Sample records for australian square-kilometre-array pathfinder

  1. Building Educational Programs for the Australian Square Kilometre Array Pathfinder

    NASA Astrophysics Data System (ADS)

    Hollow, R.; Hobbs, G.

    2010-08-01

    The Australian Square Kilometre Array Pathfinder (ASKAP) will be an array of 36 antennas in Western Australia, each 12-m in diameter, and is due for operation in 2013. With a large instantaneous field-of-view ASKAP will survey the whole sky faster than existing radio telescopes, producing massive data sets. Government funding for ASKAP was contingent on it being available for education purposes, providing an exciting opportunity to develop innovative education projects for schools and citizen science. Building on the PULSE@Parkes program we plan to have a range of activities and resources, providing scope for student investigations. Challenges and educational opportunities are discussed.

  2. A pilot survey for transients and variables with the Australian Square Kilometre Array Pathfinder

    NASA Astrophysics Data System (ADS)

    Bhandari, S.; Bannister, K. W.; Murphy, T.; Bell, M.; Raja, W.; Marvil, J.; Hancock, P. J.; Whiting, M.; Flynn, C. M.; Collier, J. D.; Kaplan, D. L.; Allison, J. R.; Anderson, C.; Heywood, I.; Hotan, A.; Hunstead, R.; Lee-Waddell, K.; Madrid, J. P.; McConnell, D.; Popping, A.; Rhee, J.; Sadler, E.; Voronkov, M. A.

    2018-05-01

    We present a pilot search for variable and transient sources at 1.4 GHz with the Australian Square Kilometre Array Pathfinder (ASKAP). The search was performed in a 30 deg2 area centred on the NGC 7232 galaxy group over 8 epochs and observed with a near-daily cadence. The search yielded nine potential variable sources, rejecting the null hypothesis that the flux densities of these sources do not change with 99.9% confidence. These nine sources displayed flux density variations with modulation indices m ≥ 0.1 above our flux density limit of ˜1.5 mJy. They are identified to be compact AGN/quasars or galaxies hosting an AGN, whose variability is consistent with refractive interstellar scintillation. We also detect a highly variable source with modulation index m > 0.5 over a time interval of a decade between the Sydney University Molonglo Sky Survey (SUMSS) and our latest ASKAP observations. We find the source to be consistent with the properties of long-term variability of a quasar. No transients were detected on timescales of days and we place an upper limit ρt < 0.01 deg-2 with 95% confidence for non-detections on near-daily timescales. The future VAST-Wide survey with 36-ASKAP dishes will probe the transient phase space with similar cadence to our pilot survey, but better sensitivity, and will detect and monitor rarer brighter events.

  3. The Australian SKA Pathfinder: project update and initial operations

    NASA Astrophysics Data System (ADS)

    Schinckel, Antony E. T.; Bock, Douglas C.-J.

    2016-08-01

    The Australian Square Kilometre Array Pathfinder (ASKAP) will be the fastest dedicated cm-wave survey telescope, and will consist of 36 12-meter 3-axis antennas, each with a large chequerboard phased array feed (PAF) receiver operating between 0.7 and 1.8 GHz, and digital beamforming prior to correlation. The large raw data rates involved ( 100 Tb/sec), and the need to do pipeline processing, has led to the antenna incorporating a third axis to fix the parallactic angle with respect to the entire optical system (blockages and phased array feed). It also results in innovative technical solutions to the data transport and processing issues. ASKAP is located at the Murchison Radio-astronomy Observatory (MRO), a new observatory developed for the Square Kilometre Array (SKA), 315 kilometres north-east of Geraldton, Western Australia. The MRO also hosts the SKA low frequency pathfinder instrument, the Murchison Widefield Array and will host the initial low frequency instrument of the SKA, SKA1-Low. Commissioning of ASKAP using six antennas equipped with first-generation PAFs is now complete and installation of second-generation PAFs and digital systems is underway. In this paper we review technical progress and commissioning to date, and refer the reader to relevant technical and scientific publications.

  4. Extragalactic radio surveys in the pre-Square Kilometre Array era

    PubMed Central

    2017-01-01

    The era of the Square Kilometre Array is almost upon us, and pathfinder telescopes are already in operation. This brief review summarizes our current knowledge of extragalactic radio sources, accumulated through six decades of continuum surveys at the low-frequency end of the electromagnetic spectrum and the extensive complementary observations at other wavelengths necessary to gain this understanding. The relationships between radio survey data and surveys at other wavelengths are discussed. Some of the outstanding questions are identified and prospects over the next few years are outlined. PMID:28791175

  5. Radio Continuum Surveys with Square Kilometre Array Pathfinders

    NASA Astrophysics Data System (ADS)

    Norris, Ray P.; Afonso, J.; Bacon, D.; Beck, Rainer; Bell, Martin; Beswick, R. J.; Best, Philip; Bhatnagar, Sanjay; Bonafede, Annalisa; Brunetti, Gianfranco; Budavári, Tamás; Cassano, Rossella; Condon, J. J.; Cress, Catherine; Dabbech, Arwa; Feain, I.; Fender, Rob; Ferrari, Chiara; Gaensler, B. M.; Giovannini, G.; Haverkorn, Marijke; Heald, George; Van der Heyden, Kurt; Hopkins, A. M.; Jarvis, M.; Johnston-Hollitt, Melanie; Kothes, Roland; Van Langevelde, Huib; Lazio, Joseph; Mao, Minnie Y.; Martínez-Sansigre, Alejo; Mary, David; Mcalpine, Kim; Middelberg, E.; Murphy, Eric; Padovani, P.; Paragi, Zsolt; Prandoni, I.; Raccanelli, A.; Rigby, Emma; Roseboom, I. G.; Röttgering, H.; Sabater, Jose; Salvato, Mara; Scaife, Anna M. M.; Schilizzi, Richard; Seymour, N.; Smith, Dan J. B.; Umana, Grazia; Zhao, G.-B.; Zinn, Peter-Christian

    2013-03-01

    In the lead-up to the Square Kilometre Array (SKA) project, several next-generation radio telescopes and upgrades are already being built around the world. These include APERTIF (The Netherlands), ASKAP (Australia), e-MERLIN (UK), VLA (USA), e-EVN (based in Europe), LOFAR (The Netherlands), MeerKAT (South Africa), and the Murchison Widefield Array. Each of these new instruments has different strengths, and coordination of surveys between them can help maximise the science from each of them. A radio continuum survey is being planned on each of them with the primary science objective of understanding the formation and evolution of galaxies over cosmic time, and the cosmological parameters and large-scale structures which drive it. In pursuit of this objective, the different teams are developing a variety of new techniques, and refining existing ones. To achieve these exciting scientific goals, many technical challenges must be addressed by the survey instruments. Given the limited resources of the global radio-astronomical community, it is essential that we pool our skills and knowledge. We do not have sufficient resources to enjoy the luxury of re-inventing wheels. We face significant challenges in calibration, imaging, source extraction and measurement, classification and cross-identification, redshift determination, stacking, and data-intensive research. As these instruments extend the observational parameters, we will face further unexpected challenges in calibration, imaging, and interpretation. If we are to realise the full scientific potential of these expensive instruments, it is essential that we devote enough resources and careful study to understanding the instrumental effects and how they will affect the data. We have established an SKA Radio Continuum Survey working group, whose prime role is to maximise science from these instruments by ensuring we share resources and expertise across the projects. Here we describe these projects, their science goals

  6. The Square Kilometre Array

    NASA Technical Reports Server (NTRS)

    Huynh, Minh; Lazio, Joseph

    2011-01-01

    The Square Kilometre Array (SKA) will be the premier instrument to study radiation at centimetre and metre wavelengths from the cosmos, and in particular neutral hydrogen, the most abundant element in the universe. The SKA will probe the dawn of galaxy formation as well as allow advances in many other areas of astronomy, such as fundamental physics, astro-biology and cosmology. The SKA will have a collecting area of up to one million square metres spread over at least 3000 km, providing a collecting area more than twenty times greater than the current largest radio telescope. Its field of view on the sky will be several tens of square degrees with potentially several large (100 square degrees) independent beams at the lower frequencies, providing a survey speed many thousands of times greater than current facilities. This paper summarises the key science drivers of the SKA and provides an update on the international project.

  7. The Australian SKA Pathfinder: operations management and user engagement

    NASA Astrophysics Data System (ADS)

    Harvey-Smith, Lisa

    2016-07-01

    This paper describes the science operations model for the Australian Square Kilometre Array Pathfinder (ASKAP) telescope. ASKAP is a radio interferometer currently being commissioned in Western Australia. It will be operated by a dedicated team of observatory staff with the support of telescope monitoring, control and scheduling software. These tools, as well as the proposal tools and data archive will enable the telescope to operate with little direct input from the astronomy user. The paper also discusses how close engagement with the telescope user community has been maintained throughout the ASKAP construction and commissioning phase, leading to positive outcomes including early input into the design of telescope systems and a vibrant early science program.

  8. Science with the Square Kilometre Array

    NASA Technical Reports Server (NTRS)

    Lazio, Joseph; Huynh, Minh

    2010-01-01

    The Square Kilometre Array (SKA) is the centimeter- and meter-wavelength telescope for the 21st Century. Its Key Science Projects are (a) The end of the Dark Ages, involving searches for an H i signature and the first metalrich systems; (b) Testing theories of gravitation using an array of pulsars to search for gravitational waves and relativistic binaries to probe the strong-field regime; (c) Observations of H i to a redshift z 2 from which to study the evolution of galaxies and dark energy. (d) Astrobiology including planetary formation within protoplanetary disks; and (c) The origin and evolution of cosmic magnetism, both within the Galaxy and in intergalactic space. The SKA will operate over the wavelength range of at least 1.2 cm to 4 m (70 MHz to 25 GHz), providing milliarcsecond resolution at the shortest wavelengths.

  9. Gemini Follow-up of Two Massive H I Clouds Discovered with the Australian Square Kilometer Array Pathfinder

    NASA Astrophysics Data System (ADS)

    Madrid, Juan P.; Lee-Waddell, Karen; Serra, Paolo; Koribalski, Bärbel S.; Schirmer, Mischa; Spekkens, Kristine; Wang, Jing

    2018-02-01

    Using the Gemini Multi Object Spectrograph (GMOS) we search for optical counterparts of two massive (∼109 M ⊙) neutral hydrogen clouds near the spiral galaxy IC 5270, located in the outskirts of the IC 1459 group. These two H I clouds were recently discovered using the Australian Square Kilometer Array Pathfinder (ASKAP). Two low surface brightness optical counterparts to one of these H I clouds are identified in the new Gemini data that reaches down to magnitudes of ∼27.5 mag in the g-band. The observed H I mass-to-light ratio derived with these new data, {M}{{H}{{I}}}/{L}g=242, is among the highest reported to date. We are also able to rule out that the two H I clouds are dwarf companions of IC 5270. Tidal interactions and ram pressure stripping are plausible explanations for the physical origin of these two clouds.

  10. An Overview of the Square Kilometre Array

    NASA Technical Reports Server (NTRS)

    Huynh, Minh T.; Lazio, Joseph

    2013-01-01

    The Square Kilometre Array (SKA) will be the premier instrument to study radiation at centimetre and metre wavelengths from the cosmos, and in particular hydrogen, the most abundant element in the universe. The SKA will probe the dawn of galaxy formation as well as allow advances in many other areas of astronomy, such as fundamental physics, astrobiology and cosmology. Phase 1, which will be about 10% of the full SKA collecting area, will be built in Australia and South Africa. This paper describes the key science drivers of the SKA, provides an update on recent SKA Organisation activities and summarises the baseline design for Phase 1.

  11. The Square Kilometre Array Epoch of Reionisation and Cosmic Dawn Experiment

    NASA Astrophysics Data System (ADS)

    Trott, Cathryn M.

    2018-05-01

    The Square Kilometre Array (SKA) Epoch of Reionisation and Cosmic Dawn (EoR/CD) experiments aim to explore the growth of structure and production of ionising radiation in the first billion years of the Universe. Here I describe the experiments planned for the future low-frequency components of the Observatory, and work underway to define, design and execute these programs.

  12. Expected Science Performance of the Square Kilometre Array Phase 1 (SKA1)

    NASA Astrophysics Data System (ADS)

    Bourke, Tyler; Braun, Robert; Bonaldi, Anna; Garcia-Miro, Cristina; Keane, Evan; Wagg, Jeff; SKAO Science Team

    2018-01-01

    The Square Kilometre Array (SKA) will be the world’s largest radio telescope when Phase 1 (SKA1) is completed in the next decade. The past few years have seen great progress toward this goal, through extensive design activities, with construction to start before the end of this decade, and early operations anticipated to begin around 2026. This poster describes the SKA and presents the expected performance and capabilities of SKA1 based on the modelling and proto-typing to date.

  13. Square Kilometre Array Telescope—Precision Reference Frequency Synchronisation via 1f-2f Dissemination

    PubMed Central

    Wang, B.; Zhu, X.; Gao, C.; Bai, Y.; Dong, J. W.; Wang, L. J.

    2015-01-01

    The Square Kilometre Array (SKA) project is an international effort to build the world’s largest radio telescope, with a one-square-kilometre collecting area. In addition to its ambitious scientific objectives, such as probing cosmic dawn and the cradle of life, the SKA demands several revolutionary technological breakthroughs, such as ultra-high precision synchronisation of the frequency references for thousands of antennas. In this report, with the purpose of application to the SKA, we demonstrate a frequency reference dissemination and synchronisation scheme in which the phase-noise compensation function is applied at the client site. Hence, one central hub can be linked to a large number of client sites, thus forming a star-shaped topology. As a performance test, a 100-MHz reference frequency signal from a hydrogen maser (H-maser) clock is disseminated and recovered at two remote sites. The phase-noise characteristics of the recovered reference frequency signal coincide with those of the H-maser source and satisfy the SKA requirements. PMID:26349544

  14. LUNASKA experiments using the Australia Telescope Compact Array to search for ultrahigh energy neutrinos and develop technology for the lunar Cherenkov technique

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

    James, C. W.; Protheroe, R. J.; Ekers, R. D.

    2010-02-15

    We describe the design, performance, sensitivity and results of our recent experiments using the Australia Telescope Compact Array (ATCA) for lunar Cherenkov observations with a very wide (600 MHz) bandwidth and nanosecond timing, including a limit on an isotropic neutrino flux. We also make a first estimate of the effects of small-scale surface roughness on the effective experimental aperture, finding that contrary to expectations, such roughness will act to increase the detectability of near-surface events over the neutrino energy-range at which our experiment is most sensitive (though distortions to the time-domain pulse profile may make identification more difficult). The aimmore » of our 'Lunar UHE Neutrino Astrophysics using the Square Kilometre Array' (LUNASKA) project is to develop the lunar Cherenkov technique of using terrestrial radio telescope arrays for ultrahigh energy (UHE) cosmic ray (CR) and neutrino detection, and, in particular, to prepare for using the Square Kilometre Array (SKA) and its path-finders such as the Australian SKA Pathfinder (ASKAP) and the Low Frequency Array (LOFAR) for lunar Cherenkov experiments.« less

  15. Cosmology with the Square Kilometre Array by SKA-Japan

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

    Yamauchi, Daisuke; Ichiki, Kiyotomo; Kohri, Kazunori

    In the past several decades, the standard cosmological model has been established and its parameters have been measured to a high precision, while there are still many fundamental questions in cosmology; such as the physics in the very early universe, the origin of the cosmic acceleration, and the nature of dark matter. The forthcoming radio telescope, the Square Kilometre Array (SKA), which will be the world's largest, will be able to open a new frontier in cosmology and will be one of the most powerful tools for cosmology in the coming decade. The cosmological surveys conducted by the SKA wouldmore » have the potential not only to answer these fundamental questions but also deliver precision cosmology. In this article we briefly review the role of the SKA from the viewpoint of modern cosmology. Furthermore, the cosmological science led by the SKA-Japan Consortium (SKA-JP) Cosmology Science Working Group is also discussed.« less

  16. Cosmology with the Square Kilometre Array by SKA-Japan

    DOE PAGES

    Yamauchi, Daisuke; Ichiki, Kiyotomo; Kohri, Kazunori; ...

    2016-10-17

    In the past several decades, the standard cosmological model has been established and its parameters have been measured to a high precision, while there are still many fundamental questions in cosmology; such as the physics in the very early universe, the origin of the cosmic acceleration, and the nature of dark matter. The forthcoming radio telescope, the Square Kilometre Array (SKA), which will be the world's largest, will be able to open a new frontier in cosmology and will be one of the most powerful tools for cosmology in the coming decade. The cosmological surveys conducted by the SKA wouldmore » have the potential not only to answer these fundamental questions but also deliver precision cosmology. In this article we briefly review the role of the SKA from the viewpoint of modern cosmology. Furthermore, the cosmological science led by the SKA-Japan Consortium (SKA-JP) Cosmology Science Working Group is also discussed.« less

  17. DETECTION OF FAST RADIO TRANSIENTS WITH MULTIPLE STATIONS: A CASE STUDY USING THE VERY LONG BASELINE ARRAY

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

    Thompson, David R.; Wagstaff, Kiri L.; Majid, Walid A.

    2011-07-10

    Recent investigations reveal an important new class of transient radio phenomena that occur on submillisecond timescales. Often, transient surveys' data volumes are too large to archive exhaustively. Instead, an online automatic system must excise impulsive interference and detect candidate events in real time. This work presents a case study using data from multiple geographically distributed stations to perform simultaneous interference excision and transient detection. We present several algorithms that incorporate dedispersed data from multiple sites, and report experiments with a commensal real-time transient detection system on the Very Long Baseline Array. We test the system using observations of pulsar B0329+54.more » The multiple-station algorithms enhanced sensitivity for detection of individual pulses. These strategies could improve detection performance for a future generation of geographically distributed arrays such as the Australian Square Kilometre Array Pathfinder and the Square Kilometre Array.« less

  18. Observation management challenges of the Square Kilometre Array

    NASA Astrophysics Data System (ADS)

    Bridger, Alan; Williams, Stewart J.; Nicol, Mark; Klaassen, Pamela; Thompson, Roger S.; Knapic, Cristina; Jerse, Giovanna; Orlati, Andrea; Messina, Marco; Valame, Snehal

    2016-07-01

    The Square Kilometre Array (SKA) will be the world's most advanced radio telescope, designed to explore some of the biggest questions in astronomy today, such as the epoch of re-ionization, the nature of gravity and the origins of cosmic magnetism. SKA1, the first phase of SKA construction, is currently being designed by a large team of experts world-wide. SKA1 comprises two telescopes: a 200-element dish interferometer in South Africa and a 130000-element dipole antenna aperture array in Australia. To enable the ground-breaking science of the SKA an advanced Observation Management system is required to support both the needs of the astronomical community users and the SKA Observatory staff. This system will ensure that the SKA realises its scientiffc aims and achieves optimal scientific throughput. This paper provides an overview of the design of the system that will accept proposals from SKA users, and result in the execution of the scripts that will obtain science data, taking in the stages of detailed preparation, planning and scheduling of the observations and onwards tracking. It describes the unique challenges of the differing requirements of two telescopes, one of which is very much a software telescope, including the need to schedule the data processing as well as the acquisition, and to react to both internally and externally discovered transient events. The scheduling of multiple parallel sub-array use is covered, along with the need to handle commensal observing - using the same data stream to satisfy the science goals of more than one project simultaneously. An international team from academia and industry, drawing on expertise and experience from previous telescope projects, the virtual observatory and comparable problems in industry, has been assembled to design the solution to this challenging but exciting problem.

  19. Spectral performance of Square Kilometre Array Antennas - II. Calibration performance

    NASA Astrophysics Data System (ADS)

    Trott, Cathryn M.; de Lera Acedo, Eloy; Wayth, Randall B.; Fagnoni, Nicolas; Sutinjo, Adrian T.; Wakley, Brett; Punzalan, Chris Ivan B.

    2017-09-01

    We test the bandpass smoothness performance of two prototype Square Kilometre Array (SKA) SKA1-Low log-periodic dipole antennas, SKALA2 and SKALA3 ('SKA Log-periodic Antenna'), and the current dipole from the Murchison Widefield Array (MWA) precursor telescope. Throughout this paper, we refer to the output complex-valued voltage response of an antenna when connected to a low-noise amplifier, as the dipole bandpass. In Paper I, the bandpass spectral response of the log-periodic antenna being developed for the SKA1-Low was estimated using numerical electromagnetic simulations and analysed using low-order polynomial fittings, and it was compared with the HERA antenna against the delay spectrum metric. In this work, realistic simulations of the SKA1-Low instrument, including frequency-dependent primary beam shapes and array configuration, are used with a weighted least-squares polynomial estimator to assess the ability of a given prototype antenna to perform the SKA Epoch of Reionisation (EoR) statistical experiments. This work complements the ideal estimator tolerances computed for the proposed EoR science experiments in Trott & Wayth, with the realized performance of an optimal and standard estimation (calibration) procedure. With a sufficient sky calibration model at higher frequencies, all antennas have bandpasses that are sufficiently smooth to meet the tolerances described in Trott & Wayth to perform the EoR statistical experiments, and these are primarily limited by an adequate sky calibration model and the thermal noise level in the calibration data. At frequencies of the Cosmic Dawn, which is of principal interest to SKA as one of the first next-generation telescopes capable of accessing higher redshifts, the MWA dipole and SKALA3 antenna have adequate performance, while the SKALA2 design will impede the ability to explore this era.

  20. Square Kilometre Array Science Data Processing

    NASA Astrophysics Data System (ADS)

    Nikolic, Bojan; SDP Consortium, SKA

    2014-04-01

    The Square Kilometre Array (SKA) is planned to be, by a large factor, the largest and most sensitive radio telescope ever constructed. The first phase of the telescope (SKA1), now in the design phase, will in itself represent a major leap in capabilities compared to current facilities. These advances are to a large extent being made possible by advances in available computer processing power so that that larger numbers of smaller, simpler and cheaper receptors can be used. As a result of greater reliance and demands on computing, ICT is becoming an ever more integral part of the telescope. The Science Data Processor is the part of the SKA system responsible for imaging, calibration, pulsar timing, confirmation of pulsar candidates, derivation of some further derived data products, archiving and providing the data to the users. It will accept visibilities at data rates at several TB/s and require processing power for imaging in range 100 petaFLOPS -- ~1 ExaFLOPS, putting SKA1 into the regime of exascale radio astronomy. In my talk I will present the overall SKA system requirements and how they drive these high data throughput and processing requirements. Some of the key challenges for the design of SDP are: - Identifying sufficient parallelism to utilise very large numbers of separate compute cores that will be required to provide exascale computing throughput - Managing efficiently the high internal data flow rates - A conceptual architecture and software engineering approach that will allow adaptation of the algorithms as we learn about the telescope and the atmosphere during the commissioning and operational phases - System management that will deal gracefully with (inevitably frequent) failures of individual units of the processing system In my talk I will present possible initial architectures for the SDP system that attempt to address these and other challenges.

  1. Scalable Data Mining and Archiving for the Square Kilometre Array

    NASA Astrophysics Data System (ADS)

    Jones, D. L.; Mattmann, C. A.; Hart, A. F.; Lazio, J.; Bennett, T.; Wagstaff, K. L.; Thompson, D. R.; Preston, R.

    2011-12-01

    As the technologies for remote observation improve, the rapid increase in the frequency and fidelity of those observations translates into an avalanche of data that is already beginning to eclipse the resources, both human and technical, of the institutions and facilities charged with managing the information. Common data management tasks like cataloging both data itself and contextual meta-data, creating and maintaining scalable permanent archive, and making data available on-demand for research present significant software engineering challenges when considered at the scales of modern multi-national scientific enterprises such as the upcoming Square Kilometre Array project. The NASA Jet Propulsion Laboratory (JPL), leveraging internal research and technology development funding, has begun to explore ways to address the data archiving and distribution challenges with a number of parallel activities involving collaborations with the EVLA and ALMA teams at the National Radio Astronomy Observatory (NRAO), and members of the Square Kilometre Array South Africa team. To date, we have leveraged the Apache OODT Process Control System framework and its catalog and archive service components that provide file management, workflow management, resource management as core web services. A client crawler framework ingests upstream data (e.g., EVLA raw directory output), identifies its MIME type and automatically extracts relevant metadata including temporal bounds, and job-relevant/processing information. A remote content acquisition (pushpull) service is responsible for staging remote content and handing it off to the crawler framework. A science algorithm wrapper (called CAS-PGE) wraps underlying code including CASApy programs for the EVLA, such as Continuum Imaging and Spectral Line Cube generation, executes the algorithm, and ingests its output (along with relevant extracted metadata). In addition to processing, the Process Control System has been leveraged to provide data

  2. A user interface framework for the Square Kilometre Array: concepts and responsibilities

    NASA Astrophysics Data System (ADS)

    Marassi, Alessandro; Brajnik, Giorgio; Nicol, Mark; Alberti, Valentina; Le Roux, Gerhard

    2016-07-01

    The Square Kilometre Array (SKA) project is responsible for developing the SKA Observatory, the world's largest radio telescope, with eventually over a square kilometre of collecting area and including a general headquarters as well as two radio telescopes: SKA1-Mid in South Africa and SKA1-Low in Australia. The SKA project consists of a number of subsystems (elements) among which the Telescope Manager (TM) is the one involved in controlling and monitoring the SKA telescopes. The TM element has three primary responsibilities: management of astronomical observations, management of telescope hardware and software subsystems, management of data to support system operations and all stakeholders (operators, maintainers, engineers and science users) in achieving operational, maintenance and engineering goals. Operators, maintainers, engineers and science users will interact with TM via appropriate user interfaces (UI). The TM UI framework envisaged is a complete set of general technical solutions (components, technologies and design information) for implementing a generic computing system (UI platform). Such a system will enable UI components to be instantiated to allow for human interaction via screens, keyboards, mouse and to implement the necessary logic for acquiring or deriving the information needed for interaction. It will provide libraries and specific Application Programming Interfaces (APIs) to implement operator and engineer interactive interfaces. This paper will provide a status update of the TM UI framework, UI platform and UI components design effort, including the technology choices, and discuss key challenges in the TM UI architecture, as well as our approaches to addressing them.

  3. Phase Synchronization for the Mid-Frequency Square Kilometre Array Telescope

    NASA Astrophysics Data System (ADS)

    Schediwy, Sascha; Gozzard, David; Stobie, Simon; Gravestock, Charles; Whitaker, Richard; Alachkar, Bassem; Malan, Sias; Boven, Paul; Grainge, Keith

    2018-01-01

    The Square Kilometre Array (SKA) project is an international effort to build the world’s most sensitive radio telescope operating in the 50 MHz to 14 GHz frequency range. Construction of the SKA has been divided into phases, with the first phase (SKA1) accounting for the first 10% of the telescope's receiving capacity. During SKA1, a low-frequency aperture array comprising over a hundred thousand individual dipole antenna elements will be constructed in Western Australia (SKA1-low), while an array of 197 parabolic-dish antennas, incorporating the 64 dishes of MeerKAT, will be constructed in South Africa (SKA1-mid).Radio telescope arrays such as the SKA require phase-coherent reference signals to be transmitted to each antenna site in the array. In the case of the SKA1-mid, these reference signals will be generated at a central site and transmitted to the antenna sites via fiber-optic cables up to 175 km in length. Environmental perturbations affect the optical path length of the fiber and act to degrade the phase stability of the reference signals received at the antennas, which has the ultimate effect of reducing the fidelity and dynamic range of the data.Since 2011, researchers at the University of Western Australia (UWA) have led the development of an actively-stabilized phase-synchronization system designed specifically to meet the scientific needs and technical challenges of the SKA telescope. Recently this system has been select as the official phase synchronization system for the SKA1-mid telescope. The system is an evolution of Atacama Large Millimeter Array’s distributed ‘photonic local oscillator system’, incorporating key advances made by the international frequency metrology community over the last decade, as well as novel innovations developed by UWA researchers.In this presentation I will describe the technical details of the system; outline how the system's performance was tested using metrology techniques in a laboratory setting, on 186 km

  4. Dynamic scheduling and planning parallel observations on large Radio Telescope Arrays with the Square Kilometre Array in mind

    NASA Astrophysics Data System (ADS)

    Buchner, Johannes

    2011-12-01

    Scheduling, the task of producing a time table for resources and tasks, is well-known to be a difficult problem the more resources are involved (a NP-hard problem). This is about to become an issue in Radio astronomy as observatories consisting of hundreds to thousands of telescopes are planned and operated. The Square Kilometre Array (SKA), which Australia and New Zealand bid to host, is aiming for scales where current approaches -- in construction, operation but also scheduling -- are insufficent. Although manual scheduling is common today, the problem is becoming complicated by the demand for (1) independent sub-arrays doing simultaneous observations, which requires the scheduler to plan parallel observations and (2) dynamic re-scheduling on changed conditions. Both of these requirements apply to the SKA, especially in the construction phase. We review the scheduling approaches taken in the astronomy literature, as well as investigate techniques from human schedulers and today's observatories. The scheduling problem is specified in general for scientific observations and in particular on radio telescope arrays. Also taken into account is the fact that the observatory may be oversubscribed, requiring the scheduling problem to be integrated with a planning process. We solve this long-term scheduling problem using a time-based encoding that works in the very general case of observation scheduling. This research then compares algorithms from various approaches, including fast heuristics from CPU scheduling, Linear Integer Programming and Genetic algorithms, Branch-and-Bound enumeration schemes. Measures include not only goodness of the solution, but also scalability and re-scheduling capabilities. In conclusion, we have identified a fast and good scheduling approach that allows (re-)scheduling difficult and changing problems by combining heuristics with a Genetic algorithm using block-wise mutation operations. We are able to explain and eradicate two problems in the

  5. Scalable, efficient ASICS for the square kilometre array: From A/D conversion to central correlation

    NASA Astrophysics Data System (ADS)

    Schmatz, M. L.; Jongerius, R.; Dittmann, G.; Anghel, A.; Engbersen, T.; van Lunteren, J.; Buchmann, P.

    2014-05-01

    The Square Kilometre Array (SKA) is a future radio telescope, currently being designed by the worldwide radio-astronomy community. During the first of two construction phases, more than 250,000 antennas will be deployed, clustered in aperture-array stations. The antennas will generate 2.5 Pb/s of data, which needs to be processed in real time. For the processing stages from A/D conversion to central correlation, we propose an ASIC solution using only three chip architectures. The architecture is scalable - additional chips support additional antennas or beams - and versatile - it can relocate its receiver band within a range of a few MHz up to 4GHz. This flexibility makes it applicable to both SKA phases 1 and 2. The proposed chips implement an antenna and station processor for 289 antennas with a power consumption on the order of 600W and a correlator, including corner turn, for 911 stations on the order of 90 kW.

  6. Searching for Extraterrestrial Intelligence with the Square Kilometre Array

    NASA Astrophysics Data System (ADS)

    Siemion, A.; Benford, J.; Cheng-Jin, J.; Chennamangalam, J.; Cordes, J. M.; Falcke, H. D. E.; Garrington, S. T.; Garrett, M. A.; Gurvits, L.; Hoare, M.; Korpela, E.; Lazio, J.; Messerschmitt, D.; Morrison, I.; O'Brien, T.; Paragi, Z.; Penny, A.; Spitler, L.; Tarter, J.; Werthimer, D.

    2015-04-01

    The vast collecting area of the Square Kilometre Array (SKA), harnessed by sensitive receivers, flexible digital electronics and increased computational capacity, could permit the most sensitive and exhaustive search for technologically-produced radio emission from advanced extraterrestrial intelligence (SETI) ever performed. For example, SKA1-MID will be capable of detecting a source roughly analogous to terrestrial high-power radars (e.g. air route surveillance or ballistic missile warning radars, EIRP (EIRP = equivalent isotropic radiated power, ~10^17 erg sec^-1) at 10 pc in less than 15 minutes, and with a modest four beam SETI observing system could, in one minute, search every star in the primary beam out to ~100 pc for radio emission comparable to that emitted by the Arecibo Planetary Radar (EIRP ~2 x 10^20 erg sec^-1). The flexibility of the signal detection systems used for SETI searches with the SKA will allow new algorithms to be employed that will provide sensitivity to a much wider variety of signal types than previously searched for. Here we discuss the astrobiological and astrophysical motivations for radio SETI and describe how the technical capabilities of the SKA will explore the radio SETI parameter space. We detail several conceivable SETI experimental programs on all components of SKA1, including commensal, primary-user, targeted and survey programs and project the enhancements to them possible with SKA2. We also discuss target selection criteria for these programs, and in the case of commensal observing, how the varied use cases of other primary observers can be used to full advantage for SETI.

  7. The Detection of an Extremely Bright Fast Radio Burst in a Phased Array Feed Survey

    NASA Astrophysics Data System (ADS)

    Bannister, K. W.; Shannon, R. M.; Macquart, J.-P.; Flynn, C.; Edwards, P. G.; O'Neill, M.; Osłowski, S.; Bailes, M.; Zackay, B.; Clarke, N.; D'Addario, L. R.; Dodson, R.; Hall, P. J.; Jameson, A.; Jones, D.; Navarro, R.; Trinh, J. T.; Allison, J.; Anderson, C. S.; Bell, M.; Chippendale, A. P.; Collier, J. D.; Heald, G.; Heywood, I.; Hotan, A. W.; Lee-Waddell, K.; Madrid, J. P.; Marvil, J.; McConnell, D.; Popping, A.; Voronkov, M. A.; Whiting, M. T.; Allen, G. R.; Bock, D. C.-J.; Brodrick, D. P.; Cooray, F.; DeBoer, D. R.; Diamond, P. J.; Ekers, R.; Gough, R. G.; Hampson, G. A.; Harvey-Smith, L.; Hay, S. G.; Hayman, D. B.; Jackson, C. A.; Johnston, S.; Koribalski, B. S.; McClure-Griffiths, N. M.; Mirtschin, P.; Ng, A.; Norris, R. P.; Pearce, S. E.; Phillips, C. J.; Roxby, D. N.; Troup, E. R.; Westmeier, T.

    2017-05-01

    We report the detection of an ultra-bright fast radio burst (FRB) from a modest, 3.4-day pilot survey with the Australian Square Kilometre Array Pathfinder. The survey was conducted in a wide-field fly’s-eye configuration using the phased-array-feed technology deployed on the array to instantaneously observe an effective area of 160 deg2, and achieve an exposure totaling 13200 deg2 hr . We constrain the position of FRB 170107 to a region 8\\prime × 8\\prime in size (90% containment) and its fluence to be 58 ± 6 Jy ms. The spectrum of the burst shows a sharp cutoff above 1400 MHz, which could be due to either scintillation or an intrinsic feature of the burst. This confirms the existence of an ultra-bright (> 20 Jy ms) population of FRBs.

  8. The prospects of pulsar timing with new-generation radio telescopes and the Square Kilometre Array

    NASA Astrophysics Data System (ADS)

    Stappers, B. W.; Keane, E. F.; Kramer, M.; Possenti, A.; Stairs, I. H.

    2018-05-01

    Pulsars are highly magnetized and rapidly rotating neutron stars. As they spin, the lighthouse-like beam of radio emission from their magnetic poles sweeps across the Earth with a regularity approaching that of the most precise clocks known. This precision combined with the extreme environments in which they are found, often in compact orbits with other neutron stars and white dwarfs, makes them excellent tools for studying gravity. Present and near-future pulsar surveys, especially those using the new generation of telescopes, will find more extreme binary systems and pulsars that are more precise `clocks'. These telescopes will also greatly improve the precision to which we can measure the arrival times of the pulses. The Square Kilometre Array will revolutionize pulsar searches and timing precision. The increased number of sources will reveal rare sources, including possibly a pulsar-black hole binary, which can provide the most stringent tests of strong-field gravity. The improved timing precision will reveal new phenomena and also allow us to make a detection of gravitational waves in the nanohertz frequency regime. It is here where we expect to see the signature of the binary black holes that are formed as galaxies merge throughout cosmological history. This article is part of a discussion meeting issue `The promises of gravitational-wave astronomy'.

  9. An innovative, highly sensitive receiver system for the Square Kilometre Array Mid Radio Telescope

    NASA Astrophysics Data System (ADS)

    Tan, Gie Han; Lehmensiek, Robert; Billade, Bhushan; Caputa, Krzysztof; Gauffre, Stéphane; Theron, Isak P.; Pantaleev, Miroslav; Ljusic, Zoran; Quertier, Benjamin; Peens-Hough, Adriaan

    2016-07-01

    The Square Kilometre Array (SKA) Project is a global science and engineering project realizing the next-generation radio telescopes operating in the metre and centimetre wavelengths regions. This paper addresses design concepts of the broadband, exceptionally sensitive receivers and reflector antennas deployed in the SKA1-Mid radio telescope to be located in South Africa. SKA1-Mid (350 MHz - 13.8 GHz with an option for an upper limit of 24 GHz) will consist of 133 reflector antennas using an unblocked aperture, offset Gregorian configuration with an effective diameter of 15 m. Details on the unblocked aperture Gregorian antennas, low noise front ends and advanced direct digitization receivers, are provided from a system design perspective. The unblocked aperture results in increased aperture efficiency and lower side-lobe levels compared to a traditional on-axis configuration. The low side-lobe level reduces the noise contribution due to ground pick-up but also makes the antenna less susceptible to ground-based RFI sources. The addition of extra shielding on the sub-reflector provides a further reduction of ground pick-up. The optical design of the SKA1-Mid reflector antenna has been tweaked using advanced EM simulation tools in combination with sophisticated models for sky, atmospheric and ground noise contributions. This optimal antenna design in combination with very low noise, partially cryogenic, receivers and wide instantaneous bandwidth provide excellent receiving sensitivity in combination with instrumental flexibility to accommodate a wide range of astronomical observation modes.

  10. Clusters of Galaxies and the Cosmic Web with Square Kilometre Array

    NASA Astrophysics Data System (ADS)

    Kale, Ruta; Dwarakanath, K. S.; Vir Lal, Dharam; Bagchi, Joydeep; Paul, Surajit; Malu, Siddharth; Datta, Abhirup; Parekh, Viral; Sharma, Prateek; Pandey-Pommier, Mamta

    2016-12-01

    The intra-cluster and inter-galactic media that pervade the large scale structure of the Universe are known to be magnetized at sub-micro Gauss to micro Gauss levels and to contain cosmic rays. The acceleration of cosmic rays and their evolution along with that of magnetic fields in these media is still not well understood. Diffuse radio sources of synchrotron origin associated with the Intra-Cluster Medium (ICM) such as radio halos, relics and mini-halos are direct probes of the underlying mechanisms of cosmic ray acceleration. Observations with radio telescopes such as the Giant Metrewave Radio Telescope, the Very Large Array and the Westerbork Synthesis Radio Telescope have led to the discoveries of about 80 such sources and allowed detailed studies in the frequency range 0.15-1.4 GHz of a few. These studies have revealed scaling relations between the thermal and non-thermal properties of clusters and favour the role of shocks in the formation of radio relics and of turbulent re-acceleration in the formation of radio halos and mini-halos. The radio halos are known to occur in merging clusters and mini-halos are detected in about half of the cool-core clusters. Due to the limitations of current radio telescopes, low mass galaxy clusters and galaxy groups remain unexplored as they are expected to contain much weaker radio sources. Distinguishing between the primary and the secondary models of cosmic ray acceleration mechanisms requires spectral measurements over a wide range of radio frequencies and with high sensitivity. Simulations have also predicted weak diffuse radio sources associated with filaments connecting galaxy clusters. The Square Kilometre Array (SKA) is a next generation radio telescope that will operate in the frequency range of 0.05-20 GHz with unprecedented sensitivities and resolutions. The expected detection limits of SKA will reveal a few hundred to thousand new radio halos, relics and mini-halos providing the first large and comprehensive

  11. The prospects of pulsar timing with new-generation radio telescopes and the Square Kilometre Array.

    PubMed

    Stappers, B W; Keane, E F; Kramer, M; Possenti, A; Stairs, I H

    2018-05-28

    Pulsars are highly magnetized and rapidly rotating neutron stars. As they spin, the lighthouse-like beam of radio emission from their magnetic poles sweeps across the Earth with a regularity approaching that of the most precise clocks known. This precision combined with the extreme environments in which they are found, often in compact orbits with other neutron stars and white dwarfs, makes them excellent tools for studying gravity. Present and near-future pulsar surveys, especially those using the new generation of telescopes, will find more extreme binary systems and pulsars that are more precise 'clocks'. These telescopes will also greatly improve the precision to which we can measure the arrival times of the pulses. The Square Kilometre Array will revolutionize pulsar searches and timing precision. The increased number of sources will reveal rare sources, including possibly a pulsar-black hole binary, which can provide the most stringent tests of strong-field gravity. The improved timing precision will reveal new phenomena and also allow us to make a detection of gravitational waves in the nanohertz frequency regime. It is here where we expect to see the signature of the binary black holes that are formed as galaxies merge throughout cosmological history.This article is part of a discussion meeting issue 'The promises of gravitational-wave astronomy'. © 2018 The Author(s).

  12. Automated detection of extended sources in radio maps: progress from the SCORPIO survey

    NASA Astrophysics Data System (ADS)

    Riggi, S.; Ingallinera, A.; Leto, P.; Cavallaro, F.; Bufano, F.; Schillirò, F.; Trigilio, C.; Umana, G.; Buemi, C. S.; Norris, R. P.

    2016-08-01

    Automated source extraction and parametrization represents a crucial challenge for the next-generation radio interferometer surveys, such as those performed with the Square Kilometre Array (SKA) and its precursors. In this paper, we present a new algorithm, called CAESAR (Compact And Extended Source Automated Recognition), to detect and parametrize extended sources in radio interferometric maps. It is based on a pre-filtering stage, allowing image denoising, compact source suppression and enhancement of diffuse emission, followed by an adaptive superpixel clustering stage for final source segmentation. A parametrization stage provides source flux information and a wide range of morphology estimators for post-processing analysis. We developed CAESAR in a modular software library, also including different methods for local background estimation and image filtering, along with alternative algorithms for both compact and diffuse source extraction. The method was applied to real radio continuum data collected at the Australian Telescope Compact Array (ATCA) within the SCORPIO project, a pathfinder of the Evolutionary Map of the Universe (EMU) survey at the Australian Square Kilometre Array Pathfinder (ASKAP). The source reconstruction capabilities were studied over different test fields in the presence of compact sources, imaging artefacts and diffuse emission from the Galactic plane and compared with existing algorithms. When compared to a human-driven analysis, the designed algorithm was found capable of detecting known target sources and regions of diffuse emission, outperforming alternative approaches over the considered fields.

  13. Active Galactic Nucleus Feedback with the Square Kilometre Array and Implications for Cluster Physics and Cosmology

    NASA Astrophysics Data System (ADS)

    Iqbal, Asif; Kale, Ruta; Majumdar, Subhabrata; Nath, Biman B.; Pandge, Mahadev; Sharma, Prateek; Malik, Manzoor A.; Raychaudhury, Somak

    2017-12-01

    Active Galactic Nuclei (AGN) feedback is regarded as an important non-gravitational process in galaxy clusters, providing useful constraints on large-scale structure formation. It modifies the structure and energetics of the intra-cluster medium (ICM) and hence its understanding is crucially needed in order to use clusters as high precision cosmological probes. In this context, particularly keeping in mind the upcoming high quality radio data expected from radio surveys like Square Kilometre Array (SKA) with its higher sensitivity, high spatial and spectral resolutions, we review our current understanding of AGN feedback, its cosmological implications and the impact that SKA can have in revolutionizing our understanding of AGN feedback in large-scale structures. Recent developments regarding the AGN outbursts and its possible contribution to excess entropy in the hot atmospheres of groups and clusters, its correlation with the feedback energy in ICM, quenching of cooling flows and the possible connection between cool core clusters and radio mini-halos, are discussed. We describe current major issues regarding modeling of AGN feedback and its impact on the surrounding medium. With regard to the future of AGN feedback studies, we examine the possible breakthroughs that can be expected from SKA observations. In the context of cluster cosmology, for example, we point out the importance of SKA observations for cluster mass calibration by noting that most of z>1 clusters discovered by eROSITA X-ray mission can be expected to be followed up through a 1000 hour SKA1-mid programme. Moreover, approximately 1000 radio mini halos and ˜ 2500 radio halos at z<0.6 can be potentially detected by SKA1 and SKA2 and used as tracers of galaxy clusters and determination of cluster selection function.

  14. A Virtual Sky with Extragalactic H I and CO Lines for the Square Kilometre Array and the Atacama Large Millimeter/Submillimeter Array

    NASA Astrophysics Data System (ADS)

    Obreschkow, D.; Klöckner, H.-R.; Heywood, I.; Levrier, F.; Rawlings, S.

    2009-10-01

    We present a sky simulation of the atomic H I-emission line and the first 10 12C16O rotational emission lines of molecular gas in galaxies beyond the Milky Way. The simulated sky field has a comoving diameter of 500 h -1 Mpc; hence, the actual field of view depends on the (user-defined) maximal redshift z max; e.g., for z max = 10, the field of view yields ~4 × 4 deg2. For all galaxies, we estimate the line fluxes, line profiles, and angular sizes of the H I and CO-emission lines. The galaxy sample is complete for galaxies with cold hydrogen masses above 108 M sun. This sky simulation builds on a semi-analytic model of the cosmic evolution of galaxies in a Λ cold dark matter (ΛCDM) cosmology. The evolving CDM distribution was adopted from the Millennium Simulation, an N-body CDM simulation in a cubic box with a side length of 500 h -1 Mpc. This side length limits the coherence scale of our sky simulation: it is long enough to allow the extraction of the baryon acoustic oscillations in the galaxy power spectrum, yet the position and amplitude of the first acoustic peak will be imperfectly defined. This sky simulation is a tangible aid to the design and operation of future telescopes, such as the Square Kilometre Array, Large Millimeter Telescope, and Atacama Large Millimeter/Submillimeter Array. The results presented in this paper have been restricted to a graphical representation of the simulated sky and fundamental dN/dz analyses for peak flux density limited and total flux limited surveys of H I and CO. A key prediction is that H I will be harder to detect at redshifts z gsim 2 than predicted by a no-evolution model. The future verification or falsification of this prediction will allow us to qualify the semi-analytic models. -SAX-Sky"

  15. OHANA, the Optical Hawaiian Array for Nanoradian Astronomy. Towards kilometric infrared arrays

    NASA Astrophysics Data System (ADS)

    Perrin, G.

    Optical/Infrared Interferometry has become a mature technique with more and more astrophysical results in the past years. For historical and technical reasons, the traditional field of investigation of interferometers is stellar physics. With the advent of large telescopes and adaptive optics, more resolving and more sensitive interferometers are within reach with the promise to widen the target list. In particular, extragalactic sources will benefit from this revolution. A prototype instrument, 'OHANA, is described here. 'OHANA uses single-mode fibers to turn the large telescopes of the Mauna Kea summit into a large near-infrared kilometric array.

  16. Characterizing the zenithal night sky brightness in large territories: how many samples per square kilometre are needed?

    NASA Astrophysics Data System (ADS)

    Bará, Salvador

    2018-01-01

    A recurring question arises when trying to characterize, by means of measurements or theoretical calculations, the zenithal night sky brightness throughout a large territory: how many samples per square kilometre are needed? The optimum sampling distance should allow reconstructing, with sufficient accuracy, the continuous zenithal brightness map across the whole region, whilst at the same time avoiding unnecessary and redundant oversampling. This paper attempts to provide some tentative answers to this issue, using two complementary tools: the luminance structure function and the Nyquist-Shannon spatial sampling theorem. The analysis of several regions of the world, based on the data from the New world atlas of artificial night sky brightness, suggests that, as a rule of thumb, about one measurement per square kilometre could be sufficient for determining the zenithal night sky brightness of artificial origin at any point in a region to within ±0.1 magV arcsec-2 (in the root-mean-square sense) of its true value in the Johnson-Cousins V band. The exact reconstruction of the zenithal night sky brightness maps from samples taken at the Nyquist rate seems to be considerably more demanding.

  17. H I debris in the IC 1459 galaxy group

    NASA Astrophysics Data System (ADS)

    Saponara, Juliana; Koribalski, Bärbel S.; Benaglia, Paula; Fernández López, Manuel

    2018-01-01

    We present H I synthesis imaging of the giant elliptical galaxy IC 1459 and its surroundings with the Australia Telescope Compact Array. Our search for extended H I emission revealed a large complex of H I clouds near IC 1459, likely to be the debris from tidal interactions with neighbouring galaxies. The total H I mass (∼109 M⊙) in the detected clouds spans 250 kpc from the north-east of the gas-rich spiral NGC 7418A to the south-east of IC 1459. The extent and mass of the H I debris, which shows rather irregular morphology and kinematics, are similar to those in other nearby groups. Together with H I clouds recently detected near two other IC 1459 group members, namely IC 5270 and NGC 7418, using phased-array feeds on the Australian Square Kilometre Array Pathfinder, the detected debris make up a significant fraction of the group's intergalactic medium.

  18. Pathfinder aircraft flight #1

    NASA Image and Video Library

    1996-11-19

    The Pathfinder research aircraft's solar cell arrays are prominently displayed as it touches down on the bed of Rogers Dry Lake at the Dryden Flight Research Center, Edwards, California, following a test flight. The solar arrays covered more than 75 percent of Pathfinder's upper wing surface, and provided electricity to power its six electric motors, flight controls, communications links and a host of scientific sensors.

  19. Using kites for 3-D mapping of gullies at decimetre-resolution over several square kilometres: a case study on the Kamech catchment, Tunisia

    NASA Astrophysics Data System (ADS)

    Feurer, Denis; Planchon, Olivier; Amine El Maaoui, Mohamed; Ben Slimane, Abir; Rached Boussema, Mohamed; Pierrot-Deseilligny, Marc; Raclot, Damien

    2018-06-01

    Monitoring agricultural areas threatened by soil erosion often requires decimetre topographic information over areas of several square kilometres. Airborne lidar and remotely piloted aircraft system (RPAS) imagery have the ability to provide repeated decimetre-resolution and -accuracy digital elevation models (DEMs) covering these extents, which is unrealistic with ground surveys. However, various factors hamper the dissemination of these technologies in a wide range of situations, including local regulations for RPAS and the cost for airborne laser systems and medium-format RPAS imagery. The goal of this study is to investigate the ability of low-tech kite aerial photography to obtain DEMs with decimetre resolution and accuracy that permit 3-D descriptions of active gullying in cultivated areas of several square kilometres. To this end, we developed and assessed a two-step workflow. First, we used both heuristic experimental approaches in field and numerical simulations to determine the conditions that make a photogrammetric flight possible and effective over several square kilometres with a kite and a consumer-grade camera. Second, we mapped and characterised the entire gully system of a test catchment in 3-D. We showed numerically and experimentally that using a thin and light line for the kite is key for a complete 3-D coverage over several square kilometres. We thus obtained a decimetre-resolution DEM covering 3.18 km2 with a mean error and standard deviation of the error of +7 and 22 cm respectively, hence achieving decimetre accuracy. With this data set, we showed that high-resolution topographic data permit both the detection and characterisation of an entire gully system with a high level of detail and an overall accuracy of 74 % compared to an independent field survey. Kite aerial photography with simple but appropriate equipment is hence an alternative tool that has been proven to be valuable for surveying gullies with sub-metric details in a square-kilometre

  20. Correspondence and Least Squares Analyses of Soil and Rock Compositions for the Viking Lander 1 and Pathfinder Sites

    NASA Technical Reports Server (NTRS)

    Larsen, K. W.; Arvidson, R. E.; Jolliff, B. L.; Clark, B. C.

    2000-01-01

    Correspondence and Least Squares Mixing Analysis techniques are applied to the chemical composition of Viking 1 soils and Pathfinder rocks and soils. Implications for the parent composition of local and global materials are discussed.

  1. Pathfinder-Plus on flight in Hawaii

    NASA Technical Reports Server (NTRS)

    1998-01-01

    above 50,000 feet. Major activities of Pathfinder Plus' Hawaiian flights included detection of forest nutrient status, forest regrowth after damage caused by Hurricane Iniki in 1992, sediment/algal concentrations in coastal waters, and assessment of coral reef health. Pathfinder science activities were coordinated by NASA's Ames Research Center, Mountain View, California, and included researchers from the University of Hawaii and the University of California. Pathfinder is part of NASA's Environmental Research Aircraft and Sensor Technology (ERAST) program managed by NASA's Dryden Flight Research Center, Edwards, California. Pathfinder and Pathfinder Plus were designed, built, and operated by AeroVironment, Inc., Monrovia, California. Pathfinder had a 98.4-foot wing span and weighed 560 pounds. Pathfinder Plus has a 121-foot wing span and weighs about 700 pounds. Pathfinder was powered by six electric motors while Pathfinder Plus has eight. Pathfinder's solar arrays produced approximately 8,000 watts of power while Pathfinder Plus' solar arrays produce about 12,500 watts of power. Both Pathfinder aircraft were built primarily of composites, plastic, and foam.

  2. Pathfinder-Plus on flight over Hawaii

    NASA Technical Reports Server (NTRS)

    1998-01-01

    ,000 feet and flying non-stop for at least 4 days above 50,000 feet. Major activities of Pathfinder Plus' Hawaiian flights included detection of forest nutrient status, forest regrowth after damage caused by Hurricane Iniki in 1992, sediment/algal concentrations in coastal waters, and assessment of coral reef health. Pathfinder science activities were coordinated by NASA's Ames Research Center, Mountain View, California, and included researchers from the University of Hawaii and the University of California. Pathfinder is part of NASA's Environmental Research Aircraft and Sensor Technology (ERAST) program managed by NASA's Dryden Flight Research Center, Edwards, California. Pathfinder and Pathfinder Plus were designed, built, and operated by AeroVironment, Inc., Monrovia, California. Pathfinder had a 98.4-foot wing span and weighed 560 pounds. Pathfinder Plus has a 121-foot wing span and weighs about 700 pounds. Pathfinder was powered by six electric motors while Pathfinder Plus has eight. Pathfinder's solar arrays produced approximately 8,000 watts of power while Pathfinder Plus' solar arrays produce about 12,500 watts of power. Both Pathfinder aircraft were built primarily of composites, plastic, and foam.

  3. Pathfinder-Plus on flight over Hawaii

    NASA Technical Reports Server (NTRS)

    1998-01-01

    ,000 feet. Major activities of Pathfinder Plus' Hawaiian flights included detection of forest nutrient status, forest regrowth after damage caused by Hurricane Iniki in 1992, sediment/algal concentrations in coastal waters, and assessment of coral reef health. Pathfinder science activities were coordinated by NASA's Ames Research Center, Mountain View, California, and included researchers from the University of Hawaii and the University of California. Pathfinder is part of NASA's Environmental Research Aircraft and Sensor Technology (ERAST) program managed by NASA's Dryden Flight Research Center, Edwards, California. Pathfinder and Pathfinder Plus were designed, built, and operated by AeroVironment, Inc., Monrovia, California. Pathfinder had a 98.4-foot wing span and weighed 560 pounds. Pathfinder Plus has a 121-foot wing span and weighs about 700 pounds. Pathfinder was powered by six electric motors while Pathfinder Plus has eight. Pathfinder's solar arrays produced approximately 8,000 watts of power while Pathfinder Plus' solar arrays produce about 12,500 watts of power. Both Pathfinder aircraft were built primarily of composites, plastic, and foam.

  4. MIGHTEE: The MeerKAT International GHz Tiered Extragalactic Exploration

    NASA Astrophysics Data System (ADS)

    Taylor, A. Russ; Jarvis, Matt

    2017-05-01

    The MeerKAT telescope is the precursor of the Square Kilometre Array mid-frequency dish array to be deployed later this decade on the African continent. MIGHTEE is one of the MeerKAT large survey projects designed to pathfind SKA key science in cosmology and galaxy evolution. Through a tiered radio continuum deep imaging project including several fields totaling 20 square degrees to microJy sensitivities and an ultra-deep image of a single 1 square degree field of view, MIGHTEE will explore dark matter and large scale structure, the evolution of galaxies, including AGN activity and star formation as a function of cosmic time and environment, the emergence and evolution of magnetic fields in galaxies, and the magnetic counter part to large scale structure of the universe.

  5. Big Data Challenges for Large Radio Arrays

    NASA Technical Reports Server (NTRS)

    Jones, Dayton L.; Wagstaff, Kiri; Thompson, David; D'Addario, Larry; Navarro, Robert; Mattmann, Chris; Majid, Walid; Lazio, Joseph; Preston, Robert; Rebbapragada, Umaa

    2012-01-01

    Future large radio astronomy arrays, particularly the Square Kilometre Array (SKA), will be able to generate data at rates far higher than can be analyzed or stored affordably with current practices. This is, by definition, a "big data" problem, and requires an end-to-end solution if future radio arrays are to reach their full scientific potential. Similar data processing, transport, storage, and management challenges face next-generation facilities in many other fields.

  6. Pathfinder-Plus on a flight in Hawaii

    NASA Technical Reports Server (NTRS)

    1998-01-01

    4 days above 50,000 feet. Major activities of Pathfinder Plus' Hawaiian flights included detection of forest nutrient status, forest regrowth after damage caused by Hurricane Iniki in 1992, sediment/algal concentrations in coastal waters, and assessment of coral reef health. Pathfinder science activities were coordinated by NASA's Ames Research Center, Mountain View, California, and included researchers from the University of Hawaii and the University of California. Pathfinder is part of NASA's Environmental Research Aircraft and Sensor Technology (ERAST) program managed by NASA's Dryden Flight Research Center, Edwards, California. Pathfinder and Pathfinder Plus were designed, built, and operated by AeroVironment, Inc., Monrovia, California. Pathfinder had a 98.4-foot wing span and weighed 560 pounds. Pathfinder Plus has a 121-foot wing span and weighs about 700 pounds. Pathfinder was powered by six electric motors while Pathfinder Plus has eight. Pathfinder's solar arrays produced approximately 8,000 watts of power while Pathfinder Plus' solar arrays produce about 12,500 watts of power. Both Pathfinder aircraft were built primarily of composites, plastic, and foam.

  7. Pathfinder-Plus on flight over Hawaiian Islands

    NASA Technical Reports Server (NTRS)

    1998-01-01

    days above 50,000 feet. Major activities of Pathfinder Plus' Hawaiian flights included detection of forest nutrient status, forest regrowth after damage caused by Hurricane Iniki in 1992, sediment/algal concentrations in coastal waters, and assessment of coral reef health. Pathfinder science activities were coordinated by NASA's Ames Research Center, Mountain View, California, and included researchers from the University of Hawaii and the University of California. Pathfinder is part of NASA's Environmental Research Aircraft and Sensor Technology (ERAST) program managed by NASA's Dryden Flight Research Center, Edwards, California. Pathfinder and Pathfinder Plus were designed, built, and operated by AeroVironment, Inc., Monrovia, California. Pathfinder had a 98.4-foot wing span and weighed 560 pounds. Pathfinder Plus has a 121-foot wing span and weighs about 700 pounds. Pathfinder was powered by six electric motors while Pathfinder Plus has eight. Pathfinder's solar arrays produced approximately 8,000 watts of power while Pathfinder Plus' solar arrays produce about 12,500 watts of power. Both Pathfinder aircraft were built primarily of composites, plastic, and foam.

  8. Pathfinder aircraft taking off - setting new solar powered altitude record

    NASA Technical Reports Server (NTRS)

    1995-01-01

    The Pathfinder solar-powered remotely piloted aircraft climbs to a record-setting altitude of 50,567 feet during a flight Sept. 11, 1995, at NASA's Dryden Flight Research Center, Edwards, California. The flight was part of the NASA ERAST (Environmental Research Aircraft and Sensor Technology) program. The Pathfinder was designed and built by AeroVironment Inc., Monrovia, California. Solar arrays cover nearly all of the upper wing surface and produce electricity to power the aircraft's six motors. Pathfinder was a lightweight, solar-powered, remotely piloted flying wing aircraft used to demonstrate the use of solar power for long-duration, high-altitude flight. Its name denotes its mission as the 'Pathfinder' or first in a series of solar-powered aircraft that will be able to remain airborne for weeks or months on scientific sampling and imaging missions. Solar arrays covered most of the upper wing surface of the Pathfinder aircraft. These arrays provided up to 8,000 watts of power at high noon on a clear summer day. That power fed the aircraft's six electric motors as well as its avionics, communications, and other electrical systems. Pathfinder also had a backup battery system that could provide power for two to five hours, allowing for limited-duration flight after dark. Pathfinder flew at airspeeds of only 15 to 20 mph. Pitch control was maintained by using tiny elevators on the trailing edge of the wing while turns and yaw control were accomplished by slowing down or speeding up the motors on the outboard sections of the wing. On September 11, 1995, Pathfinder set a new altitude record for solar-powered aircraft of 50,567 feet above Edwards Air Force Base, California, on a 12-hour flight. On July 7, 1997, it set another, unofficial record of 71,500 feet at the Pacific Missile Range Facility, Kauai, Hawaii. In 1998, Pathfinder was modified into the longer-winged Pathfinder Plus configuration. (See the Pathfinder Plus photos and project description.)

  9. Source finding in linear polarization for LOFAR, and SKA predecessor surveys, using Faraday moments

    NASA Astrophysics Data System (ADS)

    Farnes, J. S.; Heald, G.; Junklewitz, H.; Mulcahy, D. D.; Haverkorn, M.; Van Eck, C. L.; Riseley, C. J.; Brentjens, M.; Horellou, C.; Vacca, V.; Jones, D. I.; Horneffer, A.; Paladino, R.

    2018-03-01

    The optimal source-finding strategy for linear polarization data is an unsolved problem, with many inhibitive factors imposed by the technically challenging nature of polarization observations. Such an algorithm is essential for Square Kilometre Array (SKA) pathfinder surveys, such as the Multifrequency Snapshot Sky Survey with the LOw Frequency ARray (LOFAR), as data volumes are significant enough to prohibit manual inspection. We present a new strategy of `Faraday Moments' for source-finding in linear polarization with LOFAR, using the moments of the frequency-dependent full-Stokes data (i.e. the mean, standard deviation, skewness, and excess kurtosis). Through simulations of the sky, we find that moments can identify polarized sources with a high completeness: 98.5 per cent at a signal to noise of 5. While the method has low reliability, rotation measure (RM) synthesis can be applied per candidate source to filter out instrumental and spurious detections. This combined strategy will result in a complete and reliable catalogue of polarized sources that includes the full sensitivity of the observational bandwidth. We find that the technique can reduce the number of pixels on which RM Synthesis needs to be performed by a factor of ≈1 × 105 for source distributions anticipated with modern radio telescopes. Through tests on LOFAR data, we find that the technique works effectively in the presence of diffuse emission. Extensions of this method are directly applicable to other upcoming radio surveys such as the POlarization Sky Survey of the Universe's Magnetism with the Australia Square Kilometre Array Pathfinder, and the SKA itself.

  10. Pathfinder-Plus takes off on flight in Hawaii

    NASA Technical Reports Server (NTRS)

    1998-01-01

    above 50,000 feet. Major activities of Pathfinder Plus' Hawaiian flights included detection of forest nutrient status, forest regrowth after damage caused by Hurricane Iniki in 1992, sediment/algal concentrations in coastal waters, and assessment of coral reef health. Pathfinder science activities were coordinated by NASA's Ames Research Center, Mountain View, California, and included researchers from the University of Hawaii and the University of California. Pathfinder is part of NASA's Environmental Research Aircraft and Sensor Technology (ERAST) program managed by NASA's Dryden Flight Research Center, Edwards, California. Pathfinder and Pathfinder Plus were designed, built, and operated by AeroVironment, Inc., Monrovia, California. Pathfinder had a 98.4-foot wing span and weighed 560 pounds. Pathfinder Plus has a 121-foot wing span and weighs about 700 pounds. Pathfinder was powered by six electric motors while Pathfinder Plus has eight. Pathfinder's solar arrays produced approximately 8,000 watts of power while Pathfinder Plus' solar arrays produce about 12,500 watts of power. Both Pathfinder aircraft were built primarily of composites, plastic, and foam.

  11. Cellular logic array for computation of squares

    NASA Technical Reports Server (NTRS)

    Shamanna, M.; Whitaker, S.; Canaris, J.

    1991-01-01

    A cellular logic array is described for squaring binary numbers. This array offers a significant increase in speed, with a relatively small hardware overhead. This improvement is a result of novel implementation of the formula (x + y)exp 2 = x(exp 2) + y(exp 2) + 2(x)(y). These results can also be incorporated in the existing arrays achieving considerable hardware reduction.

  12. Holographic beam mapping of the CHIME pathfinder array

    NASA Astrophysics Data System (ADS)

    Berger, Philippe; Newburgh, Laura B.; Amiri, Mandana; Bandura, Kevin; Cliche, Jean-François; Connor, Liam; Deng, Meiling; Denman, Nolan; Dobbs, Matt; Fandino, Mateus; Gilbert, Adam J.; Good, Deborah; Halpern, Mark; Hanna, David; Hincks, Adam D.; Hinshaw, Gary; Höfer, Carolin; Johnson, Andre M.; Landecker, Tom L.; Masui, Kiyoshi W.; Mena Parra, Juan; Oppermann, Niels; Pen, Ue-Li; Peterson, Jeffrey B.; Recnik, Andre; Robishaw, Timothy; Shaw, J. Richard; Siegel, Seth; Sigurdson, Kris; Smith, Kendrick; Storer, Emilie; Tretyakov, Ian; Van Gassen, Kwinten; Vanderlinde, Keith; Wiebe, Donald

    2016-08-01

    The Canadian Hydrogen Intensity Mapping Experiment (CHIME) Pathfinder radio telescope is currently surveying the northern hemisphere between 400 and 800 MHz. By mapping the large scale structure of neutral hydrogen through its redshifted 21 cm line emission between z 0.8-2.5 CHIME will contribute to our understanding of Dark Energy. Bright astrophysical foregrounds must be separated from the neutral hydrogen signal, a task which requires precise characterization of the polarized telescope beams. Using the DRAO John A. Galt 26 m telescope, we have developed a holography instrument and technique for mapping the CHIME Pathfinder beams. We report the status of the instrument and initial results of this effort.

  13. Pathfinder aircraft taking off - setting new solar powered altitude record

    NASA Technical Reports Server (NTRS)

    1995-01-01

    The Pathfinder solar-powered remotely piloted aircraft climbs to a record-setting altitude of 50,567 feet during a flight Sept. 11, 1995, at NASA's Dryden Flight Research Center, Edwards, California. Pathfinder was a lightweight, solar-powered, remotely piloted flying wing aircraft used to demonstrate the use of solar power for long-duration, high-altitude flight. Its name denotes its mission as the 'Pathfinder' or first in a series of solar-powered aircraft that will be able to remain airborne for weeks or months on scientific sampling and imaging missions. Solar arrays covered most of the upper wing surface of the Pathfinder aircraft. These arrays provided up to 8,000 watts of power at high noon on a clear summer day. That power fed the aircraft's six electric motors as well as its avionics, communications, and other electrical systems. Pathfinder also had a backup battery system that could provide power for two to five hours, allowing for limited-duration flight after dark. Pathfinder flew at airspeeds of only 15 to 20 mph. Pitch control was maintained by using tiny elevators on the trailing edge of the wing while turns and yaw control were accomplished by slowing down or speeding up the motors on the outboard sections of the wing. On September 11, 1995, Pathfinder set a new altitude record for solar-powered aircraft of 50,567 feet above Edwards Air Force Base, California, on a 12-hour flight. On July 7, 1997, it set another, unofficial record of 71,500 feet at the Pacific Missile Range Facility, Kauai, Hawaii. In 1998, Pathfinder was modified into the longer-winged Pathfinder Plus configuration. (See the Pathfinder Plus photos and project description.)

  14. Pathfinder-Plus on flight over Hawaiian island N'ihau

    NASA Technical Reports Server (NTRS)

    1998-01-01

    -stop for at least 4 days above 50,000 feet. Major activities of Pathfinder Plus' Hawaiian flights included detection of forest nutrient status, forest regrowth after damage caused by Hurricane Iniki in 1992, sediment/algal concentrations in coastal waters, and assessment of coral reef health. Pathfinder science activities were coordinated by NASA's Ames Research Center, Mountain View, California, and included researchers from the University of Hawaii and the University of California. Pathfinder is part of NASA's Environmental Research Aircraft and Sensor Technology (ERAST) program managed by NASA's Dryden Flight Research Center, Edwards, California. Pathfinder and Pathfinder Plus were designed, built, and operated by AeroVironment, Inc., Monrovia, California. Pathfinder had a 98.4-foot wing span and weighed 560 pounds. Pathfinder Plus has a 121-foot wing span and weighs about 700 pounds. Pathfinder was powered by six electric motors while Pathfinder Plus has eight. Pathfinder's solar arrays produced approximately 8,000 watts of power while Pathfinder Plus' solar arrays produce about 12,500 watts of power. Both Pathfinder aircraft were built primarily of composites, plastic, and foam.

