of a document entitled 'Status Report on the Conceptual Design for the Space Station Fluid Physics/Dynamics Facility', dated January 1990.

  13. Non-linear motions in reprocessed GPS station position time series

    NASA Astrophysics Data System (ADS)

    Rudenko, Sergei; Gendt, Gerd

    2010-05-01

    Global Positioning System (GPS) data of about 400 globally distributed stations obtained at time span from 1998 till 2007 were reprocessed using GFZ Potsdam EPOS (Earth Parameter and Orbit System) software within International GNSS Service (IGS) Tide Gauge Benchmark Monitoring (TIGA) Pilot Project and IGS Data Reprocessing Campaign with the purpose to determine weekly precise coordinates of GPS stations located at or near tide gauges. Vertical motions of these stations are used to correct the vertical motions of tide gauges for local motions and to tie tide gauge measurements to the geocentric reference frame. Other estimated parameters include daily values of the Earth rotation parameters and their rates, as well as satellite antenna offsets. The solution GT1 derived is based on using absolute phase center variation model, ITRF2005 as a priori reference frame, and other new models. The solution contributed also to ITRF2008. The time series of station positions are analyzed to identify non-linear motions caused by different effects. The paper presents the time series of GPS station coordinates and investigates apparent non-linear motions and their influence on GPS station height rates.

  14. Procedures and results related to the direct determination of gravity anomalies from satellite and terrestrial gravity data

    NASA Technical Reports Server (NTRS)

    Rapp, R. H.

    1974-01-01

    The equations needed for the incorporation of gravity anomalies as unknown parameters in an orbit determination program are described. These equations were implemented in the Geodyn computer program which was used to process optical satellite observations. The arc dependent parameter unknowns, 184 unknown 15 deg and coordinates of 7 tracking stations were considered. Up to 39 arcs (5 to 7 days) involving 10 different satellites, were processed. An anomaly solution from the satellite data and a combination solution with 15 deg terrestrial anomalies were made. The limited data samples indicate that the method works. The 15 deg anomalies from various solutions and the potential coefficients implied by the different solutions are reported.

  15. Eastern US crustal thickness estimates from spectral analysis and inversion of onshore Bouguer gravity anaomalies

    NASA Astrophysics Data System (ADS)

    Dybus, W.; Benoit, M. H.; Ebinger, C. J.

    2011-12-01

    The crustal thickness beneath much of the eastern half of the US is largely unconstrained. Though there have been several controlled source seismic surveys of the region, many of these studies suffer from rays that turn in the crust above the Moho, resulting in somewhat ambiguous crustal thickness values. Furthermore, the broadband seismic station coverage east of the Mississippi has been limited, and most of the region remains largely understudied. In this study, we estimated the depth to the Moho using both spectral analysis and inversion of Bouguer gravity anomalies. We systematically estimated depths to lithospheric density contrasts from radial power spectra of Bouguer gravity within 100 km X 100 km windows eastward from the Mississippi River to the Atlantic Coast, and northward from North Carolina to Maine. The slopes and slope breaks in the radial power spectra were computed using an automated algorithm. The slope values for each window were visually inspected and then used to estimate the depth to the Moho and other lithospheric density contrasts beneath each windowed region. Additionally, we performed a standard Oldenburg-Parker inversion for lithospheric density contrasts using various reference depths and density contrasts that are realistic for the different physiographic provinces in the Eastern US. Our preliminary results suggest that the gravity-derived Moho depths are similar to those found using seismic data, and that the crust is relatively thinner (~28-33 km) than expected in beneath the Piedmont region (~35-40 km). Given the relative paucity of seismic data in the eastern US, analysis of onshore gravity data is a valuable tool for interpolating between seismic stations.

  16. Seasonal Variation of Wave Activities near the Mesopause Region Observed at King Sejong Station (62.22°S, 58.78°W), Antarctica

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Lee, C.; Kim, J.; Jee, G.; Won, Y.; Wu, D. L.

    2012-12-01

    We have analyzed neutral wind data obtained from a VHF meteor radar at King Sejong Station (KSS), Antarctica to investigate wave activities in the altitude region of 80 - 100 km over the Antarctic vortex boundary. The seasonal behavior of semidiurnal tides is generally consistent with the prediction of GSWM (Global Scale Wave Model) except for the altitude region above ~96 km. The gravity wave activities inferred from variances of neutral winds show very similar seasonal characteristics to the semidiurnal tides, implying that there is a close interaction between the gravity wave and tide. Although the seasonal behaviors of the wind variance as an indicator of the gravity wave activity are consistent with those observed at the adjacent Rothera station, the magnitude of the variances at KSS is much larger above the mesopause, especially from May through September, than those at Rothera. The Aura Microwave Limb Sounder (MLS) satellite observations also confirmed the enhancement of gravity wave activity during the same period near the tip of Antarctic Peninsula, where KSS is located. The observed large wind variances at KSS may imply that the atmospheric conditions near the Antarctic vortex are very effective for generation of the gravity waves that propagate to the upper atmosphere.

  17. Lovelock gravities from Born-Infeld gravity theory

    NASA Astrophysics Data System (ADS)

    Concha, P. K.; Merino, N.; Rodríguez, E. K.

    2017-02-01

    We present a Born-Infeld gravity theory based on generalizations of Maxwell symmetries denoted as Cm. We analyze different configuration limits allowing to recover diverse Lovelock gravity actions in six dimensions. Further, the generalization to higher even dimensions is also considered.

  18. The Microgravity Science Glovebox (MSG), a Resource for Gravity-Dependent Phenomena Research on the International Space Station (ISS)

    NASA Technical Reports Server (NTRS)

    Spivey, Reggie A.; Jeter, Linda B.; Vonk, Chris

    2007-01-01

    The Microgravity Science Glovebox (MSG) is a double rack facility aboard the International Space Station (ISS) designed for gravity-dependent phenomena investigation handling. The MSG has been operating in the ISS US Laboratory Module since July 2002. The MSG facility provides an enclosed working area for investigation manipulation and observation in the ISS. The MSG s unique design provides two levels of containment to protect the ISS crew from hazardous operations. Research investigations operating inside the MSG are provided a large 255 liter work volume, 1000 watts of dc power via a versatile supply interface (120,28, +/-12, and 5 Vdc), 1000 watts of cooling capability, video and data recording and real time downlink, ground commanding capabilities, access to ISS Vacuum Exhaust and Vacuum Resource Systems, and gaseous nitrogen supply. With these capabilities, the MSG is an ideal platform for research required to advance the technology readiness levels (TRL) needed for the Crew Exploration Vehicle and the Exploration Initiative. Areas of research that will benefit from investigations in the MSG include thermal management, fluid physics, spacecraft fire safety, materials science, combustion and reacting control systems, in situ fabrication and repair, and advanced life support technologies. This paper will provide a detailed explanation of the MSG facility, a synopsis of the research that has already been accomplished in the MSG, an overview of investigations planning to operate in the MSG, and possible augmentations that can be added to the MSG facility to further enhance the resources provided to investigations.

  19. The Microgravity Science Glovebox (MSG), a Resource for Gravity-Dependent Phenomena Research on the International Space Station (ISS)

    NASA Technical Reports Server (NTRS)

    Spivey, Reggie A.; Jeter, Linda B.; Vonk, Chris

    2007-01-01

    The Microgravity Science Glovebox (MSG) is a double rack facility aboard the International Space Station (ISS) designed for gravity-dependent phenomena investigation handling. The MSG has been operating in the ISS US Laboratory Module since July 2002. The MSG facility provides an enclosed working area for investigation manipulation and observation in the ISS. The MSG's unique design provides two levels of containment to protect the ISS crew from hazardous operations. Research investigations operating inside the MSG are provided a large 255 liter work volume, 1000 watts of dc power via a versatile supply interface (120,28, plus or minus 12, and 5 Vdc), 1000 watts of cooling capability, video and data recording and real time downlink, ground commanding capabilities, access to ISS Vacuum Exhaust' and Vacuum Resource 'Systems, and gaseous nitrogen supply. With these capabilities, the MSG is an ideal platform for research required to advance the technology readiness levels (TRL) needed for the Crew Exploration Vehicle and the Exploration Initiative. Areas of research that will benefit from investigations in the MSG include thermal management, fluid physics, spacecraft fire safety, materials science, combustion and reacting control systems, in situ fabrication and repair, and advanced life support technologies. This paper will provide a detailed explanation of the MSG facility, a synopsis of the research that has already been accomplished in the MSG, an overview of investigations planning to operate in the MSG, and possible augmentations that can be added to-the MSG facility to further enhance the resources provided to investigations.

  20. Human Biomechanical and Cardiopulmonary Responses to Partial Gravity - A Systematic Review.

    PubMed

    Richter, Charlotte; Braunstein, Bjoern; Winnard, Andrew; Nasser, Mona; Weber, Tobias

    2017-01-01

    The European Space Agency has recently announced to progress from low Earth orbit missions on the International Space Station to other mission scenarios such as exploration of the Moon or Mars. Therefore, the Moon is considered to be the next likely target for European human space explorations. Compared to microgravity (μg), only very little is known about the physiological effects of exposure to partial gravity (μg < partial gravity <1 g). However, previous research studies and experiences made during the Apollo missions comprise a valuable source of information that should be taken into account when planning human space explorations to reduced gravity environments. This systematic review summarizes the different effects of partial gravity (0.1-0.4 g) on the human musculoskeletal, cardiovascular and respiratory systems using data collected during the Apollo missions as well as outcomes from terrestrial models of reduced gravity with either 1 g or microgravity as a control. The evidence-based findings seek to facilitate decision making concerning the best medical and exercise support to maintain astronauts' health during future missions in partial gravity. The initial search generated 1,323 publication hits. Out of these 1,323 publications, 43 studies were included into the present analysis and relevant data were extracted. None of the 43 included studies investigated long-term effects. Studies investigating the immediate effects of partial gravity exposure reveal that cardiopulmonary parameters such as heart rate, oxygen consumption, metabolic rate, and cost of transport are reduced compared to 1 g, whereas stroke volume seems to increase with decreasing gravity levels. Biomechanical studies reveal that ground reaction forces, mechanical work, stance phase duration, stride frequency, duty factor and preferred walk-to-run transition speed are reduced compared to 1 g. Partial gravity exposure below 0.4 g seems to be insufficient to maintain musculoskeletal and

  1. Response of Gravity, Magnetic, and Geoelectrical Resistivity Methods on Ngeni Southern Blitar Mineralization Zone

    NASA Astrophysics Data System (ADS)

    Sunaryo

    2018-03-01

    The research with entitle response of gravity, magnetic, and geoelectrical resistivity methods on Ngeni Southern Blitar mineralization zone has been done. This study aims to find the response of several geophysical methods of gravity, magnetic, and geoelectrical resistivity in an integrated manner. Gravity data acquisition was acquired 224 data which covers the whole region of Blitar district by using Gravity Meter La Coste & Romberg Model “G”, and magnetic data acquisition were acquired 195 data which covers the southern Blitar district only by using Proton Precession Magnetometer G-856. Meanwhile geoelectrical resistivity data only done in Ngeni village which is the location of phyropilite mining with the composition content of Fe, Si, Ca, S, Cu, and Mn by using ABEM Terrameter SAS 300C. Gravity data processing was performed to obtain the Bouguer anomaly value, which included unit conversion, tidal correction, drift correction, correction of tie point, base station correction, free air correction, and Bouguer correction. Magnetic data processing has been done by some corrections i.e daily, drift, and IGRF(International Geomagnetic Refference Field) to obtain the total magnetic anomaly. From gravity data processing has been obtained the simple Bouguer anomaly value in range from -10mGal until 115mGal. From this data processing has been obtained the total magnetic anomaly value in range from -650nT until 800nT. Meanwhile from geoelectrical resistivity 3.03Ωm until 11249.91 Ωm. There is a correlation between gravity anomaly, magnetic anomaly, and geoelectrical resistivity anomaly that are associated with deep anomaly, middle anomaly, and shallow anomaly.

  2. Space Station Freedom altitude strategy

    NASA Technical Reports Server (NTRS)

    Mcdonald, Brian M.; Teplitz, Scott B.

    1990-01-01

    The Space Station Freedom (SSF) altitude strategy provides guidelines and assumptions to determine an altitude profile for Freedom. The process for determining an altitude profile incorporates several factors such as where the Space Shuttle will rendezvous with the SSF, when reboosts must occur, and what atmospheric conditions exist causing decay. The altitude strategy has an influence on all areas of SSF development and mission planning. The altitude strategy directly affects the micro-gravity environment for experiments, propulsion and control system sizing, and Space Shuttle delivery manifests. Indirectly the altitude strategy influences almost every system and operation within the Space Station Program. Evolution of the SSF altitude strategy has been a very dynamic process over the past few years. Each altitude strategy in turn has emphasized a different consideration. Examples include a constant Space Shuttle rendezvous altitude for mission planning simplicity, or constant micro-gravity levels with its inherent emphasis on payloads, or lifetime altitudes to provide a safety buffer to loss of control conditions. Currently a new altitude strategy is in development. This altitude strategy will emphasize Space Shuttle delivery optimization. Since propellant is counted against Space Shuttle payload-to-orbit capacity, lowering the rendezvous altitude will not always increase the net payload-to-orbit, since more propellant would be required for reboost. This altitude strategy will also consider altitude biases to account for Space Shuttle launch slips and an unexpected worsening of atmospheric conditions. Safety concerns will define a lower operational altitude limit, while radiation levels will define upper altitude constraints. The evolution of past and current SSF altitude strategies and the development of a new altitude strategy which focuses on operational issues as opposed to design are discussed.

