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At least 469 records · Page 26

The AuScope Project and Trans-Tasman VLBI

Three 12-meter radio telescopes are being built in Australia (the AuScope project) and one in New Zealand. These facilities will be fully-equipped for undertaking S and X-band geodetic VLBI observations and correlation will take place on a software correlator (part of the AuScope project). All sites are equipped with permanent GPS receivers to provide co-location of several space geodetic techniques. The following scientific tasks of geodesy and astrometry are considered. 1. Improvement and densification of the International Celestial Reference Frame in the southern hemisphere; 2. Improvement of the International Terrestrial Reference Frame in the region; 3. Measurement of intraplate deformation of the Australian tectonic plate.

Lovell, Jim↗

The Wettzell System Monitoring Concept and First Realizations

Automated monitoring of operational system parameters for the geodetic space techniques is becoming more important in order to improve the geodetic data and to ensure the safety and stability of automatic and remote-controlled observations. Therefore, the Wettzell group has developed the system monitoring software, SysMon, which is based on a reliable, remotely-controllable hardware/software realization. A multi-layered data logging system based on a fanless, robust industrial PC with an internal database system is used to collect data from several external, serial, bus, or PCI-based sensors. The internal communication is realized with Remote Procedure Calls (RPC) and uses generative programming with the interface software generator idl2rpc.pl developed at Wettzell. Each data monitoring stream can be configured individually via configuration files to define the logging rates or analog-digital-conversion parameters. First realizations are currently installed at the new laser ranging system at Wettzell to address safety issues and at the VLBI station O Higgins as a meteorological data logger. The system monitoring concept should be realized for the Wettzell radio telescope in the near future.

Ettl, Martin↗

COLD MAGICS - Continuous Local Deformation Monitoring of an Arctic Geodetic Fundamental Station

We describe the experience gained in a project to continuously monitor the local tie at the Geodetic Observatory Ny-Alesund. A PC-controlled robotic total station was used to monitor survey prisms that were attached to survey pillars of the local network and the monuments used for geodetic VLBI and GNSS measurements. The monitoring lasted for seven days and had a temporal resolution of six minutes. The raw angle and distance measurements show clear sinusoidal signatures with a daily period, most strongly for a four-day period with 24 hours of sunshine. The derived topocentric coordinates of the survey prisms attached to the GNSS monument and the VLBI radio telescope act as approximation for the local tie. We detect clear signatures at the mm-level. With the current approach we cannot distinguish between real motion of the prisms and potential thermal influences on the instrument used for the observations. However, the project shows that continuous local tie monitoring is feasible today and in the future can and should be used for all geodetic co-location stations.

Haas, Ruediger↗

NASA Tech Briefs, June 2011

Topics covered include: Wind and Temperature Spectrometry of the Upper Atmosphere in Low-Earth Orbit; Health Monitor for Multitasking, Safety-Critical, Real-Time Software; Stereo Imaging Miniature Endoscope; Early Oscillation Detection Technique for Hybrid DC/DC Converters; Parallel Wavefront Analysis for a 4D Interferometer; Schottky Heterodyne Receivers With Full Waveguide Bandwidth; Carbon Nanofiber-Based, High-Frequency, High-Q, Miniaturized Mechanical Resonators; Ultracapacitor-Based Uninterrupted Power Supply System; Coaxial Cables for Martian Extreme Temperature Environments; Using Spare Logic Resources To Create Dynamic Test Points; Autonomous Coordination of Science Observations Using Multiple Spacecraft; Autonomous Phase Retrieval Calibration; EOS MLS Level 1B Data Processing Software, Version 3; Cassini Tour Atlas Automated Generation; Software Development Standard Processes (SDSP); Graphite Composite Panel Polishing Fixture; Material Gradients in Oxygen System Components Improve Safety; Ridge Waveguide Structures in Magnesium-Doped Lithium Niobate; Modifying Matrix Materials to Increase Wetting and Adhesion; Lightweight Magnetic Cooler With a Reversible Circulator; The Invasive Species Forecasting System; Method for Cleanly and Precisely Breaking Off a Rock Core Using a Radial Compressive Force; Praying Mantis Bending Core Breakoff and Retention Mechanism; Scoring Dawg Core Breakoff and Retention Mechanism; Rolling-Tooth Core Breakoff and Retention Mechanism; Vibration Isolation and Stabilization System for Spacecraft Exercise Treadmill Devices; Microgravity-Enhanced Stem Cell Selection; Diagnosis and Treatment of Neurological Disorders by Millimeter-Wave Stimulation; Passive Vaporizing Heat Sink; Remote Sensing and Quantization of Analog Sensors; Phase Retrieval for Radio Telescope and Antenna Control; Helium-Cooled Black Shroud for Subscale Cryogenic Testing; Receive Mode Analysis and Design of Microstrip Reflectarrays; and Chance-Constrained Guidance With Non-Convex Constraints.

