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NASA NTRS2002

NASA Marshall Engineering Thermosphere Model

This Technical Memorandum describes the NASA Marshall Engineering Thermosphere Model-Version 2.0 (MET-V 2.0) and contains an explanation on the use of the computer program along with an example of the MET-V 2.0 model products. The MET-V 2.0 provides an update to the 1988 version of the model. It provides information on the total mass density, temperature, and individual species number densities for any altitude between 90 and 2,500 km as a function of latitude, longitude, time, and solar and geomagnetic activity. A description is given for use of estimated future 13-mo smoothed solar flux and geomagnetic index values as input to the model. Address technical questions on the MET-V 2.0 and associated computer program to Jerry K. Owens, Spaceflight Experiments Group, Marshall Space Flight Center, Huntsville, AL 35812 (256-961-7576; e-mail Jerry.Owens@msfc.nasa.gov).

Owens, J. K.↗

NASA NTRS2002

Microgravity Investigation of Crew Reactions in 0-G (MICR0-G): Ground-Based Development Effort

This report describes the technology development of an advanced load sensor ground-based prototype and details the preliminary tests in microgravity during parabolic flights. The research effort is entitled, the Microgravity Investigation and Crew Reactions in 0-G (MICR0-G), a ground-based research effort funded by the National Aeronautics and Space Administration (NASA). The MICR0-G project was a follow-on to the Enhanced Dynamic Load Sensors (EDLS) spaceflight experiment flown on the Russian Space Station Mir. The technology development of the advanced load sensor prototype has been carried out by the Massachusetts Institute of Technology (MIT), with collaboration from Politecnico di Milano University and the Italian Space Agency (ASI). The key hardware of the advanced sensor prototype is a set of two types of load sensors - a hand-hold and foot restraints - similar in appearance to the mobility aids found in the Space Shuttle orbiter to assist the crew in moving inside the spacecraft, but able to measure the applied forces and moments about the x-, y-, and z- axes. The aim of Chapter 1 is to give a brief overview of the report contents. The first section summarizes the previous research efforts on astronaut-induced loads in microgravity. The second section provides information on the MICR0-G research project and the technology development work conducted at MIT. Section 1.3 details the motivation for designing a new generation of load sensors and describes the main enhancements and contributions of the MICR0-G advanced load sensors system compared to the EDLS system. Finally, the last section presents the outline of the report.

Newman, Dava J.↗

NASA NTRS2003

Ribbon Synaptic Plasticity in Gravity Sensors of Rats Flown on Neurolab

Previous spaceflight experiments (Space Life Sciences-1 and -2 (SLS-1 and SLS-2)) first demonstrated the extraordinary ability of gravity sensor hair cells to change the number, kind, and distribution of connections (synapses) they make to other cells while in weightlessness. The number of synapses in hair cells in one part of the inner ear (the utricle) was markedly elevated on flight day 13 (FD13) of SLS-2. Unanswered questions, however, were whether these increases in synapses occur rapidly and whether they remain stable in weightlessness. The answers have implications for long-duration human space travel. If gravity sensors can adapt quickly, crews may be able to move easily between different gravity levels, since the sensors will adapt rapidly to weightlessness on the spacecraft and then back to Earth's gravity when the mission ends. This ability to adapt is also important for recovery from balance disorders. To further our understanding of this adaptive potential (a property called neuronal synaptic plasticity), the present Neurolab research was undertaken. Our experiment examined whether: (a) increases in synapses would remain stable throughout the flight, (b) changes in the number of synapses were uniform across different portions of the gravity sensors (the utricle and saccule), and (c) synaptic changes were similar for the different types of hair cells (Type I and Type II). Utricular and saccular maculae (the gravity-sensing portions of the inner ear) were collected in flight from rats on FD2 and FD14. Samples were also collected from control rats on the ground. Tissues were prepared for ultrastructural study. Hair cells and their ribbon synapses were examined in a transmission electron microscope. Synapses were counted in all hair cells in 50 consecutive sections that crossed the striolar zone. Results indicate that utricular hair cell synapses initially increased significantly in number in both types of hair cells by FD2. Counts declined by FD14, but the mean number of synapses in utricular Type II cells remained significantly higher than in the ground control rats. For saccular samples, synaptic number in Type I and Type II cells declined on FD2, but returned to near-baseline values by FD14. These findings indicate that: (a) synaptic plasticity occurs rapidly in weightlessness, and (b) synaptic changes are not identical for the two types of hair cells or for the two maculae.