  3. Modulation of internal estimates of gravity during and after prolonged roll-tilts.

    PubMed

    Tarnutzer, Alexander A; Bertolini, Giovanni; Bockisch, Christopher J; Straumann, Dominik; Marti, Sarah

    2013-01-01

    Perceived direction of gravity, as assessed by the subjective visual vertical (SVV), shows roll-angle dependent errors that drift over time and a bias upon return to upright. According to Bayesian observer theory, the estimated direction of gravity is derived from the posterior probability distribution by combining sensory input and prior knowledge about earth-vertical in a statistically optimal fashion. Here we aimed to further characterize the stability of SVV during and after prolonged roll-tilts. Specifically we asked whether the post-tilt bias is related to the drift pattern while roll-tilted. Twenty-nine healthy human subjects (23-56 yo) repetitively adjusted a luminous arrow to the SVV over periods of 5 min while upright, roll-tilted (± 45°, ± 90°), and immediately after returning to upright. Significant (p<0.05) drifts (median absolute drift-amplitude: 10°/5 min) were found in 71% (± 45°) and 78% (± 90°) of runs. At ± 90° roll-tilt significant increases in absolute adjustment errors were more likely (76%), whereas significant increases (56%) and decreases (44%) were about equally frequent at ± 45°. When returning to upright, an initial bias towards the previous roll-position followed by significant exponential decay (median time-constant: 71 sec) was noted in 47% of all runs (all subjects pooled). No significant correlations were found between the drift pattern during and immediately after prolonged roll-tilt. We conclude that the SVV is not stable during and after prolonged roll-tilt and that the direction and magnitude of drift are individually distinct and roll-angle-dependent. Likely sensory and central adaptation and random-walk processes contribute to drift while roll-tilted. Lack of correlation between the drift and the post-tilt bias suggests that it is not the inaccuracy of the SVV estimate while tilted that determines post-tilt bias, but rather the previous head-roll orientation relative to gravity. We therefore favor central

  4. Laser, GPS and absolute gravimetry vertical positioning time series comparison at the OCA observatory, France

    NASA Astrophysics Data System (ADS)

    Nicolas, J.; Nocquet, J.; van Camp, M.; Coulot, D.

    2003-12-01

    Time-dependent displacements of stations usually have magnitude close to the accuracy of each individual technique, and it still remains difficult to separate the true geophysical motion from possible artifacts inherent to each space geodetic technique. The Observatoire de la C“te d'Azur (OCA), located at Grasse, France benefits from the collocation of several geodetic instruments and techniques (3 laser ranging stations, and a permanent GPS) what allows us to do a direct comparison of the time series. Moreover, absolute gravimetry measurement campaigns have also been regularly performed since 1997, first by the "Ecole et Observatoire des Sciences de la Terre (EOST) of Strasbourg, France, and more recently by the Royal Observatory of Belgium. This study presents a comparison between the positioning time series of the vertical component derived from the SLR and GPS analysis with the gravimetric results from 1997 to 2003. The laser station coordinates are based on a LAGEOS -1 and -2 combined solution using reference 10-day arc orbits, the ITRF2000 reference frame, and the IERS96 conventions. Different GPS weekly global solutions provided from several IGS are combined and compared to the SLR results. The absolute gravimetry measurements are converted into vertical displacements with a classical gradient. The laser time series indicate a strong annual signal at the level of about 3-4 cm peak to peak amplitude on the vertical component. Absolute gravimetry data agrees with the SLR results. GPS positioning solutions also indicate a significant annual term, but with a magnitude of only 50% of the one shown by the SLR solution and by the gravimetry measurements. Similar annual terms are also observed on other SLR sites we processed, but usually with! lower and various amplitudes. These annual signals are also compared to vertical positioning variations corresponding to an atmospheric loading model. We present the level of agreement between the different techniques and we

  5. Cellular basis of gravity resistance in plants

    NASA Astrophysics Data System (ADS)

    Hoson, Takayuki; Matsumoto, Shouhei; Inui, Kenichi; Zhang, Yan; Soga, Kouichi; Wakabayashi, Kazuyuki; Hashimoto, Takashi

    affected by gravity. We also examined the effects of hypergravity on the osmotic properties of azuki bean epicotyls, and found that epicotyls were capable of maintaining osmoregulation even under hypergravity conditions at least for a short period. The increase in level of total osmotic solutes was suppressed by long-term hypergravity treatment, which was accounted by suppres-sion of translocation of organic solutes such as sugars and amino acids. These various cellular events may contribute to sustaining the cell wall changes or cooperate with the cell wall in gravity resistance. Space experiments on the International Space Station will confirm whether this view is applicable to plant resistance to 1 g gravity, as to the resistance to hypergravity.

  6. A Climatological Study of Short-Period Gravity Waves and Ripples at Davis Station, Antarctica (68°S, 78°E), During the (Austral Winter February-October) Period 1999-2013

    NASA Astrophysics Data System (ADS)

    Rourke, S.; Mulligan, F. J.; French, W. J. R.; Murphy, D. J.

    2017-11-01

    A scanning radiometer deployed at Davis Station, Antarctica (68°S, 78°E), has been recording infrared (1.10-1.65 μm) images of a small region (24 km × 24 km) of the zenith night sky once per minute each austral winter night since February 1999. These images have been processed to extract information on the passage of gravity waves (GWs) (horizontal wavelength, λh > 15 km) and ripples (λh ≤ 15 km) over the observing station. Phase speeds, periods, horizontal wavelengths, and predominant propagation directions have been deduced. Observed speeds were found to be highly correlated with horizontal wavelengths as has been reported in previous studies. Reverse ray tracing of the detected GWs only enabled us to identify four distinct groups. On average, only 15% of waves detected can be traced back to the troposphere, and a large proportion ( 45%) were not successfully reverse traced substantially below the airglow layer. Two smaller groups were found to reach a termination condition for reverse ray tracing at altitudes near 50 km and 75 km. Of those that reached the termination altitude in the troposphere (10 km), most of the end points fell within a radius of 300 km of the station, with a very pronounced concentration of wave initiation to the northwest of the observing point. The predominant direction of propagation was southward, and they were observed throughout the year. Recent reports suggest the interaction of planetary waves with the background wind field as a potential source for these waves.

  7. Quantitative Velocity Field Measurements in Reduced-Gravity Combustion Science and Fluid Physics Experiments

    NASA Technical Reports Server (NTRS)

    Greenberg, Paul S.; Wernet, Mark P.

    1999-01-01

    Systems have been developed and demonstrated for performing quantitative velocity measurements in reduced gravity combustion science and fluid physics investigations. The unique constraints and operational environments inherent to reduced-gravity experimental facilities pose special challenges to the development of hardware and software systems. Both point and planar velocimetric capabilities are described, with particular attention being given to the development of systems to support the International Space Station laboratory. Emphasis has been placed on optical methods, primarily arising from the sensitivity of the phenomena of interest to intrusive probes. Limitations on available power, volume, data storage, and attendant expertise have motivated the use of solid-state sources and detectors, as well as efficient analysis capabilities emphasizing interactive data display and parameter control.

  8. Evaluation of ames Multistix-SG for urine specific gravity versus refractometer specific gravity.

    PubMed

    Adams, L J

    1983-12-01

    A comparison of urine specific gravity by a commercially available multiple reagent strip (Multistix-SG; Ames Division, Miles Laboratory) versus refractometer specific gravity (TS Meter; American Optical Corporation) was performed on 214 routine urine specimens. Agreement to +/- 0.005 was found in 72% of the specimens (r = 0.80). Urine specific gravity by the Multistix-SG showed a significant positive bias at urine pHs less than or equal to 6.0 and a negative bias at urine pHs greater than 7.0 in comparison to refractometer specific gravity. At concentrated (specific gravity greater than or equal to 1.020) specific gravities, up to 25% of urine specimens were misclassified as not concentrated by Multistix-SG specific gravity in comparison to refractometer specific gravity. The additional cost of the specific gravity reagent to a multiple reagent test strip in addition to the poor performance relative to refractometer specific gravity leads to the conclusion that including this specific gravity methodology on a multiple reagent strip is neither cost effective nor clinically useful.

  9. Marine magnetic survey and onshore gravity and magnetic survey, San Pablo Bay, northern California

    USGS Publications Warehouse

    Ponce, David A.; Denton, Kevin M.; Watt, Janet T.

    2016-09-12

    IntroductionFrom November 2011 to August 2015, the U.S. Geological Survey (USGS) collected more than 1,000 line-kilometers (length of lines surveyed in kilometers) of marine magnetic data on San Pablo Bay, 98 onshore gravity stations, and over 27 line-kilometers of ground magnetic data in northern California. Combined magnetic and gravity investigations were undertaken to study subsurface geologic structures as an aid in understanding the geologic framework and earthquake hazard potential in the San Francisco Bay Area. Furthermore, marine magnetic data illuminate local subsurface geologic features in the shallow crust beneath San Pablo Bay where geologic exposure is absent.Magnetic and gravity methods, which reflect contrasting physical properties of the subsurface, are ideal for studying San Pablo Bay. Exposed rock units surrounding San Pablo Bay consist mainly of Jurassic Coast Range ophiolite, Great Valley sequence, Franciscan Complex rocks, Miocene sedimentary rocks, and unconsolidated alluvium (Graymer and others, 2006). The contrasting magnetic and density properties of these rocks enable us to map their subsurface extent.

  10. Gravity sensing using Very Long Baseline Atom Interferometry

    NASA Astrophysics Data System (ADS)

    Schlippert, D.; Wodey, E.; Meiners, C.; Tell, D.; Schubert, C.; Ertmer, W.; Rasel, E. M.

    2017-12-01

    Very Long Baseline Atom Interferometry (VLBAI) has applications in high-accuracy absolute gravimetry, gravity-gradiometry, and for tests of fundamental physics. Thanks to the quadratic scaling of the phase shift with increasing free evolution time, extending the baseline of atomic gravimeters from tens of centimeters to meters puts resolutions of 10-13g and beyond in reach.We present the design and progress of key elements of the VLBAI-test stand: a dual-species source of Rb and Yb, a high-performance two-layer magnetic shield, and an active vibration isolation system allowing for unprecedented stability of the mirror acting as an inertial reference. We envisage a vibration-limited short-term sensitivity to gravitational acceleration of 1x10-8 m/s-2Hz-1/2 and up to a factor of 25 improvement when including additional correlation with a broadband seismometer. Here, the supreme long-term stability of atomic gravity sensors opens the route towards competition with superconducting gravimeters. The operation of VLBAI as a differential dual-species gravimeter using ultracold mixtures of Yb and Rb atoms enables quantum tests of the universality of free fall (UFF) at an unprecedented level of <10-13, potentially surpassing the best experiments to date.

  11. Gravity sensing using Very Long Baseline Atom Interferometry

    NASA Astrophysics Data System (ADS)

    Schlippert, Dennis; Wodey, Étienne; Meiners, Christian; Tell, Dorothee; Schubert, Christian; Ertmer, Wolfgang; Rasel, Ernst M.

    2017-04-01

    Very Long Baseline Atom Interferometry (VLBAI) has applications in high-accuracy absolute gravimetry, gravity-gradiometry, and for tests of fundamental physics. Thanks to the quadratic scaling of the phase shift with increasing free evolution time, extending the baseline of atomic gravimeters from tens of centimeters to meters puts resolutions of 10-13 g and beyond in reach. We present the design and progress of key elements of the VLBAI-test stand: a dual-species source of Rb and Yb, a high-performance two-layer magnetic shield, and an active vibration isolation system allowing for unprecedented stability of the mirror acting as an inertial reference. We envisage a vibration-limited short-term sensitivity to gravitational acceleration of 1 .10-8 m/s2 / Hz1/2 and up to a factor of 25 improvement when including additional correlation with a broadband seismometer. Here, the supreme long-term stability of atomic gravity sensors opens the route towards competition with superconducting gravimeters. The operation of VLBAI as a differential dual-species gravimeter using ultracold mixtures of Yb and Rb atoms enables quantum tests of the universality of free fall (UFF) at an unprecedented level of <=10-13 , potentially surpassing the best experiments to date.

  12. Gravitational acceleration as a cue for absolute size and distance?

    NASA Technical Reports Server (NTRS)

    Hecht, H.; Kaiser, M. K.; Banks, M. S.

    1996-01-01

    When an object's motion is influenced by gravity, as in the rise and fall of a thrown ball, the vertical component of acceleration is roughly constant at 9.8 m/sec2. In principle, an observer could use this information to estimate the absolute size and distance of the object (Saxberg, 1987a; Watson, Banks, von Hofsten, & Royden, 1992). In five experiments, we examined people's ability to utilize the size and distance information provided by gravitational acceleration. Observers viewed computer simulations of an object rising and falling on a trajectory aligned with the gravitational vector. The simulated objects were balls of different diameters presented across a wide range of simulated distances. Observers were asked to identify the ball that was presented and to estimate its distance. The results showed that observers were much more sensitive to average velocity than to the gravitational acceleration pattern. Likewise, verticality of the motion and visibility of the trajectory's apex had negligible effects on the accuracy of size and distance judgments.

  13. Direct recovery of mean gravity anomalies from satellite to satellite tracking

    NASA Technical Reports Server (NTRS)

    Hajela, D. P.

