Search NASA⌕ Search

SEARCH · Search NASA

Results for “SUNSET”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1994

Ionoshperic effects of the March 1990 magnetic storm: Comparison of theory and measurement

This paper presents a comparison of the measured and modeled ionospheric response to magnetic storms at Millstone Hill and Arecibo during March 16-23, 1990. Magnetic activity was low until midday Universal Time (UT) on day 18 when Kp reached 6, days 19 and 20 were quiet, but a large storm occurred around midnight UT on day 20 (Kp=7) ad it was a moderately disturbed (Kp=4) for the remainder of the study period. At Millstone Hill, the daytime peak density (Nm F2) showed only a modest 30% decrease in response to the first storm and recovered to prestorm values before the onset of the second storm. The model reproduces the daytime peak electron density well for this period. However, the severe storm on March 20 caused a factor of 4 deplection in electron density, while the model densities were not greatly affected. the inclusion of vibrationally excited nitrogen N2(sup *) in the model was unable to account for the observed large electron density depletions afterward March 20. The storm did not appear to affect the overall magnitude of the electron density at Arecibo very much, but did cause unusual wavelike structure in the peak density and peak height following the storm. The model reproduces the daytime Nm F2 very well for Arecibo, but after sunset the model densities decay too rapidly. This study indicates that successful modeling of severe ionospheric stroms will require better definition of the storm time inputs, especially of the neutral atmosphere.

Richards, P. G.↗
NASA NTRS1995

Satellite observations of zonal electric fields near sunrise in the equatorial ionosphere

We report here on a number of examples of anomalous enhancements of eastward electric fields near sunrise in the equatorial ionospheric F-region. These examples were selected from the data base of the equatorial satellite, San Marco D (1988), which measured ionospheric electric fields during a period of solar minimum. The eastward electric fields reported correspond to vertical plasma drifts. The examples studied here are similar in signature and polarity to the pre-reversal electric field enhancements seen near sunset from ground-based radar systems. The morphology of these sunrise events, which are observed on about 14% of the morning-side satellite passes, are studied as a function of local zonal velocity, magnetic activity, geographic longitude and altitude. The nine events studied occur at locations where the zonal plasma flow is generally measured to be eastward, but reducing as a function of local time and at satellite longitudes where the magnetic declination has the opposite polarity as the declination of the sunrise terminator.

Aggson, T. L.↗
NASA NTRS1993

Diffusion of Na and K in the uppermost regolith of Mercury

We examine the conditions under which ions impacting the Hermean surface can act as a regional source of enhanced atmospheric column through ion implantation and subsequent release at the surface. At most latitudes, energetic (a few keV) Na or K ions which impact the nightside surface, are released quickly (well before noon) upon warming of the surface. We show that the relative sunrise/sunset difference produced by ion implantation is ((n)(sub SR) - (n)(sub SS)/(n)(sub Ave) = f, where f is the fraction of the photo-ions recycled, (n)(sub SR) is the average zenith column above the sunrise portion of the illuminated hemisphere, (n)(sub SS) is the average zenith column in the sunset portion, and (n)(sub Ave) is the average column over the sunlit disk. Thus, to produce a large sunrise/sunset difference via ion implantation and subsequent release requires efficient (close to total) recycling. We show that the most extensive set of available data reduced to Na column abundance does not show any sunrise enhancement. We argue that the K data do not permit an unambiguous interpretation in favor of sunrise/sunset differences. We further find that if an efficient surface loss process for the alkali is not operating after sunrise, the initial Na and K distribution will relax into the bulk of the solid. Preserved abundance gradients of Na and K in lunar glasses that the Arrhenius coefficients for impact glasses are likely more modest than those for laboratory glasses derived from rock by nonimpact processes, but the effect of the more modest diffusion rates is only to delay the efficient loss of Na by a few Earth days. We argue that implantation can lead to observable regional increases in the observed Na or K column densities only if it occurs at very high latitudes, where diffusion is slow. It is typically lower energy ions which impact at high latitude and these are both more numerous than the high energy ions and possess smaller average penetration depths; thus there are additional reasons to favor a high-latitude locus for any possible prompt return related increases in zenith column. We find that we cannot rule out sputtering as a source process, as the low-energy ions are efficient sputterers. Finally, we argue that the observed Na/K ratio in the atmopshere may be the expression of their different asymptotic rates of loss from the interiors of the regolith grains. If so, this allows us to fix the importance of sputtering and photon stimulated desorption relative to impact vaporization.