Ross, Muriel D.↗

NASA NTRS2001

L-NAME, a nitric oxide synthase inhibitor, as a potential countermeasure to post-suspension hypotension in rats

A large number of astronauts returning from spaceflight experience orthostatic hypotension. This hypotension may be due to overproduction of vasodilatory mediators, such as nitric oxide (NO) and prostaglandins. To evaluate the role of the NO synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME) as a countermeasure against the post-suspension reduction in mean arterial pressure (MAP), we assessed the cardiovascular responses and vascular reactivity to 7-day 30 degrees tail-suspension and a subsequent 6 hr post-suspension period in conscious rats. After a pre-suspension reading, direct MAP and heart rate (HR) were measured daily and every 2 hrs post-suspension. The NO synthase inhibitor L-NAME (20 mg/kg, i.v.), or saline, were administered after the 7th day reading prior to release from suspension and at 2 and 4 hrs post-suspension. At 6 hrs post-suspension, vascular reactivity was assessed. While MAP did not change during the suspension period, it was reduced post-suspension. Heart rate was not significantly altered. L-NAME administration reversed the post-suspension reduction in MAP. In addition, the baroreflex sensitivity for heart rate was modified by L-NAME. Thus, the post-suspension reduction in MAP may be due to overproduction of NO and altered baroreflex activity.

NASA Discipline Cardiopulmonary↗

NASA NTRS2001

Decreased non-MHC-restricted (CD56+) killer cell cytotoxicity after spaceflight

Cytotoxic activity of non-major histocompatibility complex-restricted (CD56+) (NMHC) killer cells and cell surface marker expression of peripheral blood mononuclear cells were determined before and after spaceflight. Ten astronauts (9 men, 1 woman) from two space shuttle missions (9- and 10-day duration) participated in the study. Blood samples were collected 10 days before launch, within 3 h after landing, and 3 days after landing. All peripheral blood mononuclear cell preparations were cryopreserved and analyzed simultaneously in a 4-h cytotoxicity (51)Cr release assay using K562 target cells. NMHC killer cell lytic activity was normalized per 1,000 CD56+ cells. When all 10 subjects were considered as one study group, NMHC killer cell numbers did not change significantly during the three sampling periods, but at landing lytic activity had decreased by approximately 40% (P < 0.05) from preflight values. Nine of ten astronauts had decreased lytic activity immediately after flight. NMHC killer cell cytotoxicity of only three astronauts returned toward preflight values by 3 days after landing. Consistent with decreased NMHC killer cell cytotoxicity, urinary cortisol significantly increased after landing compared with preflight levels. Plasma cortisol and ACTH levels at landing were not significantly different from preflight values. No correlation of changes in NMHC killer cell function or hormone levels with factors such as age, gender, mission, or spaceflight experience was found. After landing, expression of the major lymphocyte surface markers (CD3, CD4, CD8, CD14, CD16, CD56), as determined by flow cytometric analysis, did not show any consistent changes from measurements made before flight.

NASA Center JSC↗

NASA NTRS1998

Gravitropism and development of wild-type and starch-deficient mutants of Arabidopsis during spaceflight

The "starch-statolith" hypothesis has been used by plant physiologists to explain the gravity perception mechanism in higher plants. In order to help resolve some of the controversy associated with ground-based research that has supported this theory, we performed a spaceflight experiment during the January 1997 mission of the Space Shuttle STS-81. Seedlings of wild-type (WT) Arabidopsis, two reduced-starch strains, and a starchless mutant were grown in microgravity and then given a gravity stimulus on a centrifuge. In terms of development in space, germination was greater than 90% for seeds in microgravity, and flight seedlings were smaller (60% in total length) compared to control plants grown on the ground and to control plants on a rotating clinostat. Seedlings grown in space had two structural features that distinguished them from the controls: a greater density of root hairs and an anomalous hypocotyl hook structure. However, the slower growth and morphological changes observed in the flight seedlings may be due to the effects of ethylene present in the spacecraft. Nevertheless, during the flight hypocotyls of WT seedlings responded to a unilateral 60 min stimulus provided by a 1-g centrifuge while those of the starch-deficient strains did not. Thus the strain with the greatest amount of starch responded to the stimulus given in flight and therefore, these data support the starch-statolith model for gravity sensing.