  15. Pathfinder-Plus on flight near Hawaiian island N'ihau

    NASA Technical Reports Server (NTRS)

    1998-01-01

    flying non-stop for at least 4 days above 50,000 feet. Major activities of Pathfinder Plus' Hawaiian flights included detection of forest nutrient status, forest regrowth after damage caused by Hurricane Iniki in 1992, sediment/algal concentrations in coastal waters, and assessment of coral reef health. Pathfinder science activities were coordinated by NASA's Ames Research Center, Mountain View, California, and included researchers from the University of Hawaii and the University of California. Pathfinder is part of NASA's Environmental Research Aircraft and Sensor Technology (ERAST) program managed by NASA's Dryden Flight Research Center, Edwards, California. Pathfinder and Pathfinder Plus were designed, built, and operated by AeroVironment, Inc., Monrovia, California. Pathfinder had a 98.4-foot wing span and weighed 560 pounds. Pathfinder Plus has a 121-foot wing span and weighs about 700 pounds. Pathfinder was powered by six electric motors while Pathfinder Plus has eight. Pathfinder's solar arrays produced approximately 8,000 watts of power while Pathfinder Plus' solar arrays produce about 12,500 watts of power. Both Pathfinder aircraft were built primarily of composites, plastic, and foam.

  16. The Engineering Development Array: A Low Frequency Radio Telescope Utilising SKA Precursor Technology

    NASA Astrophysics Data System (ADS)

    Wayth, Randall; Sokolowski, Marcin; Booler, Tom; Crosse, Brian; Emrich, David; Grootjans, Robert; Hall, Peter J.; Horsley, Luke; Juswardy, Budi; Kenney, David; Steele, Kim; Sutinjo, Adrian; Tingay, Steven J.; Ung, Daniel; Walker, Mia; Williams, Andrew; Beardsley, A.; Franzen, T. M. O.; Johnston-Hollitt, M.; Kaplan, D. L.; Morales, M. F.; Pallot, D.; Trott, C. M.; Wu, C.

    2017-08-01

    We describe the design and performance of the Engineering Development Array, which is a low-frequency radio telescope comprising 256 dual-polarisation dipole antennas working as a phased array. The Engineering Development Array was conceived of, developed, and deployed in just 18 months via re-use of Square Kilometre Array precursor technology and expertise, specifically from the Murchison Widefield Array radio telescope. Using drift scans and a model for the sky brightness temperature at low frequencies, we have derived the Engineering Development Array's receiver temperature as a function of frequency. The Engineering Development Array is shown to be sky-noise limited over most of the frequency range measured between 60 and 240 MHz. By using the Engineering Development Array in interferometric mode with the Murchison Widefield Array, we used calibrated visibilities to measure the absolute sensitivity of the array. The measured array sensitivity matches very well with a model based on the array layout and measured receiver temperature. The results demonstrate the practicality and feasibility of using Murchison Widefield Array-style precursor technology for Square Kilometre Array-scale stations. The modular architecture of the Engineering Development Array allows upgrades to the array to be rolled out in a staged approach. Future improvements to the Engineering Development Array include replacing the second stage beamformer with a fully digital system, and to transition to using RF-over-fibre for the signal output from first stage beamformers.

  17. Astronomical Verification of a Stabilized Frequency Reference Transfer System for the Square Kilometer Array

    NASA Astrophysics Data System (ADS)

    Gozzard, David R.; Schediwy, Sascha W.; Dodson, Richard; Rioja, María J.; Hill, Mike; Lennon, Brett; McFee, Jock; Mirtschin, Peter; Stevens, Jamie; Grainge, Keith

    2017-07-01

    In order to meet its cutting-edge scientific objectives, the Square Kilometre Array (SKA) telescope requires high-precision frequency references to be distributed to each of its antennas. The frequency references are distributed via fiber-optic links and must be actively stabilized to compensate for phase noise imposed on the signals by environmental perturbations on the links. SKA engineering requirements demand that any proposed frequency reference distribution system be proved in “astronomical verification” tests. We present results of the astronomical verification of a stabilized frequency reference transfer system proposed for SKA-mid. The dual-receiver architecture of the Australia Telescope Compact Array was exploited to subtract the phase noise of the sky signal from the data, allowing the phase noise of observations performed using a standard frequency reference, as well as the stabilized frequency reference transfer system transmitting over 77 km of fiber-optic cable, to be directly compared. Results are presented for the fractional frequency stability and phase drift of the stabilized frequency reference transfer system for celestial calibrator observations at 5 and 25 GHz. These observations plus additional laboratory results for the transferred signal stability over a 166 km metropolitan fiber-optic link are used to show that the stabilized transfer system under test exceeds all SKA phase-stability requirements within a broad range of observing conditions. Furthermore, we have shown that alternative reference dissemination systems that use multiple synthesizers to supply reference signals to sub-sections of an array may limit the imaging capability of the telescope.

  18. Pathfinder-Plus on a flight over Hawaiian island N'ihau

    NASA Technical Reports Server (NTRS)

    1998-01-01

    -stop for at least 4 days above 50,000 feet. Major activities of Pathfinder Plus' Hawaiian flights included detection of forest nutrient status, forest regrowth after damage caused by Hurricane Iniki in 1992, sediment/algal concentrations in coastal waters, and assessment of coral reef health. Pathfinder science activities were coordinated by NASA's Ames Research Center, Mountain View, California, and included researchers from the University of Hawaii and the University of California. Pathfinder is part of NASA's Environmental Research Aircraft and Sensor Technology (ERAST) program managed by NASA's Dryden Flight Research Center, Edwards, California. Pathfinder and Pathfinder Plus were designed, built, and operated by AeroVironment, Inc., Monrovia, California. Pathfinder had a 98.4-foot wing span and weighed 560 pounds. Pathfinder Plus has a 121-foot wing span and weighs about 700 pounds. Pathfinder was powered by six electric motors while Pathfinder Plus has eight. Pathfinder's solar arrays produced approximately 8,000 watts of power while Pathfinder Plus' solar arrays produce about 12,500 watts of power. Both Pathfinder aircraft were built primarily of composites, plastic, and foam.

  19. Comparison of photoemission characteristics between square and circular wire array GaAs photocathodes.

    PubMed

    Deng, Wenjuan; Peng, Xincun; Zou, Jijun; Wang, Weilu; Liu, Yun; Zhang, Tao; Zhang, Yijun; Zhang, Daoli

    2017-11-10

    Two types of negative electron affinity gallium arsenide (GaAs) wire array photocathodes were fabricated by reactive ion etching and inductively coupled plasma etching of bulk GaAs material. High density GaAs wire arrays with high periodicity and good morphology were verified using scanning electron microscopy, and photoluminescence spectra confirmed the wire arrays had good crystalline quality. Reflection spectra showed that circular GaAs wire arrays had superior light trapping compared with square ones. However, after Cs/O activation, the square GaAs wire array photocathodes showed enhanced spectral response. The integral sensitivity of the square wire array photocathodes was approximately 2.8 times that of the circular arrays.

  20. Identification of metabolic pathways using pathfinding approaches: a systematic review.

    PubMed

    Abd Algfoor, Zeyad; Shahrizal Sunar, Mohd; Abdullah, Afnizanfaizal; Kolivand, Hoshang

    2017-03-01

    Metabolic pathways have become increasingly available for various microorganisms. Such pathways have spurred the development of a wide array of computational tools, in particular, mathematical pathfinding approaches. This article can facilitate the understanding of computational analysis of metabolic pathways in genomics. Moreover, stoichiometric and pathfinding approaches in metabolic pathway analysis are discussed. Three major types of studies are elaborated: stoichiometric identification models, pathway-based graph analysis and pathfinding approaches in cellular metabolism. Furthermore, evaluation of the outcomes of the pathways with mathematical benchmarking metrics is provided. This review would lead to better comprehension of metabolism behaviors in living cells, in terms of computed pathfinding approaches. © The Author 2016. Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  1. Square and Rectangular Arrays from Directed Assembly of Sphere-forming Diblock Copolymers in Thin Films

    NASA Astrophysics Data System (ADS)

    Ji, Shengxiang; Nagpal, Umang; Liao, Wen; de Pablo, Juan; Nealey, Paul

    2010-03-01

    Patterns of square and rectangular arrays with nanoscale dimensions are scientifically and technologically important. Fabrication of square array patterns in thin films has been demonstrated by directed assembly of cylinder-forming diblock copolymers on chemically patterned substrates, supramolecular assembly of diblock copolymers, and self-assembly of triblock terpolymers. However, a macroscopic area of square array patterns with long-range order has not been achieved, and the fabrication of rectangular arrays has not been reported so far. Here we report a facile approach for fabricating patterns of square and rectangular arrays by directing the assembly of sphere-forming diblock copolymers on chemically patterned substrates. On stripe patterns, a square arrangement of half spheres, corresponding to the (100) plane of the body-centred cubic (BCC) lattice, formed on film surfaces. When the underlying pattern periods mismatched with the copolymer period, the square pattern could be stretched (up to ˜60%) or compressed (˜15%) to form rectangular arrays. Monte Carlo simulations have been further used to verify the experimental results and the 3-dimensional arrangements of spheres.

  2. LADUMA: Looking At the Distant Universe with the MeerKAT Array

    NASA Astrophysics Data System (ADS)

    Baker, Andrew J.; Blyth, Sarah; Holwerda, Benne W.; LADUMA team

    2018-01-01

    The cosmic evolution of galaxies' neutral atomic gas content is a major science driver for the Square Kilometre Array (SKA), as well as for its Australian (ASKAP) and South African (MeerKAT) precursors. Among the HI surveys planned for ASKAP and MeerKAT, the deepest and narrowest tier of the "wedding cake" will be defined by the approved 3424-hour Looking At the Distant Universe with the MeerKAT Array (LADUMA) survey, which will probe HI in emission within a single "cosmic vuvuzela" that extends to z = 1.4, when the universe was only a third of its present age. Through a combination of individual and stacked detections (the latter relying on extensive multiwavelength studies of the survey's target field), LADUMA will study the redshift evolution of the baryonic Tully-Fisher relation and the cosmic HI density, the variation of the HI mass function with redshift and environment, and the connection between HI content and the properties of galaxies' stars (mass, age, etc.). The survey will also build a sample of OH megamaser detections that can be used to trace the cosmic merger history. This talk will introduce the science potential of LADUMA and plans for its execution starting in 2018.

  3. Pathfinder aircraft taking off - setting new solar powered altitude record

    NASA Image and Video Library

    1995-09-11

    The Pathfinder solar-powered remotely piloted aircraft climbs to a record-setting altitude of 50,567 feet during a flight Sept. 11, 1995, at NASA's Dryden Flight Research Center, Edwards, California. The flight was part of the NASA ERAST (Environmental Research Aircraft and Sensor Technology) program. The Pathfinder was designed and built by AeroVironment Inc., Monrovia, California. Solar arrays cover nearly all of the upper wing surface and produce electricity to power the aircraft's six motors.

  4. Synchrotron Emission from Dark Matter Annihilation: Predictions for Constraints from Non-detections of Galaxy Clusters with New Radio Surveys

    NASA Astrophysics Data System (ADS)

    Storm, Emma; Jeltema, Tesla E.; Splettstoesser, Megan; Profumo, Stefano

    2017-04-01

    The annihilation of dark matter particles is expected to yield a broad radiation spectrum via the production of Standard Model particles in astrophysical environments. In particular, electrons and positrons from dark matter annihilation produce synchrotron radiation in the presence of magnetic fields. Galaxy clusters are the most massive collapsed structures in the universe, and are known to host ˜μG-scale magnetic fields. They are therefore ideal targets to search for, or to constrain the synchrotron signal from dark matter annihilation. In this work, we use the expected sensitivities of several planned surveys from the next generation of radio telescopes to predict the constraints on dark matter annihilation models which will be achieved in the case of non-detections of diffuse radio emission from galaxy clusters. Specifically, we consider the Tier 1 survey planned for the Low Frequency Array (LOFAR) at 120 MHz, the Evolutionary Map of the Universe (EMU) survey planned for the Australian Square Kilometre Array Pathfinder (ASKAP) at 1.4 GHz, and planned surveys for Aperture Tile in Focus (APERTIF) at 1.4 GHz. We find that, for massive clusters and dark matter masses ≲ 100 {GeV}, the predicted limits on the annihilation cross section would rule out vanilla thermal relic models for even the shallow LOFAR Tier 1, ASKAP, and APERTIF surveys.

  5. Pathfinder aircraft liftoff on altitude record setting flight of 71,500 feet

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The Pathfinder aircraft has set a new unofficial world record for high-altitude flight of over 71,500 feet for solar-powered aircraft at the U.S. Navy's Pacific Missile Range Facility, Kauai, Hawaii. Pathfinder was designed and manufactured by AeroVironment, Inc, of Simi Valley, California, and was operated by the firm under a jointly sponsored research agreement with NASA's Dryden Flight Research Center, Edwards, California. Pathfinder's record-breaking flight occurred July 7, 1997. The aircraft took off at 11:34 a.m. PDT, passed its previous record altitude of 67,350 feet at about 5:45 p.m. and then reached its new record altitude at 7 p.m. The mission ended with a perfect nighttime landing at 2:05 a.m. PDT July 8. The new record is the highest altitude ever attained by a propellor-driven aircraft. Before Pathfinder, the altitude record for propellor-driven aircraft was 67,028 feet, set by the experimental Boeing Condor remotely piloted aircraft. Pathfinder was a lightweight, solar-powered, remotely piloted flying wing aircraft used to demonstrate the use of solar power for long-duration, high-altitude flight. Its name denotes its mission as the 'Pathfinder' or first in a series of solar-powered aircraft that will be able to remain airborne for weeks or months on scientific sampling and imaging missions. Solar arrays covered most of the upper wing surface of the Pathfinder aircraft. These arrays provided up to 8,000 watts of power at high noon on a clear summer day. That power fed the aircraft's six electric motors as well as its avionics, communications, and other electrical systems. Pathfinder also had a backup battery system that could provide power for two to five hours, allowing for limited-duration flight after dark. Pathfinder flew at airspeeds of only 15 to 20 mph. Pitch control was maintained by using tiny elevators on the trailing edge of the wing while turns and yaw control were accomplished by slowing down or speeding up the motors on the outboard

  6. Astronomy in Australia

    NASA Astrophysics Data System (ADS)

    Watson, F.; Couch, W.

    2017-12-01

    Australians have watched the sky for tens of thousands of years. The nineteenth century saw the foundation of government observatories in capital cities such as Sydney and Melbourne. While early twentieth-century astronomy focused largely on solar physics, the advent of radio astronomy at the end of the Second World War enabled Australia to take a leading role in the new science, with particular emphasis on low-frequency studies. Today, the radio quietness of its outback interior provides an excellent location for the Australian core of the Square Kilometre Array. Australian optical astronomy has flourished since the 1960s, with the 3.9-metre Anglo-Australian Telescope becoming the principal national facility in 1974. Access to ESO’s facilities at the La Silla Paranal Observatory is warmly welcomed by all Australian astronomers.

  7. Pathfinder-Plus on flight over Hawaiian Islands, with N'ihau and Lehua in the background

    NASA Technical Reports Server (NTRS)

    1998-01-01

    and flying non-stop for at least 4 days above 50,000 feet. Major activities of Pathfinder Plus' Hawaiian flights included detection of forest nutrient status, forest regrowth after damage caused by Hurricane Iniki in 1992, sediment/algal concentrations in coastal waters, and assessment of coral reef health. Pathfinder science activities were coordinated by NASA's Ames Research Center, Mountain View, California, and included researchers from the University of Hawaii and the University of California. Pathfinder is part of NASA's Environmental Research Aircraft and Sensor Technology (ERAST) program managed by NASA's Dryden Flight Research Center, Edwards, California. Pathfinder and Pathfinder Plus were designed, built, and operated by AeroVironment, Inc., Monrovia, California. Pathfinder had a 98.4-foot wing span and weighed 560 pounds. Pathfinder Plus has a 121-foot wing span and weighs about 700 pounds. Pathfinder was powered by six electric motors while Pathfinder Plus has eight. Pathfinder's solar arrays produced approximately 8,000 watts of power while Pathfinder Plus' solar arrays produce about 12,500 watts of power. Both Pathfinder aircraft were built primarily of composites, plastic, and foam.

  8. Pathfinder ground preparations prior to altitude record setting flight of 71,500 feet

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Technicians make final adjustments on the solar-powered Pathfinder remotely piloted research aircraft prior to the craft's taking off on a flight which established a new unofficial world's altitude record for both propellor-driven and solar-powered aircraft. The new record of more than 71,500 feet was set during a 14 1/2-hour flight July 7, 1997, from the U.S. Navy's Pacific Missile Range Facility (PMRF) at Barking Sands, Kauai, Hawaii. The new altitude record is subject to verification by the National Aeronautics Association. The Pathfinder took off at 8:34 a.m. HDT, passed its previous record altitude of 67,350 feet about 2:45 p.m., and then reached its new mark at about 4 p.m. Controllers on the ground then initiated a slow decent, and Pathfinder landed seven hours later at 11:05 p.m. HDT. The experimental Boeing Condor remotely-piloted aircraft had held the previous record for propellor-driven craft of 67,028 feet. The Pathfinder had exceeded that height on a previous flight on June 9, 1997, but not by a large enough margin to be considered a new record. Pathfinder was a lightweight, solar-powered, remotely piloted flying wing aircraft used to demonstrate the use of solar power for long-duration, high-altitude flight. Its name denotes its mission as the 'Pathfinder' or first in a series of solar-powered aircraft that will be able to remain airborne for weeks or months on scientific sampling and imaging missions. Solar arrays covered most of the upper wing surface of the Pathfinder aircraft. These arrays provided up to 8,000 watts of power at high noon on a clear summer day. That power fed the aircraft's six electric motors as well as its avionics, communications, and other electrical systems. Pathfinder also had a backup battery system that could provide power for two to five hours, allowing for limited-duration flight after dark. Pathfinder flew at airspeeds of only 15 to 20 mph. Pitch control was maintained by using tiny elevators on the trailing edge of the

  9. Pathfinder in flight over Hawaii

    NASA Image and Video Library

    1997-08-28

    Pathfinder, NASA's solar-powered, remotely-piloted aircraft is shown while it was conducting a series of science flights to highlight the aircraft's science capabilities while collecting imagery of forest and coastal zone ecosystems on Kauai, Hawaii. The flights also tested two new scientific instruments, a high spectral resolution Digital Array Scanned Interferometer (DASI) and a high spatial resolution Airborne Real-Time Imaging System (ARTIS). The remote sensor payloads were designed by NASA's Ames Research Center, Moffett Field, California, to support NASA's Mission to Planet Earth science programs.

  10. Pathfinder over runway in Hawaii

    NASA Image and Video Library

    1997-08-28

    Pathfinder, NASA's solar-powered, remotely-piloted aircraft is shown while it was conducting a series of science flights to highlight the aircraft's science capabilities while collecting imagery of forest and coastal zone ecosystems on Kauai, Hawaii. The flights also tested two new scientific instruments, a high-spectral-resolution Digital Array Scanned Interferometer (DASI) and a high-spatial-resolution Airborne Real-Time Imaging System (ARTIS). The remote sensor payloads were designed by NASA's Ames Research Center, Moffett Field, California, to support NASA's Mission to Planet Earth science programs.

  11. Least-Squares Self-Calibration of Imaging Array Data

    NASA Technical Reports Server (NTRS)

    Arendt, R. G.; Moseley, S. H.; Fixsen, D. J.

    2004-01-01

    When arrays are used to collect multiple appropriately-dithered images of the same region of sky, the resulting data set can be calibrated using a least-squares minimization procedure that determines the optimal fit between the data and a model of that data. The model parameters include the desired sky intensities as well as instrument parameters such as pixel-to-pixel gains and offsets. The least-squares solution simultaneously provides the formal error estimates for the model parameters. With a suitable observing strategy, the need for separate calibration observations is reduced or eliminated. We show examples of this calibration technique applied to HST NICMOS observations of the Hubble Deep Fields and simulated SIRTF IRAC observations.

  12. Students' Spatial Structuring of 2D Arrays of Squares.

    ERIC Educational Resources Information Center

    Battista, Michael T.; Clements, Douglas H.; Arnoff, Judy; Battista, Kathryn; Van Auken Borrow, Caroline

    1998-01-01

    Defines spatial structuring as the mental operation of constructing an organization or form for an object/set of objects. Examines in detail students' structuring and enumeration of two-dimensional rectangular arrays of squares. Concludes that many students do not see row-by-column structure. Describes various levels of sophistication in students'…

  13. Polarization-independent absorption enhancement in a graphene square array with a cascaded grating structure.

    PubMed

    Wu, Jun

    2018-03-01

    The polarization-independent enhanced absorption effect of graphene in the near-infrared range is investigated. This is achieved by placing a graphene square array on top of a dielectric square array backed by a two-dimensional multilayer grating. Total optical absorption in graphene can be attributed to critical coupling, which is achieved through the combined effect of guided-mode resonance with the dielectric square array and the photonic band gap with the two-dimensional multilayer grating. To reveal the physical origin of such a phenomenon, the electromagnetic field distributions for both polarizations are illustrated. The designed graphene absorber exhibits near-unity polarization-independent absorption at resonance with an ultra-narrow spectrum. Moreover, the polarization-independent absorption can be tuned simply by changing the geometric parameters. The results may have promising potential for the design of graphene-based optoelectronic devices.

  14. Big data challenges for large radio arrays

    NASA Astrophysics Data System (ADS)

    Jones, D. L.; Wagstaff, K.; Thompson, D. R.; D'Addario, L.; Navarro, R.; Mattmann, C.; Majid, W.; Lazio, J.; Preston, J.; Rebbapragada, U.

    2012-03-01

    Future large radio astronomy arrays, particularly the Square Kilometre Array (SKA), will be able to generate data at rates far higher than can be analyzed or stored affordably with current practices. This is, by definition, a "big data" problem, and requires an end-to-end solution if future radio arrays are to reach their full scientific potential. Similar data processing, transport, storage, and management challenges face next-generation facilities in many other fields. The Jet Propulsion Laboratory is developing technologies to address big data issues, with an emphasis in three areas: 1) Lower-power digital processing architectures to make highvolume data generation operationally affordable, 2) Date-adaptive machine learning algorithms for real-time analysis (or "data triage") of large data volumes, and 3) Scalable data archive systems that allow efficient data mining and remote user code to run locally where the data are stored.

  15. Matched Field Processing Based on Least Squares with a Small Aperture Hydrophone Array.

    PubMed

    Wang, Qi; Wang, Yingmin; Zhu, Guolei

    2016-12-30

    The receiver hydrophone array is the signal front-end and plays an important role in matched field processing, which usually covers the whole water column from the sea surface to the bottom. Such a large aperture array is very difficult to realize. To solve this problem, an approach called matched field processing based on least squares with a small aperture hydrophone array is proposed, which decomposes the received acoustic fields into depth function matrix and amplitudes of the normal modes at the beginning. Then all the mode amplitudes are estimated using the least squares in the sense of minimum norm, and the amplitudes estimated are used to recalculate the received acoustic fields of the small aperture array, which means the recalculated ones contain more environmental information. In the end, lots of numerical experiments with three small aperture arrays are processed in the classical shallow water, and the performance of matched field passive localization is evaluated. The results show that the proposed method can make the recalculated fields contain more acoustic information of the source, and the performance of matched field passive localization with small aperture array is improved, so the proposed algorithm is proved to be effective.

  16. Matched Field Processing Based on Least Squares with a Small Aperture Hydrophone Array

    PubMed Central

    Wang, Qi; Wang, Yingmin; Zhu, Guolei

    2016-01-01

    The receiver hydrophone array is the signal front-end and plays an important role in matched field processing, which usually covers the whole water column from the sea surface to the bottom. Such a large aperture array is very difficult to realize. To solve this problem, an approach called matched field processing based on least squares with a small aperture hydrophone array is proposed, which decomposes the received acoustic fields into depth function matrix and amplitudes of the normal modes at the beginning. Then all the mode amplitudes are estimated using the least squares in the sense of minimum norm, and the amplitudes estimated are used to recalculate the received acoustic fields of the small aperture array, which means the recalculated ones contain more environmental information. In the end, lots of numerical experiments with three small aperture arrays are processed in the classical shallow water, and the performance of matched field passive localization is evaluated. The results show that the proposed method can make the recalculated fields contain more acoustic information of the source, and the performance of matched field passive localization with small aperture array is improved, so the proposed algorithm is proved to be effective. PMID:28042828

  17. Pulsars Probe the Low-Frequency Gravitational Sky: Pulsar Timing Arrays Basics and Recent Results

    NASA Astrophysics Data System (ADS)

    Tiburzi, Caterina

    2018-03-01

    Pulsar Timing Array experiments exploit the clock-like behaviour of an array of millisecond pulsars, with the goal of detecting low-frequency gravitational waves. Pulsar Timing Array experiments have been in operation over the last decade, led by groups in Europe, Australia, and North America. These experiments use the most sensitive radio telescopes in the world, extremely precise pulsar timing models and sophisticated detection algorithms to increase the sensitivity of Pulsar Timing Arrays. No detection of gravitational waves has been made to date with this technique, but Pulsar Timing Array upper limits already contributed to rule out some models of galaxy formation. Moreover, a new generation of radio telescopes, such as the Five hundred metre Aperture Spherical Telescope and, in particular, the Square Kilometre Array, will offer a significant improvement to the Pulsar Timing Array sensitivity. In this article, we review the basic concepts of Pulsar Timing Array experiments, and discuss the latest results from the established Pulsar Timing Array collaborations.

  18. The Stretched Lens Array SquareRigger (SLASR) for Space Power

    NASA Technical Reports Server (NTRS)

    Piszczor, Michael F.; O'Neill, Mark J.; Eskenazi, Michael I.; Brandhorst, Henry W.

    2006-01-01

    For the past three years, our team has been developing, refining, and maturing a unique solar array technology known as Stretched Lens Array SquareRigger (SLASR). SLASR offers an unprecedented portfolio of state-of-the-art performance metrics, including areal power density, specific power, stowed power density, high-voltage capability, radiation hardness, modularity, scalability, mass-producibility, and cost-effectiveness. SLASR is particularly well suited to high-power space missions, including solar electric propulsion (SEP) space tugs, major exploration missions to the Moon and Mars, and power-intensive military spacecraft. SLASR is also very well suited to high-radiation missions, since the cell shielding mass penalty is 85% less for the SLASR concentrator array than for one-sun planar arrays. The paper describes SLASR technology and presents significant results of developments to date in a number of key areas, from advances in the key components to full-scale array hardware fabrication and evaluation. A summary of SLASR s unprecedented performance metrics, both near-term and longer term, will be presented. Plans for future SLASR developments and near-term space applications will also be outlined.

  19. The Square Kilometre Array: a challenge for 2020 to which Spain can contribute in 2012

    NASA Astrophysics Data System (ADS)

    Verdes-Montenegro, L.; Dios Santander-Vela, J. D.

    2013-05-01

    The SKA, composed of several hundreds of three different types of antennas with separations up to 3.000 km, and up to 200 square degrees field of view, will be the largest, most sensitive radio telescope ever built. It will be able to provide fundamental answers in areas such as the dark era, when gas in galaxies was first turned into stars and the first black holes formed, star formation in nearby galaxies from stellar birth to death, faint extragalactic emission, magnetism in galaxies, extrasolar planets, or confrontation of Einstein predictions with pulsars and black hole observations. The technological challenges involved offer an unprecedented opportunity to collaborate in the development of hardware and software technologies. The energy requirements of the SKA provide an opportunity to accelerate technology development in scalable renewable energy generation, distribution, storage and demand monitoring and reduction. Data transport will reach over a hundred times the current global internet traffic data rates, delivering as much data as the full World Wide Web. Processing this data torrent in real time will require high-performance distributed computing as well as data storage and innovative retrieval technologies in the exascale. This way to do science, based on data-intensive interdisciplinary cooperation, is the base of the concept of e-Science, which necessarily includes outreach as an indissoluble part of the knowledge-based human progress. The scientific and technological challenges and opportunities that SKA can bring to the Spanish community will be described in this talk.

  20. Pathfinder Rear Ramp

    NASA Image and Video Library

    1997-07-06

    NASA's Mars Pathfinder's rear rover ramp can be seen successfully unfurled in this image, taken at the end of Sol 2 by the Imager for Mars Pathfinder (IMP). This ramp was later used for the deployment of the microrover Sojourner, which occurred at the end of Sol 2. Areas of a lander petal and deflated airbag are visible at left. The image helped Pathfinder scientists determine that the rear ramp was the one to use for rover deployment. At upper right is the rock dubbed "Barnacle Bill," which Sojourner will later study. http://photojournal.jpl.nasa.gov/catalog/PIA00627

  1. Canadian Hydrogen Intensity Mapping Experiment (CHIME) pathfinder

    NASA Astrophysics Data System (ADS)

    Bandura, Kevin; Addison, Graeme E.; Amiri, Mandana; Bond, J. Richard; Campbell-Wilson, Duncan; Connor, Liam; Cliche, Jean-François; Davis, Greg; Deng, Meiling; Denman, Nolan; Dobbs, Matt; Fandino, Mateus; Gibbs, Kenneth; Gilbert, Adam; Halpern, Mark; Hanna, David; Hincks, Adam D.; Hinshaw, Gary; Höfer, Carolin; Klages, Peter; Landecker, Tom L.; Masui, Kiyoshi; Mena Parra, Juan; Newburgh, Laura B.; Pen, Ue-li; Peterson, Jeffrey B.; Recnik, Andre; Shaw, J. Richard; Sigurdson, Kris; Sitwell, Mike; Smecher, Graeme; Smegal, Rick; Vanderlinde, Keith; Wiebe, Don

    2014-07-01

    A pathfinder version of CHIME (the Canadian Hydrogen Intensity Mapping Experiment) is currently being commissioned at the Dominion Radio Astrophysical Observatory (DRAO) in Penticton, BC. The instrument is a hybrid cylindrical interferometer designed to measure the large scale neutral hydrogen power spectrum across the redshift range 0.8 to 2.5. The power spectrum will be used to measure the baryon acoustic oscillation (BAO) scale across this poorly probed redshift range where dark energy becomes a significant contributor to the evolution of the Universe. The instrument revives the cylinder design in radio astronomy with a wide field survey as a primary goal. Modern low-noise amplifiers and digital processing remove the necessity for the analog beam forming that characterized previous designs. The Pathfinder consists of two cylinders 37m long by 20m wide oriented north-south for a total collecting area of 1,500 square meters. The cylinders are stationary with no moving parts, and form a transit instrument with an instantaneous field of view of ~100 degrees by 1-2 degrees. Each CHIME Pathfinder cylinder has a feedline with 64 dual polarization feeds placed every ~30 cm which Nyquist sample the north-south sky over much of the frequency band. The signals from each dual-polarization feed are independently amplified, filtered to 400-800 MHz, and directly sampled at 800 MSps using 8 bits. The correlator is an FX design, where the Fourier transform channelization is performed in FPGAs, which are interfaced to a set of GPUs that compute the correlation matrix. The CHIME Pathfinder is a 1/10th scale prototype version of CHIME and is designed to detect the BAO feature and constrain the distance-redshift relation. The lessons learned from its implementation will be used to inform and improve the final CHIME design.

  2. Results of the Imager for Mars Pathfinder windsock experiment

    USGS Publications Warehouse

    Sullivan, R.; Greeley, R.; Kraft, M.; Wilson, G.; Golombek, M.; Herkenhoff, K.; Murphy, J.; Smith, P.

    2000-01-01

    The Imager for Mars Pathfinder (IMP) windsock experiment measured wind speeds at three heights within 1.2 m of the Martian surface during Pathfinder landed operations. These wind data allowed direct measurement of near-surface wind profiles on Mars for the first time, including determination of aerodynamic roughness length and wind friction speeds. Winds were light during periods of windsock imaging, but data from the strongest breezes indicate aerodynamic roughness length of 3 cm at the landing site, with wind friction speeds reaching 1 m/s. Maximum wind friction speeds were about half of the threshold-of-motion friction speeds predicted for loose, fine-grained materials on smooth Martian terrain and about one third of the threshold-of-motion friction speeds predicted for the same size particles over terrain with aerodynamic roughness of 3 cm. Consistent with this, and suggesting that low wind speeds prevailed when the windsock array was not imaged and/or no particles were available for aeolian transport, no wind-related changes to the surface during mission operations have been recognized. The aerodynamic roughness length reported here implies that proposed deflation of fine particles around the landing site, or activation of duneforms seen by IMP and Sojourner, would require wind speeds >28 m/s at the Pathfinder top windsock height (or >31 m/s at the equivalent Viking wind sensor height of 1.6 m) and wind speeds >45 m/s above 10 m. These wind speeds would cause rock abrasion if a supply of durable particles were available for saltation. Previous analyses indicate that the Pathfinder landing site probably is rockier and rougher than many other plains units on Mars, so aerodynamic roughness length elsewhere probably is less than the 3-cm value reported for the Pathfinder site. Copyright 2000 by the American Geophysical Union.

  3. Storage and computationally efficient permutations of factorized covariance and square-root information arrays

    NASA Technical Reports Server (NTRS)

    Muellerschoen, R. J.

    1988-01-01

    A unified method to permute vector stored Upper triangular Diagonal factorized covariance and vector stored upper triangular Square Root Information arrays is presented. The method involves cyclic permutation of the rows and columns of the arrays and retriangularization with fast (slow) Givens rotations (reflections). Minimal computation is performed, and a one dimensional scratch array is required. To make the method efficient for large arrays on a virtual memory machine, computations are arranged so as to avoid expensive paging faults. This method is potentially important for processing large volumes of radio metric data in the Deep Space Network.

  4. Martian Surface & Pathfinder Airbags

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This image of the Martian surface was taken in the afternoon of Mars Pathfinder's first day on Mars. Taken by the Imager for Mars Pathfinder (IMP camera), the image shows a diversity of rocks strewn in the foreground. A hill is visible in the distance (the notch within the hill is an image artifact). Airbags are seen at the lower right.

    The IMP is a stereo imaging system with color capability provided by 24 selectable filters -- twelve filters per 'eye.' It stands 1.8 meters above the Martian surface, and has a resolution of two millimeters at a range of two meters.

    Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is an operating division of the California Institute of Technology (Caltech). The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.

  5. The Mars Pathfinder Mission

    NASA Astrophysics Data System (ADS)

    Golombek, M. P.

    1996-09-01

    The Mars Pathfinder mission is a Discovery class mission that will place a small lander and rover on the surface of Mars on July 4, 1997. The Pathfinder flight system is a single small lander, packaged within an aeroshell and back cover with a back-pack-style cruise stage. The vehicle will be launched, fly independently to Mars, and enter the atmosphere directly on approach behind the aeroshell. The vehicle is slowed by a parachute and 3 small solid rockets before landing on inflated airbags. Petals of a small tetrahedron shaped lander open up, to right the vehicle. The lander is solar powered with batteries and will operate on the surface for up to a year, downlinking data on a high-gain antenna. Pathfinder will be the first mission to use a rover, with 3 imagers and an alpha proton X-ray spectrometer, to characterize the rocks and soils in a landing area over hundreds of square meters on Mars, which will provide a calibration point or "ground truth" for orbital remote sensing observations. The rover (includes a series of technology experiments), the instruments (including a stereo multispectral surface imager on a pop up mast and an atmospheric structure instrument-surface meteorology package) and the telemetry system will allow investigations of: the surface morphology and geology at meter scale, the petrology and geochemistry of rocks and soils, the magnetic properties of dust, soil mechanics and properties, a variety of atmospheric investigations and the rotational and orbital dynamics of Mars. Landing downstream from the mouth of a giant catastrophic outflow channel, Ares Vallis, offers the potential of identifying and analyzing a wide variety of crustal materials, from the ancient heavily cratered terrain, intermediate-aged ridged plains and reworked channel deposits, thus allowing first-order scientific investigations of the early differentiation and evolution of the crust, the development of weathering products and early environments and conditions on Mars.

  6. Mars Pathfinder Status at Launch

    NASA Technical Reports Server (NTRS)

    Spear, A. J.; Freeman, Delma C., Jr.; Braun, Robert D.

    1996-01-01

    The Mars Pathfinder Flight System is in final test, assembly and launch preparations at the Kennedy Space Center in Florida. Launch is scheduled for 2 Dec. 1996. The Flight System development, in particular the Entry, Descent, and Landing (EDL) system, was a major team effort involving JPL, other NASA centers and industry. This paper provides a summary Mars Pathfinder description and status at launch. In addition, a section by NASA's Langley Research Center, a key EDL contributor, is provided on their support to Mars Pathfinder. This section is included as an example of the work performed by Pathfinder team members outside JPL.

  7. MESUR Pathfinder Science Investigations

    NASA Technical Reports Server (NTRS)

    Golombek, M.

    1993-01-01

    The MESUR (Mars Environmental Survey) Pathfinder mission is the first Discovery mission planned for launch in 1996. MESUR Pathfinder is designed as an engineering demonstration of the entry, descent and landing approach to be employed by the follow-on MESUR Network mission, which will land of order 10 small stations on the surface of Mars to investigate interior, atmospheric and surface properties. Pathfinder is a small Mars lander, equipped with a microrover to deploy instruments and explore the local landing site. Instruments selected for Pathfinder include a surface imager on a 1 m pop-up mast (stereo with spectral filters), an atmospheric structure instrument/surface meteorology package, and an alpha proton x-ray spectrometer. The microrover will carry the alpha proton x-ray spectrometer to a number of different rocks and surface materials and provide close-up imaging...

  8. Development of Very Long Baseline Interferometry (VLBI) techniques in New Zealand: Array simulation, image synthesis and analysis

    NASA Astrophysics Data System (ADS)

    Weston, S. D.

    2008-04-01

    results to provide a quantative comparison of the different array configurations modelled. Included in the process is the development of a new antenna array visibility program which was based on a Perl code script written by Prof Steven Tingay to plot antenna visibilities for the Australian Square Kilometre Array (SKA) proposal. This has been expanded and improved removing the hard coded fixed assumptions for the SKA configuration, providing a new useful and flexible program for the wider astronomical community. A prototype user interface using html/cgi/perl was developed for the process so that the underlying software packages can be served over the web to a user via an internet browser. This was used to demonstrate how easy it is to provide a friendlier interface compared to the existing cumbersome and difficult command line driven interfaces (although the command line can be retained for more experienced users).

  9. A class of least-squares filtering and identification algorithms with systolic array architectures

    NASA Technical Reports Server (NTRS)

    Kalson, Seth Z.; Yao, Kung

    1991-01-01

    A unified approach is presented for deriving a large class of new and previously known time- and order-recursive least-squares algorithms with systolic array architectures, suitable for high-throughput-rate and VLSI implementations of space-time filtering and system identification problems. The geometrical derivation given is unique in that no assumption is made concerning the rank of the sample data correlation matrix. This method utilizes and extends the concept of oblique projections, as used previously in the derivations of the least-squares lattice algorithms. Exponentially weighted least-squares criteria are considered for both sliding and growing memory.

  10. Experimental investigation of flow characteristics around four square-cylinder arrays at subcritical Reynolds numbers

    NASA Astrophysics Data System (ADS)

    Liu, Mingyue; Xiao, Longfei; Yang, Lijun

    2015-09-01

    The Deep Draft Semi-Submersible (DDS) concepts are known for their favourable vertical motion performance. However, the DDS may experience critical Vortex-Induced Motion (VIM) stemming from the fluctuating forces on the columns. In order to investigate the current-induced excitation forces of VIM, an experimental study of flow characteristics around four square-section cylinders in a square configuration is presented. A number of column spacing ratios and array attack angles were considered to investigate the parametric influences. The results comprise flow patterns, drag and lift forces, as well as Strouhal numbers. It is shown that both the drag and lift forces acting on the cylinders are slightly different between the various L/D values, and the fluctuating forces peak at L/D = 4.14. The lift force of downstream cylinders reaches its maximum at around α = 15°. Furthermore, the flow around circular-section-cylinder arrays is also discussed in comparison with that of square cylinders.

  11. Sub-Femto-g Free Fall for Space-Based Gravitational Wave Observatories: LISA Pathfinder Results

    NASA Technical Reports Server (NTRS)

    Armano, M.; Audley, H.; Auger, G.; Baird, J. T.; Bassan, M.; Binetruy, P.; Born, M.; Bortoluzzi, D.; Brandt, N.; Thorpe, J. I.

    2016-01-01

    We report the first results of the LISA Pathfinder in-flight experiment. The results demonstrate that two free-falling reference test masses, such as those needed for a space-based gravitational wave observatory like LISA, can be put in free fall with a relative acceleration noise with a square root of the power spectral density of 5.2 +/- 0.1 fm s(exp -2)/square root of Hz, or (0.54 +/- 0.01) x 10(exp -15) g/square root of Hz, with g the standard gravity, for frequencies between 0.7 and 20 mHz. This value is lower than the LISA Pathfinder requirement by more than a factor 5 and within a factor 1.25 of the requirement for the LISA mission, and is compatible with Brownian noise from viscous damping due to the residual gas surrounding the test masses. Above 60 mHz the acceleration noise is dominated by interferometer displacement readout noise at a level of (34.8 +/- 0.3) fm square root of Hz, about 2 orders of magnitude better than requirements. At f less than or equal to 0.5 mHz we observe a low-frequency tail that stays below 12 fm s(exp -2)/square root of Hz down to 0.1 mHz. This performance would allow for a space-based gravitational wave observatory with a sensitivity close to what was originally foreseen for LISA.

  12. LISA Pathfinder

    NASA Technical Reports Server (NTRS)

    Stebbins, Robin

    2008-01-01

    USA Pathfinder is a space mission dedicated to demonstrating technology for the Laser Interferometer Space Antenna (LISA). LISA is a joint ESA/NASA mission to detect low-frequency gravitational waves on the 0.0001 to 0.1 Hz frequency band. LISA is expected to observe 100's of merging massive black hole binaries out z-15, tens of thousands of close compact binary systems in the Milky Way, merging intermediate-mass black hole binaries, tens of stellar-mass black holes falling into supermassive black holes in galactic centers, and possibly other exotic sources. Several critical LISA technologies have not been demonstrated at the requisite level of performance. In spaceflight, and some fight hardware cannot be tested in a 1-g environment. Hence, the LISA Pathfinder mission is being implemented to demonstrate these critical LISA technologies in a relevant flight environment. LISA Pathfinder mimics one arm of the LISA constellation by shrinking the 5-million-kilometer armlength down to a few tens of centimeters. The experimental concept is to measure the relative separation between two test masses nominally following their own geodesics, and thereby determine the relative residual acceleration between them near 1 mHz, about a decade above the lowest frequency required by LISA. To implement such a concept, disturbances on the test masses must be kept very small by many design features, but chiefly by "drag-free" flight. A drag-free spacecraft follows a free-falling test mass which it encloses, but has no mechanical connection to. The spacecraft senses it's orientation and separation with respect to the proof mass, and its propulsion system is commanded to keep the spacecraft centered about the test mass. Thus, the spacecraft shields the test mass from most external influences, and minimizes the effect of force gradients arising from the spacecraft, and acting on the test mass. LISA Pathfinder will compare the geodesic of one test mass against that of the other. Only a

  13. Tracking and Navigation of Future NASA Spacecraft with the Square Kilometer Array

    NASA Astrophysics Data System (ADS)

    Resch, G. M.; Jones, D. L.; Connally, M. J.; Weinreb, S.; Preston, R. A.

    2001-12-01

    The international radio astronomy community is currently working on the design of an array of small radio antennas with a total collecting area of one square kilometer - more than a hundred times that of the largest existing (100-m) steerable antennas. An array of this size would provide obvious advantages for high data rate telemetry reception and for spacecraft navigation. Among these advantages are a two-orders-of-magnitude increase in sensitivity for telemetry downlink, flexible sub-arraying to track multiple spacecraft simultaneously, increased reliability through the use of large numbers of identical array elements, very accurate real-time angular spacecraft tracking, and a dramatic reduction in cost per unit area. NASA missions in many disciplines, including planetary science, would benefit from this increased ground-based tracking capability. The science return from planned missions could be increased, and opportunities for less expensive or completely new kinds of missions would be created.

  14. Analogue solution for electrical capacity of membrane covered square cylinders in square array at high concentration.

    PubMed

    Cole, K S

    1975-12-01

    Analytical solutions of Laplace equations have given the electrical characteristics of membranes and interiors of spherical, ellipsoidal, and cylindrical cells in suspensions and tissues from impedance measurements, but the underlying assumptions may be invalid above 50% volume concentrations. However, resistance measurements on several nonconducting, close-packing forms in two and three dimensions closely predicted volume concentrations up to 100% by equations derived from Maxwell and Rayleigh. Calculations of membrane capacities of cells in suspensions and tissues from extensions of theory, as developed by Fricke and by Cole, have been useful but of unknown validity at high concentrations. A resistor analogue has been used to solve the finite difference approximation to the Laplace equation for the resistance and capacity of a square array of square cylindrical cells with surface capacity. An 11 x 11 array of resistors, simulating a quarter of the unit structure, was separated into intra- and extra-cellular regions by rows of capacitors corresponding to surface membrane areas from 3 x 3 to 11 x 11 or 7.5% to 100%. The extended Rayleigh equation predicted the cell concentrations and membrane capacities to within a few percent from boundary resistance and capacity measurements at low frequencies. This single example suggests that analytical solutions for other, similar two- and three-dimensional problems may be approximated up to near 100% concentrations and that there may be analytical justifications for such analogue solutions of Laplace equations.

  15. Pathfinder aircraft flight #1

    NASA Image and Video Library

    1996-11-19

    The Pathfinder solar-powered research aircraft settles in for landing on the bed of Rogers Dry Lake at the Dryden Flight Research Center, Edwards, California, after a successful test flight Nov. 19, 1996. The ultra-light craft flew a racetrack pattern at low altitudes over the flight test area for two hours while project engineers checked out various systems and sensors on the uninhabited aircraft. The Pathfinder was controlled by two pilots, one in a mobile control unit which followed the craft, the other in a stationary control station. Pathfinder, developed by AeroVironment, Inc., is one of several designs being evaluated under NASA's Environmental Research Aircraft and Sensor Technology (ERAST) program.

  16. 2D Bayesian automated tilted-ring fitting of disc galaxies in large H I galaxy surveys: 2DBAT

    NASA Astrophysics Data System (ADS)

    Oh, Se-Heon; Staveley-Smith, Lister; Spekkens, Kristine; Kamphuis, Peter; Koribalski, Bärbel S.

    2018-01-01

    We present a novel algorithm based on a Bayesian method for 2D tilted-ring analysis of disc galaxy velocity fields. Compared to the conventional algorithms based on a chi-squared minimization procedure, this new Bayesian-based algorithm suffers less from local minima of the model parameters even with highly multimodal posterior distributions. Moreover, the Bayesian analysis, implemented via Markov Chain Monte Carlo sampling, only requires broad ranges of posterior distributions of the parameters, which makes the fitting procedure fully automated. This feature will be essential when performing kinematic analysis on the large number of resolved galaxies expected to be detected in neutral hydrogen (H I) surveys with the Square Kilometre Array and its pathfinders. The so-called 2D Bayesian Automated Tilted-ring fitter (2DBAT) implements Bayesian fits of 2D tilted-ring models in order to derive rotation curves of galaxies. We explore 2DBAT performance on (a) artificial H I data cubes built based on representative rotation curves of intermediate-mass and massive spiral galaxies, and (b) Australia Telescope Compact Array H I data from the Local Volume H I Survey. We find that 2DBAT works best for well-resolved galaxies with intermediate inclinations (20° < i < 70°), complementing 3D techniques better suited to modelling inclined galaxies.

  17. Transient Phenomena: Opportunities for New Discoveries

    NASA Technical Reports Server (NTRS)

    Lazio, T. Joseph W.

    2010-01-01

    Known classes of radio wavelength transients range from the nearby (stellar flares and radio pulsars) to the distant Universe (gamma-ray burst afterglows). Hypothesized classes of radio transients include analogs of known objects, such as extrasolar planets emitting Jovian-like radio bursts and giant-pulse emitting pulsars in other galaxies, to the exotic, such as prompt emission from gamma-ray bursts, evaporating black holes and transmitters from other civilizations. Time domain astronomy has been recognized internationally as a means of addressing key scientific questions in astronomy and physics, and pathfinders and Precursors to the Square Kilometre Array (SKA) are beginning to offer a combination of wider fields of view and more wavelength agility than has been possible in the past. These improvements will continue when the SKA itself becomes operational. I illustrate the range of transient phenomena and discuss how the detection and study of radio transients will improve immensely.

  18. Fabrication of long linear arrays of plastic optical fibers with squared ends for the use of code mark printing lithography

    NASA Astrophysics Data System (ADS)

    Horiuchi, Toshiyuki; Watanabe, Jun; Suzuki, Yuta; Iwasaki, Jun-ya

    2017-05-01

    Two dimensional code marks are often used for the production management. In particular, in the production lines of liquid-crystal-display panels and others, data on fabrication processes such as production number and process conditions are written on each substrate or device in detail, and they are used for quality managements. For this reason, lithography system specialized in code mark printing is developed. However, conventional systems using lamp projection exposure or laser scan exposure are very expensive. Therefore, development of a low-cost exposure system using light emitting diodes (LEDs) and optical fibers with squared ends arrayed in a matrix is strongly expected. In the past research, feasibility of such a new exposure system was demonstrated using a handmade system equipped with 100 LEDs with a central wavelength of 405 nm, a 10×10 matrix of optical fibers with 1 mm square ends, and a 10X projection lens. Based on these progresses, a new method for fabricating large-scale arrays of finer fibers with squared ends was developed in this paper. At most 40 plastic optical fibers were arranged in a linear gap of an arraying instrument, and simultaneously squared by heating them on a hotplate at 120°C for 7 min. Fiber sizes were homogeneous within 496+/-4 μm. In addition, average light leak was improved from 34.4 to 21.3% by adopting the new method in place of conventional one by one squaring method. Square matrix arrays necessary for printing code marks will be obtained by piling the newly fabricated linear arrays up.

  19. JWST Pathfinder Telescope Integration

    NASA Technical Reports Server (NTRS)

    Matthews, Gary W.; Kennard, Scott H.; Broccolo, Ronald T.; Ellis, James M.; Daly, Elizabeth A.; Hahn, Walter G.; Amon, John N.; Mt. Pleasant, Stephen M.; Texter, Scott; Atkinson, Charles B.; hide

    2015-01-01

    The James Webb Space Telescope (JWST) is a 6.5m, segmented, IR telescope that will explore the first light of the universe after the big bang. In 2014, a major risk reduction effort related to the Alignment, Integration, and Test (AI&T) of the segmented telescope was completed. The Pathfinder telescope includes two Primary Mirror Segment Assemblies (PMSA's) and the Secondary Mirror Assembly (SMA) onto a flight-like composite telescope backplane. This pathfinder allowed the JWST team to assess the alignment process and to better understand the various error sources that need to be accommodated in the flight build. The successful completion of the Pathfinder Telescope provides a final integration roadmap for the flight operations that will start in August 2015.

  20. Testing of the LISA pathfinder GRS

    NASA Astrophysics Data System (ADS)

    Antonucci, Federica; Cavalleri, Antonella; Ciani, Giacomo; Congedo, Giuseppe; Dolesi, Rita; de Marchi, Fabrizio; Ferraioli, Luigi; Hueller, Mauro; Nicolodi, Daniele; Tombolato, David; Vitale, Stefano; Wass, Peter J.; Weber, William J.

    The ESA/NASA mission,LISA (Laser Interferometric Space Antenna), will measure gravita-tional waves emitted by astronomical sources, galactic and extra-galactic, at frequencies 10-4 to 10-1 Hz. LISA is a 5-million-km arm-length interferometer whose mirrors are test masses which must be nominally free-falling to a level which does not exceed 3 · 10-15 ms-2 Hz -1/2 in acceleration. LISA Pathfinder is a technology demonstration mission which will show that the relative parasitic acceleration between two masses on one spacecraft can be lower than 3 · 10-14 ms-2 Hz -1/2 , at frequencies around 1 mHz -one order of magnitude larger than LISA's goal. At the core of the LISA Pathfinder experiment is the GRS (gravitational reference sensor), a capacitive sensor with mm gaps used to measure the position of the test mass and actuate its position in 6-degrees-of-freedom. Testing the purity of free-fall for LISA Pathfinder on-ground is achieved using a torsion pendulum which allows us to measure force disturbances at a level relevant to LISA Pathfinder. We will present the latest campaign of tests of the LISA Pathfinder GRS using the 4-test-mass torsion pendulum facility aimed at measuring force-noise sources (responsible for the parasitic acceleration) for LISA Pathfinder in its frequency band. Our GRS , is the LISA Pathfinder flight-model replica, and its testing is crucial in verifying the design and performance of the flight instrument and measuring many of the unwanted disturbances which can limit the performance of LISA and LISA pathfinder. The measurements concern the dependence of the force on the test mass position in the sensor and their electrostatic coupling, electrostatic fields due to surface-potential variations and thermal gradients.

  1. Martian Surface & Pathfinder Airbags

    NASA Image and Video Library

    1997-07-05

    This image of the Martian surface was taken in the afternoon of Mars Pathfinder's first day on Mars. Taken by the Imager for Mars Pathfinder (IMP camera), the image shows a diversity of rocks strewn in the foreground. A hill is visible in the distance (the notch within the hill is an image artifact). Airbags are seen at the lower right. http://photojournal.jpl.nasa.gov/catalog/PIA00612

  2. Mars Pathfinder Atmospheric Entry Navigation Operations

    NASA Technical Reports Server (NTRS)

    Braun, R. D.; Spencer, D. A.; Kallemeyn, P. H.; Vaughan, R. M.

    1997-01-01

    On July 4, 1997, after traveling close to 500 million km, the Pathfinder spacecraft successfully completed entry, descent, and landing, coming to rest on the surface of Mars just 27 km from its target point. In the present paper, the atmospheric entry and approach navigation activities required in support of this mission are discussed. In particular, the flight software parameter update and landing site prediction analyses performed by the Pathfinder operations navigation team are described. A suite of simulation tools developed during Pathfinder's design cycle, but extendible to Pathfinder operations, are also presented. Data regarding the accuracy of the primary parachute deployment algorithm is extracted from the Pathfinder flight data, demonstrating that this algorithm performed as predicted. The increased probability of mission success through the software parameter update process is discussed. This paper also demonstrates the importance of modeling atmospheric flight uncertainties in the estimation of an accurate landing site. With these atmospheric effects included, the final landed ellipse prediction differs from the post-flight determined landing site by less then 0.5 km in downtrack.

  3. MARS PATHFINDER CAMERA TEST IN SAEF-2

    NASA Technical Reports Server (NTRS)

    1996-01-01

    In the Spacecraft Assembly and Encapsulation Facility-2 (SAEF-2), workers from the Jet Propulsion Laboratory (JPL) are conducting a systems test of the imager for the Mars Pathfinder. Mounted on the Pathfinder lander, the imager (the white cylindrical element the worker is touching) is a specially designed camera featuring a stereo-imaging system with color capability provided by a set of selectable filters. It is mounted on an extendable mast that will pop up after the lander touches down on the Martian surface. The imager will transmit images of the terrain, allowing engineers back on Earth to survey the landing site before the Pathfinder rover is deployed to explore the area. The Mars Pathfinder is scheduled for launch aboard a Delta II expendable launch vehicle on Dec. 2. JPL manages the Pathfinder project for NASA.

  4. The Data Processor of the JEM-EUSO pathfinders

    NASA Astrophysics Data System (ADS)

    Scotti, V.; Osteria, G.

    2014-06-01

    JEM-EUSO is a wide-angle refractive UV telescope being proposed for attachment to the Japanese Experiment Module on ISS. The main goal of the mission is to study Extreme Energy Cosmic Rays. Two pathfinder mission are now in progress: EUSO-TA and EUSO-Balloon. The EUSO-TA project foresees the installation of a telescope prototype in the Telescope Array site. The aim of this project is to calibrate the telescope with the TA fluorescence detector. An initial run of one year starting from 2013 is foreseen. EUSO-Balloon is a pathfinder mission in which a prototype telescope will be mounted on a stratospheric balloon. The main aim of this mission is to perform a end-to-end test of all the key technologies and instrumentation of JEM-EUSO detectors and to prove the global detection chain. EUSO-Balloon will measure the UV background fundamental for the development of the simulations. EUSO-Balloon has the potential to detect Extensive Air Showers from above, paving the way for any future space-based EECR observatory. We will present the Data Processor of the pathfinders. The DP is the component of the Electronics System which performs data management and instrument control. The DP controls front-end electronics, performs 2nd level trigger filtering, tags events with arrival time and payload position through a GPS system, manages mass memory for data storage, measures live and dead time of the telescope, provides signals for time synchronization of the event, performs housekeeping monitor and handles interface to the telemetry system. We will describe the main components of the DP, the state-of-the-art and the results of the tests carried out.

  5. Generation of high-order Hermite-Gaussian modes in end-pumped solid-state lasers for square vortex array laser beam generation.

    PubMed

    Chu, Shu-Chun; Chen, Yun-Ting; Tsai, Ko-Fan; Otsuka, Kenju

    2012-03-26

    This study reports the first systematic approach to the excitation of all high-order Hermite-Gaussian modes (HGMs) in end-pumped solid-state lasers. This study uses a metal-wire-inserted laser resonator accompanied with the "off axis pumping" approach. This study presents numerical analysis of the excitation of HGMs in end-pumped solid-state lasers and experimentally generated HGM patterns. This study also experimentally demonstrates the generation of an square vortex array laser beams by passing specific high-order HGMs (HGn,n + 1 or HGn + 1,n modes) through a Dove prism-embedded unbalanced Mach-Zehnder interferometer [Optics Express 16, 19934-19949]. The resulting square vortex array laser beams with embedded vortexes aligned in a square array can be applied to multi-spot dark optical traps in the future.

  6. Navigation Flight Operations for Mars Pathfinder

    NASA Technical Reports Server (NTRS)

    Vaughan, Robin M.; Kallemeyn, Pieter H., Jr.; Spencer, David A.; Braun, Robert D.

    2004-01-01

    On July 4, 1997, Mars Pathfinder became the first spacecraft to land on the surface of Mars in 21 years. Pathfinder was launched on December 4, 1996 and spent seven months en route to the red planet. This report discusses the navigation flight experience for the Mars Pathfinder interplanetary cruise. In particular, orbit determination and maneuver design and execution results are presented. Special emphasis is given to the navigation role in the days and hours leading up to and including the Entry, Descent, and Landing (EDL) phase.

  7. Observations and Analyses of Heliospheric Faraday Rotation of a Coronal Mass Ejection (CME) Using the LOw Frequency ARray (LOFAR) and Space-Based Imaging Techniques

    NASA Astrophysics Data System (ADS)

    Bisi, Mario Mark; Jensen, Elizabeth; Sobey, Charlotte; Fallows, Richard; Jackson, Bernard; Barnes, David; Giunta, Alessandra; Hick, Paul; Eftekhari, Tarraneh; Yu, Hsiu-Shan; Odstrcil, Dusan; Tokumaru, Munetoshi; Wood, Brian

    2017-04-01

    Geomagnetic storms of the highest intensity are general driven by coronal mass ejections (CMEs) impacting the Earth's space environment. Their intensity is driven by the speed, density, and, most-importantly, their magnetic-field orientation and magnitude of the incoming solar plasma. The most-significant magnetic-field factor is the North-South component (Bz in Geocentric Solar Magnetic - GSM - coordinates). At present, there are no reliable prediction methods available for this magnetic-field component ahead of the in-situ monitors around the Sun-Earth L1 point. Observations of Faraday rotation (FR) can be used to attempt to determine average magnetic-field orientations in the inner heliosphere. Such a technique has already been well demonstrated through the corona, ionosphere, and also the interstellar medium. Measurements of the polarisation of astronomical (or spacecraft in superior conjunction) radio sources (beacons/radio frequency carriers) through the inner corona of the Sun to obtain the FR have been demonstrated but mostly at relatively-high radio frequencies. Here we show some initial results of true heliospheric FR using the Low Frequency Array (LOFAR) below 200 MHz to investigate the passage of a coronal mass ejection (CME) across the line of sight. LOFAR is a next-generation low-frequency radio interferometer, and a pathfinder to the Square Kilometre Array (SKA) - LOW telescope. We demonstrate preliminary heliospheric FR results through the analysis of observations of pulsar J1022+1001, which commenced on 13 August 2014 at 13:00UT and spanned over 150 minutes in duration. We also show initial comparisons to the FR results via various modelling techniques and additional context information to understand the structure of the inner heliosphere being detected. This observation could indeed pave the way to an experiment which might be implemented for space-weather purposes that will eventually lead to a near-global method for determining the magnetic

  8. Mars Pathfinder Landing Site Workshop

    NASA Technical Reports Server (NTRS)

    Golombek, Matthew (Editor)

    1994-01-01

    The Mars Pathfinder Project is an approved Discovery-class mission that will place a lander and rover on the surface of the Red Planet in July 1997. The Mars Pathfinder Landing Site Workshop was designed to allow the Mars scientific community to provide input as to where to land Pathfinder on Mars. The workshop was attended by over 60 people from around the United States and from Europe. Over 20 landing sites were proposed at the workshop, and the scientific questions and problems concerning each were addressed. The workshop and the discussion that occured during and afterward have significantly improved the ability to select a scientifically exciting but safe landing site on Mars.

  9. MARS PATHFINDER PYRO SYSTEMS SWITCHING ACTIVITY

    NASA Technical Reports Server (NTRS)

    1996-01-01

    The Mars Pathfinder lander is subjected to a electrical and functional tests of its pyrotechic petal deployer system by Jet Propulsion Laboratory (JPL) engineers and technicians in KSC's Spacecraft Assembly and Encapsulation Facility (SAEF-2). In the background is the Pathfinder cruise stage, which the lander will be mated to once its functional tests are complete. The lander will remain attached to this stage during its six-to-seven-month journey to Mars. When the lander touches down on the surface of Mars next year, the pyrotechnic system will deploy its three petals open like a flower and allow the Sojourner autonomous rover to explore the Martian surface. The Mars Pathfinder is scheduled for launch aboard a Delta II expendable launch vehicle on Dec. 2, the beginning of a 24-day launch period. JPL is managing the Mars Pathfinder project for NASA.

  10. Mars Pathfinder Landing Site and Surroundings

    NASA Technical Reports Server (NTRS)

    2007-01-01

    NASA's Mars Pathfinder landed on Mars on July 4, 1997, and continued operating until Sept. 27 of that year. The landing site is on an ancient flood plain of the Ares and Tiu outflow channels. The High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter took an image on Dec. 21, 2006, that provides unprecedented detail of the geology of the region and hardware on the surface.

    [figure removed for brevity, see original site] HiRISE Image This is the entire image. The crater at center bottom was unofficially named 'Big Crater' by the Pathfinder team. Its wall was visible from Pathfinder, located 3 kilometers (2 miles) to the north. The two bright features to the upper left of Big Crater are the 'Twin Peaks,' also observed by Pathfinder. The bright mound to the upper right of the Twin Peaks is 'North Knob,' seen in Pathfinder images as peaking over the horizon.

    At this scale there is no obvious geologic evidence of an ancient flood. Rather, impact craters dominate the scene, attesting to an old surface. The age is probably on the order of 1.8 billion to 3.5 billion years, when the Ares and Tiu floods are estimated to have occurred. Wind-formed linear ripples and dunes are seen throughout and are concentrated within craters. Sets of polygonal ridges of enigmatic origin are seen east of the Pathfinder lander. Rocks are visible over the entire image, with heavy concentrations near fresh-looking craters. Most of them are probably blocks tossed outward by crater-forming impacts.

    The complete image is centered at 19.1 degrees north latitude, 326.8 degrees east longitude. The range to the target site was 284.7 kilometers (177.9 miles). At this distance the image scale is 28.5 centimeters (11 inches) per pixel, so objects about 85 centimeters (33 inches) across are resolved. The image shown here has been map-projected to 25 centimeters (10 inches) per pixel. North is up. The image was taken at a local Mars time

  11. Pathfinder: A Retrospective

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.; Lyons, Valerie (Technical Monitor)

    2002-01-01

    Mars is one of the most interesting planets in the solar system, featuring enormous canyons, giant volcanoes, and indications that, early in its history, it might have had rivers and perhaps even oceans. Five years ago, in July of 1997, the Pathfinder mission landed on Mars, bringing with it the microwave-oven sized Sojourner rover to wander around on the surface and analyse rocks. Among the experiments on the mission was one designed to analyse dust deposition. Pathfinder is only the first of an armada of spacecraft which will examine Mars from the pole to the equator in the next decade, culminating with a mission to bring humans to Mars.

  12. Pathfinder-Plus flight in Hawaii

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Pathfinder-Plus flight in Hawaii June 2002 AeroVironment's Pathfinder-Plus solar-powered flying wing recently flew a three-flight demonstration of its ability to relay third-generation cell phone and video signals as well as provide Internet linkage. The two pods underneath the center section of the wing carried the advanced two-way telecom package, developed by Japanese telecommunications interests.

  13. Pathfinder aircraft in flight

    NASA Image and Video Library

    1995-07-27

    The Pathfinder research aircraft's wing structure was clearly defined as it soared under a clear blue sky during a test flight July 27, 1995, from Dryden Flight Research Center, Edwards, California. The center section and outer wing panels of the aircraft had ribs constructed of thin plastic foam, while the ribs in the inner wing panels are fabricated from lightweight composite material. Developed by AeroVironment, Inc., the Pathfinder was one of several unmanned aircraft being evaluated under NASA's Environmental Research Aircraft and Sensor Technology (ERAST) program.

  14. DISSECTING PHOTOMETRIC REDSHIFT FOR ACTIVE GALACTIC NUCLEUS USING XMM- AND CHANDRA-COSMOS SAMPLES

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

    Salvato, M.; Hasinger, G.; Ilbert, O.

    2011-12-01

    In this paper, we release accurate photometric redshifts for 1692 counterparts to Chandra sources in the central square degree of the Cosmic Evolution Survey (COSMOS) field. The availability of a large training set of spectroscopic redshifts that extends to faint magnitudes enabled photometric redshifts comparable to the highest quality results presently available for normal galaxies. We demonstrate that morphologically extended, faint X-ray sources without optical variability are more accurately described by a library of normal galaxies (corrected for emission lines) than by active galactic nucleus (AGN) dominated templates, even if these sources have AGN-like X-ray luminosities. Preselecting the library onmore » the bases of the source properties allowed us to reach an accuracy {sigma}{sub {Delta}z/(1+z{sub s{sub p{sub e{sub c)}}}}}{approx}0.015 with a fraction of outliers of 5.8% for the entire Chandra-COSMOS sample. In addition, we release revised photometric redshifts for the 1735 optical counterparts of the XMM-detected sources over the entire 2 deg{sup 2} of COSMOS. For 248 sources, our updated photometric redshift differs from the previous release by {Delta}z > 0.2. These changes are predominantly due to the inclusion of newly available deep H-band photometry (H{sub AB} = 24 mag). We illustrate once again the importance of a spectroscopic training sample and how an assumption about the nature of a source together, with the number and the depth of the available bands, influences the accuracy of the photometric redshifts determined for AGN. These considerations should be kept in mind when defining the observational strategies of upcoming large surveys targeting AGNs, such as eROSITA at X-ray energies and the Australian Square Kilometre Array Pathfinder Evolutionary Map of the Universe in the radio band.« less

  15. Ventifacts at the Pathfinder landing site

    USGS Publications Warehouse

    Bridges, N.T.; Greeley, R.; Haldemann, A.F.C.; Herkenhoff, K. E.; Kraft, M.; Parker, T.J.; Ward, A.W.

    1999-01-01

    About half of the rocks at the Mars Pathfinder Ares Vallis landing site appear to be ventifacts, rocks abraded by windborne particles. Comparable resolution images taken by the Imager for Mars Pathfinder (IMP) camera and the Viking landers show that ventifacts are more abundant at the Pathfinder site. The ventifacts occur in several forms, including rocks with faceted edges, finger-like projections, elongated pits, flutes, grooves, and possible rills. The trends of elongated pits, flutes, grooves, and rills cluster at ???280-330?? clockwise from north and generally dip 10-30?? away from their trend direction. These orientations are indicative of southeast to northwest winds and differ from the trend of wind tails at the landing site, the direction of local wind streaks, and predictions of the Global Circulation Model, all of which indicate northeast to southwest winds. The disparity between these data sets strongly suggests that local circulation patterns have changed since the abrasion of the ventifacted rocks. The greater number of ventifacts at the Pathfinder site compared to either of the Viking sites is most easily explained as being due to a larger supply of abrading particles, composed of either sand-sized grains or indurated dust aggregates, and higher surface roughness, which should increase the momentum of saltating grains. The Pathfinder ventifacts may have formed shortly after the deposition of outflow channel sediments nearly 2 Gry ago, when a large local supply of abrading particles should have been abundant and atmospheric conditions may have been more conducive to rock abrasion from saltating grains. Based on how ventifacts form on Earth, the several ventifact forms seen at the Pathfinder site and their presence on some rocks but not on others are probably due to local airflow conditions, original rock shape, exposure duration, rock movement, and to a lesser extent, rock lithology. The abundance of ventifacts at the Pathfinder site, together with

  16. Integrating Subject Pathfinders into Online Catalogs.

    ERIC Educational Resources Information Center

    Jarvis, William E.

