550909 research outputs found
Sort by
Strategic Implications of Phobos as a Staging Point for Mars Surface Missions
Get PDFAs human exploration endeavors begin to set sights beyond low Earth orbit to the surface of the Moon, exploration of the surface of Mars continues to serve as the horizon destination to help focus development and research efforts. One Mars exploration strategy often discussed is the notion of utilizing the moons of Mars, namely Phobos, as an exploration destination prior to Mars surface missions. The premise behind this is that staging missions from Mars moons as well as exploring the moons themselves would be less costly and risky. However, understanding potential advantages of Phobos staging and exploration must be done in the context of the overall end-to-end Mars surface exploration needs, goals, objectives, campaign approach, and systems required. This paper examines the strategic implications of utilizing the moons of Mars as a potential location for exploration of Mars. Operational concepts utilizing both Phobos and Mars orbital strategies will be examined to understand the architectural impacts of this staging strategy. The strategic implications of each operational concept are assessed to determine the overall key challenges and strategic links to other exploration destinations. Results from this analysis indicate that, if the objective is to conduct Mars surface missions, utilizing Phobos as an exploration destination adds little benefit toward the goal of exploration of Mars
We Should Search for Life in Mars N. Polar Ground Ice
Get PDFThe 2008 Phoenix Mars lander mission sampled ground ice at 68N latitude. Mission results, considered along with climate modeling studies, suggest that the site is habitable for life during high obliquity periods. The Icebreaker mission has been proposed to the NASA Discovery program to search for biosignatures produced during habitable periods. This paper explores its rationale and approach
Biodegradation of Yukon River Delta Dissolved Organic Matter Is Marginally Enhanced by Nutrient Enrichment
Get PDFNo abstract availabl
Heliophysics: Prediction of Radiation Doses Received During Airplane Flights
Get PDFNo abstract availabl
Gene and MicroRNA Expression Profile Changes in ISS Crewmembers Blood Samples
Get PDFIn space, living organisms are exposed to multiple stress factors including microgravity and space radiation. For humans, these harmful environmental factors have been known to cause negative health impacts such as immune dysfunction. Understanding the mechanisms by which spaceflight impacts human health at the molecular level is critical not only for accurately assessing the risks associated with spaceflight, but also for developing effective countermeasures. This study is part of the Functional Immune Project, intended to determine alterations in crewmember immunobiology before, during, and after spaceflight. It emphasizes the study of DNA damage in the ISS crewmembers peripheral blood mononuclear cells (PBMCs), expression patterns of damage-response and inflammatory process genes, and changes in latent virus reactivation biomarkers
Neuro-vestibular Examination During and Following Spaceflight
Get PDFAdaptation to microgravity during spaceflight causes neurological disturbances that are either directly or indirectly mediated by the vestibular system. These disturbances could include space motion sickness, spatial disorientation, cognitive impairment, as well as changes in head-eye coordination, vestibulo-ocular reflex, and strategies for controlling posture and locomotion. It seems that otolith-mediated reflex gain adapts rapidly over time during spaceflight and after landing. However, animal studies have shown that structural modifications of the vestibular sensory apparatus develop during long-duration spaceflight. To date, no studies have characterized the severity of vestibular syndromes experienced by astronauts as a function of the duration of spaceflight, or whether the effects are caused by changes at the peripheral end organs, midbrain, cerebellum, or vestibular cortex
Use of Otoacousticemission Phase Change to Evaluate Countermeasures for Spaceflight-Associated Neuro-Ocular Syndrome
Get PDFSpaceflight-associated neuro-ocular syndrome (SANS) is a human spaceflight risk recognized by NASA. Elevated intracranial pressure (ICP) has been implicated as a root cause of many SANS signs and symptoms, yet there is no reliable noninvasive means of monitoring ICP. We have developed a noninvasive method of monitoring ICP change that exploits ear canal acoustic and otoacoustic emission (OAE) measurements. Changed ICP alters pressure in the inner ear, leading to changes in the tension and position of middle ear (ME) components; tension of these components determines the phase of the stimulus in the ear canal and the OAE response sound transmission back through the ME. The OAE method has been validated in several studies, including our own experiments as part of the NASA Fluid Shifts study. Systematic OAE phase changes demonstrating increased ME tension (an ICP indicator) are observed as posture is changed from seated to supine to head-down tilt (HDT). This effect can be substantially mitigated by lower body negative pressure (LBNP). The OAE technique has also been used on International Space Station (ISS) crewmembers, providing evidence that ICP in microgravity is similar to that seen on the ground in the supine position. The OAE method is also a rapid and noninvasive means of assessing the effectiveness of SANS countermeasures. Here we report results from two studies which used OAEs. In the most recent study (Venous Congestion Countermeasures - VCCM), three promising countermeasures [LBNP, an impedance threshold device (ITD), and veno-occlusive thigh cuffs (VTC)] were applied individually and in combination. In our previous ITD-only study, ITD was investigated for its ability to reduce ICP and cephalic venous congestion in supine and various HDT postures. Internal jugular vein (IJV) ultrasound showed a clear decongestive effect at all postures, however OAE data showed that ITD only caused a phase decrease (tension decrease) in HDT postures. In supine, ITD appeared to INCREASE tension. This paradox leads us to hypothesize that the OAE method is not accurately representing ICP changes with countermeasures (CM), which can alter ME tension through other means, such as ME pressure (MEP) changes. More generally, the exact mechanism for observed OAE response and stimulus phase shifts are not clearly understood, specifically with regard to the effects of MEP. The VCCM study examined the effects of externally-applied MEP on OAE recordings to document the relationship between these parameters. Analysis of these data provide new insights to these OAE mechanisms, in addition to results on CM effectiveness
Role of NASA's SeaBASS Repository for the Legacy of the EXPORTS Field Biogeochemical Measurements
Get PDFRole of NASA's SeaBASS repository for the legacy of the EXPORTS field biogeochemical measurements