short duration↗

NASA NTRS1996

Effect of a hypergravity environment on cortical bone elasticity in rats

There is considerable interest in determining whether hypergravity can be used as a countermeasure for microgravity-induced bone loss. This study was conducted on 20 immature male rats in order to investigate possible elastic adaptations of cortical bone in rapidly growing rats exposed to chronic hypergravity. Ten rats were continuously centrifuged for 14 days at twice gravitational acceleration (2G) on a 12.75 foot radius centrifuge and 10 rats concurrently acted as stationary controls. The effect of hypergravity on the elastic characteristics of cortical bone was quantified via ultrasonic wave propagation. Propagation velocities of longitudinal and shear waves were measured through cubic cortical specimens from the posterior femoral diaphyses. Density was measured with an Archimedes' technique. The orthotropic elastic properties were calculated and used to compare the difference between groups. Results showed an average increase in both the Young's moduli (Eii, + 2.2%) and shear moduli (Gij, + 4.3%) with a statistically significant increase only in G12 (+15.7%, P = 0.046). The ratio of transverse to axial strain (Poisson's ratio, nuij) demonstrated statistically significant changes in nu12, nu21, nu13, and nu31 (P < 0.05). These findings suggest that although slight elastic changes were incurred via a hypergravity environment, the treatment level or duration in this study do not dramatically perturb the normal elastic behavior of cortical bone and that dramatic biomechanical differences noted in previous studies were due more to structural changes than material elasticity changes. Hypergravity applied post facto to a microgravity environment would offer further illucidation of this method as treatment for a degenerative spaceflight experience.

Non-NASA Center↗

NASA NTRS2006

Deep Space Test Bed for Radiation Studies

A key factor affecting the technical feasibility and cost of missions to Mars or the Moon is the need to protect the crew from ionizing radiation in space. Some analyses indicate that large amounts of spacecraft shielding may be necessary for crew safety. The shielding requirements are driven by the need to protect the crew from Galactic cosmic rays (GCR). Recent research activities aimed at enabling manned exploration have included shielding materials studies. A major goal of this research is to develop accurate radiation transport codes to calculate the shielding effectiveness of materials and to develop effective shielding strategies for spacecraft design. Validation of these models and calculations must be addressed in a relevant radiation environment to assure their technical readiness and accuracy. Test data obtained in the deep space radiation environment can provide definitive benchmarks and yield uncertainty estimates of the radiation transport codes. The two approaches presently used for code validation are ground based testing at particle accelerators and flight tests in high-inclination low-earth orbits provided by the shuttle, free-flyer platforms, or polar-orbiting satellites. These approaches have limitations in addressing all the radiation-shielding issues of deep space missions in both technical and practical areas. An approach based on long duration high altitude polar balloon flights provides exposure to the galactic cosmic ray composition and spectra encountered in deep space at a lower cost and with easier and more frequent access than afforded with spaceflight opportunities. This approach also results in shorter development times than spaceflight experiments, which is important for addressing changing program goals and requirements.

Adams, James H.↗

NASA NTRS2007

Risk Assessment Challenges in the Ares I Upper Stage

NASA Marshall Space Flight Center (MSFC) is currently at work developing hardware and systems for the Ares I rocket that will send future astronauts into orbit. Built on cutting-edge launch technologies, evolved powerful Apollo and Space Shuttle propulsion elements, and decades of NASA spaceflight experience, Ares I is the essential core of a safe, reliable, cost-effective space transportation system -- one that will carry crewed missions back to the moon, on to Mars and out into the solar system. Ares I is an in-line, two-stage rocket configuration topped by the Orion crew vehicle and its launch abort system. In addition to the vehicle's primary mission -carrying crews of four to six astronauts to Earth orbit --Ares I may also use its 25-ton payload capacity to deliver resources and supplies to the International Space Station, or to "park" payloads in orbit for retrieval by other spacecraft bound for the moon or other destinations. Crew transportation to the International Space Station is planned to begin no later than 2014. The first lunar excursion is scheduled for the 2020 timeframe. This paper presents the challenges in designing the Ares I upper stage for reliability and safety while minimizing weight and maximizing performance.

