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All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Light Improves Alertness and Mood during the Sleep Inertial Period following Slow Wave Sleep

Introduction: Waking from sleep, especially slow wave sleep (SWS), is associated with reduced alertness known as sleep inertia. Light improves alertness during sleep deprivation and circadian misalignment. In this study, we assessed the efficacy of light to improve alertness and mood immediately after waking from SWS. Methods: Twelve participants kept a sleep schedule of 8.5 h for 5 nights and 5 h for one night prior to the overnight laboratory visit (confirmed by actigraphy). Participants went to bed at their scheduled habitual bedtime in the laboratory and were monitored by standard polysomnography. After at least 5 min of SWS, participants were awoken and exposed to either red ambient light (control) or blue-enriched bright light (light) for 1 h. During this time, participants completed a subjective scale of alertness (Karolinska Sleepiness Scale, KSS) and visual analogue scales (VAS) of mood at 2 min, 17 min, 32 min, and 47 min after waking. Following this sleep inertia measurement period, all lights were turned off and participants were allowed to return to sleep. They were then awoken again from their subsequent SWS period and exposed to the opposite condition (control or light). A linear mixed-effects model with fixed effects of condition, time, and condition*time and a random effect of participant was used to determine the impact of light across the testing period. An average of baseline responses (pre-sleep) was included as a covariate. Results: Compared to the control condition, participants exposed to bright blue-enriched light reported feeling more alert (KSS: F1,77=4.955, p=.029; VASalert: F1,77=8.226, p=.005), more cheerful (VAScheerful: F1,77=8.615, p=.004), less depressed (VASdepressed: F1,77=4.649, p=.034), and less lethargic (VASlethargic: F1,77=5.652, p=.020). Discussion: Exposure to blue-enriched bright light immediately after waking from SWS may help to improve subjective alertness and mood. Future analyses will explore whether these findings extend to effects on cognitive performance.

alertness↗
NASA NTRS2013

Conceptual Design of the Adaptive Optics System for the Laser Communication Relay Demonstration Ground Station at Table Mountain

The Laser Communication Relay Demonstration will feature a geostationary satellite communicating via optical links to multiple ground stations. The first ground station (GS-1) is the 1m OCTL telescope at Table Mountain in California. The optical link will utilize pulse position modulation (PPM) and differential phase shift keying (DPSK) protocols. The DPSK link necessitates that adaptive optics (AO) be used to relay the incoming beam into the single mode fiber that is the input of the modem. The GS-1 AO system will have two MEMS Deformable mirrors to achieve the needed actuator density and stroke limit. The AO system will sense the aberrations with a Shack-Hartmann wavefront sensor using the light from the communication link's 1.55 microns laser to close the loop. The system will operate day and night. The system's software will be based on heritage software from the Palm 3000 AO system, reducing risk and cost. The AO system is being designed to work at r(sub 0) greater than 3.3 cm (measured at 500 nm and zenith) and at elevations greater than 20deg above the horizon. In our worst case operating conditions we expect to achieve Strehl ratios of over 70% (at 1.55 microns), which should couple 57% of the light into the single mode DPSK fiber. This paper describes the conceptual design of the AO system, predicted performance and discusses some of the trades that were conducted during the design process.

optical communications↗
NASA NTRS1998

Ground-based studies with Super-Dwarf wheat in preparation for space flight

Several experiments were carried out to test responses of a Super-Dwarf cultivar of wheat (Triticum aestivum L.) to various environmental parameters that were anticipated to be present in our attempts to grow the wheat in a small growth chamber on the Russian Space Station, Mir, or that proved to be present in a 1995 trial space experiment. Under low photosynthetic photon flux (40-400 micromoles m-2 s-1 PPF), development (e.g. anthesis) was retarded, but heads (often sterile) always formed, even if light was so low that plants died before the heads could mature. Longer photoperiods promoted flowering, but night interruptions combined with short days did not provoke a long-day response as occurs with true long-day plants. The long-day effect could prove to be a summation of photosynthetic products. Heat stress (40 degrees C for 1-24 h) did not influence flowering but killed plants that were 13-16-day-old (no effect on younger plants). Concentrations of iodine or silver-fluoride disinfectants present in the water used for plants on Mir (1.0-4.0 mg L-1) did not affect plant growth although higher concentrations (8.0-1.6 mg L-1) were inhibitory. GA3 or indoleacetic acid applied every other day at concentrations from 1.0 x 10(-6) mg L-1 to 3.162 x 10(-4) mg L-1 did not change the height of Super-Dwarf wheat, suggesting that this cultivar is not a gibberellin mutant.

