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Development of optic disc edema during 30 days of hypercapnic head down tilt bed rest is associated with short sleep duration and blunted temperature amplitude

Consequences of sleep and circadian rhythm disturbances include many neurophysiological sequelae, especially when combined with spaceflight stressors, and are therefore hypothesized to contribute to the development of optic disc edema observed in astronauts. Additionally, chronically elevated carbon dioxide (CO 2 ) levels on the International Space Station may contribute to the observed sleep disturbances in astronauts. Here we determined if the spaceflight analogue head-down tilt bed rest (HDTBR) combined with elevated CO 2 levels influenced sleep and core temperature and was associated the development of optic disc edema. Healthy participants (5 female, 6 male) aged 25-50 years, underwent thirty days of strict 6° HDTBR in a mild hypercapnic environment (ambient PCO 2 = 4 mmHg) with measures of sleep, 24-hour core temperature, overnight arterialized CO2, and Frisén grade edema collected pre-HDTBR, on HDTBR days 4, 17, 28, and post-HDTBR days 4 and 10. During all HDTBR time points, sleep, core temperature, and overnight arterialized CO 2 were not statistically significantly different than the pre-HDTBR measurements. However, independent of the HDTBR intervention, the odds ratios (mean [95% CI]) for developing Frisén grade optic disc edema were statistically significant for each hour below the mean total sleep time (2.2 [1.1-4.4]) and stage 2 NREM sleep (4.8 [1.3-18.6]), and above the mean for wake after sleep onset (3.6 [1.2-10.6]) and for each 0.1°C decrease in core temperature amplitude below the mean (4.0 [1.4-11.7]).These data suggest that optic disc edema occurring during HDTBR was more likely to occur in those with short sleep duration and blunted temperature amplitude.

Kate H. Christian↗

The NASA Space Shuttle Earth Observations Office

The NASA Space Shuttle Earth Observations Office conducts astronaut training in earth observations, provides orbital documentation for acquisition of data and catalogs, and analyzes the astronaut handheld photography upon the return of Space Shuttle missions. This paper provides backgrounds on these functions and outlines the data constraints, organization, formats, and modes of access within the public domain.

Helfert, Michael R.↗

Contribution of Spaceflight Environmental Factors to Vision Risks

The risk of visual impairment and elevated intracranial pressure as a result of low-earth orbit microgravity exposure has directed our attention and research efforts to the eye. While the alterations observed in astronauts returning from long duration missions include vision and neuroanatomical changes observed by non-invasive methods, other effects and subsequent tissue responses at the molecular and cellular level can only be studied by accessing the tissue itself. As a result of this need, several studies are currently taking place within the Human and Health Countermeasures Element (HHC) that use animal models for eye research. The rodent eye has many similarities to the human eye, and both rats and mice have historically been used as models of human eye disease, aiding in the identification of the disease genes, elucidation of mechanisms of disease, as well as in the assessment of therapeutic treatments. These studies attempt to answer two central questions in the etiology of possible vision alterations in the environment of space exploration missions. The first is: what effects and response mechanisms take place in the different eye structures at the cellular and molecular level? The second question is directed to elucidate the contribution of the various environmental stressors (radiation, nutrition, fluid shift) to these effects. Collaborative approaches with internal and external investigators have allowed performing these studies in a most cost-effective fashion, providing preliminary data and laying the bases for testing further hypotheses in future and specifically designed animal experiments. From a study centered on the radioadaptive response in mice, we have learned that the retina responds to low and high dose gamma radiation by elevating antioxidant-related genes at early time points (4hrs) and that this response returns to control levels after 1 day post-irradiation. We are expanding this research with another collaborative study that investigates the combined effects of radiation exposure and iron overload on sensitivity to radiation injury in rat eyes. All main eye structures will be analyzed in this study: retina, lens and cornea. A study in collaboration with the Space Human Factors and Habitability Element (SHFH) investigates the effects of lunar dust exposure on the rat cornea. It is anticipated that common underlying oxidative stress mechanisms of damage may be observed as a result of these three stressors: radiation, nutritional iron and lunar dust. The contribution of fluid shift is addressed by a study using rats subjected to hindlimb suspension. The hypothesis to be tested in this study is that the mechanical stress imparted by the pressure differential across the optic disc and lamina cribosa will impact oxygenation (therefore causing oxidative stress and hypoxia) and cell survival. This study also includes the assessment of two nutritional antioxidant countermeasures: epigallocatechin gallate (green tea) and resveratrol. Finally, as a result of two successful tissue sharing efforts, we are proceeding with the analysis of eye samples of mice aboard two shuttle missions: STS-133 and STS-135. Results from the STS-133 study are presented in an independent abstract. Briefly, the results show that spaceflight represents a source of environmental stress that directly translates into oxidative and cellular stress in the retina. Similar analysis is also planned for the cornea. These samples add large value to our current vision research as they provide data on the direct effects of low-earth orbit spaceflight on eye structures and physiology.