Killen, R. M.↗
NASA NTRS1993

Upper Atmosphere Research Satellite attitude disturbances during shadow entry and exit

The Upper Atmosphere Research Satellite (UARS), as with the Landsat-4 and Landsat-5 spacecraft, experiences large attitude disturbances when entering and exiting the Earth's shadow. Previous investigations have provided some evidence linking these disturbances to rapid bending of the solar array but have also raised questions. For example, the magnitudes of the roll attitude disturbances have shown an unmolested asymmetry, and the timing of the disturbances at sunrise appears to disagree with the modeled timing. A better understanding of this phenomenon is important in assessing the implications for UARS science gathering and for future mission design analysis. To this end, UARS attitude, sensor, and actuator data are used to evaluate the disturbances as they vary with solar beta angle and solar array drive angle. The attitude data are examined during specific periods of interest, such as the month in which the solar array was parked in its high-noon position, and are also tracked from the beginning of the mission to determine any trends that may result from changing mass properties due to cryogen boiloff and propellant usage. Attitude rate and torque profiles are derived from inertial reference until data and related to the disturbances seen in the attitude data. The timing of the disturbances with respect to spacecraft sunset and sunrise is characterized to allow event predictions. Stability during the disturbances is discussed in terms of science instrument requirements. Finally, the results are compared with the behavior predicted by models that are based on solar array bending.

Lambertson, M.↗
NASA NTRS1991

[STS-48 Mission Highlights Resource Tape. Part 1 of 2]

In this first part of a two part video mission-highlights set, the flight of the STS-48 Space Shuttle Orbiter Discovery is reviewed. The flight crew consisted of: J. O. Creighton (Commander); Ken Reightler (Pilot); Charles 'Sam' Gemar (Mission Specialist); James 'Jim' Buchli (MS); and Mark Brown (MS). Step-by-step pre-launch and sunset launch sequences are shown with accompanying shots inside the Mission Control Center. The primary goal of this mission was the deployment of Upper Atmosphere Research Satellite (UARS). Other (secondary) payloads included: the MidDeck Zero Gravity Experiment (MODE); the Sam/Cream device; the Shuttle Activation Monitor/Cosmic Ray Effects and Activation Monitor Experiment; and the Physiology and Anatomical Rodent Experiment (PARE). Crew activities were shown, along with Earth views (Aurora Borealis (B/W), light from the Kuwait oil fires, lightning over Italy and other areas, polar regions and ice caps, and the United States at night (B/W)). This was the thirteenth flight of the Space Shuttle Discovery. A night landing is shown.

Source record↗
NASA NTRS1995

STS-69 Postflight Presentation

A postflight conference of the STS-69 mission is presented. The flightcrew ('The Dog Team') consisted of Cmdr. David Walker, Pilot Kenneth Cockrell, Payload Cmdr. James Voss, and Mission Specialists James Newman and Michael Gernhardt. The mission's primary objective was the deployment and retrieval of the SPARTAN-201 satellite, which investigated the interaction between the Sun and it's solar wind. Other secondary experiments and shuttle payloads included the Wake Shield Facility (WSF), which grew several layers of semiconductor films, the International Extreme Ultraviolet Hitchhiker (IEH-1), the Capillary Pumped Loop-2/Gas Bridge Assembly (CAPL-2/GBA), several Get Away Specials (GAS) experiments, the Electrolysis Performance Improvement Concept Study (EPICS), the Thermal Energy Storage (TES-2) experiment, the Commercial Generic Bioprocessing Apparatus-7 (CGBA-7), the National Institutes of Health-Cells 4 (NIH-C4) experiment, and the Biological Research in Canister-6 (BRIC-6) experiment. Earth views consisted of Saudi Arabia water wells, uncommon vortices over Oman, the Amazon River, the Bahamas, Somalia, a sunset over the Earth's horizon, and two hurricanes, Luis and Marilyn.

Source record↗
NASA NTRS1995

Lidar measurements at Lauder, NZ

In March of 1994, the GSFC Stratospheric Ozone Lidar was deployed to the Network for the Detection of Stratospheric Change (NDSC) site at Lauder, NZ. This was in conjunction with a series of NASA ER-2 flights from Christchurch, NZ south to the Antarctic Circle. These flights were organized to study the chemistry of the stratosphere before, during and after the formation of the well-known 'ozone hole'. Lidar measurements were made at four different time periods corresponding to the times of the ER-2 flights. Lauder is situated nearly along the flight path as the aircraft flew south and so the lidar measurements provide a checkpoint for the ozone, aerosol and temperature instruments onboard the aircraft. Whenever the weather permitted, lidar measurements were made as near to dawn, prior to the flight, and as near to sunset, after the flight. This provided data as close to the aircraft transit time as possible. More than 70 individual lidar measurements were made, each consisting of a vertical profile of ozone, temperature, and aerosol. These were made over three different seasons and show seasonal variation. Of particular interest in the lidar data base is the wintertime stratospheric - mesospheric temperature profiles, which show large variations at the stratopause and also some significant wave activity.

