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At least 1,009 records · Page 56
All sourcesNASA NTRSDOE OSTI
NASA NTRS2003

Development of a safe ground to space laser propagation system for the optical communications telescope laboratory

Furthering pursuits in high bandwidth communications to future NASA deep space and neat-Earth probes, the Jet Propulsion Laboratory (JPL) is building the Optical communications Telescope Laboratory (OCTL) atop Table Mountain in Southern California. This R&D optical antenna will be used to develop optical communication strategies for future optical ground stations. Initial experiments to be conducted include propagating high-powered, Q-switched laser beams to retro-reflecting satellites. Yet laser beam propagation from the ground to space is under the cognizance of various government agencies, namely: the Occupational Safety and Health Administration (ISHA) that is responsible for protecting workforce personnel; the Federal Aviation Administration (FAA) responsible for protecting pilots and aircraft; and the Laser Clearinghouse of Space Command responsible for protecting space assets. To ensure that laser beam propagation from the OCTL and future autonomously operated ground stations comply with the guidelines of these organizations, JPL is developing a multi-tiered safety system that will meet the coordination, monitoring, and reporting functions required by the agencies. At Tier 0, laser operators will meet OSHA safety standards for protection and access to the high power lasers area will be restricted and interlocked. Tier 1, the area defined from the telescope dome out to a range of 3.4-km, will utilize long wave infrared camera sensors to alert operators of at risk aircraft in the FAA controlled airspace. Tier 2, defined to extend from 3.4-km out to the aircraft service ceiling in FAA airspace, will detect at risk aircraft by radar. Lastly, beam propagation into space, defined as Tier 3, will require coordination with the Laser Clearinghouse. A detailed description of the four tiers is presented along with the design of the integrated monitoring and beam transmission control system.

laser safety↗
NASA NTRS2006

Till the Ductile Anchor Hold: Towards Space Settlements in the 21st Century.

Humans are restless explorers. For 99% of humanity s time on Earth, we have been nomadic wanderers, not farmers, warriors, factory workers, developers, or NASA employees. Only recently--for only a few thousand years--have most humans been tied to the land as many are now. But as more and more of us live in information societies and some indeed in dream societies where our identity derives from the knowledge we share and the image we project, and not from the property we own or the manual work we do, the time may be coming when we should break free from the land, and roam once again. But beware: the reality of Man and Woman the Explorer has a very dark side as well. Many people where I live view the recent experience of Man on the Move as a history of theft, murder, racism, exploitation, and genocide. So we need to be very careful if we say that space exploration is only natural for humans, since the experience has not been very uplifting and noble for most recipients of the exploring of others. But such warnings are not new. Humans have been alerting each other to the dangers of change and novelty from the very beginning: Who and what is this?

Dator, Jim↗
NASA NTRS2006

Sensor Management for Applied Research Technologies (SMART)-On Demand Modeling (ODM) Project

NASA requires timely on-demand data and analysis capabilities to enable practical benefits of Earth science observations. However, a significant challenge exists in accessing and integrating data from multiple sensors or platforms to address Earth science problems because of the large data volumes, varying sensor scan characteristics, unique orbital coverage, and the steep learning curve associated with each sensor and data type. The development of sensor web capabilities to autonomously process these data streams (whether real-time or archived) provides an opportunity to overcome these obstacles and facilitate the integration and synthesis of Earth science data and weather model output. A three year project, entitled Sensor Management for Applied Research Technologies (SMART) - On Demand Modeling (ODM), will develop and demonstrate the readiness of Open Geospatial Consortium (OGC) Sensor Web Enablement (SWE) capabilities that integrate both Earth observations and forecast model output into new data acquisition and assimilation strategies. The advancement of SWE-enabled systems (i.e., use of SensorML, sensor planning services - SPS, sensor observation services - SOS, sensor alert services - SAS and common observation model protocols) will have practical and efficient uses in the Earth science community for enhanced data set generation, real-time data assimilation with operational applications, and for autonomous sensor tasking for unique data collection.