    1974-01-01

    The direct recovery was investigated of mean gravity anomalies from summed range rate observations, the signal path being ground station to a geosynchronous relay satellite to a close satellite significantly perturbed by the short wave features of the earth's gravitational field. To ensure realistic observations, these were simulated with the nominal orbital elements for the relay satellite corresponding to ATS-6, and for two different close satellites (one at about 250 km height, and the other at about 900 km height) corresponding to the nominal values for GEOS-C. The earth's gravitational field was represented by a reference set of potential coefficients up to degree and order 12, considered as known values, and by residual gravity anomalies obtained by subtracting the anomalies, implied by the potential coefficients, from their terrestrial estimates. It was found that gravity anomalies could be recovered from strong signal without using any a-priori terrestrial information, i.e. considering their initial values as zero and also assigning them a zero weight matrix. While recovering them from weak signal, it was necessary to use the a-priori estimate of the standard deviation of the anomalies to form their a-priori diagonal weight matrix.

  14. Recent gravity monitoring of ETS transient deformation in the northern Cascadia Subduction Zone

    NASA Astrophysics Data System (ADS)

    Henton, J. A.; Dragert, H.; Lambert, A.; Nykolaishen, L.; Liard, J.; Courtier, N.

    2012-12-01

    High-precision gravity observations are sensitive to vertical motion of the observation site as well as mass redistribution and can be used to investigate the physical processes involved in Episodic Tremor and Slip (ETS). For the 2011 ETS event in the northern portion of the Cascadia Subduction Zone, absolute gravity (AG) observations and continuous gravity monitoring with an earth tide (ET) gravimeter were carried out at the Pacific Geoscience Centre (PGC) in order to augment the GPS and borehole strainmeter (BSM) data used in constraining models of slip on the subduction plate interface. Unfortunately, the surface displacements and strains for the August 2011 slow slip event were significantly less for southern Vancouver Island than those recorded for previous events making this particular ETS episode less than ideal for the search for attendant gravity signals. Nonetheless, preliminary AG results for the 2011 ETS event show a subtle (≤ 1μGal) negative transient gravity signal but its origin is not clear. This residual gravity change, after accounting for the gravity offset predicted from the observed height change, may reflect a migration of fluids and/or a change in mean density. No significant vertical change is observed in the GPS data. Based on previous events, this is expected since PGC lies close to the hinge-line for vertical deformation for regional ETS. We attempt to improve the resolution of the GPS results by including results from NRCan's PPP software in our analyses. Data from the 3 co-located BSM's operated by the Plate Boundary Observatory show discrepancies that indicate interfering signals of likely non-tectonic origin. Preliminary data from the ET gravimeter appear to be dominated by non-linear instrumental drift that is often observed at the outset of continuous operation at a new location. To improve the resolution of the gravity signal, future monitoring of ETS events will be supplemented at PGC by continuous gravity measurements with a

  15. EDITORIAL: Focus section on quantum gravity - 25 years of quantum gravity Focus section on quantum gravity - 25 years of quantum gravity

    NASA Astrophysics Data System (ADS)

    Samuel, Joseph

    2011-08-01

    The problem of quantum gravity has been with us for over 80 years. After quantum theory was established in the 1920s, it was successfully applied to the electromagnetic field. Over the years there have been many attempts to bring gravity into the fold. There has been work on the Hamiltonian formulation of general relativity, perturbative approaches to quantum gravity and more. Much intellectual effort went into understanding conceptual and technical problems stemming from the general covariance of the theory. However, in earlier decades, the subject of quantum gravity was relatively on the fringes of theoretical physics research, pursued by a small and diverse community of people. In the mid 1980s the situation changed dramatically. The subject of quantum gravity came to the forefront of fundamental physics research, no longer a backwater but the mainstream. Quantum gravity was widely acknowledged as the last frontier of fundamental physics and attracted the brightest young people. Unlike in previous decades, workers in this area were no longer isolated groups or individuals ploughing lonely furrows, but organised into coherent `programmes' for a concerted attack on the problem. The main programmes coincidentally were all formulated in the mid 1980s. The two `programmes' covered in this section are string theory and loop quantum gravity. String theory was born an offshoot of Hadronic models in particle physics and reflects the particle physicists view that gravity is just one more interaction to be encompassed by a unified theory. Loop quantum gravity reflects the general relativist's conviction that gravity is different and should not be treated as a perturbation about Minkowski spacetime. Each of these approaches has its proponents, adherents and critics. It is now about a quarter of a century since these programmes started. It is perhaps a good time to take stock and assess where we are now and where each of these programmes is headed. The idea in this focus

  16. Spherically symmetric conformal gravity and ''gravitational bubbles''

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Berezin, V.A.; Dokuchaev, V.I.; Eroshenko, Yu.N., E-mail: berezin@inr.ac.ru, E-mail: dokuchaev@inr.ac.ru, E-mail: eroshenko@inr.ac.ru

    2016-01-01

    The general structure of the spherically symmetric solutions in the Weyl conformal gravity is described. The corresponding Bach equations are derived for the special type of metrics, which can be considered as the representative of the general class. The complete set of the pure vacuum solutions is found. It consists of two classes. The first one contains the solutions with constant two-dimensional curvature scalar of our specific metrics, and the representatives are the famous Robertson-Walker metrics. One of them we called the ''gravitational bubbles'', which is compact and with zero Weyl tensor. Thus, we obtained the pure vacuum curved space-timesmore » (without any material sources, including the cosmological constant) what is absolutely impossible in General Relativity. Such a phenomenon makes it easier to create the universe from ''nothing''. The second class consists of the solutions with varying curvature scalar. We found its representative as the one-parameter family. It appears that it can be conformally covered by the thee-parameter Mannheim-Kazanas solution. We also investigated the general structure of the energy-momentum tensor in the spherical conformal gravity and constructed the vectorial equation that reveals clearly some features of non-vacuum solutions. Two of them are explicitly written, namely, the metrics à la Vaidya, and the electrovacuum space-time metrics.« less

  17. The dynamics of a space station tethered refueling facility

    NASA Technical Reports Server (NTRS)

    Abbott, P.; Rudolph, L. K.; Fester, D. A.

    1986-01-01

    The fluid stored in a tethered orbital refueling facility is settled at the bottom of the storage tanks by gravity-gradient forces. The fluid motions (slosh) induced by outside disturbances must be limited to ensure the tank outlet is not uncovered during a fluid transfer. The dynamics of a LO2/LH2 TORF attached to the space station have been analyzed to identify design parameters necessary to limit fluid motion. Using the worst case disturbance of a shuttle docking at the space station, the fluid motion was found to be a function of tether length and allowable facility swing angle. Acceptable fluid behavior occurs for tether lengths of at least 1000 ft. To ensure motions induced by separate disturbances do not add to unacceptable values, a slosh damping coefficient of 5 percent is recommended.

  18. An advanced technology space station for the year 2025, study and concepts

    NASA Technical Reports Server (NTRS)

    Queijo, M. J.; Butterfield, A. J.; Cuddihy, W. F.; King, C. B.; Garn, P. A.

    1987-01-01

    A survey was made of potential space station missions that might exist in the 2020 to 2030 time period. Also, a brief study of the current state-of-the-art of the major subsystems was undertaken, and trends in technologies that could impact the subsystems were reviewed. The results of the survey and study were then used to arrive at a conceptual design of a space station for the year 2025. Factors addressed in the conceptual design included requirements for artificial gravity, synergies between subsystems, and the use of robotics. Suggestions are made relative to more in-depth studies concerning the conceptual design and alternative configurations.

  19. Absolute acceleration measurements on STS-50 from the Orbital Acceleration Research Experiment (OARE)

    NASA Technical Reports Server (NTRS)

    Blanchard, Robert C.; Nicholson, John Y.; Ritter, James R.

    1994-01-01

    Orbital Acceleration Research Experiment (OARE) data on Space Transportation System (STS)-50 have been examined in detail during a 2-day time period. Absolute acceleration levels have been derived at the OARE location, the orbiter center-of-gravity, and at the STS-50 spacelab Crystal Growth Facility. During the interval, the tri-axial OARE raw telemetered acceleration measurements have been filtered using a sliding trimmed mean filter in order to remove large acceleration spikes (e.g., thrusters) and reduce the noise. Twelve OARE measured biases in each acceleration channel during the 2-day interval have been analyzed and applied to the filtered data. Similarly, the in situ measured x-axis scale factors in the sensor's most sensitive range were also analyzed and applied to the data. Due to equipment problem(s) on this flight, both y- and z-axis sensitive range scale factors were determined in a separate process using orbiter maneuvers and subsequently applied to the data. All known significant low-frequency corrections at the OARE location (i.e., both vertical and horizontal gravity-gradient, and rotational effects) were removed from the filtered data in order to produce the acceleration components at the orbiter center-of-gravity, which are the aerodynamic signals along each body axis. Results indicate that there is a force being applied to the Orbiter in addition to the aerodynamic forces. The OARE instrument and all known gravitational and electromagnetic forces have been reexamined, but none produces the observed effect. Thus, it is tentatively concluded that the orbiter is creating the environment observed. At least part of this force is thought to be due to the Flash Evaporator System.

  20. Animal research on the Space Station

    NASA Technical Reports Server (NTRS)

    Bonting, S. L.; Arno, R. D.; Corbin, S. D.

    1987-01-01

    The need for in-depth, long- and short-term animal experimentation in space to qualify man for long-duration space missions, and to study the effects of the absence and presence of Earth's gravity and of heavy particle radiation on the development and functioning of vertebrates is described. The major facilities required for these investigations and to be installed on the Space Station are: modular habitats for holding rodents and small primates in full bioisolation; a habitat holding facility; 1.8 and 4.0 m dia centrifuges; a multipurpose workbench; and a cage cleaner/disposal system. The design concepts, functions, and characteristics of these facilities are described.

  1. Magma Intrusion at Mount St. Helens, Washington, from Temporal Gravity Variations

    NASA Astrophysics Data System (ADS)

    Battaglia, Maurizio; Lisowski, Mike; Dzursin, Dan; Poland, Mike; Schilling, Steve; Diefenbach, Angie; Wynn, Jeff

    2017-04-01

    Mount St. Helens is a stratovolcano in the Pacific Northwest region of the United States, best known for its explosive eruption in May 1980 - deadliest and most economically destructive volcanic event in US history. Volcanic activity renewed in September 2004 with a dome forming eruption that lasted until 2008. This eruption was surprising because the preceding four years had seen the fewest earthquakes and no significant deformation since the 1980-86 eruption ended. After the dome forming eruption ended in July 2008, the volcano seismic activity and deformation went back to background values. Time-dependent gravimetric measurements can detect subsurface processes long before magma flow leads to earthquakes or other eruption precursors. A high-precision gravity monitoring network (referenced to a base station 36 km NW of the volcano) was set up at Mount St Helens in 2010. Measurements were made at 12 sites on the volcano (at altitudes between 1200 and 2350 m a.s.l.) and 4 sites far afield during the summers of 2010, 2012, and 2014. The repeated gravity measurements revealed an increase in gravity between 2010 and 2014. Positive residual gravity anomalies remained after accounting for changes in surface height, in the Crater Glacier, and in the shallow hydrothermal aquifer. The pattern of residual gravity changes, with a maximum of 57±12 μGal from 2010 to 2014, is radially symmetric and centered on the 2004-08 lava dome. Inversion of the residual gravity signal points to a source 2.5-4 km beneath the crater floor (i.e., in the magma conduit that fed eruptions in 1980-86 and 2004-08). We attribute the gravity increase to re-inflation of the magma plumbing system following the 2004-8 eruption. Recent seismic activity (e.g., the seismic swarm of March 2016) has been interpreted as a response to the slow recharging of the volcano magma chamber.

  2. Gravity changes during animal development affect IgM heavy-chain transcription and probably lymphopoiesis.

    PubMed

    Huin-Schohn, Cécile; Guéguinou, Nathan; Schenten, Véronique; Bascove, Matthieu; Koch, Guillemette Gauquelin; Baatout, Sarah; Tschirhart, Eric; Frippiat, Jean-Pol

    2013-01-01

    Our previous research demonstrated that spaceflight conditions affect antibody production in response to an antigenic stimulation in adult amphibians. Here, we investigated whether antibody synthesis is affected when animal development occurs onboard a space station. To answer this question, embryos of the Iberian ribbed newt, Pleurodeles waltl, were sent to the International Space Station (ISS) before the initiation of immunoglobulin heavy-chain expression. Thus, antibody synthesis began in space. On landing, we determined the effects of spaceflight on P. waltl development and IgM heavy-chain transcription. Results were compared with those obtained using embryos that developed on Earth. We find that IgM heavy-chain transcription is doubled at landing and that spaceflight does not affect P. waltl development and does not induce inflammation. We also recreated the environmental modifications encountered by the embryos during their development onboard the ISS. This strategy allowed us to demonstrate that gravity change is the factor responsible for antibody heavy-chain transcription modifications that are associated with NF-κB mRNA level variations. Taken together, and given that the larvae were not immunized, these data suggest a modification of lymphopoiesis when gravity changes occur during ontogeny.