Flight Experiment↗
NASA NTRS1972

Functional characteristics of the OGO main body airglow photometer

The OGO-4 main body airglow photometer used a trialkali cathode photomultiplier to sense light at selected wavelengths between 2500 and 6300A corresponding to important emissions in the aurora and night airglow at emission rates ranging from a few rayleighs to about 200 kilorayleighs. The optical, electronic, and mechanical systems are described in terms of their functional characteristics.

Reed, E. I.↗
NASA NTRS1973

UBV photometry of Iapetus.

UBV observations of Iapetus on 34 nights have revealed a 0.30-mag difference in the depths of two successive minima in the light curve of this satellite. The difference can be explained by a two-hemisphere model with the leading darker hemisphere having a much stronger variation in brightness with solar phase angle than the trailing brighter hemisphere. Aside from the variation in the depths of the minima, the general character of the light and color curves is similar to that reported by earlier investigators.

Millis, R. L.↗
NASA NTRS1983

Integrated Power/Attitude Control System (IPACS)

During orbit day, solar energy collected by the solar cell arrays and transformed into electrical energy is used to power the spacecraft subsystems, including the control system. In conventional spacecraft designs, a portion of the energy collected during the light portion of the orbit is stored in a set of batteries for use during orbit night. In the Integrated Power/Attitude Control System (IPACS) approach, that energy is stored in the rotating flywheel in the form of kinetic energy. Umbra electrical power demands are satisfied by attaching a generator to the wheel shaft and despinning the rotor. Through this approach, the battery system is no longer required and thus is eliminated.

Keckler, C. R.↗
NASA NTRS2019

Low-Dose Caffeine Administration During Acute Sleep Deprivation Eliminates Visual Motion Processing Impairment, but Does Not Improve Saccadic Rate

Oculomotor tracking performance changes according to time awake. A constant routine (CR) study demonstrated that increasing time awake 1) reduces the precision of visual motion processing, 2) decreases steady-state closed-loop pursuit performance and 3) decreases peak saccadic velocity. We aimed to determine the contribution of homeostatic sleep pressure on these oculometric changes by administering low-dose caffeine over one night of sleep deprivation. Participants completed two weeks of at-home 8.5 hours sleep per day, followed by an approximately 24-hour laboratory CR in semi-recumbent posture under less than 4 lux of light. The visual tracking task was performed every two hours after waking and hourly overnight. Low-dose caffeine of 0.3 milligrams per kilogram was administered hourly during the biological night. Nine participants (5F) completed the study. Caffeine dosing: 1) prevented the impairment of visual motion processing, 2) reduced by approximately half the impairment of closed-loop pursuit performance (gain, minus 0.47 percent per hour, significance of slope change: p (probability) less than 0.006; proportion smooth, minus 0.35 percent per hour, p less than 0.005), and 3) had an insignificant (p less than 0.39) effect on the impairment of saccadic peak velocity (slope, minus 1.13 percent per hour; intercept, minus 0.62 percent per hour). These results suggest that visual motion processing and some proportion of closed-loop pursuit performance are impaired due to homeostatic mechanisms during sleep deprivation.

Sleep↗
NASA NTRS1991

Deimos: A featureless asteroid-like spectrum

High quality CCD spectra were obtained of Deimos from 0.5 to 1.0 micron at a spectral resolution of 15A at the time of the 1988 Mars opposition. The data acquisition and reduction methods allowed the quantitative prevention of scattered light from Mars contaminating the spectra. Solar analog stars BS560, BS2007, and BS8931 were observed the same night to allow removal of telluric absorptions. The ratio spectrum of Deimos has a red slope, increasing in reflectance by a factor of approx. 50 pct. over the one octave wavelength interval observed. Other than this slope, the spectrum is remarkably featureless. The absence of absorption bands in the spectrum of Deimos is in marked contrast with the spectra of Martian surface materials. No trace of the Fe(2+) charge transfer absorption band around 1 micron is observed, which rules out the presence of significant quantities of minerals such as the pyroxenes or olivine at the surface of Deimos. The featureless red spectrum of Deimos appears to be consistent with a surface composition of fine grained carbonaceous chondrite type material. An analysis is presented of the spectrum of Deimos which makes use of the Hapke scattering surface model.