McGee, Thomas J.↗
NASA NTRS1996

STS-75 Flight Day 9

On this ninth day of the STS-75 mission, the flight crew, Cmdr. Andrew Allen, Pilot Scott Horowitz, Payload Cmdr. Franklin Chang-Diaz, Payload Specialist Umberto Guidoni (Italy), and Mission Specialists Jeffrey Hoffman, Maurizio Cheli (ESA) and Claude Nicollier (ESA), are shown tracking the free-orbiting tethered satellite and performing various experiments from the United States Microgravity Payload-3 (USMP-3). An in-orbit interview with Allen, Cheli, and Guidoni by the Italian news media is shown. The astronauts answer a variety of questions concerning the loss of the tethered satellite, and the progress of the other mission experiments. Earth views include a sunset and horizon shots.

Source record↗
NASA NTRS1995

STS-74 Post Flight Presentation

The flight crew of the STS-74 Space Shuttle Orbiter Atlantis (Cmdr. Ken Cameron, Pilot Jim Halsell, and Mission Specialists Chris Hadfield, Jerry Ross, and William McArthur) present an overview of their flight mission, whose primary objective was the rendezvous and space docking with the Russian Mir Space Station. Video film footage includes: prelaunch and launch activities; shuttle launch; installation of the Russian-made docking module to the orbiter; in-orbit rendezvous; in-orbit docking between Mir and the orbiter; general crew activities; transfer of supplies, equipment, and a crystal growth experiment to Mir; data collection of Mir thruster firings; undocking maneuvers and Mir fly around; pre-return checkout of flight systems; and reentry and landing of the orbiter. Earth views include horizon sunsets, atmospheric boundary layers, and a variety of geographical location footage (New Orleans; Atlanta; James Bay, Canada; Poland; Turkey; Mt. Pinatubo, Philippines; Salt Lake City, Utah; and Colorado).

Source record↗
NASA NTRS1995

Shuttle Earth Views, 1994

In this fourth part of a four-part video compilation of Space Shuttle Earth views, various geographical areas are shown, including both land and water masses. The views covered the Middle East (Saudi Arabia, Sinai, Jordan , Egypt, Iran, Iraq, Kuwait, Bahrain, Qatar, and the United Arab Emirates), northeastern Africa (Yemen, Oman, Ethiopia, Somalia, and Djibouti), Russia, Siberia, India, Sri Lanka, Tibet, Bhutan, western China, and Mongolia. Various lakes, seas, rivers, and islands are shown, along with several pieces of film footage of sunsets, moon sets, clouds, and tropical storms. Each film clip has a heading that names the shuttle and the geographical location of the footage.

Source record↗
NASA NTRS1996

STS-74 Mission Highlights Resource Tape

The flight crew of the STS-74 Space Shuttle Orbiter Atlantis Cmdr. Ken Cameron, Pilot Jim Halsell, and Mission Specialists Chris Hadfield, Jerry Ross, and William McArthur present an overview of their flight mission, whose primary objective is the rendezvous and space docking with the Russian Mir Space Station. Video film footage includes the following: prelaunch and launch activities; shuttle launch; in-orbit rendezvous; installation of the Russian-made docking module; in-orbit docking between Mir and the orbiter; general crew activities; transfer of supplies, equipment, and a crystal growth experiment to Mir; data collection from Mir thruster firings; undocking maneuvers and a Mir fly around; pre-return checkout of flight systems; and the reentry and landing of the orbiter. Earth views include horizon sunsets, atmospheric boundary layers, and a variety of geographical location footage (New Orleans; Atlanta; James Bay, Canada; Poland; Turkey; Mt. Pinatubo, Philippines; Salt Lake City, Utah; and Colorado).

Source record↗
NASA NTRS1997

Total Solar Eclipse of 1999 August 11

On 1999 August 11, a total eclipse of the Sun will be visible from within a narrow corridor which traverses the Eastern Hemisphere. The path of the Moon's umbral shadow begins in the Atlantic and crosses central Europe, the Middle East, and India, where it ends at sunset in the Bay of Bengal. A partial eclipse will be seen within the much broader path of the Moon's penumbral shadow, which includes northeastern North America, all of Europe, northern Africa, and the western half of Asia. Detailed predictions for this event are presented and include besselian elements, geographic coordinates of the path of totality, physical ephemeris of the umbra, topocentric limb profile corrections, local circumstances for approximately 1400 cities, maps of the eclipse path, weather prospects, the lunar limb profile, and the sky during totality. Tips and suggestions are also given on how to safely view and photograph the eclipse.