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Fabrication of Spherical Reflectors in Outer Space

A process is proposed for fabrication of lightweight spherical reflectors in outer space for telescopes, radio antennas, and light collectors that would be operated there. The process would obviate the relatively massive substrates and frames needed to support such reflectors in normal Earth gravitation. According to the proposal, fabrication of a reflector would begin with blowing of a bubble to the specified reflector radius. Taking advantage of the outer-space vacuum as a suitable environment for evaporative deposition of metal, a metal-evaporation source would be turned on and moved around the bubble to deposit a reflective metal film over the specified reflector area to a thickness of several microns. Then the source would be moved and aimed to deposit more metal around the edge of the reflector area, increasing the thickness there to approximately equal to 100 micron to form a frame. Then the bubble would be deflated and peeled off the metal, leaving a thin-film spherical mirror having an integral frame. The mirror would then be mounted for use. The feasibility of this technology has been proved by fabricating a prototype at JPL. As shown in the figure, a 2-in. (.5-cm) diameter hemispherical prototype reflector was made from a polymer bubble coated with silver, forming a very smooth surface.

Wang, Yu↗

Design and Measurements of Dual-Polarized Wideband Constant-Beamwidth Quadruple-Ridged Flared Horn

A quad-ridged, flared horn achieving nearly constant beamwidth and excellent return loss over a 6:1 frequency bandwidth is presented. Radiation pattern measurements show excellent beamwidth stability from 2 to 12 GHz. Measured return loss is > 10 dB over the entire band and > 15 dB from 2.5 to 11 GHz. Using a custom physical optics code, system performance of a radio telescope is computed and predicted performance is average 70% aperture efficiency and 10 Kelvin of antenna noise temperature.

decade bandwidth↗

NASA Tech Briefs, April 2012

Topics include: Computational Ghost Imaging for Remote Sensing; Digital Architecture for a Trace Gas Sensor Platform; Dispersed Fringe Sensing Analysis - DFSA; Indium Tin Oxide Resistor-Based Nitric Oxide Microsensors; Gas Composition Sensing Using Carbon Nanotube Arrays; Sensor for Boundary Shear Stress in Fluid Flow; Model-Based Method for Sensor Validation; Qualification of Engineering Camera for Long-Duration Deep Space Missions; Remotely Powered Reconfigurable Receiver for Extreme Environment Sensing Platforms; Bump Bonding Using Metal-Coated Carbon Nanotubes; In Situ Mosaic Brightness Correction; Simplex GPS and InSAR Inversion Software; Virtual Machine Language 2.1; Multi-Scale Three-Dimensional Variational Data Assimilation System for Coastal Ocean Prediction; Pandora Operation and Analysis Software; Fabrication of a Cryogenic Bias Filter for Ultrasensitive Focal Plane; Processing of Nanosensors Using a Sacrificial Template Approach; High-Temperature Shape Memory Polymers; Modular Flooring System; Non-Toxic, Low-Freezing, Drop-In Replacement Heat Transfer Fluids; Materials That Enhance Efficiency and Radiation Resistance of Solar Cells; Low-Cost, Rugged High-Vacuum System; Static Gas-Charging Plug; Floating Oil-Spill Containment Device; Stemless Ball Valve; Improving Balance Function Using Low Levels of Electrical Stimulation of the Balance Organs; Oxygen-Methane Thruster; Lunar Navigation Determination System - LaNDS; Launch Method for Kites in Low-Wind or No-Wind Conditions; Supercritical CO2 Cleaning System for Planetary Protection and Contamination Control Applications; Design and Performance of a Wideband Radio Telescope; Finite Element Models for Electron Beam Freeform Fabrication Process Autonomous Information Unit for Fine-Grain Data Access Control and Information Protection in a Net-Centric System; Vehicle Detection for RCTA/ANS (Autonomous Navigation System); Image Mapping and Visual Attention on the Sensory Ego-Sphere; HyDE Framework for Stochastic and Hybrid Model-Based Diagnosis; and IMAGESEER - IMAGEs for Education and Research.