  3. Imaging subsurface density structure in Luynnier volcanic field, Saudi Arabia, using 3D gravity inversion technique

    NASA Astrophysics Data System (ADS)

    Aboud, Essam; El-shrief, Adel; Alqahtani, Faisal; Mogren, Saad

    2017-04-01

    On 19 May, 2009, an earthquake of magnitude (M=5.4) shocked the most volcanically active recent basaltic fields, Luynnier volcanic field, northwestern Saudi Arabia. This event was the largest recorded one since long time ago. Government evacuated the surrounding residents around the epicenter for over 3 months away from any future volcanic activity. The seismic event caused damages to buildings in the village around the epicenter and resulted in surface fissure trending in NNW-SSE direction with about 8 km length. Seismologists from Saudi Geological Survey (SGS) worked out on locating the epicenter and the cause of this earthquake. They collected seismic data from Saudi Geological Surveys Station Network as well as installed broadband seismic stations around the region of the earthquake. They finally concluded that the main cause of the M=5.4 event is dike intrusion at depth of about 5 km (not reached to the surface). In the present work, we carried out detailed ground/airborne gravity survey around the surficial fissure to image the subsurface volcanic structure where about 380 gravity stations were recorded covering the main fissure in an area of 600 km2. Gravity data was analyzed using CET edge detection tools and 3D inversion technique. The results revealed that, there is a magma chamber/body beneath the surface at 5-20 km depth and the main reason for the M=5.4 earthquake is tectonic settings of the Red Sea. Additionally, the area is characterized by set of faults trending in NW direction, parallel to the Red Sea, and most of the volcanic cones were located on faults/contacts implying that, they are structurally controlled. The 8-km surficial crack is extended SE underneath the surface.

  4. Passive and Active Stabilization of Liquid Bridges in Low Gravity

    NASA Technical Reports Server (NTRS)

    Marston, Philip L.; Thiessen, David B.; Marr-Lyon, Mark J.; Wei, Wei; Niederhaus, Charles E.; Truong, Duc K.

    2001-01-01

    Tests are planned in the low gravity environment of the International Space Station (ISS) of new methods for the suppression of the capillary instability of liquid bridges. Our suppression methods are unusual in that they are not limited to liquid bridges having very special properties and may impact a variety of low-gravity and earth-based technologies. There are two main approaches to be investigated: (1) Passive Acoustic Stabilization (PAS); and (2) Active Electrostatic Stabilization (AES). In PAS, the suppression of the mode growth is accomplished by placing the bridge in an acoustic field having the appropriate properties such that the acoustic radiation pressure automatically pulls outward on the thinnest portion of the bridge. In AES, the bridge deformation is sensed optically and counteracted by actively adjusting the electrostatic Maxwell stresses via two ring electrodes concentric with the slightly conducting bridge to offset the growth of the unstable mode. While the present work emphasizes cylindrical bridges, the methods need not be restricted to that case. The methods to be explored are relevant to the suppression of capillary instabilities in floating zone crystal growth, breakup of liquid jets and columns, bubbles, and annular films as well as the management of coolants or propellants in low-gravity.

  5. A comparison of the gravity field over Central Europe from superconducting gravimeters, GRACE and global hydrological models, using EOF analysis

    NASA Astrophysics Data System (ADS)

    Crossley, David; de Linage, Caroline; Hinderer, Jacques; Boy, Jean-Paul; Famiglietti, James

    2012-05-01

    We analyse data from seven superconducting gravimeter (SG) stations in Europe from 2002 to 2007 from the Global Geodynamics Project (GGP) and compare seasonal variations with data from GRACE and several global hydrological models - GLDAS, WGHM and ERA-Interim. Our technique is empirical orthogonal function (EOF) decomposition of the fields that allows for the inherent incompatibility of length scales between ground and satellite observations. GGP stations below the ground surface pose a problem because part of the attraction from soil moisture comes from above the gravimeter, and this gives rise to a complex (mixed) gravity response. The first principle component (PC) of the EOF decomposition is the main indicator for comparing the fields, although for some of the series it accounts for only about 50 per cent of the variance reduction. PCs for GRACE solutions RL04 from CSR and GFZ are filtered with a cosine taper (degrees 20-40) and a Gaussian window (350 km). Significant differences are evident between GRACE solutions from different groups and filters, though they all agree reasonably well with the global hydrological models for the predominantly seasonal signal. We estimate the first PC at 10-d sampling to be accurate to 1 μGal for GGP data, 1.5 μGal for GRACE data and 1 μGal between the three global hydrological models. Within these limits the CNES/GRGS solution and ground GGP data agree at the 79 per cent level, and better when the GGP solution is restricted to the three above-ground stations. The major limitation on the GGP side comes from the water mass distribution surrounding the underground instruments that leads to a complex gravity effect. To solve this we propose a method for correcting the SG residual gravity series for the effects of soil moisture above the station.

  6. Experiment plans to study preignition processes of a pool fire in low gravity. M.S. Thesis - 1988 Final Report

    NASA Technical Reports Server (NTRS)

    Schiller, David N.

    1989-01-01

    Science requirements are specified to guide experimental studies of transient heat transfer and fluid flow in an enclosure containing a two-layer gas-and-liquid system heated unevenly from above. Specifications are provided for experiments in three separate settings: (1) a normal gravity laboratory, (2) the NASA-LeRC Drop towers, and (3) a space-based laboratory (e.g., Shuttle, Space Station). A rationale is developed for both minimum and desired requirement levels. The principal objective of the experimental effort is to validate a computational model of the enclosed liquid fuel pool during the preignition phase and to determine via measurement the role of gravity on the behavior of the system. Preliminary results of single-phase normal gravity experiments and simulations are also presented.

  7. Space Station - The base for tomorrow's electronic industry

    NASA Technical Reports Server (NTRS)

    Naumann, Robert J.

    1985-01-01

    The potential value of space material processing on the Space Station for the electronics industry is examined. The primary advantages of the space environment for producing high-purity semiconductors and electrooptical materials are identified as the virtual absence of gravity (suppressing buoyancy-driven convection in melts and density segregation of alloys) and the availabilty of high vacuum (with high pumping speed and heat rejection). The recent history of material development and processing technology in the electronics industry is reviewed, and the principal features of early space experiments are outlined.

  8. Correlation of Normal Gravity Mixed Convection Blowoff Limits with Microgravity Forced Flow Blowoff Limits

    NASA Technical Reports Server (NTRS)

    Marcum, Jeremy W.; Olson, Sandra L.; Ferkul, Paul V.

    2016-01-01

    The axisymmetric rod geometry in upward axial stagnation flow provides a simple way to measure normal gravity blowoff limits to compare with microgravity Burning and Suppression of Solids - II (BASS-II) results recently obtained aboard the International Space Station. This testing utilized the same BASS-II concurrent rod geometry, but with the addition of normal gravity buoyant flow. Cast polymethylmethacrylate (PMMA) rods of diameters ranging from 0.635 cm to 3.81 cm were burned at oxygen concentrations ranging from 14 to 18% by volume. The forced flow velocity where blowoff occurred was determined for each rod size and oxygen concentration. These blowoff limits compare favorably with the BASS-II results when the buoyant stretch is included and the flow is corrected by considering the blockage factor of the fuel. From these results, the normal gravity blowoff boundary for this axisymmetric rod geometry is determined to be linear, with oxygen concentration directly proportional to flow speed. We describe a new normal gravity 'upward flame spread test' method which extrapolates the linear blowoff boundary to the zero stretch limit in order to resolve microgravity flammability limits-something current methods cannot do. This new test method can improve spacecraft fire safety for future exploration missions by providing a tractable way to obtain good estimates of material flammability in low gravity.

  9. Stratospheric gravity waves at southern hemisphere orographic hotspots: 2003-2014 AIRS/Aqua observations

    NASA Astrophysics Data System (ADS)

    Hoffmann, Lars; Grimsdell, Alison W.; Alexander, M. Joan

    2017-04-01

    Stratospheric gravity waves from small-scale orographic sources are currently not well-represented in general circulation models. This may be a reason why many simulations have difficulty reproducing the dynamical behaviour of the southern hemisphere polar vortex in a realistic manner. Here we discuss a 12-year record (2003 - 2014) of stratospheric gravity wave activity at southern hemisphere orographic hotspots as observed by the Atmospheric InfraRed Sounder (AIRS) aboard the National Aeronautics and Space Administration's (NASA's) Aqua satellite. We introduce a simple and effective approach, referred to as the 'two-box method', to detect gravity wave activity from infrared nadir sounder measurements and to discriminate between gravity waves from orographic and other sources. From austral mid fall to mid spring (April - October) the contributions of orographic sources to the observed gravity wave occurrence frequencies were found to be largest for the Andes (90%), followed by the Antarctic Peninsula (76%), Kerguelen Islands (73%), Tasmania (70%), New Zealand (67%), Heard Island (60%), and other hotspots (24 - 54%). Mountain wave activity was found to be closely correlated with peak terrain altitudes, and with zonal winds in the lower troposphere and mid stratosphere. We propose a simple model to predict the occurrence of mountain wave events in the AIRS observations using zonal wind thresholds at 3 hPa and 750 hPa. The model has significant predictive skill for hotspots where gravity wave activity is primarily due to orographic sources. It typically reproduces seasonal variations of the mountain wave occurrence frequencies at the Antarctic Peninsula and Kerguelen Islands from near zero to over 60% with mean absolute errors of 4 - 5 percentage points. The prediction model can be used to disentangle upper level wind effects on observed occurrence frequencies from low level source and other influences. The data and methods presented here can help to identify

  10. Absolute And Convective Instability and Splitting of a Liquid Jet at Microgravity

    NASA Technical Reports Server (NTRS)

    Lin, S. P.

    2001-01-01

    The objective is to establish a definitive role of the capillary, viscous, and inertial forces at a liquid-gas interface in the absence of gravity by using the fluid dynamics problem of the stability of a liquid jet as a vehicle. The objective is achieved by reexamining known theories and new theories that can be verified completely only in microgravity. The experiments performed in the microgravity facility at NASA Glenn Research Center enable the verification of the theory with experimental data. Of particular interest are (1) to capture for the first time the image of absolute instability, (2) to elucidate the fundamental difference in the physical mechanism of the drop and spray formation from a liquid jet, and (3) to find the origin of the newly discovered phenomenon of jet splitting on earth and in space.

  11. Opportunities to Intercalibrate Radiometric Sensors From International Space Station

    NASA Technical Reports Server (NTRS)

    Roithmayr, C. M.; Lukashin, C.; Speth, P. W.; Thome, K. J.; Young, D. F.; Wielicki, B. A.

    2012-01-01

    Highly accurate measurements of Earth's thermal infrared and reflected solar radiation are required for detecting and predicting long-term climate change. We consider the concept of using the International Space Station to test instruments and techniques that would eventually be used on a dedicated mission such as the Climate Absolute Radiance and Refractivity Observatory. In particular, a quantitative investigation is performed to determine whether it is possible to use measurements obtained with a highly accurate reflected solar radiation spectrometer to calibrate similar, less accurate instruments in other low Earth orbits. Estimates of numbers of samples useful for intercalibration are made with the aid of year-long simulations of orbital motion. We conclude that the International Space Station orbit is ideally suited for the purpose of intercalibration.

  12. Estimating the absolute wealth of households.

    PubMed

    Hruschka, Daniel J; Gerkey, Drew; Hadley, Craig

    2015-07-01

    To estimate the absolute wealth of households using data from demographic and health surveys. We developed a new metric, the absolute wealth estimate, based on the rank of each surveyed household according to its material assets and the assumed shape of the distribution of wealth among surveyed households. Using data from 156 demographic and health surveys in 66 countries, we calculated absolute wealth estimates for households. We validated the method by comparing the proportion of households defined as poor using our estimates with published World Bank poverty headcounts. We also compared the accuracy of absolute versus relative wealth estimates for the prediction of anthropometric measures. The median absolute wealth estimates of 1,403,186 households were 2056 international dollars per capita (interquartile range: 723-6103). The proportion of poor households based on absolute wealth estimates were strongly correlated with World Bank estimates of populations living on less than 2.00 United States dollars per capita per day (R(2)  = 0.84). Absolute wealth estimates were better predictors of anthropometric measures than relative wealth indexes. Absolute wealth estimates provide new opportunities for comparative research to assess the effects of economic resources on health and human capital, as well as the long-term health consequences of economic change and inequality.

  13. On the stability conditions for theories of modified gravity in the presence of matter fields

    NASA Astrophysics Data System (ADS)

    De Felice, Antonio; Frusciante, Noemi; Papadomanolakis, Georgios

    2017-03-01

    We present a thorough stability analysis of modified gravity theories in the presence of matter fields. We use the Effective Field Theory framework for Dark Energy and Modified Gravity to retain a general approach for the gravity sector and a Sorkin-Schutz action for the matter one. Then, we work out the proper viability conditions to guarantee in the scalar sector the absence of ghosts, gradient and tachyonic instabilities. The absence of ghosts can be achieved by demanding a positive kinetic matrix, while the lack of a gradient instability is ensured by imposing a positive speed of propagation for all the scalar modes. In case of tachyonic instability, the mass eigenvalues have been studied and we work out the appropriate expressions. For the latter, an instability occurs only when the negative mass eigenvalue is much larger, in absolute value, than the Hubble parameter. We discuss the results for the minimally coupled quintessence model showing for a particular set of parameters two typical behaviours which in turn lead to a stable and an unstable configuration. Moreover, we find that the speeds of propagation of the scalar modes strongly depend on matter densities, for the beyond Horndeski theories. Our findings can be directly employed when testing modified gravity theories as they allow to identify the correct viability space.

  14. On the stability conditions for theories of modified gravity in the presence of matter fields

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    De Felice, Antonio; Frusciante, Noemi; Papadomanolakis, Georgios, E-mail: antonio.defelice@yukawa.kyoto-u.ac.jp, E-mail: fruscian@iap.fr, E-mail: papadomanolakis@lorentz.leidenuniv.nl

    We present a thorough stability analysis of modified gravity theories in the presence of matter fields. We use the Effective Field Theory framework for Dark Energy and Modified Gravity to retain a general approach for the gravity sector and a Sorkin-Schutz action for the matter one. Then, we work out the proper viability conditions to guarantee in the scalar sector the absence of ghosts, gradient and tachyonic instabilities. The absence of ghosts can be achieved by demanding a positive kinetic matrix, while the lack of a gradient instability is ensured by imposing a positive speed of propagation for all themore » scalar modes. In case of tachyonic instability, the mass eigenvalues have been studied and we work out the appropriate expressions. For the latter, an instability occurs only when the negative mass eigenvalue is much larger, in absolute value, than the Hubble parameter. We discuss the results for the minimally coupled quintessence model showing for a particular set of parameters two typical behaviours which in turn lead to a stable and an unstable configuration. Moreover, we find that the speeds of propagation of the scalar modes strongly depend on matter densities, for the beyond Horndeski theories. Our findings can be directly employed when testing modified gravity theories as they allow to identify the correct viability space.« less

  15. Absolute GPS Positioning Using Genetic Algorithms

    NASA Astrophysics Data System (ADS)

    Ramillien, G.