Goodman, M.↗
NASA NTRS2006

The Swift-BAT Hard X-ray Transient Monitor

The Burst Alert Telescope (BAT) on the Swift satellite is a large field of view instrument that continually monitors the sky to provide the gamma-ray burst trigger for Swift. An average of more than 70% of the sky is observed on a daily basis. The survey mode data is processed on two sets on time scales: from one minute to one day as part of the transient monitor program, and from one spacecraft pointing (approx.20 minutes) to the full mission duration for the hard X-ray survey program. The transient monitor has recently become public through the web site http:// swift.gsfc.nasa.gov/docs/swift/results/transients/. Sky images are processed to detect astrophysical sources in the 15-50 keV energy band and the detected flux or upper limit is calculated for >100 sources on time scales up to one day. Light curves are updated each time that new BAT data becomes available (approx.10 times daily). In addition, the monitor is sensitive to an outburst from a new or unknown source. Sensitivity as a function of time scale for catalog and unknown sources will be presented. The daily exposure for a typical source is approx.1500-3000 seconds, with a 1-sigma sensitivity of approx.4 mCrab. 90% of the sources are sampled at least every 16 days, but many sources are sampled daily. It is expected that the Swift-BAT transient monitor will become an important resource for the high energy astrophysics community.

Krimm, Hans↗
NASA NTRS2006

Gamma-ray Observations with Swift and their Impact on the TeV Community

The Swift gamma-ray burst explorer was launched on Nov. 20, 2004 from Cape Canaveral, Florida. The first instrument onboard became fully operational less than a month later. Since that time the Burst Alert Telescope (BAT) on Swift has detected more than 150 gamma-ray bursts (GRBs), most of which have also been observed within two minutes by the Swift narrow-field instruments: the X-Ray Telescope (XRT) and the Ultra-Violet and Optical Telescope (UVOT). Swift trigger notices are distributed worldwide within seconds of the trigger through the Gamma-ray burst Coordinates Network (GCN) and a substantial fraction of GRBs have been followed up by ground and space-based telescopes, ranging in wavelength from radio to TeV. Results have included the first rapid localization of a short GRB and further validation of the theory that short and long bursts have different origins; detailed observations of the power-law decay of burst afterglows leading to an improved understanding of the fireball and afterglow models; and detection of the most distant GRB ever found. Swift is also a sensitive X-ray observatory with capabilities to monitor galactic and extragalactic transients on a daily basis, carry out the first all-sky hard X-ray survey since HEAO-1, and study in detail the spectra of X-ray transients. The talk will emphasize the connection between Swift/BAT GRB observations and source monitoring and TeV observations.

Krimm, Hans↗
NASA NTRS2007

Swift/BAT and RXTE Observations of the Peculiar X-ray Binary 4U 2206+54 - Disappearance of the 9.6 Day Modulation

Observations of the high-mass X-ray binary 4U 2206+54 with the Swift Burst Alert Telescope (BAT) do not show modulation at the previously reported period of 9.6 days found from observations made with the Rossi X-ray Timing Explorer (RXTE) All-Sky Monitor (ASM). Instead, the strongest peak in the power spectrum of the BAT light curve occurs at a period of 19.25+/-0.08 days, twice the period found with the RXTE ASM. The maximum of the folded BAT light curve is also delayed compared to the maximum of the folded ASM light curve. The most recent ASM data folded on twice the 9.6 day period show 'similar morphology to the folded BAT light curve. This suggests that the apparent period doubling is a recent secular change rather than an energy-dependent effect. The 9.6 day period is thus not a permanent strong feature of the light curve. We suggest that the orbital period of 4U 2206+54 may be twice the previously proposed value.