    1985-01-01

    Discusses the integration of subject pathfinders into online public access catalogs (OPAC) through following features: within the OPAC, offline user guide manuals, remotely printed upon user request, or online as saved searches displayed in help screen format. Excerpts of a pathfinder display for biotechnology are presented. Four sources are…

  17. MOC's Highest Resolution View of Mars Pathfinder Landing Site

    NASA Technical Reports Server (NTRS)

    2000-01-01

    too small to be resolved in an image where each pixel acquired by the MOC covers a square of 1.5 meters (5 feet) to a side, given the contrast conditions on Mars and the MOC's ability to discriminate contrast. At this scale, Pathfinder is not much larger than two pixels, and the same is true of the lost Polar Lander.

    No evidence has been found in the January 2000 MOC image of the aft portion of Mars Pathfinder's aeroshell or its parachute, either. If the aeroshell is laying on its side, as interpreted from Mars Pathfinder's images, then it would be very difficult to see this from orbit. Because Pathfinder did not image the parachute, it is not known how it may be configured on the surface--it could be wrapped around the aeroshell or a boulder, for example.

    This effort to photograph the Mars Pathfinder lander demonstrates that it is extremely difficult to find a lander on the surface of Mars using the Mars Orbiter Camera aboard the MGS spacecraft. This analysis suggests that it is not very likely that the December 1999 Polar Lander will be found by MOC.

  18. Using low-frequency pulsar observations to study the 3-D structure of the Galactic magnetic field

    NASA Astrophysics Data System (ADS)

    Sobey, C.; LOFAR Collaboration; MWA Collaboration

    2018-05-01

    The Galactic magnetic field (GMF) plays a role in many astrophysical processes and is a significant foreground to cosmological signals, such as the Epoch of Reionization (EoR), but is not yet well understood. Dispersion and Faraday rotation measurements (DMs and RMs, respectively) towards a large number of pulsars provide an efficient method to probe the three-dimensional structure of the GMF. Low-frequency polarisation observations with large fractional bandwidth can be used to measure precise DMs and RMs. This is demonstrated by a catalogue of RMs (corrected for ionospheric Faraday rotation) from the Low Frequency Array (LOFAR), with a growing complementary catalogue in the southern hemisphere from the Murchison Widefield Array (MWA). These data further our knowledge of the three-dimensional GMF, particularly towards the Galactic halo. Recently constructed or upgraded pathfinder and precursor telescopes, such as LOFAR and the MWA, have reinvigorated low-frequency science and represent progress towards the construction of the Square Kilometre Array (SKA), which will make significant advancements in studies of astrophysical magnetic fields in the future. A key science driver for the SKA-Low is to study the EoR, for which pulsar and polarisation data can provide valuable insights in terms of Galactic foreground conditions.

  19. Automated cross-identifying radio to infrared surveys using the LRPY algorithm: a case study

    NASA Astrophysics Data System (ADS)

    Weston, S. D.; Seymour, N.; Gulyaev, S.; Norris, R. P.; Banfield, J.; Vaccari, M.; Hopkins, A. M.; Franzen, T. M. O.

    2018-02-01

    Cross-identifying complex radio sources with optical or infra red (IR) counterparts in surveys such as the Australia Telescope Large Area Survey (ATLAS) has traditionally been performed manually. However, with new surveys from the Australian Square Kilometre Array Pathfinder detecting many tens of millions of radio sources, such an approach is no longer feasible. This paper presents new software (LRPY - Likelihood Ratio in PYTHON) to automate the process of cross-identifying radio sources with catalogues at other wavelengths. LRPY implements the likelihood ratio (LR) technique with a modification to account for two galaxies contributing to a sole measured radio component. We demonstrate LRPY by applying it to ATLAS DR3 and a Spitzer-based multiwavelength fusion catalogue, identifying 3848 matched sources via our LR-based selection criteria. A subset of 1987 sources have flux density values for all IRAC bands which allow us to use criteria to distinguish between active galactic nuclei (AGNs) and star-forming galaxies (SFG). We find that 936 radio sources ( ≈ 47 per cent) meet both of the Lacy and Stern AGN selection criteria. Of the matched sources, 295 have spectroscopic redshifts and we examine the radio to IR flux ratio versus redshift, proposing an AGN selection criterion below the Elvis radio-loud AGN limit for this dataset. Taking the union of all three AGNs selection criteria we identify 956 as AGNs ( ≈ 48 per cent). From this dataset, we find a decreasing fraction of AGNs with lower radio flux densities consistent with other results in the literature.

  20. Least Squares Neural Network-Based Wireless E-Nose System Using an SnO₂ Sensor Array.

    PubMed

    Shahid, Areej; Choi, Jong-Hyeok; Rana, Abu Ul Hassan Sarwar; Kim, Hyun-Seok

    2018-05-06

    Over the last few decades, the development of the electronic nose (E-nose) for detection and quantification of dangerous and odorless gases, such as methane (CH₄) and carbon monoxide (CO), using an array of SnO₂ gas sensors has attracted considerable attention. This paper addresses sensor cross sensitivity by developing a classifier and estimator using an artificial neural network (ANN) and least squares regression (LSR), respectively. Initially, the ANN was implemented using a feedforward pattern recognition algorithm to learn the collective behavior of an array as the signature of a particular gas. In the second phase, the classified gas was quantified by minimizing the mean square error using LSR. The combined approach produced 98.7% recognition probability, with 95.5 and 94.4% estimated gas concentration accuracies for CH₄ and CO, respectively. The classifier and estimator parameters were deployed in a remote microcontroller for the actualization of a wireless E-nose system.

  1. Charitable Food Systems' Capacity to Address Food Insecurity: An Australian Capital City Audit.

    PubMed

    Pollard, Christina M; Mackintosh, Bruce; Campbell, Cathy; Kerr, Deborah; Begley, Andrea; Jancey, Jonine; Caraher, Martin; Berg, Joel; Booth, Sue

    2018-06-12

    Australian efforts to address food insecurity are delivered by a charitable food system (CFS) which fails to meet demand. The scope and nature of the CFS is unknown. This study audits the organisational capacity of the CFS within the 10.9 square kilometres of inner-city Perth, Western Australia. A desktop analysis of services and 12 face-to-face interviews with representatives from CFS organisations was conducted. All CFS organisations were not-for⁻profit and guided by humanitarian or faith-based values. The CFS comprised three indirect services (IS) sourcing, banking and/or distributing food to 15 direct services (DS) providing food to recipients. DS offered 30 different food services at 34 locations feeding over 5670 people/week via 16 models including mobile and seated meals, food parcels, supermarket vouchers, and food pantries. Volunteer to paid staff ratios were 33:1 (DS) and 19:1 (IS). System-wide, food was mainly donated and most funding was philanthropic. Only three organisations received government funds. No organisation had a nutrition policy. The organisational capacity of the CFS was precarious due to unreliable, insufficient and inappropriate financial, human and food resources and structures. System-wide reforms are needed to ensure adequate and appropriate food relief for Australians experiencing food insecurity.

  2. (abstract) Scaling Nominal Solar Cell Impedances for Array Design

    NASA Technical Reports Server (NTRS)

    Mueller, Robert L; Wallace, Matthew T.; Iles, Peter

    1994-01-01

    This paper discusses a task the objective of which is to characterize solar cell array AC impedance and develop scaling rules for impedance characterization of large arrays by testing single solar cells and small arrays. This effort is aimed at formulating a methodology for estimating the AC impedance of the Mars Pathfinder (MPF) cruise and lander solar arrays based upon testing single cells and small solar cell arrays and to create a basis for design of a single shunt limiter for MPF power control of flight solar arrays having very different inpedances.

  3. Pathfinder landing sites at candidate SNC impact ejection sites

    NASA Technical Reports Server (NTRS)

    Golombek, Matthew P.

    1994-01-01

    If Mars Pathfinder were able to land at a site on Mars from which the SNC meteorites were ejected by impact, the Pathfinder mission would essentially represent a very inexpensive sample return mission. Geologic units that contain four potential impact craters from which SNC meteorites could have been ejected from Mars are accessible to the Mars Pathfinder lander. Determining that SNC meteorites came from a particular spot on Mars raises the intriguing possibility of using Pathfinder as a sample return mission and providing a radiometric age for the considerably uncertain martian crater-age timescale. Pathfinder instruments are capable of determining if the rock type at the landing site is similar to that of one or more of the SNC meteorites, which would strengthen the hypothesis that the SNC meteorites did, in fact, come from Mars. Unfortunately, instrument observations from Pathfinder are probably not capable of determining if the geologic unit sampled by the lander is definitively the unit from which a SNC meteorite came from as opposed to Mars in general or perhaps a particular region on Mars. This abstract evaluates the possibility of landing at potential SNC ejection sites and the ability of Pathfinder to identify the landing site as the place from which an SNC meteorite came.

  4. Dynamic Pathfinders: Leveraging Your OPAC to Create Resource Guides

    ERIC Educational Resources Information Center

    Hunter, Ben

    2008-01-01

    Library pathfinders are a time-tested method of leading library users to important resources. However, paper-based pathfinders suffer from space limitations, and both paper-based and Web-based pathfinders require frequent updates to keep up with new library acquisitions. This article details a step-by-step method to create an online dynamic…

  5. WE-G-204-03: Photon-Counting Hexagonal Pixel Array CdTe Detector: Optimal Resampling to Square Pixels

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

    Shrestha, S; Vedantham, S; Karellas, A

    Purpose: Detectors with hexagonal pixels require resampling to square pixels for distortion-free display of acquired images. In this work, the presampling modulation transfer function (MTF) of a hexagonal pixel array photon-counting CdTe detector for region-of-interest fluoroscopy was measured and the optimal square pixel size for resampling was determined. Methods: A 0.65mm thick CdTe Schottky sensor capable of concurrently acquiring up to 3 energy-windowed images was operated in a single energy-window mode to include ≥10 KeV photons. The detector had hexagonal pixels with apothem of 30 microns resulting in pixel spacing of 60 and 51.96 microns along the two orthogonal directions.more » Images of a tungsten edge test device acquired under IEC RQA5 conditions were double Hough transformed to identify the edge and numerically differentiated. The presampling MTF was determined from the finely sampled line spread function that accounted for the hexagonal sampling. The optimal square pixel size was determined in two ways; the square pixel size for which the aperture function evaluated at the Nyquist frequencies along the two orthogonal directions matched that from the hexagonal pixel aperture functions, and the square pixel size for which the mean absolute difference between the square and hexagonal aperture functions was minimized over all frequencies up to the Nyquist limit. Results: Evaluation of the aperture functions over the entire frequency range resulted in square pixel size of 53 microns with less than 2% difference from the hexagonal pixel. Evaluation of the aperture functions at Nyquist frequencies alone resulted in 54 microns square pixels. For the photon-counting CdTe detector and after resampling to 53 microns square pixels using quadratic interpolation, the presampling MTF at Nyquist frequency of 9.434 cycles/mm along the two directions were 0.501 and 0.507. Conclusion: Hexagonal pixel array photon-counting CdTe detector after resampling to square

  6. Pathfinder Innovation Projects

    EPA Pesticide Factsheets

    The Pathfinder program supports high-risk, high-reward research ideas with funding and staff time. The goal is to feed a culture of innovation in the Agency and integrate innovative ideas in EPA research programs.

  7. Free-Flight Experiments in LISA Pathfinder

    NASA Technical Reports Server (NTRS)

    Thorpe, J. I.; Cutler, C. J.; Hewitson, M.; Jennrich, O.; Maghami, P.; Paczkowski, S.; Russano, G.; Vitale, S.; Weber, W. J.

    2014-01-01

    The LISA Pathfinder mission will demonstrate the technology of drag-free test masses for use as inertial references in future space-based gravitational wave detectors. To accomplish this, the Pathfinder spacecraft will perform drag-free flight about a test mass while measuring the acceleration of this primary test mass relative to a second reference test mass. Because the reference test mass is contained within the same spacecraft, it is necessary to apply forces on it to maintain its position and attitude relative to the spacecraft. These forces are a potential source of acceleration noise in the LISA Pathfinder system that are not present in the full LISA configuration. While LISA Pathfinder has been designed to meet it's primary mission requirements in the presence of this noise, recent estimates suggest that the on-orbit performance may be limited by this 'suspension noise'. The drift-mode or free-flight experiments provide an opportunity to mitigate this noise source and further characterize the underlying disturbances that are of interest to the designers of LISA-like instruments. This article provides a high-level overview of these experiments and the methods under development to analyze the resulting data.

  8. Heat transfer in laminar flow along circular rods in infinite square arrays

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

    Kim, J.H.; Li, W.H.

    1988-02-01

    The need to understand heat transfer characteristics over rods or tube bundles often arises in the design of compact heat exchangers and safety analysis of nuclear reactors. In particular, the fuel bundles of typical light water nuclear reactors are composed of a large number of circular rods arranged in square array pattern. The purpose of the present study is to analyze heat transfer characteristics of flow in such a multirod geometric configuration. The analysis given here will follow as closely as possible the method of Sparrow et al. who analyzed a similar problem for circular cylinders arranged in an equilateralmore » triangular array. The following major assumptions are made in the present analysis: (1) Flow is fully developed laminar flow paralleled to the axis of rods. (2) The axial profile of the surface heat flux to the fluid is uniform.(3) Thermodynamic properties are assumed constant.« less

  9. Characteristics of shock-associated fast-drift kilometric radio bursts

    NASA Technical Reports Server (NTRS)

    Macdowall, R. J.; Kundu, M. R.; Stone, R. G.

    1987-01-01

    The existence of a class of fast-drift, shock-associated (SA), kilometric radio bursts which occur at the time of metric type II emission and which are not entirely the kilometric continuation of metric type III bursts has been reported previously (Cane et al., 1981). In this paper unambiguous SA event criteria are established for the purpose of statistically comparing SA events with conventional kilometric type III bursts. Applying these criteria to all long-duration, fast-drift bursts observed by the ISEE-3 spacecraft during a 28-month interval, it is found that more than 70 percent of the events satisfying the criteria are associated with the radio signatures of coronal shocks. If a given event is associated with a metric type II or type IV burst, it is 13 times more likely to satisfy the SA criteria than an event associated only with metric type III activity.

  10. Software Aids Visualization Of Mars Pathfinder Mission

    NASA Technical Reports Server (NTRS)

    Weidner, Richard J.

    1996-01-01

    Report describes Simulator for Imager for Mars Pathfinder (SIMP) computer program. SIMP generates "virtual reality" display of view through video camera on Mars lander spacecraft of Mars Pathfinder mission, along with display of pertinent textual and graphical data, for use by scientific investigators in planning sequences of activities for mission.

  11. Polarized point sources in the LOFAR Two-meter Sky Survey: A preliminary catalog

    NASA Astrophysics Data System (ADS)

    Van Eck, C. L.; Haverkorn, M.; Alves, M. I. R.; Beck, R.; Best, P.; Carretti, E.; Chyży, K. T.; Farnes, J. S.; Ferrière, K.; Hardcastle, M. J.; Heald, G.; Horellou, C.; Iacobelli, M.; Jelić, V.; Mulcahy, D. D.; O'Sullivan, S. P.; Polderman, I. M.; Reich, W.; Riseley, C. J.; Röttgering, H.; Schnitzeler, D. H. F. M.; Shimwell, T. W.; Vacca, V.; Vink, J.; White, G. J.

    2018-06-01

    The polarization properties of radio sources at very low frequencies (<200 MHz) have not been widely measured, but the new generation of low-frequency radio telescopes, including the Low Frequency Array (LOFAR: a Square Kilometre Array Low pathfinder), now gives us the opportunity to investigate these properties. In this paper, we report on the preliminary development of a data reduction pipeline to carry out polarization processing and Faraday tomography for data from the LOFAR Two-meter Sky Survey (LOTSS) and present the results of this pipeline from the LOTSS preliminary data release region (10h45m-15h30m right ascension, 45°-57° declination, 570 square degrees). We have produced a catalog of 92 polarized radio sources at 150 MHz at 4.'3 resolution and 1 mJy rms sensitivity, which is the largest catalog of polarized sources at such low frequencies. We estimate a lower limit to the polarized source surface density at 150 MHz, with our resolution and sensitivity, of 1 source per 6.2 square degrees. We find that our Faraday depth measurements are in agreement with previous measurements and have significantly smaller errors. Most of our sources show significant depolarization compared to 1.4 GHz, but there is a small population of sources with low depolarization indicating that their polarized emission is highly localized in Faraday depth. We predict that an extension of this work to the full LOTSS data would detect at least 3400 polarized sources using the same methods, and probably considerably more with improved data processing.

  12. Square array photonic crystal fiber-based surface plasmon resonance refractive index sensor

    NASA Astrophysics Data System (ADS)

    Liu, Min; Yang, Xu; Zhao, Bingyue; Hou, Jingyun; Shum, Ping

    2017-12-01

    Based on surface plasmon resonance (SPR), a novel refractive index (RI) sensor comprising a square photonic crystal fiber (PCF) is proposed to realize the detection of the annular analyte. Instead of hexagon structure, four large air-holes in a square array are introduced to enhance the sensitivity by allowing two polarization directions of the core mode to be more sensitive. The gold is used as the only plasmonic material. The design purpose is to reduce the difficulty in gold deposition and enhance the RI sensitivity. The guiding properties and the effects of the parameters on the performance of the sensor are numerically investigated by the Finite Element Method (FEM). By optimizing the structure, the sensor can exhibit remarkable sensitivity up to 7250 nm/RIU and resolution of 1.0638 × 10-5 RIU with only one plasmonic material, which is very competitive compared with the other reported externally coated and single-layer coated PCF-based SPR (PCF-SPR) sensors, to our best knowledge.

  13. JWST Pathfinder Telescope Risk Reduction Cryo Test Program

    NASA Technical Reports Server (NTRS)

    Matthews, Gary W.; Scorse, Thomas R.; Spina, John A.; Noel, Darin M.; Havey, Keith A., Jr.; Huguet, Jesse A.; Whitman, Tony L.; Wells, Conrad; Walker, Chanda B.; Lunt, Sharon; hide

    2015-01-01

    In 2014, the Optical Ground Support Equipment was integrated into the large cryo vacuum chamber at Johnson Space Center (JSC) and an initial Chamber Commissioning Test was completed. This insured that the support equipment was ready for the three Pathfinder telescope cryo tests. The Pathfinder telescope which consists of two primary mirror segment assemblies and the secondary mirror was delivered to JSC in February 2015 in support of this critical risk reduction test program prior to the flight hardware. This paper will detail the Chamber Commissioning and first optical test of the JWST Pathfinder telescope.

  14. Morphologies and optical and electrical properties of InGaN/GaN micro-square array light-emitting diode chips.

    PubMed

    Han, Dan; Ma, Shufang; Jia, Zhigang; Liu, Peizhi; Jia, Wei; Shang, Lin; Zhai, Guangmei; Xu, Bingshe

    2018-04-10

    InGaN/GaN micro-square array light-emitting diode (LED) chips (micro-chips) have been prepared via the focused ion beam (FIB) etching technique, which can not only reduce ohmic contact degradation but also control the aspect ratio precisely in three-dimensional (3D) structure LED (3D-LED) device fabrication. The effects of FIB beam current and micro-square array depth on morphologies and optical and electrical properties of the micro-chips have been studied. Our results show that sidewall surface morphology and optical and electrical properties of the micro-chips degrade with increased beam current. After potassium hydroxide etching with different times, an optimal current-voltage and luminescence performance can be obtained. Combining the results of cathodoluminescence mappings and light output-current characteristics, the light extraction efficiency of the micro-chips is reduced as FIB etch depth increases. The mechanisms of micro-square depth on light extraction have been revealed by 3D finite difference time domain.

  15. Estimating Noise in the Hydrogen Epoch of Reionization Array

    NASA Astrophysics Data System (ADS)

    Englund Mathieu, Philip; HERA Team

    2017-01-01

    The Hydrogen Epoch of Reionization Array (HERA) is a radio telescope dedicated to observing large scale structure during and prior to the epoch of reionization. Once completed, HERA will have unprecedented sensitivity to the 21-cm signal from hydrogen reionization. This poster will present time- and frequency-subtraction methods and results from a preliminary analysis of the noise characteristics of the nineteen-element pathfinder array.

  16. Topographic Map of Pathfinder Landing Site

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Topographic map of the landing site, to a distance of 60 meters from the lander in the LSC coordinate system. The lander is shown schematically in the center; 2.5 meter radius circle (black) centered on the camera was not mapped. Gentle relief [root mean square (rms) elevation variation 0.5 m; rms a directional slope 4O] and organization of topography into northwest and northeast-trending ridges about 20 meters apart are apparent. Roughly 30% of the illustrated area is hidden from the camera behind these ridges. Contours (0.2 m interval) and color coding of elevations were generated from a digital terrain model, which was interpolated by kriging from approximately 700 measured points. Angular and parallax point coordinates were measured manually on a large (5 m length) anaglyphic uncontrolled mosaic and used to calculate Cartesian (LSC) coordinates. Errors in azimuth on the order of 10 are therefore likely; elevation errors were minimized by referencing elevations to the local horizon. The uncertainty in range measurements increases quadratically with range. Given a measurement error of 1/2 pixel, the expected precision in range is 0.3 meter at 10 meter range, and 10 meters at 60 meter range. Repeated measurements were made, compared, and edited for consistency to improve the range precision. Systematic errors undoubtedly remain and will be corrected in future maps compiled digitally from geometrically controlled images. Cartographic processing by U.S. Geological Survey.

    NOTE: original caption as published in Science Magazine

    Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology (Caltech).

  17. Medicina array demonstrator: calibration and radiation pattern characterization using a UAV-mounted radio-frequency source

    NASA Astrophysics Data System (ADS)

    Pupillo, G.; Naldi, G.; Bianchi, G.; Mattana, A.; Monari, J.; Perini, F.; Poloni, M.; Schiaffino, M.; Bolli, P.; Lingua, A.; Aicardi, I.; Bendea, H.; Maschio, P.; Piras, M.; Virone, G.; Paonessa, F.; Farooqui, Z.; Tibaldi, A.; Addamo, G.; Peverini, O. A.; Tascone, R.; Wijnholds, S. J.

    2015-06-01

    One of the most challenging aspects of the new-generation Low-Frequency Aperture Array (LFAA) radio telescopes is instrument calibration. The operational LOw-Frequency ARray (LOFAR) instrument and the future LFAA element of the Square Kilometre Array (SKA) require advanced calibration techniques to reach the expected outstanding performance. In this framework, a small array, called Medicina Array Demonstrator (MAD), has been designed and installed in Italy to provide a test bench for antenna characterization and calibration techniques based on a flying artificial test source. A radio-frequency tone is transmitted through a dipole antenna mounted on a micro Unmanned Aerial Vehicle (UAV) (hexacopter) and received by each element of the array. A modern digital FPGA-based back-end is responsible for both data-acquisition and data-reduction. A simple amplitude and phase equalization algorithm is exploited for array calibration owing to the high stability and accuracy of the developed artificial test source. Both the measured embedded element patterns and calibrated array patterns are found to be in good agreement with the simulated data. The successful measurement campaign has demonstrated that a UAV-mounted test source provides a means to accurately validate and calibrate the full-polarized response of an antenna/array in operating conditions, including consequently effects like mutual coupling between the array elements and contribution of the environment to the antenna patterns. A similar system can therefore find a future application in the SKA-LFAA context.

  18. Pathfinder aircraft flight #1

    NASA Image and Video Library

    1996-11-19

    The Pathfinder solar-powered research aircraft is silhouetted against a clear blue sky as it soars aloft during a checkout flight from the Dryden Flight Research Center, Edwards, California, November, 1996.

  19. Solar array model corrections from Mars Pathfinder lander data

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

    Ewell, R.C.; Burger, D.R.

    1997-12-31

    The MESUR solar array power model initially assumed values for input variables. After landing early surface variables such as array tilt and azimuth or early environmental variables such as array temperature can be corrected. Correction of later environmental variables such as tau versus time, spectral shift, dust deposition, and UV darkening is dependent upon time, on-board science instruments, and ability to separate effects of variables. Engineering estimates had to be made for additional shadow losses and Voc sensor temperature corrections. Some variations had not been expected such as tau versus time of day, and spectral shift versus time of day.more » Additions needed to the model are thermal mass of lander petal and correction between Voc sensor and temperature sensor. Conclusions are: the model works well; good battery predictions are difficult; inclusion of Isc and Voc sensors was valuable; and the IMP and MAE science experiments greatly assisted the data analysis and model correction.« less

  20. Pathfinder

    NASA Image and Video Library

    2004-04-15

    This artist's concept depicts the X-34 Demonstrator in flight. Part of the Pathfinder Program, the X-34 was a reusable technology testbed vehicle that was designed and built by the Marshall Space Flight Center to demonstrate technologies that were essential to lowering the cost of access to space. Powered by a LOX and RP-1 liquid Fastrac engine, the X-34 would be capable of speeds up to Mach 8 and altitudes of 250,000-feet. The X-34 program was cancelled in 2001.

  1. Pathfinder

    NASA Image and Video Library

    2004-04-15

    This artist's concept depicts the X-34 Demonstrator sitting on a runway. Part of the Pathfinder Program, the X-34 was a reusable technology testbed vehicle that was designed and built by the Marshall Space Flight Center to demonstrate technologies that were essential to lowering the cost of access to space. Powered by a LOX and RP-1 liquid Fastrac engine, the X-34 would be capable of speeds up to Mach 8 and altitudes of 250,000-feet. The X-34 program was cancelled in 2001.

  2. Pathfinder

    NASA Image and Video Library

    2004-04-15

    Pictured is the X-34 Demonstrator parked on the runway. Part of the Pathfinder Program, the X-34 was a reusable technology testbed vehicle that was designed and built by the Marshall Space Flight Center to demonstrate technologies that are essential to lowering the cost of access to space. Powered by a LOX and RP-1 liquid Fastrac engine, the X-34 would be capable of speeds up to Mach 8 and altitudes of 250,000-feet. The X-34 program was cancelled in 2001.

  3. Pathfinder

    NASA Image and Video Library

    2004-04-15

    This artist's concept depicts the X-34 Demonstrator landing in a dessert. Part of the Pathfinder Program, the X-34 was a reusable technology testbed vehicle that was designed and built by the Marshall Space Flight Center to demonstrate technologies that were essential to lowering the cost of access to space. Powered by a LOX and RP-1 liquid Fastrac engine, the X-34 would be capable of speeds up to Mach 8 and altitudes of 250,000-feet. The X-34 program was cancelled in 2001.

  4. NASA's Chemical Transfer Propulsion Program for Pathfinder

    NASA Technical Reports Server (NTRS)

    Hannum, Ned P.; Berkopec, Frank D.; Zurawski, Robert L.

    1989-01-01

    Pathfinder is a research and technology project, with specific deliverables, initiated by the National Aeronautics and Space Administration (NASA) which will strengthen the technology base of the United States civil space program in preparation for future space exploration missions. Pathfinder begins in Fiscal Year 1989, and is to advance a collection of critical technologies for these missions and ensure technology readiness for future national decisions regarding exploration of the solar system. The four major thrusts of Pathfinder are: surface exploration, in-space operations, humans-in-space, and space transfer. The space transfer thrust will provide the critical technologies needed for transportation to, and return from, the Moon, Mars, and other planets in the solar system, as well as for reliable and cost-effective Earth-orbit operations. A key element of this thrust is the Chemical Transfer Propulsion program which will provide the propulsion technology for high performance, liquid oxygen/liquid hydrogen expander cycle engines which may be operated and maintained in space. Described here are the program overview including the goals and objectives, management, technical plan, and technology transfer for the Chemical Transfer Propulsion element of Pathfinder.

  5. MARS PATHFINDER CAMERA TEST IN SAEF-2

    NASA Technical Reports Server (NTRS)

    1996-01-01

    In the Spacecraft Assembly and Encapsulation Facility-2 (SAEF-2), workers from the Jet Propulsion Laboratory (JPL) are conducting a systems test of the imager for the Mars Pathfinder. The imager (white and metallic cylindrical element close to hand of worker at left) is a specially designed camera featuring a stereo- imaging system with color capability provided by a set of selectable filters. It is mounted atop an extendable mast on the Pathfinder lander. Visible to the far left is the small rover which will be deployed from the lander to explore the Martian surface. Transmitting back to Earth images of the trail left by the rover will be one of the mission objectives for the imager. To the left of the worker standing near the imager is the mast for the low-gain antenna; the round high-gain antenna is to the right. Visible in the background is the cruise stage that will carry the Pathfinder on a direct trajectory to Mars. The Mars Pathfinder is one of two Mars-bound spacecraft slated for launch aboard Delta II expendable launch vehicles this year.

  6. Pathfinder

    NASA Image and Video Library

    2004-04-15

    Pictured is NASA's poster art for the X-34 technology Demonstrator. The X-34 was part of NASA's Pathfinder Program which demonstrated advanced space transportation technologies through the use of flight experiments and experimental vehicles. These technology demonstrators and flight experiments would support the Agency's goal of dramatically reducing the cost of access to space and would define the future of space transportation pushing technology into a new era of space development and exploration at the dawn of the new century. The X-34 program was cancelled in 2001.

  7. Pathfinder

    NASA Image and Video Library

    2004-04-15

    Pictured in the high bay, is the X-34 Technology Demonstrator in the process of completion. The X-34 wass part of NASA's Pathfinder Program which demonstrated advanced space transportation technologies through the use of flight experiments and experimental vehicles. These technology demonstrators and flight experiments supported the Agency's goal of dramatically reducing the cost of access to space and defined the future of space transportation pushing technology into a new era of space development and exploration at the dawn of the new century. The X-34 program was cancelled in 2001.

  8. Characterization of the ionosphere above the Murchison Radio Observatory using the Murchison Widefield Array

    NASA Astrophysics Data System (ADS)

    Jordan, C. H.; Murray, S.; Trott, C. M.; Wayth, R. B.; Mitchell, D. A.; Rahimi, M.; Pindor, B.; Procopio, P.; Morgan, J.

    2017-11-01

    We detail new techniques for analysing ionospheric activity, using Epoch of Reionization data sets obtained with the Murchison Widefield Array, calibrated by the `real-time system' (RTS). Using the high spatial- and temporal-resolution information of the ionosphere provided by the RTS calibration solutions over 19 nights of observing, we find four distinct types of ionospheric activity, and have developed a metric to provide an `at a glance' value for data quality under differing ionospheric conditions. For each ionospheric type, we analyse variations of this metric as we reduce the number of pierce points, revealing that a modest number of pierce points is required to identify the intensity of ionospheric activity; it is possible to calibrate in real-time, providing continuous information of the phase screen. We also analyse temporal correlations, determine diffractive scales, examine the relative fractions of time occupied by various types of ionospheric activity and detail a method to reconstruct the total electron content responsible for the ionospheric data we observe. These techniques have been developed to be instrument agnostic, useful for application on LOw Frequency ARray and Square Kilometre Array-Low.

  9. High-Voltage High-Energy Stretched Lens Array Square-Rigger (SLASR) for Direct-Drive Solar Electric Propulsion

    NASA Technical Reports Server (NTRS)

    Howell, Joe T.; O'Neill, Mark J.; Mankins, John C.

    2006-01-01

    Development is underway on a unique high-voltage, high energy solar concentrator array called Stretched Lens Array Square-Rigger (SLASR) for direct drive electric propulsion. The SLASR performance attributes closely match the critical needs of solar electric propulsion (SEP) systems, which may be used for space tugs to fuel efficiently transport cargo from low earth orbit (LEO) to low lunar orbit (LLO), in support of NASA's robotic and human exploration missions. Later SEP systems may similarly transport cargo from the earth-moon neighborhood to the Mars neighborhood. This paper will describe the SLASR technology, discuss SLASR developments and ground testing, and outline plans for future SLASR technology maturation.

  10. High-Voltage High-Energy Stretched Lens Array Square-Rigger (SLASR) for Direct-Drive Solar Electric Propulsion

    NASA Technical Reports Server (NTRS)

    Howell, Joe T.; O'Neill, Mark; Mankins, John C.

    2006-01-01

    Development is underway on a unique high-voltage, high-energy solar concentrator array called Stretched Lens Array Square-Rigger (SLASR) for direct drive electric propulsion. The SLASR performance attributes closely match the critical needs of solar electric propulsion (SEP) systems, which may be used for space tugs to fuel-efficiently transport cargo from low earth orbit (LEO) to low lunar orbit (LLO), in support of NASA s robotic and human exploration missions. Later SEP systems may similarly transport cargo from the earth-moon neighborhood to the Mars neighborhood. This paper will describe the SLASR technology, discuss SLASR developments and ground testing, and outline plans for future SLASR technology maturation.

  11. Development of the AuScope Australian Earth Observing System

    NASA Astrophysics Data System (ADS)

    Rawling, T.

    2017-12-01

    Advances in monitoring technology and significant investment in new national research initiatives, will provide significant new opportunities for delivery of novel geoscience data streams from across the Australian continent over the next decade. The AuScope Australian Earth Observing System (AEOS) is linking field and laboratory infrastructure across Australia to form a national sensor array focusing on the Solid Earth. As such AuScope is working with these programs to deploy observational infrastructure, including MT, passive seismic, and GNSS networks across the entire Australian Continent. Where possible the observational grid will be co-located with strategic basement drilling in areas of shallow cover and tied with national reflection seismic and sampling transects. This integrated suite of distributed earth observation and imaging sensors will provide unprecedented imaging fidelity of our crust, across all length and time scales, to fundamental and applied researchers in the earth, environmental and geospatial sciences. The AEOS will the Earth Science community's Square Kilometer Array (SKA) - a distributed telescope that looks INTO the earth rather than away from it - a 10 million SKA. The AEOS is strongly aligned with other community strategic initiatives including the UNCOVER research program as well as other National Collaborative Research Infrastructure programs such as the Terrestrial Environmental Research Network (TERN) and the Integrated Marine Observing System (IMOS) providing an interdisciplinary collaboration platform across the earth and environmental sciences. There is also very close alignment between AuScope and similar international programs such as EPOS, the USArray and EarthCube - potential collaborative linkages we are currently in the process of pursuing more fomally. The AuScope AEOS Infrastructure System is ultimately designed to enable the progressive construction, refinement and ongoing enrichment of a live, "FAIR" four

  12. Weight Vector Fluctuations in Adaptive Antenna Arrays Tuned Using the Least-Mean-Square Error Algorithm with Quadratic Constraint

    NASA Astrophysics Data System (ADS)

    Zimina, S. V.

    2015-06-01

    We present the results of statistical analysis of an adaptive antenna array tuned using the least-mean-square error algorithm with quadratic constraint on the useful-signal amplification with allowance for the weight-coefficient fluctuations. Using the perturbation theory, the expressions for the correlation function and power of the output signal of the adaptive antenna array, as well as the formula for the weight-vector covariance matrix are obtained in the first approximation. The fluctuations are shown to lead to the signal distortions at the antenna-array output. The weight-coefficient fluctuations result in the appearance of additional terms in the statistical characteristics of the antenna array. It is also shown that the weight-vector fluctuations are isotropic, i.e., identical in all directions of the weight-coefficient space.

  13. Mathematical Construction of Magic Squares Utilizing Base-N Arithmetic

    ERIC Educational Resources Information Center

    O'Brien, Thomas D.

    2006-01-01

    Magic squares have been of interest as a source of recreation for over 4,500 years. A magic square consists of a square array of n[squared] positive and distinct integers arranged so that the sum of any column, row, or main diagonal is the same. In particular, an array of consecutive integers from 1 to n[squared] forming an nxn magic square is…

  14. Strategy for selecting Mars Pathfinder landing sites

    NASA Technical Reports Server (NTRS)

    Greeley, Ronald; Kuzmin, Ruslin O.

    1994-01-01

    A strategy for Pathfinder site selection must be developed that is fundamentally different from most previous considerations. At least two approaches can be identified. In one approach, the objective is to select a site representing a key geologic unit on Mars, i.e., a unit that is widespread, easily recognized, and used frequently as a datum in various investigations. The second approach is to select a site that potentially affords access to a wide variety of rock types. Because rover range is limited, rocks from a variety of sources must be assembled in a small area for sampling. Regardless of the approach taken in site selection, the Pathfinder site should include eolian deposits and provisions should be made to obtain measurements on soils. A recommended approach for selecting the Mars Pathfinder landing site is to identify a deltaic deposit, composed of sediments derived from sources of various ages and geologic units that shows evidence of eolian activity. The site should be located as close as possible to the part of the outwash where rapid deposition occurred because the likelihood of 'sorting' by size and composition increases with distance, decreasing the probability of heterogeneity. In addition, it is recommended that field operation tests be conducted to gain experience and insight into conducting science with Pathfinder.

  15. Drag-Free Performance of the ST7 Disturbance Reduction System Flight Experiment on the LISA Pathfinder

    NASA Technical Reports Server (NTRS)

    Maghami, Peiman G.; O'Donnell, James R.; Hsu, Oscar H.; Ziemer, John K.; Dunn, Charles E.

    2017-01-01

    The Space Technology-7 Disturbance Reduction System (DRS) is an experiment package aboard the European Space Agency (ESA) LISA Pathfinder spacecraft. LISA Pathfinder launched from Kourou, French Guiana on December 3, 2015. The DRS is tasked to validate two specific technologies: colloidal micro-Newton thrusters (CMNT) to provide low-noise control capability of the spacecraft, and drag-free controlflight. This validation is performed using highly sensitive drag-free sensors, which are provided by the LISA Technology Package of the European Space Agency. The Disturbance Reduction System is required to maintain the spacecrafts position with respect to a free-floating test mass to better than 10nm/(square root of Hz), along its sensitive axis (axis in optical metrology). It also has a goal of limiting the residual accelerations of any of the two test masses to below 30 x 10(exp -14) (1 + ([f/3 mHz](exp 2))) m/sq s/(square root of Hz), over the frequency range of 1 to 30 mHz.This paper briefly describes the design and the expected on-orbit performance of the control system for the two modes wherein the drag-free performance requirements are verified. The on-orbit performance of these modes are then compared to the requirements, as well as to the expected performance, and discussed.

  16. The Pathfinder Microrover

    NASA Technical Reports Server (NTRS)

    Matijevic, J. R.; Bickler, D. B.; Braun, D. F.; Eisen, H. J.; Matthies, L. H.; Mishkin, A. H.; Stone, H. W.; van Nieuwstadt, L. M.; Wen, L. C.; Wilcox, B. H.; hide

    1996-01-01

    An exciting scientific component of the Pathfinder mission is the rover, which will act as a mini-field geologist by providing us with access to samples for chemical analyses and close-up images of the Martian surface, performing active experiments to modify the surface and study the results, and exploring the landing site area.

  17. Observing the Extragalactic Universe with a Square Kilometer Array

    NASA Astrophysics Data System (ADS)

    Blandford, R. D.

    2001-12-01

    The Square Kilometer Array, SKA, is being developed to provide broad, radio survey capability to cm wavelength, with a 1 degree field of view, 1 arcsec resolution and 100 times the VLA sensitivity. In extragalactic astronomy, it will observe unobscured, normal and active galaxies, star formation and mergers, large scale structure and gravitational lenses throughout the universe. It will contribute mightily to our emerging, empirical description of the birth and growth of galaxies of all type. It should also advance our understanding of the conditions that existed prior to galaxy formation at the end of the dark age and help delineate the dark matter skeleton that supports mature galaxies. It will map and monitor, in quite different modes, the same objects as Chandra, SIRTF, HST/ACS, GLAST, SDSS as well as future missions like NGST and Constellation-X. The proposed scientific capability of SKA will be summarized. In addition, the importance of refining its goals and design criteria in a dialog with organizations making complementary plans throughout the electromagnetic spectrum will be emphasized.

  18. Mars Pathfinder Rover-Lewis Research Center Technology Experiments Program

    NASA Technical Reports Server (NTRS)

    Stevenson, Steven M.

    1997-01-01

    An overview of NASA's Mars Pathfinder Program is given and the development and role of three technology experiments from NASA's Lewis Research Center and carried on the Mars Pathfinder rover is described. Two recent missions to Mars were developed and managed by the Jet Propulsion Laboratory, and launched late last year: Mars Global Surveyor in November 1996 and Mars Pathfinder in December 1996. Mars Global Surveyor is an orbiter which will survey the planet with a number of different instruments, and will arrive in September 1997, and Mars Pathfinder which consists of a lander and a small rover, landing on Mars July 4, 1997. These are the first two missions of the Mars Exploration Program consisting of a ten year series of small robotic martian probes to be launched every 26 months. The Pathfinder rover will perform a number of technology and operational experiments which will provide the engineering information necessary to design and operate more complex, scientifically oriented surface missions involving roving vehicles and other machinery operating in the martian environment. Because of its expertise in space power systems and technologies, space mechanisms and tribology, Lewis Research Center was asked by the Jet Propulsion Laboratory, which is heading the Mars Pathfinder Program, to contribute three experiments concerning the effects of the martian environment on surface solar power systems and the abrasive qualities of the Mars surface material. In addition, rover static charging was investigated and a static discharge system of several fine Tungsten points was developed and fixed to the rover. These experiments and current findings are described herein.

  19. Pulsar Timing Array Based Search for Supermassive Black Hole Binaries in the Square Kilometer Array Era

    NASA Astrophysics Data System (ADS)

    Wang, Yan; Mohanty, Soumya D.

    2017-04-01

    The advent of next generation radio telescope facilities, such as the Square Kilometer Array (SKA), will usher in an era where a pulsar timing array (PTA) based search for gravitational waves (GWs) will be able to use hundreds of well timed millisecond pulsars rather than the few dozens in existing PTAs. A realistic assessment of the performance of such an extremely large PTA must take into account the data analysis challenge posed by an exponential increase in the parameter space volume due to the large number of so-called pulsar phase parameters. We address this problem and present such an assessment for isolated supermassive black hole binary (SMBHB) searches using a SKA era PTA containing 1 03 pulsars. We find that an all-sky search will be able to confidently detect nonevolving sources with a redshifted chirp mass of 1 010 M⊙ out to a redshift of about 28 (corresponding to a rest-frame chirp mass of 3.4 ×1 08 M⊙). We discuss the important implications that the large distance reach of a SKA era PTA has on GW observations from optically identified SMBHB candidates. If no SMBHB detections occur, a highly unlikely scenario in the light of our results, the sky-averaged upper limit on strain amplitude will be improved by about 3 orders of magnitude over existing limits.

  20. Pulsar Timing Array Based Search for Supermassive Black Hole Binaries in the Square Kilometer Array Era.

    PubMed

    Wang, Yan; Mohanty, Soumya D

    2017-04-14

    The advent of next generation radio telescope facilities, such as the Square Kilometer Array (SKA), will usher in an era where a pulsar timing array (PTA) based search for gravitational waves (GWs) will be able to use hundreds of well timed millisecond pulsars rather than the few dozens in existing PTAs. A realistic assessment of the performance of such an extremely large PTA must take into account the data analysis challenge posed by an exponential increase in the parameter space volume due to the large number of so-called pulsar phase parameters. We address this problem and present such an assessment for isolated supermassive black hole binary (SMBHB) searches using a SKA era PTA containing 10^{3} pulsars. We find that an all-sky search will be able to confidently detect nonevolving sources with a redshifted chirp mass of 10^{10}  M_{⊙} out to a redshift of about 28 (corresponding to a rest-frame chirp mass of 3.4×10^{8}  M_{⊙}). We discuss the important implications that the large distance reach of a SKA era PTA has on GW observations from optically identified SMBHB candidates. If no SMBHB detections occur, a highly unlikely scenario in the light of our results, the sky-averaged upper limit on strain amplitude will be improved by about 3 orders of magnitude over existing limits.

  1. Massive formation of square array junctions dramatically alters cell shape but does not cause lens opacity in the cav1-KO mice.

    PubMed

    Biswas, Sondip K; Brako, Lawrence; Lo, Woo-Kuen

    2014-08-01

    The wavy square array junctions are composed of truncated aquaporin-0 (AQP0) proteins typically distributed in the deep cortical and nuclear fibers in wild-type lenses. These junctions may help maintain the narrowed extracellular spaces between fiber cells to minimize light scattering. Herein, we investigate the impact of the cell shape changes, due to abnormal formation of extensive square array junctions, on the lens opacification in the caveolin-1 knockout mice. The cav1-KO and wild-type mice at age 1-22 months were used. By light microscopy examinations, cav1-KO lenses at age 1-18 months were transparent in both cortical and nuclear regions, whereas some lenses older than 18 months old exhibited nuclear cataracts. Scanning EM consistently observed the massive formation of ridge-and-valley membrane surfaces in young fibers at approximately 150 μm deep in all cav1-KO lenses studied. In contrast, the typical ridge-and-valleys were only seen in mature fibers deeper than 400 μm in wild-type lenses. The resulting extensive ridge-and-valleys dramatically altered the overall cell shape in cav1-KO lenses. Remarkably, despite dramatic shape changes, these deformed fiber cells remained intact and made close contact with their neighboring cells. By freeze-fracture TEM, ridge-and-valleys exhibited the typical orthogonal arrangement of 6.6 nm square array intramembrane particles and displayed the narrowed extracellular spaces. Immunofluorescence analysis showed that AQP0 C-terminus labeling was significantly decreased in outer cortical fibers in cav1-KO lenses. However, freeze-fracture immunogold labeling showed that the AQP0 C-terminus antibody was sparsely distributed on the wavy square array junctions, suggesting that the cleavage of AQP0 C-termini might not yet be complete. The cav1-KO lenses with nuclear cataracts showed complete cellular breakdown and large globule formation in the lens nucleus. This study suggests that despite dramatic cell shape changes, the

  2. The semantic pathfinder: using an authoring metaphor for generic multimedia indexing.

    PubMed

    Snoek, Cees G M; Worring, Marcel; Geusebroek, Jan-Mark; Koelma, Dennis C; Seinstra, Frank J; Smeulders, Arnold W M

    2006-10-01

    This paper presents the semantic pathfinder architecture for generic indexing of multimedia archives. The semantic pathfinder extracts semantic concepts from video by exploring different paths through three consecutive analysis steps, which we derive from the observation that produced video is the result of an authoring-driven process. We exploit this authoring metaphor for machine-driven understanding. The pathfinder starts with the content analysis step. In this analysis step, we follow a data-driven approach of indexing semantics. The style analysis step is the second analysis step. Here, we tackle the indexing problem by viewing a video from the perspective of production. Finally, in the context analysis step, we view semantics in context. The virtue of the semantic pathfinder is its ability to learn the best path of analysis steps on a per-concept basis. To show the generality of this novel indexing approach, we develop detectors for a lexicon of 32 concepts and we evaluate the semantic pathfinder against the 2004 NIST TRECVID video retrieval benchmark, using a news archive of 64 hours. Top ranking performance in the semantic concept detection task indicates the merit of the semantic pathfinder for generic indexing of multimedia archives.

  3. Correlation between terrestrial myriametric and kilometric radio bursts observed with Galileo

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

    Louarn, P.; Hilgers, A.; Roux, A.

    The authors present results from wave measurements made by Galileo on transects of the magnetotail between R{sub e} of 30 and 80. They observe radiation in the myriametric and kilometric range. The myriametric radition has a continuous components, and a burstly component which correlated with the bursty nature of the kilometric radiation, originating on auroral field lines much closer to the earth. They present a mechanism to account for this wave activity, and its frequency dependence.

  4. Sets of Mutually Orthogonal Sudoku Latin Squares

    ERIC Educational Resources Information Center

    Vis, Timothy; Petersen, Ryan M.

    2009-01-01

    A Latin square of order "n" is an "n" x "n" array using n symbols, such that each symbol appears exactly once in each row and column. A set of Latin squares is c ordered pairs of symbols appearing in the cells of the array are distinct. The popular puzzle Sudoku involves Latin squares with n = 9, along with the added condition that each of the 9…

  5. LISA Pathfinder: A Mission Status

    NASA Astrophysics Data System (ADS)

    Hewitson, Martin; LISA Pathfinder Team Team

    2016-03-01

    On December 3rd at 04:04 UTC, The European Space Agency launched the LISA Pathfinder satellite on board a VEGA rocket from Kourou in French Guiana. After a series of orbit raising manoeuvres and a 2 month long transfer orbit, LISA Pathfinder arrived at L1. Following a period of commissioning, the science operations commenced at the start of March, beginning the demonstration of technologies and methodologies which pave the way for a future large-scale gravitational wave observatory in space. This talk will present the scientific goals of the mission, discuss the technologies being tested, elucidate the link to a future space-based observatory, such as LISA, and present preliminary results from the in-orbit operations and experiments.

  6. A review of parameters and heuristics for guiding metabolic pathfinding.

    PubMed

    Kim, Sarah M; Peña, Matthew I; Moll, Mark; Bennett, George N; Kavraki, Lydia E

    2017-09-15

    Recent developments in metabolic engineering have led to the successful biosynthesis of valuable products, such as the precursor of the antimalarial compound, artemisinin, and opioid precursor, thebaine. Synthesizing these traditionally plant-derived compounds in genetically modified yeast cells introduces the possibility of significantly reducing the total time and resources required for their production, and in turn, allows these valuable compounds to become cheaper and more readily available. Most biosynthesis pathways used in metabolic engineering applications have been discovered manually, requiring a tedious search of existing literature and metabolic databases. However, the recent rapid development of available metabolic information has enabled the development of automated approaches for identifying novel pathways. Computer-assisted pathfinding has the potential to save biochemists time in the initial discovery steps of metabolic engineering. In this paper, we review the parameters and heuristics used to guide the search in recent pathfinding algorithms. These parameters and heuristics capture information on the metabolic network structure, compound structures, reaction features, and organism-specificity of pathways. No one metabolic pathfinding algorithm or search parameter stands out as the best to use broadly for solving the pathfinding problem, as each method and parameter has its own strengths and shortcomings. As assisted pathfinding approaches continue to become more sophisticated, the development of better methods for visualizing pathway results and integrating these results into existing metabolic engineering practices is also important for encouraging wider use of these pathfinding methods.

  7. VR for Mars Pathfinder

    NASA Technical Reports Server (NTRS)

    Blackmon, Theodore

    1998-01-01

    Virtual reality (VR) technology has played an integral role for Mars Pathfinder mission, operations Using an automated machine vision algorithm, the 3d topography of the Martian surface was rapidly recovered fro -a the stereo images captured. by the Tender camera to produce photo-realistic 3d models, An advanced, interface was developed for visualization and interaction with. the virtual environment of the Pathfinder landing site for mission scientists at the Space Flight Operations Facility of the Jet Propulsion Laboratory. The VR aspect of the display allowed mission scientists to navigate on Mars in Bud while remaining here on Earth, thus improving their spatial awareness of the rock field that surrounds the lenders Measurements of positions, distances and angles could be easily extracted from the topographic models, providing valuable information for science analysis and mission. planning. Moreover, the VR map of Mars has also been used to assist with the archiving and planning of activities for the Sojourner rover.

  8. Simulation and Testing of a Linear Array of Modified Four-Square Feed Antennas for the Tianlai Cylindrical Radio Telescope

    NASA Astrophysics Data System (ADS)

    Cianciara, Aleksander J.; Anderson, Christopher J.; Chen, Xuelei; Chen, Zhiping; Geng, Jingchao; Li, Jixia; Liu, Chao; Liu, Tao; Lu, Wing; Peterson, Jeffrey B.; Shi, Huli; Steffel, Catherine N.; Stebbins, Albert; Stucky, Thomas; Sun, Shijie; Timbie, Peter T.; Wang, Yougang; Wu, Fengquan; Zhang, Juyong

    A wide bandwidth, dual polarized, modified four-square antenna is presented as a feed antenna for radio astronomical measurements. A linear array of these antennas is used as a line-feed for cylindrical reflectors for Tianlai, a radio interferometer designed for 21cm intensity mapping. Simulations of the feed antenna beam patterns and scattering parameters are compared to experimental results at multiple frequencies across the 650-1420MHz range. Simulations of the beam patterns of the combined feed array/reflector are presented as well.

  9. Assessment of Mars Pathfinder landing site predictions

    USGS Publications Warehouse

    Golombek, M.P.; Moore, H.J.; Haldemann, A.F.C.; Parker, T.J.; Schofield, J.T.

    1999-01-01

    Remote sensing data at scales of kilometers and an Earth analog were used to accurately predict the characteristics of the Mars Pathfinder landing site at a scale of meters. The surface surrounding the Mars Pathfinder lander in Ares Vallis appears consistent with orbital interpretations, namely, that it would be a rocky plain composed of materials deposited by catastrophic floods. The surface and observed maximum clast size appears similar to predictions based on an analogous surface of the Ephrata Fan in the Channeled Scabland of Washington state. The elevation of the site measured by relatively small footprint delay-Doppler radar is within 100 m of that determined by two-way ranging and Doppler tracking of the spacecraft. The nearly equal elevations of the Mars Pathfinder and Viking Lander 1 sites allowed a prediction of the atmospheric conditions with altitude (pressure, temperature, and winds) that were well within the entry, descent, and landing design margins. High-resolution (~38 m/pixel) Viking Orbiter 1 images showed a sparsely cratered surface with small knobs with relatively low slopes, consistent with observations of these features from the lander. Measured rock abundance is within 10% of that expected from Viking orbiter thermal observations and models. The fractional area covered by large, potentially hazardous rocks observed is similar to that estimated from model rock distributions based on data from the Viking landing sites, Earth analog sites, and total rock abundance. The bulk and fine-component thermal inertias measured from orbit are similar to those calculated from the observed rock size-frequency distribution. A simple radar echo model based on the reflectivity of the soil (estimated from its bulk density), and the measured fraction of area covered by rocks was used to approximate the quasi-specular and diffuse components of the Earth-based radar echos. Color and albedo orbiter data were used to predict the relatively dust free or unweathered

  10. LISA Pathfinder Spacecraft Artist Concept

    NASA Image and Video Library

    2015-12-03

    This artist's concept shows ESA's LISA Pathfinder spacecraft, which launched on Dec. 3, 2015, from Kourou, French Guiana, will help pave the way for a mission to detect gravitational waves. LISA Pathfinder, led by the European Space Agency (ESA), is designed to test technologies that could one day detect gravitational waves. Gravitational waves, predicted by Einstein's theory of general relativity, are ripples in spacetime produced by any accelerating body. But the waves are so weak that Earth- or space-based observatories would likely only be able to directly detect such signals coming from massive astronomical systems, such as binary black holes or exploding stars. Detecting gravitational waves would be an important piece in the puzzle of how our universe began. http://photojournal.jpl.nasa.gov/catalog/PIA20196

  11. Pathfinder Innovation Projects: Awardees 2015

    EPA Pesticide Factsheets

    The Pathfinder program supports high-risk, high-reward research ideas with funding and staff time. The goal is to feed a culture of innovation in the Agency and integrate innovative ideas in EPA research programs.

  12. Pathfinder Innovation Projects: Awardees 2016

    EPA Pesticide Factsheets

    The Pathfinder program supports high-risk, high-reward research ideas with funding and staff time. The goal is to feed a culture of innovation in the Agency and integrate innovative ideas in EPA research programs.

  13. Pathfinder Instruments for Cloud and Aerosol Spaceborne Observations (PICASSO)

    NASA Technical Reports Server (NTRS)

    McCormick, M. Patrick; Winker, David M.

    1998-01-01

    This paper will describe the planned 3-year Pathfinder Instruments for Cloud and Aerosol Spaceborne Observations (PICASSO) mission, its instrumentation and implementation. It will use LITE and other data, plus analyses, to show the feasibility of such a mission. PICASSO is being proposed for NASA's Earth System Science Pathfinder (ESSP) program with launch predicted in 2003.

  14. Overhead View of Area Surrounding Pathfinder

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Overhead view of the area surrounding the Pathfinder lander illustrating the Sojourner traverse. Red rectangles are rover positions at the end of sols 1-30. Locations of soil mechanics experiments, wheel abrasion experiments, and APXS measurements are shown. The A numbers refer to APXS measurements as discussed in the paper by Rieder et al. (p. 1770, Science Magazine, see image note). Coordinates are given in the LL frame.

    The photorealistic, interactive, three-dimensional virtual reality (VR) terrain models were created from IMP images using a software package developed for Pathfinder by C. Stoker et al. as a participating science project. By matching features in the left and right camera, an automated machine vision algorithm produced dense range maps of the nearfield, which were projected into a three-dimensional model as a connected polygonal mesh. Distance and angle measurements can be made on features viewed in the model using a mouse-driven three-dimensional cursor and a point-and-click interface. The VR model also incorporates graphical representations of the lander and rover and the sequence and spatial locations at which rover data were taken. As the rover moved, graphical models of the rover were added for each position that could be uniquely determined using stereo images of the rover taken by the IMP. Images taken by the rover were projected into the model as two-dimensional 'billboards' to show the proper perspective of these images.

    NOTE: original caption as published in Science Magazine

    Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology (Caltech).

  15. Quantum teleportation and entanglement distribution over 100-kilometre free-space channels.

    PubMed

    Yin, Juan; Ren, Ji-Gang; Lu, He; Cao, Yuan; Yong, Hai-Lin; Wu, Yu-Ping; Liu, Chang; Liao, Sheng-Kai; Zhou, Fei; Jiang, Yan; Cai, Xin-Dong; Xu, Ping; Pan, Ge-Sheng; Jia, Jian-Jun; Huang, Yong-Mei; Yin, Hao; Wang, Jian-Yu; Chen, Yu-Ao; Peng, Cheng-Zhi; Pan, Jian-Wei

    2012-08-09

    Transferring an unknown quantum state over arbitrary distances is essential for large-scale quantum communication and distributed quantum networks. It can be achieved with the help of long-distance quantum teleportation and entanglement distribution. The latter is also important for fundamental tests of the laws of quantum mechanics. Although quantum teleportation and entanglement distribution over moderate distances have been realized using optical fibre links, the huge photon loss and decoherence in fibres necessitate the use of quantum repeaters for larger distances. However, the practical realization of quantum repeaters remains experimentally challenging. Free-space channels, first used for quantum key distribution, offer a more promising approach because photon loss and decoherence are almost negligible in the atmosphere. Furthermore, by using satellites, ultra-long-distance quantum communication and tests of quantum foundations could be achieved on a global scale. Previous experiments have achieved free-space distribution of entangled photon pairs over distances of 600 metres (ref. 14) and 13 kilometres (ref. 15), and transfer of triggered single photons over a 144-kilometre one-link free-space channel. Most recently, following a modified scheme, free-space quantum teleportation over 16 kilometres was demonstrated with a single pair of entangled photons. Here we report quantum teleportation of independent qubits over a 97-kilometre one-link free-space channel with multi-photon entanglement. An average fidelity of 80.4 ± 0.9 per cent is achieved for six distinct states. Furthermore, we demonstrate entanglement distribution over a two-link channel, in which the entangled photons are separated by 101.8 kilometres. Violation of the Clauser-Horne-Shimony-Holt inequality is observed without the locality loophole. Besides being of fundamental interest, our results represent an important step towards a global quantum network. Moreover, the high

  16. Using Web2.0 Applications to Close the Digital Divide in Western Australia

    ERIC Educational Resources Information Center

    Trinidad, Sue; Broadley, Tania

    2008-01-01

    The research reported in this paper documents the use of Web2.0 applications with six Western Australian schools that are considered to be regional and/or remote. With a population of two million people within an area of 2,525,500 square kilometres Western Australia has a number of towns that are classified as regional and remote. Each of the…

  17. Building contacts for the SKA

    NASA Astrophysics Data System (ADS)

    Bowler, Sue

    2016-06-01

    The Square Kilometre Array needs industrial expertise; SKA technology will, in turn, streamline big-data challenges for business and society. Or that's the idea: Sue Bowler reports on a day of networking designed to build industry-academia collaborations in the UK.

  18. Buckling failure of square ice-nanotube arrays constrained in graphene nanocapillaries.

    PubMed

    Zhu, YinBo; Wang, FengChao; Wu, HengAn

    2016-08-07

    Graphene confinement provides a new physical and mechanical environment with ultrahigh van der Waals pressure, resulting in new quasi-two-dimensional phases of few-layer ice. Polymorphic transition can occur in bilayer constrained water/ice system. Here, we perform a comprehensive study of the phase transition of AA-stacked bilayer water constrained within a graphene nanocapillary. The compression-limit and superheating-limit (phase) diagrams are obtained, based on the extensive molecular-dynamics simulations at numerous thermodynamic states. Liquid-to-solid, solid-to-solid, and solid-to-liquid-to-solid phase transitions are observed in the compression and superheating of bilayer water. Interestingly, there is a temperature threshold (∼275 K) in the compression-limit diagram, which indicates that the first-order and continuous-like phase transitions of bilayer water depend on the temperature. Two obviously different physical processes, compression and superheating, display similar structural evolution; that is, square ice-nanotube arrays (BL-VHDI) will bend first and then transform into bilayer triangular AA stacking ice (BL-AAI). The superheating limit of BL-VHDI exhibits local maxima, while that of BL-AAI increases monotonically. More importantly, from a mechanics point of view, we propose a novel mechanism of the transformation from BL-VHDI to BL-AAI, both for the compression and superheating limits. This structural transformation can be regarded as the "buckling failure" of the square-ice-nanotube columns, which is dominated by the lateral pressure.

  19. Buckling failure of square ice-nanotube arrays constrained in graphene nanocapillaries

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

    Zhu, YinBo; Wang, FengChao, E-mail: wangfc@ustc.edu.cn; Wu, HengAn

    Graphene confinement provides a new physical and mechanical environment with ultrahigh van der Waals pressure, resulting in new quasi-two-dimensional phases of few-layer ice. Polymorphic transition can occur in bilayer constrained water/ice system. Here, we perform a comprehensive study of the phase transition of AA-stacked bilayer water constrained within a graphene nanocapillary. The compression-limit and superheating-limit (phase) diagrams are obtained, based on the extensive molecular-dynamics simulations at numerous thermodynamic states. Liquid-to-solid, solid-to-solid, and solid-to-liquid-to-solid phase transitions are observed in the compression and superheating of bilayer water. Interestingly, there is a temperature threshold (∼275 K) in the compression-limit diagram, which indicates thatmore » the first-order and continuous-like phase transitions of bilayer water depend on the temperature. Two obviously different physical processes, compression and superheating, display similar structural evolution; that is, square ice-nanotube arrays (BL-VHDI) will bend first and then transform into bilayer triangular AA stacking ice (BL-AAI). The superheating limit of BL-VHDI exhibits local maxima, while that of BL-AAI increases monotonically. More importantly, from a mechanics point of view, we propose a novel mechanism of the transformation from BL-VHDI to BL-AAI, both for the compression and superheating limits. This structural transformation can be regarded as the “buckling failure” of the square-ice-nanotube columns, which is dominated by the lateral pressure.« less

  20. The Mars Pathfinder Mission and Science Results

    NASA Technical Reports Server (NTRS)

    Golombek, M. P.

    1999-01-01

    Mars Pathfinder, the first low-cost, quick Discovery class mission to be completed, successfully landed on the surface of Mars on July 4, 1997, deployed and navigated a small rover, and collected data from 3 science instruments and 10 technology experiments. The mission operated on Mars for 3 months and returned 2.3 Gbits of new data, including over 16,500 lander and 550 rover images, 16 chemical analyses of rocks and soil, and 8.5 million individual temperature, pressure and wind measurements. The rover traversed 100 m clockwise around the lander, exploring about 200 square meters of the surface. The mission captured the imagination of the public, and garnered front page headlines during the first week. A total of about 566 million internet "hits" were registered during the first month of the mission, with 47 million "hits" on July 8th alone, making the Pathfinder landing by far the largest internet event in history at the time. Pathfinder was the first mission to deploy a rover on Mars. It carried a chemical analysis instrument, to characterize the rocks and soils in a landing area over hundreds of square meters on Mars, which provided a calibration point or "ground truth" for orbital remote sensing observations. The combination of spectral imaging of the landing area by the lander camera, chemical analyses aboard the rover, and close-up imaging of colors, textures and fabrics with the rover cameras offered the potential of identifying rocks (petrology and mineralogy). With this payload, a landing site in Ares Vallis was selected because it appeared acceptably safe and offered the prospect of analyzing a variety of rock types expected to be deposited by catastrophic floods, which enabled addressing first-order scientific questions such as differentiation of the crust, the development of weathering products, and the nature of the early Martian environment and its subsequent evolution. The 3 instruments and rover allowed seven areas of scientific investigation: the

  1. AVHRR-Based Polar Pathfinder Products: Evaluation, Enhancement, and Transition to MODIS

    NASA Technical Reports Server (NTRS)

    Fowler, Charles; Maslanik, James; Stone, Robert; Stroeve, Julienne; Emery, William

    2001-01-01

    The AVHRR-Based Polar Pathfinder (APP) products include calibrated AVHRR channel data, surface temperatures, albedo, satellite scan and solar geometries, and a cloud mask composited into twice- per-day images, and daily averaged fields of sea ice motion, for regions poleward of 50 deg. latitude. Our goals under this grant, in general, are four-fold: 1. To quantify the APP accuracy and sources of error by comparing Pathfinder products with field measurements. 2. To determine the consistency of mean fields and trends in comparison with longer time series of available station data and forecast model output. 3. To investigate the consistency of the products between the different AVHRR instruments over the 1982-present period of the NOAA program. 4. To compare an annual cycle of the AVHRR Pathfinder products with MODIS to establish a baseline for extending Pathfinder-type products into the new ESE period. Year One tasks include intercomparisons of the Pathfinder products with field measurements, testing of algorithm assumptions, collection of field data, and further validation and possible improvement of the multi-sensor ice motion fields. Achievements for these tasks are summarized below.

  2. MARS PATHFINDER AIR BAG INSTALLATION IN SAEF-2

    NASA Technical Reports Server (NTRS)

    1996-01-01

    In the Spacecraft Assembly and Encapsulation Facility-2 (SAEF-2), the Jet Propulsion Laboratory (JPL) team installs air bags on the Mars Pathfinder lander. The four airbags will cushion the lander as it touches down on the Martian surface, protecting the delicate instruments and Surveyor small rover inside the tetrahedral-shaped lander. The Mars Pathfinder is one of two Mars-bound spacecraft being prepared for launch this fall. Liftoff is set for Dec. 2 at the beginning of a 24-day launch period.

  3. The minimum bandwidths of auroral kilometric radiation

    NASA Technical Reports Server (NTRS)

    Baumback, M. M.; Calvert, W.

    1987-01-01

    The bandwidths of the discrete spectral components of the auroral kilometric radiation can sometimes be as narrow as 5 Hz. Since this would imply an apparent source thickness of substantially less than the wavelength, it is inconsistent with the previous explanation for such discrete components based simply upon vertical localization of a cyclotron source. Instead, such narrow bandwidths can only be explained by radio lasing.

  4. SLS Pathfinder Segments Car Train Departure

    NASA Image and Video Library

    2016-03-02

    An Iowa Northern locomotive, contracted by Goodloe Transportation of Chicago, departs from NASA’s Kennedy Space Center in Florida, with two containers on railcars for transport to the Jay Jay railroad yard. The containers held two pathfinders, or test versions, of solid rocket booster segments for NASA’s Space Launch System rocket that were delivered to the Rotation, Processing and Surge Facility (RPSF). Inside the RPSF, the Ground Systems Development and Operations Program and Jacobs Engineering, on the Test and Operations Support Contract, will conduct a series of lifts, moves and stacking operations using the booster segments, which are inert, to prepare for Exploration Mission-1, deep-space missions and the journey to Mars. The pathfinder booster segments are from Orbital ATK in Utah.

  5. Strain induced plasmon tuning in planar square-shaped aluminum nanoparticles array

    NASA Astrophysics Data System (ADS)

    Mokkath, Junais Habeeb

    2018-06-01

    Metal nanoparticle aggregate is an exciting platform for manipulating light-matter interactions at the nanoscale, thanks to the optically driven free electrons couple electrically across the inter-particle gap region. We use time dependent density functional theory calculations to investigate the optical response modulations in planar square-shaped aluminum nanoparticles array via morphology deformation (varying the inter-particle gap distance in the range of 2-20 Å) separately along one and two directions. We report the surprising observation that irrespective of the different morphology deformations, there exists a unique inter-particle gap distance of 12 Å for which, a maximum optical field enhancement can be achieved. We remark that plasmonic interaction between metal nanoparticles in an aggregate is controlled to a large extent by the size of the inter-particle gap distance. We believe that our quantum mechanical calculations will inspire and contribute to the design, control, and exploitation of aluminum based plasmonic devices.