    A new inverse approach for restoring the absolute coordinates of a ground -based station from three or four observed GPS pseudo-ranges is proposed. This stochastic method is based on simulations of natural evolution named genetic algorithms (GA). These iterative procedures provide fairly good and robust estimates of the absolute positions in the Earth's geocentric reference system. For comparison/validation, GA results are compared to the ones obtained using the classical linearized least-square scheme for the determination of the XYZ location proposed by Bancroft (1985) which is strongly limited by the number of available observations (i.e. here, the number of input pseudo-ranges must be four). The r.m.s. accuracy of the non -linear cost function reached by this latter method is typically ~10-4 m2 corresponding to ~300-500-m accuracies for each geocentric coordinate. However, GA can provide more acceptable solutions (r.m.s. errors < 10-5 m2), even when only three instantaneous pseudo-ranges are used, such as a lost of lock during a GPS survey. Tuned GA parameters used in different simulations are N=1000 starting individuals, as well as Pc=60-70% and Pm=30-40% for the crossover probability and mutation rate, respectively. Statistical tests on the ability of GA to recover acceptable coordinates in presence of important levels of noise are made simulating nearly 3000 random samples of erroneous pseudo-ranges. Here, two main sources of measurement errors are considered in the inversion: (1) typical satellite-clock errors and/or 300-metre variance atmospheric delays, and (2) Geometrical Dilution of Precision (GDOP) due to the particular GPS satellite configuration at the time of acquisition. Extracting valuable information and even from low-quality starting range observations, GA offer an interesting alternative for high -precision GPS positioning.

  16. Human Biomechanical and Cardiopulmonary Responses to Partial Gravity – A Systematic Review

    PubMed Central

    Richter, Charlotte; Braunstein, Bjoern; Winnard, Andrew; Nasser, Mona; Weber, Tobias

    2017-01-01

    The European Space Agency has recently announced to progress from low Earth orbit missions on the International Space Station to other mission scenarios such as exploration of the Moon or Mars. Therefore, the Moon is considered to be the next likely target for European human space explorations. Compared to microgravity (μg), only very little is known about the physiological effects of exposure to partial gravity (μg < partial gravity <1 g). However, previous research studies and experiences made during the Apollo missions comprise a valuable source of information that should be taken into account when planning human space explorations to reduced gravity environments. This systematic review summarizes the different effects of partial gravity (0.1–0.4 g) on the human musculoskeletal, cardiovascular and respiratory systems using data collected during the Apollo missions as well as outcomes from terrestrial models of reduced gravity with either 1 g or microgravity as a control. The evidence-based findings seek to facilitate decision making concerning the best medical and exercise support to maintain astronauts' health during future missions in partial gravity. The initial search generated 1,323 publication hits. Out of these 1,323 publications, 43 studies were included into the present analysis and relevant data were extracted. None of the 43 included studies investigated long-term effects. Studies investigating the immediate effects of partial gravity exposure reveal that cardiopulmonary parameters such as heart rate, oxygen consumption, metabolic rate, and cost of transport are reduced compared to 1 g, whereas stroke volume seems to increase with decreasing gravity levels. Biomechanical studies reveal that ground reaction forces, mechanical work, stance phase duration, stride frequency, duty factor and preferred walk-to-run transition speed are reduced compared to 1 g. Partial gravity exposure below 0.4 g seems to be insufficient to maintain musculoskeletal and

  17. Benefits from synergies and advanced technologies for an advanced-technology space station

    NASA Technical Reports Server (NTRS)

    Garrett, L. Bernard; Ferebee, Melvin J., Jr.; Queijo, Manuel J.; Butterfield, Ansel J.

    1991-01-01

    A configuration for a second-generation advanced technology space station has been defined in a series of NASA-sponsored studies. Definitions of subsystems specifically addressed opportunities for beneficial synergistic interactions and those potential synergies and their benefits are identified. One of the more significant synergistic benefits involves the multi-function utilization of water within a large system that generates artificial gravity by rotation. In such a system, water not only provides the necessary crew life support, but also serves as counterrotator mass, as moveable ballast, and as a source for propellant gases. Additionally, the synergistic effects between advanced technology materials, operation at reduced artificial gravity, and lower cabin atmospheric pressure levels show beneficial interactions that can be quantified in terms of reduced mass to orbit.

  18. Development of the Two Phase Flow Separator Experiment for a Reduced Gravity Aircraft Flight

    NASA Technical Reports Server (NTRS)

    Golliher, Eric; Gotti, Daniel; Owens, Jay; Gilkey, Kelly; Pham, Nang; Stehno, Philip

    2016-01-01

    The recent hardware development and testing of a reduced gravity aircraft flight experiment has provided valuable insights for the future design of the Two Phase Flow Separator Experiment (TPFSE). The TPFSE is scheduled to fly within the Fluids Integration Rack (FIR) aboard the International Space Station (ISS) in 2020. The TPFSE studies the operational limits of gas and liquid separation of passive cyclonic separators. A passive cyclonic separator utilizes only the inertia of the incoming flow to accomplish the liquid-gas separation. Efficient phase separation is critical for environmental control and life support systems, such as recovery of clean water from bioreactors, for long duration human spaceflight missions. The final low gravity aircraft flight took place in December 2015 aboard NASA's C9 airplane.

  19. Rapid rotators revisited: absolute dimensions of KOI-13

    NASA Astrophysics Data System (ADS)

    Howarth, Ian D.; Morello, Giuseppe

    2017-09-01

    We analyse Kepler light-curves of the exoplanet Kepler Object of Interest no. 13b (KOI-13b) transiting its moderately rapidly rotating (gravity-darkened) parent star. A physical model, with minimal ad hoc free parameters, reproduces the time-averaged light-curve at the ˜10 parts per million level. We demonstrate that this Roche-model solution allows the absolute dimensions of the system to be determined from the star's projected equatorial rotation speed, ve sin I*, without any additional assumptions; we find a planetary radius RP = (1.33 ± 0.05) R♃, stellar polar radius Rp★ = (1.55 ± 0.06) R⊙, combined mass M* + MP( ≃ M*) = (1.47 ± 0.17) M⊙ and distance d ≃ (370 ± 25) pc, where the errors are dominated by uncertainties in relative flux contribution of the visual-binary companion KOI-13B. The implied stellar rotation period is within ˜5 per cent of the non-orbital, 25.43-hr signal found in the Kepler photometry. We show that the model accurately reproduces independent tomographic observations, and yields an offset between orbital and stellar-rotation angular-momentum vectors of 60.25° ± 0.05°.

  20. Need for artificial gravity on a manned Mars mission?

    NASA Technical Reports Server (NTRS)

    Sharp, Joseph C.

    1986-01-01

    Drawing upon the extensive Soviet and Skylab medical observations, the need for artificial gravity (g) on a manned Mars mission is discussed. Little hard data derived from well done experiments exist. This dearth of information is primarily due to two factors. Inability to collect tissues from astronauts for ethical or operational reasons. Second, there was not opportunities to fly animals in space to systematically evaluate the extent of the problem, and to develop and then to prove the effectiveness of countermeasures. The Skylab and space station will provide the opportunity to study these questions and validate suggested solutions.

  1. Water exploration using Magnetotelluric and gravity data analysis; Wadi Nisah, Riyadh, Saudi Arabia

    NASA Astrophysics Data System (ADS)

    Aboud, Essam; Saud, Ramzi; Asch, Theodore; Aldamegh, Khaled; Mogren, Saad

    2014-12-01

    Saudi Arabia is a desert country with no permanent rivers or lakes and very little rainfall. Ground water aquifers are the major source of water in Saudi Arabia. In the Riyadh region, several Wadies including Wadi Nisah store about 14 × 106 m3 of water, which is extracted for local irrigation purposes. In such areas, the water wells are as shallow as 200-300 m in depth. The importance of Wadi Nisah is because the subsurface water aquifers that are present there could support the region for many years as a water resource. Accordingly, in this study, we performed a Magnetotelluric survey using a portable broadband sounding system (MT24/LF) to evaluate the ground water aquifer at great depths. We collected 10 broadband Magnetotelluric sounding stations (1 station/day) with an interval of about 2-3 km reaching a profile length of about 25-30 km along Wadi Nisah. Additionally, we used available gravity data to image the subsurface structure containing the aquifer. MT results indicated a low resistivity layer, associated with alluvium deposits, which was defined at a depth of about 1-2 km and extended horizontally about 15 km. Gravity data analysis was used to model this resistivity layer indicating a basement surface at 3-4 km depth.

  2. International Space Station (ISS)

    NASA Image and Video Library

    2001-02-01

    In the grasp of the Shuttle's Remote Manipulator System (RMS) robot arm, the U.S. Laboratory, Destiny, is moved from its stowage position in the cargo bay of the Space Shuttle Atlantis. This photograph was taken by astronaut Thomas D. Jones during his Extravehicular Activity (EVA). The American-made Destiny module is the cornerstone for space-based research aboard the orbiting platform and the centerpiece of the International Space Station (ISS), where unprecedented science experiments will be performed in the near-zero gravity of space. Destiny will also serve as the command and control center for the ISS. The aluminum module is 8.5- meters (28-feet) long and 4.3-meters (14-feet) in diameter. The laboratory consists of three cylindrical sections and two endcones with hatches that will be mated to other station components. A 50.9-centimeter (20-inch-) diameter window is located on one side of the center module segment. This pressurized module is designed to accommodate pressurized payloads. It has a capacity of 24 rack locations. Payload racks will occupy 15 locations especially designed to support experiments. The Destiny module was built by the Boeing Company under the direction of the Marshall Space Flight Center.

  3. International Space Station (ISS)

    NASA Image and Video Library

    2001-02-01

    In the grasp of the Shuttle's Remote Manipulator System (RMS) robot arm, the U.S. Laboratory, Destiny, is moved from its stowage position in the cargo bay of the Space Shuttle Atlantis. This photograph was taken by astronaut Thomas D. Jones during his Extravehicular Activity (EVA). The American-made Destiny module is the cornerstone for space-based research aboard the orbiting platform and the centerpiece of the International Space Station (ISS), where unprecedented science experiments will be performed in the near-zero gravity of space. Destiny will also serve as the command and control center for the ISS. The aluminum module is 8.5- meters (28-feet) long and 4.3-meters (14-feet) in diameter. The laboratory consists of three cylindrical sections and two endcones with hatches that will be mated to other station components. A 50.9-centimeter- (20-inch-) diameter window is located on one side of the center module segment. This pressurized module is designed to accommodate pressurized payloads. It has a capacity of 24 rack locations. Payload racks will occupy 15 locations especially designed to support experiments. The Destiny module was built by the Boeing Company under the direction of the Marshall Space Flight Center.

  4. International Space Station (ISS)

    NASA Image and Video Library

    2001-03-01

    In this Space Shuttle STS-102 mission image, the Payload Equipment Restraint System H-Strap is shown at the left side of the U.S. Laboratory hatch and behind Astronaut James D. Weatherbee, mission specialist. PERS is an integrated modular system of components designed to assist the crew of the International Space Station (ISS) in restraining and carrying necessary payload equipment and tools in a microgravity environment. The Operations Development Group, Flight Projects Directorate at the Marshall Space Flight Center (MSFC), while providing operation support to the ISS Materials Science Research Facility (MSRF), recognized the need for an on-orbit restraint system to facilitate control of lose objects, payloads, and tools. The PERS is the offspring of that need and it helps the ISS crew manage tools and rack components that would otherwise float away in the near-zero gravity environment aboard the Space Station. The system combines Kevlar straps, mesh pockets, Velcro and a variety of cornecting devices into a portable, adjustable system. The system includes the Single Strap, the H-Strap, the Belly Pack, the Laptop Restraint Belt, and the Tool Page Case. The Single Strap and the H-Strap were flown on this mission. The PERS concept was developed by industrial design students at Auburn University and the MSFC Flight Projects Directorate.

  5. 3D joint inversion of gravity-gradient and borehole gravity data

    NASA Astrophysics Data System (ADS)

    Geng, Meixia; Yang, Qingjie; Huang, Danian

    2017-12-01

    Borehole gravity is increasingly used in mineral exploration due to the advent of slim-hole gravimeters. Given the full-tensor gradiometry data available nowadays, joint inversion of surface and borehole data is a logical next step. Here, we base our inversions on cokriging, which is a geostatistical method of estimation where the error variance is minimised by applying cross-correlation between several variables. In this study, the density estimates are derived using gravity-gradient data, borehole gravity and known densities along the borehole as a secondary variable and the density as the primary variable. Cokriging is non-iterative and therefore is computationally efficient. In addition, cokriging inversion provides estimates of the error variance for each model, which allows direct assessment of the inverse model. Examples are shown involving data from a single borehole, from multiple boreholes, and combinations of borehole gravity and gravity-gradient data. The results clearly show that the depth resolution of gravity-gradient inversion can be improved significantly by including borehole data in addition to gravity-gradient data. However, the resolution of borehole data falls off rapidly as the distance between the borehole and the feature of interest increases. In the case where the borehole is far away from the target of interest, the inverted result can be improved by incorporating gravity-gradient data, especially all five independent components for inversion.