Zanello, Susana B.↗

Contribution of Spaceflight Environmental Factors to Vision Risks

The recognition of a risk of visual impairment and intracranial pressure increase as a result of spaceflight has directed our attention and research efforts to the eye. While the alterations observed in astronauts returning from long duration missions include reportable vision and neuroanatomical changes observed by non-invasive methods, other effects and subsequent tissue responses at the molecular and cellular level can only be studied by accessing the tissue itself. As a result of this need, several studies are currently taking place that use animal models for eye research within the HHC Element. The implementation of these studies represents a significant addition to the capabilities of the biomedical research laboratories within the SK3 branch at JSC.

Zanello, Susana↗

Survey and Chase: A New Method of Observations For The Michigan Orbital Debris Survey Telescope (MODEST)

For more than 40 years astronauts have been observing Earth, taking photographs or digital images from their spacecraft. Today, a robust program of observation from the International Space Station (ISS) has yielded hundreds of thousands of images of the Earth s surface collected since 2001. Seeing Earth through the eyes of an astronaut is exciting to the general public, and the images are popular in classrooms. Because the ISS has an orbital inclination of 51.6 degrees (the north-south limits of the orbit are at 51.6 degrees latitude), high latitude observations are common. Some of the most striking images collected include views of polar phenomena. Astronauts routinely pass above brilliant red and green aurora; view high, wispy clouds at the top of the atmosphere; or look down on glaciers and floating ice rafts. These images, framed and captured by humans, are easily interpreted by students and teachers. Astronaut observations provide a way to visualize complicated polar phenomena and communicate about them to students of all ages. Over the next two years, astronauts aboard the ISS will formally focus their observations on polar phenomena as participants in the International Polar Year (IPY). Imagery acquisition from the ISS will be coordinated with other IPY scientists staging studies and field campaigns on the ground. The imagery collected from the ISS will be cataloged and served on NASA s web-based database of images, http://eol.jsc.nasa.gov . The website allows investigators, students and teachers to search through the imagery, assemble image datasets, and download the imagery and the metadata. We display some of the most spectacular examples of polar imagery and demonstrate NASA s database of astronaut images of Earth.

Abercromby, Kira J.↗

The International Space Station Supports International Polar Year (IPY)

Every day, ISS astronauts photograph designated sites and dynamic events on the Earth's surface using digital cameras equipped with a variety of lenses. Depending on observation parameters, astronauts can collect high resolution (4-6 m pixel size) or synoptic views (lower resolution but covering very large areas) digital data in 3 (red-green-blue) color bands. ISS crews have daily opportunities to document a variety of high-latitude phenomena. Although lighting conditions, ground track and other viewing parameters change with orbital precessions and season, the 51.6o orbital inclination and 400 km altitude of the ISS provide the crew an unique vantage point for collecting image-based data of polar phenomena, including surface observations to roughly 65o latitude, and upper atmospheric observations that reach nearly to the poles. During the 2007-2009 timeframe of the IPY, polar observations will become a scientific focus for the CEO experiment; the experiment is designated ISS-IPY. We solicit requests from scientists for observations from the ISS that are coordinated with or complement ground-based polar studies. The CEO imagery website for ISS-IPY provides an on-line form that allows IPY investigators to interact with CEO scientists and define their imagery requests. This information is integrated into daily communications with the ISS astronauts about their Earth Observations targets. All data collected are cataloged and posted on the website for downloading and assimilation into IPY projects. Examples of imagery and detailed information about scientific observations from the ISS can also be downloaded from the ISS-IPY web site.