  6. Multispectral Imaging from Mars PATHFINDER

    NASA Technical Reports Server (NTRS)

    Ferrand, William H.; Bell, James F., III; Johnson, Jeffrey R.; Bishop, Janice L.; Morris, Richard V.

    2007-01-01

    The Imager for Mars Pathfinder (IMP) was a mast-mounted instrument on the Mars Pathfinder lander which landed on Mars Ares Vallis floodplain on July 4, 1997. During the 83 sols of Mars Pathfinders landed operations, the IMP collected over 16,600 images. Multispectral images were collected using twelve narrowband filters at wavelengths between 400 and 1000 nm in the visible and near infrared (VNIR) range. The IMP provided VNIR spectra of the materials surrounding the lander including rocks, bright soils, dark soils, and atmospheric observations. During the primary mission, only a single primary rock spectral class, Gray Rock, was recognized; since then, Black Rock, has been identified. The Black Rock spectra have a stronger absorption at longer wavelengths than do Gray Rock spectra. A number of coated rocks have also been described, the Red and Maroon Rock classes, and perhaps indurated soils in the form of the Pink Rock class. A number of different soil types were also recognized with the primary ones being Bright Red Drift, Dark Soil, Brown Soil, and Disturbed Soil. Examination of spectral parameter plots indicated two trends which were interpreted as representing alteration products formed in at least two different environmental epochs of the Ares Vallis area. Subsequent analysis of the data and comparison with terrestrial analogs have supported the interpretation that the rock coatings provide evidence of earlier martian environments. However, the presence of relatively uncoated examples of the Gray and Black rock classes indicate that relatively unweathered materials can persist on the martian surface.

  7. MARS PATHFINDER CAMERA TEST IN SAEF-2

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Jet Propulsion Laboratory (JPL) workers conduct a systems test of the Mars Pathfinder imager, installed atop the Pathfinder lander (with JPL insignia). The imager is the white cyclindrical structure close to the worker's gloved hand. At left is the small rover that will be deployed from the lander to explore the Martian surface. The rover is mounted on one of three petals that will be attached to the lander. The two-pronged mast extending upward from the lander is for the low-gain antenna. The imager is mounted on a mast that will be extended after the lander touches down on Mars, affording a better view of the area. The imager is a camera that will transmit images of the Martian surface as well as the trail left by the rover, helping researchers to better understand the composition of the soil. It also is equipped with selectable filters for gathering data about the atmosphere of the Red Planet. JPL manages the Mars Pathfinder project for NASA. The journey to Mars is scheduled to begin with liftoff Dec. 2 aboard a Delta II expendable launch vehicle.

  8. Mars Pathfinder [foldout].

    PubMed

    1997-12-05

    The following foldout present images and analysis from the Mars Pathfinder Mission that are discussed in seven subsequent Reports. The center is a four-page panorama of the surface of Mars around the lander (Plate 1). The back of the foldout contains surface images (Plate 7), a different perspective of the landing site (Plate 2), rover targets (Plate 3), locations of rocks and other features (Plate 6) and data analysis (Plates 4, 4, 8, 9, and 10).

  9. RF Design of a Wideband CMOS Integrated Receiver for Phased Array Applications

    NASA Astrophysics Data System (ADS)

    Jackson, Suzy A.

    2004-06-01

    New silicon CMOS processes developed primarily for the burgeoning wireless networking market offer significant promise as a vehicle for the implementation of highly integrated receivers, especially at the lower end of the frequency range proposed for the Square Kilometre Array (SKA). An RF-CMOS ‘Receiver-on-a-Chip’ is being developed as part of an Australia Telescope program looking at technologies associated with the SKA. The receiver covers the frequency range 500 1700 MHz, with instantaneous IF bandwidth of 500 MHz and, on simulation, yields an input noise temperature of < 50 K at mid-band. The receiver will contain all active circuitry (LNA, bandpass filter, quadrature mixer, anti-aliasing filter, digitiser and serialiser) on one 0.18 μm RF-CMOS integrated circuit. This paper outlines receiver front-end development work undertaken to date, including design and simulation of an LNA using noise cancelling techniques to achieve a wideband input-power-match with little noise penalty.

  10. Morning Martian Atmospheric Temperature Gradients and Fluctuations Observed by Mars Pathfinder

    NASA Technical Reports Server (NTRS)

    Mihalov, John D.; Haberle, R. M.; Murphy, J. R.; Seiff, A.; Wilson, G. R.

    1999-01-01

    We have studied the most prominent atmospheric temperature fluctuations observed during Martian mornings by Mars Pathfinder and have concluded, based on comparisons with wind directions, that they appear to be a result of atmospheric heating associated with the Lander spacecraft. Also, we have examined the morning surface layer temperature lapse rates, which are found to decrease as autumn approaches at the Pathfinder location, and which have mean (and median) values as large as 7.3 K/m in the earlier portions of the Pathfinder landed mission. It is plausible that brief isolated periods with gradients twice as steep are associated with atmospheric heating adjacent to Lander air bag material. In addition, we have calculated the gradient with height of the structure function obtained with Mars Pathfinder, for Mars' atmospheric temperatures measured within about 1.3 m from the surface, assuming a power law dependence, and have found that these gradients superficially resemble those reported for the upper region of the terrestrial stable boundary layer.

  11. SLS Pathfinder Segments Car Train Departure

    NASA Image and Video Library

    2016-03-02

    An Iowa Northern locomotive, contracted by Goodloe Transportation of Chicago, travels along the NASA railroad bridge over the Indian River north of Kennedy Space Center, carrying one of two containers on a railcar for transport to the NASA Jay Jay railroad yard. The containers held two pathfinders, or test versions, of solid rocket booster segments for NASA’s Space Launch System rocket that were delivered to the Rotation, Processing and Surge Facility (RPSF). Inside the RPSF, the Ground Systems Development and Operations Program and Jacobs Engineering, on the Test and Operations Support Contract, will conduct a series of lifts, moves and stacking operations using the booster segments, which are inert, to prepare for Exploration Mission-1, deep-space missions and the journey to Mars. The pathfinder booster segments are from Orbital ATK in Utah.

  12. SLS Pathfinder Segments Car Train Departure

    NASA Image and Video Library

    2016-03-02

    An Iowa Northern locomotive, conracted by Goodloe Transportation of Chicago, travels along the NASA railroad bridge over the Indian River north of Kennedy Space Center, with two containers on railcars for transport to the NASA Jay Jay railroad yard. The containers held two pathfinders, or test versions, of solid rocket booster segments for NASA’s Space Launch System rocket that were delivered to the Rotation, Processing and Surge Facility (RPSF). Inside the RPSF, the Ground Systems Development and Operations Program and Jacobs Engineering, on the Test and Operations Support Contract, will conduct a series of lifts, moves and stacking operations using the booster segments, which are inert, to prepare for Exploration Mission-1, deep-space missions and the journey to Mars. The pathfinder booster segments are from Orbital ATK in Utah.

  13. SLS Pathfinder Segments Car Train Departure

    NASA Image and Video Library

    2016-03-02

    An Iowa Northern locomotive, contracted by Goodloe Transportation of Chicago, continues along the NASA railroad bridge over the Indian River north of Kennedy Space Center, carrying one of two containers on a railcar for transport to the NASA Jay Jay railroad yard. The containers held two pathfinders, or test versions, of solid rocket booster segments for NASA’s Space Launch System rocket that were delivered to the Rotation, Processing and Surge Facility (RPSF). Inside the RPSF, the Ground Systems Development and Operations Program and Jacobs Engineering, on the Test and Operations Support Contract, will conduct a series of lifts, moves and stacking operations using the booster segments, which are inert, to prepare for Exploration Mission-1, deep-space missions and the journey to Mars. The pathfinder booster segments are from Orbital ATK in Utah.

  14. SLS Pathfinder Segments Car Train Departure

    NASA Image and Video Library

    2016-03-02

    An Iowa Northern locomotive, contracted by Goodloe Transportation of Chicago, departs from the Rotation, Processing and Surge Facility (RPSF) at NASA’s Kennedy Space Center in Florida, with two containers on railcars for transport to the NASA Jay Jay railroad yard. The containers held two pathfinders, or test versions, of solid rocket booster segments for NASA’s Space Launch System rocket that were delivered to the RPSF. Inside the RPSF, the Ground Systems Development and Operations Program and Jacobs Engineering, on the Test and Operations Support Contract, will conduct a series of lifts, moves and stacking operations using the booster segments, which are inert, to prepare for Exploration Mission-1, deep-space missions and the journey to Mars. The pathfinder booster segments are from Orbital ATK in Utah.

  15. Big-Data Perspective to Operating an SKA-Type Synthesis Array Radio Telescope

    NASA Astrophysics Data System (ADS)

    Shanmugha Sundaram, GA

    2015-08-01

    Of the two forerunner sites, viz. Australia and South Africa, where pioneering advancements to state-of-the-art in synthesis array radio astronomy instrumentation are being attempted in the form of pathfinders to the Square Kilometer Array (SKA), for its eventual deployment, a diversity of site-dependent topology and design metrics exists. Towards addressing some of the fundamental mysteries in physics at the micro- and macro-cosm levels, that form the Key Science Projects (KSPs) for the SKA, and interfacing them to an optimally designed array conguration, a critical evaluation of their radio imaging capabilities and metrics becomes paramount. Here, the various KSPs and instrument design specifications are discussed, for relative merits and adaptability to either site, from invoking well-founded and established array-design and optimization principles designed into a customized software tool. Since the problem of array design is one that encompasses variables on several scales such as separation distances between the radio interferometric pair (termed the baseline), factors such as redundancy, flux and phase calibration, bandwidth, integration time, clock synchronization for the correlation process at the detector, and many other ambient-defined parameters, there is a significant component of big data involved in the complex visibilities that are to be Fourier transformed from the spatial to the radio-sky domain (to generate a radio sky map) using vast computational infrastructure, with robust data connectivity and data handling facilities to support this. A crucial requirement exists to make the general public aware of the implications of such a massive scale scientific and technological venture, which shall be the focus of this presentation.

  16. Reduction and Analysis of Meteorology Data from the Mars Pathfinder Lander

    NASA Technical Reports Server (NTRS)

    Murphy, James R.; Bridger, Alison F. C.; Haberle, Robert M.

    1998-01-01

    Dr. James Murphy is a member of the Mars Pathfinder Atmospheric Structure Investigation Meteorology (ASI/MET) Science Team. The activities of Dr. Murphy, and his collaborators are summarized in this report, which reviews the activities in support of the analysis of the meteorology data from the Mars Pathfinder Lander.

  17. Pathfinder Sea Surface Temperature Climate Data Record

    NASA Astrophysics Data System (ADS)

    Baker-Yeboah, S.; Saha, K.; Zhang, D.; Casey, K. S.

    2016-02-01

    Global sea surface temperature (SST) fields are important in understanding ocean and climate variability. The NOAA National Centers for Environmental Information (NCEI) develops and maintains a high resolution, long-term, climate data record (CDR) of global satellite SST. These SST values are generated at approximately 4 km resolution using Advanced Very High Resolution Radiometer (AVHRR) instruments aboard NOAA polar-orbiting satellites going back to 1981. The Pathfinder SST algorithm is based on the Non-Linear SST algorithm using the modernized NASA SeaWiFS Data Analysis System (SeaDAS). Coefficients for this SST product were generated using regression analyses with co-located in situ and satellite measurements. Previous versions of Pathfinder included level 3 collated (L3C) products. Pathfinder Version 5.3 includes level 2 pre-processed (L2P), level 3 Uncollated (L3C), and L3C products. Notably, the data were processed in the cloud using Amazon Web Services and are made available through all of the modern web visualization and subset services provided by the THREDDS Data Server, the Live Access Server, and the OPeNDAP Hyrax Server.In this version of Pathfinder SST, anomalous hot-spots at land-water boundaries are better identified and the dataset includes updated land masks and sea ice data over the Antarctic ice shelves. All quality levels of SST values are generated, giving the user greater flexibility and the option to apply their own cloud-masking procedures. Additional improvements include consistent cloud tree tests for NOAA-07 and NOAA-19 with respect to the other sensors, improved SSTs in sun glint areas, and netCDF file format improvements to ensure consistency with the latest Group for High Resolution SST (GHRSST) requirements. This quality controlled satellite SST field is a reference environmental data record utilized as a primary resource of SST for numerous regional and global marine efforts.

  18. Pathfinder Teaching and Learning Units.

    ERIC Educational Resources Information Center

    Hawaii Univ., Honolulu. Sea Grant Program.

    This collection of teaching units were selected from materials developed during the Operation Pathfinder Institutes (OPI) which took place in the Pacific region between 1994 and 1999. The institutes were intended to provide upper elementary and middle school science teachers with an opportunity to develop a deeper understanding of the marine…

  19. Relating MBSE to Spacecraft Development: A NASA Pathfinder

    NASA Technical Reports Server (NTRS)

    Othon, Bill

    2016-01-01

    The NASA Engineering and Safety Center (NESC) has sponsored a Pathfinder Study to investigate how Model Based Systems Engineering (MBSE) and Model Based Engineering (MBE) techniques can be applied by NASA spacecraft development projects. The objectives of this Pathfinder Study included analyzing both the products of the modeling activity, as well as the process and tool chain through which the spacecraft design activities are executed. Several aspects of MBSE methodology and process were explored. Adoption and consistent use of the MBSE methodology within an existing development environment can be difficult. The Pathfinder Team evaluated the possibility that an "MBSE Template" could be developed as both a teaching tool as well as a baseline from which future NASA projects could leverage. Elements of this template include spacecraft system component libraries, data dictionaries and ontology specifications, as well as software services that do work on the models themselves. The Pathfinder Study also evaluated the tool chain aspects of development. Two chains were considered: 1. The Development tool chain, through which SysML model development was performed and controlled, and 2. The Analysis tool chain, through which both static and dynamic system analysis is performed. Of particular interest was the ability to exchange data between SysML and other engineering tools such as CAD and Dynamic Simulation tools. For this study, the team selected a Mars Lander vehicle as the element to be designed. The paper will discuss what system models were developed, how data was captured and exchanged, and what analyses were conducted.

  20. Generation of auroral kilometric radiation and the structure of auroral acceleration region

    NASA Technical Reports Server (NTRS)

    Lee, L. C.; Kan, J. R.; Wu, C. S.

    1980-01-01

    Generation of auroral kilometric radiation (AKR) in the auroral acceleration region is studied. It is shown that auroral kilometric radiation can be generated by backscattered electrons trapped in the acceleration region via a cyclotron maser process. The parallel electric field in the acceleration region is required to be distributed over 1-2 earth radii. The observed AKR frequency spectrum can be used to estimate the altitude range of the auroral acceleration region. The altitudes of the lower and upper boundaries of the acceleration region determined from the AKR data are respectively approximately 2000 and 9000 km.

  1. SLS Pathfinder Segments Car Train Departure

    NASA Image and Video Library

    2016-03-02

    An Iowa Northern locomotive, contracted by Goodloe Transportation of Chicago, approaches the raised span of the NASA railroad bridge to continue over the Indian River north of Kennedy Space Center with two containers on railcars for storage at the NASA Jay Jay railroad yard. The containers held two pathfinders, or test versions, of solid rocket booster segments for NASA’s Space Launch System rocket that were delivered to the Rotation, Processing and Surge Facility (RPSF). Inside the RPSF, the Ground Systems Development and Operations Program and Jacobs Engineering, on the Test and Operations Support Contract, will conduct a series of lifts, moves and stacking operations using the booster segments, which are inert, to prepare for Exploration Mission-1, deep-space missions and the journey to Mars. The pathfinder booster segments are from Orbital ATK in Utah.

  2. SLS Pathfinder Segments Car Train Departure

    NASA Image and Video Library

    2016-03-02

    An Iowa Northern locomotive, contracted by Goodloe Transportation of Chicago, travels along the NASA railroad bridge over the Indian River north of Kennedy Space Center, carrying one of two containers on a railcar for transport to the NASA Jay Jay railroad yard near the center. The containers held two pathfinders, or test versions, of solid rocket booster segments for NASA’s Space Launch System rocket that were delivered to the Rotation, Processing and Surge Facility (RPSF). Inside the RPSF, the Ground Systems Development and Operations Program and Jacobs Engineering, on the Test and Operations Support Contract, will conduct a series of lifts, moves and stacking operations using the booster segments, which are inert, to prepare for Exploration Mission-1, deep-space missions and the journey to Mars. The pathfinder booster segments are from Orbital ATK in Utah.

  3. Design Overview of the DM Radio Pathfinder Experiment

    NASA Technical Reports Server (NTRS)

    Silva-Feaver, Maximiliano; Chaudhuri, Saptarshi; Cho, Hsaio-Mei; Dawson, Carl; Graham, Peter; Irwin, Kent; Kuenstner, Stephen; Li, Dale; Mardon, Jeremy; Moseley, Harvey; hide

    2016-01-01

    We introduce the DM Radio, a dual search for axion and hidden photon dark matter using a tunable superconducting lumped-element resonator. We discuss the prototype DM Radio Pathfinder experiment, which will probe hidden photons in the 500 peV (100 kHz)-50 neV (10 MHz) mass range. We detail the design of the various components: the LC resonant detector, the resonant frequency tuning procedure, the differential SQUID readout circuit, the shielding, and the cryogenic mounting structure. We present the current status of the pathfinder experiment and illustrate it's potential science reach in the context of the larger experimental program.

  4. Validation of the Version 1 NOAA/NASA Pathfinder Sea Surface Temperature Data Set

    NASA Technical Reports Server (NTRS)

    Smith, Elizabeth A.

    1998-01-01

    A high-resolution, global satellite-derived sea surface temperature (SST) data set called Pathfinder, from the Advanced Very High Resolution Radiometer (AVHRR) aboard the NOAA Polar Orbiters, is available from the Jet Propulsion Laboratory Physical Oceanography Distributed Active Archive Center (JPL PO.DAAC). Suitable for research as well as education, the Pathfinder SST data set is a result of a collaboration between the National Oceanographic and Atmospheric Administration (NOAA), the National Aeronautics and Space Administration (NASA) and investigators at several universities. NOAA and NASA are the sponsors of the Pathfinder Program, which takes advantage of currently archived Earth science data from satellites. Where necessary, satellite sensors have been intercalibrated, algorithms improved and processing procedures revised, in order to produce long time-series, global measurements of ocean, land and atmospheric properties necessary for climate research. Many Pathfinder data sets are available to researchers now, nearly a decade before the first launch of NASA's Earth Observing System (EOS). The lessons learned from the Pathfinder programs will facilitate the processing and management of terabytes of data from EOS. The Oceans component of Pathfinder has undertaken to reprocess all Global Area Coverage (GAC) data acquired by the 5-channel AVHRRs since 1981. The resultant data products are consistent and stably calibrated [Rao, 1993a, Rao, 1993b, Brown et al., 1993], Earth-gridded SST fields at a variety of spatial and temporal resolutions.

  5. Comparison of algorithms for determination of rotation measure and Faraday structure. I. 1100–1400 MHz

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

    Sun, X. H.; Akahori, Takuya; Anderson, C. S.

    2015-02-01

    Faraday rotation measures (RMs) and more general Faraday structures are key parameters for studying cosmic magnetism and are also sensitive probes of faint ionized thermal gas. A definition of which derived quantities are required for various scientific studies is needed, as well as addressing the challenges in determining Faraday structures. A wide variety of algorithms has been proposed to reconstruct these structures. In preparation for the Polarization Sky Survey of the Universe's Magnetism (POSSUM) to be conducted with the Australian Square Kilometre Array Pathfinder and the ongoing Galactic Arecibo L-band Feeds Array Continuum Transit Survey (GALFACTS), we run a Faradaymore » structure determination data challenge to benchmark the currently available algorithms, including Faraday synthesis (previously called RM synthesis in the literature), wavelet, compressive sampling, and QU-fitting. The input models include sources with one Faraday thin component, two Faraday thin components, and one Faraday thick component. The frequency set is similar to POSSUM/GALFACTS with a 300 MHz bandwidth from 1.1 to 1.4 GHz. We define three figures of merit motivated by the underlying science: (1) an average RM weighted by polarized intensity, RM{sub wtd}, (2) the separation Δϕ of two Faraday components, and (3) the reduced chi-squared χ{sub r}{sup 2}. Based on the current test data with a signal-to-noise ratio of about 32, we find the following. (1) When only one Faraday thin component is present, most methods perform as expected, with occasional failures where two components are incorrectly found. (2) For two Faraday thin components, QU-fitting routines perform the best, with errors close to the theoretical ones for RM{sub wtd} but with significantly higher errors for Δϕ. All other methods, including standard Faraday synthesis, frequently identify only one component when Δϕ is below or near the width of the Faraday point-spread function. (3) No methods as currently

  6. Pathfinder aircraft liftoff on altitude record setting flight of 71,500 feet

    NASA Image and Video Library

    1997-07-07

    The Pathfinder aircraft has set a new unofficial world record for high-altitude flight of over 71,500 feet for solar-powered aircraft at the U.S. Navy's Pacific Missile Range Facility, Kauai, Hawaii. Pathfinder was designed and manufactured by AeroVironment, Inc, of Simi Valley, California, and was operated by the firm under a jointly sponsored research agreement with NASA's Dryden Flight Research Center, Edwards, California. Pathfinder's record-breaking flight occurred July 7, 1997. The aircraft took off at 11:34 a.m. PDT, passed its previous record altitude of 67,350 feet at about 5:45 p.m. and then reached its new record altitude at 7 p.m. The mission ended with a perfect nighttime landing at 2:05 a.m. PDT July 8. The new record is the highest altitude ever attained by a propellor-driven aircraft. Before Pathfinder, the altitude record for propellor-driven aircraft was 67,028 feet, set by the experimental Boeing Condor remotely piloted aircraft.

  7. Powering the future - a new generation of high-performance solar arrays

    NASA Astrophysics Data System (ADS)

    Geyer, Freddy; Caswell, Doug; Signorini, Carla

    2007-08-01

    Funded by ESA's Advanced Research in Telecommunication (ARTES) programme, Thales Alenia Space has developed a new generation of high-power ultra-lightweight solar arrays for telecommunications satellites. Thanks to close cooperation with its industrial partners in Europe, the company has generically qualified a solar array io meet market needs. Indeed, three flight projects were already using the new design as qualification was completed. In addition, the excellent mechanical and thermal behaviour of the new panel structure are contributing to other missions such as Pleïades and LISA Pathfinder.

  8. LISA Pathfinder: An important first step towards a space-based gravitational wave observatory

    NASA Astrophysics Data System (ADS)

    Thorpe, James

    2017-08-01

    ESA's LISA Pathfinder mission was launched on Dec 3rd, 2015 and completed earlier this Summer. During this relatively short mission, Pathfinder at its two science payloads, Europe's LISA Technology Package and NASA's Disturbance Reduction System, demonstrated several techniques and technologies that enable development of a future space-based gravitational wave observatory. Most notably, Pathfinder demonstrated that the technique of drag-free flight could be utilized to place a test mass in near-perfect free-fall, with residual accelerations at the femto-g level in the milliHertz band. Additionally, technologies such as precision bonded optical structures for metrology, micropropulsion systems, and non-contact charge control, were successfully tested, retiring risk for LISA. In this talk, I will present an overview of Pathfinder's results to date and some perspective on how this success will be leveraged into realizing LISA.

  9. MARS PATHFINDER INSPECTED BY ENGINEER LINDA ROBECK IN SAEF-2

    NASA Technical Reports Server (NTRS)

    1996-01-01

    In the SAEF-2 spacecraft checkout facility, engineer Linda Robeck of the Jet Propulsion Laboratory inspects the Mars Pathfinder lander. The spacecraft arrived at Kennedy Space Center from Pasadena, CA on Aug. 13, 1996. The petals of the lander will be opened for checkout of the spacecraft and the installation of the small rover. Launch of Mars Pathfinder aboard a McDonnell Douglas Delta II rocket will occur from Pad B at Complex 17 on Dec. 2.

  10. Modeling to Mars: a NASA Model Based Systems Engineering Pathfinder Effort

    NASA Technical Reports Server (NTRS)

    Phojanamongkolkij, Nipa; Lee, Kristopher A.; Miller, Scott T.; Vorndran, Kenneth A.; Vaden, Karl R.; Ross, Eric P.; Powell, Bobby C.; Moses, Robert W.

    2017-01-01

    The NASA Engineering Safety Center (NESC) Systems Engineering (SE) Technical Discipline Team (TDT) initiated the Model Based Systems Engineering (MBSE) Pathfinder effort in FY16. The goals and objectives of the MBSE Pathfinder include developing and advancing MBSE capability across NASA, applying MBSE to real NASA issues, and capturing issues and opportunities surrounding MBSE. The Pathfinder effort consisted of four teams, with each team addressing a particular focus area. This paper focuses on Pathfinder team 1 with the focus area of architectures and mission campaigns. These efforts covered the timeframe of February 2016 through September 2016. The team was comprised of eight team members from seven NASA Centers (Glenn Research Center, Langley Research Center, Ames Research Center, Goddard Space Flight Center IV&V Facility, Johnson Space Center, Marshall Space Flight Center, and Stennis Space Center). Collectively, the team had varying levels of knowledge, skills and expertise in systems engineering and MBSE. The team applied their existing and newly acquired system modeling knowledge and expertise to develop modeling products for a campaign (Program) of crew and cargo missions (Projects) to establish a human presence on Mars utilizing In-Situ Resource Utilization (ISRU). Pathfinder team 1 developed a subset of modeling products that are required for a Program System Requirement Review (SRR)/System Design Review (SDR) and Project Mission Concept Review (MCR)/SRR as defined in NASA Procedural Requirements. Additionally, Team 1 was able to perform and demonstrate some trades and constraint analyses. At the end of these efforts, over twenty lessons learned and recommended next steps have been identified.

  11. Detection of Micrometeoroids with LISA Pathfinder

    NASA Astrophysics Data System (ADS)

    Thorpe, Ira; Littenberg, Tyson; Janchez, Diego; Baker, John; The LISA Pathfinder Team Team

    2017-01-01

    The LISA Pathfinder mission (LPF), a joint ESA/NASA technology demonstration mission currently operating at the Sun-Earth L1 point, contains the most precise accelerometry system ever flown. Analysis suggests that LPF should have sufficient sensitivity to detect impacts of small micrometeoroids and dust through their transfer of momentum to the spacecraft. Moreover, LPF's ability to fully resolve both the linear and angular momentum transfer in three dimensions allows a magnitude, direction, and location to be estimated for each impact. We present preliminary results from a systematic search of the LISA Pathfinder data for such impacts and discuss the prospects for using these and future results to inform models of the formation and evolution of dust populations in the inner solar system. These models have wide applicability to both pure and applied space science, ranging from the physics of planet formation and dynamics of minor Solar System bodies to estimates of the micrometeorite hazard for future spacecraft. 2017 NASA Science Innovation Fund.

  12. LISA Pathfinder first results

    NASA Astrophysics Data System (ADS)

    Vetrugno, D.

    LISA Pathfinder (LPF) is an in-flight technological demonstrator designed and launched to prove the feasibility of sub-femto-g free fall of kilo-sized test masses (TM), an essential ingredient for the future gravitational wave observatory from space. Half a year after launch, the first results are available and show an incredibly well-performing instrument. The results represent a first and important step towards the long awaited construction and launch of LISA, the Laser Interferometer Space Antenna.

  13. Research on Wide-field Imaging Technologies for Low-frequency Radio Array

    NASA Astrophysics Data System (ADS)

    Lao, B. Q.; An, T.; Chen, X.; Wu, X. C.; Lu, Y.

    2017-09-01

    Wide-field imaging of low-frequency radio telescopes are subject to a number of difficult problems. One particularly pernicious problem is the non-coplanar baseline effect. It will lead to distortion of the final image when the phase of w direction called w-term is ignored. The image degradation effects are amplified for telescopes with the wide field of view. This paper summarizes and analyzes several w-term correction methods and their technical principles. Their advantages and disadvantages have been analyzed after comparing their computational cost and computational complexity. We conduct simulations with two of these methods, faceting and w-projection, based on the configuration of the first-phase Square Kilometre Array (SKA) low frequency array. The resulted images are also compared with the two-dimensional Fourier transform method. The results show that image quality and correctness derived from both faceting and w-projection are better than the two-dimensional Fourier transform method in wide-field imaging. The image quality and run time affected by the number of facets and w steps have been evaluated. The results indicate that the number of facets and w steps must be reasonable. Finally, we analyze the effect of data size on the run time of faceting and w-projection. The results show that faceting and w-projection need to be optimized before the massive amounts of data processing. The research of the present paper initiates the analysis of wide-field imaging techniques and their application in the existing and future low-frequency array, and fosters the application and promotion to much broader fields.

  14. The Ilgarijiri Project: A collaboration between Aboriginal communities and radio astronomers in the Murchison Region of Western Australia

    NASA Astrophysics Data System (ADS)

    Goldsmith, John

    2014-07-01

    The international radio astronomy initiative known as the Square Kilometre Array is a cutting-edge science project, aimed atdramatically expanding our vision and understanding of the Universe. The $2billion+ international project is being shared between Southern Africa and Australia. The Australian component, centred in the Murchison region of Western Australia, is based upon collaboration with Aboriginal communities. A collaborative project called "Ilgarijiri- Things Belonging to the Sky" shared scientific and Aboriginal knowledge of the night sky. Through a series of collaborative meetings and knowledge sharing, the Ilgarijiri project developed and showcased Aboriginal knowledge of the night sky, via an international touring Aboriginal art exhibition, in Australia, South Africa, the USA and Europe. The Aboriginal art exhibition presents Aboriginal stories relating to the night sky, which prominently feature the 'Seven Sisters' and the 'Emu', as well as the collaborative experience with radio astronomers. The success of the Ilgarijiri collaborative project is based upon several principles, which can help to inform and guide future cultural collaborative projects.

  15. Interface Generation and Compositional Verification in JavaPathfinder

    NASA Technical Reports Server (NTRS)

    Giannakopoulou, Dimitra; Pasareanu, Corina

    2009-01-01

    We present a novel algorithm for interface generation of software components. Given a component, our algorithm uses learning techniques to compute a permissive interface representing legal usage of the component. Unlike our previous work, this algorithm does not require knowledge about the component s environment. Furthermore, in contrast to other related approaches, our algorithm computes permissive interfaces even in the presence of non-determinism in the component. Our algorithm is implemented in the JavaPathfinder model checking framework for UML statechart components. We have also added support for automated assume-guarantee style compositional verification in JavaPathfinder, using component interfaces. We report on the application of the presented approach to the generation of interfaces for flight software components.

  16. Mars Pathfinder Microrover- Implementing a Low Cost Planetary Mission Experiment

    NASA Technical Reports Server (NTRS)

    Matijevic, J.

    1996-01-01

    The Mars Pathfinder Microrover Flight Experiment (MFEX) is a NASA Office of Space Access and Technology (OSAT) flight experiment which has been delivered and integrated with the Mars Pathfinder (MPF) lander and spacecraft system. The total cost of the MFEX mission, including all subsystem design and development, test, integration with the MPF lander and operations on Mars has been capped at $25 M??is paper discusses the process and the implementation scheme which has resulted in the development of this first Mars rover.

  17. Calibration of radio-astronomical data on the cloud. LOFAR, the pathway to SKA

    NASA Astrophysics Data System (ADS)

    Sabater, J.; Sánchez-Expósito, S.; Garrido, J.; Ruiz, J. E.; Best, P. N.; Verdes-Montenegro, L.

    2015-05-01

    The radio interferometer LOFAR (LOw Frequency ARray) is fully operational now. This Square Kilometre Array (SKA) pathfinder allows the observation of the sky at frequencies between 10 and 240 MHz, a relatively unexplored region of the spectrum. LOFAR is a software defined telescope: the data is mainly processed using specialized software running in common computing facilities. That means that the capabilities of the telescope are virtually defined by software and mainly limited by the available computing power. However, the quantity of data produced can quickly reach huge volumes (several Petabytes per day). After the correlation and pre-processing of the data in a dedicated cluster, the final dataset is handled to the user (typically several Terabytes). The calibration of these data requires a powerful computing facility in which the specific state of the art software under heavy continuous development can be easily installed and updated. That makes this case a perfect candidate for a cloud infrastructure which adds the advantages of an on demand, flexible solution. We present our approach to the calibration of LOFAR data using Ibercloud, the cloud infrastructure provided by Ibergrid. With the calibration work-flow adapted to the cloud, we can explore calibration strategies for the SKA and show how private or commercial cloud infrastructures (Ibercloud, Amazon EC2, Google Compute Engine, etc.) can help to solve the problems with big datasets that will be prevalent in the future of astronomy.

  18. THE FIRST VERY LONG BASELINE INTERFEROMETRIC SETI EXPERIMENT

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

    Rampadarath, H.; Morgan, J. S.; Tingay, S. J.

    2012-08-15

    The first Search for Extra-Terrestrial Intelligence (SETI) conducted with very long baseline interferometry (VLBI) is presented. By consideration of the basic principles of interferometry, we show that VLBI is efficient at discriminating between SETI signals and human generated radio frequency interference (RFI). The target for this study was the star Gliese 581, thought to have two planets within its habitable zone. On 2007 June 19, Gliese 581 was observed for 8 hr at 1230-1544 MHz with the Australian Long Baseline Array. The data set was searched for signals appearing on all interferometer baselines above five times the noise limit. Amore » total of 222 potential SETI signals were detected and by using automated data analysis techniques were ruled out as originating from the Gliese 581 system. From our results we place an upper limit of 7 MW Hz{sup -1} on the power output of any isotropic emitter located in the Gliese 581 system within this frequency range. This study shows that VLBI is ideal for targeted SETI including follow-up observations. The techniques presented are equally applicable to next-generation interferometers, such as the long baselines of the Square Kilometre Array.« less

  19. Pathfinders: An Intellectual Guide to Libraries.

    ERIC Educational Resources Information Center

    Jung, Claudia Ruediger; And Others

    Intended as an example for other college libraries, this collection of 38 pathfinders and bibliographies was developed by the reference staff of the Calvin Coolidge Library at Castleton State College, Vermont. Designed to present the types of literature available in particular subject fields and those works readily available in the Coolidge…

  20. Pathfinders on Black Dance in America.

    ERIC Educational Resources Information Center

    Roy, Loriene, Ed.

    This is a compilation of 18 pathfinders (i.e., a bibliographic instruction aid) on black dance in America, prepared by graduate students in the "Information Resources in the Humanities" and the "Information Resources in the Social Sciences" classes in the Graduate School of Library and Information Science at the University of…

  1. Pathfinder-Plus aircraft in flight

    NASA Technical Reports Server (NTRS)

    1998-01-01

    The Pathfinder-Plus solar-powered aircraft is shown taking off from a runway, then flying at low altitude over the ocean. The vehicle, which looks like a flying ruler, operates at low airspeed. Among the missions proposed for a solar-powered aircraft are communications relay, atmospheric studies, pipeline monitoring and gas leak detection, environmental monitoring using thermal and radar images, and disaster relief and monitoring.

  2. Disturbance Reduction System Thrusters Stabilize LISA Pathfinder

    NASA Image and Video Library

    2015-12-03

    The LISA Pathfinder spacecraft is on its way to space, having successfully launched from Kourou, French Guiana Dec. 3, 2015. On board is the state-of-the-art Disturbance Reduction System DRS, a thruster technology developed at NASA JPL.

  3. MARS PATHFINDER LANDER REMOVED FROM SHIPPING CONTAINER IN SAEF-2

    NASA Technical Reports Server (NTRS)

    1996-01-01

    In the SAEF-2 spacecraft checkout facility at Kennedy Space Center, engineers and technicians from Jet Propulsion Laboratory remove the Mars Pathfinder lander from its shipping container, still covered in protective wrapping. Pictured from L-R, Linda Robeck, Jerry Gutierrez, Lorraine Garcia, Chuck Foehlinger of JPL. The arrival of the spacecraft at KSC from Pasadena, CA occurred on Aug. 13, 1996. Launch of Mars Pathfinder aboard a McDonnell Douglas Delta II rocket will occur from Pad B at Complex 17 on Dec. 2.

  4. Laser modulator for LISA pathfinder

    NASA Astrophysics Data System (ADS)

    Voland, C.; Lund, G.; Coppoolse, W.; Crosby, P.; Stadler, M.; Kudielka, K.; Özkan, C.

    2017-11-01

    LISA Pathfinder is an ESA experiment to demonstrate the key technologies needed for the LISA mission to detect gravitational waves in space. The LISA Pathfinder spacecraft represents one arm of the LISA interferometer, containing an optical metrology system and two proof masses as inertial references for the drag-free control system. The LISA Pathfinder payload consists of two drag-free floating test masses located in the inertial sensors with their control electronics and an optical metrology subsystem. The optical metrology subsystem monitors the movement of both test masses relative to each other and to the spacecraft with very high sensitivity and resolution. This is achieved with a heterodyne Mach- Zehnder interferometer. This interferometer requires as input two coherent laser beams with a heterodyne frequency difference of a few kHz. To generate the two laser beams with a heterodyne frequency difference a Nd:YAG laser is used together with the Laser Modulator. The Nd:YAG laser generates a single coherent laser signal at a wavelength of 1064nm which is fibre coupled to the Laser Modulator. The Laser Modulator then generates the two optical beams with the required heterodyne frequency offset. In addition, the Laser Modulator is required to perform laser amplitude stabilization and optical path difference control for the two optical signals. The Laser Modulator consists of an optical unit - the LMU - and RF synthesiser, power amplification and control electronics. These electronics are all housed in the Laser Modulator Electronics (LME). The LMU has four primary functions: • Splitting of the input laser beam into two paths for later superposition in the interferometer. • Applying different frequency shifts to each of the beams. • Providing amplitude modulation control to each of the beams. • Providing active control of the optical path length difference between the two optical paths. The present paper describes the design and performance of the LMU

  5. AVHRR-Based Polar Pathfinder Products: Evaluation, Enhancement and Transition to MODIS

    NASA Technical Reports Server (NTRS)

    Fowler, Charles; Masalanik, James; Stone, Robert; Stroeve, Julienne; Emery, William

    2001-01-01

    The Advanced Very High Resolution Radiometer (AVHRR)-Based Polar Pathfinder (APP) products include calibrated AVHRR channel data, surface temperatures, albedo, satellite scan and solar geometries, and cloud mask, all composited into twice-per-day images, and daily averaged fields of sea ice motion, for regions poleward of 50 latitude. Our general goals under this grant: (1) Quantify the APP accuracy and sources of error by comparing Pathfinder products with field measurements; (2) Determine the consistency of mean fields and trends in comparison with longer time series of available station data and forecast model output; (3) Investigate the consistency of the products between the different AVHRR instruments over the 1982-present period of the NOAA program; and (4) Compare and annual cycle of the APP products with MODIS to establish a baseline for extending Pathfinder-type products into the new ESE period.

  6. Kilometric Continuum Radiation

    NASA Technical Reports Server (NTRS)

    Green, James L.; Boardsen, Scott

    2006-01-01

    Kilometric continuum (KC) is the high frequency component (approximately 100 kHz to approximately 800 kHz) of nonthermal continuum (NTC). Unlike the lower frequency portion of NTC (approximately 5 kHz to approximately 100 kHz) whose source is around the dawn sector, the source of KC occurs at all magnetic local times. The latitudinal beaming of KC as observed by GEOTAIL is, for most events, restricted to plus or minus 15 degrees magnetic latitude. KC has been observed during periods of both low and strong geomagnetic activity, with no significant correlation of wave intensity with K(sub p), index. However statistically the maximum observed frequency of KC emission tends to increase with K(sub p) index, the effect is more pronounced around solar maximum, but is also detected near solar minimum. There is strong evidence that the source region of KC is from the equatorial plasmapause during periods when a portion of the plasmapause moves significantly inwards from its nominal position. Case studies have shown that KC emissions are nearly always associated with plasmaspheric notches, shoulders, and tails. There is a recent focus on trying to understand the banded frequency structure of this emission and its relationship to plasmaspheric density ducts and irregularities in the source region.

  7. Modis, SeaWIFS, and Pathfinder funded activities

    NASA Technical Reports Server (NTRS)

    Evans, Robert H.

    1995-01-01

    MODIS (Moderate Resolution Imaging Spectrometer), SeaWIFS (Sea-viewing Wide Field Sensor), Pathfinder, and DSP (Digital Signal Processor) objectives are summarized. An overview of current progress is given for the automatic processing database, client/server status, matchup database, and DSP support.

  8. Sub-Femto-g Free Fall for Space-Based Gravitational Wave Observatories: LISA Pathfinder Results.

    PubMed

    Armano, M; Audley, H; Auger, G; Baird, J T; Bassan, M; Binetruy, P; Born, M; Bortoluzzi, D; Brandt, N; Caleno, M; Carbone, L; Cavalleri, A; Cesarini, A; Ciani, G; Congedo, G; Cruise, A M; Danzmann, K; de Deus Silva, M; De Rosa, R; Diaz-Aguiló, M; Di Fiore, L; Diepholz, I; Dixon, G; Dolesi, R; Dunbar, N; Ferraioli, L; Ferroni, V; Fichter, W; Fitzsimons, E D; Flatscher, R; Freschi, M; García Marín, A F; García Marirrodriga, C; Gerndt, R; Gesa, L; Gibert, F; Giardini, D; Giusteri, R; Guzmán, F; Grado, A; Grimani, C; Grynagier, A; Grzymisch, J; Harrison, I; Heinzel, G; Hewitson, M; Hollington, D; Hoyland, D; Hueller, M; Inchauspé, H; Jennrich, O; Jetzer, P; Johann, U; Johlander, B; Karnesis, N; Kaune, B; Korsakova, N; Killow, C J; Lobo, J A; Lloro, I; Liu, L; López-Zaragoza, J P; Maarschalkerweerd, R; Mance, D; Martín, V; Martin-Polo, L; Martino, J; Martin-Porqueras, F; Madden, S; Mateos, I; McNamara, P W; Mendes, J; Mendes, L; Monsky, A; Nicolodi, D; Nofrarias, M; Paczkowski, S; Perreur-Lloyd, M; Petiteau, A; Pivato, P; Plagnol, E; Prat, P; Ragnit, U; Raïs, B; Ramos-Castro, J; Reiche, J; Robertson, D I; Rozemeijer, H; Rivas, F; Russano, G; Sanjuán, J; Sarra, P; Schleicher, A; Shaul, D; Slutsky, J; Sopuerta, C F; Stanga, R; Steier, F; Sumner, T; Texier, D; Thorpe, J I; Trenkel, C; Tröbs, M; Tu, H B; Vetrugno, D; Vitale, S; Wand, V; Wanner, G; Ward, H; Warren, C; Wass, P J; Wealthy, D; Weber, W J; Wissel, L; Wittchen, A; Zambotti, A; Zanoni, C; Ziegler, T; Zweifel, P

    2016-06-10

    We report the first results of the LISA Pathfinder in-flight experiment. The results demonstrate that two free-falling reference test masses, such as those needed for a space-based gravitational wave observatory like LISA, can be put in free fall with a relative acceleration noise with a square root of the power spectral density of 5.2±0.1  fm s^{-2}/sqrt[Hz], or (0.54±0.01)×10^{-15}  g/sqrt[Hz], with g the standard gravity, for frequencies between 0.7 and 20 mHz. This value is lower than the LISA Pathfinder requirement by more than a factor 5 and within a factor 1.25 of the requirement for the LISA mission, and is compatible with Brownian noise from viscous damping due to the residual gas surrounding the test masses. Above 60 mHz the acceleration noise is dominated by interferometer displacement readout noise at a level of (34.8±0.3)  fm/sqrt[Hz], about 2 orders of magnitude better than requirements. At f≤0.5  mHz we observe a low-frequency tail that stays below 12  fm s^{-2}/sqrt[Hz] down to 0.1 mHz. This performance would allow for a space-based gravitational wave observatory with a sensitivity close to what was originally foreseen for LISA.

  9. Pathfinder operations

    NASA Technical Reports Server (NTRS)

    Wilcher, J.; Stelzried, C.; Finley, S.

    1986-01-01

    In 1981, the Inter-Agency Consultative Group (composed of European, Soviet, Japanese and American space agency representatives) conceived the idea of using the two Soviet Vega spacecraft as pathfinders for Giotto since they would arrive at Halley's Comet approximately one week before Giotto. The Vega trajectory data and the Halley camera angle data were combined to improve the comet orbit accuracy. This was used to improve the Giotto fly-by targeting. The DSN performed delta DOR (VLBI) and one-way Doppler measurements of the Vega spacecraft for orbit determination. Although the early part-up phase had many problems, the results during the critical November 30, 1985 to March 4, 1986 operational phase had an overall 95 percent success rate, with 59 successes out of 62 two-station passes.

  10. High frame rate imaging system for limited diffraction array beam imaging with square-wave aperture weightings.

    PubMed

    Lu, Jian-Yu; Cheng, Jiqi; Wang, Jing

    2006-10-01

    A general-purpose high frame rate (HFR) medical imaging system has been developed. This system has 128 independent linear transmitters, each of which is capable of producing an arbitrary broadband (about 0.05-10 MHz) waveform of up to +/- 144 V peak voltage on a 75-ohm resistive load using a 12-bit/40-MHz digital-to-analog converter. The system also has 128 independent, broadband (about 0.25-10 MHz), and time-variable-gain receiver channels, each of which has a 12-bit/40-MHz analog-to-digital converter and up to 512 MB of memory. The system is controlled by a personal computer (PC), and radio frequency echo data of each channel are transferred to the same PC via a standard USB 2.0 port for image reconstructions. Using the HFR imaging system, we have developed a new limited-diffraction array beam imaging method with square-wave aperture voltage weightings. With this method, in principle, only one or two transmitters are required to excite a fully populated two-dimensional (2-D) array transducer to achieve an equivalent dynamic focusing in both transmission and reception to reconstruct a high-quality three-dimensional image without the need of the time delays of traditional beam focusing and steering, potentially simplifying the transmitter subsystem of an imager. To validate the method, for simplicity, 2-D imaging experiments were performed using the system. In the in vitro experiment, a custom-made, 128-element, 0.32-mm pitch, 3.5-MHz center frequency linear array transducer with about 50% fractional bandwidth was used to reconstruct images of an ATS 539 tissue-mimicking phantom at an axial distance of 130 mm with a field of view of more than 90 degrees. In the in vivo experiment of a human heart, images with a field of view of more than 90 degrees at 120-mm axial distance were obtained with a 128-element, 2.5-MHz center frequency, 0.15-mm pitch Acuson V2 phased array. To ensure that the system was operated under the limits set by the U.S. Food and Drug

  11. Immersive Environments for Mission Operations: Beyond Mars Pathfinder

    NASA Technical Reports Server (NTRS)

    Wright, J.; Hartman, F.; Cooper, B.

    1998-01-01

    Immersive environments are just beginning to be used to support mission operations at the Jet Propulsion Laboratory. This technology contributed to the Mars Pathfinder Mission in planning sorties for the Sojourner rover.

  12. Rationale for a Mars Pathfinder mission to Chryse Planitia and the Viking 1 lander

    NASA Technical Reports Server (NTRS)

    Craddock, Robert A.

    1994-01-01

    Presently the landing site for Mars Pathfinder will be constrained to latitudes between 0 deg and 30 deg N to facilitate communication with earth and to allow the lander and rover solar arrays to generate the maximum possible power. The reference elevation of the site must also be below 0 km so that the descent parachute, a Viking derivative, has sufficient time to open and slow the lander to the correct terminal velocity. Although Mars has as much land surface area as the continental crust of the earth, such engineering constraints immediately limit the number of possible landing sites to only three broad areas: Amazonis, Chryse, and Isidis Planitia. Of these, both Chryse and Isidis Planitia stand out as the sites offering the most information to address several broad scientific topics.

  13. Gambling on the Protestants: the Pathfinder Fund and birth control in Peru, 1958-1965.

    PubMed

    López, L Necochea

    2014-01-01

    Among the agencies involved in population control activities in the mid-twentieth century, none scored as many early victories in Latin America as did the Pathfinder Fund, founded by Procter & Gamble scion Clarence Gamble. This article analyzes a style in the delivery of family planning assistance in the developing world through the work of the Pathfinder Fund in Peru, the organization's hub in South America, and shows how Pathfinder personnel collaborated with local Protestant institutions. Its Protestant allies helped Pathfinder set up and manage rapid interventions such as the production of pamphlets, the smuggling of contraceptives, and the enrollment of physicians as advocates of the use of intrauterine devices. Although these rapid interventions helped quickly disseminate information and certain technologies among a fortunate few, they also weakened legitimate state agencies, neglected the monitoring of the safety of the drugs supplied, and alienated allies with their high-handed boldness.

  14. A Census of Southern Pulsars at 185 MHz

    NASA Astrophysics Data System (ADS)

    Xue, Mengyao; Bhat, N. D. R.; Tremblay, S. E.; Ord, S. M.; Sobey, C.; Swainston, N. A.; Kaplan, D. L.; Johnston, Simon; Meyers, B. W.; McSweeney, S. J.

    2017-12-01

    The Murchison Widefield Array, and its recently developed Voltage Capture System, facilitates extending the low-frequency range of pulsar observations at high-time and -frequency resolution in the Southern Hemisphere, providing further information about pulsars and the ISM. We present the results of an initial time-resolved census of known pulsars using the Murchison Widefield Array. To significantly reduce the processing load, we incoherently sum the detected powers from the 128 Murchison Widefield Array tiles, which yields 10% of the attainable sensitivity of the coherent sum. This preserves the large field-of-view ( 450 deg2 at 185 MHz), allowing multiple pulsars to be observed simultaneously. We developed a WIde-field Pulsar Pipeline that processes the data from each observation and automatically folds every known pulsar located within the beam. We have detected 50 pulsars to date, 6 of which are millisecond pulsars. This is consistent with our expectation, given the telescope sensitivity and the sky coverage of the processed data ( 17 000 deg2). For 10 pulsars, we present the lowest frequency detections published. For a subset of the pulsars, we present multi-frequency pulse profiles by combining our data with published profiles from other telescopes. Since the Murchison Widefield Array is a low-frequency precursor to the Square Kilometre Array, we use our census results to forecast that a survey using the low-frequency component of the Square Kilometre Array Phase 1 can potentially detect around 9 400 pulsars.

  15. Saturation and energy-conversion efficiency of auroral kilometric radiation

    NASA Technical Reports Server (NTRS)

    Wu, C. S.; Tsai, S. T.; Xu, M. J.; Shen, J. W.

    1981-01-01

    A quasi-linear theory is used to study the saturation level of the auroral kilometric radiation. The investigation is based on the assumption that the emission is due to a cyclotron maser instability as suggested by Wu and Lee and Lee et al. The thermodynamic bound on the radiation energy is also estimated separately. The energy-conversion efficiency of the radiation process is discussed. The results are consistent with observations.

  16. Operations and Autonomy of the Mars Pathfinder Microrover

    NASA Technical Reports Server (NTRS)

    Mishkin, A. H.; Morrison, J. C.; Nguyen, T. T.; Stone, H. W.; Cooper, B. K.

    1998-01-01

    The Microrover Flight Experiment (MFEX) is a NSAS OACT (Office of Advanced Concepts and Technology) flight experiment which, integrated with the Mars Pathfinder (MPF) lander and spacecraft system, landed on Mars on July 4, 1997.

  17. Pathfinder on lakebed rolling out for test flight

    NASA Image and Video Library

    1995-12-10

    The Pathfinder research aircraft's wing structure is clearly defined in this photo as personnel from AeroVironment rolled it out onto the lakebed at NASA's Dryden Flight Research Center, Edwards, California, for another test flight.

  18. Square-core bundles for astronomical imaging

    NASA Astrophysics Data System (ADS)

    Bryant, Julia J.; Bland-Hawthorn, Joss

    2012-09-01

    Optical fibre imaging bundles (hexabundles) are proving to be the next logical step for large galaxy surveys as they offer spatially-resolved spectroscopy of galaxies and can be used with conventional fibre positioners. Hexabundles have been effectively demonstrated in the Sydney-AAO Multi-object IFS (SAMI) instrument at the Anglo- Australian Telescope[5]. Based on the success of hexabundles that have circular cores, we have characterised a bundle made instead from square-core fibres. Square cores naturally pack more evenly, which reduces the interstitial holes and can increase the covering, or filling fraction. Furthermore the regular packing simplifies the process of combining and dithering the final images. We discuss the relative issues of filling fraction, focal ratio degradation (FRD), and cross-talk, and find that square-core bundles perform well enough to warrant further development as a format for imaging fibre bundles.

  19. Mineralogic and compositional properties of Martian soil and dust: results from Mars Pathfinder

    USGS Publications Warehouse

    Bell, J.F.; McSween, H.Y.; Crisp, J.A.; Morris, R.V.; Murchie, S.L.; Bridges, N.T.; Johnson, J. R.; Britt, D.T.; Golombek, M.P.; Moore, H.J.; Ghosh, A.; Bishop, J.L.; Anderson, R.C.; Brückner, J.; Economou, T.; Greenwood, J.P.; Gunnlaugsson, H.P.; Hargraves, R.M.; Hviid, S.; Knudsen, J.M.; Madsen, M.B.; Reid, R.; Rieder, R.; Soderblom, L.

    2000-01-01

    Mars Pathfinder obtained multispectral, elemental, magnetic, and physical measurements of soil and dust at the Sagan Memorial Station during the course of its 83 sol mission. We describe initial results from these measurements, concentrating on multispectral and elemental data, and use these data, along with previous Viking, SNC meteorite, and telescopic results, to help constrain the origin and evolution of Martian soil and dust. We find that soils and dust can be divided into at least eight distinct spectral units, based on parameterization of Imager for Mars Pathfinder (IMP) 400 to 1000 nm multispectral images. The most distinctive spectral parameters for soils and dust are the reflectivity in the red, the red/blue reflectivity ratio, the near-IR spectral slope, and the strength of the 800 to 1000 nm absorption feature. Most of the Pathfinder spectra are consistent with the presence of poorly crystalline or nanophase ferric oxide(s), sometimes mixed with small but varying degrees of well-crystalline ferric and ferrous phases. Darker soil units appear to be coarser-grained, compacted, and/or mixed with a larger amount of dark ferrous materials relative to bright soils. Nanophase goethite, akaganeite, schwertmannite, and maghemite are leading candidates for the origin of the absorption centered near 900 nm in IMP spectra. The ferrous component in the soil cannot be well-constrained based on IMP data. Alpha proton X-ray spectrometer (APXS) measurements of six soil units show little variability within the landing site and show remarkable overall similarity to the average Viking-derived soil elemental composition. Differences exist between Viking and Pathfinder soils, however, including significantly higher S and Cl abundances and lower Si abundances in Viking soils and the lack of a correlation between Ti and Fe in Pathfinder soils. No significant linear correlations were observed between IMP spectral properties and APXS elemental chemistry. Attempts at constraining

  20. Rock Abrasion on Mars: Clues from the Pathfinder and Viking Landing Sites

    NASA Technical Reports Server (NTRS)

    Bridges, N. T.; Parker, T. J.; Kramer, G. M.

    2000-01-01

    A significant discovery of the Mars Pathfinder (MPF) mission was that many rocks exhibit characteristics of ventifacts, rocks that have been sculpted by saltating particles. Diagnostic features identifying the rocks as ventifacts am elongated pits, flutes, and grooves (collectively referred to as "flutes" unless noted otherwise). Faceted rocks or rock portions, circular pits, rills, and possibly polished rock surfaces are also seen and could be due, to aeolian abrasion. Many of these features were initially identified in rover images, where spatial resolution generally exceeded that of the IMP (Imager for Mars Pathfinder) camera. These images had two major limitations: 1) Only a limited number of rocks were viewed by the rover, biasing flute statistics; and 2) The higher resolution obtained by the rover images and the lack of such pictures at the Viking landing sites hampered comparisons of rock morphologies between the Pathfinder and Viking sites. To avoid this problem, rock morphology and ventifact statistics have been examined using new "super-resolution" IMP and Viking Lander images. Analyses of these images show that: 1) Flutes are seen on about 50% or more of the rocks in the near field at the MPF site; 2) The orientation of these flutes is similar to that for flutes identified in rover images; and 3) Ventifacts are significantly more abundant at the Pathfinder landing site than at the two Viking Landing sites, where rocks have undergone only a limited amount of aeolian abrasion. This is most likely due to the ruggedness of the Pathfinder site and a greater supply of abrading particles available shortly after the Arcs and Tiu Valles outflow channel floods.

  1. Radio telescope search for the resonant conversion of cold dark matter axions from the magnetized astrophysical sources

    NASA Astrophysics Data System (ADS)

    Huang, Fa Peng; Kadota, Kenji; Sekiguchi, Toyokazu; Tashiro, Hiroyuki

    2018-06-01

    We study the conditions for the adiabatic resonant conversion of the cold dark matter (CDM) axions into photons in the astrophysically sourced strong magnetic fields such as those in the neutron star magnetosphere. We demonstrate the possibility that the forthcoming radio telescopes such as the SKA (Square Kilometre Array) can probe those photon signals from the CDM axions.

  2. Jupiter's atmospheric jet streams extend thousands of kilometres deep.

    PubMed

    Kaspi, Y; Galanti, E; Hubbard, W B; Stevenson, D J; Bolton, S J; Iess, L; Guillot, T; Bloxham, J; Connerney, J E P; Cao, H; Durante, D; Folkner, W M; Helled, R; Ingersoll, A P; Levin, S M; Lunine, J I; Miguel, Y; Militzer, B; Parisi, M; Wahl, S M

    2018-03-07

    The depth to which Jupiter's observed east-west jet streams extend has been a long-standing question. Resolving this puzzle has been a primary goal for the Juno spacecraft, which has been in orbit around the gas giant since July 2016. Juno's gravitational measurements have revealed that Jupiter's gravitational field is north-south asymmetric, which is a signature of the planet's atmospheric and interior flows. Here we report that the measured odd gravitational harmonics J 3 , J 5 , J 7 and J 9 indicate that the observed jet streams, as they appear at the cloud level, extend down to depths of thousands of kilometres beneath the cloud level, probably to the region of magnetic dissipation at a depth of about 3,000  kilometres. By inverting the measured gravity values into a wind field, we calculate the most likely vertical profile of the deep atmospheric and interior flow, and the latitudinal dependence of its depth. Furthermore, the even gravity harmonics J 8 and J 10 resulting from this flow profile also match the measurements, when taking into account the contribution of the interior structure. These results indicate that the mass of the dynamical atmosphere is about one per cent of Jupiter's total mass.

  3. Survey parameters for detecting 21cm - Lyα emitter cross correlations with the Square Kilometre Array

    NASA Astrophysics Data System (ADS)

    Hutter, Anne; Trott, Cathryn M.; Dayal, Pratika

    2018-06-01

    Detections of the cross correlation signal between the 21cm signal during reionization and high-redshift Lyman Alpha emitters (LAEs) are subject to observational uncertainties which mainly include systematics associated with radio interferometers and LAE selection. These uncertainties can be reduced by increasing the survey volume and/or the survey luminosity limit, i.e. the faintest detectable Lyman Alpha (Lyα) luminosity. We use our model of high-redshift LAEs and the underlying reionization state to compute the uncertainties of the 21cm-LAE cross correlation function at z ≃ 6.6 for observations with SKA1-Low and LAE surveys with Δz = 0.1 for three different values of the average IGM ionization state (⟨χHI⟩≃ 0.1, 0.25, 0.5). At z ≃ 6.6, we find SILVERRUSH type surveys, with a field of view of 21 deg2 and survey luminosity limits of Lα ≥ 7.9 × 1042erg s-1, to be optimal to distinguish between an inter-galactic medium (IGM) that is 50%, 25% and 10% neutral, while surveys with smaller fields of view and lower survey luminosity limits, such as the 5 and 10 deg2 surveys with WFIRST, can only discriminate between a 50% and 10% neutral IGM.

  4. H I observations of the nearest starburst galaxy NGC 253 with the SKA precursor KAT-7

    NASA Astrophysics Data System (ADS)

    Lucero, D. M.; Carignan, C.; Elson, E. C.; Randriamampandry, T. H.; Jarrett, T. H.; Oosterloo, T. A.; Heald, G. H.

    2015-07-01

    We present H I observations of the Sculptor group starburst spiral galaxy NGC 253, obtained with the Karoo Array Telescope (KAT-7). KAT-7 is a pathfinder for the Square Kilometre Array precursor MeerKAT, under construction. The short baselines and low system temperature of the telescope make it very sensitive to large-scale, low-surface-brightness emission. The KAT-7 observations detected 33 per cent more flux than previous Very Large Array observations, mainly in the outer parts and in the halo for a total H I mass of 2.1 ± 0.1 × 109 M⊙. H I can be found at large distances perpendicular to the plane out to projected distances of ˜9-10 kpc away from the nucleus and ˜13-14 kpc at the edge of the disc. A novel technique, based on interactive profile fitting, was used to separate the main disc gas from the anomalous (halo) gas. The rotation curve (RC) derived for the H I disc confirms that it is declining in the outer parts, as seen in previous optical Fabry-Perot measurements. As for the anomalous component, its RC has a very shallow gradient in the inner parts and turns over at the same radius as the disc, kinematically lagging by 100 km s-1. The kinematics of the observed extra-planar gas is compatible with an outflow due to the central starburst and galactic fountains in the outer parts. However, the gas kinematics shows no evidence for inflow. Analysis of the near-IR WISE data, shows clearly that the star formation rate is compatible with the starburst nature of NGC 253.

  5. Preliminary Findings of the Photovoltaic Cell Calibration Experiment on Pathfinder Flight 95-3

    NASA Technical Reports Server (NTRS)

    Vargas-Aburto, Carlos

    1997-01-01

    The objective of the photovoltaic (PV) cell calibration experiment for Pathfinder was to develop an experiment compatible with an ultralight UAV to predict the performance of PV cells at AM0, the solar spectrum in space, using the Langley plot technique. The Langley plot is a valuable technique for this purpose and requires accurate measurements of air mass (pressure), cell temperature, solar irradiance, and current-voltage(IV) characteristics with the cells directed normal to the direct ray of the sun. Pathfinder's mission objective (95-3) of 65,000 ft. maximum altitude, is ideal for performing the Langley plot measurements. Miniaturization of electronic data acquisition equipment enabled the design and construction of an accurate and light weight measurement system that meets Pathfinder's low payload weight requirements.

  6. The stimulation of auroral kilometric radiation by type III solar radio bursts

    NASA Technical Reports Server (NTRS)

    Calvert, W.

    1981-01-01

    It has been found that the onset of auroral kilometric radiation (AKR) frequently coincides with the arrival of type III solar radio bursts. Although the AKR onsets are usually abrupt and appear to be spontaneous, they sometimes develop from a discrete frequency near the leading edge of a type III burst or sometimes occur at progressively lower frequencies following that edge. From this, and the absence of the related solar electrons in specific cases, it was concluded that the incoming type III waves were sometimes responsible for stimulating auroral kilometric radiation. It was estimated that intense, isolated type III bursts were capable of stimulating AKR roughly one third of the time, and that at least ten percent of the observed AKR onsets could be attributed to these and weaker bursts, including some barely detectable by the ISEE plasma wave receivers.

  7. Multi-element array signal reconstruction with adaptive least-squares algorithms

    NASA Technical Reports Server (NTRS)

    Kumar, R.

    1992-01-01

    Two versions of the adaptive least-squares algorithm are presented for combining signals from multiple feeds placed in the focal plane of a mechanical antenna whose reflector surface is distorted due to various deformations. Coherent signal combining techniques based on the adaptive least-squares algorithm are examined for nearly optimally and adaptively combining the outputs of the feeds. The performance of the two versions is evaluated by simulations. It is demonstrated for the example considered that both of the adaptive least-squares algorithms are capable of offsetting most of the loss in the antenna gain incurred due to reflector surface deformations.

  8. Dark Energy and Gravity Experiment Explorer and Pathfinder

    NASA Astrophysics Data System (ADS)

    Chiow, S.-w.; Yu, N.

    2018-02-01

    We propose to utilize the unique gravity and vacuum environment in the orbits of the Deep Space Gateway for direct detections of dark energy using atom interferometers, and for pathfinder experiments for future gravitational wave and dark matter detections.

  9. Design of the MESUR/pathfinder microrover

    NASA Technical Reports Server (NTRS)

    Stone, Henry W.

    1994-01-01

    The use of unmanned robotic vehicles to assist in the exploration of Mars and other planets has been of interest to the National Aeronautics and Space Administration (NASA) for several decades and has been the focus of an ongoing research program at the Jet Propulsion Laboratory (JPL) for a similar period of time. As a result of these research activities, JPL is in the process of designing and building a small (7-9 kg) microrover to be flown aboard the Mars Environmental Survey Mission (MESUR)/Pathfinder spacecraft, which is tentatively to be launched to Mars in late 1997. The microrover will perform a variety of technology experiments designed to provide information critical to the design of future planetary rovers. In addition, the microrover will perform several science and lander related experiments using specialized onboard instruments. To enable the microrover to perform these experiments at selected target areas and at the same time deal with the long time delays (and limited communications bandwidth), a control/navigation approach combining the use of operator-designated waypoints and onboard behavior control has been adopted. The design of the MESUR/Pathfinder microrover and the overall manner in which it is controlled are described herein.

  10. Motoneuron axon pathfinding errors in zebrafish: Differential effects related to concentration and timing of nicotine exposure

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

    Menelaou, Evdokia; Paul, Latoya T.; Perera, Surangi N.

    Nicotine exposure during embryonic stages of development can affect many neurodevelopmental processes. In the developing zebrafish, exposure to nicotine was reported to cause axonal pathfinding errors in the later born secondary motoneurons (SMNs). These alterations in SMN axon morphology coincided with muscle degeneration at high nicotine concentrations (15–30 μM). Previous work showed that the paralytic mutant zebrafish known as sofa potato exhibited nicotine-induced effects onto SMN axons at these high concentrations but in the absence of any muscle deficits, indicating that pathfinding errors could occur independent of muscle effects. In this study, we used varying concentrations of nicotine at differentmore » developmental windows of exposure to specifically isolate its effects onto subpopulations of motoneuron axons. We found that nicotine exposure can affect SMN axon morphology in a dose-dependent manner. At low concentrations of nicotine, SMN axons exhibited pathfinding errors, in the absence of any nicotine-induced muscle abnormalities. Moreover, the nicotine exposure paradigms used affected the 3 subpopulations of SMN axons differently, but the dorsal projecting SMN axons were primarily affected. We then identified morphologically distinct pathfinding errors that best described the nicotine-induced effects on dorsal projecting SMN axons. To test whether SMN pathfinding was potentially influenced by alterations in the early born primary motoneuron (PMN), we performed dual labeling studies, where both PMN and SMN axons were simultaneously labeled with antibodies. We show that only a subset of the SMN axon pathfinding errors coincided with abnormal PMN axonal targeting in nicotine-exposed zebrafish. We conclude that nicotine exposure can exert differential effects depending on the levels of nicotine and developmental exposure window. - Highlights: • Embryonic nicotine exposure can specifically affect secondary motoneuron axons in a dose

  11. Mechanical design of the Mars Pathfinder mission

    NASA Technical Reports Server (NTRS)

    Eisen, Howard Jay; Buck, Carl W.; Gillis-Smith, Greg R.; Umland, Jeffrey W.

    1997-01-01

    The Mars Pathfinder mission and the Sojourner rover is reported on, with emphasis on the various mission steps and the performance of the technologies involved. The mechanical design of mission hardware was critical to the success of the entry sequence and the landing operations. The various mechanisms employed are considered.

  12. Delta II Mars Pathfinder

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Final preparations for lift off of the DELTA II Mars Pathfinder Rocket are shown. Activities include loading the liquid oxygen, completing the construction of the Rover, and placing the Rover into the Lander. After the countdown, important visual events include the launch of the Delta Rocket, burnout and separation of the three Solid Rocket Boosters, and the main engine cutoff. The cutoff of the main engine marks the beginning of the second stage engine. After the completion of the second stage, the third stage engine ignites and then cuts off. Once the third stage engine cuts off spacecraft separation occurs.

  13. Mars Pathfinder mission operations concepts

    NASA Technical Reports Server (NTRS)

    Sturms, Francis M., Jr.; Dias, William C.; Nakata, Albert Y.; Tai, Wallace S.

    1994-01-01

    The Mars Pathfinder Project plans a December 1996 launch of a single spacecraft. After jettisoning a cruise stage, an entry body containing a lander and microrover will directly enter the Mars atmosphere and parachute to a hard landing near the sub-solar latitude of 15 degrees North in July 1997. Primary surface operations last for 30 days. Cost estimates for Pathfinder ground systems development and operations are not only lower in absolute dollars, but also are a lower percentage of total project costs than in past planetary missions. Operations teams will be smaller and fewer than typical flight projects. Operations scenarios have been developed early in the project and are being used to guide operations implementation and flight system design. Recovery of key engineering data from entry, descent, and landing is a top mission priority. These data will be recorded for playback after landing. Real-time tracking of a modified carrier signal through this phase can provide important insight into the spacecraft performance during entry, descent, and landing in the event recorded data is never recovered. Surface scenarios are dominated by microrover activity and lander imaging during 7 hours of the Mars day from 0700 to 1400 local solar time. Efficient uplink and downlink processes have been designed to command the lander and microrover each Mars day.