  6. Gravity and Magnetotelluric Modeling of the Santo Domingo Basin, Northern New Mexico

    NASA Astrophysics Data System (ADS)

    Zamudio, K. D.; Keithline, N.; Blum, C.; Cunningham, E.; Fromont, A.; Jorgensen, M.; Lee, R.; McBride, K.; Saez Berrios, P.; Harper, C.; Pellerin, L.; McPhee, D.; Ferguson, J. F.

    2015-12-01

    The Santo Domingo Basin, one of a series of basins within the Rio Grande Rift, is located between Santa Fe and Albuquerque, NM, and has been the focus of research by the Summer of Geophysical Experience (SAGE) program since 2000. Gravity, magnetotelluric (MT), and seismic data have been collected throughout the region, although we are concentrating on gravity and MT data collected during SAGE 2014 and 2015. The study area is located in the center of the Santo Domingo basin, an extensional, Miocene age, rift basin, in an area that was minimally involved in the preceding local Laramide orogenic activity. Rift sediments (~3.5 km thick) are underlain by Eocene age sediments that were shed from adjacent uplifts. Up to 3 km of Mesozoic and Paleozoic sediments are preserved above the Precambrian basement. Geologic outcrop, borehole and seismic reflection data, and known density values were used in the construction of a ~100 km-long, generalized geologic cross section from which a gravity response was calculated. The modeled gravity response makes fairly definitive predictions about the geometry of the basin as well as the stratigraphy and faulting within and bounding the basin. MT data was collected at ten stations within the basin. The MT sounding curves exhibit one-dimensional behavior at short periods (<10 s), not surprisingly considering the relatively flat local structure in the area. Layered-earth MT models, without geologic constraints, show a conductive (<10 ohm-m) layer at ~1.5 km above a more resistive layer (>1000 ohm-m) at ~ 3.5-4 km. Conductivities of the major stratigraphic units have been determined from well logs and previous MT modeling. Forward and inverse MT models constrained by the gravity-modeled geologic cross section are used to develop a conductivity model consistent with the geology, and are a step towards a better unified treatment of MT, seismic and gravity data.

  7. Low-gravity Orbiting Research Laboratory Environment Potential Impact on Space Biology Research

    NASA Technical Reports Server (NTRS)

    Jules, Kenol

    2006-01-01

    One of the major objectives of any orbital space research platform is to provide a quiescent low gravity, preferably a zero gravity environment, to perform fundamental as well as applied research. However, small disturbances exist onboard any low earth orbital research platform. The impact of these disturbances must be taken into account by space research scientists during their research planning, design and data analysis in order to avoid confounding factors in their science results. The reduced gravity environment of an orbiting research platform in low earth orbit is a complex phenomenon. Many factors, among others, such as experiment operations, equipment operation, life support systems and crew activity (if it is a crewed platform), aerodynamic drag, gravity gradient, rotational effects as well as the vehicle structural resonance frequencies (structural modes) contribute to form the overall reduced gravity environment in which space research is performed. The contribution of these small disturbances or accelerations is precisely why the environment is NOT a zero gravity environment, but a reduced acceleration environment. This paper does not discuss other factors such as radiation, electromagnetic interference, thermal and pressure gradient changes, acoustic and CO2 build-up to name a few that affect the space research environment as well, but it focuses solely on the magnitude of the acceleration level found on orbiting research laboratory used by research scientists to conduct space research. For ease of analysis this paper divides the frequency spectrum relevant to most of the space research disciplines into three regimes: a) quasi-steady, b) vibratory and c) transient. The International Space Station is used as an example to illustrate the point. The paper discusses the impact of these three regimes on space biology research and results from space flown experiments are used to illustrate the potential negative impact of these disturbances (accelerations

  8. Estimating the absolute wealth of households

    PubMed Central

    Gerkey, Drew; Hadley, Craig

    2015-01-01

    Abstract Objective To estimate the absolute wealth of households using data from demographic and health surveys. Methods We developed a new metric, the absolute wealth estimate, based on the rank of each surveyed household according to its material assets and the assumed shape of the distribution of wealth among surveyed households. Using data from 156 demographic and health surveys in 66 countries, we calculated absolute wealth estimates for households. We validated the method by comparing the proportion of households defined as poor using our estimates with published World Bank poverty headcounts. We also compared the accuracy of absolute versus relative wealth estimates for the prediction of anthropometric measures. Findings The median absolute wealth estimates of 1 403 186 households were 2056 international dollars per capita (interquartile range: 723–6103). The proportion of poor households based on absolute wealth estimates were strongly correlated with World Bank estimates of populations living on less than 2.00 United States dollars per capita per day (R2 = 0.84). Absolute wealth estimates were better predictors of anthropometric measures than relative wealth indexes. Conclusion Absolute wealth estimates provide new opportunities for comparative research to assess the effects of economic resources on health and human capital, as well as the long-term health consequences of economic change and inequality. PMID:26170506

  9. (abstract) Venus Gravity Field

    NASA Technical Reports Server (NTRS)

    Konopliv, A. S.; Sjogren, W. L.

    1995-01-01

    A global gravity field model of Venus to degree and order 75 (5772 spherical harmonic coefficients) has been estimated from Doppler radio tracking of the orbiting spacecraft Pioneer Venus Orbiter (1979-1992) and Magellan (1990-1994). After the successful aerobraking of Magellan, a near circular polar orbit was attained and relatively uniform gravity field resolution (approximately 200 km) was obtained with formal uncertainties of a few milligals. Detailed gravity for several highland features are displayed as gravity contours overlaying colored topography. The positive correlation of typography with gravity is very high being unlike that of the Earth, Moon, and Mars. The amplitudes are Earth-like, but have significantly different gravity-topography ratios for different features. Global gravity, geoid, and isostatic anomaly maps as well as the admittance function are displayed.

  10. Genetic Analysis of Mice Skin Exposed by Hyper-Gravity

    NASA Astrophysics Data System (ADS)

    Takahashi, Rika; Terada, Masahiro; Seki, Masaya; Higashibata, Akira; Majima, Hideyuki J.; Ohira, Yoshinobu; Mukai, Chiaki; Ishioka, Noriaki

    2013-02-01

    In the space environment, physiological alterations, such as low bone density, muscle weakness and decreased immunity, are caused by microgravity and cosmic radiation. On the other hand, it is known that the leg muscles are hypertrophy by 2G-gravity. An understanding of the effects on human body from microgravity to hyper-gravity is very important. Recently, the Japan Aerospace Exploration Agency (JAXA) has started a project to detect the changes on gene expression and mineral metabolism caused by microgravity by analyzing the hair of astronauts who stay in the international Space Station (ISS) for a long time. From these results of human hair’s research, the genetic effects of human hair roots by microgravity will become clear. However, it is unclear how the gene expression of hair roots was effected by hypergravity. Therefore, in this experiment, we analyzed the effect on mice skin contained hair roots by comparing microgravity or hypergravity exposed mice. The purpose of this experiment is to evaluate the genetic effects on mice skin by microgravity or 2G-gravity. The samples were taken from mice exposed to space flight (FL) or hypergravity environment (2G) for 3-months, respectively. The extracted and amplified RNA from these mice skin was used to DNA microarray analysis. in this experiment, we analyzed the effect of gravity by using mice skin contained hair roots, which exposed space (FL) and hyper-gravity (2G) for 3 months and each control. By DNA microarray analysis, we found the common 98 genes changed in both FL and 2G. Among these 98 genes, the functions and pathways were identified by Gene Ontology (GO) analysis and Ingenuity Pathways Analysis (IPA) software. Next, we focused the one of the identified pathways and compared the effects on each molecules in this pathways by the different environments, such as FL and 2G. As the results, we could detect some interesting molecules, which might be depended on the gravity levels. In addition, to investigate

  11. Gravity brake

    DOEpatents

    Lujan, Richard E.

    2001-01-01

    A mechanical gravity brake that prevents hoisted loads within a shaft from free-falling when a loss of hoisting force occurs. A loss of hoist lifting force may occur in a number of situations, for example if a hoist cable were to break, the brakes were to fail on a winch, or the hoist mechanism itself were to fail. Under normal hoisting conditions, the gravity brake of the invention is subject to an upward lifting force from the hoist and a downward pulling force from a suspended load. If the lifting force should suddenly cease, the loss of differential forces on the gravity brake in free-fall is translated to extend a set of brakes against the walls of the shaft to stop the free fall descent of the gravity brake and attached load.

  12. Mean gravity anomalies from a combination of Apollo/ATS 6 and GEOS 3/ATS 6 SST tracking campaigns. [Satellite to Satellite Tracking

    NASA Technical Reports Server (NTRS)

    Kahn, W. D.; Klosko, S. M.; Wells, W. T.

    1982-01-01

    Advances in satellite tracking data accuracy and coverage over the past 15 years have led to major improvements in global geopotential models. But the spacial resolution of the gravity field obtained solely from satellite dynamics sensed by tracking data is still of the order of 1000 km. Attention is given to an approach which will provide information regarding the fine structure of the gravity field on the basis of an application of local corrections to the global field. According to this approach, a basic satellite to satellite tracked (SST) range-rate measurement is constructed from the link between a ground station, a geosynchronous satellite (ATS 6), and a near-earth satellite (Apollo or GEOS 3). Attention is given to a mathematical model, the simulation of SST gravity anomaly estimation accuracies, a gravity anomaly estimation from GEOS 3/ATS 6 and Apollo/ATS 6 SST observations, and an evaluation of the mean gravity anomalies determined from SST.

  13. Effect of science laboratory centrifuge of space station environment

    NASA Technical Reports Server (NTRS)

    Searby, Nancy

    1990-01-01

    It is argued that it is essential to have a centrifuge operating during manned space station operations. Background information and a rationale for the research centrifuge are given. It is argued that we must provide a controlled acceleration environment for comparison with microgravity studies. The lack of control groups in previous studies throws into question whether the obseved effects were the result of microgravity or not. The centrifuge could be used to provide a 1-g environment to supply specimens free of launch effects for long-term studies. With the centrifuge, the specimens could be immediately transferred to microgravity without undergoing gradual acclimation. Also, the effects of artificial gravity on humans could be investigated. It is also argued that the presence of the centrifuge on the space station will not cause undo vibrations or other disturbing effects.

  14. Life sciences research on the space station: An introduction

    NASA Technical Reports Server (NTRS)

    1985-01-01

    The Space Station will provide an orbiting, low gravity, permanently manned facility for scientific research, starting in the 1990s. The facilities for life sciences research are being designed to allow scientific investigators to perform research in Space Medicine and Space Biology, to study the consequences of long-term exposure to space conditions, and to allow for the permanent presence of humans in space. This research, using humans, animals, and plants, will provide an understanding of the effects of the space environment on the basic processes of life. In addition, facilities are being planned for remote observations to study biologically important elements and compounds in space and on other planets (exobiology), and Earth observations to study global ecology. The life sciences community is encouraged to plan for participation in scientific research that will be made possible by the Space Station research facility.

  15. Cutoff for extensions of massive gravity and bi-gravity

    NASA Astrophysics Data System (ADS)

    Matas, Andrew

    2016-04-01

    Recently there has been interest in extending ghost-free massive gravity, bi-gravity, and multi-gravity by including non-standard kinetic terms and matter couplings. We first review recent proposals for this class of extensions, emphasizing how modifications of the kinetic and potential structure of the graviton and modifications of the coupling to matter are related. We then generalize existing no-go arguments in the metric language to the vielbein language in second-order form. We give an ADM argument to show that the most promising extensions to the kinetic term and matter coupling contain a Boulware-Deser ghost. However, as recently emphasized, we may still be able to view these extensions as effective field theories below some cutoff scale. To address this possibility, we show that there is a decoupling limit where a ghost appears for a wide class of matter couplings and kinetic terms. In particular, we show that there is a decoupling limit where the linear effective vielbein matter coupling contains a ghost. Using the insight we gain from this decoupling limit analysis, we place an upper bound on the cutoff for the linear effective vielbein coupling. This result can be generalized to new kinetic interactions in the vielbein language in second-order form. Combined with recent results, this provides a strong uniqueness argument on the form of ghost-free massive gravity, bi-gravity, and multi-gravity.

  16. Global Gravity Field Determination by Combination of terrestrial and Satellite Gravity Data

    NASA Astrophysics Data System (ADS)

    Fecher, T.; Pail, R.; Gruber, T.