Corbet, R. H. D.↗
NASA NTRS1978

Intruder Detector

The shadowy prowler is attempting a break-in, unaware that his presence has already been detected and reported by the device in the lower left corner of the photo. It is part of a three-element ntruder Detecti on System developed by NASA's Ames Research Center from technology acquired in the Apollo lunar exploration program. Apollo astronauts left behind on the moon small portable seismic (shock) detectors to record subsurface vibrations and transmit to Earth data on the moon's density and thickness. A similar seismic detector is the key component of the lntruder Detection System. Encased in a stainless steel tube, the detector is implanted in the ground outside the facility being protected-home, bank, industrial or other facilities. The vibration-sensing detector picks up the footstep of anyone within a preset range. The detector is connected by cable to the transmitter, which relays the warning to a portable radio receiver. The radio alerts plant guards or home occupants by emitting an audible tone burst for each footstep.

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NASA NTRS2006

Feeling Well Rested and Wide Awake When it Counts

Responding to a congressional concern about aviation safety, NASA's Ames Research Center created the Ames Fatigue/Jet Lag Program in 1980 to examine the extent to which fatigue, sleep loss, and circadian disruption affect pilot performance. The program s primary research was conducted in field settings, as well as in a variety of aviation, controlled laboratory, and full-mission flight-simulation environments, to study fatigue factors and circadian disruption in short-haul, long-haul, military, cargo, and helicopter operations. In 1990, NASA changed the program s name to the Fatigue Countermeasures Group, to provide a greater emphasis on the development and evaluation of countermeasures that would mitigate the adverse effects of fatigue and maximize flight crew performance and alertness. The research conducted by this group at Ames included field studies of cockpit rest, quantity and quality of onboard sleep, and performance changes associated with long-haul flights.

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NASA NTRS1979

Smoke Detector

In the photo, Fire Chief Jay Stout of Safety Harbor, Florida, is explaining to young Richard Davis the workings of the Honeywell smoke and fire detector which probably saved Richard's life and that of his teen-age brother. Alerted by the detector's warning, the pair were able to escape their burning home. The detector in the Davis home was one of 1,500 installed in Safety Harbor residences in a cooperative program conducted by the city and Honeywell Inc.

Source record↗
NASA NTRS2007

The Swift Gamma-ray Burst Explorer: Early Views into Black-hole Creation

This viewgraph presentation reviews the discovery of Gamma-ray Bursts (GRBs) in the 1960's and early 1970's, and the characteristics of GRBs. Theoretical predictions and explanations are reviewed. The first observation of a GRB by the Beppo-SAX is discussed, and then the need develop a Gamma Ray Burst detector with a larger field of view, that has rapid follow-up capabilities and has the ability to rapidly get localized positions to the ground. The Swift instruments (i.e., the Burst Alert Telescope (BAT), the X-Ray Telescope (XRT) and the UV/Optical Telescope (UVOT)) are shown and described. The scenario for observing of GRBs is reviewed. Many charts of the some of the GRBs data and GRB spectra are shown.

Hill, Joe↗
NASA NTRS2007

Real-time Affective Indices of Potential CRM Breakdown: Qualitative Testing of an Operational Hypothesis

This viewgraph presentation begins by showing several cases where poor crew resource management (CRM) resulted in aircraft accidents. The presenter reviews the emotional states that are present in a situation that frequently leads to an accident. The operational answer suggested is given as an acronym: PACE, which stand for Probe, Alert, Challenge, Emergency Action.

Dickerson, Mark↗
NASA NTRS2007

Evidence of the Exponential Decay Emission in the Swift Gamma-ray Bursts

We present a systematic study of the steep decay emission of gamma-ray bursts (GRBs) observed by the Swift X-Ray Telescope (XRT). In contrast to the analysis in recent literature, instead of extrapolating the data of Burst Alert Telescope (BAT) down into the XRT energy range, we extrapolated the XRT data up to the BAT energy range, 15-25 keV, to produce the BAT and XRT composite light curve. Based on our composite light curve fitting, we have confirmed the existence of an exponential decay component which smoothly connects the BAT prompt data to the XRT steep decay for several GRBs. We also find that the XRT steep decay for some of the bursts can be well fitted by a combination of a power-law with an exponential decay model. We discuss that this exponential component may be the emission from an external shock and a sign of the deceleration of the outflow during the prompt phase.