Grundy, W. M.↗
NASA NTRS1976

Photometer calibration error using extended standard sources

As part of a project to compare measurements of the night airglow made by the visible airglow experiment on the Atmospheric Explorer-C satellite, the standard light sources of several airglow observatories were compared with the standard source used in the absolute calibration of the satellite photometer. In the course of the comparison, it has been found that serious calibration errors (up to a factor of two) can arise when a calibration source with a reflecting surface is placed close to an interference filter. For reliable absolute calibration, the source should be located at a distance of at least five filter radii from the interference filter.

Torr, M. R.↗
NASA NTRS2011

Observations of Leonids 2009 by the Tajikistan Fireball Network

The fireball network in Tajikistan has operated since 2009. Five stations of the network covering the territory of near eleven thousands square kilometers are equipped with all-sky cameras with the Zeiss Distagon "fish-eye" objectives and by digital SLR cameras Nikon with the Nikkor "fish-eye" objectives. Observations of the Leonid activity in 2009 were carried out during November 13-21. In this period, 16 Leonid fireballs have been photographed. As a result of astrometric and photometric reductions, the precise data including atmospheric trajectories, velocities, orbits, light curves, photometric masses and densities were determined for 10 fireballs. The radiant positions during the maximum night suggest that the majority of the fireball activity was caused by the annual stream component with only minor contribution from the 1466 trail. According to the PE criterion, the majority of Leonid fireballs belonged to the most fragile and weak fireball group IIIB. However, one detected Leonid belonged to the fireball group I. This is the first detection of an anomalously strong Leonid individual.

Borovicka, J.↗
NASA NTRS2002

Astronauts Need Their Rest Too: Sleep-Wake Actigraphy and Light Exposure During Space Flight

The success and effectiveness of human space flight depends on astronauts' ability to maintain a high level of cognitive performance and vigilance. This alert state ensures the proper operation of sophisticated instrumentation. An important way for humans to remedy fatigue and maintain alertness is to get plenty of rest. Astronauts, however, commonly experience difficulty sleeping while in space. During flight, they may also experience disruption of the body's circadian rhythm - the natural phases the body goes through every day as we oscillate between states of high activity during the waking day and recuperation, rest, and repair during nighttime sleep. Both of these factors are associated with impairment of alertness and performance, which could have important consequences during a mission in space. The human body was designed to sleep at night and be alert and active during the day. We receive these cues from the time of day or amount of light, such as the rising or setting of the sun. However, in the environment of the Space Shuttle or the International Space Station where light levels are highly variable, the characteristics of a 24-hour light/dark cycle are not present to cue the astronauts' bodies about what time of the day it is. Astronauts orbiting Earth see a sunset and sunrise every 90 minutes, sending potentially disruptive signals to the area of the brain that regulates sleep. On STS-107, researchers will measure sleep-wake activity with state-of-the-art technology to quantify how much sleep astronauts obtain in space. Because light is the most powerful time cue to the body's circadian system, individual light exposure patterns of the astronauts will also be monitored to determine if light exposure is associated with sleep disruption. The results of this research could lead to the development of a new treatment for sleep disturbances, enabling crewmembers to avoid the decrements in alertness and performance due to sleep deprivation. What we learn about sleep in space informs treatment for earthbound populations, such as the elderly and insomniacs, who experience frequent sleep disturbances or altered sleep patterns.

Czeisler, Charles↗
NASA NTRSDate not supplied

Blue-enriched Light Improves Alertness and Mood Following Abrupt Awakening from Slow Wave Sleep