    2011-12-01

    A multitude of impressive results document the success of the satellite gravity field mission GOCE with a wide field of applications in geodesy, geophysics and oceanography. The high performance of GOCE gravity field models can be further improved by combination with GRACE data, which is contributing the long wavelength signal content of the gravity field with very high accuracy. An example for such a consistent combination of satellite gravity data are the satellite-only models GOCO01S and GOCO02S. However, only the further combination with terrestrial and altimetric gravity data enables to expand gravity field models up to very high spherical harmonic degrees and thus to achieve a spatial resolution down to 20-30 km. First numerical studies for high-resolution global gravity field models combining GOCE, GRACE and terrestrial/altimetric data on basis of the DTU10 model have already been presented. Computations up to degree/order 600 based on full normal equations systems to preserve the full variance-covariance information, which results mainly from different weights of individual terrestrial/altimetric data sets, have been successfully performed. We could show that such large normal equations systems (degree/order 600 corresponds to a memory demand of almost 1TByte), representing an immense computational challenge as computation time and memory requirements put high demand on computational resources, can be handled. The DTU10 model includes gravity anomalies computed from the global model EGM08 in continental areas. Therefore, the main focus of this presentation lies on the computation of high-resolution combined gravity field models based on real terrestrial gravity anomaly data sets. This is a challenge due to the inconsistency of these data sets, including also systematic error components, but a further step to a real independent gravity field model. This contribution will present our recent developments and progress by using independent data sets at certain

  17. Workstations and gloveboxes for space station

    NASA Technical Reports Server (NTRS)

    Junge, Maria

    1990-01-01

    Lockheed Missiles and Space Company is responsible for designing, developing, and building the Life Sciences Glovebox, the Laboratory Sciences Workbench, and the Maintenance Workstation plus 16 other pieces of equipment for the U.S. Laboratory Module of the Space Station Freedom. The Laboratory Sciences Workbench and the Maintenance Workstation were functionally combined into a double structure to save weight and volume which are important commodities on the Space Station Freedom. The total volume of these items is approximately 180 cubic feet. These workstations and the glovebox will be delivered to NASA in 1994 and will be launched in 1995. The very long lifetime of 30 years presents numerous technical challenges in the areas of design and reliability. The equipment must be easy to use by international crew members and also easy to maintain on-orbit. For example, seals must be capable of on-orbit changeout and reverification. The stringent contamination requirements established for Space Station Freedom equipment also complicate the zero gravity glovebox design. The current contamination control system for the Life Sciences Glovebox and the Maintenance Workstation is presented. The requirement for the Life Sciences Glovebox to safely contain toxic, reactive, and radioactive materials presents challenges. Trade studies, CAD simulation techniques and design challenges are discussed to illustrate the current baseline conceptual designs. Areas which need input from the user community are identified.

  18. 20 CFR 404.1205 - Absolute coverage groups.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 20 Employees' Benefits 2 2011-04-01 2011-04-01 false Absolute coverage groups. 404.1205 Section... Covered § 404.1205 Absolute coverage groups. (a) General. An absolute coverage group is a permanent... are not under a retirement system. An absolute coverage group may include positions which were...

  19. Precise Gravity Measurements for Lunar Laser Ranging at Apache Point Observatory

    NASA Astrophysics Data System (ADS)

    Crossley, D. J.; Murphy, T.; Boy, J.; De Linage, C.; Wheeler, R. D.; Krauterbluth, K.

    2012-12-01

    Lunar Laser Ranging (LLR) at Apache Point Observatory began in 2006 under the APOLLO project using a 3.5 m telescope on a 2780 m summit in New Mexico. Recent improvements in the technical operations are producing uncertainties at the few-mm level in the 1.5 x 10^13 cm separation of the solar orbits of the Earth and Moon. This level of sensitivity permits a number of important aspects of gravitational theory to be tested. Among these is the Equivalence Principle that determines the universality of free fall, tests of the time variation of the Gravitational Constant G, deviations from the inverse square law, and preferred frame effects. In 2009 APOLLO installed a superconducting gravimeter (SG) on the concrete pier under the main telescope to further constrain the deformation of the site as part of an initiative to improve all aspects of the modeling process. We have analyzed more than 3 years of high quality SG data that provides unmatched accuracy in determining the local tidal gravimetric factors for the solid Earth and ocean tide loading. With on-site gravity we have direct measurements of signals such as polar motion, and can compute global atmospheric and hydrological loading for the site using GLDAS and local hydrology models that are compared with the SG observations. We also compare the SG residuals with satellite estimates of seasonal ground gravity variations from the GRACE mission. Apache Point is visited regularly by a team from the National Geospatial-Intelligence Agency to provide absolute gravity values for the calibration of the SG and to determine secular gravity changes. Nearby GPS location P027 provides continuous position information from the Plate Boundary Observatory of Earthscope that is used to correlate gravity/height variations at the site. Unusual aspects of the data processing include corrections for the telescope azimuth that appear as small offsets at the 1 μGal level and can be removed by correlating the azimuth data with the SG

  20. Generalized quasitopological gravity

    NASA Astrophysics Data System (ADS)

    Hennigar, Robie A.; KubizÅák, David; Mann, Robert B.

    2017-05-01

    We construct the most general, to cubic order in curvature, theory of gravity whose (most general) static spherically symmetric vacuum solutions are fully described by a single field equation. The theory possesses the following remarkable properties: (i) It has a well-defined Einstein gravity limit, (ii) it admits "Schwarzschild-like" solutions characterized by a single metric function, (iii) on maximally symmetric backgrounds it propagates the same degrees of freedom as Einstein's gravity, and (iv) Lovelock and quasitopological gravities, as well as the recently developed Einsteinian cubic gravity [Bueno and Cano Phys. Rev. D 94, 104005 (2016)., 10.1103/PhysRevD.94.104005] in four dimensions, are recovered as special cases. We perform a brief analysis of asymptotically flat black holes in this theory and study their thermodynamics.

  1. Gravity waves produced by the total solar eclipse of 1 August 2008

    NASA Astrophysics Data System (ADS)

    Marty, Julien; Francis, Dalaudier; Damien, Ponceau; Elisabeth, Blanc; Ulziibat, Munkhuu

    2010-05-01

    Gravity waves are a major component of atmospheric small scale dynamics because of their ability to transport energy and momentum over considerable distances and of their interactions with the mean circulation or other waves. They produce pressure variations which can be detected at the ground by microbarographs. The solar intensity reduction which occurs in the atmosphere during solar eclipses is known to act as a temporary source of large scale gravity waves. Despite decades of research, observational evidence for a characteristic bow-wave response of the atmosphere to eclipse passages remains elusive. A new versatile numerical model (Marty, J. and Dalaudier, F.: Linear spectral numerical model for internal gravity wave propagation. J. Atmos. Sci. (in press)) is presented and applied to the cooling of the atmosphere during a solar eclipse. Calculated solutions appear to be in good agreement with ground pressure fluctuations recorded during the total solar eclipse of 1 August 2008. To the knowledge of the authors, this is the first time that such a result is presented. A three-dimensional linear spectral numerical model is used to propagate internal gravity wave fluctuations in a stably stratified atmosphere. The model is developed to get first-order estimations of gravity wave fluctuations produced by identified sources. It is based on the solutions of the linearized fundamental fluid equations and uses the fully-compressible dispersion relation for inertia-gravity waves. The spectral implementation excludes situations involving spatial variations of buoyancy frequency or background wind. However density stratification variations are taken into account in the calculation of fluctuation amplitudes. In addition to gravity wave packet free propagation, the model handles both impulsive and continuous sources. It can account for spatial and temporal variations of the sources allowing to cover a broad range of physical situations. It is applied to the case of solar

  2. Gravity, Magnetism, and "Down": Non-Physics College Students' Conceptions of Gravity

    ERIC Educational Resources Information Center

    Asghar, Anila; Libarkin, Julie C.

    2010-01-01

    This study investigates how students enrolled in entry-level geology, most of whom would graduate from college without university-level physics courses, thought about and applied the concept of gravity while solving problems concerning gravity. The repercussions of students' gravity concepts are then considered in the context of non-physics…

  3. Control - Demands mushroom as station grows

    NASA Technical Reports Server (NTRS)

    Szirmay, S. Z.; Blair, J.

    1983-01-01

    The NASA space station, which is presently in the planning stage, is to be composed of both rigid and nonrigid modules, rotating elements, and flexible appendages subjected to environmental disturbances from the earth's atmospheric gravity gradient, and magnetic field, as well as solar radiation and self-generated disturbances. Control functions, which will originally include attitude control, docking and berthing control, and system monitoring and management, will with evolving mission objectives come to encompass such control functions as articulation control, autonomous navigation, space traffic control, and large space structure control. Attention is given to the advancements in modular, distributed, and adaptive control methods, as well as system identification and hardware fault tolerance techniques, which will be required.

  4. The Gravity Probe B Flight Dewar

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Gravity Probe B (GP-B) is the relativity experiment developed at Stanford University to test two extraordinary predictions of Albert Einstein's general theory of relativity. This photograph is of the Gravity Probe B flight dewar, a metal container made like a vacuum bottle that is used especially for storing liquefied gases, that will maintain the experiment at a temperature just above absolute zero, staying cold for two years. The experiment will measure, very precisely, the expected tiny changes in the direction of the spin axes of four gyroscopes contained in an Earth-orbiting satellite at 400-mile altitude. So free are the gyroscopes from disturbance that they will provide an almost perfect space-time reference system. They will measure how space and time are very slightly warped by the presence of the Earth, and, more profoundly, how the Earth's rotation very slightly drags space-time around with it. These effects, though small for the Earth, have far-reaching implications for the nature of matter and the structure of the Universe. GP-B is among the most thoroughly researched programs ever undertaken by NASA. This is the story of a scientific quest in which physicists and engineers have collaborated closely over many years. Inspired by their quest, they have invented a whole range of technologies -- technologies that are already enlivening other branches of science and engineering. Launched in 2004 and managed for NASA by the Marshall Space Flight Center, development of the GP-B is the responsibility of Stanford University, with major subcontractor Lockheed Martin Corporation. (Photo Credit: Lockheed Martin Corporation/R. Underwood)

  5. Toward global mapping of river discharge using satellite images and at-many-stations hydraulic geometry

    PubMed Central

    Gleason, Colin J.; Smith, Laurence C.

    2014-01-01

    Rivers provide critical water supply for many human societies and ecosystems, yet global knowledge of their flow rates is poor. We show that useful estimates of absolute river discharge (in cubic meters per second) may be derived solely from satellite images, with no ground-based or a priori information whatsoever. The approach works owing to discovery of a characteristic scaling law uniquely fundamental to natural rivers, here termed a river’s at-many-stations hydraulic geometry. A first demonstration using Landsat Thematic Mapper images over three rivers in the United States, Canada, and China yields absolute discharges agreeing to within 20–30% of traditional in situ gauging station measurements and good tracking of flow changes over time. Within such accuracies, the door appears open for quantifying river resources globally with repeat imaging, both retroactively and henceforth into the future, with strong implications for water resource management, food security, ecosystem studies, flood forecasting, and geopolitics. PMID:24639551

  6. Toward global mapping of river discharge using satellite images and at-many-stations hydraulic geometry.

    PubMed

    Gleason, Colin J; Smith, Laurence C

    2014-04-01

    Rivers provide critical water supply for many human societies and ecosystems, yet global knowledge of their flow rates is poor. We show that useful estimates of absolute river discharge (in cubic meters per second) may be derived solely from satellite images, with no ground-based or a priori information whatsoever. The approach works owing to discovery of a characteristic scaling law uniquely fundamental to natural rivers, here termed a river's at-many-stations hydraulic geometry. A first demonstration using Landsat Thematic Mapper images over three rivers in the United States, Canada, and China yields absolute discharges agreeing to within 20-30% of traditional in situ gauging station measurements and good tracking of flow changes over time. Within such accuracies, the door appears open for quantifying river resources globally with repeat imaging, both retroactively and henceforth into the future, with strong implications for water resource management, food security, ecosystem studies, flood forecasting, and geopolitics.

  7. Gravity model improvement using GEOS 3 /GEM 9 and 10/. [and Seasat altimetry data

    NASA Technical Reports Server (NTRS)

    Lerch, F. J.; Wagner, C. A.; Klosko, S. M.; Laubscher, R. E.

    1979-01-01

    Although errors in previous gravity models have produced large uncertainties in the orbital position of GEOS 3, significant improvement has been obtained with new geopotential solutions, Goddard Earth Model (GEM) 9 and 10. The GEM 9 and 10 solutions for the potential coefficients and station coordinates are presented along with a discussion of the new techniques employed. Also presented and discussed are solutions for three fundamental geodetic reference parameters, viz. the mean radius of the earth, the gravitational constant, and mean equatorial gravity. Evaluation of the gravity field is examined together with evaluation of GEM 9 and 10 for orbit determination accuracy. The major objectives of GEM 9 and 10 are achieved. GEOS 3 orbital accuracies from these models are about 1 m in their radial components for 5-day arc lengths. Both models yield significantly improved results over GEM solutions when compared to surface gravimetry, Skylab and GEOS 3 altimetry, and highly accurate BE-C (Beacon Explorer-C) laser ranges. The new values of the parameters discussed are given.

  8. Geodesy and gravity experiment in earth orbit using a superconducting gravity gradiometer

    NASA Technical Reports Server (NTRS)

    Paik, H. J.

    1985-01-01

    A superconducting gravity gradiometer is under development with NASA support for space application. It is planned that a sensitive three-axis gravity gradiometer will be flown in a low-altitude (about 160 km) polar orbit in the 1990's for the purpose of obtaining a high-resolution gravity map of the earth. The large twice-an-orbit term in the harmonic expansion of gravity coming from the oblateness of the earth can be analyzed to obtain a precision test of the inverse square law at a distance of 100-1000 km. In this paper, the design, operating principle, and performance of the superconducting gravity gradiometer are described. The concept of a gravity-gradiometer mission (GGM), which is in an initial stage of development is discussed. In particular, requirements that such a mission imposes on the design of the cryogenic spacecraft will be addressed.

  9. Artificial gravity - The evolution of variable gravity research

    NASA Technical Reports Server (NTRS)

    Fuller, Charles A.; Sulzman, Frank M.; Keefe, J. Richard

    1987-01-01

    The development of a space life science research program based on the use of rotational facilities is described. In-flight and ground centrifuges can be used as artificial gravity environments to study the following: nongravitational biological factors; the effects of 0, 1, and hyper G on man; counter measures for deconditioning astronauts in weightlessness; and the development of suitable artificial gravity for long-term residence in space. The use of inertial fields as a substitute for gravity, and the relations between the radius of the centrifuge and rotation rate and specimen height and rotation radius are examined. An example of a centrifuge study involving squirrel monkeys is presented.