Evans, Cynthia A.↗

International Polar Year Observations From the International Space Station

Astronauts aboard the International Space Station (ISS) have several opportunities each day to observe and document high-latitude phenomena. Although lighting conditions, ground track and other viewing parameters change with orbital precessions and season, the 51.6 degree orbital inclination and 400 km altitude of the ISS provide the crew an excellent vantage point for collecting image-based data for IPY investigators. To date, the database of imagery acquired by the Crew Earth Observations (CEO) experiment aboard the ISS (http://eol.jsc.nasa.gov) contains more than 12,000 images of high latitude (above 50 degrees) events such as aurora, mesospheric clouds, sea-ice, high-latitude plankton blooms, volcanic eruptions, and snow cover. The ISS Program will formally participate in IPY through an activity coordinated through CEO entitled Synchronized Observations of Polar Mesospheric Clouds, Aurora and Other Large-scale Polar Phenomena from the ISS and Ground Sites. The activity will augment the existing collection of Earth images taken from the ISS by focusing astronaut observations on polar phenomena. NASA s CEO experiment will solicit requests by IPY investigators for ISS observations that are coordinated with or complement ground-based polar studies. The CEO imagery website (http://eol.jsc.nasa.gov) will provide an on-line form for IPY investigators to interact with CEO scientists and define their imagery requests. This information will be integrated into daily communications with the ISS crews about their Earth Observations targets. All data collected will be cataloged and posted on the website for downloading and assimilation into IPY projects.

Pettit, Donald R.↗

Hurricane Ike Deposits on the Bolivar Peninsula, Galveston Bay, Texas

In September 2008, Hurricane Ike made landfall on Galveston Bay, close to the NASA Johnson Space Center (JSC). The storm flooded much of the area with a storm surge ranging from 11 -20 feet. The Bolivar peninsula, the southeastern coast of Galveston Bay, experienced the brunt of the surge. Several agencies collected excellent imagery baselines before the storm and complementary data a few days afterward that helped define the impacts of the storm. In April of 2011, a team of scientists and astronauts from JSC conducted field mapping exercises along the Bolivar Peninsula, the section of the Galveston Bay coast most impacted by the storm. Astronauts routinely observe and document coastal changes from orbit aboard the International Space Station. As part of their basic Earth Science training, scientists at the Johnson Space Center take astronauts out for field mapping exercises so that they can better recognize and understand features and processes that they will later observe from the International Space Station. Using pre -storm baseline images of the Bolivar Peninsula near Rollover Pass and Gilchrist (NOAA/Google Earth Imagery and USGS aerial imagery and lidar data), the astronauts mapped current coastline positions at defined locations, and related their findings to specific coastal characteristics, including channel, jetties, and other developments. In addition to mapping, we dug trenches along both the Gulf of Mexico coast as well as the Galveston Bay coast of the Bolivar peninsula to determine the depth of the scouring from the storm on the Gulf side, and the amount of deposition of the storm surge deposits on the Bay side of the peninsula. The storm signature was easy to identify by sharp sediment transitions and, in the case of storm deposits, a layer of storm debris (roof shingles, PVC pipes, etc) and black, organic rich layers containing buried sea grasses in areas that were marshes before the storm. The amount of deposition was generally about 20 -25 cm; the local areas experiencing obvious deposition are readily obvious in post -Ike imagery of the region. We used a March 2010 aerial photograph from the NOAA -Google Earth collection because construction and vegetation recovery was minimal. Based on the before and after aerial imagery and the trenching data collected over two days, we can begin to characterize the material transported and deposited by Hurricane Ike along one stretch of the Bolivar peninsula. We summarize the results from our mapping and trenching data. The basic data collected 2.5 years after the storm are ephemeral as the storm deposits become reworked and overprinted by coastal processes, vegetation regrowth and reconstruction.