INTRODUCTION: All crew on the International Space Station (ISS) have a sleep opportunity at the same time. Emergencies arising during this time require all crew members to be abruptly awoken from sleep and to be alert, ready to work as a team, and to perform safety-critical tasks soon after waking. However, crew may experience sleep inertia after waking, which is associated with reduced alertness, poor mood, and impaired performance, especially if woken from deep sleep (slow wave sleep, SWS). Light has been shown to improve alertness during sleep deprivation and circadian misalignment. In this study, we assessed the efficacy of blue-enriched light to improve alertness and mood immediately after waking from SWS, i.e., during the sleep inertia period. METHODS: Twelve participants kept a sleep schedule of 8.5 h for 5 nights and 5 h for one night prior to the overnight laboratory visit (confirmed by actigraphy). Participants went to bed at their scheduled habitual bedtime in the laboratory and were monitored by standard polysomnography. After at least 5 min of SWS, participants were awoken and exposed to either red ambient light (control) or blue-enriched light (light) for 1 h. During this time, participants completed a subjective scale of alertness (Karolinska Sleepiness Scale, KSS) and visual analogue scales (VAS) of mood at 2 min, 17 min, 32 min, and 47 min after waking. Following this sleep inertia measurement period, all lights were turned off and participants were allowed to return to sleep. They were then awoken again from their subsequent SWS period and exposed to the opposite condition (control or light). A linear mixed-effects model with fixed effects of condition, time, and condition*time and a random effect of participant was used to determine the impact of light across the testing period. An average of baseline responses (pre-sleep) was included as a covariate. RESULTS: Compared to the control condition, participants exposed to blue-enriched light reported feeling more alert (KSS: F1,77=4.955, p=.029; VASalert: F1,77=8.226, p=.005), more cheerful (VAScheerful: F1,77=8.615, p=.004), less depressed (VASdepressed: F1,77=4.649, p=.034), and less lethargic (VASlethargic: F1,77=5.652, p=.020). DISCUSSION: Exposure to blue-enriched light immediately after waking from SWS may help to improve subjective alertness and mood. Future analyses will explore whether these findings extend to effects on cognitive performance. This countermeasure to sleep inertia may be suitable for implementation to alert crew members during mid-sleep emergencies but requires further testing in field settings.

alertness↗
NASA NTRSDate not supplied

Rise and Shine: Using Light as a Countermeasure to Sleep Inertia

INTRODUCTION: Sleep inertia describes the phenomenon of sleepiness and poor performance experienced after waking from sleep. This period of impaired alertness and performance is of significant concern to workers who nap on shift, or work on-call and are required to perform safety-critical tasks soon after waking (e.g., emergency services, healthcare, military). Light has been shown to acutely improve alertness during sleep deprivation and circadian misalignment. In this study, we assessed the efficacy of blue-enriched light to improve alertness and mood immediately after waking from SWS, i.e., during the sleep inertia period. METHODS: Twelve participants kept a sleep schedule of 8.5 h for 5 nights and 5 h for one night prior to the overnight laboratory visit (confirmed by actigraphy). Participants went to bed at their scheduled habitual bedtime in the laboratory and were monitored by standard polysomnography. After at least 5 min of SWS, participants were awoken and exposed to either red ambient light (control) or blue-enriched light (light) for 1 h. During this time, participants completed a subjective scale of alertness (Karolinska Sleepiness Scale, KSS) and visual analogue scales (VAS) of mood at 2 min, 17 min, 32 min, and 47 min after waking. Following this sleep inertia measurement period, all lights were turned off and participants were allowed to return to sleep. They were then awoken again from their subsequent SWS period and exposed to the opposite condition (control or light). A linear mixed-effects model with fixed effects of condition, time, and condition*time and a random effect of participant was used to determine the impact of light across the testing period. An average of baseline responses (pre-sleep) was included as a covariate. RESULTS: Compared to the control condition, participants exposed to blue-enriched light reported feeling more alert (KSS: F1,77=4.955, p=.029; VASalert: F1,77=8.226, p=.005), more cheerful (VAScheerful: F1,77=8.615, p=.004), less depressed (VASdepressed: F1,77=4.649, p=.034), and less lethargic (VASlethargic: F1,77=5.652, p=.020). DISCUSSION: Exposure to blue-enriched light immediately after waking from SWS may help to improve subjective alertness and mood. Future analyses will explore whether these findings extend to effects on cognitive performance. This countermeasure to sleep inertia may be suitable for implementation to alert crew members during mid-sleep emergencies but requires further testing in field settings.

alertness↗
NASA NTRS1986

Controlled environment life support system: Calcium-related leaf injuries on plants

Calcium related injuries to plants grown in controlled environments under conditions which maximize plant growth rates are described. Procedures to encourage movement of calcium into developing leaves of lettuce plants were investigated. The time course and pattern of calcium accumulation was determined to develop effective control procedures for this injury, termed tipburn. Procedures investigated were: (1) increasing the relative humidity to saturation during the dark period and altering root temperatures, (2) maximizing water stress during light and minimizing water stress during dark periods, (3) shortening the light-dark cycle lengths in combination with elevated moisture levels during the dark cycles, (4) reducing nutrient concentrations and (5) vibrating the plants. Saturated humidities at night increased the rate of growth and the large fluctuation in plant water potential encouraged calcium movement to the young leaves and delayed tipburn. Root temperature regulation between 15 and 26 C was not effective in preventing tipburn. Attempts to modulate water stress produced little variation, but no difference in tipburn development. Variations in light-dark cycle lengths also had no effect on calcium concentrations within developing leaves and no variation in tipburn development. Low concentrations of nutrient solution delayed tipburn, presumably because of greater calcium transport in the low concentration plants. Shaking of the plants did not prevent tipburn, but did delay it slightly.