  14. Northeast View From Pathfinder Lander

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This panorama of the region to the northeast of the lander was constructed to support the Sojourner Rover Team's plans to conduct an 'autonomous traverse' to explore the terrain away from the lander after science objectives in the lander vicinity had been met. The large, relatively bright surface in the foreground, about 10 meters (33 feet) from the spacecraft, in this scene is 'Baker's Bench.' The large, elongated rock left of center in the middle distance is 'Zaphod.'

    This view was produced by combining 8 individual 'Superpan' scenes from the left and right eyes of the IMP camera. Each frame consists of 8 individual frames (left eye) and 7 frames (right eye) taken with different color filters that were enlarged by 500% and then co-added using Adobe Photoshop to produce, in effect, a super-resolution panchromatic frame that is sharper than an individual frame would be.

    Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology (Caltech). The IMP was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.

  15. PATHFINDER: Probing Atmospheric Flows in an Integrated and Distributed Environment

    NASA Technical Reports Server (NTRS)

    Wilhelmson, R. B.; Wojtowicz, D. P.; Shaw, C.; Hagedorn, J.; Koch, S.

    1995-01-01

    PATHFINDER is a software effort to create a flexible, modular, collaborative, and distributed environment for studying atmospheric, astrophysical, and other fluid flows in the evolving networked metacomputer environment of the 1990s. It uses existing software, such as HDF (Hierarchical Data Format), DTM (Data Transfer Mechanism), GEMPAK (General Meteorological Package), AVS, SGI Explorer, and Inventor to provide the researcher with the ability to harness the latest in desktop to teraflop computing. Software modules developed during the project are available in the public domain via anonymous FTP from the National Center for Supercomputing Applications (NCSA). The address is ftp.ncsa.uiuc.edu, and the directory is /SGI/PATHFINDER.

  16. NASA's Webb "Pathfinder Telescope" Successfully Completes First Super-Cold Optical Test

    NASA Image and Video Library

    2017-12-08

    Testing is crucial part of NASA's success on Earth and in space. So, as the actual flight components of NASA's James Webb Space Telescope come together, engineers are testing the non-flight equipment to ensure that tests on the real Webb telescope later goes safely and according to plan. Recently, the "pathfinder telescope," or just “Pathfinder,” completed its first super-cold optical test that resulted in many first-of-a-kind demonstrations. "This test is the first dry-run of the equipment and procedures we will use to conduct an end-to-end optical test of the flight telescope and instruments," said Mark Clampin, Webb telescope Observatory Project Scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "It provides confidence that once the flight telescope is ready, we are fully prepared for a successful test of the flight hardware." The Pathfinder is a non-flight replica of the Webb telescope’s center section backplane, or “backbone,” that includes mirrors. The flight backplane comes in three segments, a center section and two wing-like parts, all of which will support large hexagonal mirrors on the Webb telescope. The pathfinder only consists of the center part of the backplane. However, during the test, it held two full size spare primary mirror segments and a full size spare secondary mirror to demonstrate the ability to optically test and align the telescope at the planned operating temperatures of -400 degrees Fahrenheit (-240 Celsius). Read more: www.nasa.gov/feature/goddard/nasas-webb-pathfinder-telesc... Credit: NASA/Goddard/Chris Gunn NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

  17. Sojourner Rover View of Pathfinder Lander

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Image of Pathfinder Lander on Mars taken from Sojourner Rover left front camera on sol 33. The IMP (on the lattice mast) is looking at the rover. Airbags are prominent, and the meteorology mast is shown to the right. Lowermost rock is Ender, with Hassock behind it and Yogi on the other side of the lander.

    NOTE: original caption as published in Science Magazine

  18. Characterization of a 2 × 2 array of large square bars of LaBr3:Ce detectors with γ-rays up to 22.5 MeV

    NASA Astrophysics Data System (ADS)

    Dhibar, M.; Mazumdar, I.; Chavan, P. B.; Patel, S. M.; Anil Kumar, G.

    2018-03-01

    LaBr3:Ce scintillators have recently become commercially available in sizes large enough for measurements of high energy gamma-rays. In this communication, we report our studies on properties and response of large volume square bars (2‧‧ ×2‧‧ ×8‧‧) of LaBr3:Ce detectors, individually, and in a compact array of four square bars, with gamma-rays up to 22.5 MeV. The properties studied are, uniformity of the crystal, internal radioactivity, energy resolution, timing resolution, linearity of the response and detection efficiencies. The response of the detectors for 22.5 MeV γ-rays produced from 11B(p , γ)12C capture reaction and for 15.1 MeV γ-rays produced from 12C(p ,p‧ γ)12C inelastic scattering reaction are studied in detail. The measured absolute efficiencies (both total detection and photo-peak) for 662 keV gamma-rays from 137Cs are compared to those obtained using realistic GEANT4 simulations. The primary aim of the array is to measure high energy gamma-rays (5-50 MeV) produced from the de-excitation of excited Giant Dipole Resonance (GDR) states, radiative capture reactions, nuclear Bremsstrahlung process and inelastic scattering process. The highly satisfactory performance of the array provides the impetus for future efforts toward building a bigger array.

  19. A Fast Radio Burst Every Second?

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2017-09-01

    far. [Fialkov Loeb 2017]The FRB luminosity functionFRBs may all have the same intrinsic brightness (like Type Ia supernovae, for instance). Alternatively, there may be many more faint and dim FRBs than bright ones (like the distribution of galaxy luminosities). Thisdifference affects the number of FRBs we could detect.The host galaxy populationAre FRBs most commonly hosted by low-mass galaxies like FRB 121102? Or do they occur in high-mass galaxies as well? This affects the number of FRBs we would expect to observe at different redshifts.Future HopeBy exploring a range of models that vary these three factors, Fialkov and Loeb find estimates for the rate of FRBs that would appear inthe 500 MHz3.5 GHz frequency band probed by observatories like Parkes, Arecibo, and the Australian Square Kilometre Array Pathfinder (ASKAP).Fialkov and Loeb find that, when we account for faint sources, one FRB may occur per second across the sky in this band. The authors show that future low-frequency radio telescopes with higher sensitivity, such as the Square Kilometre Array, should be able to detect many more of these sources, helping us to differentiate between the models and narrow down the properties of the bursts and their hosts. This, in turn, may finally reveal what causes these mysterious signals.CitationAnastasia Fialkov and Abraham Loeb 2017 ApJL 846 L27. doi:10.3847/2041-8213/aa8905

  20. Uncoupling nicotine mediated motoneuron axonal pathfinding errors and muscle degeneration in zebrafish

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

    Welsh, Lillian; Tanguay, Robert L.; Svoboda, Kurt R.

    Zebrafish embryos offer a unique opportunity to investigate the mechanisms by which nicotine exposure impacts early vertebrate development. Embryos exposed to nicotine become functionally paralyzed by 42 hpf suggesting that the neuromuscular system is compromised in exposed embryos. We previously demonstrated that secondary spinal motoneurons in nicotine-exposed embryos were delayed in development and that their axons made pathfinding errors (Svoboda, K.R., Vijayaraghaven, S., Tanguay, R.L., 2002. Nicotinic receptors mediate changes in spinal motoneuron development and axonal pathfinding in embryonic zebrafish exposed to nicotine. J. Neurosci. 22, 10731-10741). In that study, we did not consider the potential role that altered skeletalmore » muscle development caused by nicotine exposure could play in contributing to the errors in spinal motoneuron axon pathfinding. In this study, we show that an alteration in skeletal muscle development occurs in tandem with alterations in spinal motoneuron development upon exposure to nicotine. The alteration in the muscle involves the binding of nicotine to the muscle-specific AChRs. The nicotine-induced alteration in muscle development does not occur in the zebrafish mutant (sofa potato, [sop]), which lacks muscle-specific AChRs. Even though muscle development is unaffected by nicotine exposure in sop mutants, motoneuron axonal pathfinding errors still occur in these mutants, indicating a direct effect of nicotine exposure on nervous system development.« less

  1. Visible and Near-Infrared Properties of Optical Fibers Coupled to the Pathfinder High-Resolution NIR Spectrograph

    NASA Astrophysics Data System (ADS)

    McCoy, K.; Ramsey, L.

    2011-09-01

    The Penn State Astronomy and Astrophysics Department’s Pathfinder instrument is a fiber-fed, warm-bench echelle spectrograph designed to explore technical issues that must be resolved in order to measure precise radial velocities that will allow the detection of exoplanets in the near-infrared (NIR). In May 2010, Pathfinder demonstrated 10-20 m/s radial-velocity precision in the NIR at the 9 meter Hobby-Eberly Telescope. To attain even higher precision, we are investigating the NIR properties of the optical fibers that transmit light from the telescope to Pathfinder. We conducted a series of modal noise tests with visible and NIR laser diodes on a 200 micron diameter, fused-silica, multimode optical fiber as the preliminary step in analyzing the degrading effects of modal noise on radial-velocity precision. We report these test results and comment on our future tests to reduce the negative effects of modal noise and focal ratio degradation (FRD). The lessons learned from this research and the Pathfinder prototype will be used in Pathfinder II, which will aim to achieve better than 5 m/s in the NIR.

  2. Lithium-Thionyl Chloride Batteries for the Mars Pathfinder Microrover

    NASA Technical Reports Server (NTRS)

    Deligiannis, Frank; Frank, Harvey; Staniewicz, R. J.; Willson, John

    1996-01-01

    A discussion of the power requirements for the Mars Pathfinder Mission is given. Topics include: battery requirements; cell design; battery design; test descriptions and results. A summary of the results is also included.

  3. Indoor A* Pathfinding Through an Octree Representation of a Point Cloud

    NASA Astrophysics Data System (ADS)

    Rodenberg, O. B. P. M.; Verbree, E.; Zlatanova, S.

    2016-10-01

    There is a growing demand of 3D indoor pathfinding applications. Researched in the field of robotics during the last decades of the 20th century, these methods focussed on 2D navigation. Nowadays we would like to have the ability to help people navigate inside buildings or send a drone inside a building when this is too dangerous for people. What these examples have in common is that an object with a certain geometry needs to find an optimal collision free path between a start and goal point. This paper presents a new workflow for pathfinding through an octree representation of a point cloud. We applied the following steps: 1) the point cloud is processed so it fits best in an octree; 2) during the octree generation the interior empty nodes are filtered and further processed; 3) for each interior empty node the distance to the closest occupied node directly under it is computed; 4) a network graph is computed for all empty nodes; 5) the A* pathfinding algorithm is conducted. This workflow takes into account the connectivity for each node to all possible neighbours (face, edge and vertex and all sizes). Besides, a collision avoidance system is pre-processed in two steps: first, the clearance of each empty node is computed, and then the maximal crossing value between two empty neighbouring nodes is computed. The clearance is used to select interior empty nodes of appropriate size and the maximal crossing value is used to filter the network graph. Finally, both these datasets are used in A* pathfinding.

  4. A design pathfinder with material correlation points for inflatable systems

    NASA Astrophysics Data System (ADS)

    Fulcher, Jared Terrell

    The incorporation of inflatable structures into aerospace systems can produce significant advantages in stowed volume to mechanical effectiveness and overall weight. Many applications of these ultra-lightweight systems are designed to precisely control internal or external surfaces, or both, to achieve desired performance. The modeling of these structures becomes complex due to the material nonlinearities inherent to the majority of construction materials used in inflatable structures. Furthermore, accurately modeling the response and behavior of the interfacing boundaries that are common to many inflatable systems will lead to better understanding of the entire class of structures. The research presented involved using nonlinear finite element simulations correlated with photogrammetry testing to develop a procedure for defining material properties for commercially available polyurethane-coated woven nylon fabric, which is representative of coated materials that have been proven materials for use in many inflatable systems. Further, the new material model was used to design and develop an inflatable pathfinder system which employs only internal pressure to control an assembly of internal membranes. This canonical inflatable system will be used for exploration and development of general understanding of efficient design methodology and analysis of future systems. Canonical structures are incorporated into the design of the phased pathfinder system to allow for more universal insight. Nonlinear finite element simulations were performed to evaluate the effect of various boundary conditions, loading configurations, and material orientations on the geometric precision of geometries representing typical internal/external surfaces commonly incorporated into inflatable pathfinder system. The response of the inflatable system to possible damage was also studied using nonlinear finite element simulations. Development of a correlated material model for analysis of the

  5. Analysis of Mars Pathfinder Entry Data, Aerothermal Heating, and Heat Shield Material Response

    NASA Technical Reports Server (NTRS)

    Milos, Frank; Chen, Y. K.; Tran, H. K.; Rasky, Daniel J. (Technical Monitor)

    1997-01-01

    The Mars Pathfinder heatshield contained several thermocouples and resistance thermometers. A description of the experiment, the entry data, and analysis of the entry environment and material response is presented. In particular, the analysis addresses uncertainties of the data and the fluid dynamics and material response models. The calculations use the latest trajectory and atmosphere reconstructions for the Pathfinder entry. A modified version of the GIANTS code is used for CFD (computational fluid dynamics) analyses, and FIAT is used for material response. The material response and flowfield are coupled appropriately. Three different material response models are considered. The analysis of Pathfinder entry data for validation of aerothermal heating and material response models is complicated by model uncertainties and unanticipated data-acquisition and processing problems. We will discuss these issues as well as ramifications of the data and analysis for future Mars missions.

  6. Photogrammetric analysis of horizon panoramas: The Pathfinder landing site in Viking orbiter images

    USGS Publications Warehouse

    Oberst, J.; Jaumann, R.; Zeitler, W.; Hauber, E.; Kuschel, M.; Parker, T.; Golombek, M.; Malin, M.; Soderblom, L.

    1999-01-01

    Tiepoint measurements, block adjustment techniques, and sunrise/sunset pictures were used to obtain precise pointing data with respect to north for a set of 33 IMP horizon images. Azimuth angles for five prominent topographic features seen at the horizon were measured and correlated with locations of these features in Viking orbiter images. Based on this analysis, the Pathfinder line/sample coordinates in two raw Viking images were determined with approximate errors of 1 pixel, or 40 m. Identification of the Pathfinder location in orbit imagery yields geological context for surface studies of the landing site. Furthermore, the precise determination of coordinates in images together with the known planet-fixed coordinates of the lander make the Pathfinder landing site the most important anchor point in current control point networks of Mars. Copyright 1999 by the American Geophysical Union.

  7. A Pathfinder for Animal Research and Animal Rights.

    ERIC Educational Resources Information Center

    Anderson, David C.

    1992-01-01

    This pathfinder was originally prepared for "Biomedical Research and Animal Rights," a session sponsored by the Veterinary Medical Libraries and Research Libraries Sections of the Medical Library Association. Current resources are described, from bibliographies to electronic bulletin boards, which relate to the issue of laboratory animal…

  8. ASKAP Joins the Hunt for Mysterious Bursts

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2017-05-01

    A new telescope, the Australian Square Kilometre Array Pathfinder (ASKAP), has joined the search for energetic and elusive fast radio bursts. And in just a few days of looking, its already had success!Elusive TransientsThe Parkes radio telescope, which has detected all but five of the fast radio bursts published to date, has a very narrow field of view. [CSIRO]Fast radio bursts are mysterious millisecond-duration radio pulses that were first discovered around a decade ago. Since that time particularly in recent years weve made some progress toward the goal of localizing them. Were now fairly convinced that fast radio bursts come from outside of the galaxy, and yet theyre enormously bright orders of magnitude more luminous than any pulse seen from the Milky Way.Better identification of where these mysterious bursts come from would help us to determine what they are. But so far, weve discovered only around 30 such bursts, despite the fact that theyre estimated to occur at a rate of 3,000 events per day across the whole sky.Why are they so hard to find? Due to their short duration, effective detection would require instantaneous coverage of a very large fraction of the sky. The Parkes radio telescope which has detected all but five of the fast radio bursts published to date has a field of view spanning less than a square degree,significantly limiting our ability to rapidly survey for these transients.FRB 170107s band-averaged pulse (top) and dynamic spectrum (bottom). [Bannister et al. 2017]A New Array in TownA new player is now on the scene, however, and its already had huge success. ASKAP is a wide-field radio telescope made up of an array of 12-meter antennas. Using phased-array-feed technology, ASKAP is able to instantaneously observe an effective area of 160 square degrees an enormous field compared to Parkes 0.6 square degrees! This capability significantly increases our chances of being able to detect fast radio bursts.In a new study led by Keith Bannister

  9. Jupiter’s atmospheric jet streams extend thousands of kilometres deep

    NASA Astrophysics Data System (ADS)

    Kaspi, Y.; Galanti, E.; Hubbard, W. B.; Stevenson, D. J.; Bolton, S. J.; Iess, L.; Guillot, T.; Bloxham, J.; Connerney, J. E. P.; Cao, H.; Durante, D.; Folkner, W. M.; Helled, R.; Ingersoll, A. P.; Levin, S. M.; Lunine, J. I.; Miguel, Y.; Militzer, B.; Parisi, M.; Wahl, S. M.

    2018-03-01

    The depth to which Jupiter’s observed east–west jet streams extend has been a long-standing question. Resolving this puzzle has been a primary goal for the Juno spacecraft, which has been in orbit around the gas giant since July 2016. Juno’s gravitational measurements have revealed that Jupiter’s gravitational field is north–south asymmetric, which is a signature of the planet’s atmospheric and interior flows. Here we report that the measured odd gravitational harmonics J3, J5, J7 and J9 indicate that the observed jet streams, as they appear at the cloud level, extend down to depths of thousands of kilometres beneath the cloud level, probably to the region of magnetic dissipation at a depth of about 3,000  kilometres. By inverting the measured gravity values into a wind field, we calculate the most likely vertical profile of the deep atmospheric and interior flow, and the latitudinal dependence of its depth. Furthermore, the even gravity harmonics J8 and J10 resulting from this flow profile also match the measurements, when taking into account the contribution of the interior structure. These results indicate that the mass of the dynamical atmosphere is about one per cent of Jupiter’s total mass.

  10. Extrapolation of in situ data from 1-km squares to adjacent squares using remote sensed imagery and airborne lidar data for the assessment of habitat diversity and extent.

    PubMed

    Lang, M; Vain, A; Bunce, R G H; Jongman, R H G; Raet, J; Sepp, K; Kuusemets, V; Kikas, T; Liba, N

    2015-03-01

    Habitat surveillance and subsequent monitoring at a national level is usually carried out by recording data from in situ sample sites located according to predefined strata. This paper describes the application of remote sensing to the extension of such field data recorded in 1-km squares to adjacent squares, in order to increase sample number without further field visits. Habitats were mapped in eight central squares in northeast Estonia in 2010 using a standardized recording procedure. Around one of the squares, a special study site was established which consisted of the central square and eight surrounding squares. A Landsat-7 Enhanced Thematic Mapper Plus (ETM+) image was used for correlation with in situ data. An airborne light detection and ranging (lidar) vegetation height map was also included in the classification. A series of tests were carried out by including the lidar data and contrasting analytical techniques, which are described in detail in the paper. Training accuracy in the central square varied from 75 to 100 %. In the extrapolation procedure to the surrounding squares, accuracy varied from 53.1 to 63.1 %, which improved by 10 % with the inclusion of lidar data. The reasons for this relatively low classification accuracy were mainly inherent variability in the spectral signatures of habitats but also differences between the dates of imagery acquisition and field sampling. Improvements could therefore be made by better synchronization of the field survey and image acquisition as well as by dividing general habitat categories (GHCs) into units which are more likely to have similar spectral signatures. However, the increase in the number of sample kilometre squares compensates for the loss of accuracy in the measurements of individual squares. The methodology can be applied in other studies as the procedures used are readily available.

  11. Sedimentary geomorphology of the Mars Pathfinder Landing Site

    NASA Technical Reports Server (NTRS)

    Rice, James W., Jr.; Parker, Timothy Jay

    1997-01-01

    The first landing on Mars in over 20 years will take place July 4, 1997, near te mouth of the Ares Vallis outflow channel located in southeastern Chryse Planitia. Mars Pathfinder, unlike Viking 1, is expected to land on a surface that has a distinct and unambiguous fluvial signature.

  12. Future X Pathfinder: Quick, Low Cost Flight Testing for Tomorrow's Launch Vehicles

    NASA Technical Reports Server (NTRS)

    London, John, III; Sumrall, Phil

    1999-01-01

    The DC-X and DC-XA Single Stage Technology flight program demonstrated the value of low cost rapid prototyping and flight testing of launch vehicle technology testbeds. NASA is continuing this important legacy through a program referred to as Future-X Pathfinder. This program is designed to field flight vehicle projects that cost around $100M each, with a new vehicle flying about every two years. Each vehicle project will develop and extensively flight test a launch vehicle technology testbed that will advance the state of the art in technologies directly relevant to future space transportation systems. There are currently two experimental, or "X" vehicle projects in the Pathfinder program, with additional projects expected to follow in the near future. The first Pathfinder project is X-34. X-34 is a suborbital rocket plane capable of flights to Mach 8 and 75 kilometers altitude. There are a number of reusable launch vehicle technologies embedded in the X-34 vehicle design, such as composite structures and propellant tanks, and advanced reusable thermal protection systems. In addition, X-34 is designed to carry experiments applicable to both the launch vehicle and hypersonic aeronautics community. X-34 is scheduled to fly later this year. The second Pathfinder project is the X-37. X-37 is an orbital space plane that is carried into orbit either by the Space Shuttle or by an expendable launch vehicle. X-37 provides NASA access to the orbital and orbital reentry flight regimes with an experimental testbed vehicle. The vehicle will expose embedded and carry-on advanced space transportation technologies to the extreme environments of orbit and reentry. Early atmospheric approach and landing tests of an unpowered version of the X-37 will begin next year, with orbital flights beginning in late 2001. Future-X Pathfinder is charting a course for the future with its growing fleet of low-cost X- vehicles. X-34 and X-37 are leading the assault on high launch costs and

  13. UP TO 100,000 RELIABLE STRONG GRAVITATIONAL LENSES IN FUTURE DARK ENERGY EXPERIMENTS

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

    Serjeant, S.

    2014-09-20

    The Euclid space telescope will observe ∼10{sup 5} strong galaxy-galaxy gravitational lens events in its wide field imaging survey over around half the sky, but identifying the gravitational lenses from their observed morphologies requires solving the difficult problem of reliably separating the lensed sources from contaminant populations, such as tidal tails, as well as presenting challenges for spectroscopic follow-up redshift campaigns. Here I present alternative selection techniques for strong gravitational lenses in both Euclid and the Square Kilometre Array, exploiting the strong magnification bias present in the steep end of the Hα luminosity function and the H I mass function.more » Around 10{sup 3} strong lensing events are detectable with this method in the Euclid wide survey. While only ∼1% of the total haul of Euclid lenses, this sample has ∼100% reliability, known source redshifts, high signal-to-noise, and a magnification-based selection independent of assumptions of lens morphology. With the proposed Square Kilometre Array dark energy survey, the numbers of reliable strong gravitational lenses with source redshifts can reach 10{sup 5}.« less

  14. Review of the trajectory and atmospheric structure reconstruction for Mars Pathfinder

    NASA Astrophysics Data System (ADS)

    Withers, Paul; Towner, Martin; Hathi, Brijen; Zarnecki, John

    2004-02-01

    Mars Pathfinder landed on Mars on July 4, 1997. It used a novel deceleration procedure, consisting of a hypersonic aeroshell, a transonic parachute, retro-rockets, and airbags, to reach the surface safely. Its aerodynamic properties passively maintained a near-zero angle of attack throughout its entry. There were no gyroscopes to monitor attitude. Several different trajectory reconstructions have been based on the assumptions that accelerations along its symmetry axis are directed along its flight path and that accelerations in other directions are insignificant. The aerodynamics of Pathfinder once its parachute opened are still not well-understood and the available observations are probably not sufficient to improve matters significantly in the future.

  15. Shielding in ungated field emitter arrays

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

    Harris, J. R.; Jensen, K. L.; Shiffler, D. A.

    Cathodes consisting of arrays of high aspect ratio field emitters are of great interest as sources of electron beams for vacuum electronic devices. The desire for high currents and current densities drives the cathode designer towards a denser array, but for ungated emitters, denser arrays also lead to increased shielding, in which the field enhancement factor β of each emitter is reduced due to the presence of the other emitters in the array. To facilitate the study of these arrays, we have developed a method for modeling high aspect ratio emitters using tapered dipole line charges. This method can bemore » used to investigate proximity effects from similar emitters an arbitrary distance away and is much less computationally demanding than competing simulation approaches. Here, we introduce this method and use it to study shielding as a function of array geometry. Emitters with aspect ratios of 10{sup 2}–10{sup 4} are modeled, and the shielding-induced reduction in β is considered as a function of tip-to-tip spacing for emitter pairs and for large arrays with triangular and square unit cells. Shielding is found to be negligible when the emitter spacing is greater than the emitter height for the two-emitter array, or about 2.5 times the emitter height in the large arrays, in agreement with previously published results. Because the onset of shielding occurs at virtually the same emitter spacing in the square and triangular arrays, the triangular array is preferred for its higher emitter density at a given emitter spacing. The primary contribution to shielding in large arrays is found to come from emitters within a distance of three times the unit cell spacing for both square and triangular arrays.« less

  16. Rock and Soil Types at Pathfinder Landing Site

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Type areas of rocks and soils. (A) Dark rock type and bright soil type: Shown is the dark rock Barnacle Bill. Reflectance spectra typical of fresh basalt and APXS spectra indicating more silica-rich basaltic andesite compositions characterize this type. These rocks are typically the small boulders and intermediate-sized cobbles at the Pathfinder site. The bright soil type is very common and in this case comprises Barnacle Bill's wind tail and much of the surround soil area. This soil has a high reflectance and a strongly reddened spectrum indicative of oxidized ferric minerals. (B) Bright rock type: Shown is the bright rock Wedge. Reflectance spectra typical of weathered basalt and APXS spectra indicating basaltic compositions characterize this type. These rocks are typically larger than 1 meter in diameter and many display morphologies indicating flood deposition. (C) Pink rock type: Shown is the pink rock Scooby Doo. APXS and reflectance spectra indicate a composition and optical characteristics similar to the drift soil. However, the morphology of the pink rock type indicates a cemented or rocklike structure. This material may be a chemically cemented hardpan that underlies much of the Pathfinder site. (D) Dark soil type: The dark soil type is typically found on the windward sides of rocks or in rock-free areas like Photometry Flats (shown here) where the bright soil has been striped away by aeolian action or in open areas. Other locations include the Mermaid Dune. (E) Disturbed soil type: The darkening of disturbed soil relative to its parent material, bright soil, as a result of changes in soil texture and compaction caused by movement of the rover and retraction of the lander airbag. (F) Lamb-like soil type: This soil type shows reflectance and spectral characteristics intermediate between the bright and dark soils. Its distinguishing feature is a weak spectral absorption near 900 nanometers not seen in either the bright or dark soils.

    NOTE: original

  17. Motoneuron axon pathfinding errors in zebrafish: Differential effects related to concentration and timing of nicotine exposure

    PubMed Central

    Menelaou, Evdokia; Paul, Latoya T.; Perera, Surangi N.; Svoboda, Kurt R.

    2015-01-01

    Nicotine exposure during embryonic stages of development can affect many neurodevelopmental processes. In the developing zebrafish, exposure to nicotine was reported to cause axonal pathfinding errors in the later born secondary motoneurons (SMN). These alterations in SMN axon morphology coincided with muscle degeneration at high nicotine concentrations (15–30µM). Previous work showed that the paralytic mutant zebrafish known as sofa potato, exhibited nicotine-induced effects onto SMN axons at these high concentrations but in the absence of any muscle deficits, indicating that pathfinding errors could occur independent of muscle effects. In this study, we used varying concentrations of nicotine at different developmental windows of exposure to specifically isolate its effects onto subpopulations of motoneuron axons. We found that nicotine exposure can affect SMN axon morphology in a dose-dependent manner. At low concentrations of nicotine, SMN axons exhibited pathfinding errors, in the absence of any nicotine-induced muscle abnormalities. Moreover, the nicotine exposure paradigms used affected the 3 subpopulations of SMN axons differently, but the dorsal projecting SMN axons were primarily affected. We then identified morphologically distinct pathfinding errors that best described the nicotine-induced effects on dorsal projecting SMN axons. To test whether SMN pathfinding was potentially influenced by alterations in the early born primary motoneuron (PMN), we performed dual labeling studies, where both PMN and SMN axons were simultaneously labeled with antibodies. We show that only a subset of the SMN axon pathfinding errors coincided with abnormal PMN axonal targeting in nicotine-exposed zebrafish. We conclude that nicotine exposure can exert differential effects depending on the levels of nicotine and developmental exposure window. PMID:25668718

  18. Atmosphere Processing Module Automation and Catalyst Durability Analysis for Mars ISRU Pathfinder

    NASA Technical Reports Server (NTRS)

    Petersen, Elspeth M.

    2016-01-01

    The Mars In-Situ Resource Utilization Pathfinder was designed to create fuel using components found in the planet’s atmosphere and regolith for an ascension vehicle to return a potential sample return or crew return vehicle from Mars. The Atmosphere Processing Module (APM), a subunit of the pathfinder, uses cryocoolers to isolate and collect carbon dioxide from Mars simulant gas. The carbon dioxide is fed with hydrogen into a Sabatier reactor where methane is produced. The APM is currently undergoing the final stages of testing at Kennedy Space Center prior to process integration testing with the other subunits of the pathfinder. The automation software for the APM cryocoolers was tested and found to perform nominally. The catalyst used for the Sabatier reactor was investigated to determine the factors contributing to catalyst failure. The results from the catalyst testing require further analysis, but it appears that the rapid change in temperature during reactor start up or the elevated operating temperature is responsible for the changes observed in the catalyst.

  19. Mars Pathfinder flight system integration and test.

    NASA Astrophysics Data System (ADS)

    Muirhead, B. K.

    This paper describes the system integration and test experiences, problems and lessons learned during the assembly, test and launch operations (ATLO) phase of the Mars Pathfinder flight system scheduled to land on the surface of Mars on July 4, 1997. The Mars Pathfinder spacecraft consists of three spacecraft systems: cruise stage, entry vehicle and lander. The cruise stage carries the entry and lander vehicles to Mars and is jettisoned prior to entry. The entry vehicle, including aeroshell, parachute and deceleration rockets, protects the lander during the direct entry and reduces its velocity from 7.6 to 0 km/s in stages during the 5 min entry sequence. The lander's touchdown is softened by airbags which are retracted once stopped on the surface. The lander then uprights itself, opens up fully and begins surface operations including deploying its camera and rover. This paper overviews the system design and the results of the system integration and test activities, including the entry, descent and landing subsystem elements. System test experiences including science instruments, the microrover, Sojourner, and software are discussed. The final qualification of the entry, descent and landing subsystems during this period is also discussed.

  20. Simultaneous Determination of Iron, Copper and Cobalt in Food Samples by CCD-diode Array Detection-Flow Injection Analysis with Partial Least Squares Calibration Model

    NASA Astrophysics Data System (ADS)

    Mi, Jiaping; Li, Yuanqian; Zhou, Xiaoli; Zheng, Bo; Zhou, Ying

    2006-01-01

    A flow injection-CCD diode array detection spectrophotometry with partial least squares (PLS) program for simultaneous determination of iron, copper and cobalt in food samples has been established. The method was based on the chromogenic reaction of the three metal ions and 2- (5-Bromo-2-pyridylazo)-5-diethylaminophenol, 5-Br-PADAP in acetic acid - sodium acetate buffer solution (pH5) with Triton X-100 and ascorbic acid. The overlapped spectra of the colored complexes were collected by charge-coupled device (CCD) - diode array detector and the multi-wavelength absorbance data was processed using partial least squares (PLS) algorithm. Optimum reaction conditions and parameters of flow injection analysis were investigated. The samples of tea, sesame, laver, millet, cornmeal, mung bean and soybean powder were determined by the proposed method. The average recoveries of spiked samples were 91.80%~100.9% for Iron, 92.50%~108.0% for Copper, 93.00%~110.5% for Cobalt, respectively with relative standard deviation (R.S.D) of 1.1%~12.1%. The sampling rate is 45 samples h-1. The determination results of the food samples were in good agreement between the proposed method and ICP-AES.

  1. Career pathfinders: a qualitative study of career development.

    PubMed

    Beutell, Icholas J; O'Hare, Marianne M

    2006-04-01

    This paper examined the perceptions of career path and issues of MBA students in response to Lore's The Pathfinder, a comprehensive career-planning model. Using internet discussion boards, an interactive dialogue was mentioned by participants in response to the components of Lore's model. The sample consisted of 50 fully employed MBA students enrolled in a course on self-assessment and career planning. A total of 1,781 separate postings were made and analyzed, using inductive analysis derived from discussion threads based on Lore's categories: comments on Lore's Pathfinder model, living a life you love (what's the holdup, career fantasies, work and family issues, and career selection), how to get there from here (commitment and future from the present), and designing your future career. Findings indicated several interesting trends in the career planning of current MBA students, particularly the importance of self or self-reflective observations in real time as students who are also fully employed formulate career plans. Implications for psychologists and career counselors, career development models, and suggestions for research are presented.

  2. AN OPPORTUNISTIC SEARCH FOR EXTRATERRESTRIAL INTELLIGENCE (SETI) WITH THE MURCHISON WIDEFIELD ARRAY

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

    Tingay, S. J.; Tremblay, C.; Walsh, A.

    A spectral line image cube generated from 115 minutes of MWA data that covers a field of view of 400 sq, deg. around the Galactic Center is used to perform the first Search for ExtraTerrestrial Intelligence (SETI) with the Murchison Widefield Array (MWA). Our work constitutes the first modern SETI experiment at low radio frequencies, here between 103 and 133 MHz, paving the way for large-scale searches with the MWA and, in the future, the low-frequency Square Kilometre Array. Limits of a few hundred mJy beam{sup −1} for narrowband emission (10 kHz) are derived from our data, across our 400more » sq. deg. field of view. Within this field, 45 exoplanets in 38 planetary systems are known. We extract spectra at the locations of these systems from our image cube to place limits on the presence of narrow line emission from these systems. We then derive minimum isotropic transmitter powers for these exoplanets; a small handful of the closest objects (10 s of pc) yield our best limits of order 10{sup 14} W (Equivalent Isotropic Radiated Power). These limits lie above the highest power directional transmitters near these frequencies currently operational on Earth. A SETI experiment with the MWA covering the full accessible sky and its full frequency range would require approximately one month of observing time. The MWA frequency range, its southern hemisphere location on an extraordinarily radio quiet site, its very large field of view, and its high sensitivity make it a unique facility for SETI.« less

  3. An Opportunistic Search for Extraterrestrial Intelligence (SETI) with the Murchison Widefield Array

    NASA Astrophysics Data System (ADS)

    Tingay, S. J.; Tremblay, C.; Walsh, A.; Urquhart, R.

    2016-08-01

    A spectral line image cube generated from 115 minutes of MWA data that covers a field of view of 400 sq, deg. around the Galactic Center is used to perform the first Search for ExtraTerrestrial Intelligence (SETI) with the Murchison Widefield Array (MWA). Our work constitutes the first modern SETI experiment at low radio frequencies, here between 103 and 133 MHz, paving the way for large-scale searches with the MWA and, in the future, the low-frequency Square Kilometre Array. Limits of a few hundred mJy beam-1 for narrowband emission (10 kHz) are derived from our data, across our 400 sq. deg. field of view. Within this field, 45 exoplanets in 38 planetary systems are known. We extract spectra at the locations of these systems from our image cube to place limits on the presence of narrow line emission from these systems. We then derive minimum isotropic transmitter powers for these exoplanets; a small handful of the closest objects (10 s of pc) yield our best limits of order 1014 W (Equivalent Isotropic Radiated Power). These limits lie above the highest power directional transmitters near these frequencies currently operational on Earth. A SETI experiment with the MWA covering the full accessible sky and its full frequency range would require approximately one month of observing time. The MWA frequency range, its southern hemisphere location on an extraordinarily radio quiet site, its very large field of view, and its high sensitivity make it a unique facility for SETI.

  4. Teacher Job Satisfaction: Lessons from the TSW Pathfinder Project

    ERIC Educational Resources Information Center

    Butt, Graham; Lance, Ann; Fielding, Antony; Gunter, Helen; Rayner, Steve; Thomas, Hywel

    2005-01-01

    Government policy assumes that modernization and remodelling will be effective as external intervention mechanisms to improve job satisfaction. Based on data collected as part of the evaluation of the "Transforming the School Workforce Pathfinder Project", an argument is presented here which suggests that internal management models may…

  5. The LISA Pathfinder Mission: Sub-picometer Interferometry in Space

    NASA Astrophysics Data System (ADS)

    Slutsky, Jacob; LISA Pathfinder Collaboration

    2018-01-01

    The European Space Agency’s LISA Pathfinder was a mission built to demonstrate the technologies essential to implement a space-based gravitational wave observatory sensitive in the milli-Hertz frequency band. ESA recently selected the LISA mission as such a future observatory, scheduled to launch in the early 2030s. LISA Pathfinder launched in late 2015 and concluded its final extended mission in July 2017, during which time it placed the two test masses into free fall and successfully measured the relative acceleration between them to a sensitivity that validates a number of critical technologies for LISA. These include drag-free control of the test masses, low noise microNewton thrusters to control the spacecraft, and sub-picometer-level laser metrology in space. The mission also served as a sensitive probe of the environmenal conditions in which LISA will operate. This poster summarizes the recent analysis results, with an eye towards the implications for the LISA mission.

  6. LISA Pathfinder: First steps to observing gravitational waves from space

    NASA Astrophysics Data System (ADS)

    McNamara, Paul; LISA Pathfinder Collaboration

    2017-01-01

    With the first direct detection of gravitational waves a little over a year ago, the gravitational window to the Universe has been opened. The gravitational wave spectrum spans many orders of magnitude in frequency, with several of the most interesting astronomical sources emitting gravitational waves at frequencies only observable from space The European Space Agency (ESA) has been active in the field of space-borne gravitational wave detection for many years, and in 2013 selected the Gravitational Universe as the science theme for the third large class mission in the Cosmic Vision science programme. In addition, ESA took the step of developing the LISA Pathfinder mission to demonstrate the critical technologies required for a future mission. The goal of the LISA Pathfinder mission is to place a test body in free fall such that any external forces (acceleration) are reduced to levels lower than those expected from the passage of a gravitational wave LISA Pathfinder was launched on the 3rd December 2015 from the European Spaceport in Kourou, French Guiana. After a series of 6 apogee raising manoeuvres, the satellite left earth orbit, and travelled to its final science orbit around the first Sun-Earth Lagrange point (L1). Following a relatively short commissioning phase, science operations began on 1st March 2016. In the following 3 months over 100 experiments and over 1500hours of noise measurements have been performed, demonstrating that the observation of gravitational waves from space can be realised.

  7. Laser Interferometry for Gravitational Wave Observation: LISA and LISA Pathfinder

    NASA Technical Reports Server (NTRS)

    Guzman, Felipe

    2010-01-01

    The Laser Interferometer Space Antenna (LISA) is a planned NASA-ESA gravitational wave observatory in the frequency range of 0.1mHz-100mHz. This observation band is inaccessible to ground-based detectors due to the large ground motions of the Earth. Gravitational wave sources for LISA include galactic binaries, mergers of supermasive black-hole binaries, extreme-mass-ratio inspirals, and possibly from as yet unimagined sources. LISA is a constellation of three spacecraft separated by 5 million km in an equilateral triangle, whose center follows the Earth in a heliocentric orbit with an orbital phase offset oF 20 degrees. Challenging technology is required to ensure pure geodetic trajectories of the six onboard test masses, whose distance fluctuations will be measured by interspacecraft laser interferometers with picometer accuracy. LISA Pathfinder is an ESA-launched technology demonstration mission of key LISA subsystems such us spacecraft control with micro-newton thrusters, test mass drag-free control, and precision laser interferometry between free-flying test masses. Ground testing of flight hardware of the Gravitational Reference Sensor and Optical Metrology subsystems of LISA Pathfinder is currently ongoing. An introduction to laser interferometric gravitational wave detection, ground-based observatories, and a detailed description of the two missions together with an overview of current investigations conducted by the community will bc discussed. The current status in development and implementation of LISA Pathfinder pre-flight systems and latest results of the ongoing ground testing efforts will also be presented

  8. Latin-square three-dimensional gage master

    DOEpatents

    Jones, L.

    1981-05-12

    A gage master for coordinate measuring machines has an nxn array of objects distributed in the Z coordinate utilizing the concept of a Latin square experimental design. Using analysis of variance techniques, the invention may be used to identify sources of error in machine geometry and quantify machine accuracy.

  9. Latin square three dimensional gage master

    DOEpatents

    Jones, Lynn L.

    1982-01-01

    A gage master for coordinate measuring machines has an nxn array of objects distributed in the Z coordinate utilizing the concept of a Latin square experimental design. Using analysis of variance techniques, the invention may be used to identify sources of error in machine geometry and quantify machine accuracy.

  10. Storage and computationally efficient permutations of factorized covariance and square-root information matrices

    NASA Technical Reports Server (NTRS)

    Muellerschoen, R. J.

    1988-01-01

    A unified method to permute vector-stored upper-triangular diagonal factorized covariance (UD) and vector stored upper-triangular square-root information filter (SRIF) arrays is presented. The method involves cyclical permutation of the rows and columns of the arrays and retriangularization with appropriate square-root-free fast Givens rotations or elementary slow Givens reflections. A minimal amount of computation is performed and only one scratch vector of size N is required, where N is the column dimension of the arrays. To make the method efficient for large SRIF arrays on a virtual memory machine, three additional scratch vectors each of size N are used to avoid expensive paging faults. The method discussed is compared with the methods and routines of Bierman's Estimation Subroutine Library (ESL).

  11. Shape calibration of a conformal ultrasound therapy array.

    PubMed

    McGough, R J; Cindric, D; Samulski, T V

    2001-03-01

    A conformal ultrasound phased array prototype with 96 elements was recently calibrated for electronic steering and focusing in a water tank. The procedure for calibrating the shape of this 2D therapy array consists of two steps. First, a least squares triangulation algorithm determines the element coordinates from a 21 x 21 grid of time delays. The triangulation algorithm also requires temperature measurements to compensate for variations in the speed of sound. Second, a Rayleigh-Sommerfeld formulation of the acoustic radiation integral is aligned to a second grid of measured pressure amplitudes in a least squares sense. This shape calibration procedure, which is applicable to a wide variety of ultrasound phased arrays, was tested on a square array panel consisting of 7- x 7-mm elements operating at 617 kHz. The simulated fields generated by an array of 96 equivalent elements are consistent with the measured data, even in the fine structure away from the primary focus and sidelobes. These two calibration steps are sufficient for the simulation model to predict successfully the pressure field generated by this conformal ultrasound phased array prototype.

  12. Overhead View of Pathfinder Landing Site

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Planimetric (overhead view) map of the landing site, to a distance of 20 meters from the spacecraft. North is at the top in this and Plates 3-5. To produce this map, images were geometrically projected onto an assumed mean surface representing the ground. Features above the ground plane (primarily rocks) therefore appear displaced radially outward; the amount of distortion increases systematically with distance. The upper surfaces of the lander and rover also appear enlarged and displaced because of their height. Primary grid (white) is based on the Landing Site Cartographic (LSC) coordinate system, defined with X eastward, Y north, and Z up, and origin located at the mean ground surface immediately beneath the deployed position of the IMP camera gimbal center. Secondary ticks (cyan) are based on the Mars local level (LL) frame, which has X north, Y east, Z down, with origin in the center of the lander baseplate. Rover positions (including APXS measurements) are commonly reported in the LL frame. Yellow grid shows polar coordinates based on the LSC system. Cartographic image processing by U.S. Geological Survey.

    NOTE: original caption as published in Science Magazine

    Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology (Caltech).

  13. Mars Pathfinder Project: Planetary Constants and Models

    NASA Technical Reports Server (NTRS)

    Vaughan, Robin

    1995-01-01

    This document provides a common set of astrodynamic constants and planetary models for use by the Mars Pathfinder Project. It attempts to collect in a single reference all the quantities and models in use across the project during development and for mission operations. These models are central to the navigation and mission design functions, but they are also used in other aspects of the project such as science observation planning and data reduction.

  14. Pathfinder technologies for bold new missions. [U.S. research and development program for space exploration

    NASA Technical Reports Server (NTRS)

    Sadin, Stanley R.; Rosen, Robert

    1987-01-01

    Project Pathfinder is a proposed U.S. Space Research and Technology program intended to enable bold new missions of space exploration. Pathfinder continues the advancement of technological capabilities and extends the foundation established under the Civil Space Technology Initiative, CSTI. By filling critical technological gaps, CSTI enhances access to Earth orbit and supports effective operations and science missions therein. Pathfinder, with a longer-term horizon, looks to a future that builds on Shuttle and Space Station and addresses technologies that support a range of exploration missions including: a return to the Moon to build an outpost; piloted missions to Mars; and continued scientific exploration of Earth and the other planets. The program's objective is to develop, within reasonable time frames, those emerging and innovative technologies that will make possible both new and enhanced missions and system concepts.

  15. Pathfinder Rover, Airbags, & Martian Terrain

    NASA Image and Video Library

    1997-07-05

    This is one of the first pictures taken by the camera on the Mars Pathfinder lander shortly after its touchdown at 10:07 AM Pacific Daylight Time on July 4, 1997. The small rover, named Sojourner, is seen in the foreground in its position on a solar panel of the lander. The white material on either side of the rover is part of the deflated airbag system used to absorb the shock of the landing. Between the rover and the horizon is the rock-strewn martian surface. Two hills are seen in the right distance, profiled against the light brown sky. http://photojournal.jpl.nasa.gov/catalog/PIA00611

  16. Pathfinders: Making a Way from Segregation to Community Life.

    ERIC Educational Resources Information Center

    O'Brien, Connie Lyle; Mount, Beth; O'Brien, John; Rosen, Fredda

    This paper describes the Pathfinders program in New York (New York), which works to facilitate the full integration of adults with developmental disabilities into workplaces and neighborhoods. The paper is organized around the question of whether students graduating from special education can find paid and volunteer work in community settings,…

  17. Asymptotic Analysis Of The Total Least Squares ESPRIT Algorithm'

    NASA Astrophysics Data System (ADS)

    Ottersten, B. E.; Viberg, M.; Kailath, T.

    1989-11-01

    This paper considers the problem of estimating the parameters of multiple narrowband signals arriving at an array of sensors. Modern approaches to this problem often involve costly procedures for calculating the estimates. The ESPRIT (Estimation of Signal Parameters via Rotational Invariance Techniques) algorithm was recently proposed as a means for obtaining accurate estimates without requiring a costly search of the parameter space. This method utilizes an array invariance to arrive at a computationally efficient multidimensional estimation procedure. Herein, the asymptotic distribution of the estimation error is derived for the Total Least Squares (TLS) version of ESPRIT. The Cramer-Rao Bound (CRB) for the ESPRIT problem formulation is also derived and found to coincide with the variance of the asymptotic distribution through numerical examples. The method is also compared to least squares ESPRIT and MUSIC as well as to the CRB for a calibrated array. Simulations indicate that the theoretic expressions can be used to accurately predict the performance of the algorithm.

  18. Arrays of flow channels with heat transfer embedded in conducting walls

    DOE PAGES

    Bejan, A.; Almerbati, A.; Lorente, S.; ...

    2016-04-20

    Here we illustrate the free search for the optimal geometry of flow channel cross-sections that meet two objectives simultaneously: reduced resistances to heat transfer and fluid flow. The element cross section and the wall material are fixed, while the shape of the fluid flow opening, or the wetted perimeter is free to vary. Two element cross sections are considered, square and equilateral triangular. We find that the two objectives are best met when the solid wall thickness is uniform, i.e., when the wetted perimeters are square and triangular, respectively. In addition, we consider arrays of square elements and triangular elements,more » on the basis of equal mass flow rate per unit of array cross sectional area. The conclusion is that the array of triangular elements meets the two objectives better than the array of square elements.« less

  19. Calibration and Stokes Imaging with Full Embedded Element Primary Beam Model for the Murchison Widefield Array

    NASA Astrophysics Data System (ADS)

    Sokolowski, M.; Colegate, T.; Sutinjo, A. T.; Ung, D.; Wayth, R.; Hurley-Walker, N.; Lenc, E.; Pindor, B.; Morgan, J.; Kaplan, D. L.; Bell, M. E.; Callingham, J. R.; Dwarakanath, K. S.; For, Bi-Qing; Gaensler, B. M.; Hancock, P. J.; Hindson, L.; Johnston-Hollitt, M.; Kapińska, A. D.; McKinley, B.; Offringa, A. R.; Procopio, P.; Staveley-Smith, L.; Wu, C.; Zheng, Q.

    2017-11-01

    The Murchison Widefield Array (MWA), located in Western Australia, is one of the low-frequency precursors of the international Square Kilometre Array (SKA) project. In addition to pursuing its own ambitious science programme, it is also a testbed for wide range of future SKA activities ranging from hardware, software to data analysis. The key science programmes for the MWA and SKA require very high dynamic ranges, which challenges calibration and imaging systems. Correct calibration of the instrument and accurate measurements of source flux densities and polarisations require precise characterisation of the telescope's primary beam. Recent results from the MWA GaLactic Extragalactic All-sky Murchison Widefield Array (GLEAM) survey show that the previously implemented Average Embedded Element (AEE) model still leaves residual polarisations errors of up to 10-20% in Stokes Q. We present a new simulation-based Full Embedded Element (FEE) model which is the most rigorous realisation yet of the MWA's primary beam model. It enables efficient calculation of the MWA beam response in arbitrary directions without necessity of spatial interpolation. In the new model, every dipole in the MWA tile (4 × 4 bow-tie dipoles) is simulated separately, taking into account all mutual coupling, ground screen, and soil effects, and therefore accounts for the different properties of the individual dipoles within a tile. We have applied the FEE beam model to GLEAM observations at 200-231 MHz and used false Stokes parameter leakage as a metric to compare the models. We have determined that the FEE model reduced the magnitude and declination-dependent behaviour of false polarisation in Stokes Q and V while retaining low levels of false polarisation in Stokes U.

  20. Mars Pathfinder and Mars Global Surveyor Outreach Compilation

    NASA Astrophysics Data System (ADS)

    1999-09-01

    This videotape is a compilation of the best NASA JPL (Jet Propulsion Laboratory) videos of the Mars Pathfinder and Mars Global Surveyor missions. The mission is described using animation and narration as well as some actual footage of the entire sequence of mission events. Included within these animations are the spacecraft orbit insertion; descent to the Mars surface; deployment of the airbags and instruments; and exploration by Sojourner, the Mars rover. JPL activities at spacecraft control during significant mission events are also included at the end. The spacecraft cameras pan the surrounding Mars terrain and film Sojourner traversing the surface and inspecting rocks. A single, brief, processed image of the Cydonia region (Mars face) at an oblique angle from the Mars Global Surveyor is presented. A description of the Mars Pathfinder mission, instruments, landing and deployment process, Mars approach, spacecraft orbit insertion, rover operation are all described using computer animation. Actual color footage of Sojourner as well as a 360 deg pan of the Mars terrain surrounding the spacecraft is provided. Lower quality black and white photography depicting Sojourner traversing the Mars surface and inspecting Martian rocks also is included.

  1. Mars Pathfinder and Mars Global Surveyor Outreach Compilation

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This videotape is a compilation of the best NASA JPL (Jet Propulsion Laboratory) videos of the Mars Pathfinder and Mars Global Surveyor missions. The mission is described using animation and narration as well as some actual footage of the entire sequence of mission events. Included within these animations are the spacecraft orbit insertion; descent to the Mars surface; deployment of the airbags and instruments; and exploration by Sojourner, the Mars rover. JPL activities at spacecraft control during significant mission events are also included at the end. The spacecraft cameras pan the surrounding Mars terrain and film Sojourner traversing the surface and inspecting rocks. A single, brief, processed image of the Cydonia region (Mars face) at an oblique angle from the Mars Global Surveyor is presented. A description of the Mars Pathfinder mission, instruments, landing and deployment process, Mars approach, spacecraft orbit insertion, rover operation are all described using computer animation. Actual color footage of Sojourner as well as a 360 deg pan of the Mars terrain surrounding the spacecraft is provided. Lower quality black and white photography depicting Sojourner traversing the Mars surface and inspecting Martian rocks also is included.

  2. Chimenea and other tools: Automated imaging of multi-epoch radio-synthesis data with CASA

    NASA Astrophysics Data System (ADS)

    Staley, T. D.; Anderson, G. E.

    2015-11-01

    In preparing the way for the Square Kilometre Array and its pathfinders, there is a pressing need to begin probing the transient sky in a fully robotic fashion using the current generation of radio telescopes. Effective exploitation of such surveys requires a largely automated data-reduction process. This paper introduces an end-to-end automated reduction pipeline, AMIsurvey, used for calibrating and imaging data from the Arcminute Microkelvin Imager Large Array. AMIsurvey makes use of several component libraries which have been packaged separately for open-source release. The most scientifically significant of these is chimenea, which implements a telescope-agnostic algorithm for automated imaging of pre-calibrated multi-epoch radio-synthesis data, of the sort typically acquired for transient surveys or follow-up. The algorithm aims to improve upon standard imaging pipelines by utilizing iterative RMS-estimation and automated source-detection to avoid so called 'Clean-bias', and makes use of CASA subroutines for the underlying image-synthesis operations. At a lower level, AMIsurvey relies upon two libraries, drive-ami and drive-casa, built to allow use of mature radio-astronomy software packages from within Python scripts. While targeted at automated imaging, the drive-casa interface can also be used to automate interaction with any of the CASA subroutines from a generic Python process. Additionally, these packages may be of wider technical interest beyond radio-astronomy, since they demonstrate use of the Python library pexpect to emulate terminal interaction with an external process. This approach allows for rapid development of a Python interface to any legacy or externally-maintained pipeline which accepts command-line input, without requiring alterations to the original code.

  3. Kilometric shock-associated events and microwave bursts

    NASA Technical Reports Server (NTRS)

    Kundu, M. R.; Macdowall, R. J.; Stone, R. G.

    1990-01-01

    The peak times of impulsive microwaves bursts are compared with those of shock-associated (SA) kilometric radio events. The first peaks in these two frequency regimes are usually well-correlated in time, but the last peaks of the SA events observed at 1 MHz occur an average of 20 min after the last impulsive microwave peaks. In some cases, the SA events overlap in time with the post-burst increases of microwave bursts; sometimes there is general correspondence in their intensity time profiles. These observations suggest that the earlier components of the SA events are usually caused by electrons accelerated in or near the microwave source region. The possibility that the later components of some SA events could be associated with nonthermal electrons responsible for microwave post-burst increases, although they have traditionally been attributed to electrons accelerated at type II burst producing shocks in the upper corona is discussed.

  4. NASA Ocean Altimeter Pathfinder Project. Report 1; Data Processing Handbook

    NASA Technical Reports Server (NTRS)

    Koblinsky, C. J.; Beckley, Brian D.; Ray, Richard D.; Wang, Yan-Ming; Tsaoussi, Lucia; Brenner, Anita; Williamson, Ron

    1998-01-01

    The NOAA/NASA Pathfinder program was created by the Earth Observing System (EOS) Program Office to determine how satellite-based data sets can be processed and used to study global change. The data sets are designed to be long time-sedes data processed with stable calibration and community consensus algorithms to better assist the research community. The Ocean Altimeter Pathfinder Project involves the reprocessing of all altimeter observations with a consistent set of improved algorithms, based on the results from TOPEX/POSEIDON (T/P), into easy-to-use data sets for the oceanographic community for climate research. This report describes the processing schemes used to produce a consistent data set and two of the products derived f rom these data. Other reports have been produced that: a) describe the validation of these data sets against tide gauge measurements and b) evaluate the statistical properties of the data that are relevant to climate change. The use of satellite altimetry for earth observations was proposed in the early 1960s. The first successful space based radar altimeter experiment was flown on SkyLab in 1974. The first successful satellite radar altimeter was flown aboard the Geos-3 spacecraft between 1975 and 1978. While a useful data set was collected from this mission for geophysical studies, the noise in the radar measured and incomplete global coverage precluded ft from inclusion in the Ocean Altimeter Pathfinder program. This program initiated its analysis with the Seasat mission, which was the first satellite radar altimeter flown for oceanography.

  5. Engineering a Large Scale Indium Nanodot Array for Refractive Index Sensing.

    PubMed

    Xu, Xiaoqing; Hu, Xiaolin; Chen, Xiaoshu; Kang, Yangsen; Zhang, Zhiping; B Parizi, Kokab; Wong, H-S Philip

    2016-11-23

    In this work, we developed a simple method to fabricate 12 × 4 mm 2 large scale nanostructure arrays and investigated the feasibility of indium nanodot (ND) array with different diameters and periods for refractive index sensing. Absorption resonances at multiple wavelengths from the visible to the near-infrared range were observed for various incident angles in a variety of media. Engineering the ND array with a centered square lattice, we successfully enhanced the sensitivity by 60% and improved the figure of merit (FOM) by 190%. The evolution of the resonance dips in the reflection spectra, of square lattice and centered square lattice, from air to water, matches well with the results of Lumerical FDTD simulation. The improvement of sensitivity is due to the enhancement of local electromagnetic field (E-field) near the NDs with centered square lattice, as revealed by E-field simulation at resonance wavelengths. The E-field is enhanced due to coupling between the two square ND arrays with [Formula: see text]x period at phase matching. This work illustrates an effective way to engineer and fabricate a refractive index sensor at a large scale. This is the first experimental demonstration of poor-metal (indium) nanostructure array for refractive index sensing. It also demonstrates a centered square lattice for higher sensitivity and as a better basic platform for more complex sensor designs.

  6. The NMR phased array.

    PubMed

    Roemer, P B; Edelstein, W A; Hayes, C E; Souza, S P; Mueller, O M

    1990-11-01

    We describe methods for simultaneously acquiring and subsequently combining data from a multitude of closely positioned NMR receiving coils. The approach is conceptually similar to phased array radar and ultrasound and hence we call our techniques the "NMR phased array." The NMR phased array offers the signal-to-noise ratio (SNR) and resolution of a small surface coil over fields-of-view (FOV) normally associated with body imaging with no increase in imaging time. The NMR phased array can be applied to both imaging and spectroscopy for all pulse sequences. The problematic interactions among nearby surface coils is eliminated (a) by overlapping adjacent coils to give zero mutual inductance, hence zero interaction, and (b) by attaching low input impedance preamplifiers to all coils, thus eliminating interference among next nearest and more distant neighbors. We derive an algorithm for combining the data from the phased array elements to yield an image with optimum SNR. Other techniques which are easier to implement at the cost of lower SNR are explored. Phased array imaging is demonstrated with high resolution (512 x 512, 48-cm FOV, and 32-cm FOV) spin-echo images of the thoracic and lumbar spine. Data were acquired from four-element linear spine arrays, the first made of 12-cm square coils and the second made of 8-cm square coils. When compared with images from a single 15 x 30-cm rectangular coil and identical imaging parameters, the phased array yields a 2X and 3X higher SNR at the depth of the spine (approximately 7 cm).

  7. Periodontal status among adolescents in Georgia. A pathfinder study.

    PubMed

    Levin, Liran; Margvelashvili, Vladimer; Bilder, Leon; Kalandadze, Manana; Tsintsadze, Nino; Machtei, Eli E

    2013-01-01

    Objectives. The aim of the present pathfinder study was to screen and map the periodontal status of Georgian population in accordance with the guidelines of the World Health Organization for population based surveys. Methods. During 2012, a pathfinder study was conducted to collect this data. For the periodontal portion of the study, 15-year-old school children were examined in the capital city of Tbilisi as well as in two other large cities and 4 smaller villages. All participants were examined by a trained dental team in a classroom using a dental mirror and a periodontal probe. Periodontal examination included plaque scores, calculus scores, probing depth measurements and bleeding on probing. These measurements were recorded for the Ramfjord index teeth. Results. A total of 397 15-year-old participants were examined in this pathfinder study. There were 240 females (60.45%) and 157 males (39.55%). Of the total participants 196 (49.37%) were urban adolescents while 201 (50.63%) were from rural communities. Mean probing depth was 3.34 ± 0.57 mm with a range of 1 to 10 mm; a relatively high proportion (34.26%) of these subjects presented with at least one site with pockets of 5 mm or deeper. Males presented with greater plaque, calculus and probing depths than females. When urban and rural populations were compared, urban participants presented with more plaque, probing depths and bleeding on probing. Greater pocket depths were found to be related to the presence of plaque calculus and bleeding on probing. Conclusions. Overall, rather high incidences of periodontal pockets ≥ 5 mm were detected in this population. This data should serve to prepare further more detailed epidemiological studies that will serve to plan and implement prevent and treat strategies for periodontal diseases in Georgia and also help make manpower decisions.

  8. PathFinder: reconstruction and dynamic visualization of metabolic pathways.

    PubMed

    Goesmann, Alexander; Haubrock, Martin; Meyer, Folker; Kalinowski, Jörn; Giegerich, Robert

    2002-01-01

    Beyond methods for a gene-wise annotation and analysis of sequenced genomes new automated methods for functional analysis on a higher level are needed. The identification of realized metabolic pathways provides valuable information on gene expression and regulation. Detection of incomplete pathways helps to improve a constantly evolving genome annotation or discover alternative biochemical pathways. To utilize automated genome analysis on the level of metabolic pathways new methods for the dynamic representation and visualization of pathways are needed. PathFinder is a tool for the dynamic visualization of metabolic pathways based on annotation data. Pathways are represented as directed acyclic graphs, graph layout algorithms accomplish the dynamic drawing and visualization of the metabolic maps. A more detailed analysis of the input data on the level of biochemical pathways helps to identify genes and detect improper parts of annotations. As an Relational Database Management System (RDBMS) based internet application PathFinder reads a list of EC-numbers or a given annotation in EMBL- or Genbank-format and dynamically generates pathway graphs.

  9. Mars PathFinder Rover Traverse Image

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This figure contains an azimuth-elevation projection of the 'Gallery Panorama.' The original Simple Cylindrical mosaic has been reprojected to the inside of a sphere so that lines of constant azimuth radiate from the center and lines of constant elevation are concentric circles. This projection preserves the resolution of the original panorama. Overlaid onto the projected Martian surface is a delineation of the Sojourner rover traverse path during the 83 Sols (Martian days) of Pathfinder surface operations. The rover path was reproduced using IMP camera 'end of day' and 'Rover movie' image sequences and rover vehicle telemetry data as references.

  10. Mars Pathfinder: The Wheel Abrasion Experiment

    NASA Technical Reports Server (NTRS)

    1996-01-01

    NASA Lewis Research Center's Wheel Abrasion Experiment (WAE) will measure the amount of wear on wheel surfaces of the Mars Pathfinder rover. WAE uses thin films of Al, Ni, and Pt (ranging in thickness from 200 to 1000 angstroms) deposited on black, anodized Al strips attached to the rover wheel. As the wheel moves across the martian surface, changes in film reflectivity will be monitored by reflected sunlight. These changes, measured as output from a special photodetector mounted on the rover chassis, will be due to abrasion of the metal films by martian surface sand, dust, and clay.

  11. Fiber-optic hydrophone array for acoustic surveillance in the littoral

    NASA Astrophysics Data System (ADS)

    Hill, David; Nash, Phillip

    2005-05-01

    We describe a fibre-optic hydrophone array system architecture that can be tailored to meet the underwater acoustic surveillance requirements of the military, counter terrorist and customs authorities in protecting ports and harbours, offshore production facilities or coastal approaches. Physically the fibre-optic hydrophone array is in the form of a lightweight cable, enabling rapid deployment from a small vessel. Based upon an optical architecture of time and wavelength multiplexed interferometric hydrophones, the array is comprised of a series of hydrophone sub-arrays. Using multiple sub-arrays, extended perimeters many tens of kilometres in length can be monitored. Interrogated via a long (~50km) optical fibre data link, the acoustic date is processed using the latest open architecture sonar processing platform, ensuring that acoustic targets below, on and above the surface are detected, tracked and classified. Results obtained from an at sea trial of a 96-channel hydrophone array are given, showing the passive detection and tracking of a diver, small surface craft and big ocean going ships beyond the horizon. Furthermore, we describe how the OptaMarine fibre-optic hydrophone array fits into an integrated multi-layered approach to port and harbour security consisting of active sonar for diver detection and hull imaging, as well as thermal imaging and CCTV for surface monitoring. Finally, we briefly describe a complimentary land perimeter intruder detection system consisting of an array of fibre optic accelerometers.

  12. Hillary Clinton visits Pathfinder projects in Brazil.

    PubMed

    1996-01-01

    In October 1995, US First Lady Hillary Clinton visited a maternity hospital in Salvador, Brazil, in which a family planning (FP)/reproductive health program has been administered by Pathfinder International since 1981 with funding from USAID. During her tour of the facility, Clinton learned about the high degree of unmet need for FP in the region which results from a lack of sufficient resources to meet demand. Clinton, in turn, praised the state of Bahia for its emphasis on FP in low-income areas.

  13. Mars pathfinder Rover egress deployable ramp assembly

    NASA Technical Reports Server (NTRS)

    Spence, Brian R.; Sword, Lee F.

    1996-01-01

    The Mars Pathfinder Program is a NASA Discovery Mission, led by the Jet Propulsion Laboratory, to launch and place a small planetary Rover for exploration on the Martian surface. To enable safe and successful egress of the Rover vehicle from the spacecraft, a pair of flight-qualified, deployable ramp assemblies have been developed. This paper focuses on the unique, lightweight deployable ramp assemblies. A brief mission overview and key design requirements are discussed. Design and development activities leading to qualification and flight systems are presented.

  14. A Wireless Electronic Nose System Using a Fe2O3 Gas Sensing Array and Least Squares Support Vector Regression

    PubMed Central

    Song, Kai; Wang, Qi; Liu, Qi; Zhang, Hongquan; Cheng, Yingguo

    2011-01-01

    This paper describes the design and implementation of a wireless electronic nose (WEN) system which can online detect the combustible gases methane and hydrogen (CH4/H2) and estimate their concentrations, either singly or in mixtures. The system is composed of two wireless sensor nodes—a slave node and a master node. The former comprises a Fe2O3 gas sensing array for the combustible gas detection, a digital signal processor (DSP) system for real-time sampling and processing the sensor array data and a wireless transceiver unit (WTU) by which the detection results can be transmitted to the master node connected with a computer. A type of Fe2O3 gas sensor insensitive to humidity is developed for resistance to environmental influences. A threshold-based least square support vector regression (LS-SVR)estimator is implemented on a DSP for classification and concentration measurements. Experimental results confirm that LS-SVR produces higher accuracy compared with artificial neural networks (ANNs) and a faster convergence rate than the standard support vector regression (SVR). The designed WEN system effectively achieves gas mixture analysis in a real-time process. PMID:22346587

  15. Experimental Evaluation of the High-Speed Motion Vector Measurement by Combining Synthetic Aperture Array Processing with Constrained Least Square Method

    NASA Astrophysics Data System (ADS)

    Yokoyama, Ryouta; Yagi, Shin-ichi; Tamura, Kiyoshi; Sato, Masakazu

    2009-07-01

    Ultrahigh speed dynamic elastography has promising potential capabilities in applying clinical diagnosis and therapy of living soft tissues. In order to realize the ultrahigh speed motion tracking at speeds of over thousand frames per second, synthetic aperture (SA) array signal processing technology must be introduced. Furthermore, the overall system performance should overcome the fine quantitative evaluation in accuracy and variance of echo phase changes distributed across a tissue medium. On spatial evaluation of local phase changes caused by pulsed excitation on a tissue phantom, investigation was made with the proposed SA signal system utilizing different virtual point sources that were generated by an array transducer to probe each component of local tissue displacement vectors. The final results derived from the cross-correlation method (CCM) brought about almost the same performance as obtained by the constrained least square method (LSM) extended to successive echo frames. These frames were reconstructed by SA processing after the real-time acquisition triggered by the pulsed irradiation from a point source. The continuous behavior of spatial motion vectors demonstrated the dynamic generation and traveling of the pulsed shear wave at a speed of one thousand frames per second.