Evans, Cynthia A.↗

Observations of cosmic ray induced phosphenes

Phosphene observations by astronauts on flights near and far from earth atmosphere are discussed. It was concluded that phosphenes could be observed by the naked eye. Further investigation is proposed to determine realistic human tolerance levels for extended missions and to evaluate the need to provide special spacecraft shielding.

Chapman, P. K.↗

Quantitative observation of light flash sensations experiment MA-106

Light flashes caused by the interaction of cosmic particles with the visual apparatus have been observed by astronauts on all space missions since Apollo 11. This Apollo Soyuz Test Project experiment compared measurements of the observer's visual sensitivity with measurements of the ambient radiation environment and with the frequency and character of the flashes observed. The data obtained reveal a latitude dependence of the frequency of observed flashes. This distribution of flashes is correlated with the distribution of cosmic particles with stopping power greater than 15 keV/ micrometers in the eye. The interaction of dark adaptation, specific ionization, and range of particles in the retina as factors in the visualization of particle passage is discussed.

Budinger, T. F.↗

Visual phenomena induced by relativistic carbon ions with and without Cerenkov radiation

Exposing the human eye to individual carbon ions moving at relativistic speeds results in visual phenomena that include point flashes, streaks, and larger diffuse flashes. The diffuse flashes have previously been observed by astronauts in space but not in laboratory experiments with particles of high atomic number and energy. They are observed only when the nucleus moves fast enough to generate Cerenkov radiation.

Mcnulty, P. J.↗

Do Bare Rocks Exist on the Moon?

Astronaut surface observations and close-up images at the Apollo and Chang'e 1 landing sites confirm that at least some lunar rocks have no discernable dust cover. However, ALSEP (Apollo Lunar Surface Experiments Package) measurements as well as astronaut and LADEE (Lunar Atmosphere and Dust Environment Explorer) orbital observations and laboratory experiments possibly suggest that a fine fraction of dust is levitated and moves across and above the lunar surface. Over millions of years such dust might be expected to coat all exposed rock surfaces. This study uses thermal modeling, combined with Diviner (a Lunar Reconnaissance Orbiter experiment) orbital lunar eclipse temperature data, to further document the existence of bare rocks on the lunar surface.

Allen, Carlton↗

Eating in space--from an astronaut's perspective

Food systems and meal components are constantly under review and development at the National Aerospace and Space Administration. The goal of this work is to generate a diet that meets the nutrient requirements of astronauts and satiates them. The constraints involved in shorter- and longer-term missions are described. The insight provided by observations of astronauts from the Skylab and Shuttle eras will allow researchers to consider the fact that, for any nutritional regimen to work, it must consider the limitations and taste buds of the individuals involved. Otherwise, the best diet design generated by their work may never be consumed.

Review, Tutorial↗

Adaptive Responses in Eye-Head-Hand Coordination Following Exposures to a Virtual Environment as a Possible Space Flight Analog