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Implementation of a Digital Signal Processing Subsystem for a Long Wavelength Array Station

This paper describes the implementation of a Digital Signal Processing (DP) subsystem for a single Long Wavelength Array (LWA) station.12 The LWA is a radio telescope that will consist of many phased array stations. Each LWA station consists of 256 pairs of dipole-like antennas operating over the 10-88 MHz frequency range. The Digital Signal Processing subsystem digitizes up to 260 dual-polarization signals at 196 MHz from the LWA Analog Receiver, adjusts the delay and amplitude of each signal, and forms four independent beams. Coarse delay is implemented using a first-in-first-out buffer and fine delay is implemented using a finite impulse response filter. Amplitude adjustment and polarization corrections are implemented using a 2x2 matrix multiplication

Long Wavelength Array↗

Long-Term Multiwavelength Studies of High-Redshift Blazar 0836+710

Following gamma-ray flaring activity of high-redshift (z=2.218) blazar 0836+710 in 2011, we have assembled a long-term multiwavelength study of this object. Although this source is monitored regularly by radio telescopes and the Fermi Large Area Telescope, its coverage at other wavelengths is limited. The optical flux appears generally correlated with the gamma-ray flux, while little variability has been seen at X-ray energies. The gamma-ray/radio correlation is complex compared to some other blazars. As for many blazars, the largest variability is seen at gamma-ray wavelengths.

Thompson, D. J.↗

Hartebeesthoek Radio Astronomy Observatory (HartRAO)

HartRAO provides the only fiducial geodetic site in Africa, and it participates in global networks for VLBI, GNSS, SLR, and DORIS. This report provides an overview of geodetic VLBI activities at HartRAO during 2012, including the conversion of a 15-m alt-az radio telescope to an operational geodetic VLBI antenna.

Nickola, Marisa↗

Instituto Geografico Nacional of Spain

This report updates the description of the space geodesy facilities of the Spanish National Geographic Institute (IGN). The current 40-meter radio telescope at Yebes, a network station for IVS, has performed geodetic VLBI observations regularly since September 2008. In addition to this, the project to establish an Atlantic Network of Geodynamical and Space Stations (RAEGE) is progressing with the construction of the first antenna, which is being erected at Yebes.

Colomer, Francisco↗

Results from Testing Crew-Controlled Surface Telerobotics on the International Space Station

During Summer 2013, the Intelligent Robotics Group at NASA Ames Research Center conducted a series of tests to examine how astronauts in the International Space Station (ISS) can remotely operate a planetary rover. The tests simulated portions of a proposed lunar mission, in which an astronaut in lunar orbit would remotely operate a planetary rover to deploy a radio telescope on the lunar far side. Over the course of Expedition 36, three ISS astronauts remotely operated the NASA "K10" planetary rover in an analogue lunar terrain located at the NASA Ames Research Center in California. The astronauts used a "Space Station Computer" (crew laptop), a combination of supervisory control (command sequencing) and manual control (discrete commanding), and Ku-band data communications to command and monitor K10 for 11 hours. In this paper, we present and analyze test results, summarize user feedback, and describe directions for future research.

robotics↗

Lunar Brightness Variations with Phase at 4.3-MM Wave Length

The lunar radio observations and interpretations of Piddington and Minnett (1949) and Gibson (1958) show that the lunar brightness variation with phase at millimeter wave lengths can be used to determine the physical properties of the lunar surface. They found that the millimeter-wave brightness lagged the optical phase, and their interpretation was that the millimeter radiation originates below a surface layer that is a very good thermal insulator. The thickness of this layer could not be determined from observations at one frequency. Observations at different frequencies give different results because of the wave-length dependence of the radio absorption by the surface material. The attenuation in the material increases with decreasing wave length, and therefore it is possible, in principle, to determine surface layer thickness from radio observations at several wave lengths. For this reason, observations of lunar radiation were started at the Naval Research Laboratory at a wave length of 4.3 mm. This is half the wave length used by Gibson (1958) in his earlier studies. The radio telescope used for these observations has been described in detail in a previous publication (Coates 1958). The antenna is a parabolic reflector 10 feet in diameter, and it has a beam width of 6.7 minutes of arc at the wave length of 4.3 mm. This is about one-fifth the diameter of the moon. The receiver was a Dicke-type radiometer.

Coates, Robert J.↗

Surface Telerobotics: Development and Testing of a Crew Controlled Planetary Rover System

During Summer 2013, we conducted a series of tests to examine how astronauts in the In- ternational Space Station (ISS) can remotely operate a planetary rover. The tests simulated portions of a proposed mission, in which an astronaut in lunar orbit remotely operates a planetary rover to deploy a radio telescope on the lunar farside. In this paper, we present the design, implementation, and preliminary test results.