  16. Hololujah; A One Kilometre Art Hologram

    NASA Astrophysics Data System (ADS)

    Warren, David

    2013-02-01

    This paper will outline the production of the white light transmission achromatic image art hologram titled Hololujah displaying forward projecting real imagery of text and measuring 100,000 × 3.5 cm. Materials and methods: The paper will cover the use of Slavich VRP-M film 33.3 × 1.05 metres that was exposed and processed as thirty-three and a third 100 × 105 cm frames. These thirty-three and a third frames were subsequently cut into one thousand 100 × 3.5 cm strips with their ends cold laminated together to form the kilometre length hologram. This paper will expand on the use of a Coherent Compass 315M, 532 nm, 150 mW DPSS laser diode in a lensless setup, using a single beam through diffuse glass, no isolation systems and a two minute exposure time with the film lying flat on the floor. Lastly, this paper will illustrate how the hologram was produced in a 220 × 200 × 300 cm confined area of a suburban bedroom. Theme: This artwork is a comment on the social networking site Twitter.

  17. Telescope Array Control System Based on Wireless Touch Screen Platform

    NASA Astrophysics Data System (ADS)

    Fu, X. N.; Huang, L.; Wei, J. Y.

    2016-07-01

    GWAC (Ground-based Wide Angle Cameras) are the ground-based observational instruments of the Sino-French cooperation SVOM (Space Variable Objects Monitor) astronomical satellite, and Mini-GWAC is a pathfinder and supplement of GWAC. In the context of the Mini-GWAC telescope array, this paper introduces the design and implementation of a kind of telescope array control system, which is based on wireless serial interface module to communicate. We describe the development and implementation of the system in detail in terms of control system principle, system hardware structure, software design, experiment, and test. The system uses the touch-control PC which is based on the Windows CE system as the upper-computer, the wireless transceiver module and PLC (Programmable Logic Controller) as the core. It has the advantages of low cost, reliable data transmission, and simple operation. So far, the control system has been applied to Mini-GWAC successfully.

  18. Java PathFinder User Guide

    NASA Technical Reports Server (NTRS)

    Havelund, Klaus

    1999-01-01

    The JAVA PATHFINDER, JPF, is a translator from a subset of JAVA 1.0 to PROMELA, the programming language of the SPIN model checker. The purpose of JPF is to establish a framework for verification and debugging of JAVA programming based on model checking. The main goal is to automate program verification such that a programmer can apply it in the daily work without the need for a specialist to manually reformulate a program into a different notation in order to analyze the program. The system is especially suited for analyzing multi-threaded JAVA applications, where normal testing usually falls short. The system can find deadlocks and violations of boolean assertions stated by the programmer in a special assertion language. This document explains how to Use JPF.

  19. The Stratospheric Aerosol and Gas Experiment (SAGE) IV Pathfinder

    NASA Astrophysics Data System (ADS)

    Hill, C. A.; Damadeo, R. P.; Gasbarre, J. F.

    2017-12-01

    Stratospheric ozone has been the subject of observation and research for decades. Measurements from satellites provided data on the initial decline in the late 1970s and early 1980s that supported the adoption of the Montreal Protocol to current observations hinting at potential recovery. Adequate determination of that recovery requires continuous and, in the case of multiple instruments, overlapping data records. However, most current satellite systems are well beyond their expected lifetimes and thus, with only a few "younger" instruments available, we look towards the future of satellite observations of stratospheric ozone to develop the Stratospheric Aerosol and Gas Experiment (SAGE) IV Pathfinder. The SAGE IV Pathfinder project will develop and validate a technology demonstration that will pave the way for a future SAGE IV mission. Utilizing solar occultation imaging, SAGE IV will be capable of measuring ozone, aerosol, and other trace gas species with the same quality as previous SAGE instruments but with greatly improved pointing knowledge. Furthermore, current technological advancements allow SAGE IV to fit within a CubeSat framework and make use of commercial hardware, significantly reducing the size and cost when compared with traditional missions and enabling sustainability of future measurements.

  20. Sedimentary Geochemistry of Martian Samples from the Pathfinder Mission

    NASA Technical Reports Server (NTRS)

    McLennan, Scott M.

    2001-01-01

    The purpose of this research project was to evaluate the APXS data collected on soils and rocks at the Pathfinder site in terms of sedimentary geochemistry. Below are described the major findings of this research: (1) An influential model to explain the chemical variation among Pathfinder soils and rocks is a two component mixing model where rocks of fairly uniform composition mix with soil of uniform composition; (2) The very strong positive correlation between MgO and SO, points to a control by a MgSO4 mineral however, spectroscopic data continue to suggest that Fe-sulfates, notably schwertmannite and jarosite, may be important components; (3) In an attempt to better understand the causes of complexities in mixing relationships, the possible influence of sedimentary transport has been evaluated; (4) Another aspect of this research has been to examine the possibility of sedimentary silica being a significant phase on Mars; and (5) On Earth, the geochemistry of sedimentary rocks has been used to constrain the chemical composition of the continental crust and an important part of this research was to evaluate this approach for Mars.

  1. Results from the Mars Pathfinder camera.

    PubMed

    Smith, P H; Bell, J F; Bridges, N T; Britt, D T; Gaddis, L; Greeley, R; Keller, H U; Herkenhoff, K E; Jaumann, R; Johnson, J R; Kirk, R L; Lemmon, M; Maki, J N; Malin, M C; Murchie, S L; Oberst, J; Parker, T J; Reid, R J; Sablotny, R; Soderblom, L A; Stoker, C; Sullivan, R; Thomas, N; Tomasko, M G; Wegryn, E

    1997-12-05

    Images of the martian surface returned by the Imager for Mars Pathfinder (IMP) show a complex surface of ridges and troughs covered by rocks that have been transported and modified by fluvial, aeolian, and impact processes. Analysis of the spectral signatures in the scene (at 440- to 1000-nanometer wavelength) reveal three types of rock and four classes of soil. Upward-looking IMP images of the predawn sky show thin, bluish clouds that probably represent water ice forming on local atmospheric haze (opacity approximately 0.5). Haze particles are about 1 micrometer in radius and the water vapor column abundance is about 10 precipitable micrometers.

  2. NASA Prepares Webb Telescope Pathfinder for Famous Chamber

    NASA Image and Video Library

    2015-04-13

    Engineers and technicians manually deployed the secondary mirror support structure (SMSS) of the James Webb Space Telescope's Pathfinder backplane test model, outside of a giant space simulation chamber called Chamber A, at NASA's Johnson Space Center in Houston. This historic test chamber was previously used in manned spaceflight missions and is being readied for a cryogenic test of a Webb telescope component. In the weightless environment of space, the SMSS is deployed by electric motors. On the ground, specially trained operators use a hand crank and a collection of mechanical ground support equipment to overcome the force of gravity. "This structure needs to be in the deployed configuration during the cryogenic test to see how the structure will operate in the frigid temperatures of space," said Will Rowland, senior mechanical test engineer for Northrop Grumman Aerospace Systems, Redondo Beach, California. "The test also demonstrates that the system works and can be successfully deployed." After the deployment was completed, Chamber A's circular door was opened and the rails (seen in the background of the photo) were installed so that the Pathfinder unit could be lifted, installed and rolled into the chamber on a cart. The team completed a fit check for the Pathfinder. Afterwards they readied the chamber for the cryogenic test, which will simulate the frigid temperatures the Webb telescope will encounter in space. “The team has been doing a great job keeping everything on schedule to getting our first optical test results, " said Lee Feinberg, NASA Optical Telescope Element Manager. The James Webb Space Telescope is the scientific successor to NASA's Hubble Space Telescope. It will be the most powerful space telescope ever built. Webb is an international project led by NASA with its partners, the European Space Agency and the Canadian Space Agency. Image credit: NASA/Desiree Stover Text credit: Laura Betz, NASA's Goddard Space Flight Center, Greenbelt

  3. Update on the SKA Offset Optics Design for the U.S. Technology Development Project

    NASA Technical Reports Server (NTRS)

    Imbriale, William A.; Cortes-Medellin, German; Baker, Lynn

    2011-01-01

    The U.S. design concept for the Square Kilometre Array (SKA) program is based on utilizing a large number of small-diameter dish antennas in the 12 to 15 meter diameter range. The Technology Development Project (TDP) is planning to design and build the first of these antennas to provide a demonstration of the technology and a solid base on which to estimate costs. The latest considerations for selecting both the optics and feed design are presented.

  4. The importance of atmospheric monitoring at the Pierre Auger Observatory

    NASA Astrophysics Data System (ADS)

    Dawson, Bruce R.

    The Pierre Auger Observatory is an ultra-high energy cosmic ray experiment employing a giant surface array of particle detectors together with telescopes to image fluorescence light from extensive air showers in the atmosphere. The atmosphere is the medium in which the incoming cosmic rays deposit their energy, and as a result we must monitor the characteristics of the atmosphere, including its density profile and light transmission properties, over the Observatory area of 3000 square kilometres.

  5. JPL Experience with the Mars Pathfinder, Mission Simulation Battery

    NASA Technical Reports Server (NTRS)

    Perrone, Dave; Ewell, Richard

    1997-01-01

    A summary of the Mars Pathfinder Battery is given. The battery survived 47 days at 25 deg. C; it survived a 7 month stand at 10 to -5 deg. C; it met and exceeded 40 ampere-hour capacity for EDL; it met the 30 cycle minimum for Mars surface operation; and the project power profile for MArs surface operation does not yield energy balance.

  6. The Role of APEX as a Pathfinder for AtLAST

    NASA Astrophysics Data System (ADS)

    Wyrowski, Friedrich

    2018-01-01

    Now more than 12 years in operation, the Atacama Pathfinder Experiment (APEX) 12 m submillimeter telescope has significantly contributed to a wide variety of submillimeter astronomy science areas, ranging from the discoveries of new molecules to large and deep imaging of the submillimeter sky. While ALMA operation is in full swing, APEX is strengthening its role not only as pathfinder for studying large source samples and spatial scales to prepare detailed high angular resolution ALMA follow ups, but also as fast response instruments to complement new results from ALMA. Furthermore, APEX ensures southern hemisphere access for submillimeter projects complementing archival Herschel research as well as new SOFIA science. With new broadband and multipixel receivers as well as large cameras for wide-field continuum imaging, APEX will pave the way towards the science envisioned with ATLAST. In this contribution, the current status and ongoing upgrades of APEX will be discussed, with an emphasis on the importance of continuous cutting edge science and state-of-the-art instrumentation that will bridge the gap towards ATLAST.

  7. NASA Ocean Altimeter Pathfinder Project. Report 2; Data Set Validation

    NASA Technical Reports Server (NTRS)

    Koblinsky, C. J.; Ray, Richard D.; Beckley, Brian D.; Bremmer, Anita; Tsaoussi, Lucia S.; Wang, Yan-Ming

    1999-01-01

    The NOAA/NASA Pathfinder program was created by the Earth Observing System (EOS) Program Office to determine how existing satellite-based data sets can be processed and used to study global change. The data sets are designed to be long time-series data processed with stable calibration and community consensus algorithms to better assist the research community. The Ocean Altimeter Pathfinder Project involves the reprocessing of all altimeter observations with a consistent set of improved algorithms, based on the results from TOPEX/POSEIDON (T/P), into easy-to-use data sets for the oceanographic community for climate research. Details are currently presented in two technical reports: Report# 1: Data Processing Handbook Report #2: Data Set Validation This report describes the validation of the data sets against a global network of high quality tide gauge measurements and provides an estimate of the error budget. The first report describes the processing schemes used to produce the geodetic consistent data set comprised of SEASAT, GEOSAT, ERS-1, TOPEX/ POSEIDON, and ERS-2 satellite observations.

  8. A data delivery system for IMOS, the Australian Integrated Marine Observing System

    NASA Astrophysics Data System (ADS)

    Proctor, R.; Roberts, K.; Ward, B. J.

    2010-09-01

    The Integrated Marine Observing System (IMOS, www.imos.org.au), an AUD 150 m 7-year project (2007-2013), is a distributed set of equipment and data-information services which, among many applications, collectively contribute to meeting the needs of marine climate research in Australia. The observing system provides data in the open oceans around Australia out to a few thousand kilometres as well as the coastal oceans through 11 facilities which effectively observe and measure the 4-dimensional ocean variability, and the physical and biological response of coastal and shelf seas around Australia. Through a national science rationale IMOS is organized as five regional nodes (Western Australia - WAIMOS, South Australian - SAIMOS, Tasmania - TASIMOS, New SouthWales - NSWIMOS and Queensland - QIMOS) surrounded by an oceanic node (Blue Water and Climate). Operationally IMOS is organized as 11 facilities (Argo Australia, Ships of Opportunity, Southern Ocean Automated Time Series Observations, Australian National Facility for Ocean Gliders, Autonomous Underwater Vehicle Facility, Australian National Mooring Network, Australian Coastal Ocean Radar Network, Australian Acoustic Tagging and Monitoring System, Facility for Automated Intelligent Monitoring of Marine Systems, eMarine Information Infrastructure and Satellite Remote Sensing) delivering data. IMOS data is freely available to the public. The data, a combination of near real-time and delayed mode, are made available to researchers through the electronic Marine Information Infrastructure (eMII). eMII utilises the Australian Academic Research Network (AARNET) to support a distributed database on OPeNDAP/THREDDS servers hosted by regional computing centres. IMOS instruments are described through the OGC Specification SensorML and where-ever possible data is in CF compliant netCDF format. Metadata, conforming to standard ISO 19115, is automatically harvested from the netCDF files

  9. Pathfinder, Volume 7. Number 4, Jul/Aug 2009. GEOINT in Action

    DTIC Science & Technology

    2009-08-01

    Rd,Bethesda,MD, 20816 -5003 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR’S...Communications 4600 Sangamore Road, Mail Stop D-39 Bethesda, MD 20816 -5003 Telephone: (301) 227-7388, DSN 287-7388 E-mail: pathfinder@nga.mil

  10. The cyclotron maser theory of AKR and Z-mode radiation. [Auroral Kilometric Radiation

    NASA Technical Reports Server (NTRS)

    Wu, C. S.

    1985-01-01

    The cyclotron maser mechanism which may be responsible for the generation of auroral kilometric radiation and Z-mode radiation is discussed. Emphasis is placed on the basic concepts of the cyclotron maser theory, particularly the relativistic effect of the cyclotron resonance condition. Recent development of the theory is reviewed. Finally, the results of a computer simulation study which helps to understand the nonlinear saturation of the maser instability are reported.

  11. A torsion pendulum test of the Lisa Pathfinder free-fall mode

    NASA Astrophysics Data System (ADS)

    Russano, Giuliana; Dolesi, Rita; Cavalleri, Antonella; Hueller, Mauro; Vitale, Stefano; Weber, William Joseph; Tu, HaiBo

    The LISA Pathfinder geodesic explorer mission for gravitational wave astronomy aims to demonstrate the proof of a low acceleration noise level. The relative acceleration between two test masses free falling in orbit is perturbed by the presence of a larger constant relative acceleration that must be actively compensated in order to keep the test particles centered inside an orbiting apparatus. The actuation force applied to compensate this effect introduces a dominant source of force noise. To suppress this noise source, a “free-fall” actuation control scheme has been designed: actuation is limited to brief impulses, with test masses in free fall in between two “kicks”, with this actuation-free motion then analyzed for the remaining sources of acceleration ultra noise. In this work, we will discuss and present preliminary data for an on-ground torsion pendulum experiment to test this technique, and the associated analysis algorithms, at a level nearing the sub-femto-g/sqrt(Hz) performance required for LISA Pathfinder.

  12. Exobiology site priorities for Mars Pathfinder

    NASA Technical Reports Server (NTRS)

    Farmer, Jack D.; Desmarais, David J.

    1994-01-01

    The fact that life developed on the Earth within the first billion years of its history makes it quite plausible that life may have also developed on Mars. If life did develop on Mars, it undoubtedly left behind a fossil record. Such a fossil record is likely to be more accessible than either subsurface environments that may harbor life, or scattered 'oases' that may be present at the surface. Consequently, the post-Viking approach of Mars exobiology has shifted focus to search for evidence of an ancient martian biosphere. This has led to the emergence of a new subdiscipline of paleontology, herein termed 'exopaleontology', which deals with the exploration for fossils on other planets and whose core concepts derive from Earth-based Precambrian paleontology, microbial ecology, and sedimentology. Potential targets on Mars for subaqueous spring deposits, sedimentary cements, and evaporites are ancient terminal lake basins where hydrological systems could have endured for some time under arid conditions. Potential targets for the Mars Pathfinder mission include channeled impact craters and areas of deranged drainage associated with outflows in northwest Arabia and Xanthe Terra, where water may have ponded temporarily to form lakes. The major uncertainty of such targets is their comparatively younger age and the potentially short duration of hydrological activity compared to older paleolake basins found in the southern hemisphere. However, it has been suggested that cycles of catastrophic flooding associated with Tharsis volcanism may have sustained a large body of water, Oceanus Borealis, in the northern plains area until quite late in martian history. Although problematic, the shoreline areas of the proposed northern ocean provide potential targets for a Mars Pathfinder mission aimed at exploring for carbonates or other potentially fossiliferous marine deposits. Carbonates and evaporites possess characteristic spectra signatures in the near-infrared and should be

  13. Global Climate Change Pathfinder: A Guide to Information Resources. Second Edition.

    ERIC Educational Resources Information Center

    Pintozzi, Chestalene; Jones, Douglas E.

    This pathfinder is a guide to scientific and technical aspects of global climate change including meteorological and climatological aspects; biological, agricultural, and public policy implications; and the chemical processes involved. Sources are arranged by type of publication and include: (1) 10 reference sources; (2) 12 bibliographies; (3) 44…

  14. Telescope Array Control System Based on Wireless Touch Screen Platform

    NASA Astrophysics Data System (ADS)

    Fu, Xia-nan; Huang, Lei; Wei, Jian-yan

    2017-10-01

    Ground-based Wide Angle Cameras (GMAC) are the ground-based observational facility for the SVOM (Space Variable Object Monitor) astronomical satellite of Sino-French cooperation, and Mini-GWAC is the pathfinder and supplement of GWAC. In the context of the Mini-GWAC telescope array, this paper introduces the design and implementation of a kind of telescope array control system based on the wireless touch screen platform. We describe the development and implementation of the system in detail in terms of control system principle, system hardware structure, software design, experiment, and test etc. The system uses a touch-control PC which is based on the Windows CE system as the upper computer, while the wireless transceiver module and PLC (Programmable Logic Controller) are taken as the system kernel. It has the advantages of low cost, reliable data transmission, and simple operation. And the control system has been applied to the Mini-GWAC successfully.

  15. Radio Sources in the NCP Region Observed with the 21 Centimeter Array

    NASA Astrophysics Data System (ADS)

    Zheng, Qian; Wu, Xiang-Ping; Johnston-Hollitt, Melanie; Gu, Jun-hua; Xu, Haiguang

    2016-12-01

    We present a catalog of 624 radio sources detected around the North Celestial Pole (NCP) with the 21 Centimeter Array (21CMA), a radio interferometer dedicated to the statistical measurement of the epoch of reionization (EoR). The data are taken from a 12 hr observation made on 2013 April 13, with a frequency coverage from 75 to 175 MHz and an angular resolution of ˜4‧. The catalog includes flux densities at eight sub-bands across the 21CMA bandwidth and provides the in-band spectral indices for the detected sources. To reduce the complexity of interferometric imaging from the so-called “w” term and ionospheric effects, the present analysis is restricted to the east-west baselines within 1500 m only. The 624 radio sources are found within 5° around the NCP down to ˜0.1 Jy. Our source counts are compared, and also exhibit a good agreement, with deep low-frequency observations made recently with the GMRT and MWA. In particular, for fainter radio sources below ˜1 Jy, we find a flattening trend of source counts toward lower frequencies. While the thermal noise (˜0.4 mJy) is well controlled to below the confusion limit, the dynamical range (˜104) and sensitivity of current 21CMA imaging are largely limited by calibration and deconvolution errors, especially the grating lobes of very bright sources, such as 3C061.1, in the NCP field, which result from the regular spacings of the 21CMA. We note that particular attention should be paid to the extended sources, and their modeling and removal may constitute a large technical challenge for current EoR experiments. Our analysis may serve as a useful guide to the design of next generation low-frequency interferometers like the Square Kilometre Array.

  16. Mars Pathfinder Wheel Abrasion Experiment Ground Test

    NASA Technical Reports Server (NTRS)

    Keith, Theo G., Jr.; Siebert, Mark W.

    1998-01-01

    The National Aeronautics and Space Administration (NASA) sent a mission to the martian surface, called Mars Pathfinder. The mission payload consisted of a lander and a rover. The primary purpose of the mission was demonstrating a novel entry, descent, and landing method that included a heat shield, a parachute, rockets, and a cocoon of giant air bags. Once on the surface, the spacecraft returned temperature measurements near the Martian surface, atmosphere pressure, wind speed measurements, and images from the lander and rover. The rover obtained 16 elemental measurements of rocks and soils, performed soil-mechanics, atmospheric sedimentation measurements, and soil abrasiveness measurements.

  17. Big Crater as Viewed by Pathfinder Lander

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The 'Big Crater' is actually a relatively small Martian crater to the southeast of the Mars Pathfinder landing site. It is 1500 meters (4900 feet) in diameter, or about the same size as Meteor Crater in Arizona. Superimposed on the rim of Big Crater (the central part of the rim as seen here) is a smaller crater nicknamed 'Rimshot Crater.' The distance to this smaller crater, and the nearest portion of the rim of Big Crater, is 2200 meters (7200 feet). To the right of Big Crater, south from the spacecraft, almost lost in the atmospheric dust 'haze,' is the large streamlined mountain nicknamed 'Far Knob.' This mountain is over 450 meters (1480 feet) tall, and is over 30 kilometers (19 miles) from the spacecraft. Another, smaller and closer knob, nicknamed 'Southeast Knob' can be seen as a triangular peak to the left of the flanks of the Big Crater rim. This knob is 21 kilometers (13 miles) southeast from the spacecraft.

    The larger features visible in this scene - Big Crater, Far Knob, and Southeast Knob - were discovered on the first panoramas taken by the IMP camera on the 4th of July, 1997, and subsequently identified in Viking Orbiter images taken over 20 years ago. The scene includes rocky ridges and swales or 'hummocks' of flood debris that range from a few tens of meters away from the lander to the distance of South Twin Peak. The largest rock in the nearfield, just left of center in the foreground, nicknamed 'Otter', is about 1.5 meters (4.9 feet) long and 10 meters (33 feet) from the spacecraft.

    This view of Big Crater was produced by combining 6 individual 'Superpan' scenes from the left and right eyes of the IMP camera. Each frame consists of 8 individual frames (left eye) and 7 frames (right eye) taken with different color filters that were enlarged by 500% and then co-added using Adobe Photoshop to produce, in effect, a super-resolution panchromatic frame that is sharper than an individual frame would be.

    Mars Pathfinder is the second in NASA

  18. DALiuGE: A graph execution framework for harnessing the astronomical data deluge

    NASA Astrophysics Data System (ADS)

    Wu, C.; Tobar, R.; Vinsen, K.; Wicenec, A.; Pallot, D.; Lao, B.; Wang, R.; An, T.; Boulton, M.; Cooper, I.; Dodson, R.; Dolensky, M.; Mei, Y.; Wang, F.

    2017-07-01

    The Data Activated Liu Graph Engine - DALiuGE- is an execution framework for processing large astronomical datasets at a scale required by the Square Kilometre Array Phase 1 (SKA1). It includes an interface for expressing complex data reduction pipelines consisting of both datasets and algorithmic components and an implementation run-time to execute such pipelines on distributed resources. By mapping the logical view of a pipeline to its physical realisation, DALiuGE separates the concerns of multiple stakeholders, allowing them to collectively optimise large-scale data processing solutions in a coherent manner. The execution in DALiuGE is data-activated, where each individual data item autonomously triggers the processing on itself. Such decentralisation also makes the execution framework very scalable and flexible, supporting pipeline sizes ranging from less than ten tasks running on a laptop to tens of millions of concurrent tasks on the second fastest supercomputer in the world. DALiuGE has been used in production for reducing interferometry datasets from the Karl E. Jansky Very Large Array and the Mingantu Ultrawide Spectral Radioheliograph; and is being developed as the execution framework prototype for the Science Data Processor (SDP) consortium of the Square Kilometre Array (SKA) telescope. This paper presents a technical overview of DALiuGE and discusses case studies from the CHILES and MUSER projects that use DALiuGE to execute production pipelines. In a companion paper, we provide in-depth analysis of DALiuGE's scalability to very large numbers of tasks on two supercomputing facilities.

  19. Pathfinder, v6 n6, Nov/Dec 2008. Foundation Data and Technology

    DTIC Science & Technology

    2008-12-01

    Geospatial-Intelligence Agency,Office of Corporate Communications,4600 Sangamore Road ,Bethesda,MD, 20816 -5003 8. PERFORMING ORGANIZATION REPORT...Communications 4600 Sangamore Road, Mail Stop D-54 Bethesda, MD 20816 -5003 Telephone: (301) 227-7388, DSN 287-7388 E-mail: pathfinder@nga.mil

  20. HOWARD EISEN, JPL'S LEAD MECHANICAL TECHNICIAN, HOLDS MARS PATHFINDER 'SOJOURNER' ROVER 1:1 SCALE DU

    NASA Technical Reports Server (NTRS)

    1996-01-01

    The Mars Pathfinder 'Sojourner' rover l:l scale duplicate test vehicle is held by Howard Eisen, its lead mechanical technician from the Jet Propulsion Laboratory, with Kennedy Space Center's Vehicle Assembly Building looming in the background. The launch of NASA's Mars Pathfinder spacecraft aboard a McDonnell Douglas Delta II rocket is scheduled for Monday, Dec. 2, at 2:09:11 a.m. EST. This is a single instantaneous target launch time without a second opportunity on that day. Liftoff will occur from Pad B at Launch Complex 17 on Cape Canaveral Air Station, Fla. There is a 24-day launch opportunity which extends through Dec. 31.

  1. Pathfinder. Volume 9, Number 3, May/June 2011

    DTIC Science & Technology

    2011-05-01

    Pathfinder magazine .” Any reproduction of graphics, photographs and imagery is subject to the original copyright. 2 On My Mind 5 NGA in the News ›› F E A...team analyst stationed in Baghdad to search for and identify advertising billboards in Baghdad, a large and mundane task. To a CA commander, however...unclassified Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 On My Mind Putting the Power of GEOINT in the Warfighter’s Hands As a

  2. Symbolic PathFinder: Symbolic Execution of Java Bytecode

    NASA Technical Reports Server (NTRS)

    Pasareanu, Corina S.; Rungta, Neha

    2010-01-01

    Symbolic Pathfinder (SPF) combines symbolic execution with model checking and constraint solving for automated test case generation and error detection in Java programs with unspecified inputs. In this tool, programs are executed on symbolic inputs representing multiple concrete inputs. Values of variables are represented as constraints generated from the analysis of Java bytecode. The constraints are solved using off-the shelf solvers to generate test inputs guaranteed to achieve complex coverage criteria. SPF has been used successfully at NASA, in academia, and in industry.

  3. Zebrafish foxP2 Zinc Finger Nuclease Mutant Has Normal Axon Pathfinding

    PubMed Central

    Xing, Lingyan; Hoshijima, Kazuyuki; Grunwald, David J.; Fujimoto, Esther; Quist, Tyler S.; Sneddon, Jacob; Chien, Chi-Bin; Stevenson, Tamara J.; Bonkowsky, Joshua L.

    2012-01-01

    foxP2, a forkhead-domain transcription factor, is critical for speech and language development in humans, but its role in the establishment of CNS connectivity is unclear. While in vitro studies have identified axon guidance molecules as targets of foxP2 regulation, and cell culture assays suggest a role for foxP2 in neurite outgrowth, in vivo studies have been lacking regarding a role for foxP2 in axon pathfinding. We used a modified zinc finger nuclease methodology to generate mutations in the zebrafish foxP2 gene. Using PCR-based high resolution melt curve analysis (HRMA) of G0 founder animals, we screened and identified three mutants carrying nonsense mutations in the 2nd coding exon: a 17 base-pair (bp) deletion, an 8bp deletion, and a 4bp insertion. Sequence analysis of cDNA confirmed that these were frameshift mutations with predicted early protein truncations. Homozygous mutant fish were viable and fertile, with unchanged body morphology, and no apparent differences in CNS apoptosis, proliferation, or patterning at embryonic stages. There was a reduction in expression of the known foxP2 target gene cntnap2 that was rescued by injection of wild-type foxP2 transcript. When we examined axon pathfinding using a pan-axonal marker or transgenic lines, including a foxP2-neuron-specific enhancer, we did not observe any axon guidance errors. Our findings suggest that foxP2 is not necessary for axon pathfinding during development. PMID:22937139

  4. Zebrafish foxP2 zinc finger nuclease mutant has normal axon pathfinding.

    PubMed

    Xing, Lingyan; Hoshijima, Kazuyuki; Grunwald, David J; Fujimoto, Esther; Quist, Tyler S; Sneddon, Jacob; Chien, Chi-Bin; Stevenson, Tamara J; Bonkowsky, Joshua L

    2012-01-01

    foxP2, a forkhead-domain transcription factor, is critical for speech and language development in humans, but its role in the establishment of CNS connectivity is unclear. While in vitro studies have identified axon guidance molecules as targets of foxP2 regulation, and cell culture assays suggest a role for foxP2 in neurite outgrowth, in vivo studies have been lacking regarding a role for foxP2 in axon pathfinding. We used a modified zinc finger nuclease methodology to generate mutations in the zebrafish foxP2 gene. Using PCR-based high resolution melt curve analysis (HRMA) of G0 founder animals, we screened and identified three mutants carrying nonsense mutations in the 2(nd) coding exon: a 17 base-pair (bp) deletion, an 8bp deletion, and a 4bp insertion. Sequence analysis of cDNA confirmed that these were frameshift mutations with predicted early protein truncations. Homozygous mutant fish were viable and fertile, with unchanged body morphology, and no apparent differences in CNS apoptosis, proliferation, or patterning at embryonic stages. There was a reduction in expression of the known foxP2 target gene cntnap2 that was rescued by injection of wild-type foxP2 transcript. When we examined axon pathfinding using a pan-axonal marker or transgenic lines, including a foxP2-neuron-specific enhancer, we did not observe any axon guidance errors. Our findings suggest that foxP2 is not necessary for axon pathfinding during development.

  5. Low-cost solar array structure development

    NASA Astrophysics Data System (ADS)

    Wilson, A. H.

    1981-06-01

    Early studies of flat-plate arrays have projected costs on the order of $50/square meter for installed array support structures. This report describes an optimized low-cost frame-truss structure that is estimated to cost below $25/square meter, including all markups, shipping an installation. The structure utilizes a planar frame made of members formed from light-gauge galvanized steel sheet and is supposed in the field by treated-wood trusses that are partially buried in trenches. The buried trusses use the overburden soil to carry uplift wind loads and thus to obviate reinforced-concrete foundations. Details of the concept, including design rationale, fabrication and assembly experience, structural testing and fabrication drawings are included.

  6. Low-cost solar array structure development

    NASA Technical Reports Server (NTRS)

    Wilson, A. H.

    1981-01-01

    Early studies of flat-plate arrays have projected costs on the order of $50/square meter for installed array support structures. This report describes an optimized low-cost frame-truss structure that is estimated to cost below $25/square meter, including all markups, shipping an installation. The structure utilizes a planar frame made of members formed from light-gauge galvanized steel sheet and is supposed in the field by treated-wood trusses that are partially buried in trenches. The buried trusses use the overburden soil to carry uplift wind loads and thus to obviate reinforced-concrete foundations. Details of the concept, including design rationale, fabrication and assembly experience, structural testing and fabrication drawings are included.

  7. Pathfinder, v6 n3, May/Jun 2008. Unifying the Intelligence Profession

    DTIC Science & Technology

    2008-06-01

    ADDRESS(ES) National Geospatial-Intelligence Agency,Office of Corporate Communications,4600 Sangamore Road ,Bethesda,MD, 20816 -5003 8. PERFORMING...Sangamore Road, Mail Stop D-54 Bethesda, MD 20816 -5003 Telephone: (301) 227-7388, DSN 287-7388 E-mail: pathfinder@nga.mil Director Vice Adm. Robert

  8. Performance measurements of hybrid PIN diode arrays

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

    Jernigan, J.G.; Arens, J.F.; Kramer, G.

    We report on the successful effort to develop hybrid PIN diode arrays and to demonstrate their potential as components of vertex detectors. Hybrid pixel arrays have been fabricated by the Hughes Aircraft Co. by bump bonding readout chips developed by Hughes to an array of PIN diodes manufactured by Micron Semiconductor Inc. These hybrid pixel arrays were constructed in two configurations. One array format having 10 {times} 64 pixels, each 120 {mu}m square, and the other format having 256 {times} 256 pixels, each 30 {mu}m square. In both cases, the thickness of the PIN diode layer is 300 {mu}m. Measurementsmore » of detector performance show that excellent position resolution can be achieved by interpolation. By determining the centroid of the charge cloud which spreads charge into a number of neighboring pixels, a spatial resolution of a few microns has been attained. The noise has been measured to be about 300 electrons (rms) at room temperature, as expected from KTC and dark current considerations, yielding a signal-to-noise ratio of about 100 for minimum ionizing particles. 4 refs., 13 figs.« less

  9. Predictive Array Design. A method for sampling combinatorial chemistry library space.

    PubMed

    Lipkin, M J; Rose, V S; Wood, J

    2002-01-01

    A method, Predictive Array Design, is presented for sampling combinatorial chemistry space and selecting a subarray for synthesis based on the experimental design method of Latin Squares. The method is appropriate for libraries with three sites of variation. Libraries with four sites of variation can be designed using the Graeco-Latin Square. Simulated annealing is used to optimise the physicochemical property profile of the sub-array. The sub-array can be used to make predictions of the activity of compounds in the all combinations array if we assume each monomer has a relatively constant contribution to activity and that the activity of a compound is composed of the sum of the activities of its constitutive monomers.

  10. Processing and Analysis of Mars Pathfinder Science Data at JPL's Science Data Processing Section

    NASA Technical Reports Server (NTRS)

    LaVoie, S.; Green, W.; Runkle, A.; Alexander, D.; Andres, P.; DeJong, E.; Duxbury, E.; Freda, D.; Gorjian, Z.; Hall, J.; hide

    1998-01-01

    The Mars Pathfinder mission required new capabilities and adaptation of existing capabilities in order to support science analysis and flight operations requirements imposed by the in-situ nature of the mission.

  11. The Fourier-Kelvin Stellar Interferometer (FKSI): A Discovery Class TPF/DARWIN Pathfinder Mission Concept

    NASA Technical Reports Server (NTRS)

    Danchi, W. C.; Allen, R. J.; Benford, D. J.; Deming, D.; Gezan, D. Y.; Kuchner, M.; Leisawitz, D. T.; Linfield, R.; Millan-Gabet, R.; Monnier, J. D.

    2003-01-01

    The Fourier-Kelvin Stellar Interferometer (FKSI) is a mission concept for an imaging and nulling interferometer for the mid-infrared spectral region (5-30 microns). FKSI is conceived as a scientific and technological pathfinder to TPF/DARWIN as well as SPIRIT, SPECS, and SAFIR. It will also be a high angular resolution system complementary to NGST. The scientific emphasis of the mission is on the evolution of protostellar systems, from just after the collapse of the precursor molecular cloud core, through the formation of the disk surrounding the protostar, the formation of planets in the disk, and eventual dispersal of the disk material. FKSI will also search for brown dwarfs and Jupiter mass and smaller planets, and could also play a very powerful role in the investigation of the structure of active galactic nuclei and extra-galactic star formation. We have been studying alternative interferometer architectures and beam combination techniques, and evaluating the relevant science and technology tradeoffs. Some of the technical challenges include the development of the cryocooler systems necessary for the telescopes and focal plane array, light and stiff but well-damped truss systems to support the telescopes, and lightweight and coolable optical telescopes. We present results of detailed design studies of the FKSI starting with a design consisting of five one meter diameter telescopes arranged along a truss structure in a linear non-redundant array, cooled to 35 K. A maximum baseline of 20 meters gives a nominal resolution of 26 mas at 5 microns. Using a Fizeau beam combination technique, a simple focal plane camera could be used to obtain both Fourier and spectral data simultaneously for a given orientation of the array. The spacecraft will be rotated to give sufficient Fourier data to reconstruct complex images of a broad range of astrophysical sources. Alternative and simpler three and two telescope designs emphasizing nulling and spectroscopy also have been

  12. Measuring Pilot Knowledge in Training: The Pathfinder Network Scaling Technique

    DTIC Science & Technology

    2007-01-01

    Network Scaling Technique Leah J. Rowe Roger W. Schvaneveldt L -3 Communications Arizona State University Mesa, AZ Mesa, AZ leah.rowe...7293 Page 2 of 8 Measuring Pilot Knowledge in Training: The Pathfinder Network Scaling Technique Leah J. Rowe Roger W. Schvaneveldt L -3...training. ABOUT THE AUTHORS Leah J. Rowe is a Training Research Specialist with L -3 Communications at the Air Force Research Laboratory

  13. Pathfinder autonomous rendezvous and docking project

    NASA Technical Reports Server (NTRS)

    Lamkin, Stephen (Editor); Mccandless, Wayne (Editor)

    1990-01-01

    Capabilities are being developed and demonstrated to support manned and unmanned vehicle operations in lunar and planetary orbits. In this initial phase, primary emphasis is placed on definition of the system requirements for candidate Pathfinder mission applications and correlation of these system-level requirements with specific requirements. The FY-89 activities detailed are best characterized as foundation building. The majority of the efforts were dedicated to assessing the current state of the art, identifying desired elaborations and expansions to this level of development and charting a course that will realize the desired objectives in the future. Efforts are detailed across all work packages in developing those requirements and tools needed to test, refine, and validate basic autonomous rendezvous and docking elements.

  14. Classification and Distribution of Mars Pathfinder Rocks Using Quantitative Morphologic Indices

    NASA Technical Reports Server (NTRS)

    Yingst, R. A.; Biederman, K. L.; Monhead, A. M.; Haldemann, A. F. C.; Kowalczyk, M. R.

    2004-01-01

    The Mars Pathfinder (MPF) landing site was predicted to contain a broad sampling of rock types varying in mineralogical, physical, mechanical and geochemical characteristics. Although rocks have been divided into several spectral categories based on Imager for Mars Pathfinder visible/near-infrared spectra, it has not been fully determined which of these stem from intrinsic mineralogical differences between rocks or rock surfaces, and which result from factors such as physical or chemical weathering. This has made isolation of unique mineralogy's difficult. Efforts in isolating and classifying spectral units among MPF rocks and soils have met with varying degrees of success, and the current understanding is such that many factors influencing spectral signatures cannot be quantified to a sufficient level so they may be removed. The result is that fundamental questions regarding information needed to reveal the present and past interactions between the rocks and rock surfaces and the Martian environment remain unanswered. But it is possible to approach the issue of identifying distinct rock and rock surface types from a different angle.

  15. Mars Array Technology Experiment Developed to Test Solar Arrays on Mars

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.

    2001-01-01

    Solar arrays will be the power supply for future missions to the planet Mars, including landers, rovers, and eventually human missions to explore the Martian surface. Until Mars Pathfinder landed in July 1997, no solar array had been used on the surface. The MATE package is intended to measure the solar energy reaching the surface, characterize the Martian environment to gather the baseline information required for designing power systems for long-duration missions, and to quantify the performance and degradation of advanced solar cells on the Martian surface. To measure the properties of sunlight reaching the Martian surface, MATE incorporates two radiometers and a visible/NIR spectrometer. The radiometers consist of multiple thermocouple junctions using thin-film technology. These devices generate a voltage proportional to the solar intensity. One radiometer measures the global broadband solar intensity, including both the direct and scattered sunlight, with a field of view of approximately 130. The second radiometer incorporates a slit to measure the direct (unscattered) intensity radiation. The direct radiometer can only be read once per day, with the Sun passing over the slit. The spectrometer measures the global solar spectrum with two 256-element photodiode arrays, one Si sensitive in the visible range (300 to 1100 nm), and a second InGaAs sensitive to the near infrared (900 to 1700 nm). This range covers 86 percent of the total energy from the Sun, with approximately 5-nm resolution. Each photodiode array has its own fiber-optic feed and grating. Although the purpose of the MATE is to gather data useful in designing solar arrays for Mars surface power systems, the radiometer and spectrometer measurements are expected to also provide important scientific data for characterizing the properties of suspended atmospheric dust. In addition to measuring the solar environment of Mars, MATE will measure the performance of five different individual solar cell types

  16. High School Students' Knowledge of a Square as a Basis for Developing a Geometric Learning Progression

    ERIC Educational Resources Information Center

    Seah, Rebecca; Horne, Marj; Berenger, Adrian

    2016-01-01

    This study surveyed and analysed four secondary school students' writing about a square. Sfard's discursive approach to understanding mathematical discourse was used to analyse the responses collected from 214 Australian secondary school students. The results showed that geometric knowledge was developed experientially and not developmentally.…

  17. Generation of auroral kilometric and Z mode radiation by the cyclotron maser mechanism

    NASA Technical Reports Server (NTRS)

    Omidi, N.; Gurnett, D. A.; Wu, C. S.

    1984-01-01

    The relativistic Doppler-shifted cyclotron resonance condition for EM wave interactions with a plasma defines an ellipse in velocity space when the product of the index of refraction and cosine of the wave normal angle is less than or equal to unity, and defines a partial ellipse when the product is greater than unity. It is also noted that waves with frequencies greater than the gyrofrequency can only resonate with particles moving in the same direction along the magnetic field, while waves with lower frequencies than these resonate with particles moving in both directions along the magnetic field. It is found, in the case of auroral kilometric radiation, that both the upgoing and the downgoing electrons are unstable and can give rise to this radiation's growth. The magnitudes of the growth rates for both the upgoing and downgoing auroral kilometric radiation are comparable, and indicate that the path lengths needed to account for the observed intensities of this radiation are of the order of a few hundred km, which is probably too large. Growth rate calculations for the Z mode radiation show that, for wave frequencies just below the gyrofrequency and wave normal angles at or near 90 deg, the electron distribution is unstable and the growth rates are large enough to account for the observed intensities.

  18. Interchange rotation factors and player characteristics influence physical and technical performance in professional Australian Rules football.

    PubMed

    Dillon, Patrick A; Kempton, Thomas; Ryan, Samuel; Hocking, Joel; Coutts, Aaron J

    2018-03-01

    To examine the effects of match-related and individual player characteristics on activity profile and technical performance during rotations in professional Australian football. Longitudinal observational study. Global positioning system data and player rating scores were collected from 33 professional Australian football players during 15 Australian football League matches. Player rating scores were time aligned with their relative total and high-speed running (HSR) distance (>20kmh -1 ) for each on ground rotation. Individual players' maximal aerobic running speed (MAS) was determined from a two-kilometre trial. A multilevel linear mixed model was used to examine the influence of rotations on physical activity profiles and skill execution during match play. Rotation duration and accumulated distance resulted in a trivial-to-moderate reduction in relative total and HSR distances as well as relative rating points. The number of disposals in a rotation had a small positive effect on relative total and HSR distances and a large positive effect on relative rating points. MAS was associated with a moderate-to-large increase in relative total distance, but had a large negative effect on relative rating points. Previous rotation time, stoppages and the number of rotations in the quarter had a trivial-to-small negative effect on relative total and HSR distances. A greater speed (mmin -1 ) was associated with a trivial increase in rating points during a rotation, while there was a trivial decrease in relative total distance as rating points increased. The complex relationship between factors that influence activity profile and technical performance during rotations in Australian football needs to be considered when interpreting match performance. Copyright © 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  19. LISA pathfinder optical interferometry

    NASA Astrophysics Data System (ADS)

    Braxmaier, Claus; Heinzel, Gerhard; Middleton, Kevin F.; Caldwell, Martin E.; Konrad, W.; Stockburger, H.; Lucarelli, S.; te Plate, Maurice B.; Wand, V.; Garcia, A. C.; Draaisma, F.; Pijnenburg, J.; Robertson, D. I.; Killow, Christian; Ward, Harry; Danzmann, Karsten; Johann, Ulrich A.

    2004-09-01

    The LISA Technology Package (LTP) aboard of LISA pathfinder mission is dedicated to demonstrate and verify key technologies for LISA, in particular drag free control, ultra-precise laser interferometry and gravitational sensor. Two inertial sensor, the optical interferometry in between combined with the dimensional stable Glass ceramic Zerodur structure are setting up the LTP. The validation of drag free operation of the spacecraft is planned by measuring laser interferometrically the relative displacement and tilt between two test masses (and the optical bench) with a noise levels of 10pm/√Hz and 10 nrad/√Hz between 3mHz and 30mHz. This performance and additionally overall environmental tests was currently verified on EM level. The OB structure is able to support two inertial sensors (≍17kg each) and to withstand 25 g design loads as well as 0...40°C temperature range. Optical functionality was verified successfully after environmental tests. The engineering model development and manufacturing of the optical bench and interferometry hardware and their verification tests will be presented.

  20. Australian Space Situational Awareness Capability Demonstrations

    NASA Astrophysics Data System (ADS)

    Morreale, B.; Bessell, T.; Rutten, M.; Cheung, B.

    Australia is increasing its contribution to the global space situational awareness (SSA) problem by committing to acquire and operate SSA sensors. Over the last year, a series of collaborative SSA experiments have been undertaken to demonstrate the capabilities of Australian sensors. These experiments aimed to demonstrate how existing Australian sensors could perform in a surveillance of space role, prove passive radar’s capability to observe low earth orbit (LEO) satellites and perform SSA handoffs to optical sensors. The trials established a data sharing and communications protocol that bridged defence, academia, and industry partners. Geographically dispersed optical assets, including the Falcon telescope in Canberra, Raven telescopes in Exmouth (Western Australia) and Defence Science and Technology (DST) Telescopes in Adelaide (South Australia) collected on LEO satellites and established cueing protocols. The Murchison Widefield Array (MWA) located in Western Australia, demonstrated the capability of passive radar as an SSA asset after successfully observing LEO satellites based on reflected terrestrial radio signals. The combination of radar and optical SSA assets allows for the exploitation of each sensors unique advantages and locations across the Australian continent. This paper outlines the capabilities and diversity of Australian optical and radar sensors as demonstrated by field trials in 2016 and 2017. It suggests future potential for harnessing novel radar and optical integration techniques to supplement high-value assets such as the Space Surveillance Telescope as part of the Space Surveillance Network.

  1. Recent results from the Telescope Array Experiment

    NASA Astrophysics Data System (ADS)

    Abbasi, Rasha; Telescope Array Collaboration

    2016-03-01

    The Telescope Array (TA) is the largest ultrahigh energy cosmic rays detector in the northern hemisphere. TA is a hybrid detector comprised of three air fluorescence stations and a large surface array consisting of 507 scintillator counters. Each of the three fluorescence stations, located at the periphery of the ground array, views 108 degrees in azimuth and up to 30 degrees in elevation. The surface detectors are arranged in a square grid of 1.2 km spacing, covering over 700 square kilometers. TA has collected more than seven years of data. In this talk, we will present some of the main results on the cosmic rays composition and energy spectrum obtained by TA and its low energy extension (TALE). Finally, we will present our results from the search for arrival direction anisotropy, including the observed large excess of events at the highest energies, seen in the region of the northern sky centered on Ursa Major. Based on the current results, the ``hot spot'' in particular, TA is pursuing the expansion of the surface array to four times its current size.

  2. Superconducting Bolometer Array Architectures

    NASA Technical Reports Server (NTRS)

    Benford, Dominic; Chervenak, Jay; Irwin, Kent; Moseley, S. Harvey; Shafer, Rick; Staguhn, Johannes; Wollack, Ed; Oegerle, William (Technical Monitor)

    2002-01-01

    The next generation of far-infrared and submillimeter instruments require large arrays of detectors containing thousands of elements. These arrays will necessarily be multiplexed, and superconducting bolometer arrays are the most promising present prospect for these detectors. We discuss our current research into superconducting bolometer array technologies, which has recently resulted in the first multiplexed detections of submillimeter light and the first multiplexed astronomical observations. Prototype arrays containing 512 pixels are in production using the Pop-Up Detector (PUD) architecture, which can be extended easily to 1000 pixel arrays. Planar arrays of close-packed bolometers are being developed for the GBT (Green Bank Telescope) and for future space missions. For certain applications, such as a slewed far-infrared sky survey, feedhorncoupling of a large sparsely-filled array of bolometers is desirable, and is being developed using photolithographic feedhorn arrays. Individual detectors have achieved a Noise Equivalent Power (NEP) of -10(exp 17) W/square root of Hz at 300mK, but several orders of magnitude improvement are required and can be reached with existing technology. The testing of such ultralow-background detectors will prove difficult, as this requires optical loading of below IfW. Antenna-coupled bolometer designs have advantages for large format array designs at low powers due to their mode selectivity.

  3. Extensive degeneracy, Coulomb phase and magnetic monopoles in artificial square ice.

    PubMed

    Perrin, Yann; Canals, Benjamin; Rougemaille, Nicolas

    2016-12-15

    Artificial spin-ice systems are lithographically patterned arrangements of interacting magnetic nanostructures that were introduced as way of investigating the effects of geometric frustration in a controlled manner. This approach has enabled unconventional states of matter to be visualized directly in real space, and has triggered research at the frontier between nanomagnetism, statistical thermodynamics and condensed matter physics. Despite efforts to create an artificial realization of the square-ice model-a two-dimensional geometrically frustrated spin-ice system defined on a square lattice-no simple geometry based on arrays of nanomagnets has successfully captured the macroscopically degenerate ground-state manifold of the model. Instead, square lattices of nanomagnets are characterized by a magnetically ordered ground state that consists of local loop configurations with alternating chirality. Here we show that all of the characteristics of the square-ice model are observed in an artificial square-ice system that consists of two sublattices of nanomagnets that are vertically separated by a small distance. The spin configurations we image after demagnetizing our arrays reveal unambiguous signatures of a Coulomb phase and algebraic spin-spin correlations, which are characterized by the presence of 'pinch' points in the associated magnetic structure factor. Local excitations-the classical analogues of magnetic monopoles-are free to evolve in an extensively degenerate, divergence-free vacuum. We thus provide a protocol that could be used to investigate collective magnetic phenomena, including Coulomb phases and the physics of ice-like materials.

  4. Control over self-assembly of diblock copolymers on hexagonal and square templates for high area density circuit boards.

    PubMed

    Feng, Jie; Cavicchi, Kevin A; Heinz, Hendrik

    2011-12-27

    Self-assembled diblock copolymer melts on patterned substrates can induce a smaller characteristic domain spacing compared to predefined lithographic patterns and enable the manufacture of circuit boards with a high area density of computing and storage units. Monte Carlo simulation using coarse-grain models of polystyrene-b-polydimethylsiloxane shows that the generation of high-density hexagonal and square patterns is controlled by the ratio N(D) of the surface area per post and the surface area per spherical domain of neat block copolymer. N(D) represents the preferred number of block copolymer domains per post. Selected integer numbers support the formation of ordered structures on hexagonal (1, 3, 4, 7, 9) and square (1, 2, 5, 7) templates. On square templates, only smaller numbers of block copolymer domains per post support the formation of ordered arrays with significant stabilization energies relative to hexagonal morphology. Deviation from suitable integer numbers N(D) increases the likelihood of transitional morphologies between square and hexagonal. Upon increasing the spacing of posts on the substrate, square arrays, nested square arrays, and disordered hexagonal morphologies with multiple coordination numbers were identified, accompanied by a decrease in stabilization energy. Control over the main design parameter N(D) may allow an up to 7-fold increase in density of spherical block copolymer domains per surface area in comparison to the density of square posts and provide access to a wide range of high-density nanostructures to pattern electronic devices.

  5. Advanced European Network of E-Infrastructures for Astronomy with the SKA

    NASA Astrophysics Data System (ADS)

    Massardi, Marcella

    2017-11-01

    Here, I present the AENEAS (Advanced European Network of E-infrastructures for Astronomy with the SKA) project has been funded in the Horizon 2020 Work Programme call "Research and Innovation Actions for International Co-operation on high-end e-infrastructure requirements" supporting the Square Kilometre Array (SKA). INAF is contributing to all the AENEAS working packages and leading the WP5 - Access and Knowledge Creation (WP leader M. Massardi IRA-ARC), participants from IRA (Brand, Nanni, Venturi) ,OACT(Becciani, Costa, Umana), OATS (Smareglia, Knapic, Taffoni)

  6. Grid resolution and solution convergence for Mars Pathfinder forebody

    NASA Technical Reports Server (NTRS)

    Nettelhorst, Heather L.; Mitcheltree, Robert A.

    1994-01-01

    As part of the Discovery Program, NASA Plans to launch a series of probes to Mars. The Mars Pathfinder project is the first of this series with a scheduled Mars arrival in July 1997. The entry vehicle will perform a direct entry into the atmosphere and deliver a lander to the surface. Predicting the entry vehicle's flight performance and designing the forebody heatshield requires knowledge of the expected aerothermodynamic environment. Much of this knowledge can be obtained through computational fluid dynamic (CFD) analysis.

  7. Java PathFinder: A Translator From Java to Promela

    NASA Technical Reports Server (NTRS)

    Havelund, Klaus

    1999-01-01

    JAVA PATHFINDER, JPF, is a prototype translator from JAVA to PROMELA, the modeling language of the SPIN model checker. JPF is a product of a major effort by the Automated Software Engineering group at NASA Ames to make model checking technology part of the software process. Experience has shown that severe bugs can be found in final code using this technique, and that automated translation from a programming language to a modeling language like PROMELA can help reducing the effort required.

  8. Fast drift kilometric radio bursts and solar proton events

    NASA Technical Reports Server (NTRS)

    Cliver, E. W.; Kahler, S. W.; Cane, H. V.; Mcguire, R. E.; Vonrosenvinge, T. T.; Stone, R. G.

    1985-01-01

    Initial results of a comparative study of major fast drift kilometric bursts and solar proton events from Sep. 1978 to Feb. 1983 are presented. It was found that only about half of all intense, long duration ( 40 min above 500 sfu) 1 MHz bursts can be associated with F 20 MeV proton events. However, for the subset of such fast drift bursts accompanied by metric Type 2 and/or 4 activity (approximately 40% of the total), the degree of association with 20 MeV events is 80%. For the reverse association, it was found that proton events with J( 20 MeV) 0.01 1 pr cm(-2)s(-1)sr(-1)MeV(-1) were typically (approximately 80% of the time) preceded by intense 1 MHz bursts that exceeded the 500 sfu level for times 20 min (median duration approximately 35 min).

  9. Lunar ionosphere exploration method using auroral kilometric radiation

    NASA Astrophysics Data System (ADS)

    Goto, Yoshitaka; Fujimoto, Takamasa; Kasahara, Yoshiya; Kumamoto, Atsushi; Ono, Takayuki

    2011-01-01

    The evidence of a lunar ionosphere provided by radio occultation experiments performed by the Soviet spacecraft Luna 19 and 22 has been controversial for the past three decades because the observed large density is difficult to explain theoretically without magnetic shielding from the solar wind. The KAGUYA mission provided an opportunity to investigate the lunar ionosphere with another method. The natural plasma wave receiver (NPW) and waveform capture (WFC) instruments, which are subsystems of the lunar radar sounder (LRS) on board the lunar orbiter KAGUYA, frequently observe auroral kilometric radiation (AKR) propagating from the Earth. The dynamic spectra of the AKR sometimes exhibit a clear interference pattern that is caused by phase differences between direct waves and waves reflected on a lunar surface or a lunar ionosphere if it exists. It was hypothesized that the electron density profiles above the lunar surface could be evaluated by comparing the observed interference pattern with the theoretical interference patterns constructed from the profiles with ray tracing. This method provides a new approach to examining the lunar ionosphere that does not involve the conventional radio occultation technique.

  10. Prospects for Future Synergies Between SKA and AtLAST

    NASA Astrophysics Data System (ADS)

    Wagg, Jeff

    2018-01-01

    The Square Kilometre Array will be the next major global radio astronomy observatory. Being built in two phases, the first phase will consist of a low frequency array in Australia and a mid to high frequency array of dishes in the Karoo of South Africa. The design of SKA1 is nearly complete with the expectation that construction should begin within the next two years. A significant fraction of the observing time on both SKA1-MID and SKA1-LOW will likely be devoted to large survey programmes covering a broad range of science objectives. Given the timeline for these SKA1 programmes to be completed, it is anticipated that they could naturally complement future high frequency surveys using AtLAST. I will highlight a few areas where such synergies should exist.

  11. Pathfinder, v6 n5, Sep/Oct 2008. Shielding Our Home and Nation

    DTIC Science & Technology

    2008-10-01

    Agency,Office of Corporate Communications,4600 Sangamore Road ,Bethesda,MD, 20816 -5003 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING... 20816 -5003 Telephone: (301) 227-7388, DSN 287-7388 E-mail: pathfinder@nga.mil Director Vice Adm. Robert B. Murrett, U.S. Navy Deputy Director

  12. Influence of the solar wind/interplanetary medium on Saturnian kilometric radiation

    NASA Technical Reports Server (NTRS)

    Rucker, Helmut O.; Desch, M. D.

    1990-01-01

    Previous studies on the periodicities of the Saturnian kilometric radiation (SKR) suggested a considerable solar wind influence on the occurrence of SKR, so it was obvious to investigate the relationship between parameters of the solar wind/interplanetary medium and this Saturnian radio component. Voyager 2 data from the Plasma Science experiment, the Magnetometer experiment and the Planetary Radio Astronomy experiment were used to analyze the external control of SKR. Out of the examined quantities known to be important in controlling magnetospheric processes this investigation yielded a dominance of the solar wind momentum, ram pressure and kinetic energy flux, in stimulating SKR and controlling its activity and emitted energy, and confirmed the results of the Voyager 1 analysis.

  13. Mars pathfinder lander deployment mechanisms

    NASA Technical Reports Server (NTRS)

    Gillis-Smith, Greg R.

    1996-01-01

    The Mars Pathfinder Lander employs numerous mechanisms, as well as autonomous mechanical functions, during its Entry, Descent and Landing (EDL) Sequence. This is the first US lander of its kind, since it is unguided and airbag-protected for hard landing using airbags, instead of retro rockets, to soft land. The arrival condition, location, and orientation of the Lander will only be known by the computer on the Lander. The Lander will then autonomously perform the appropriate sequence to retract the airbags, right itself, and open, such that the Lander is nearly level with no airbag material covering the solar cells. This function uses two different types of mechanisms - the Airbag Retraction Actuators and the Lander Petal Actuators - which are designed for the high torque, low temperature, dirty environment and for limited life application. The development of these actuators involved investigating low temperature lubrication, Electrical Discharge Machining (EDM) to cut gears, and gear design for limited life use.

  14. LISA Pathfinder Instrument Data Analysis

    NASA Technical Reports Server (NTRS)

    Guzman, Felipe

    2010-01-01

    LISA Pathfinder (LPF) is an ESA-launched demonstration mission of key technologies required for the joint NASA-ESA gravitational wave observatory in space, LISA. As part of the LPF interferometry investigations, analytic models of noise sources and corresponding noise subtraction techniques have been developed to correct for effects like the coupling of test mass jitter into displacement readout, and fluctuations of the laser frequency or optical pathlength difference. Ground testing of pre-flight hardware of the Optical Metrology subsystem is currently ongoing at the Albert Einstein Institute Hannover. In collaboration with NASA Goddard Space Flight Center, the LPF mission data analysis tool LTPDA is being used to analyze the data product of these tests. Furthermore, the noise subtraction techniques and in-flight experiment runs for noise characterization are being defined as part of the mission experiment master plan. We will present the data analysis outcome of preflight hardware ground tests and possible noise subtraction strategies for in-flight instrument operations.

  15. Imager for Mars Pathfinder (IMP) image calibration

    USGS Publications Warehouse

    Reid, R.J.; Smith, P.H.; Lemmon, M.; Tanner, R.; Burkland, M.; Wegryn, E.; Weinberg, J.; Marcialis, R.; Britt, D.T.; Thomas, N.; Kramm, R.; Dummel, A.; Crowe, D.; Bos, B.J.; Bell, J.F.; Rueffer, P.; Gliem, F.; Johnson, J. R.; Maki, J.N.; Herkenhoff, K. E.; Singer, Robert B.

    1999-01-01

    The Imager for Mars Pathfinder returned over 16,000 high-quality images from the surface of Mars. The camera was well-calibrated in the laboratory, with <5% radiometric uncertainty. The photometric properties of two radiometric targets were also measured with 3% uncertainty. Several data sets acquired during the cruise and on Mars confirm that the system operated nominally throughout the course of the mission. Image calibration algorithms were developed for landed operations to correct instrumental sources of noise and to calibrate images relative to observations of the radiometric targets. The uncertainties associated with these algorithms as well as current improvements to image calibration are discussed. Copyright 1999 by the American Geophysical Union.

  16. Interactions of UNC-34 Enabled With Rac GTPases and the NIK Kinase MIG-15 in Caenorhabditis elegans Axon Pathfinding and Neuronal Migration

    PubMed Central

    Shakir, M. Afaq; Gill, Jason S.; Lundquist, Erik A.

    2006-01-01

    Many genes that affect axon pathfinding and cell migration have been identified. Mechanisms by which these genes and the molecules they encode interact with one another in pathways and networks to control developmental events are unclear. Rac GTPases, the cytoskeletal signaling molecule Enabled, and NIK kinase have all been implicated in regulating axon pathfinding and cell migration. Here we present evidence that, in Caenorhabditis elegans, three Rac GTPases, CED-10, RAC-2, and MIG-2, define three redundant pathways that each control axon pathfinding, and that the NIK kinase MIG-15 acts in each Rac pathway. Furthermore, we show that the Enabled molecule UNC-34 defines a fourth partially redundant pathway that acts in parallel to Rac/MIG-15 signaling in axon pathfinding. Enabled and the three Racs also act redundantly to mediate AQR and PQR neuronal cell migration. The Racs and UNC-34 Ena might all control the formation of actin-based protrusive structures (lamellipodia and filopodia) that mediate growth cone outgrowth and cell migration. MIG-15 does not act with the three Racs in execution of cell migration. Rather, MIG-15 affects direction of PQR neuronal migration, similar to UNC-40 and DPY-19, which control initial Q cell polarity, and Wnt signaling, which acts later to control Q cell-directed migration. MIG-2 Rac, which acts with CED-10 Rac, RAC-2 Rac, and UNC-34 Ena in axon pathfinding and cell migration, also acts with MIG-15 in PQR directional migration. PMID:16204220

  17. Modelling of the Saturnian Kilometric Radiation (SKR)

    NASA Astrophysics Data System (ADS)

    Cecconi, B.; Lamy, L.; Prangé, R.; Zarka, P.; Hess, S.; Clarke, J. T.; Nichols, J.

    2008-12-01

    The Saturnian Kilometric Radiation (SKR), discovered by the Voyager spacecraft in the 1980's, is observed quasi-continuously by Cassini since 2003. Study of 3 years of SKR observations by RPWS (Radio and Plasma Wave Science) revealed three recurrent features of SKR dynamic spectra : (i) discrete arcs, presumably caused by the anisotropy of the radio emission pattern combined to the observer's motion, (ii) an equatorial shadow zone around the planet (observed near perikrones) and (iii) signal extinctions at high northern latitudes. We model these features using the code PRES (Planetary Radio Emission Simulator) that assumes radio emissions to be generated via the Cyclotron Maser Instability for simulating observed dynamic spectra. We show that observed arc-like structures imply radio sources in partial (~90%) corotation, located on magnetic field lines of invariant latitude 70° to 75°, and emitting at oblique angle from the local magnetic field with a cone angle that varies with frequency. Then, based on the previously demonstrated conjugacy between UV and SKR sources, we successfully model the equatorial shadow zone as well as northern latitude SKR extinctions assuming time variable radio sources distributed along field lines with footprints along the daily UV oval measured from HST images.

  18. A Post-Pathfinder Evaluation of Areocentric Solar Coordinates with Improved Timing Recipes for Mars Seasonal/Diurnal Climate Studies

    NASA Technical Reports Server (NTRS)

    Allison, Michael; McEwen, Megan

    1999-01-01

    The accurate determination of the Mars pole vector derived from Pathfinder and Viking Lander radio data, together with the VSOP87 representation of planetary orbits, have been applied to a new evaluation of the right ascension of the "fictitious mean sun" (FMS) at Mars. With DELTA t (sub J2000) the elapsed time in days from the J2000 epoch (J.D.2451545.0 (sup TT), alpha FMS = 270 degrees.3863 + 0.52403840(degrees/d) (raised dot) DELTA T (sub j2000) - 4 x 10 (exp -13) (degrees/d (sup 2)) (raised dot) DELTA t (sup 2) (sub J2000) represents a best least-squares quadratic fit of the FMS, including aberration, to each instance of the four equinox and solstice passages for each of 134 Mars orbits spanning the calendar years 1874-2127. The implied tropical orbit period for Mars, 686.9726 (sup d), closely agrees with the recent evaluations. Together with the Pathfinder radio determination of the Mars sidereal rotation, the derived FMS rate corresponds to a mean solar day (or "sol") of 1.027491251 (sup d). The new FMS determination would serve to define the Mean Solar Time at Mars to the nearest tenth-second, according to historical conventions originally established for terrestrial time keeping, once the Mars prime meridian defined by the crater Airy-O is navigated to the same accuracy. For convenient reference to current epochs, 2000 Jan 06 00:00 UTC (= MJD 51549.000 (sup UTC)) corresponds to a coincidence of (alpha (sub FMS)) and the rotation angle of the crater Airy-O measured with respect to the Mars equinox (i.e. "mean solar midnight" on the planet's prime meridian), to within the current uncertainty of several seconds in the locational definition of the planet's cartographic grid. As a further result of the analysis, the consistently derived Mars obliquity of date is epsilon = 25 degrees.192 + 3.45 x l0 (exp -7)(degrees/d)(raised dot) DELTA t (sub J2000). An improved analytic recipe for the calculation of the solar areocentric longitude (L (sub s)) of Mars to an

  19. Simplicity and Typical Rank Results for Three-Way Arrays

    ERIC Educational Resources Information Center

    ten Berge, Jos M. F.

    2011-01-01

    Matrices can be diagonalized by singular vectors or, when they are symmetric, by eigenvectors. Pairs of square matrices often admit simultaneous diagonalization, and always admit block wise simultaneous diagonalization. Generalizing these possibilities to more than two (non-square) matrices leads to methods of simplifying three-way arrays by…

  20. Fiber developments at the Anglo-Australian Observatory for SPIRAL and AUSTRALIS

    NASA Astrophysics Data System (ADS)

    Lee, David; Taylor, Keith

    2000-08-01

    In this paper we discuss some of the recent developments with optical fibers at the Anglo-Australian Observatory. Firstly we will describe the upgrade to the SPIRAL integral field spectrograph for the Anglo-Australian Telescope. SPIRAL-B uses a crossed cylindrical microlens array to feed 512 optical fibers at F/5.5 providing a field of view of 22 by 11 arcseconds with 0.7 arcsecond spatial sampling. The performance of the fiber bundle, microlens array, and construction techniques will be described. We will also discus the development of prototype optical fiber switchyard as part of the AUSTRALIS concept study. The switchyard provides an 'optical bread' in the fiber, between the telescope and spectrograph, which allows coupling between fibers of different diameters and focal rations. A dichroic can also be incorporated into the switchyard to allow both optical and IR spectrographs to be fed simultaneously. Switchyards therefore provide much greater observing flexibility by increasing the number of possible instrument configurations. We will briefly discuss the merits of fiber switchyards and present the results of FRD and transmission test performed in the laboratory.

  1. Reversible ratchet effects for vortices in conformal pinning arrays

    DOE PAGES

    Reichhardt, Charles; Ray, Dipanjan; Reichhardt, Cynthia Jane Olson

    2015-05-04

    A conformal transformation of a uniform triangular pinning array produces a structure called a conformal crystal which preserves the sixfold ordering of the original lattice but contains a gradient in the pinning density. Here we use numerical simulations to show that vortices in type-II superconductors driven with an ac drive over gradient pinning arrays produce the most pronounced ratchet effect over a wide range of parameters for a conformal array, while square gradient or random gradient arrays with equivalent pinning densities give reduced ratchet effects. In the conformal array, the larger spacing of the pinning sites in the direction transversemore » to the ac drive permits easy funneling of interstitial vortices for one driving direction, producing the enhanced ratchet effect. In the square array, the transverse spacing between pinning sites is uniform, giving no asymmetry in the funneling of the vortices as the driving direction switches, while in the random array, there are numerous easy-flow channels present for either direction of drive. We find multiple ratchet reversals in the conformal arrays as a function of vortex density and ac amplitude, and correlate the features with a reversal in the vortex ordering, which is greater for motion in the ratchet direction. In conclusion, the enhanced conformal pinning ratchet effect can also be realized for colloidal particles moving over a conformal array, indicating the general usefulness of conformal structures for controlling the motion of particles.« less

  2. Ultralow-Background Large-Format Bolometer Arrays

    NASA Technical Reports Server (NTRS)

    Benford, Dominic; Chervenak, Jay; Irwin, Kent; Moseley, S. Harvey; Oegerle, William (Technical Monitor)

    2002-01-01

    In the coming decade, work will commence in earnest on large cryogenic far-infrared telescopes and interferometers. All such observatories - for example, SAFIR, SPIRIT, and SPECS - require large format, two dimensional arrays of close-packed detectors capable of reaching the fundamental limits imposed by the very low photon backgrounds present in deep space. In the near term, bolometer array architectures which permit 1000 pixels - perhaps sufficient for the next generation of space-based instruments - can be arrayed efficiently. Demonstrating the necessary performance, with Noise Equivalent Powers (NEPs) of order 10-20 W/square root of Hz, will be a hurdle in the coming years. Superconducting bolometer arrays are a promising technology for providing both the performance and the array size necessary. We discuss the requirements for future detector arrays in the far-infrared and submillimeter, describe the parameters of superconducting bolometer arrays able to meet these requirements, and detail the present and near future technology of superconducting bolometer arrays. Of particular note is the coming development of large format planar arrays with absorber-coupled and antenna-coupled bolometers.