Virtual environments (VE) offer unique training opportunities, particularly for training astronauts and preadapting them to the novel sensory conditions of microgravity. Sensorimotor aftereffects of VEs are often quite similar to adaptive sensorimotor responses observed in astronauts during and/or following space flight. The purpose of this research was to compare disturbances in sensorimotor coordination produced by dome virtual environment display and to examine the effects of exposure duration, and repeated exposures to VR systems. The current study examined disturbances in eye-head-hand (EHH) and eye-head coordination. Preliminary results will be presented. Eleven subjects have participated in the study to date. One training session was completed in order to achieve stable performance on the EHH coordination and VE tasks. Three experimental sessions were performed each separated by one day. Subjects performed a navigation and pick and place task in a dome immersive display VE for 30 or 60 min. The subjects were asked to move objects from one set of 15 pedestals to the other set across a virtual square room through a random pathway as quickly and accurately as possible. EHH coordination was measured before, immediately after, and at 1 hr, 2 hr, 4 hr and 6 hr following exposure to VR. EHH coordination was measured as position errors and reaction time in a pointing task that included multiple horizontal and vertical LED targets. Repeated measures ANOVAs were used to analyze the data. In general, we observed significant increases in position errors for both horizontal and vertical targets. The largest decrements were observed immediately following exposure to VR and showed a fairly rapid recovery across test sessions, but not across days. Subjects generally showed faster RTs across days. Individuals recovered from the detrimental effects of exposure to the VE on position errors within 1-2 hours. The fact that subjects did not significantly improve across days suggests that in order to achieve dual adaptation of EHH coordination may require more than three training sessions. These findings provide some direction for developing training schedules for VE users that facilitate adaptation, support the idea that preflight training of astronauts may serve as useful countermeasure for the sensorimotor effects of space flight, and support the idea that VEs may serve as an analog for sensorimotor effects of spaceflight.

Harm, Deborah L.↗

Angiotensin-(1-7) antagonist [D-Ala7-Ang-(1-7);A-779] attenuates post-suspension hypotension in Sprague-Dawley rats

Cardiovascular deconditioning manifested by reduction in mean arterial pressure (MAP) and cardioaccleration are usually observed in astronauts during standing postflight. The head-down tilt (HDT) rat model with "unloaded" hindlimbs has been extensively studied because some of the observed responses mimic observations made during exposure to microgravity. Angiotensin-(1-7) is a biologically active component of the renin-angiotensin system that acts to oppose the pressor and proliferative actions of Angiotensin II. It produces a hypotensive response by either stimulating production of vasodilator prostaglandins (i.e., prostacyclin), increasing nitric oxide or both. In the present study, we have evaluated the role of a specific inhibitor of Ang-(1-7), D-Ala7-Ang-(1-7)[A-779], as a countermeasure against post-suspension hypotension.

Hindlimb Suspension↗

Spaceflight Sensorimotor Analogs: Simulating Acute and Adaptive Effects

Adaptive changes in sensorimotor function during spaceflight are reflected by spatial disorientation, motion sickness, gaze destabilization and decrements in balance, locomotion and eye-hand coordination that occur during and following transitions between different gravitational states. The purpose of this study was to conduct a meta-synthesis of data from spaceflight analogs to evaluate their effectiveness in simulating adaptive changes in sensorimotor function. METHODS. The analogs under review were categorized as either acute analogs used to simulate performance decrements accompanied with transient changes, or adaptive analogs used to drive sensorimotor learning to altered sensory feedback. The effectiveness of each analog was evaluated in terms of mechanisms of action, magnitude and time course of observed deficits compared to spaceflight data, and the effects of amplitude and exposure duration. RESULTS. Parabolic flight has been used extensively to examine effects of acute variation in gravitational loads, ranging from hypergravity to microgravity. More recently, galvanic vestibular stimulation has been used to elicit acute postural, locomotor and gaze dysfunction by disrupting vestibular afferents. Patient populations, e.g., with bilateral vestibular loss or cerebellar dysfunction, have been proposed to model acute sensorimotor dysfunction. Early research sponsored by NASA involved living onboard rotating rooms, which appeared to approximate the time course of adaptation and post-exposure recovery observed in astronauts following spaceflight. Exposure to different bed-rest paradigms (6 deg head down, dry immersion) result in similar motor deficits to that observed following spaceflight. Shorter adaptive analogs have incorporated virtual reality environments, visual distortion paradigms, exposure to conflicting tilt-translation cues, and exposure to 3Gx centrifugation. As with spaceflight, there is considerable variability in responses to most of the analogs reviewed. DISCUSSION. A true ground-based flight analog for sensorimotor function is not feasible. A combination of flight analogs; however, can be used to selectively mimic different aspects of the spaceflight-induced sensorimotor performance decrements.

Taylor, Laura C.↗