Espenak, Fred↗
NASA NTRS1997

STS-83 Postflight Presentation

The flight crew of the STS-83 mission, Cmdr James D. Halsell, Pilot Susan S. Still, Payload Cmdr. Janice E. Voss, Mission Specialists Donald Thomas and Michael Gernhardt, and Payload Specialists Roger Crouch and Greg Linteris, offer a video and still photo presentation of their journey. Included in the presentation are an introduction of the crew and a short briefing by Cmdr. Halsell, the launch and ascent narrated by Still, Spacelab Module narration by Voss, mission control narrated by Cmdr. Halsell, experiment narration by Thomas and Crouch. Also included are video views of the Baja Peninsula, Sinai Peninsula, pivot-point irrigation circles, Comet Hale-Bopp, and the cross-wind landing. The crew poses outside the shuttle for photos. Crew members discuss still photos taken during the mission, including shots of sunsets, the Grand Bahamas Island, Nile River, Baja Peninsula, Indis River of India, and Guadalupe Island.

Source record↗
NASA NTRS1993

An Overview of the Relevant Results from the ATMOS Missions of 1985 and 1992

The Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment employs a Fourier transform spectrometer to record infrared solar spectra at orbital sunrises and sunsets from on board the Space Shuttle. The data returned from 19 occultations covered by the instrument's first flight as part of the Spacelab 3 payload in April, 1985, have been analyzed for the profiles of some thirty atmospheric constituents. These results included a number of species not previously detected or measured, an investigation of the NO(y) and Cl(x) budgets, and, as a whole, have been used as the input for critically evaluating stratospheric photochemical models. The instrument was flown again on the ATLAS-1 shuttle mission in March, 1992, where it obtained data through nearly 100 solar occultation events located between latitudes of 30 deg N and 55 deg S. Results from the 1985 mission as well as preliminary results from the more recent 1992 flight are summarized here.

Gunson, Michael R.↗
NASA NTRS1997

Observed Changes in Atmospheric Boundary Layer Properties at Memphis International Airport During August 1995

As part of the NASA Terminal Area Productivity Program, Langley Research Center embarked on a series of field measurements of wake vortex characteristics and associated atmospheric boundary layer properties. One measurement period was at the Memphis International Airport in August 1995. Atmospheric temperature, humidity, winds, turbulence, radiation, and soil properties were measured from a variety of sensor systems and platforms including sodars, profilers, aircraft and towers. This research focused on: (1) changes that occurred in tower data during sunrise and sunset transitions, (2) vertical variation of temperature and cross-head winds at selected times utilizing combinations of sensors, and (3) changes measured by an OV-10 aircraft during approaches and level flights. Significant but not unusual changes are documented and discussed in terms of expected boundary layer behavior. Questions on measurement and prediction of these changes from existing and near-term capabilities are discussed in the context of a future Aircraft Vortex Spacing System.

Zak, J. Allen↗
NASA NTRS1997

Temporal, Spatial, and Diurnal Patterns in Avian Activity at the Shuttle Landing Facility, John F. Kennedy Space Center, Florida, USA

Spatial and temporal patterns in bird abundance within the five-mile airspace at the Shuttle Landing Facility (SLF) on John F. Kennedy Space Center (KSC), Florida, USA were investigated for purposes of quantifying Bird Aircraft Strike Hazards (BASH). The airspace is surrounded by the Merritt Island National Wildlife Refuge (MINWR) which provides habitat for approximately 331 resident and migratory bird species. Potential bird strike hazards were greatest around sunrise and sunset for most avian taxonomic groups, including wading birds, most raptors, pelicans, gulls/terns, shorebirds, and passerines. Turkey Vultures and Black Vultures were identified as a primary threat to aircraft operations and were represented in 33% of the samples. Diurnal vulture activity varied seasonally with the development of air thermals in the airspace surrounding the SLF. Variation in the presence and abundance of migratory species was shown for American Robins, swallows, and several species of shorebirds. Analyses of bird activities provides for planning of avionics operations during periods of low-dsk and allows for risk minimization measures during periods of high-risk.