  3. Advanced photovoltaic solar array design assessment

    NASA Technical Reports Server (NTRS)

    Stella, Paul; Scott-Monck, John

    1987-01-01

    The Advanced Photovoltaic Solar Array (APSA) program seeks to bring to flight readiness a solar array that effectively doubles the specific power of the Solar Array Flight Experiment/Solar Electric Propulsion (SAFE/SEP) design that was successfully demonstrated during the Shuttle 41-D mission. APSA is a critical intermediate milestone in the effort to demonstrate solar array technologies capable of 300 W/kg and 300 W/square m at beginning of life (BOL). It is not unreasonable to anticipate the development of solar array designs capable of 300 W/kg at BOL for operational power levels approx. greater than 25 kW sub e. It is also quite reasonable to expect that high performance solar arrays capable of providing at least 200 W/kg at end of life for most orbits now being considered by mission planners will be realized in the next decade.

  4. The Twin Peaks in 3-D, as Viewed by the Mars Pathfinder IMP Camera

    NASA Image and Video Library

    1997-11-04

    Twin Peaks are modest-size hills to the southwest of NASA Mars Pathfinder landing site. They were discovered on the first panoramas taken by the IMP camera on the 4th of July, 1997. 3D glasses are necessary to identify surface detail.

  5. Trio combines with dock to regulate Pak activity during photoreceptor axon pathfinding in Drosophila.

    PubMed

    Newsome, T P; Schmidt, S; Dietzl, G; Keleman, K; Asling, B; Debant, A; Dickson, B J

    2000-04-28

    Correct pathfinding by Drosophila photoreceptor axons requires recruitment of p21-activated kinase (Pak) to the membrane by the SH2-SH3 adaptor Dock. Here, we identify the guanine nucleotide exchange factor (GEF) Trio as another essential component in photoreceptor axon guidance. Regulated exchange activity of one of the two Trio GEF domains is critical for accurate pathfinding. This GEF domain activates Rac, which in turn activates Pak. Mutations in trio result in projection defects similar to those observed in both Pak and dock mutants, and trio interacts genetically with Rac, Pak, and dock. These data define a signaling pathway from Trio to Rac to Pak that links guidance receptors to the growth cone cytoskeleton. We propose that distinct signals transduced via Trio and Dock act combinatorially to activate Pak in spatially restricted domains within the growth cone, thereby controlling the direction of axon extension.

  6. Theoretical and experimental analysis of AlGaInP micro-LED array with square-circle anode

    NASA Astrophysics Data System (ADS)

    Tian, Chao; Wang, Weibiao; Liang, Jingqiu; Liang, Zhongzhu; Qin, Yuxin; Lv, Jinguang

    2015-04-01

    An array of 320 × 240 micro-light-emitting diodes (micro-LEDs) based on an AlGaInP epitaxial wafer and with a unit size of 100 µm×100 µm was designed and fabricated. The optimum width of the isolation groove between adjacent light-emitting units was determined based on a compromise between full isolation of each LED and maximization of the light emitting area, and was found to be 20 µm. The grooves were filled with a mixed Si granule-polyurethane composite medium, because this type of insulating material can reflect part of the emitted light from the sidewall to the window layer in each light-emitting unit, and could thus improve lighting output efficiency. The 10-µm-wide square-circle anode was designed to increase the light emitting area while simultaneously being simple to fabricate. The device current used was in the 0.42-1.06 mA range to guarantee internal quantum efficiency of more than 85%, with a corresponding voltage range of 2-2.3 V. The layered temperature distribution in a single unit was simulated under a drive voltage of 2.2 V, and the maximum device temperature was 341 K. The micro-opto-electro-mechanical systems (MOEMS) technology-based fabrication process, experimental images of the device and device test results are presented here.

  7. Theoretical and experimental analysis of AlGaInP micro-LED array with square-circle anode

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

    Tian, Chao; University of Chinese Academy of Sciences, Beijing 100049; Wang, Weibiao, E-mail: wangwbcn@163.com

    An array of 320 × 240 micro-light-emitting diodes (micro-LEDs) based on an AlGaInP epitaxial wafer and with a unit size of 100 µm×100 µm was designed and fabricated. The optimum width of the isolation groove between adjacent light-emitting units was determined based on a compromise between full isolation of each LED and maximization of the light emitting area, and was found to be 20 µm. The grooves were filled with a mixed Si granule-polyurethane composite medium, because this type of insulating material can reflect part of the emitted light from the sidewall to the window layer in each light-emitting unit,more » and could thus improve lighting output efficiency. The 10-µm-wide square-circle anode was designed to increase the light emitting area while simultaneously being simple to fabricate. The device current used was in the 0.42–1.06 mA range to guarantee internal quantum efficiency of more than 85%, with a corresponding voltage range of 2–2.3 V. The layered temperature distribution in a single unit was simulated under a drive voltage of 2.2 V, and the maximum device temperature was 341 K. The micro-opto-electro-mechanical systems (MOEMS) technology-based fabrication process, experimental images of the device and device test results are presented here.« less

  8. Do Integrated Children's Services Improve Children's Outcomes?: Evidence from England's Children's Trust Pathfinders

    ERIC Educational Resources Information Center

    O'Brien, Margaret; Bachmann, Max O.; Jones, Natalia R.; Reading, Richard; Thoburn, June; Husbands, Chris; Shreeve, Ann; Watson, Jacqueline

    2009-01-01

    Thirty-five children's trust pathfinders, local cross-sector partnerships, were introduced across England in 2003 to promote greater integration in children's services. Using administrative performance data, this paper tracks yearly trends in child service outputs and child well-being outcomes from 1997 to 2004 in these local areas, including the…

  9. Free-Suspension Residual Flexibility Testing of Space Station Pathfinder: Comparison to Fixed-Base Results

    NASA Technical Reports Server (NTRS)

    Tinker, Michael L.

    1998-01-01

    Application of the free-suspension residual flexibility modal test method to the International Space Station Pathfinder structure is described. The Pathfinder, a large structure of the general size and weight of Space Station module elements, was also tested in a large fixed-base fixture to simulate Shuttle Orbiter payload constraints. After correlation of the Pathfinder finite element model to residual flexibility test data, the model was coupled to a fixture model, and constrained modes and frequencies were compared to fixed-base test. modes. The residual flexibility model compared very favorably to results of the fixed-base test. This is the first known direct comparison of free-suspension residual flexibility and fixed-base test results for a large structure. The model correlation approach used by the author for residual flexibility data is presented. Frequency response functions (FRF) for the regions of the structure that interface with the environment (a test fixture or another structure) are shown to be the primary tools for model correlation that distinguish or characterize the residual flexibility approach. A number of critical issues related to use of the structure interface FRF for correlating the model are then identified and discussed, including (1) the requirement of prominent stiffness lines, (2) overcoming problems with measurement noise which makes the antiresonances or minima in the functions difficult to identify, and (3) the use of interface stiffness and lumped mass perturbations to bring the analytical responses into agreement with test data. It is shown that good comparison of analytical-to-experimental FRF is the key to obtaining good agreement of the residual flexibility values.

  10. Preliminary space station solar array structural design study

    NASA Technical Reports Server (NTRS)

    Dorsey, J. T.; Bush, H. G.; Mikulas, M. M., Jr.

    1984-01-01

    Structurally efficient ways to support the large solar arrays (3,716 square meters which are currently considered for space station use) are examined. An erectable truss concept is presented for the on orbit construction of winged solar arrays. The means for future growth, maintenance, and repair are integrally designed into this concept. Results from parametric studies, which highlight the physical and structural differences between various configuration options are presented. Consideration is given to both solar blanket and hard panel arrays.

  11. Preliminary space station solar array structural design study

    NASA Astrophysics Data System (ADS)

    Dorsey, J. T.; Bush, H. G.; Mikulas, M. M., Jr.

    Structurally efficient ways to support the large solar arrays (3,716 square meters which are currently considered for space station use) are examined. An erectable truss concept is presented for the on orbit construction of winged solar arrays. The means for future growth, maintenance, and repair are integrally designed into this concept. Results from parametric studies, which highlight the physical and structural differences between various configuration options are presented. Consideration is given to both solar blanket and hard panel arrays.

  12. Australian developments in marine science

    NASA Astrophysics Data System (ADS)

    Coffin, Millard F.

    2012-07-01

    Australia is an island nation with about two thirds of its jurisdiction underwater. On 25 May 2012, Australia instituted the Seas and Submerged Lands (Limits of Continental Shelf) Proclamation 2012, confirming areas of seabed where Australia has exclusive rights to explore and exploit marine resources. This proclamation follows recommendations by the Commission on the Limits of the Continental Shelf, a body established under the United Nations Convention on the Law of the Sea, confirming Australia's entitlement to extended continental shelf, i.e., that beyond 200 nautical miles from the coastline, of some 2.56 million square kilometers, excluding Australian Antarctic Territory [Symonds et al., 2009] (Figure 1a).

  13. Co-arrays in the Next Fortran Standard

    DOE PAGES

    Reid, John; Numrich, Robert W.

    2007-01-01

    The WG5 committee, at its meeting in Delft, May 2005, decided to include co-arrays in the next Fortran Standard. A Fortran program containing co-arrays is interpreted as if it were replicated a fixed number of times and all copies were executed asynchronously. Each copy has its own set of data objects and is called an image. The array syntax of Fortran is extended with additional trailing subscripts in square brackets to give a clear and straightforward representation of access to data on other images. References without square brackets are to local data, so code that can run independently is uncluttered.more » Any occurrence of square brackets is a warning about communication between images. The additional syntax requires support in the compiler, but it has been designed to be easy to implement and to give the compiler scope both to apply its optimizations within each image and to optimize the communication between images. The extension includes execution control statements for synchronizing images and intrinsic procedures to return the number of images, to return the index of the current image, and to perform collective operations. The paper does not attempt to describe the full details of the feature as it now appears in the draft of the new standard. Instead, we describe a subset and demonstrate the use of this subset with examples.« less

  14. Solar maximum: Solar array degradation

    NASA Technical Reports Server (NTRS)

    Miller, T.

    1985-01-01

    The 5-year in-orbit power degradation of the silicon solar array aboard the Solar Maximum Satellite was evaluated. This was the first spacecraft to use Teflon R FEP as a coverglass adhesive, thus avoiding the necessity of an ultraviolet filter. The peak power tracking mode of the power regulator unit was employed to ensure consistent maximum power comparisons. Telemetry was normalized to account for the effects of illumination intensity, charged particle irradiation dosage, and solar array temperature. Reference conditions of 1.0 solar constant at air mass zero and 301 K (28 C) were used as a basis for normalization. Beginning-of-life array power was 2230 watts. Currently, the array output is 1830 watts. This corresponds to a 16 percent loss in array performance over 5 years. Comparison of Solar Maximum Telemetry and predicted power levels indicate that array output is 2 percent less than predictions based on an annual 1.0 MeV equivalent election fluence of 2.34 x ten to the 13th power square centimeters space environment.

  15. The nightmare scenario: measuring the stochastic gravitational wave background from stalling massive black hole binaries with pulsar timing arrays

    NASA Astrophysics Data System (ADS)

    Dvorkin, Irina; Barausse, Enrico

    2017-10-01

    Massive black hole binaries, formed when galaxies merge, are among the primary sources of gravitational waves targeted by ongoing pulsar timing array (PTA) experiments and the upcoming space-based Laser Interferometer Space Antenna (LISA) interferometer. However, their formation and merger rates are still highly uncertain. Recent upper limits on the stochastic gravitational wave background obtained by PTAs are starting to be in marginal tension with theoretical models for the pairing and orbital evolution of these systems. This tension can be resolved by assuming that these binaries are more eccentric or interact more strongly with the environment (gas and stars) than expected, or by accounting for possible selection biases in the construction of the theoretical models. However, another (pessimistic) possibility is that these binaries do not merge at all, but stall at large (˜pc) separations. We explore this extreme scenario by using a semi-analytic galaxy formation model including massive black holes (isolated and in binaries), and show that future generations of PTAs will detect the stochastic gravitational wave background from the massive black hole binary population within 10-15 yr of observations, even in the `nightmare scenario' in which all binaries stall at the hardening radius. Moreover, we argue that this scenario is too pessimistic, because our model predicts the existence of a subpopulation of binaries with small mass ratios (q ≲ 10-3) that should merge within a Hubble time simply as a result of gravitational wave emission. This subpopulation will be observable with large signal-to-noise ratios by future PTAs thanks to next-generation radio telescopes such as Square Kilometre Array or Five-hundred-meter Aperture Spherical Telescope, and possibly by LISA.

  16. Automated Array Assembly, Phase 2

    NASA Technical Reports Server (NTRS)

    Carbajal, B. G.

    1979-01-01

    The Automated Array Assembly Task, Phase 2 of the Low Cost Silicon Solar Array Project is a process development task. The contract provides for the fabrication of modules from large area tandem junction cells (TJC). During this quarter, effort was focused on the design of a large area, approximately 36 sq cm, TJC and process verification runs. The large area TJC design was optimized for minimum I squared R power losses. In the TJM activity, the cell-module interfaces were defined, module substrates were formed and heat treated and clad metal interconnect strips were fabricated.

  17. Statechart Analysis with Symbolic PathFinder

    NASA Technical Reports Server (NTRS)

    Pasareanu, Corina S.

    2012-01-01

    We report here on our on-going work that addresses the automated analysis and test case generation for software systems modeled using multiple Statechart formalisms. The work is motivated by large programs such as NASA Exploration, that involve multiple systems that interact via safety-critical protocols and are designed with different Statechart variants. To verify these safety-critical systems, we have developed Polyglot, a framework for modeling and analysis of model-based software written using different Statechart formalisms. Polyglot uses a common intermediate representation with customizable Statechart semantics and leverages the analysis and test generation capabilities of the Symbolic PathFinder tool. Polyglot is used as follows: First, the structure of the Statechart model (expressed in Matlab Stateflow or Rational Rhapsody) is translated into a common intermediate representation (IR). The IR is then translated into Java code that represents the structure of the model. The semantics are provided as "pluggable" modules.

  18. Numerical investigation of flow past 17-cylinder array of square cylinders

    NASA Astrophysics Data System (ADS)

    Shams-ul-Islam, Nazeer, Ghazala; Ying, Zhou Chao

    2018-06-01

    In this work, flow past 17-cylinder array is simulated using the two-dimensional lattice Boltzmann method. Effect of gap spacings (0.5 ≤ gx* ≤ 3, 0.5 ≤ gy* ≤ 3) and Reynolds number (Re = 75 - 150) is analyzed in details. Results are presented in the form of vorticity contours plots, time-histories of drag and lift coefficients and power spectrum of lift coefficient. Six distinct flow regimes are identified for different gap spacings and Reynolds numbers: steady flow regime, single bluff body flow regime, non-fully developed flow regime, chaotic flow regime, quasi-periodic-I flow regime and quasi-periodic-II flow regime. Chaotic flow regime is the mostly observed flow regime while the single bluff body flow regime rarely occurs for this configuration. It is observed that drag force along each cylinder in 17-cylinder array decreases in the streamwise direction for fixed Reynold number and gap spacing. C1 and C2 cylinders experience the maximum drag at small gap spacing and Reynolds number. Also the Reynolds number is found to be more effective on flow characteristics as compared to gap spacings.

  19. Low Frequency Extensions of the Saturn Kilometric Radiation as a Proxy for Magnetospheric Dynamics.

    NASA Astrophysics Data System (ADS)

    Reed, J.; Jackman, C. M.; Whiter, D. K.; Kurth, W. S.; Lamy, L.

    2016-12-01

    Saturn Kilometric Radiation (SKR) is a radio emission formed via the cyclotron maser instability on field aligned currents near the auroral regions of Saturn. The SKR has been found to respond to both internal and external driving, and to be linked to both solar wind compressions and magnetotail reconnection events. The radio emission is remotely sensed quasi-continuously and therefore offers the potential to be used as a proxy for magnetospheric activity when the spacecraft is not in an ideal viewing region for observing signatures of reconnection. In this work we use data taken by the Cassini magnetometer and radio and plasma wave sensor while Cassini was executing its deepest tail orbits in 2006. We characterise the behaviour of the SKR over this period and develop an automatic method for finding low frequency extensions (LFE), where the SKR emission extends down to lower frequencies below the main band. LFEs have been shown to occur in response to reconnection at Saturn (Jackman et al, 2009) and their appearance in Earth's analogous Auroral Kilometric Radiation (AKR) has been shown to coincide with substorm onset (e.g. Morioka et al, 2007). Using a new catalogue of LFEs we discuss their correlation with known tail reconnection events and solar wind shocks (as inferred from the use of propagated solar wind models). We also look at their properties such as length and recurrence rate, as well as their relationship to the planetary periodicities.

  20. Is it feasible to pool funds for local children's services in England? Evidence from the national evaluation of children's trust pathfinders.

    PubMed

    Lorgelly, Paula; Bachmann, Max; Shreeve, Ann; Reading, Richard; Thorburn, June; Mugford, Miranda; O'Brien, Margaret; Husbands, Chris

    2009-01-01

    To describe how funds were pooled or otherwise jointly managed by National Health Service (NHS) primary care trusts and local authorities in England. To compare expenditure on local children's services by health, education and social services. We conducted a questionnaire survey of all 35 children's trust pathfinders, six months after they were launched, with a follow-up at 2.5 years. We also undertook an in-depth analysis of local authorities and primary care trusts, within eight pathfinder areas and three non-pathfinder areas, whereby we compared expenditure on children's services, interviewed managers and professionals and examined financial documents. Local authorities and NHS trusts coordinated expenditure in various ways, most commonly through informal agreements and aligning budgets but also by formally pooling budgets. The latter were usually for selected services such as child and adolescent mental health services, though four children's trusts pathfinders pooled (or aligned) their budgets for all children's services. Total expenditure per child was greatest for education, lowest for social services and intermediate for health. However, it was difficult to quantify education expenditure on children with health and social care needs, and health care expenditure on children. Sharing money for local children's services requires shared objectives, trust, and legal and accounting expertise. Several different mechanisms are permitted and many are feasible but programme budgeting for children's services could make them more effective.

  1. Results from the Telescope Array Experiment

    NASA Astrophysics Data System (ADS)

    Jui, Charles C. H.; Telescope Array Collaboration

    2016-04-01

    The Telescope Array (TA) is the largest ultrahigh energy cosmic ray detector in the northern hemisphere. The experiment consists of three fluorescence stations viewing the air space over a surface array of 507 scintillation counters deployed over 700 square kilometers. TA has been in operation since 2008. The most recent results from TA, including that of composition studies and search for arrival direction anisotropy, will be presented. We will also report on the progress of the new TA low energy extension (TALE).

  2. Charge-Induced Force Noise on Free-Falling Test Masses: Results from LISA Pathfinder

    NASA Astrophysics Data System (ADS)

    Armano, M.; Audley, H.; Auger, G.; Baird, J. T.; Binetruy, P.; Born, M.; Bortoluzzi, D.; Brandt, N.; Bursi, A.; Caleno, M.; Cavalleri, A.; Cesarini, A.; Cruise, M.; Danzmann, K.; de Deus Silva, M.; Diepholz, I.; Dolesi, R.; Dunbar, N.; Ferraioli, L.; Ferroni, V.; Fitzsimons, E. D.; Flatscher, R.; Freschi, M.; Gallegos, J.; García Marirrodriga, C.; Gerndt, R.; Gesa, L.; Gibert, F.; Giardini, D.; Giusteri, R.; Grimani, C.; Grzymisch, J.; Harrison, I.; Heinzel, G.; Hewitson, M.; Hollington, D.; Hueller, M.; Huesler, J.; Inchauspé, H.; Jennrich, O.; Jetzer, P.; Johlander, B.; Karnesis, N.; Kaune, B.; Killow, C. J.; Korsakova, N.; Lloro, I.; Liu, L.; López-Zaragoza, J. P.; Maarschalkerweerd, R.; Madden, S.; Mance, D.; Martín, V.; Martin-Polo, L.; Martino, J.; Martin-Porqueras, F.; Mateos, I.; McNamara, P. W.; Mendes, J.; Mendes, L.; Moroni, A.; Nofrarias, M.; Paczkowski, S.; Perreur-Lloyd, M.; Petiteau, A.; Pivato, P.; Plagnol, E.; Prat, P.; Ragnit, U.; Ramos-Castro, J.; Reiche, J.; Romera Perez, J. A.; Robertson, D. I.; Rozemeijer, H.; Rivas, F.; Russano, G.; Sarra, P.; Schleicher, A.; Slutsky, J.; Sopuerta, C.; Sumner, T. J.; Texier, D.; Thorpe, J. I.; Trenkel, C.; Vetrugno, D.; Vitale, S.; Wanner, G.; Ward, H.; Wass, P. J.; Wealthy, D.; Weber, W. J.; Wittchen, A.; Zanoni, C.; Ziegler, T.; Zweifel, P.; LISA Pathfinder Collaboration

    2017-04-01

    We report on electrostatic measurements made on board the European Space Agency mission LISA Pathfinder. Detailed measurements of the charge-induced electrostatic forces exerted on free-falling test masses (TMs) inside the capacitive gravitational reference sensor are the first made in a relevant environment for a space-based gravitational wave detector. Employing a combination of charge control and electric-field compensation, we show that the level of charge-induced acceleration noise on a single TM can be maintained at a level close to 1.0 fm s-2 Hz-1 /2 across the 0.1-100 mHz frequency band that is crucial to an observatory such as the Laser Interferometer Space Antenna (LISA). Using dedicated measurements that detect these effects in the differential acceleration between the two test masses, we resolve the stochastic nature of the TM charge buildup due to interplanetary cosmic rays and the TM charge-to-force coupling through stray electric fields in the sensor. All our measurements are in good agreement with predictions based on a relatively simple electrostatic model of the LISA Pathfinder instrument.

  3. Pathfinder Atomic Power Plant Nozzle Galling Test, Final Report

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

    None, None

    1961-12-29

    Galling tests of 304, 17-4PH, and chrome-plated 304 stainless-steel nozzles with 304 stainless-steel sleeves were conducted at Pathflnder reactor conditions of 480 deg F, 600 psig. A horizontal force was imposed on the sleeve with the nozzle inserted; and the nozzle was moved axially to determine galling tendencies. Galling was produced on both the 304 and 17-4PH stainless-steel nozzles. The chrome-plated 304-stainless-steel nozzles were cycled numerous times without galling. On the basis of these tests, chrome-plated 304-stainless- steel is the material selected for the Pathfinder boiler fuel-element nozzle.

  4. Charge Management in LISA Pathfinder: The Continuous Discharging Experiment

    NASA Astrophysics Data System (ADS)

    Ewing, Becca Elizabeth

    2018-01-01

    Test mass charging is a significant source of excess force and force noise in LISA Pathfinder (LPF). The planned design scheme for mitigation of charge induced force noise in LISA is a continuous discharge by UV light illumination. We report on analysis of a charge management experiment on-board LPF conducted during December 2016. We discuss the measurement of test mass charging noise with and without continuous UV illumination, in addition to the dynamic response in the continuous discharge scheme. Results of the continuous discharge system will be discussed for their application to operating LISA with lower test mass charge.

  5. Atmospheric Profiles of Carbon Dioxide Obtained with a UAS: Constraints on Square Kilometre Scale Carbon Budgets

    NASA Astrophysics Data System (ADS)

    Kunz, M.; Lavric, J. V.; Grant, R. H.; Gerbig, C.; Heimann, M.; Flatt, J. E.; Zeeman, M. J.; Wolf, B.

    2016-12-01

    The exchange of carbon between biosphere and atmosphere is a topic of high interest, particularly because the magnitude of biospheric climate feedback is uncertain. Soil chambers and eddy covariance systems, the traditional tools for the measurement of exchange fluxes, are subject to inherent limitations: chambers cover only small areas of typically less than on square meter, and eddy covariance is not applicable under very low wind conditions. Complementary methods can help to deal with these limitations and provide more confidence in up-scaling. During the ScaleX 2016 campaign an ecosystem was studied with a combination of multiple measurement approaches, including soil chambers, an eddy covariance station, a weather station, quasi-continuous CO2 measurements on a 10 m tower, multiple UAS with different sensors and remote sensing of temperature, humidity and wind profiles. The campaign took place at Fendt in Southern Germany on a flat valley floor covered by grass. We deployed COCAP, a compact carbon dioxide analyser for airborne platforms developed at the Max Planck Institute for Biogeochemistry in Jena, on a commercial multicopter (DJI S1000). COCAP measures carbon dioxide dry air mole fraction to an accuracy of 2 ppm as well as ambient pressure, temperature and relative humidity. At a total mass of 1 kg it contains a GPS receiver, on-board data logging capabilities and a radio transmitter which allows for real-time data visualisation on a ground station computer. In consecutive vertical profile measurements at night-time, reaching up to a maximum height of 150 m, we see a strong build-up of CO2 close to the ground which we attribute to exchange fluxes from the surface into the atmosphere that are trapped below a nocturnal inversion. We estimate these fluxes from the change in observed column amount of CO2 over time and compare our results to other methods. Challenges in the measurement and data analysis as well as the influence of wind, rotor downwash and

  6. Pathfinder. Volume 8, Number 3, May/June 2010. Technology - Rendering an Ever-Clearer Picture

    DTIC Science & Technology

    2010-06-01

    Agency,Office of Corporate Communications,4600 Sangamore Road, Mail Stop D-54,Bethesda,MD, 20816 -5003 8. PERFORMING ORGANIZATION REPORT NUMBER 9...Bethesda, MD 20816 -5003 Telephone: (301) 227-7388, DSN 287-7388 E-mail: pathfinder@nga.mil Director Vice Adm. Robert B. Murrett, U.S. Navy Deputy

  7. Infrared-Bolometer Arrays with Reflective Backshorts

    NASA Technical Reports Server (NTRS)

    Miller, Timothy M.; Abrahams, John; Allen, Christine A.

    2011-01-01

    Integrated circuits that incorporate square arrays of superconducting-transition- edge bolometers with optically reflective backshorts are being developed for use in image sensors in the spectral range from far infrared to millimeter wavelengths. To maximize the optical efficiency (and, thus, sensitivity) of such a sensor at a specific wavelength, resonant optical structures are created by placing the backshorts at a quarter wavelength behind the bolometer plane. The bolometer and backshort arrays are fabricated separately, then integrated to form a single unit denoted a backshort-under-grid (BUG) bolometer array. In a subsequent fabrication step, the BUG bolometer array is connected, by use of single-sided indium bump bonding, to a readout device that comprises mostly a superconducting quantum interference device (SQUID) multiplexer circuit. The resulting sensor unit comprising the BUG bolometer array and the readout device is operated at a temperature below 1 K. The concept of increasing optical efficiency by use of backshorts at a quarter wavelength behind the bolometers is not new. Instead, the novelty of the present development lies mainly in several features of the design of the BUG bolometer array and the fabrication sequence used to implement the design. Prior to joining with the backshort array, the bolometer array comprises, more specifically, a square grid of free-standing molybdenum/gold superconducting-transition-edge bolometer elements on a 1.4- m-thick top layer of silicon that is part of a silicon support frame made from a silicon-on-insulator wafer. The backshort array is fabricated separately as a frame structure that includes support beams and contains a correspond - ing grid of optically reflective patches on a single-crystal silicon substrate. The process used to fabricate the bolometer array includes standard patterning and etching steps that result in the formation of deep notches in the silicon support frame. These notches are designed to

  8. Contrasts in lithospheric structure within the Australian craton—insights from surface wave tomography

    NASA Astrophysics Data System (ADS)

    Fishwick, S.; Kennett, B. L. N.; Reading, A. M.

    2005-03-01

    Contrasts in the seismic structure of the lithosphere within and between elements of the Australian Craton are imaged using surface wave tomography. New data from the WACRATON and TIGGER experiments are integrated with re-processed data from previous temporary deployments of broad-band seismometers and permanent seismic stations. The much improved path coverage in critical regions allows an interpretation of structures in the west of Australia, and a detailed comparison between different cratonic regions. Improvements to the waveform inversion procedure and a new multi-scale tomographic method increase the reliability of the tomographic images. In the shallowest part of the model (75 km) a region of lowered velocity is imaged beneath central Australia, and confirmed by the delayed arrival times of body waves for short paths. Within the cratonic lithosphere there is clearly structure at scale lengths of a few hundred kilometres; resolution tests indicate that path coverage within the continent is sufficient to reveal features of this size in the upper part of our model. In Western Australia, differences are seen beneath and within the Archaean cratons: at depths greater than 150 km faster velocities are imaged beneath the Yilgarn Craton than beneath the Pilbara Craton. In the complex North Australian Craton a fast wavespeed anomaly continuing to at least 250 km is observed below parts of the craton, suggesting the possibility of Archaean lithosphere underlying areas of dominantly Proterozoic surface geology.

  9. Mars Pathfinder Landing Site Workshop 2: Characteristics of the Ares Vallis Region and Field Trips in the Channeled Scabland, Washington

    NASA Technical Reports Server (NTRS)

    Golombek, M. P. (Editor); Edgett, K. S. (Editor); Rice, J. W. , Jr. (Editor)

    1995-01-01

    Mars Pathfinder will place a single lander on the surface of Mars on July 4, 1997, following a December 1996 launch. As a result of the very successful first Mars Pathfinder Landing Site Workshop, the project has selected the Ares Vallis outflow channel in Chryse Planitia as the landing site. This location is where a large catastrophic outflow channel debouches into the northern lowlands. A second workshop and series of field trips, entitled Mars Pathfinder Landing Site Workshop 2: Characteristics of the Ares Vallis Region and Field Trips in the Channeled Scabland, Washington, were held in Spokane and Moses Lake, Washington. The purpose of the workshop was to provide a focus for learning as much as possible about the Ares Vallis region on Mars before landing there. The rationale is that the more that can be learned about the general area prior to landing, the better scientists will be able interpret the observations made by the lander and rover and place them in the proper geologic context. The field trip included overflights and surface investigations of the Channeled Scabland (an Earth analog for the martian catastrophic outflow channels), focusing on areas particularly analogous to Ares Vallis and the landing site. The overflights were essential for placing the enormous erosional and depositional features of the Channeled Scabland into proper three-dimensional context. The field trips were a joint educational outreach activity involving K-12 science educators, Mars Pathfinder scientists and engineers, and interested scientists from the Mars scientific community. Part 1 of the technical report on this workshop includes a description of the Mars Pathfinder mission, abstracts accepted for presentation at the workshop, an introduction to the Channeled Scabland, and field trip guides for the overflight and two field trips. This part, Part 2, includes the program for the workshop, summaries of the workshop technical sessions, a summary of the field trips and ensuing

  10. Graeco-Latin Squares and a Mistaken Conjecture of Euler

    ERIC Educational Resources Information Center

    Klyve, Dominic; Stemkoski, Leo

    2006-01-01

    A Graeco-Latin square of order "n" is an "n[superscript x]n" array whose entries are the "n"[superscript 2] ordered pairs of numbers from 1 to "n", and in each row and each column the first elements of the ordered pairs are all different, as are the second elements. This article traces the history of the results that came out of work on a false…

  11. Longitudinal Laminar Flow Between Cylinders Arranged in Regular Array

    NASA Technical Reports Server (NTRS)

    Sparrow, E. M.; Loeffler, A. L., Jr.

    1959-01-01

    The increasing complexity of heat transfer and process situations which involve fluid flow has demanded the frequent use of flow passages of unusual geometrical configuration. The present investigation is concerned with one such novel configuration, namely the longitudinal flow between solid cylindrical rods which are arranged in regular array. A schematic diagram of the situation under study. The rods may be located either in triangular or square array. The flow will be taken to be laminar and fully developed. The aim of this analysis is to determine the pressure drop, shear stress, and velocity-distribution characteristics of the system. The starting point of this study is the basic law of momentum conservation. The resulting differential equation has been solved in an approximate, but almost exact, manner by the use of truncated trigonometric series. Results are obtained over a wide range of porosity values for both the triangular and square arrays. Heat transfer has not been considered. The configuration under investigation has potential application in compact heat exchangers for nuclear reactors and other situations. Further the results should also be of interest in the theory of flow through unconsolidated porous beds (ia, 9a). The only related analytical work known to the authors is that of Emersleben (S), who considered only the square array. His rather involved solution, based on complex zeta functions, appears to be valid only at high porosities. Experiments covering a porosity range of 0.093 to 0.984 have been made by Sullivan (4) using parallel-oriented fibers, most of the tests being for fibers in random array. These previous investigations will be compared with the present theory in a later section.

  12. Analysis of entry accelerometer data: A case study of Mars Pathfinder

    NASA Astrophysics Data System (ADS)

    Withers, Paul; Towner, M. C.; Hathi, B.; Zarnecki, J. C.

    2003-08-01

    Accelerometers are regularly flown on atmosphere-entering spacecraft. Using their measurements, the spacecraft trajectory and the vertical structure of density, pressure, and temperature in the atmosphere through which it descends can be calculated. We review the general procedures for trajectory and atmospheric structure reconstruction and outline them here in detail. We discuss which physical properties are important in atmospheric entry, instead of working exclusively with the dimensionless numbers of fluid dynamics. Integration of the equations of motion governing the spacecraft trajectory is carried out in a novel and general formulation. This does not require an axisymmetric gravitational field or many of the other assumptions that are present in the literature. We discuss four techniques - head-on, drag-only, acceleration ratios, and gyroscopes - for constraining spacecraft attitude, which is the critical issue in the trajectory reconstruction. The head-on technique uses an approximate magnitude and direction for the aerodynamic acceleration, whereas the drag-only technique uses the correct magnitude and an approximate direction. The acceleration ratios technique uses the correct magnitude and an indirect way of finding the correct direction and the gyroscopes technique uses the correct magnitude and a direct way of finding the correct direction. The head-on and drag-only techniques are easy to implement and require little additional information. The acceleration ratios technique requires extensive and expensive aerodynamic modelling. The gyroscopes technique requires additional onboard instrumentation. The effects of errors are briefly addressed. Our implementations of these trajectory reconstruction procedures have been verified on the Mars Pathfinder dataset. We find inconsistencies within the published work of the Pathfinder science team, and in the PDS archive itself, relating to the entry state of the spacecraft. Our atmospheric structure

  13. The relationships between organizational and individual variables to on-the-job driver accidents and accident-free kilometres.

    PubMed

    Caird, J K; Kline, T J

    2004-12-01

    Highway fatalities are the leading cause of fatal work injuries in the US, accounting for approximately 1 in 4 of the 5900 job-related deaths during 2001. The present study focused on the contribution of organizational factors and driver behaviours to on-the-job driving accidents in a large Western Canadian corporation. A structural equation modelling (SEM) approach was used which allows researchers to test a complex set of relationships within a global theoretical framework. A number of scales were used to assess organizational support, driver errors, and driver behaviours. The sample of professional drivers that participated allowed the recording of on-the-job accidents and accident-free kilometres from their personnel files. The pattern of relationships in the fitted model, after controlling for exposure and social desirability, provides insight into the role of organizational support, planning, environment adaptations, fatigue, speed, errors and moving citations to on-the-job accidents and accident-free kilometres. For example, organizational support affected the capacity to plan. Time to plan work-related driving was found to predict accidents, fatigue and adaptations to the environment. Other interesting model paths, SEM limitations, future research and recommendations are elaborated.

  14. Electrostatic Charging of the Pathfinder Rover

    NASA Technical Reports Server (NTRS)

    Siebert, Mark W.; Kolecki, Joseph C.

    1996-01-01

    The Mars Pathfinder mission will send a lander and a rover to the martian surface. Because of the extremely dry conditions on Mars, electrostatic charging of the rover is expected to occur as it moves about. Charge accumulation may result in high electrical potentials and discharge through the martian atmosphere. Such discharge could interfere with the operation of electrical elements on the rover. A strategy was sought to mitigate this charge accumulation as a precautionary measure. Ground tests were performed to demonstrate charging in laboratory conditions simulating the surface conditions expected at Mars. Tests showed that a rover wheel, driven at typical rover speeds, will accumulate electrical charge and develop significant electrical potentials (average observed, 110 volts). Measurements were made of wheel electrical potential, and wheel capacitance. From these quantities, the amount of absolute charge was estimated. An engineering solution was developed and recommended to mitigate charge accumulation. That solution has been implemented on the actual rover.

  15. Actuation crosstalk in free-falling systems: Torsion pendulum results for the engineering model of the LISA pathfinder gravitational reference sensor

    NASA Astrophysics Data System (ADS)

    Bassan, M.; Cavalleri, A.; De Laurentis, M.; De Marchi, F.; De Rosa, R.; Di Fiore, L.; Dolesi, R.; Finetti, N.; Garufi, F.; Grado, A.; Hueller, M.; Marconi, L.; Milano, L.; Minenkov, Y.; Pucacco, G.; Stanga, R.; Vetrugno, D.; Visco, M.; Vitale, S.; Weber, W. J.

    2018-01-01

    In this paper we report on measurements on actuation crosstalk, relevant to the gravitational reference sensors for LISA Pathfinder and LISA. In these sensors, a Test Mass (TM) falls freely within a system of electrodes used for readout and control. These measurements were carried out on ground with a double torsion pendulum that allowed us to estimate both the torque injected into the sensor when a control force is applied and, conversely, the force leaking into the translational degree of freedom due to the applied torque.The values measured on our apparatus (the engineering model of the LISA Pathfinder sensor) agree to within 0.2% (over a maximum measured crosstalk of 1%) with predictions of a mathematical model when measuring force to torque crosstalk, while it is somewhat larger than expected (up to 3.5%) when measuring torque to force crosstalk. However, the values in the relevant range, i.e. when the TM is well centered ( ± 10 μm) in the sensor, remain smaller than 0.2%, satisfying the LISA Pathfinder requirements.

  16. Notochord alters the permissiveness of myotome for pathfinding by an identified motoneuron in embryonic zebrafish.

    PubMed

    Beattie, C E; Eisen, J S

    1997-02-01

    During zebrafish development, identified motoneurons innervate cell-specific regions of each trunk myotome. One motoneuron, CaP, extends an axon along the medial surface of the ventral myotome. To learn how this pathway is established during development, the CaP axon was used as an assay to ask whether other regions of the myotome were permissive for normal CaP pathfinding. Native myotomes were replaced with donor myotomes in normal or reversed dorsoventral orientations and CaP pathfinding was assayed. Ventral myotomes were permissive for CaP axons, even when they were taken from older embryos, suggesting that the CaP pathway remained present on ventral myotome throughout development. Dorsal myotomes from young embryos were also permissive for CaP axons, however, older dorsal myotomes were non-permissive, showing that permissiveness of dorsal myotome for normal CaP pathfinding diminished over time. This process appears to depend on signals from the embryo, since dorsal myotomes matured in vitro remained permissive for CaP axons. Genetic mosaics between wild-type and floating head mutant embryos revealed notochord involvement in dorsal myotome change of permissiveness. Dorsal and ventral myotomes from both younger and older floating head mutant embryos were permissive for CaP axons. These data suggest that initially both dorsal and ventral myotomes are permissive for CaP axons but as development proceeds, there is a notochord-dependent decrease in permissiveness of dorsal myotome for CaP axonal outgrowth. This change participates in restricting the CaP pathway to the ventral myotome and thus to neuromuscular specificity.

  17. Optical Bench Interferometer - From LISA Pathfinder to NGO/eLISA

    NASA Astrophysics Data System (ADS)

    Taylor, A.; d'Arcio, L.; Bogenstahl, J.; Danzmann, K.; Diekmann, C.; Fitzsimons, E. D.; Gerberding, O.; Heinzel, G.; Hennig, J.-S.; Hogenhuis, H.; Killow, C. J.; Lieser, M.; Lucarelli, S.; Nikolov, S.; Perreur-Lloyd, M.; Pijnenburg, J.; Robertson, D. I.; Sohmer, A.; Tröbs, M.; Ward, H.; Weise, D.

    2013-01-01

    We present a short summary of some optical bench construction and alignment developments that build on experience gained during the LISA Pathfinder optical bench assembly. These include evolved fibre injectors, a new beam vector measurement system, and thermally stable mounting hardware. The beam vector measurement techniques allow the alignment of beams to targets with absolute accuracy of a few microns and 20 microradians. We also describe a newly designed ultra-low-return beam dump that is expected to be a crucial element in the control of ghost beams on the optical benches.

  18. Techniques for identifying dust devils in mars pathfinder images

    USGS Publications Warehouse

    Metzger, S.M.; Carr, J.R.; Johnson, J. R.; Parker, T.J.; Lemmon, M.T.

    2000-01-01

    Image processing methods used to identify and enhance dust devil features imaged by IMP (Imager for Mars Pathfinder) are reviewed. Spectral differences, visible red minus visible blue, were used for initial dust devil searches, driven by the observation that Martian dust has high red and low blue reflectance. The Martian sky proved to be more heavily dust-laden than pre-Pathfinder predictions, based on analysis of images from the Hubble Space Telescope. As a result, these initial spectral difference methods failed to contrast dust devils with background dust haze. Imager artifacts (dust motes on the camera lens, flat-field effects caused by imperfections in the CCD, and projection onto a flat sensor plane by a convex lens) further impeded the ability to resolve subtle dust devil features. Consequently, reference images containing sky with a minimal horizon were first subtracted from each spectral filter image to remove camera artifacts and reduce the background dust haze signal. Once the sky-flat preprocessing step was completed, the red-minus-blue spectral difference scheme was attempted again. Dust devils then were successfully identified as bright plumes. False-color ratios using calibrated IMP images were found useful for visualizing dust plumes, verifying initial discoveries as vortex-like features. Enhancement of monochromatic (especially blue filter) images revealed dust devils as silhouettes against brighter background sky. Experiments with principal components transformation identified dust devils in raw, uncalibrated IMP images and further showed relative movement of dust devils across the Martian surface. A variety of methods therefore served qualitative and quantitative goals for dust plume identification and analysis in an environment where such features are obscure.

  19. Constellations Solar Array Design, Industrialization And In-Flight Results

    NASA Astrophysics Data System (ADS)

    Combet, Yannick; Clapper, Paul

    2011-10-01

    Constellations has become a recurring opportunities in Thales Alenia Space since 3 majors programs had been awarded: Globalstar was the pathfinder with 48 flight sets followed by O3b with 8 an the latest is Iridium Next with 81 models. For these 3 programs, the Solar Array is fully developed, validated and produced by Thales Alenia Space with major subcontractors. This new segment of the activity leads to new development, design and industrialization approaches. This paper describes the Solar Array design and the alternative to current approach build and applied with the following drivers: - the low recurring cost and mass of the flight hardware, with particular attention on the Solar Array, - high robustness for system integration and in-orbit operations, - a long mission duration (typically 15 years in LEO) leading to take into account high number of thermal cycles (60 to 72.000 cycles), - new production concept with strict schedule management, - design segmented in subassemblies to reduce the integration time as well as a improved trouble shooting management, - delivery rate up to 1 wing per week and after learning curve effect, a integration duration divided by 3 compared to current production, - a delivery of a qualified PFM solar array in 22 months including the design to producibility constrains, This demanding requirement for delivery scheme and cost target did not jeopardize the requirements and standards for space application. After a brief description of the way the main drivers have been considered, the paper presents the main features and performances of the subsystem and shows the main validation test results. The first launch was successful in October 2010 and the first in-orbit results are presented.

  20. Wheel Abrasion Experiment Metals Selection for Mars Pathfinder Mission

    NASA Technical Reports Server (NTRS)

    Hepp, Aloysius F.; Fatemi, Navid S.; Wilt, David M.; Ferguson, Dale C.; Hoffman, Richard; Hill, Maria M.; Kaloyeros, Alain E.

    1996-01-01

    A series of metals was examined for suitability for the Wheel Abrasion Experiment, one of ten microrover experiments of the Mars Pathfinder Mission. The seven candidate metals were: Ag, Al, Au, Cu, Ni, Pt, and W. Thin films of candidate metals from 0.1 to 1.0 micrometer thick were deposited on black anodized aluminum coupons by e-beam and resistive evaporation and chemical vapor deposition. Optical, corrosion, abrasion, and adhesion criteria were used to select Al, Ni, and Pt. A description is given of the deposition and testing of thin films, followed by a presentation of experimental data and a brief discussion of follow-on testing and flight qualification.

  1. Promising Results from Three NASA SBIR Solar Array Technology Development Programs

    NASA Technical Reports Server (NTRS)

    Eskenazi, Mike; White, Steve; Spence, Brian; Douglas, Mark; Glick, Mike; Pavlick, Ariel; Murphy, David; O'Neill, Mark; McDanal, A. J.; Piszczor, Michael

    2005-01-01

    Results from three NASA SBIR solar array technology programs are presented. The programs discussed are: 1) Thin Film Photovoltaic UltraFlex Solar Array; 2) Low Cost/Mass Electrostatically Clean Solar Array (ESCA); and 3) Stretched Lens Array SquareRigger (SLASR). The purpose of the Thin Film UltraFlex (TFUF) Program is to mature and validate the use of advanced flexible thin film photovoltaics blankets as the electrical subsystem element within an UltraFlex solar array structural system. In this program operational prototype flexible array segments, using United Solar amorphous silicon cells, are being manufactured and tested for the flight qualified UltraFlex structure. In addition, large size (e.g. 10 kW GEO) TFUF wing systems are being designed and analyzed. Thermal cycle and electrical test and analysis results from the TFUF program are presented. The purpose of the second program entitled, Low Cost/Mass Electrostatically Clean Solar Array (ESCA) System, is to develop an Electrostatically Clean Solar Array meeting NASA s design requirements and ready this technology for commercialization and use on the NASA MMS and GED missions. The ESCA designs developed use flight proven materials and processes to create a ESCA system that yields low cost, low mass, high reliability, high power density, and is adaptable to any cell type and coverglass thickness. All program objectives, which included developing specifications, creating ESCA concepts, concept analysis and trade studies, producing detailed designs of the most promising ESCA treatments, manufacturing ESCA demonstration panels, and LEO (2,000 cycles) and GEO (1,350 cycles) thermal cycling testing of the down-selected designs were successfully achieved. The purpose of the third program entitled, "High Power Platform for the Stretched Lens Array," is to develop an extremely lightweight, high efficiency, high power, high voltage, and low stowed volume solar array suitable for very high power (multi-kW to MW

  2. Drill/borescope System for the Mars Polar Pathfinder

    NASA Technical Reports Server (NTRS)

    Paige, D. A.; Wood, S. E.; Vasavada, A. R.

    1993-01-01

    The primary goals of the Mars Polar Pathfinder (MPP) Discovery Mission are to characterize the composition and structure of Mars' north polar ice cap, and to determine whether a climate record may be preserved in layers of ice and dust. The MPP would land as close as possible to the geographic north pole of Mars and use a set of instruments similar to those used by glaciologists to study polar ice caps on Earth: a radar sounder, a drill/borescope system, and a thermal probe. The drill/borescope system will drill approximately 50 cm into the surface and image the sides of the hole at 10 micron resolution for compositional and stratigraphic analysis. Several uncertainties have guided the development of this instrument, and they are discussed.

  3. Mars Pathfinder Near-Field Rock Distribution Re-Evaluation

    NASA Technical Reports Server (NTRS)

    Haldemann, A. F. C.; Golombek, M. P.

    2003-01-01

    We have completed analysis of a new near-field rock count at the Mars Pathfinder landing site and determined that the previously published rock count suggesting 16% cumulative fractional area (CFA) covered by rocks is incorrect. The earlier value is not so much wrong (our new CFA is 20%), as right for the wrong reason: both the old and the new CFA's are consistent with remote sensing data, however the earlier determination incorrectly calculated rock coverage using apparent width rather than average diameter. Here we present details of the new rock database and the new statistics, as well as the importance of using rock average diameter for rock population statistics. The changes to the near-field data do not affect the far-field rock statistics.

  4. An Analysis of Coupling between the x1 and x12 Interferometers for LISA Pathfinder

    NASA Astrophysics Data System (ADS)

    Howard, Brittany

    2017-01-01

    Due to tolerances in the manufacturing process, noise from the jittering of the spacecraft housing LISA Pathfinder (LPF) is appearing in the differential measurement between its two test masses (TM's). This phenomenon manifests as a small but measurable coupling between the readouts of LPF's two heterodyne interferometers, x1 and x12. In this study, two LISA Pathfinder experiments are analyzed using three methods in an effort to characterize and quantify the coupling as well as to potentially identify its source. The main question considered is this: does the coupling change with the absolute displacement between the TM's? As a result of this work, reliable values for coupling between LPF's x1 and x12 interferometers are found, and they are seen to depend on the absolute displacement between the test masses to some degree. Completed at the Albert Einstein Institute for Gravitational Physics under the International REU program from the University of Florida.

  5. Baseline-dependent averaging in radio interferometry

    NASA Astrophysics Data System (ADS)

    Wijnholds, S. J.; Willis, A. G.; Salvini, S.

    2018-05-01

    This paper presents a detailed analysis of the applicability and benefits of baseline-dependent averaging (BDA) in modern radio interferometers and in particular the Square Kilometre Array. We demonstrate that BDA does not affect the information content of the data other than a well-defined decorrelation loss for which closed form expressions are readily available. We verify these theoretical findings using simulations. We therefore conclude that BDA can be used reliably in modern radio interferometry allowing a reduction of visibility data volume (and hence processing costs for handling visibility data) by more than 80 per cent.

  6. The Fuge Tube Diode Array Spectrophotometer

    ERIC Educational Resources Information Center

    Arneson, B. T.; Long, S. R.; Stewart, K. K.; Lagowski, J. J.

    2008-01-01

    We present the details for adapting a diode array UV-vis spectrophotometer to incorporate the use of polypropylene microcentrifuge tubes--fuge tubes--as cuvettes. Optical data are presented validating that the polyethylene fuge tubes are equivalent to the standard square cross section polystyrene or glass cuvettes generally used in…

  7. Charge-Induced Force Noise on Free-Falling Test Masses: Results from LISA Pathfinder.

    PubMed

    Armano, M; Audley, H; Auger, G; Baird, J T; Binetruy, P; Born, M; Bortoluzzi, D; Brandt, N; Bursi, A; Caleno, M; Cavalleri, A; Cesarini, A; Cruise, M; Danzmann, K; de Deus Silva, M; Diepholz, I; Dolesi, R; Dunbar, N; Ferraioli, L; Ferroni, V; Fitzsimons, E D; Flatscher, R; Freschi, M; Gallegos, J; García Marirrodriga, C; Gerndt, R; Gesa, L; Gibert, F; Giardini, D; Giusteri, R; Grimani, C; Grzymisch, J; Harrison, I; Heinzel, G; Hewitson, M; Hollington, D; Hueller, M; Huesler, J; Inchauspé, H; Jennrich, O; Jetzer, P; Johlander, B; Karnesis, N; Kaune, B; Killow, C J; Korsakova, N; Lloro, I; Liu, L; López-Zaragoza, J P; Maarschalkerweerd, R; Madden, S; Mance, D; Martín, V; Martin-Polo, L; Martino, J; Martin-Porqueras, F; Mateos, I; McNamara, P W; Mendes, J; Mendes, L; Moroni, A; Nofrarias, M; Paczkowski, S; Perreur-Lloyd, M; Petiteau, A; Pivato, P; Plagnol, E; Prat, P; Ragnit, U; Ramos-Castro, J; Reiche, J; Romera Perez, J A; Robertson, D I; Rozemeijer, H; Rivas, F; Russano, G; Sarra, P; Schleicher, A; Slutsky, J; Sopuerta, C; Sumner, T J; Texier, D; Thorpe, J I; Trenkel, C; Vetrugno, D; Vitale, S; Wanner, G; Ward, H; Wass, P J; Wealthy, D; Weber, W J; Wittchen, A; Zanoni, C; Ziegler, T; Zweifel, P

    2017-04-28

    We report on electrostatic measurements made on board the European Space Agency mission LISA Pathfinder. Detailed measurements of the charge-induced electrostatic forces exerted on free-falling test masses (TMs) inside the capacitive gravitational reference sensor are the first made in a relevant environment for a space-based gravitational wave detector. Employing a combination of charge control and electric-field compensation, we show that the level of charge-induced acceleration noise on a single TM can be maintained at a level close to 1.0  fm s^{-2} Hz^{-1/2} across the 0.1-100 mHz frequency band that is crucial to an observatory such as the Laser Interferometer Space Antenna (LISA). Using dedicated measurements that detect these effects in the differential acceleration between the two test masses, we resolve the stochastic nature of the TM charge buildup due to interplanetary cosmic rays and the TM charge-to-force coupling through stray electric fields in the sensor. All our measurements are in good agreement with predictions based on a relatively simple electrostatic model of the LISA Pathfinder instrument.

  8. adrift, a novel bnl-induced Drosophila gene, required for tracheal pathfinding into the CNS.

    PubMed

    Englund, C; Uv, A E; Cantera, R; Mathies, L D; Krasnow, M A; Samakovlis, C

    1999-04-01

    Neurons and glial cells provide guidance cues for migrating neurons. We show here that migrating epithelial cells also contact specific neurons and glia during their pathfinding, and we describe the first gene required in the process. In wild-type Drosophila embryos, the ganglionic tracheal branch navigates a remarkably complex path along specific neural and glial substrata, switching substrata five times before reaching its ultimate target in the CNS. In adrift mutants, ganglionic branches migrate normally along the intersegmental nerve, but sporadically fail to switch to the segmental nerve and enter the CNS; they wind up meandering along the ventral epidermis instead. adrift encodes a novel nuclear protein with an evolutionarily conserved motif. The gene is required in the trachea and is expressed in the leading cells of migrating ganglionic branches where it is induced by the branchless FGF pathway. We propose that Adrift regulates expression of tracheal genes required for pathfinding on the segmental nerve, and FGF induction of adrift expression in migrating tracheal cells promotes the switch from the intersegmental to the segmental nerve.

  9. The Australian Geodetic Observing Program. Current Status and Future Plans

    NASA Astrophysics Data System (ADS)

    Johnston, G.; Dawson, J. H.

    2015-12-01

    Over the last decade, the Australian government has through programs like AuScope, the Asia Pacific Reference Frame (APREF), and the Pacific Sea Level Monitoring (PSLM) Project made a significant contribution to the Global Geodetic Observing Program. In addition to supporting the national research priorities, this contribution is justified by Australia's growing economic dependence on precise positioning to underpin efficient transportation, geospatial data management, and industrial automation (e.g., robotic mining and precision agriculture) and the consequent need for the government to guarantee provision of precise positioning products to the Australian community. It is also well recognised within Australia that there is an opportunity to exploit our near unique position as being one of the few regions in the world to see all new and emerging satellite navigation systems including Galileo (Europe), GPS III (USA), GLONASS (Russia), Beidou (China), QZSS (Japan) and IRNSS (India). It is in this context that the Australian geodetic program will build on earlier efforts and further develop its key geodetic capabilities. This will include the creation of an independent GNSS analysis capability that will enable Australia to contribute to the International GNSS Service (IGS) and an upgrade of key geodetic infrastructure including the national VLBI and GNSS arrays. This presentation will overview the significant geodetic activities undertaken by the Australian government and highlight its future plans.

  10. Characterization of the Martian surface deposits by the Mars Pathfinder rover, Sojourner.

    NASA Astrophysics Data System (ADS)

    Matijevic, J. R.; Crisp, J.; Bickler, D. B.; Banes, R. S.; Cooper, B. K.; Eisen, H. J.; Gensler, J.; Haldemann, A.; Hartman, F.; Jewett, K. A.; Matthies, L. H.; Laubach, S. L.; Mishkin, A. H.; Morrison, J. C.; Nguyen, T. T.; Sirota, A. R.; Stone, H. W.; Stride, S.; Sword, L. F.; Tarsala, J. A.; Thompson, A. D.; Wallace, M. T.; Welch, R.; Wellman, E.; Wilcox, B. H.; Ferguson, D.; Jenkins, P.; Kolecki, J.; Landis, G. A.; Wilt, D.; Rover Team

    1997-12-01

    The Mars Pathfinder rover discovered pebbles on the surface and in rocks that may be sedimentary - not volcanic - in origin. Surface pebbles may have been rounded by Ares flood waters or liberated by weathering of sedimentary rocks called conglomerates. Conglomerates imply that water existed elsewhere and earlier than the Ares flood. Most soil-like deposits are similar to moderately dense soils on Earth. Small amounts of dust are currently settling from the atmosphere.

  11. Highlights from the Telescope Array Experiment

    NASA Astrophysics Data System (ADS)

    Sagawa, H.

    2014-10-01

    The Telescope Array (TA) is the largest experiment in the Northern Hemisphere currently studying the origin and nature of ultra-high-energy cosmic rays above ˜1018 eV by measuring their energy spectrum, mass composition, and arrival directions. It is located in the western desert of central Utah, USA. The TA detector consists of a surface array of 507 scintillation counters, deployed on a square grid of 1.2-km spacing that covers approximately 700 km2, and 38 fluorescence telescopes located at three sites looking over the surface array. The TA commenced hybrid observation with both sets of detectors in 2008. Here, we present recent results from these 5 years of data and outline our ongoing and near future plans.

  12. Exact least squares adaptive beamforming using an orthogonalization network

    NASA Astrophysics Data System (ADS)

    Yuen, Stanley M.

    1991-03-01

    The pros and cons of various classical and state-of-the-art methods in adaptive array processing are discussed, and the relevant concepts and historical developments are pointed out. A set of easy-to-understand equations for facilitating derivation of any least-squares-based algorithm is derived. Using this set of equations and incorporating all of the useful properties associated with various techniques, an efficient solution to the real-time adaptive beamforming problem is developed.

  13. Calibration of LOFAR data on the cloud

    NASA Astrophysics Data System (ADS)

    Sabater, J.; Sánchez-Expósito, S.; Best, P.; Garrido, J.; Verdes-Montenegro, L.; Lezzi, D.

    2017-04-01

    New scientific instruments are starting to generate an unprecedented amount of data. The Low Frequency Array (LOFAR), one of the Square Kilometre Array (SKA) pathfinders, is already producing data on a petabyte scale. The calibration of these data presents a huge challenge for final users: (a) extensive storage and computing resources are required; (b) the installation and maintenance of the software required for the processing is not trivial; and (c) the requirements of calibration pipelines, which are experimental and under development, are quickly evolving. After encountering some limitations in classical infrastructures like dedicated clusters, we investigated the viability of cloud infrastructures as a solution. We found that the installation and operation of LOFAR data calibration pipelines is not only possible, but can also be efficient in cloud infrastructures. The main advantages were: (1) the ease of software installation and maintenance, and the availability of standard APIs and tools, widely used in the industry; this reduces the requirement for significant manual intervention, which can have a highly negative impact in some infrastructures; (2) the flexibility to adapt the infrastructure to the needs of the problem, especially as those demands change over time; (3) the on-demand consumption of (shared) resources. We found that a critical factor (also in other infrastructures) is the availability of scratch storage areas of an appropriate size. We found no significant impediments associated with the speed of data transfer, the use of virtualization, the use of external block storage, or the memory available (provided a minimum threshold is reached). Finally, we considered the cost-effectiveness of a commercial cloud like Amazon Web Services. While a cloud solution is more expensive than the operation of a large, fully-utilized cluster completely dedicated to LOFAR data reduction, we found that its costs are competitive if the number of datasets to be

  14. Optimum SNR data compression in hardware using an Eigencoil array.

    PubMed

    King, Scott B; Varosi, Steve M; Duensing, G Randy

    2010-05-01

    With the number of receivers available on clinical MRI systems now ranging from 8 to 32 channels, data compression methods are being explored to lessen the demands on the computer for data handling and processing. Although software-based methods of compression after reception lessen computational requirements, a hardware-based method before the receiver also reduces the number of receive channels required. An eight-channel Eigencoil array is constructed by placing a hardware radiofrequency signal combiner inline after preamplification, before the receiver system. The Eigencoil array produces signal-to-noise ratio (SNR) of an optimal reconstruction using a standard sum-of-squares reconstruction, with peripheral SNR gains of 30% over the standard array. The concept of "receiver channel reduction" or MRI data compression is demonstrated, with optimal SNR using only four channels, and with a three-channel Eigencoil, superior sum-of-squares SNR was achieved over the standard eight-channel array. A three-channel Eigencoil portion of a product neurovascular array confirms in vivo SNR performance and demonstrates parallel MRI up to R = 3. This SNR-preserving data compression method advantageously allows users of MRI systems with fewer receiver channels to achieve the SNR of higher-channel MRI systems. (c) 2010 Wiley-Liss, Inc.

  15. Model Checking JAVA Programs Using Java Pathfinder

    NASA Technical Reports Server (NTRS)

    Havelund, Klaus; Pressburger, Thomas

    2000-01-01

    This paper describes a translator called JAVA PATHFINDER from JAVA to PROMELA, the "programming language" of the SPIN model checker. The purpose is to establish a framework for verification and debugging of JAVA programs based on model checking. This work should be seen in a broader attempt to make formal methods applicable "in the loop" of programming within NASA's areas such as space, aviation, and robotics. Our main goal is to create automated formal methods such that programmers themselves can apply these in their daily work (in the loop) without the need for specialists to manually reformulate a program into a different notation in order to analyze the program. This work is a continuation of an effort to formally verify, using SPIN, a multi-threaded operating system programmed in Lisp for the Deep-Space 1 spacecraft, and of previous work in applying existing model checkers and theorem provers to real applications.

  16. LISA pathfinder appreciably constrains collapse models

    NASA Astrophysics Data System (ADS)

    Helou, Bassam; Slagmolen, B. J. J.; McClelland, David E.; Chen, Yanbei

    2017-04-01

    Spontaneous collapse models are phenomological theories formulated to address major difficulties in macroscopic quantum mechanics. We place significant bounds on the parameters of the leading collapse models, the continuous spontaneous localization (CSL) model, and the Diosi-Penrose (DP) model, by using LISA Pathfinder's measurement, at a record accuracy, of the relative acceleration noise between two free-falling macroscopic test masses. In particular, we bound the CSL collapse rate to be at most (2.96 ±0.12 ) ×10-8 s-1 . This competitive bound explores a new frequency regime, 0.7 to 20 mHz, and overlaps with the lower bound 10-8 ±2 s-1 proposed by Adler in order for the CSL collapse noise to be substantial enough to explain the phenomenology of quantum measurement. Moreover, we bound the regularization cutoff scale used in the DP model to prevent divergences to be at least 40.1 ±0.5 fm , which is larger than the size of any nucleus. Thus, we rule out the DP model if the cutoff is the size of a fundamental particle.

  17. Statistical analysis of soil geochemical data to identify pathfinders associated with mineral deposits: An example from the Coles Hill uranium deposit, Virginia, USA

    USGS Publications Warehouse

    Levitan, Denise M.; Zipper, Carl E.; Donovan, Patricia; Schreiber, Madeline E.; Seal, Robert; Engle, Mark A.; Chermak, John A.; Bodnar, Robert J.; Johnson, Daniel K.; Aylor, Joseph G.

    2015-01-01

    Soil geochemical anomalies can be used to identify pathfinders in exploration for ore deposits. In this study, compositional data analysis is used with multivariate statistical methods to analyse soil geochemical data collected from the Coles Hill uranium deposit, Virginia, USA, to identify pathfinders associated with this deposit. Elemental compositions and relationships were compared between the collected Coles Hill soil and reference soil samples extracted from a regional subset of a national-scale geochemical survey. Results show that pathfinders for the Coles Hill deposit include light rare earth elements (La and Ce), which, when normalised by their Al content, are correlated with U/Al, and elevated Th/Al values, which are not correlated with U/Al, supporting decoupling of U from Th during soil generation. These results can be used in genetic and weathering models of the Coles Hill deposit, and can also be applied to future prospecting for similar U deposits in the eastern United States, and in regions with similar geological/climatic conditions.

  18. Cerberus Plains: A most excellent Pathfinder landing site

    NASA Technical Reports Server (NTRS)

    Plescia, Jeff B.

    1994-01-01

    The Cerberus Plains in southeastern Elysium and western Amazonis cover greater than 10(exp 5) sq km, extending an east-west distance of approximately 3000 km and a north-south distance of up to 700 km near 195 deg. Crater numbers are 89 plus or minus 15 craters greater than 1 km/10(exp 6) sq km, indicating a stratigraphic age of Upper Amazonian and an absolute age of 200-500 Ma. The material forming the surface is referred to as the Cerberus Formation. The two ideas postulated about the unit's origin are fluvial and volcanic. Regardless of which interpretation is correct, the Cerberus Plains is an important candidate for a pathfinder landing site because it represents the youngest major geologic event (be it fluvial or volcanic) on Mars.

  19. Correlations between solar wind parameters and auroral kilometric radiation intensity

    NASA Technical Reports Server (NTRS)

    Gallagher, D. L.; Dangelo, N.

    1981-01-01

    The relationship between solar wind properties and the influx of energy into the nightside auroral region as indicated by the intensity of auroral kilometric radiation is investigated. Smoothed Hawkeye satellite observations of auroral radiation at 178, 100 and 56.2 kHz for days 160 through 365 of 1974 are compared with solar wind data from the composite Solar Wind Plasma Data Set, most of which was supplied by the IMP-8 spacecraft. Correlations are made between smoothed daily averages of solar wind ion density, bulk flow speed, total IMF strength, electric field, solar wind speed in the southward direction, solar wind speed multiplied by total IMF strength, the substorm parameter epsilon and the Kp index. The greatest correlation is found between solar wind bulk flow speed and auroral radiation intensity, with a linear correlation coefficient of 0.78 for the 203 daily averages examined. A possible mechanism for the relationship may be related to the propagation into the nightside magnetosphere of low-frequency long-wavelength electrostatic waves produced in the magnetosheath by the solar wind.

  20. Reconsidering the advantages of the three-dimensional representation of the interferometric transform for imaging with non-coplanar baselines and wide fields of view

    NASA Astrophysics Data System (ADS)

    Smith, D. M. P.; Young, A.; Davidson, D. B.

    2017-07-01

    Radio telescopes with baselines that span thousands of kilometres and with fields of view that span tens of degrees have been recently deployed, such as the Low Frequency Array, and are currently being developed, such as the Square Kilometre Array. Additionally, there are proposals for space-based instruments with all-sky imaging capabilities, such as the Orbiting Low Frequency Array. Such telescopes produce observations with three-dimensional visibility distributions and curved image domains. In most work to date, the visibility distribution has been converted to a planar form to compute the brightness map using a two-dimensional Fourier transform. The celestial sphere is faceted in order to counter pixel distortion at wide angles, with each such facet requiring a unique planar form of the visibility distribution. Under the above conditions, the computational and storage complexities of this approach can become excessive. On the other hand, when using the direct Fourier transform approach, which maintains the three-dimensional shapes of the visibility distribution and celestial sphere, the non-coplanar visibility component requires no special attention. Furthermore, as the celestial samples are placed directly on the curved surface of the celestial sphere, pixel distortion at wide angles is avoided. In this paper, a number of examples illustrate that under these conditions (very long baselines and very wide fields of view) the costs of the direct Fourier transform may be comparable to (or even lower than) methods that utilise the two-dimensional fast Fourier transform.

  1. Big Crater as Viewed by Pathfinder Lander - Anaglyph

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The 'Big Crater' is actually a relatively small Martian crater to the southeast of the Mars Pathfinder landing site. It is 1500 meters (4900 feet) in diameter, or about the same size as Meteor Crater in Arizona. Superimposed on the rim of Big Crater (the central part of the rim as seen here) is a smaller crater nicknamed 'Rimshot Crater.' The distance to this smaller crater, and the nearest portion of the rim of Big Crater, is 2200 meters (7200 feet). To the right of Big Crater, south from the spacecraft, almost lost in the atmospheric dust 'haze,' is the large streamlined mountain nicknamed 'Far Knob.' This mountain is over 450 meters (1480 feet) tall, and is over 30 kilometers (19 miles) from the spacecraft. Another, smaller and closer knob, nicknamed 'Southeast Knob' can be seen as a triangular peak to the left of the flanks of the Big Crater rim. This knob is 21 kilometers (13 miles) southeast from the spacecraft.