  10. Similarity indices of meteo-climatic gauging stations: definition and comparison.

    PubMed

    Barca, Emanuele; Bruno, Delia Evelina; Passarella, Giuseppe

    2016-07-01

    Space-time dependencies among monitoring network stations have been investigated to detect and quantify similarity relationships among gauging stations. In this work, besides the well-known rank correlation index, two new similarity indices have been defined and applied to compute the similarity matrix related to the Apulian meteo-climatic monitoring network. The similarity matrices can be applied to address reliably the issue of missing data in space-time series. In order to establish the effectiveness of the similarity indices, a simulation test was then designed and performed with the aim of estimating missing monthly rainfall rates in a suitably selected gauging station. The results of the simulation allowed us to evaluate the effectiveness of the proposed similarity indices. Finally, the multiple imputation by chained equations method was used as a benchmark to have an absolute yardstick for comparing the outcomes of the test. In conclusion, the new proposed multiplicative similarity index resulted at least as reliable as the selected benchmark.

  11. Gravity

    NASA Astrophysics Data System (ADS)

    Poisson, Eric; Will, Clifford M.

    2014-05-01

    Preface; 1. Foundations of Newtonian gravity; 2. Structure of self-gravitating bodies; 3. Newtonian orbital dynamics; 4. Minkowski spacetime; 5. Curved spacetime; 6. Post-Minkowskian theory: formulation; 7. Post-Minkowskian theory: implementation; 8. Post-Newtonian theory: fundamentals; 9. Post-Newtonian theory: system of isolated bodies; 10. Post-Newtonian celestial mechanics, astrometry and navigation; 11. Gravitational waves; 12. Radiative losses and radiation reaction; 13. Alternative theories of gravity; References; Index.

  12. The research of a solution on locating optimally a station for seismic disasters rescue in a city

    NASA Astrophysics Data System (ADS)

    Yao, Qing-Lin

    1995-02-01

    When the stations for seismic disasters rescue in future or the similars are designed on a network of communication line, the general absolute center of a graph needs to be solved to reduce the requirements in the number of stations and running parameters and to establish an optimal station in a sense distribution of the rescue arrival time by the way of locating optimally the stations. The existing solution on this problem was proposed by Edward (1978) in which, however, there is serious deviation. In this article, the work of Edward (1978) is developed in both formula and figure, more correct solution is proposed and proved. Then the result from the newer solution is contrasted with that from the older one in a instance about locating optimally the station for seismic disasters rescue.

  13. Combustion of Metals in Reduced-Gravity and Extra Terrestrial Environments

    NASA Technical Reports Server (NTRS)

    Branch, M.C.; Abbud-Madrid, A.; Daily, J. W.

    1999-01-01

    combustion. Second, a low-gravity environment is absolutely essential to remove the destructive effect of gravity on the shape of a molten metal droplet in order to study a spherically symmetric condition with large bulk samples. The larger size of the spherical metal droplet and the longer burning times available in reduced gravity extend the spatial and temporal dimensions to permit careful probing of the flame structure and dynamics. Third, the influence of the radiative heat transfer from the solid oxides can be studied more carefully by generating a stagnant spherical shell of condensed products undisturbed by buoyancy.

  14. Magnetic and gravity studies of Mono Lake, east-central, California

    USGS Publications Warehouse

    Athens, Noah D.; Ponce, David A.; Jayko, Angela S.; Miller, Matt; McEvoy, Bobby; Marcaida, Mae; Mangan, Margaret T.; Wilkinson, Stuart K.; McClain, James S.; Chuchel, Bruce A.; Denton, Kevin M.

    2014-01-01

    From August 26 to September 5, 2011, the U.S. Geological Survey (USGS) collected more than 600 line-kilometers of shipborne magnetic data on Mono Lake, 20 line-kilometers of ground magnetic data on Paoha Island, 50 gravity stations on Paoha and Negit Islands, and 28 rock samples on Paoha and Negit Islands, in east-central California. Magnetic and gravity investigations were undertaken in Mono Lake to study regional crustal structures and to aid in understanding the geologic framework, in particular regarding potential geothermal resources and volcanic hazards throughout Mono Basin. Furthermore, shipborne magnetic data illuminate local structures in the upper crust beneath Mono Lake where geologic exposure is absent. Magnetic and gravity methods, which sense contrasting physical properties of the subsurface, are ideal for studying Mono Lake. Exposed rock units surrounding Mono Lake consist mainly of Quaternary alluvium, lacustrine sediment, aeolian deposits, basalt, and Paleozoic granitic and metasedimentary rocks (Bailey, 1989). At Black Point, on the northwest shore of Mono Lake, there is a mafic cinder cone that was produced by a subaqueous eruption around 13.3 ka. Within Mono Lake there are several small dacite cinder cones and flows, forming Negit Island and part of Paoha Island, which also host deposits of Quaternary lacustrine sediments. The typical density and magnetic properties of young volcanic rocks contrast with those of the lacustrine sediment, enabling us to map their subsurface extent.

  15. Tropical Gravity Wave Momentum Fluxes and Latent Heating Distributions

    NASA Technical Reports Server (NTRS)

    Geller, Marvin A.; Zhou, Tiehan; Love, Peter T.

    2015-01-01

    Recent satellite determinations of global distributions of absolute gravity wave (GW) momentum fluxes in the lower stratosphere show maxima over the summer subtropical continents and little evidence of GW momentum fluxes associated with the intertropical convergence zone (ITCZ). This seems to be at odds with parameterizations forGWmomentum fluxes, where the source is a function of latent heating rates, which are largest in the region of the ITCZ in terms of monthly averages. The authors have examined global distributions of atmospheric latent heating, cloud-top-pressure altitudes, and lower-stratosphere absolute GW momentum fluxes and have found that monthly averages of the lower-stratosphere GW momentum fluxes more closely resemble the monthly mean cloud-top altitudes rather than the monthly mean rates of latent heating. These regions of highest cloud-top altitudes occur when rates of latent heating are largest on the time scale of cloud growth. This, plus previously published studies, suggests that convective sources for stratospheric GW momentum fluxes, being a function of the rate of latent heating, will require either a climate model to correctly model this rate of latent heating or some ad hoc adjustments to account for shortcomings in a climate model's land-sea differences in convective latent heating.

  16. A system for conducting igneous petrology experiments under controlled redox conditions in reduced gravity

    NASA Technical Reports Server (NTRS)

    Williams, Richard J.

    1987-01-01

    The Space Shuttle and the planned Space Station will permit experimentation under conditions of reduced gravitational acceleration offering experimental petrologists the opportunity to study crystal growth, element distribution, and phase chemistry. In particular the confounding effects of macro and micro scale buoyancy-induced convection and crystal settling or flotation can be greatly reduced over those observed in experiments in the terrestrial laboratory. Also, for experiments in which detailed replication of the environment is important, the access to reduced gravity will permit a more complete simulation of processes that may have occurred on asteroids or in free space. A technique that was developed to control, measure, and manipulate oxygen fugacities with small quantities of gas which are recirculated over the sample. This system could be adaptable to reduced gravity space experiments requiring redox control.

  17. Glacier mass balance in high-arctic areas with anomalous gravity

    NASA Astrophysics Data System (ADS)

    Sharov, A.; Rieser, D.; Nikolskiy, D.

    2012-04-01

    graphically represented in the reference model geometry using Russian gravimetric maps 1:1000000 (1980s), ArcGP grid (2008) and GOCE gravity field data (Release 3, 2009-2011). 25-year long records of daily precipitation obtained from 38 coastal stations were involved in the causality analysis. Strong positive distance-weighted correlation was discovered between the magnitude of geopotential and gravity gradient on one hand and the precipitation amount, annual number of precipitation "events" and glacier elevation changes on the other, while it was noted that the correlation decreases in humid and mountainous areas. Relevant analytical and geophysical explanations were provided and tested using the basic concepts of hydrostatic stress, lapse rate and non-orographic gradient precipitation. It was concluded that the gravitational impact on the mass balance of arctic maritime ice caps is threefold. 1) Lateral variations of gravity influence directly the ambient lapse rate thereby modulating the atmospheric stability and leading to the increased intensity and frequency of heavy snowfalls over the areas with positive gravity anomalies. 2) Glacier ice deformation, flow, calving and meltwater runoff are gravity-driven phenomena, and the removal of glacier ice is closely interrelated with geopotential variations nearby. 3) Gravity anomalies affect processes of sea ice grow, drift and consolidation resulting in generally lower concentration and lesser thickness of the sea ice found in the aquatories with positive gravity. The advection of moist air to insular ice caps facilitates sea-effect snow events and makes glacier mass balance more positive. The effect is enhanced when the air mass advects toward the centre of positive anomaly. The idea about gradient (deviatoric) precipitation and related cryogravic processes does not contradict to the concept of gravity waves and has some analogy with the hypothesis on "ice lichens" devised by E.Gernet 80 years ago. Further analogies can be

  18. Gravity waves

    NASA Technical Reports Server (NTRS)

    Fritts, David

    1987-01-01

    Gravity waves contributed to the establishment of the thermal structure, small scale (80 to 100 km) fluctuations in velocity (50 to 80 m/sec) and density (20 to 30%, 0 to peak). Dominant gravity wave spectrum in the middle atmosphere: x-scale, less than 100 km; z-scale, greater than 10 km; t-scale, less than 2 hr. Theorists are beginning to understand middle atmosphere motions. There are two classes: Planetary waves and equatorial motions, gravity waves and tidal motions. The former give rise to variability at large scales, which may alter apparent mean structure. Effects include density and velocity fluctuations, induced mean motions, and stratospheric warmings which lead to the breakup of the polar vortex and cooling of the mesosphere. On this scale are also equatorial quasi-biennial and semi-annual oscillations. Gravity wave and tidal motions produce large rms fluctuations in density and velocity. The magnitude of the density fluctuations compared to the mean density is of the order of the vertical wavelength, which grows with height. Relative density fluctuations are less than, or of the order of 30% below the mesopause. Such motions may cause significant and variable convection, and wind shear. There is a strong seasonal variation in gravity wave amplitude. Additional observations are needed to address and quantify mean and fluctuation statistics of both density and mean velocity, variability of the mean and fluctuations, and to identify dominant gravity wave scales and sources as well as causes of variability, both temporal and geographic.

  19. Thickness and geometry of Cenozoic deposits in California Wash area, Nevada, based on gravity and seismic-reflection data

    USGS Publications Warehouse

    Langenheim, V.E.; Miller, J.J.; Page, W.R.; Grow, J.A.

    2001-01-01

    Gravity and seismic-reflection data provide insights into the subsurface stratigraphy and structure of the California Wash area of southern Nevada. This area is part of the Lower Colorado flow system and stratigraphic and structural data are important inputs into developing the hydrogeologic framework. These data indicate that the basin beneath California Wash reaches depths of 2-3 km. The eastern margin of the basin coincides with a system of young (Quaternary and late Tertiary) faults, although both seismic and gravity data indicate that the major basin-bounding fault is 2-3 km west of the mapped young faults. Dry Lake Valley, the adjacent valley to the west, is characterized by thinner basin fill. The basin configuration beneath both California Wash and Dry Lake Valleys based on the inversion of gravity data is unconstrained because of the lack of gravity stations north of 36030?. Broad aeromagnetic anomalies beneath pre-Cenozoic basement in the Muddy Mountains and Arrow Canyon Range reflect Precambrian basement at depths of ~ 5 km. These rocks are probably barriers to ground-water flow,except where fractured.

  20. Modulation of Internal Estimates of Gravity during and after Prolonged Roll-Tilts

    PubMed Central

    Tarnutzer, Alexander A.; Bertolini, Giovanni; Bockisch, Christopher J.; Straumann, Dominik; Marti, Sarah

    2013-01-01

    Perceived direction of gravity, as assessed by the subjective visual vertical (SVV), shows roll-angle dependent errors that drift over time and a bias upon return to upright. According to Bayesian observer theory, the estimated direction of gravity is derived from the posterior probability distribution by combining sensory input and prior knowledge about earth-vertical in a statistically optimal fashion. Here we aimed to further characterize the stability of SVV during and after prolonged roll-tilts. Specifically we asked whether the post-tilt bias is related to the drift pattern while roll-tilted. Twenty-nine healthy human subjects (23-56yo) repetitively adjusted a luminous arrow to the SVV over periods of 5min while upright, roll-tilted (±45°, ±90°), and immediately after returning to upright. Significant (p<0.05) drifts (median absolute drift-amplitude: 10°/5min) were found in 71% (±45°) and 78% (±90°) of runs. At ±90° roll-tilt significant increases in absolute adjustment errors were more likely (76%), whereas significant increases (56%) and decreases (44%) were about equally frequent at ±45°. When returning to upright, an initial bias towards the previous roll-position followed by significant exponential decay (median time-constant: 71sec) was noted in 47% of all runs (all subjects pooled). No significant correlations were found between the drift pattern during and immediately after prolonged roll-tilt. We conclude that the SVV is not stable during and after prolonged roll-tilt and that the direction and magnitude of drift are individually distinct and roll-angle-dependent. Likely sensory and central adaptation and random-walk processes contribute to drift while roll-tilted. Lack of correlation between the drift and the post-tilt bias suggests that it is not the inaccuracy of the SVV estimate while tilted that determines post-tilt bias, but rather the previous head-roll orientation relative to gravity. We therefore favor central adaptation, most