Larson, Vickie L.↗
NASA NTRS1998

Tropospheric- Stratospheric Measurement Studies Summary

The two high altitude aircraft, ER-2 NASA #706 and 709 and the DC-8 NASA #717 are in active use in several programs of upper atmospheric research to study polar ozone changes, stratospheric-tropospheric exchange processes and atmospheric effects of aviation aircraft. The ER-2 has participated in seven major missions which mainly concentrated on vortex dynamics and the large losses of Ozone in the Polar regions (Ozone hole) observed in the spring. One mission verified the complex dynamical chemical and physical processes that occur during sunrise and sunset. Stratospheric Tracers of Atmospheric Transport (STRAT) obtained background measurements using the full ER-2 suite of instruments. Photochemistry of Ozone Loss in the Arctic Region in Summer (POLARIS) in 1997 assisted in understanding the mid-latitude and Arctic Ozone losses during the Northern Summer. The DC-8 with the Meteorological Measurement System (MMS) has participated in the Subsonic Aircraft: Cloud and Contrail Effects Special Study (SUCCESS), in 1996 and the Subsonic assessment Ozone and Nitrogen oxide experiment (SONEX) in 1997 missions. The MMS with its sophisticated software accurately measures ground speed and attitude, in-situ static and dynamic pressure total temperature, which are used to calculate the three dimensional wind fields, static pressure, temperature and turbulence values to meteorological accuracy. The meteorological data is not only of interest for its own sake in atmospheric dynamical processes such as mountain waves and flux measurements; but is also required by other ER-2 experiments that simultaneously measure water vapor, O3, aerosols, NO, HCl, CH4, N2O, ClO, BrO, CO2, NOy, HOx and temperature gradients. MMS products are extensively used to assist in the interpretation of their results in understanding the importance of convective effects relative to in-situ chemical changes, as may be noted by examining the list of references attached. The MMS consists of three subsystems: (a) aircraft instrumentation, inertial navigation system (INS), static and dynamic pressure taps, (b) additional dedicated instrumentation measuring angle of attack, yaw, total temperature, and a GPS which on the DC-8 measures position, velocity and attitude (c) an on board data, storage and computing acquisition system. This instrumentation and the associated software requires both an on-going laboratory ground calibration procedure for the total air temperature, static and total pressure inputs, verification of the INS dynamic response and also extensive air measurements and intercomparisons which ultimately verify and calibrate the complete system and its software. More than the usual accuracy is required because of the near cancellation occurring in the difference between the ground speed and true airspeed vectors used to give the wind vector. In the past year we have redesigned, recalibrated and used the MMS system on the NASA DC-8 that was previously used in the SUCCESS mission for the SONEX mission. Two papers were co-authored based on SUCCESS flights. Several reports and handouts were written for SONEX. Calibrations of the DC-8 pressure transducer temperature measuring thermistors was completed and an extensive analysis spanning several years of data files of the DC-8 Rosemount pressure transducer calibrations was done.

Browen, Stuart W.↗
NASA NTRS1999

Measuring Thermal Characteristics of Urban Landscapes

The additional heating of the air over the city is the result of the replacement of naturally vegetated surfaces with those composed of asphalt, concrete, rooftops and other man-made materials. The temperatures of these artificial surfaces can be 20 to 40 C higher than vegetated surfaces. Materials such as asphalt store much of the sun's energy and remains hot long after sunset. This produces a dome of elevated air temperatures 5 to 8 C greater over the city, compared to the air temperatures over adjacent rural areas. This effect is called the "urban heat island". Urban landscapes are a complex mixture of vegetated and nonvegetated surfaces. It is difficult to take enough temperature measurements over a large city area to characterize the complexity of urban radiant surface temperature variability. However, the use of remotely sensed thermal data from airborne scanners are ideal for the task. In a study funded by NASA, a series of flights over Huntsville, Alabama were performed in September 1994 and over Atlanta, Georgia in May 1997. Analysis of thermal energy responses for specific or discrete surfaces typical of the urban landscape (e.g., asphalt, building rooftops, vegetation) requires measurements at a very fine spatial scale (i.e., <15 m) to adequately resolve these surfaces and their attendant thermal energy regimes. Additionally, very fine scale spatial resolution thermal infrared data, such as that obtained from aircraft, are very useful for demonstrating to planning officials, policy makers, and the general populace, what the benefits are of the urban forest in both mitigating the urban heat island effect, in making cities more aesthetically pleasing and more habitable environments, and in overall cooling of the community. In this presentation we will examine the techniques of analyzing remotely sensed data for measuring the effect of various urban surfaces on their contribution to the urban heat island effect.

Luvall, Jeffrey C.↗