Tibbitts, T. W.↗
NASA NTRS1983

Limited flight test experience with a laser transit velocimeter

Limited flight testing of a laser transit velocimeter provided insight into the problems associated with the use of such instruments for flight research. Although the device tested was not designed for flight application, it had certain features such as fiber optics and low laser power which are attractive in the airborne environment. During these tests, operation of the velocimeter was limited by insufficient concentrations of light-scattering particles and background light interference. Normal operation was observed when these conditions were corrected by utilizing cloud particles and flying at night. A comparison between the laser flow velocity measurements and corresponding pressure measurements is presented and shows a coarse correlation. Statistical bias due to turbulence in the flow is suspected to have affected the laser measurements.

Curry, R. E.↗
NASA NTRS1990

Aircraft measurements of the mean and turbulent structure of marine stratocumulus clouds during FIRE

The mean and turbulent structure of marine stratocumulus clouds is defined from data that were collected from 10 flights made with the National Center for Atmospheric Research (NCAR) Electra during the First ISCCP Regional Experiment (FIRE). The number of cases sampled is sufficiently large that researchers can compare the boundary layer structure obtained (1) for solid and broken cloud conditions, (2) for light and strong surface wind conditions, (3) for different sea-surface temperatures, and (4) on day and night flights. Researchers will describe the cloud and synoptic conditions present at the time of the Electra flights and show how those flights were coordinated with the operations of other aircraft and with satellite overpasses. Mean thermodynamic and wind profiles and the heat, moisture, and momentum fluxes obtained from data collected during these flights will be compared. Variations in the cloud-top structure will be quantified using LIDAR data collected during several of the Electra flights. The spatial structure of cloud-top height and the cloud-base height will be compared with the turbulent structure in the boundary layer as defined by spectra and cospectra of the wind, temperature, and moisture.

Albrecht, Bruce A.↗
NASA NTRS1991

CVF spectrophotometry of Pluto - Correlation of composition with albedo

The present time-resolved, 0.96-2.65-micron spectrophotometry for the Pluto-Charon system indicates night-to-night variations in the depths of the methane absorptions such that the bands' equivalent width is near minimum light. The interpretation of these data in terms of a depletion of methane in dark regions of the planet, relative to bright ones, is consistent with the Buie and Fink (1987) observations. The near-IR spectrum of Pluto seems to be dominated by surface frost. It is suggested that the dark equatorial regions of Pluto are redder than those of moderate albedo.

Marcialis, Robert L.↗
NASA NTRS2013

Ultra-Thin Coatings Beautify Art

The craftsmen in the Roman Empire who constructed the Lycurgus Cup 17 centuries ago probably didn't think their artifact would survive for nearly 2,000 years as a prized possession. And they certainly couldn't have known that the technology they used to make it would eventually become an important part of space exploration. Carved from one solid mass, the cup is one of the few complete glass objects from that period, and the only one made from dichroic glass. Meaning "two-colored" in Greek, dichroic glass was originally created by adding trace amounts of gold and silver to a large volume of glass melt. The resulting medium partially reflects the light passing through it, causing an observer to see different colors depending on the direction of the light source. The Lycurgus Cup, for example, is famous for appearing green in daylight and red when lit at night, symbolic of the ripening grapes used to fill it with wine. NASA revitalized the production of dichroic glass in the 1950s and 1960s as a means of protecting its astronauts. Ordinary clear substances cannot protect human vision from the harsh rays of unfiltered sunlight, and everything from the human body to spacecraft sensors and computers are at risk if left unprotected from the radiation that permeates space. The microscopic amounts of metal present in dichroic glass make it an effective barrier against such harmful radiation. While the ancient manufacturing technique called for adding metals to glass melt, NASA developed a process in which metals are vaporized by electron beams in a vacuum chamber and then applied directly to surfaces in an ultra-thin film. The vapor condenses in the form of crystal structures, and the process is repeated for up to several dozen coatings. The resulting material, still only about 30 millionths of an inch thick, is sufficient to reflect radiation even while the glass, or polycarbonate, as in the case of space suit helmets, remains transparent to the human eye.

Source record↗