Fong, Terry↗

Robotic Technology Development at Ames: The Intelligent Robotics Group and Surface Telerobotics

Future human missions to the Moon, Mars, and other destinations offer many new opportunities for exploration. But, astronaut time will always be limited and some work will not be feasible for humans to do manually. Robots, however, can complement human explorers, performing work autonomously or under remote supervision from Earth. Since 2004, the Intelligent Robotics Group has been working to make human-robot interaction efficient and effective for space exploration. A central focus of our research has been to develop and field test robots that benefit human exploration. Our approach is inspired by lessons learned from the Mars Exploration Rovers, as well as human spaceflight programs, including Apollo, the Space Shuttle, and the International Space Station. We conduct applied research in computer vision, geospatial data systems, human-robot interaction, planetary mapping and robot software. In planning for future exploration missions, architecture and study teams have made numerous assumptions about how crew can be telepresent on a planetary surface by remotely operating surface robots from space (i.e. from a flight vehicle or deep space habitat). These assumptions include estimates of technology maturity, existing technology gaps, and likely operational and functional risks. These assumptions, however, are not grounded by actual experimental data. Moreover, no crew-controlled surface telerobotic system has yet been fully tested, or rigorously validated, through flight testing. During Summer 2013, we conducted a series of tests to examine how astronauts in the International Space Station (ISS) can remotely operate a planetary rover across short time delays. The tests simulated portions of a proposed human-robotic Lunar Waypoint mission, in which astronauts in lunar orbit remotely operate a planetary rover on the lunar Farside to deploy a radio telescope array. We used these tests to obtain baseline-engineering data.

robotics↗

Relay Communications Support to the ExoMars Schiaparelli Lander

The European Space Agency’s ExoMars Trace Gas Orbiter (TGO) arrived at Mars on October 19, 2016, three days after releasing the Schiaparelli Lander on a ballistic trajectory to Meridiani Planum. During the separation event, and subsequently during Schiaparelli’s Entry, Descent, and Landing (EDL), the NASA-provided Electra UHF payload onboard TGO was used to record signals from the Schiaparelli Lander for post-processing on the ground to recover both tracking of the lander’s carrier signal and reconstruction of the lander’s 8 kb/s telemetry. In addition, ESA’s Mars Express orbiter also recorded the Schiaparelli signal, with ground post-processing providing independent tracking of the lander carrier signal, and the Giant Metrewave Radio Telescope near Pune, India was configured to provide real-time detection of the lander carrier signal. While an anomaly in the latter stages of EDL led to loss of the lander, these critical event data sets, and in particular the telemetry reconstruction enabled by the TGO Electra recording, proved essential in enabling detailed diagnosis of the anomaly. And while the loss of the lander during EDL precluded the planned surface relay operations, the preparations for that activity provide important lessons learned for future Mars relay support scenarios.

Edwards, Charles D., Jr.↗

Using Big Data Technologies with Earth Science Data in HDF5: HDF5 Scalable Solutions

HDF5 (Hierarchical Data Format 5) is open-source, high-performance software that consists of an abstract data model, library, and fileformat used for storing and managing extremely large and/or complex data collections. NASA Earth Observing System (EOS) Data and Information Systems use HDF5 as an archival format to store remote sensing data from EOS satellites. HDF5 is also used to store other types of Geoscience and Strophysical data, e.g., seismic data and data from Low-Frequency Array (LOFAR) radio telescopes. Data stored in HDF5 has reached tens of petabytes and is growing at an accelerated rate.With the growing amout of HDF5 Earth Science data to analyze and process, scientists need to adopt big data technologies including new storage paradigms such as cloud and object storage. To run models and perform data analysis they also need to utilizied efficient and diverse ways to access data, from high-performance computing's (HPC) Message Passing Interface (MPI) I/O and deep memory hierarchies (DMH) to non-HPC frameworks such as Apache Hadoop, Spark, and Drill. The HDF Group continually works to enable usage of big data technologies in HDF software.

Knox, Larry↗

Improving the S/X Celestial Reference Frame in the South

We believe that the S/X celestial reference frame(CRF) can be improved in the far-south by a factor of 2 in density and a factor of 2.5 in precision. We have started a collaboration to meet these goals. We have increased the data rates on existing IV Sastrometric sessions in the south from 256 Mbps to 1 Gbps. We will use this sensitivity to detect weaker sources and to improve the precision of sources in the southern S/X CRF, while simultaneously increasing the number of sources, in particular the overlap with other frames such as K-and Ka-band in the radio and the Gaia frame in the optical. VLBI observations in the southern celestial hemisphere have always been more difficult both because there are fewer radio telescopes in the south than in the north, and because there are fewer known reference sources in the south. There have been many efforts in recent years to increase the number of known reference sources in the south, in particular the LBA calibrator Survey (LCS), which has already produced a significant improvement at X-band. The ICRF-3 is expected to make significant improvements in the south, however the south has not yet reached parity with the north and much work remains to be done. Therefore dedicated astrometric and imaging observations have already begun to improve the southern CRF at S/Xbands.

Basu, Sayan↗