    The larger features visible in this scene - Big Crater, Far Knob, and Southeast Knob - were discovered on the first panoramas taken by the IMP camera on the 4th of July, 1997, and subsequently identified in Viking Orbiter images taken over 20 years ago. The scene includes rocky ridges and swales or 'hummocks' of flood debris that range from a few tens of meters away from the lander to the distance of South Twin Peak. The largest rock in the nearfield, just left of center in the foreground, nicknamed 'Otter', is about 1.5 meters (4.9 feet) long and 10 meters (33 feet) from the spacecraft.

    This view of Big Crater was produced by combining 6 individual 'Superpan' scenes from the left and right eyes of the IMP camera. Each frame consists of 8 individual frames (left eye) and 7 frames (right eye) taken with different color filters that were enlarged by 500% and then co-added using Adobe Photoshop to produce, in effect, a super-resolution panchromatic frame that is sharper than an individual frame would be.

    The anaglyph view of Big Crater was

  2. The fabrication of ordered arrays of exchange biased Ni/FeF2 nanostructures.

    PubMed

    Kovylina, M; Erekhinsky, M; Morales, R; Schuller, I K; Labarta, A; Batlle, X

    2010-04-30

    The fabrication of ordered arrays of exchange biased Ni/FeF(2) nanostructures by focused ion beam lithography is reported. High quality nano-elements, with controlled removal depth and no significant re-deposition, were carved using small ion beam currents (30 pA), moderate dwell times (1 micros) and repeated passages over the same area. Two types of nanostructures were fabricated: square arrays of circular dots with diameters from 125 +/- 8 to 500 +/- 12 nm and periodicities ranging from 200 +/- 8 to 1000 +/- 12 nm, and square arrays of square antidots (207 +/- 8 nm in edge length) with periodicities ranging from 300 +/- 8 to 1200 +/- 12 nm. The arrays were characterized using scanning ion and electron microscopy, and atomic force microscopy. The effect of the patterning on the exchange bias field (i.e., the shift in the hysteresis loop of ferromagnetic Ni due to proximity to antiferromagnetic FeF(2)) was studied using magneto-transport measurements. These high quality nanostructures offer a unique method to address some of the open questions regarding the microscopic origin of exchange bias. This is not only of major relevance in the fabrication and miniaturization of magnetic devices but it is also one of the important proximity phenomena in nanoscience and materials science.

  3. Coexpression of high-voltage-activated ion channels Kv3.4 and Cav1.2 in pioneer axons during pathfinding in the developing rat forebrain.

    PubMed

    Huang, Chia-Yi; Chu, Dachen; Hwang, Wei-Chao; Tsaur, Meei-Ling

    2012-11-01

    Precise axon pathfinding is crucial for establishment of the initial neuronal network during development. Pioneer axons navigate without the help of preexisting axons and pave the way for follower axons that project later. Voltage-gated ion channels make up the intrinsic electrical activity of pioneer axons and regulate axon pathfinding. To elucidate which channel molecules are present in pioneer axons, immunohistochemical analysis was performed to examine 14 voltage-gated ion channels (Kv1.1-Kv1.3, Kv3.1-Kv3.4, Kv4.3, Cav1.2, Cav1.3, Cav2.2, Nav1.2, Nav1.6, and Nav1.9) in nine axonal tracts in the developing rat forebrain, including the optic nerve, corpus callosum, corticofugal fibers, thalamocortical axons, lateral olfactory tract, hippocamposeptal projection, anterior commissure, hippocampal commissure, and medial longitudinal fasciculus. We found A-type K⁺ channel Kv3.4 in both pioneer axons and early follower axons and L-type Ca²⁺ channel Cav1.2 in pioneer axons and early and late follower axons. Spatially, Kv3.4 and Cav1.2 were colocalized with markers of pioneer neurons and pioneer axons, such as deleted in colorectal cancer (DCC), in most fiber tracts examined. Temporally, Kv3.4 and Cav1.2 were expressed abundantly in most fiber tracts during axon pathfinding but were downregulated beginning in synaptogenesis. By contrast, delayed rectifier Kv channels (e.g., Kv1.1) and Nav channels (e.g., Nav1.2) were absent from these fiber tracts (except for the corpus callosum) during pathfinding of pioneer axons. These data suggest that Kv3.4 and Cav1.2, two high-voltage-activated ion channels, may act together to control Ca²⁺ -dependent electrical activity of pioneer axons and play important roles during axon pathfinding. Copyright © 2012 Wiley Periodicals, Inc.

  4. The EUSO-Balloon pathfinder

    NASA Astrophysics Data System (ADS)

    Adams, J. H.; Ahmad, S.; Albert, J.-N.; Allard, D.; Anchordoqui, L.; Andreev, V.; Anzalone, A.; Arai, Y.; Asano, K.; Ave Pernas, M.; Baragatti, P.; Barrillon, P.; Batsch, T.; Bayer, J.; Bechini, R.; Belenguer, T.; Bellotti, R.; Belov, K.; Berlind, A. A.; Bertaina, M.; Biermann, P. L.; Biktemerova, S.; Blaksley, C.; Blanc, N.; Błȩcki, J.; Blin-Bondil, S.; Blümer, J.; Bobik, P.; Bogomilov, M.; Bonamente, M.; Briggs, M. S.; Briz, S.; Bruno, A.; Cafagna, F.; Campana, D.; Capdevielle, J.-N.; Caruso, R.; Casolino, M.; Cassardo, C.; Castellinic, G.; Catalano, C.; Catalano, G.; Cellino, A.; Chikawa, M.; Christl, M. J.; Cline, D.; Connaughton, V.; Conti, L.; Cordero, G.; Crawford, H. J.; Cremonini, R.; Csorna, S.; Dagoret-Campagne, S.; de Castro, A. J.; De Donato, C.; de la Taille, C.; De Santis, C.; del Peral, L.; Dell'Oro, A.; De Simone, N.; Di Martino, M.; Distratis, G.; Dulucq, F.; Dupieux, M.; Ebersoldt, A.; Ebisuzaki, T.; Engel, R.; Falk, S.; Fang, K.; Fenu, F.; Fernández-Gómez, I.; Ferrarese, S.; Finco, D.; Flamini, M.; Fornaro, C.; Franceschi, A.; Fujimoto, J.; Fukushima, M.; Galeotti, P.; Garipov, G.; Geary, J.; Gelmini, G.; Giraudo, G.; Gonchar, M.; González Alvarado, C.; Gorodetzky, P.; Guarino, F.; Guzmán, A.; Hachisu, Y.; Harlov, B.; Haungs, A.; Hernández Carretero, J.; Higashide, K.; Ikeda, D.; Ikeda, H.; Inoue, N.; Inoue, S.; Insolia, A.; Isgrò, F.; Itow, Y.; Joven, E.; Judd, E. G.; Jung, A.; Kajino, F.; Kajino, T.; Kaneko, I.; Karadzhov, Y.; Karczmarczyk, J.; Karus, M.; Katahira, K.; Kawai, K.; Kawasaki, Y.; Keilhauer, B.; Khrenov, B. A.; Kim, J.-S.; Kim, S.-W.; Kim, S.-W.; Kleifges, M.; Klimov, P. A.; Kolev, D.; Kreykenbohm, I.; Kudela, K.; Kurihara, Y.; Kusenko, A.; Kuznetsov, E.; Lacombe, M.; Lachaud, C.; Lee, J.; Licandro, J.; Lim, H.; López, F.; Maccarone, M. C.; Mannheim, K.; Maravilla, D.; Marcelli, L.; Marini, A.; Martinez, O.; Masciantonio, G.; Mase, K.; Matev, R.; Medina-Tanco, G.; Mernik, T.; Miyamoto, H.; Miyazaki, Y.; Mizumoto, Y.; Modestino, G.; Monaco, A.; Monnier-Ragaigne, D.; Morales de los Ríos, J. A.; Moretto, C.; Morozenko, V. S.; Mot, B.; Murakami, T.; Murakami, M. Nagano; Nagata, M.; Nagataki, S.; Nakamura, T.; Napolitano, T.; Naumov, D.; Nava, R.; Neronov, A.; Nomoto, K.; Nonaka, T.; Ogawa, T.; Ogio, S.; Ohmori, H.; Olinto, A. V.; Orleański, P.; Osteria, G.; Panasyuk, M. I.; Parizot, E.; Park, I. H.; Park, H. W.; Pastircak, B.; Patzak, T.; Paul, T.; Pennypacker, C.; Perez Cano, S.; Peter, T.; Picozza, P.; Pierog, T.; Piotrowski, L. W.; Piraino, S.; Plebaniak, Z.; Pollini, A.; Prat, P.; Prévôt, G.; Prieto, H.; Putis, M.; Reardon, P.; Reyes, M.; Ricci, M.; Rodríguez, I.; Rodríguez Frías, M. D.; Ronga, F.; Roth, M.; Rothkaehl, H.; Roudil, G.; Rusinov, I.; Rybczyński, M.; Sabau, M. D.; Sáez-Cano, G.; Sagawa, H.; Saito, A.; Sakaki, N.; Sakata, M.; Salazar, H.; Sánchez, S.; Santangelo, A.; Santiago Crúz, L.; Sanz Palomino, M.; Saprykin, O.; Sarazin, F.; Sato, H.; Sato, M.; Schanz, T.; Schieler, H.; Scotti, V.; Segreto, A.; Selmane, S.; Semikoz, D.; Serra, M.; Sharakin, S.; Shibata, T.; Shimizu, H. M.; Shinozaki, K.; Shirahama, T.; Siemieniec-Oziȩbło, G.; Silva López, H. H.; Sledd, J.; Słomińska, K.; Sobey, A.; Sugiyama, T.; Supanitsky, D.; Suzuki, M.; Szabelska, B.; Szabelski, J.; Tajima, F.; Tajima, N.; Tajima, T.; Takahashi, Y.; Takami, H.; Takeda, M.; Takizawa, Y.; Tenzer, C.; Tibolla, O.; Tkachev, L.; Tokuno, H.; Tomida, T.; Tone, N.; Toscano, S.; Trillaud, F.; Tsenov, R.; Tsunesada, Y.; Tsuno, K.; Tymieniecka, T.; Uchihori, Y.; Unger, M.; Vaduvescu, O.; Valdés-Galicia, J. F.; Vallania, P.; Valore, L.; Vankova, G.; Vigorito, C.; Villaseñor, L.; von Ballmoos, P.; Wada, S.; Watanabe, J.; Watanabe, S.; Watts, J.; Weber, M.; Weiler, T. J.; Wibig, T.; Wiencke, L.; Wille, M.; Wilms, J.; Włodarczyk, Z.; Yamamoto, T.; Yamamoto, Y.; Yang, J.; Yano, H.; Yashin, I. V.; Yonetoku, D.; Yoshida, K.; Yoshida, S.; Young, R.; Zotov, M. Yu.; Zuccaro Marchi, A.

    2015-11-01

    EUSO-Balloon is a pathfinder for JEM-EUSO, the Extreme Universe Space Observatory which is to be hosted on-board the International Space Station. As JEM-EUSO is designed to observe Ultra-High Energy Cosmic Rays (UHECR)-induced Extensive Air Showers (EAS) by detecting their ultraviolet light tracks "from above", EUSO-Balloon is a nadir-pointing UV telescope too. With its Fresnel Optics and Photo-Detector Module, the instrument monitors a 50 km2 ground surface area in a wavelength band of 290-430 nm, collecting series of images at a rate of 400,000 frames/sec. The objectives of the balloon demonstrator are threefold: a) perform a full end-to-end test of a JEM-EUSO prototype consisting of all the main subsystems of the space experiment, b) measure the effective terrestrial UV background, with a spatial and temporal resolution relevant for JEM-EUSO. c) detect tracks of ultraviolet light from near space for the first time. The latter is a milestone in the development of UHECR science, paving the way for any future space-based UHECR observatory. On August 25, 2014, EUSO-Balloon was launched from Timmins Stratospheric Balloon Base (Ontario, Canada) by the balloon division of the French Space Agency CNES. From a float altitude of 38 km, the instrument operated during the entire astronomical night, observing UV-light from a variety of ground-covers and from hundreds of simulated EASs, produced by flashers and a laser during a two-hour helicopter under-flight.

  5. Cometary kilometric radio waves and plasma waves correlated with ion pick-up effect at Comet Halley

    NASA Technical Reports Server (NTRS)

    Oya, H.; Morioka, A.; Miyake, W.; Smith, E. J.; Tsurutani, B. T.

    1985-01-01

    Bow-shock movements at Comet Halley are inferred from the discrete spectra of the cometary kilometric radiation (30-195 kHz); the observed emissions can be interpreted as being generated and propagating from the moving shock. The shock motion is possibly associated with the time variation of the solar wind and cometary outgassing. It is concluded that these plasma wave phenomena are manifestations of ion pick-up processes, which occur even in a remote region 7 million to 10 million km from the cometary nucleus.

  6. Longwave Radiative Flux Calculations in the TOVS Pathfinder Path A Data Set

    NASA Technical Reports Server (NTRS)

    Mehta, Amita; Susskind, Joel

    1999-01-01

    A radiative transfer model developed to calculate outgoing longwave radiation (OLR) and downwelling longwave, surface flux (DSF) from the Television and Infrared Operational Satellite (TIROS) Operational Vertical Sounder (TOVS) Pathfinder Path A retrieval products is described. The model covers the spectral range of 2 to 2800 cm in 14 medium medium spectral bands. For each band, transmittances are parameterized as a function of temperature, water vapor, and ozone profiles. The form of the band transmittance parameterization is a modified version of the approach we use to model channel transmittances for the High Resolution Infrared Sounder 2 (HIRS2) instrument. We separately derive effective zenith angle for each spectral band such that band-averaged radiance calculated at that angle best approximates directionally integrated radiance for that band. We develop the transmittance parameterization at these band-dependent effective zenith angles to incorporate directional integration of radiances required in the calculations of OLR and DSF. The model calculations of OLR and DSF are accurate and differ by less than 1% from our line-by-line calculations. Also, the model results are within 1% range of other line-by-line calculations provided by the Intercomparison of Radiation Codes in Climate Models (ICRCCM) project for clear-sky and cloudy conditions. The model is currently used to calculate global, multiyear (1985-1998) OLR and DSF from the TOVS Pathfinder Path A Retrievals.

  7. Transparent, Conductive Coatings Developed for Arc-Proof Solar Arrays

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Transparent, conductive thin-film coatings have many potential applications where a surface must be able to dissipate electrical charges without sacrificing its optical properties. Such applications include automotive and aircraft windows, heat mirrors, optoelectronic devices, gas sensors, and solar cell array surfaces for space applications. Many spacecraft missions require that solar cell array surfaces dissipate charges in order to avoid damage such as electronic upsets, formation of pinholes in the protective coatings on solar array blankets, and contamination due to deposition of sputtered products. In tests at the NASA Lewis Research Center, mixed thin-films of sputter-deposited indium tin oxide (ITO) and magnesium fluoride (MgF2) that could be tailored to the desired sheet resistivity, showed transmittance values of greater than 90 percent. The samples evaluated were composed of mixed, thin-film ITO/MgF2 coatings, with a nominal thickness of 650 angstroms, deposited onto glass substrates. Preliminary results indicated that these coatings were durable to vacuum ultraviolet radiation and atomic oxygen. These coatings show promise for use on solar array surfaces in polar low-Earth-orbit environments, where a sheet resistivity of less than 10(exp 8)/square is required, and in geosynchronous orbit environments, where a resistivity of less than 10(exp 9)/square is required.

  8. Bubble Transport through Micropillar Arrays

    NASA Astrophysics Data System (ADS)

    Lee, Kenneth; Savas, Omer

    2012-11-01

    In current energy research, artificial photosynthetic devices are being designed to split water and harvest hydrogen gas using energy from the sun. In one such design, hydrogen gas bubbles evolve on the catalytic surfaces of arrayed micropillars. If these bubbles are not promptly removed from the surface, they can adversely affect gas evolution rates, water flow rates, sunlight capture, and heat management of the system. Therefore, an efficient method of collecting the evolved gas bubbles is crucial. Preliminary flow visualization has been conducted of bubbles advecting through dense arrays of pillars. Bubbles moving through square and hexagonal arrays are tracked, and the results are qualitatively described. Initial attempts to correlate bubble motion with relevant lengthscales and forces are also presented. These observations suggest how bubble transport within such pillar arrays can be managed, as well as guide subsequent experiments that investigate bubble evolution and collection. This material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993.

  9. Australian Brain Alliance.

    PubMed

    2016-11-02

    A proposal for an Australian Brain Initiative (ABI) is under development by members of the Australian Brain Alliance. Here we discuss the goals of the ABI, its areas of research focus, its context in the Australian research setting, and its necessity for ensuring continued success for Australian brain research. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. Mars Pathfinder Landing Site Workshop 2: Characteristics of the Ares Vallis Region and Field Trips in the Channeled Scabland, Washington

    NASA Technical Reports Server (NTRS)

    Golombek, M. P. (Editor); Edgett, K. S. (Editor); Rice, J. W., Jr. (Editor)

    1995-01-01

    This volume, the first of two comprising the technical report for this workshop, contains papers that have been accepted for presentation at the Mars Pathfinder Landing Site Workshop 2: Characteristics of the Ares Vallis Region, September 24-30, 1995, in Spokane, Washington. The Mars Pathfinder Project received a new start in October 1993 as one of the next missions in NASA's long-term Mars exploration program. The mission involves landing a single vehicle on the surface of Mars in 1997. The project is one of the first Discovery-class missions and is required to be a quick, low-cost mission and achieve a set of significant but focused engineering, science, and technology objectives. The primary objective is to demonstrate a low-cost cruise, entry, descent, and landing system required to place a payload on the martian surface in a safe, operational configuration. Additional objectives include the deployment and operation of various science instruments and a microrover. Pathfinder paves the way for a cost-effective implementation of future Mars lander missions. Also included in this volume is the field trip guide to the Channeled Scabland and Missoula Lake Break-out. On July 4, 1997, Mars Pathfinder is scheduled to land near 19.5 deg N, 32.8 deg W, in a portion of Ares Vallis. The landing ellipse covers a huge (100 x 200 km) area that appears to include both depositional and erosional landforms created by one or more giant, catastrophic floods. One of the best known terrestrial analogs to martian outflow channels (such as Ares Vallis) is the region known as the Channeled Scabland. The field trip guide describes some of the geomorphological features of the Channeled Scabland and adjacent Lake Missoula break-out area near Lake Pend Oreille, Idaho.

  11. Relationship Between Saturn Kilometric Radiation Emissions and Kronian Magnetotail Activity, as Compared with the Terrestrial Case

    NASA Astrophysics Data System (ADS)

    Jackman, C. M.; Lamy, L.; Freeman, M. P.; Cecconi, B.; Zarka, P.; Dougherty, M. K.; Kurth, W. S.

    2008-12-01

    Several examples of plasmoid passage associated with substorm-like reconnection in the magnetotail of Saturn have been discovered using data from the Cassini magnetometer [Jackman et al., 2008]. Some of these events (along with several others) have subsequently been found to be roughly associated with bursts of Saturn Kilometric Radiation (SKR) emission. We explore this link in detail, with particular emphasis on expansions of the radio emission to lower frequencies, signifying motion of the source along the field lines. We compare with observations of Auroral Kilometric Radiation (AKR) at Earth, which has been shown in some cases to have a separate low-frequency component associated with substorm onset [Morioka et al., 2007] We also wish to estimate the recurrence rate of kronian substorms. Previously for the case of the terrestrial magnetosphere, it has been found that the substorm phenomenon is identified with a component of the probability distribution of durations for which the AU or AL indices are above or below a fixed threshold, respectively [Freeman, Watkins and Riley, 2000]. After exploring the correlation between terrestrial substorms and AKR (which can be a reasonable proxy for the AE indices), we then apply the threshold crossing technique to Saturn by using data from the Cassini Radio and Plasma Wave Science (RPWS) instrument. We look at the probability distributions of Saturn's radio emissions in different frequency bands above and below fixed thresholds, with a view to revealing kronian substorms as a distinct separate population with a characteristic scale. References: Freeman, M.P., N.W. Watkins and D.J. Riley, (2000), Evidence for a solar wind origin of the power law burst lifetime distribution of the AE indices, Geophys. Res. Lett., 27, 8, 1087-1090. Jackman, C. M., C. S. Arridge, N. Krupp, E. J. Bunce, D. G. Mitchell, W. S. Kurth, H. J. McAndrews, M. K. Dougherty, C. T. Russell, N. Achilleos, A. J. Coates, and G. H. Jones (2008), A multi

  12. Pathfinder: The Geospatial Intelligence Magazine Serving the Front Line, March/April 2009. Volume 7, Number 2

    DTIC Science & Technology

    2009-04-01

    ADDRESS(ES) National Geospatial-Intelligence Agency,4600 Sangamore Rd Mail Stop D-54,Bethesda,MD, 20816 -5003 8. PERFORMING ORGANIZATION REPORT NUMBER 9...Bethesda, MD 20816 -5003 Telephone: (301) 227-7388, DSN 287-7388 E-mail: pathfinder@nga.mil Director Vice Adm. Robert B. Murrett, U.S. Navy Deputy

  13. Backshort-Under-Grid arrays for infrared astronomy

    NASA Astrophysics Data System (ADS)

    Allen, C. A.; Benford, D. J.; Chervenak, J. A.; Chuss, D. T.; Miller, T. M.; Moseley, S. H.; Staguhn, J. G.; Wollack, E. J.

    2006-04-01

    We are developing a kilopixel, filled bolometer array for space infrared astronomy. The array consists of three individual components, to be merged into a single, working unit; (1) a transition edge sensor bolometer array, operating in the milliKelvin regime, (2) a quarter-wave backshort grid, and (3) superconducting quantum interference device multiplexer readout. The detector array is designed as a filled, square grid of suspended, silicon bolometers with superconducting sensors. The backshort arrays are fabricated separately and will be positioned in the cavities created behind each detector during fabrication. The grids have a unique interlocking feature machined into the walls for positioning and mechanical stability. The spacing of the backshort beneath the detector grid can be set from ˜30 300 μm, by independently adjusting two process parameters during fabrication. The ultimate goal is to develop a large-format array architecture with background-limited sensitivity, suitable for a wide range of wavelengths and applications, to be directly bump bonded to a multiplexer circuit. We have produced prototype two-dimensional arrays having 8×8 detector elements. We present detector design, fabrication overview, and assembly technologies.

  14. Stretched Lens Array Squarerigger (SLASR) Technology Maturation

    NASA Technical Reports Server (NTRS)

    O'Neill, Mark; McDanal, A.J.; Howell, Joe; Lollar, Louis; Carrington, Connie; Hoppe, David; Piszczor, Michael; Suszuki, Nantel; Eskenazi, Michael; Aiken, Dan; hide

    2007-01-01

    Since April 2005, our team has been underway on a competitively awarded program sponsored by NASA s Exploration Systems Mission Directorate to develop, refine, and mature the unique solar array technology known as Stretched Lens Array SquareRigger (SLASR). SLASR offers an unprecedented portfolio of performance metrics, SLASR offers an unprecedented portfolio of performance metrics, including the following: Areal Power Density = 300 W/m2 (2005) - 400 W/m2 (2008 Target) Specific Power = 300 W/kg (2005) - 500 W/kg (2008 Target) for a Full 100 kW Solar Array Stowed Power = 80 kW/cu m (2005) - 120 kW/m3 (2008 Target) for a Full 100 kW Solar Array Scalable Array Capacity = 100 s of W s to 100 s of kW s Super-Insulated Small Cell Circuit = High-Voltage (300-600 V) Operation at Low Mass Penalty Super-Shielded Small Cell Circuit = Excellent Radiation Hardness at Low Mass Penalty 85% Cell Area Savings = 75% Lower Array Cost per Watt than One-Sun Array Modular, Scalable, & Mass-Producible at MW s per Year Using Existing Processes and Capacities

  15. Science with a lunar low-frequency array: From the dark ages of the Universe to nearby exoplanets

    NASA Astrophysics Data System (ADS)

    Jester, Sebastian; Falcke, Heino

    2009-05-01

    , thereby providing pristine cosmological information, e.g., on the inflationary phase of the universe. With a large array also exoplanet magnetospheres could be detected through Jupiter-like coherent bursts. Smaller arrays of order 102 antennas over ˜100 km, which could already be erected robotically by a single mission with current technology and launchers, could tackle surveys of steep-spectrum large-scale radio structures from galaxy clusters and radio galaxies. Also, at very low frequencies the structure of the interstellar medium can be studied tomographically. Moreover, radio emission from neutrino interactions within the moon can potentially be used to create a neutrino detector with a volume of several cubic kilometers. An ultra-high energy cosmic ray detector with thousands of square kilometer area for cosmic ray energies >1020eV could in principle be realized with some hundred antennas. In any case, pathfinder arrays are needed to test the feasibility of these experiments in the not too distant future. Lunar low-frequency arrays are thus a timely option to consider, offering the potential for significant new insights into a wide range of today's crucial scientific topics. This would open up one of the last unexplored frequency domains in the electromagnetic spectrum.

  16. Wake Flow About the Mars Pathfinder Entry Vehicle

    NASA Technical Reports Server (NTRS)

    Mitcheltree, R. A.; Gnoffo, P. A.

    1995-01-01

    A computational approach is used to describe the aerothermodynamics of the Mars Pathfinder vehicle entering the Mars atmosphere at the maximum heating and maximum deceleration points in its trajectory. Ablating and nonablating boundary conditions are developed which produce maximum recombination of CO2 on the surface. For the maximum heating trajectory point, an axisymmetric, nonablating calculation predicts a stagnation-point value for the convective heating of 115 W/cm(exp 2). Radiative heating estimates predict an additional 5-12 W/cm(exp 2) at the stagnation point. Peak convective heating on the afterbody occurs on the vehicle's flat stern with a value of 5.9% of the stagnation value. The forebody flow exhibits chemical nonequilibrium behavior, and the flow is frozen in the near wake. Including ablation injection on the forebody lowers the stagnation-point convective heating 18%.

  17. Creating Magic Squares.

    ERIC Educational Resources Information Center

    Lyon, Betty Clayton

    1990-01-01

    One method of making magic squares using a prolongated square is illustrated. Discussed are third-order magic squares, fractional magic squares, fifth-order magic squares, decimal magic squares, and even magic squares. (CW)

  18. Detection and Characterization of Micrometeoroid Impacts on LISA Pathfinder

    NASA Astrophysics Data System (ADS)

    Hourihane, S.; Littenberg, T.; Baker, J. G.; Pagane, N.; Slutsky, J. P.; Thorpe, J. I.

    2017-12-01

    LISA Pathfinder (LPF) was a joint ESA/NASA technology demonstration mission for the Laser Interferometer Space Antenna (LISA) gravitational wave observatory. LPF, the most sensitive accelerometer ever flown in space, was launched in December 2015 and successfully concluded its mission in July 2017. Due in part to LPFs success, LISA was selected by the European Space Agency for launch in the early 2030s. An ancillary benefit of LPFs capabilities made it a sensitive detector of micrometeoroid impacts. We report on the capabilities of LPF to detect and characterize impacts, and progress towards using those inferences to advance our understanding of the micrometeoroid environment in the solar system. In doing so, we assess the prospect of space-based gravitational wave observatories as micrometeoroid detection instruments.

  19. In-orbit performance of the LISA Pathfinder drag-free and attitude control system

    NASA Astrophysics Data System (ADS)

    Schleicher, A.; Ziegler, T.; Schubert, R.; Brandt, N.; Bergner, P.; Johann, U.; Fichter, W.; Grzymisch, J.

    2018-04-01

    LISA Pathfinder is a technology demonstrator mission that was funded by the European Space Agency and that was launched on December 3, 2015. LISA Pathfinder has been conducting experiments to demonstrate key technologies for the gravitational wave observatory LISA in its operational orbit at the L1 Lagrange point of the Earth-Sun system until final switch off on July 18, 2017. These key technologies include the inertial sensors, the optical metrology system, a set of µ-propulsion cold gas thrusters and in particular the high performance drag-free and attitude control system (DFACS) that controls the spacecraft in 15 degrees of freedom during its science phase. The main goal of the DFACS is to shield the two test masses inside the inertial sensors from all external disturbances to achieve a residual differential acceleration between the two test masses of less than 3 × 10-14 m/s2/√Hz over the frequency bandwidth of 1-30 mHz. This paper focuses on two important aspects of the DFACS that has been in use on LISA Pathfinder: the DFACS Accelerometer mode and the main DFACS Science mode. The Accelerometer mode is used to capture the test masses after release into free flight from the mechanical grabbing mechanism. The main DFACS Science Mode is used for the actual drag-free science operation. The DFACS control system has very strong interfaces with the LISA Technology Package payload which is a key aspect to master the design, development, and analysis of the DFACS. Linear as well as non-linear control methods are applied. The paper provides pre-flight predictions for the performance of both control modes and compares these predictions to the performance that is currently achieved in-orbit. Some results are also discussed for the mode transitions up to science mode, but the focus of the paper is on the Accelerometer mode performance and on the performance of the Science mode in steady state. Based on the achieved results, some lessons learnt are formulated to extend

  20. Using Squares to Sum Squares

    ERIC Educational Resources Information Center

    DeTemple, Duane

    2010-01-01

    Purely combinatorial proofs are given for the sum of squares formula, 1[superscript 2] + 2[superscript 2] + ... + n[superscript 2] = n(n + 1) (2n + 1) / 6, and the sum of sums of squares formula, 1[superscript 2] + (1[superscript 2] + 2[superscript 2]) + ... + (1[superscript 2] + 2[superscript 2] + ... + n[superscript 2]) = n(n + 1)[superscript 2]…

  1. Mammographic screening practices among Chinese-Australian women.

    PubMed

    Kwok, Cannas; Fethney, Judith; White, Kate

    2012-03-01

    To report mammographic screening practice among Chinese-Australian women, and to examine the relationship between demographic characteristics, acculturation factors (English proficiency and length of stay in Australia), cultural beliefs, and having a mammogram as recommended. Cross-sectional and descriptive. The study was conducted in 2009 in Sydney, Australia. Of 988 Chinese-Australian women over 18 years of age invited to participate in the study, 785 (79%) completed and returned the questionnaire. Of these women, 320 (40.8%) were in the target age range of 50 to 69 years. The Chinese Breast Cancer Screening Beliefs Questionnaire (CBCSB) was used as a data collection instrument. Analysis included descriptive statistics, bivariate analysis using chi-square and t tests, and logistic regression. Of the 320 women in the targeted age range of 50 to 69 years, 238 (74.4%) had a mammogram as recommended biannually. Being married-de facto, in the 60 to 69 age group, and speaking Cantonese at home were positively associated with women's mammographic screening practice. However, no statistically significant differences in acculturation factors and having a mammogram as recommended were found. In terms of CBCSB score, women who had mammograms as recommended had more positive attitudes toward health checkups and perceived fewer barriers to mammographic screening. Effort should be focused on specific subgroups of Chinese-Australian women in order to fully understand the barriers involved in participating in mammographic screening. Nurses can use the findings from the present study to design culturally sensitive breast cancer screening programs to encourage women's participation in mammography. © 2011 Sigma Theta Tau International.

  2. Elucidating dark energy with future 21 cm observations at the epoch of reionization

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

    Kohri, Kazunori; Oyama, Yoshihiko; Sekiguchi, Toyokazu

    2017-02-01

    We investigate how precisely we can determine the nature of dark energy such as the equation of state (EoS) and its time dependence by using future observations of 21 cm fluctuations at the epoch of reionization (06.8∼< z ∼<1) such as Square Kilometre Array (SKA) and Omniscope in combination with those from cosmic microwave background, baryon acoustic oscillation, type Ia supernovae and direct measurement of the Hubble constant. We consider several parametrizations for the EoS and find that future 21 cm observations will be powerful in constraining models of dark energy, especially when its EoS varies at high redshifts.

  3. ELMO Bumpy Square proposal

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

    Dory, R.A.; Uckan, N.A.; Ard, W.B.

    The ELMO Bumpy Square (EBS) concept consists of four straight magnetic mirror arrays linked by four high-field corner coils. Extensive calculations show that this configuration offers major improvements over the ELMO Bumpy Torus (EBT) in particle confinement, heating, transport, ring production, and stability. The components of the EBT device at Oak Ridge National Laboratory can be reconfigured into a square arrangement having straight sides composed of EBT coils, with new microwave cavities and high-field corners designed and built for this application. The elimination of neoclassical convection, identified as the dominant mechanism for the limited confinement in EBT, will give themore » EBS device substantially improved confinement and the flexibility to explore the concepts that produce this improvement. The primary goals of the EBS program are twofold: first, to improve the physics of confinement in toroidal systems by developing the concepts of plasma stabilization using the effects of energetic electrons and confinement optimization using magnetic field shaping and electrostatic potential control to limit particle drift, and second, to develop bumpy toroid devices as attractive candidates for fusion reactors. This report presents a brief review of the physics analyses that support the EBS concept, discussions of the design and expected performance of the EBS device, a description of the EBS experimental program, and a review of the reactor potential of bumpy toroid configurations. Detailed information is presented in the appendices.« less

  4. Experiments and Spectral Studies of Martian Volcanic Rocks: Implications for the Origin of Pathfinder Rocks and Soils

    NASA Technical Reports Server (NTRS)

    Rutherford, Malcolm J.; Mustard, Jack; Weitz, Catherine

    2002-01-01

    The composition and spectral properties of the Mars Pathfinder rocks and soils together with the identification of basaltic and andesitic Mars terrains based on Thermal Emission Spectrometer (TES) data raised interesting questions regarding the nature and origin of Mars surface rocks. We have investigated the following questions: (1) are the Pathfinder rocks igneous and is it possible these rocks could have formed by known igneous processes, such as equilibrium or fractional crystallization, operating within SNC magmas known to exist on Mars? If it is possible, what P (depth) and PH2O conditions are required? (2) whether TES-based interpretations of plagioclase-rich basalt and andesitic terrains in the south and north regions of Mars respectively are unique. Are the surface compositions of these regions plagioclase-rich, possibly indicating the presence of old AI-rich crust of Mars, or are the spectra being affected by something like surface weathering processes that might determine the spectral pyroxene to plagioclase ratio?

  5. Radio Frequency Interference Detection using Machine Learning.

    NASA Astrophysics Data System (ADS)

    Mosiane, Olorato; Oozeer, Nadeem; Aniyan, Arun; Bassett, Bruce A.

    2017-05-01

    Radio frequency interference (RFI) has plagued radio astronomy which potentially might be as bad or worse by the time the Square Kilometre Array (SKA) comes up. RFI can be either internal (generated by instruments) or external that originates from intentional or unintentional radio emission generated by man. With the huge amount of data that will be available with up coming radio telescopes, an automated aproach will be required to detect RFI. In this paper to try automate this process we present the result of applying machine learning techniques to cross match RFI from the Karoo Array Telescope (KAT-7) data. We found that not all the features selected to characterise RFI are always important. We further investigated 3 machine learning techniques and conclude that the Random forest classifier performs with a 98% Area Under Curve and 91% recall in detecting RFI.

  6. News and Views: Diamond is new head of SKA; Did you read our `A&G' mobile issue? BBC writer wins astro journalism prize; Kavli prize recognizes work on Kuiper Belt objects

    NASA Astrophysics Data System (ADS)

    2012-10-01

    Philip Diamond will become director general of the Square Kilometre Array this month, moving from Australia to the new SKA headquarters at Jodrell Bank Radio Observatory. Technology writer Katia Moskvitch has won the first European Astronomy Journalism Prize for her series of articles on the Very Large Telescope at Paranal, Chile. Moskvitch will be the guest of the ESO at the inauguration of the Atacama Large Millimeter/submillimeter Array (ALMA) in the Atacama desert in March 2013. The 2012 Kavli Prize in Astrophysics is shared between David C Jewitt (University of California, USA), Jane X Luu (Massachusetts Institute of Technology, Lincoln Laboratory, USA), and Michael E Brown (California Institute of Technology, USA) “for discovering and characterizing the Kuiper Belt and its largest members, work that led to a major advance in the understanding of the history of our planetary system”.

  7. Frequency-wavenumber processing for infrasound distributed arrays.

    PubMed

    Costley, R Daniel; Frazier, W Garth; Dillion, Kevin; Picucci, Jennifer R; Williams, Jay E; McKenna, Mihan H

    2013-10-01

    The work described herein discusses the application of a frequency-wavenumber signal processing technique to signals from rectangular infrasound arrays for detection and estimation of the direction of travel of infrasound. Arrays of 100 sensors were arranged in square configurations with sensor spacing of 2 m. Wind noise data were collected at one site. Synthetic infrasound signals were superposed on top of the wind noise to determine the accuracy and sensitivity of the technique with respect to signal-to-noise ratio. The technique was then applied to an impulsive event recorded at a different site. Preliminary results demonstrated the feasibility of this approach.

  8. Babinet's principle and the band structure of surface waves on patterned metal arrays

    NASA Astrophysics Data System (ADS)

    Edmunds, J. D.; Taylor, M. C.; Hibbins, A. P.; Sambles, J. R.; Youngs, I. J.

    2010-05-01

    The microwave response of an array of square metal patches and its complementary structure, an array of square holes, has been experimentally studied. The resonant phenomena, which yield either enhanced transmission or reflection, are attributed to the excitation of diffractively coupled surface waves. The band structure of these surface modes has been quantified for both p-(transverse magnetic) and s-(transverse electric) polarized radiation and is found to be dependent on the periodicity of the electric and magnetic fields on resonance. The results are in excellent accord with predictions from finite element method modeling and the electromagnetic form of Babinet's principle [Babinet, C. R. Acad. Sci. 4, 638 (1837)].

  9. Far infrared through millimeter backshort-under-grid arrays

    NASA Astrophysics Data System (ADS)

    Allen, Christine A.; Abrahams, John; Benford, Dominic J.; Chervenak, James A.; Chuss, David T.; Staguhn, Johannes G.; Miller, Timothy M.; Moseley, S. Harvey; Wollack, Edward J.

    2006-06-01

    We are developing a large-format, versatile, bolometer array for a wide range of infrared through millimeter astronomical applications. The array design consists of three key components - superconducting transition edge sensor bolometer arrays, quarter-wave reflective backshort grids, and Superconducting Quantum Interference Device (SQUID) multiplexer readouts. The detector array is a filled, square grid of bolometers with superconducting sensors. The backshort arrays are fabricated separately and are positioned in the etch cavities behind the detector grid. The grids have unique three-dimensional interlocking features micromachined into the walls for positioning and mechanical stability. The ultimate goal of the program is to produce large-format arrays with background-limited sensitivity, suitable for a wide range of wavelengths and applications. Large-format (kilopixel) arrays will be directly indium bump bonded to a SQUID multiplexer circuit. We have produced and tested 8×8 arrays of 1 mm detectors to demonstrate proof of concept. 8×16 arrays of 2 mm detectors are being produced for a new Goddard Space Flight Center instrument. We have also produced models of a kilopixel detector grid and dummy multiplexer chip for bump bonding development. We present detector design overview, several unique fabrication highlights, and assembly technologies.

  10. New Insights into the Geology of the Mars Pathfinder Landing Site from Spectral and Morphologic Analysis of the 12-Color Superpan Panorama

    NASA Technical Reports Server (NTRS)

    Murchie, S.; Barnouin-Jha, O.; Barnouin-Jha, K.; Bishop, J.; Johnson, J.; McSween, H.; Morris, R.

    2003-01-01

    New analyses of rocks and soils at the Mars Pathfinder landing site have been completed using the full Imager for Mars Pathfinder (IMP) 12- color SuperPan panorama. These revise early conclusions that rocks at the landing site are a single lithology coated only by windblown dust. We conclude instead that there is also a second lithology in addition to the dominant gray rock, and that it is consistent with highlands material excavated from beneath a thin veneer of northern plains; that many rocks have cemented coatings that formed during an early, probably wetter climate; and that young rocks excavated after coating formation ceased are mainly breccias or conglomerates.

  11. A Ka-Band (26 GHz) Circularly Polarized 2x2 Microstrip Patch Sub-Array with Compact Feed

    NASA Technical Reports Server (NTRS)

    Chrysler, Andrew; Furse, Cynthia; Simons, Rainee N.; Miranda, Felix A.

    2017-01-01

    A Ka-band (26 GHz) 2x2 array consisting of square-shaped microstrip patch antenna elements with two truncated corners for circular polarization (CP) is presented. The array is being developed for satellite communications.

  12. AGU Pathfinder: Career and Professional Development Resources for Earth and Space Scientists

    NASA Astrophysics Data System (ADS)

    Harwell, D. E.; Asher, P. M.; Hankin, E. R.; Janick, N. G.; Marasco, L.

    2017-12-01

    The American Geophysical Union (AGU) is committed to inspiring and educating present and future generations of diverse, innovative, and creative Earth and space scientists. To meet our commitment, AGU provides career and educational resources, webinars, mentoring, and support for students and professionals at each level of development to reduce barriers to achievement and to promote professional advancement. AGU is also working with other organizations and educational institutions to collaborate on projects benefiting the greater geoscience community. The presentation will include an overview of current Pathfinder efforts, collaborative efforts, and an appeal for additional partnerships.

  13. Method and apparatus for enhancing vortex pinning by conformal crystal arrays

    DOEpatents

    Janko, Boldizsar; Reichhardt, Cynthia; Reichhardt, Charles; Ray, Dipanjan

    2015-07-14

    Disclosed is a method and apparatus for strongly enhancing vortex pinning by conformal crystal arrays. The conformal crystal array is constructed by a conformal transformation of a hexagonal lattice, producing a non-uniform structure with a gradient where the local six-fold coordination of the pinning sites is preserved, and with an arching effect. The conformal pinning arrays produce significantly enhanced vortex pinning over a much wider range of field than that found for other vortex pinning geometries with an equivalent number of vortex pinning sites, such as random, square, and triangular.

  14. Quantum superconductor-metal transition in a proximity array.

    PubMed

    Feigel'man, M V; Larkin, A I; Skvortsov, M A

    2001-02-26

    A theory of the zero-temperature superconductor-metal transition is developed for an array of superconductive islands (of size d) coupled via a disordered two-dimensional conductor with the dimensionless conductance g = Planck's over 2 pi/e(2)R(square)>1. At T = 0 the macroscopically superconductive state of the array with lattice spacing b>d is destroyed at g

  15. Rock Statistics at the Mars Pathfinder Landing Site, Roughness and Roving on Mars

    NASA Technical Reports Server (NTRS)

    Haldemann, A. F. C.; Bridges, N. T.; Anderson, R. C.; Golombek, M. P.

    1999-01-01

    Several rock counts have been carried out at the Mars Pathfinder landing site producing consistent statistics of rock coverage and size-frequency distributions. These rock statistics provide a primary element of "ground truth" for anchoring remote sensing information used to pick the Pathfinder, and future, landing sites. The observed rock population statistics should also be consistent with the emplacement and alteration processes postulated to govern the landing site landscape. The rock population databases can however be used in ways that go beyond the calculation of cumulative number and cumulative area distributions versus rock diameter and height. Since the spatial parameters measured to characterize each rock are determined with stereo image pairs, the rock database serves as a subset of the full landing site digital terrain model (DTM). Insofar as a rock count can be carried out in a speedier, albeit coarser, manner than the full DTM analysis, rock counting offers several operational and scientific products in the near term. Quantitative rock mapping adds further information to the geomorphic study of the landing site, and can also be used for rover traverse planning. Statistical analysis of the surface roughness using the rock count proxy DTM is sufficiently accurate when compared to the full DTM to compare with radar remote sensing roughness measures, and with rover traverse profiles.

  16. Observations at the Mars Pathfinder site: Do they provide "unequivocal" evidence of catastrophic flooding?

    USGS Publications Warehouse

    Chapman, M.G.; Kargel, J.S.

    1999-01-01

    After Mars Pathfinder landed at the mouth of Ares Vallis, a large channel that drains into the Chryse Planitia basin, the mission reports unanimously supported the interpretation that the lander site is the locus of catastrophic flooding by noting that all aspects of the scene are consistent with this interpretation. However, alternatives cannot be ruled out by any site observations, as all aspects of the scene are equally consistent with other interpretations of origin, namely, ice and mass-flow processes subsequently modified by wind erosion. The authors discuss alternative explanations for the geologic history of the channel based on a regional view of the circum-Chryse channels from Viking images (our best broad-scale information to date) and the local view from the recent Pathfinder landing site. Mega-indicators of channel origin, the regional geomorphology, geology, and planetary climatic conditions, taken together suggest some combination of flood, mass flow, glacial, and eolian processes. The macro-indicators of channel origin (sedimentologic) are also not indicative of one process of emplacement, either as single criteria or taken cumulatively. Finally, the micro-indicators of channel origin (geochemical and mineralogic composition) do not provide very tight constraints on the deposits' possible origins other than that water was in some way involved.

  17. A 5 meter range non-planar CMUT array for Automotive Collision Avoidance

    NASA Astrophysics Data System (ADS)

    Hernandez Aguirre, Jonathan

    A discretized hyperbolic paraboloid geometry capacitive micromachined ultrasonic transducer (CMUT) array has been designed and fabricated for automotive collision avoidance. The array is designed to operate at 40 kHz, beamwidth of 40° with a maximum sidelobe intensity of -10dB. An SOI based fabrication technology has been used for the 5x5 array with 5 sensing surfaces along each x and y axis and 7 elevation levels. An assembly and packaging technique has been developed to realize the non-planar geometry in a PGA-68 package. A highly accurate mathematical method has been presented for analytical characterization of capacitive micromachined ultrasonic transducers (CMUTs) built with square diaphragms. The method uses a new two-dimensional polynomial function to more accurately predict the deflection curve of a multilayer square diaphragm subject to both mechanical and electrostatic pressure and a new capacitance model that takes into account the contribution of the fringing field capacitances.

  18. Analysing the 21 cm signal from the epoch of reionization with artificial neural networks

    NASA Astrophysics Data System (ADS)

    Shimabukuro, Hayato; Semelin, Benoit

    2017-07-01

    The 21 cm signal from the epoch of reionization should be observed within the next decade. While a simple statistical detection is expected with Square Kilometre Array (SKA) pathfinders, the SKA will hopefully produce a full 3D mapping of the signal. To extract from the observed data constraints on the parameters describing the underlying astrophysical processes, inversion methods must be developed. For example, the Markov Chain Monte Carlo method has been successfully applied. Here, we test another possible inversion method: artificial neural networks (ANNs). We produce a training set that consists of 70 individual samples. Each sample is made of the 21 cm power spectrum at different redshifts produced with the 21cmFast code plus the value of three parameters used in the seminumerical simulations that describe astrophysical processes. Using this set, we train the network to minimize the error between the parameter values it produces as an output and the true values. We explore the impact of the architecture of the network on the quality of the training. Then we test the trained network on the new set of 54 test samples with different values of the parameters. We find that the quality of the parameter reconstruction depends on the sensitivity of the power spectrum to the different parameters at a given redshift, that including thermal noise and sample variance decreases the quality of the reconstruction and that using the power spectrum at several redshifts as an input to the ANN improves the quality of the reconstruction. We conclude that ANNs are a viable inversion method whose main strength is that they require a sparse exploration of the parameter space and thus should be usable with full numerical simulations.

  19. DSMC Simulations of Blunt Body Flows for Mars Entries: Mars Pathfinder and Mars Microprobe Capsules

    NASA Technical Reports Server (NTRS)

    Moss, James N.; Wilmoth, Richard G.; Price, Joseph M.

    1997-01-01

    The hypersonic transitional flow aerodynamics of the Mars Pathfinder and Mars Microprobe capsules are simulated with the direct simulation Monte Carlo method. Calculations of axial, normal, and static pitching coefficients were obtained over an angle of attack range comparable to actual flight requirements. Comparisons are made with modified Newtonian and free-molecular-flow calculations. Aerothermal results were also obtained for zero incidence entry conditions.

  20. Gallium arsenide quantum well-based far infrared array radiometric imager

    NASA Technical Reports Server (NTRS)

    Forrest, Kathrine A.; Jhabvala, Murzy D.

    1991-01-01

    We have built an array-based camera (FIRARI) for thermal imaging (lambda = 8 to 12 microns). FIRARI uses a square format 128 by 128 element array of aluminum gallium arsenide quantum well detectors that are indium bump bonded to a high capacity silicon multiplexer. The quantum well detectors offer good responsivity along with high response and noise uniformity, resulting in excellent thermal images without compensation for variation in pixel response. A noise equivalent temperature difference of 0.02 K at a scene temperature of 290 K was achieved with the array operating at 60 K. FIRARI demonstrated that AlGaAS quantum well detector technology can provide large format arrays with performance superior to mercury cadmium telluride at far less cost.

  1. On Detecting Repetition from Fast Radio Bursts

    NASA Astrophysics Data System (ADS)

    Connor, Liam; Petroff, Emily

    2018-07-01

    Fast radio bursts (FRBs) are bright, millisecond-duration radio pulses of unknown origin. To date, only one (FRB 121102) out of several dozen has been seen to repeat, though the extent to which it is exceptional remains unclear. We discuss detecting repetition from FRBs, which will be very important for understanding their physical origin, and which also allows for host galaxy localization. We show how the combination of instrument sensitivity, beam shapes, and individual FRB luminosity functions affect the detection of sources with repetition that is not necessarily described by a homogeneous Poisson process. We demonstrate that the Canadian Hydrogen Intensity Mapping Experiment (CHIME) could detect many new repeating FRBs for which host galaxies could be subsequently localized using other interferometers, but it will not be an ideal instrument for monitoring FRB 121102. If the luminosity distributions of repeating FRBs are given by power laws with significantly more dim than bright bursts, CHIME’s repetition discoveries could preferentially come not from its own discoveries, but from sources first detected with lower-sensitivity instruments like the Australian Square Kilometer Array Pathfinder in fly’s eye mode. We then discuss observing strategies for upcoming surveys, and advocate following up sources at approximately regular intervals and with telescopes of higher sensitivity when possible. Finally, we discuss doing pulsar-like periodicity searching on FRB follow-up data, based on the idea that while most pulses are undetectable, folding on an underlying rotation period could reveal the hidden signal.

  2. Structural analyses of the JPL Mars Pathfinder impact

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

    Gwinn, K.W.

    1994-12-31

    The purpose of this paper is to demonstrate that finite element analysis can be used in the design process for high performance fabric structures. These structures exhibit extreme geometric nonlinearity; specifically, the contact and interaction of fabric surfaces with the large deformation which necessarily results from membrane structures introduces great complexity to analyses of this type. All of these features are demonstrated here in the analysis of the Jet Propulsion Laboratory (JPL) Mars Pathfinder impact onto Mars. This lander system uses airbags to envelope the lander experiment package, protecting it with large deformation upon contact. Results from the analysis showmore » the stress in the fabric airbags, forces in the internal tendon support system, forces in the latches and hinges which allow the lander to deploy after impact, and deceleration of the lander components. All of these results provide the JPL engineers with design guidance for the success of this novel lander system.« less

  3. Structural analyses of the JPL Mars Pathfinder impact

    NASA Astrophysics Data System (ADS)

    Gwinn, Kenneth W.

    The purpose of this paper is to demonstrate that finite element analysis can be used in the design process for high performance fabric structures. These structures exhibit extreme geometric nonlinearity; specifically, the contact and interaction of fabric surfaces with the large deformation which necessarily results from membrane structures introduces great complexity to analyses of this type. All of these features are demonstrated here in the analysis of the Jet Propulsion Laboratory (JPL) Mars Pathfinder impact onto Mars. This lander system uses airbags to envelope the lander experiment package, protecting it with large deformation upon contact. Results from the analysis show the stress in the fabric airbags, forces in the internal tendon support system, forces in the latches and hinges which allow the lander to deploy after impact, and deceleration of the lander components. All of these results provide the JPL engineers with design guidance for the success of this novel lander system.

  4. Pathfinding the Flight Advanced Stirling Convertor Design with the ASC-E3

    NASA Technical Reports Server (NTRS)

    Wong, Wayne A.; Wilson, Kyle; Smith, Eddie; Collins, Josh

    2012-01-01

    The Advanced Stirling Convertor (ASC) was initially developed by Sunpower, Inc. under contract to NASA Glenn Research Center (GRC) as a technology development project. The ASC technology fulfills NASA's need for high efficiency power convertors for future Radioisotope Power Systems (RPS). Early successful technology demonstrations between 2003 to 2005 eventually led to the expansion of the project including the decision in 2006 to use the ASC technology on the Advanced Stirling Radioisotope Generator (ASRG). Sunpower has delivered 22 ASC convertors of progressively mature designs to date to GRC. Currently, Sunpower with support from GRC, Lockheed Martin Space System Company (LMSSC), and the Department of Energy (DOE) is developing the flight ASC-F in parallel with the ASC-E3 pathfinders. Sunpower will deliver four pairs of ASC-E3 convertors to GRC which will be used for extended operation reliability assessment, independent validation and verification testing, system interaction tests, and to support LMSSC controller verification. The ASC-E3 and -F convertors are being built to the same design and processing documentation and the same product specification. The initial two pairs of ASC-E3 are built before the flight units and will validate design and processing changes prior to implementation on the ASC-F flight convertors. This paper provides a summary on development of the ASC technology and the status of the ASC-E3 build and how they serve the vital pathfinder role ahead of the flight build for ASRG. The ASRG is part of two of the three candidate missions being considered for selection for the Discovery 12 mission.

  5. Multistep hierarchical self-assembly of chiral nanopore arrays

    PubMed Central

    Kim, Hanim; Lee, Sunhee; Shin, Tae Joo; Korblova, Eva; Walba, David M.; Clark, Noel A.; Lee, Sang Bok; Yoon, Dong Ki

    2014-01-01

    A series of simple hierarchical self-assembly steps achieve self-organization from the centimeter to the subnanometer-length scales in the form of square-centimeter arrays of linear nanopores, each one having a single chiral helical nanofilament of large internal surface area and interfacial interactions based on chiral crystalline molecular arrangements. PMID:25246585

  6. Exploring MEDLINE Space with Random Indexing and Pathfinder Networks

    PubMed Central

    Cohen, Trevor

    2008-01-01

    The integration of disparate research domains is a prerequisite for the success of the translational science initiative. MEDLINE abstracts contain content from a broad range of disciplines, presenting an opportunity for the development of methods able to integrate the knowledge they contain. Latent Semantic Analysis (LSA) and related methods learn human-like associations between terms from unannotated text. However, their computational and memory demands limits their ability to address a corpus of this size. Furthermore, visualization methods previously used in conjunction with LSA have limited ability to define the local structure of the associative networks LSA learns. This paper explores these issues by (1) processing the entire MEDLINE corpus using Random Indexing, a variant of LSA, and (2) exploring learned associations using Pathfinder Networks. Meaningful associations are inferred from MEDLINE, including a drug-disease association undetected by PUBMED search. PMID:18999236

  7. Exploring MEDLINE space with random indexing and pathfinder networks.

    PubMed

    Cohen, Trevor

    2008-11-06

    The integration of disparate research domains is a prerequisite for the success of the translational science initiative. MEDLINE abstracts contain content from a broad range of disciplines, presenting an opportunity for the development of methods able to integrate the knowledge they contain. Latent Semantic Analysis (LSA) and related methods learn human-like associations between terms from unannotated text. However, their computational and memory demands limits their ability to address a corpus of this size. Furthermore, visualization methods previously used in conjunction with LSA have limited ability to define the local structure of the associative networks LSA learns. This paper explores these issues by (1) processing the entire MEDLINE corpus using Random Indexing, a variant of LSA, and (2) exploring learned associations using Pathfinder Networks. Meaningful associations are inferred from MEDLINE, including a drug-disease association undetected by PUBMED search.

  8. Mars Pathfinder and the exploration of southern Amazonis Planitia

    NASA Technical Reports Server (NTRS)

    Barlow, Nadine G.

    1994-01-01

    The southern region of Amazonis Planitia provides a variety of target terrains for a roving vehicle such as the Mars Pathfinder Mission. A landing site is proposed at 4 deg N latitude 162 deg W longitude. This area has a reference altitude of between 0 and -1 km and consists of relatively smooth Amazonian-aged deposits within the entire 100 x 200 km landing ellipse. The proposed landing site is within the Upper Member Medusae Fossae Formation deposits (Amu) and near the boundary with Middle Member Medusae Fossae Formation deposits (Amm) and Member 1 Arcadia Formation plains (Aa(sub 1)). Slightly further afield are 107-km-diameter Nicholson crater, its ejecta deposits, and knobby terrain of proposed Hesperian age (HNu). Depending on the exact landing site of the spacecraft and the traverse distance of the rover, these materials also may be sampled.

  9. Emission and propagation of Saturn kilometric radiation: Magnetoionic modes, beaming pattern, and polarization state

    NASA Astrophysics Data System (ADS)

    Lamy, L.; Cecconi, B.; Zarka, P.; Canu, P.; Schippers, P.; Kurth, W. S.; Mutel, R. L.; Gurnett, D. A.; Menietti, D.; Louarn, P.

    2011-04-01

    The Cassini mission crossed the source region of the Saturn kilometric radiation (SKR) on 17 October 2008. On this occasion, the Radio and Plasma Wave Science (RPWS) experiment detected both local and distant radio sources, while plasma parameters were measured in situ by the magnetometer and the Cassini Plasma Spectrometer. A goniopolarimetric inversion was applied to RPWS three-antenna electric measurements to determine the wave vector k and the complete state of polarization of detected waves. We identify broadband extraordinary (X) mode as well as narrowband ordinary (O) mode SKR at low frequencies. Within the source region, SKR is emitted just above the X mode cutoff frequency in a hot plasma, with a typical electron-to-wave energy conversion efficiency of ˜1% (2% peak). The knowledge of the k vector is then used to derive the locus of SKR sources in the kronian magnetosphere, which shows X and O components emanating from the same regions. We also compute the associated beaming angle at the source θ‧ = (k, -B) either from (1) in situ measurements or a model of the magnetic field vector (for local to distant sources) or (2) polarization measurements (for local sources). Obtained results, similar for both modes, suggest quasi-perpendicular emission for local sources, whereas the beaming pattern of distant sources appears as a hollow cone with a frequency-dependent constant aperture angle: θ‧ = 75° ± 15° below 300 kHz, decreasing at higher frequencies to reach θ‧ (1000 kHz) = 50° ± 25°. Finally, we investigate quantitatively the SKR polarization state, observed to be strongly elliptical at the source, and quasi-purely circular for sources located beyond approximately two kronian radii. We show that conditions of weak mode coupling are achieved along the raypath, under which the magnetoionic theory satisfactorily describes the evolution of the observed polarization. These results are analyzed comparatively with the auroral kilometric radiation at

  10. Prospects for gravitational wave astronomy with next generation large-scale pulsar timing arrays

    NASA Astrophysics Data System (ADS)

    Wang, Yan; Mohanty, Soumya D.

    2018-02-01

    Next generation radio telescopes, namely the Five-hundred-meter Aperture Spherical Telescope (FAST) and the Square Kilometer Array (SKA), will revolutionize the pulsar timing arrays (PTAs) based gravitational wave (GW) searches. We review some of the characteristics of FAST and SKA, and the resulting PTAs, that are pertinent to the detection of gravitational wave signals from individual supermassive black hole binaries.

  11. Overlap Areas of a Square Box on a Square Mesh

    DTIC Science & Technology

    2017-04-01

    ARL-TN-0818 ● APR 2017 US Army Research Laboratory Overlap Areas of a Square Box on a Square Mesh by James U Cazamias...originator. ARL-TN-0818 ● APR 2017 US Army Research Laboratory Overlap Areas of a Square Box on a Square Mesh by James U Cazamias...

  12. Multilayer DNA Origami Packed on a Square Lattice

    PubMed Central

    Ke, Yonggang; Douglas, Shawn M.; Liu, Minghui; Sharma, Jaswinder; Cheng, Anchi; Leung, Albert; Liu, Yan; Shih, William M.; Yan, Hao

    2009-01-01

    Molecular self-assembly using DNA as a structural building block has proven to be an efficient route to the construction of nanoscale objects and arrays of increasing complexity. Using the remarkable “scaffolded DNA origami” strategy, Rothemund demonstrated that a long single-stranded DNA from a viral genome (M13) can be folded into a variety of custom two-dimensional (2D) shapes using hundreds of short synthetic DNA molecules as staple strands. More recently, we generalized a strategy to build custom-shaped, three-dimensional (3D) objects formed as pleated layers of helices constrained to a honeycomb lattice, with precisely controlled dimensions ranging from 10 to 100 nm. Here we describe a more compact design for 3D origami, with layers of helices packed on a square lattice, that can be folded successfully into structures of designed dimensions in a one-step annealing process, despite the increased density of DNA helices. A square lattice provides a more natural framework for designing rectangular structures, the option for a more densely packed architecture, and the ability to create surfaces that are more flat than is possible with the honeycomb lattice. Thus enabling the design and construction of custom 3D shapes from helices packed on a square lattice provides a general foundational advance for increasing the versatility and scope of DNA nanotechnology. PMID:19807088

  13. Copy Number Variations of TBK1 in Australian Patients With Primary Open-Angle Glaucoma

    PubMed Central

    AWADALLA, MONA S.; FINGERT, JOHN H.; ROOS, BENJAMIN E.; CHEN, SIMON; HOLMES, RICHARD; GRAHAM, STUART L.; CHEHADE, MARK; GALANOPOLOUS, ANNA; RIDGE, BRONWYN; SOUZEAU, EMMANUELLE; ZHOU, TIGER; SIGGS, OWEN M.; HEWITT, ALEX W.; MACKEY, DAVID A.; BURDON, KATHRYN P.; CRAIG, JAMIE E.

    2015-01-01

    PURPOSE To investigate the presence of TBK1 copy number variations in a large, well-characterized Australian cohort of patients with glaucoma comprising both normal-tension glaucoma and high-tension glaucoma cases. DESIGN A retrospective cohort study. METHODS DNA samples from patients with normal-tension glaucoma and high-tension glaucoma and unaffected controls were screened for TBK1 copy number variations using real-time quantitative polymerase chain reaction. Samples with additional copies of the TBK1 gene were further tested using custom comparative genomic hybridization arrays. RESULTS Four out of 334 normal-tension glaucoma cases (1.2%) were found to carry TBK1 copy number variations using quantitative polymerase chain reaction. One extra dose of the TBK1 gene (duplication) was detected in 3 normal-tension glaucoma patients, while 2 extra doses of the gene (triplication) were detected in a fourth normal-tension glaucoma patient. The results were further confirmed by custom comparative genomic hybridization arrays. Further, the TBK1 copy number variation segregated with normal-tension glaucoma in the family members of the probands, showing an autosomal dominant pattern of inheritance. No TBK1 copy number variations were detected in 1045 Australian patients with high-tension glaucoma or in 254 unaffected controls. CONCLUSION We report the presence of TBK1 copy number variations in our Australian normal-tension glaucoma cohort, including the first example of more than 1 extra copy of this gene in glaucoma patients (gene triplication). These results confirm TBK1 to be an important cause of normal-tension glaucoma, but do not suggest common involvement in high-tension glaucoma. PMID:25284765

  14. Apical root canal transportation of different pathfinding systems and their effects on shaping ability of ProTaper Next

    PubMed Central

    Türker, Sevinç-Aktemur

    2015-01-01

    Background This study aimed to compare glide path preparation of different pathfinding systems and their effects on the apical transportation of ProTaper Next (Dentsply Maillefer, Ballaigues, Switzerland) in mesial root canals of extracted human mandibular molars, using digital subtraction radiography. Material and Methods The mesial canals of 40 mandibular first molars (with curvature angles between 25° and 35°) were selected for this study. The specimens were divided randomly into 4 groups with 10 canals each. Glide paths were created in group 1 with #10, #15 and #20 K-type (Dentsply Maillefer, Ballaigues, Switzerland) stainless steel manual files; in group 2 with Path-File (Dentsply Maillefer) #1, #2, and #3 and in group 3 with #16 ProGlider (Dentsply Maillefer) rotary instruments; in group 4 no glide paths were created. All canals were instrumented up to ProTaper Next X2 to the working length. A double digital radiograph technique was used, pre and post-instrumentation, to assess whether apical transportation and/or aberration in root canal morphology occurred. Instrument failures were also recorded. The data were analyzed statistically using ANOVA and Tukey tests (p<0.05). Results No significant differences were found among groups regarding apical transportation (p>0.05). Two ProTaper Next instruments failed in-group 4. Conclusions Within the parameters of this study, there was no difference between the performance of path-finding files and ProTaper Next system maintained root canal curvature well and was safe to use either with path-finding files or alone. Key words:Glide path, PathFile, ProGlider, ProTaper Next, transportation. PMID:26330936

  15. Australian transport index thesaurus

    DOT National Transportation Integrated Search

    2007-12-01

    This Thesaurus is designed to assist Australian librarians and researchers to access Australian and overseas : literature on transport and roads. Preferred terms have largely been chosen to reflect Australian usage. Terms : from the thesaurus are use...

  16. Microchannel cross load array with dense parallel input

    DOEpatents

    Swierkowski, Stefan P.

    2004-04-06

    An architecture or layout for microchannel arrays using T or Cross (+) loading for electrophoresis or other injection and separation chemistry that are performed in microfluidic configurations. This architecture enables a very dense layout of arrays of functionally identical shaped channels and it also solves the problem of simultaneously enabling efficient parallel shapes and biasing of the input wells, waste wells, and bias wells at the input end of the separation columns. One T load architecture uses circular holes with common rows, but not columns, which allows the flow paths for each channel to be identical in shape, using multiple mirror image pieces. Another T load architecture enables the access hole array to be formed on a biaxial, collinear grid suitable for EDM micromachining (square holes), with common rows and columns.

  17. High redshift signatures in the 21 cm forest due to cosmic string wakes

    NASA Astrophysics Data System (ADS)

    Tashiro, Hiroyuki; Sekiguchi, Toyokazu; Silk, Joseph

    2014-01-01

    Cosmic strings induce minihalo formation in the early universe. The resultant minihalos cluster in string wakes and create a ``21 cm forest'' against the cosmic microwave background (CMB) spectrum. Such a 21 cm forest can contribute to angular fluctuations of redshifted 21 cm signals integrated along the line of sight. We calculate the root-mean-square amplitude of the 21 cm fluctuations due to strings and show that these fluctuations can dominate signals from minihalos due to primordial density fluctuations at high redshift (zgtrsim10), even if the string tension is below the current upper bound, Gμ < 1.5 × 10-7. Our results also predict that the Square Kilometre Array (SKA) can potentially detect the 21 cm fluctuations due to strings with Gμ ≈ 7.5 × 10-8 for the single frequency band case and 4.0 × 10-8 for the multi-frequency band case.

  18. Cloud-Aerosol LIDAR and Infrared Pathfinder Satellite Observation (CALIPSO) Spacecraft: Independent Technical Assessment

    NASA Technical Reports Server (NTRS)

    Gilbrech, Richard J.; McManamen, John P.; Wilson, Timmy R.; Robinson, Frank; Schoren, William R.

    2004-01-01

    CALIPSO is a joint science mission between the CNES, LaRC and GSFC. It was selected as an Earth System Science Pathfinder satellite mission in December 1998 to address the role of clouds and aerosols in the Earth's radiation budget. The spacecraft includes a NASA light detecting and ranging (LIDAR) instrument, a NASA wide-field camera and a CNES imaging infrared radiometer. The scope of this effort was a review of the Proteus propulsion bus design and an assessment of the potential for personnel exposure to hydrazine propellant.

  19. Cloud-Aerosol LIDAR and Infrared Pathfinder Satellite Observation (CALIPSO) Spacecraft: Independent Technical Assessment

    NASA Technical Reports Server (NTRS)

    Gilbrech, Richard J.; McManamen, John P.; Wilson, Timmy R.; Robinson, Frank; Schoren, William R.

    2005-01-01

    CALIPSO is a joint science mission between the CNES, LaRC and GSFC. It was selected as an Earth System Science Pathfinder satellite mission in December 1998 to address the role of clouds and aerosols in the Earth's radiation budget. The spacecraft includes a NASA light detecting and ranging (LIDAR) instrument, a NASA wide-field camera and a CNES imaging infrared radiometer. The scope of this effort was a review of the Proteus propulsion bus design and an assessment of the potential for personnel exposure to hydrazine propellant.

  20. The Politics Are Personal: "The Australian" vs the Australian Curriculum in History

    ERIC Educational Resources Information Center

    Taylor, Tony; Collins, Sue

    2012-01-01

    This article reviews the relationship between the conservative newspaper "The Australian" and the development of a national history curriculum in Australia. The lead author surveyed the major Australian press in the five-year period between 2007 and 2012 and found clear patterns of difference between "The Australian" and other…