Sakamoto, T.↗
NASA NTRS2005

Operational Aspects of Space Radiation Analysis

Minimizing astronaut's short and long-term medical risks arising from exposure to ionizing radiation during space missions is a major concern for NASA's manned spaceflight program, particularly exploration missions. For ethical and legal reasons, NASA follows the "as low as reasonably achievable" (ALARA) principal in managing astronaut's radiation exposures. One implementation of ALARA is the response to space weather events. Of particular concern are energetic solar particle events, and in low Earth orbit (LEO), electron belt enhancements. To properly respond to these events, NASA's Space Radiation Analysis Group (SRAG), in partnership with the NOAA Space Environment Center (SEC), provides continuous flight support during U.S. manned missions. In this partnership, SEC compiles space weather data from numerous ground and space based assets and makes it available in near real-time to SRAG (along with alerts and forecasts), who in turn uses these data as input to models to calculate estimates of the resulting exposure to astronauts. These calculations and vehicle instrument data form the basis for real-time recommendations to flight management. It is also important to implement ALARA during the design phase. In order to appropriately weigh the risks associated with various shielding and vehicle configuration concepts, the expected environment must be adequately characterized for nominal and worst case scenarios for that portion of the solar cycle and point in space. Even with the best shielding concepts and materials in place (unlikely), there will be numerous occasions where the crew is at greater risk due to being in a lower shielded environment (short term transit or lower shielded vehicles, EVAs), so that accurate space weather forecasts and nowcasts, of particles at the relevant energies, will be crucial to protecting crew health and safety.

Weyland, M. D.↗
NASA NTRS2007

DTED Integrity Monitoring Using Differential GPS and Radar Altimeter

This paper discusses a real-time digital terrain elevation data (DTED) integrity monitor for Civil Aviation applications. Providing pilots with Synthetic Vision (SV) displays containing terrain information has the potential to improve flight safety by improving situational awareness and thereby reducing the likelihood of Controlled Flight Into Terrain (CFIT). Utilization of the DTED for flight-critical terrain-displays, however, requires a DTED integrity check and timely integrity alerts to the pilots in those cases where DTED may provide hazardous misleading information. The discussed integrity monitor checks the consistency between the sensed terrain profile as computed from DGPS and radar altimeter data and the terrain profile as given by the DTED. Probability of agreement between these two profiles is used to monitor the DTED integrity. A case study to verify the integrity monitor#s performance is presented based on data collected during flight testing performed by NASA at Asheville, NC.

Young, Steve↗
NASA NTRS2006

NASA Critical Facilities Maintenance Assessment

Critical Facilities Maintenance Assessment (CFMA) was first implemented by NASA following the March 2000 overtest of the High Energy Solar Spectroscopic Imager (HESSI) spacecraft. A sine burst dynamic test using a 40 year old shaker failed. Mechanical binding/slippage of the slip table imparted 10 times the planned force to the test article. There was major structural damage to HESSI. The mechanical "health" of the shaker had not been assessed and tracked to assure the test equipment was in good working order. Similar incidents have occurred at NASA facilities due to inadequate maintenance (e.g., rainwater from a leaky roof contaminated an assembly facility that housed a spacecraft). The HESSI incident alerted NASA to the urgent need to identify inadequacies in ground facility readiness and maintenance practices. The consequences of failures of ground facilities that service these NASA systems are severe due to the high unit value of NASA products.

maintenance↗
NASA NTRS2006

Using Satellite Data to Characterize the Temporal Thermal Behavior of an Active Volcano: Mount St. Helens, WA

ASTER thermal infrared data over Mt. St Helens were used to characterize its thermal behavior from Jun 2000 to Feb 2006. Prior to the Oct 2004 eruption, the average crater temperature varied seasonally between -12 and 6 C. After the eruption, maximum single-pixel temperature increased from 10 C (Oct 2004) to 96 C (Aug 2005), then showed a decrease to Feb 2006. The initial increase in temperature was correlated with dome morphology and growth rate and the subsequent decrease was interpreted to relate to both seasonal trends and a decreased growth rate/increased cooling rate, possibly suggesting a significant change in the volcanic system. A single-pixel ASTER thermal anomaly first appeared on Oct 1, 2004, eleven hours after the first eruption - 10 days before new lava was exposed at the surface. By contrast, an automated algorithm for detecting thermal anomalies in MODIS data did not trigger an alert until Dec 18. However, a single-pixel thermal anomaly first appeared in MODIS channel 23 (4 um) on Oct 13, 12 days after the first eruption - 2 days after lava was exposed. The earlier thermal anomaly detected with ASTER data is attributed to the higher spatial resolution (90 m) compared with MODIS (1 m) and the earlier visual observation of anomalous pixels compared to the automated detection method suggests that local spatial statistics and background radiance data could improve automated detection methods.

Advanced Spaceborne Thermal Emission and Reflectio↗
NASA NTRS2007

A Comparison of the Variability of the Symbiotic X-ray Binaries GX 1+4, 4U 1954+31, and 4U 1700+24 from Swift/BAT and RXTE/ASM Observations

We present an analysis of the X-ray variability of three symbiotic X-ray binaries, GX 1+4, 4U 1700+24, and 4U 1954+31, using observations made with the Swift Burst Alert Telescope (BAT) and the Rossi X-ray Timing Explorer (RXTE) All-Sky Monitor (ASM). Observations of 4U 1954+31 with the Swift BAT show modulation at a period near 5 hours. Models to explain this modulation are discussed including the presence of an exceptionally slow X-ray pulsar in the system and accretion instabilities. We conclude that the most likely interpretation is that 4U 1954+31 contains one of the slowest known X-ray pulsars. Unlike 4U 1954+31, neither GX 1+4 nor 4U 1700+24 show any evidence for modulation on a timescale of hours. An analysis of the RXTE ASM light curves of GX l+4, 4U 1700+24, and 4U 1954+31 does not show the presence of periodic modulation in any source, although there is considerable variability on long timescales for all three sources. There is no modulation in GX 1+4 on either the optical 1161 day orbital period or a previously reported 304 day X-ray period. For 4U 1700+24 we do not confirm the 404 day period previously proposed for this source from a shorter duration ASM light curve.

Corbet, R. H. D.↗
NASA NTRS2007

Chemical-Sensing Cables Detect Potential Threats

Intelligent Optical Systems Inc. (IOS) completed Phase I and II Small Business Innovation Research (SBIR) contracts with NASA's Langley Research Center to develop moisture- and pH-sensitive sensors to detect corrosion or pre-corrosive conditions, warning of potentially dangerous conditions before significant structural damage occurs. This new type of sensor uses a specially manufactured optical fiber whose entire length is chemically sensitive, changing color in response to contact with its target, and demonstrated to detect potentially corrosive moisture incursions to within 2 cm. After completing the work with NASA, the company received a Defense Advanced Research Projects Agency (DARPA) Phase III SBIR to develop the sensors further for detecting chemical warfare agents, for which they proved just as successful. The company then worked with the U.S. Department of Defense (DoD) to fine tune the sensors for detecting potential threats, such as toxic industrial compounds and nerve agents. In addition to the work with government agencies, Intelligent Optical Systems has sold the chemically sensitive fiber optic cables to major automotive and aerospace companies, who are finding a variety of uses for the devices. Marketed under the brand name Distributed Intrinsic Chemical Agent Sensing and Transmission (DICAST), these unique continuous-cable fiber optic chemical sensors can serve in a variety of applications: Corrosive-condition monitoring, aiding experimentation with nontraditional power sources, as an economical means of detecting chemical release in large facilities, as an inexpensive "alarm" systems to alert the user to a change in the chemical environment anywhere along the cable, or in distance-resolved optical time domain reflectometry systems to provide detailed profiles of chemical concentration versus length.

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