Stott, James E.↗

NASA NTRS2008

Reusability Studies for Ares I and Ares V Propulsion

With a mission to continue to support the goals of the International Space Station (ISS) and explore beyond Earth orbit, the United States National Aeronautics and Space Administration (NASA) is in the process of launching an entirely new space exploration initiative, the Constellation Program. Even as the Space Shuttle moves toward its final voyage, Constellation is building from nearly half a century of NASA spaceflight experience, and technological advances, including the legacy of Shuttle and earlier programs such as Apollo and the Saturn V rocket. Out of Constellation will come two new launch vehicles: the Ares I crew launch vehicle and the Ares V cargo launch vehicle. With the initial goal to seamlessly continue where the Space Shuttle leaves off, Ares will firstly service the Space Station. Ultimately, however, the intent is to push further: to establish an outpost on the Moon, and then to explore other destinations. With significant experience and a strong foundation in aerospace, NASA is now progressing toward the final design of the First Stage propulsion system for the Ares I. The new launch vehicle design will considerably increase safety and reliability, reduce the cost of accessing space, and provide a viable growth path for human space exploration. To achieve these goals, NASA is taking advantage of Space Shuttle hardware, safety, reliability, and experience. With efforts to minimize technical risk and life-cycle costs, the First Stage office is again pulling from NASA s strong legacy in aerospace exploration and development, most specifically the Space Shuttle Program. Trade studies have been conducted to evaluate life-cycle costs, expendability, and risk reduction. While many first stage features have already been determined, these trade studies are helping to resolve the operational requisites and configuration of the first stage element. This paper first presents an overview of the Ares missions and the genesis of the Ares vehicle design. It then looks at one of the most important trade studies to date, the "Ares I First Stage Expendability Trade Study." The purpose of this study was to determine the utility of flying the first stage as an expendable booster rather than making it reusable. To lower the study complexity, four operational scenarios (or cases) were defined. This assessment then included an evaluation of the development, reliability, performance, and transition impacts associated with an expendable solution. This paper looks at these scenarios from the perspectives of cost, reliability, and performance.

Williams, Thomas J.↗

NASA NTRS2009

Operations to Research: Communication of Lessons Learned

This presentation explores ways to build upon previous spaceflight experience and communicate this knowledge to prepare for future exploration. An operational approach is highlighted, focusing on selection and retention standards (disease screening and obtaining medical histories); pre-, in-, and post-flight monitoring (establishing degrees of bone loss, skeletal muscle loss, cardiovascular deconditioning, medical conditions, etc.); prevention, mitigation, or treatment (in-flight countermeasures); and, reconditioning, recovery, and reassignment (post-flight training regimen, return to pre-flight baseline and flight assignment). Experiences and lessons learned from the Apollo, Skylab, Shuttle, Shuttle-Mir, International Space Station, and Orion missions are outlined.

Fogarty, Jennifer↗

NASA NTRS2009

The Ares Launch Vehicles: Critical Capabilities for America's Continued Leadership in Space

The Constellation Program renews the nation's commitment to human space exploration a) Access to ISS. b) Human explorers to the Moon and beyond. c) Large telescopes and other hardware to LEO . Hardware is being built today. Development made easier by applying lessons learned from 50 years of spaceflight experience. Ares V heavy-lift capability will be a strategic asset for the nation. Constellation provides a means for world leadership through inspiration and strategic capability.

Cook, Stephen A.↗

NASA NTRS2010

Approach to In Situ Component Level Electronics Assembly Repair (CLEAR) for Constellation

Maintenance resupply is a significant issue for long duration space missions. Currently, the International Space Station (ISS) approaches maintenance primarily around replaceable modules called Orbital Replacement Units (ORU). While swapping out ORUs has served the ISS well keeping crew time for maintenance to a minimum, this approach assumes a substantial logistics capacity to provide replacement ORUs and return ORUs to Earth for repair. The ORUs used for ISS require relatively large blocks of replacement hardware even though the actual failed component may be several orders of magnitude smaller. The Component Level Electronics Assembly Repair (CLEAR) task was created to explore electronics repair down to the component level for future space missions. From 2006 to 2009, CLEAR was an activity under the Supportability project of the Exploration Technology Development Program. This paper describes the activities of CLEAR including making a case for component-level electronics repair, examination of current terrestrial repair hardware, and potential repair needs. Based on those needs, the CLEAR team proposes an architecture for an in-situ repair capability aboard a spacecraft or habitat. Additionally, this paper discusses recent progress toward developing in-space repair capabilities--including two spaceflight experiments-- and presents technology concepts which could help enable or benefit the same.

Struk, Peter M.↗

NASA NTRS2015

The Asteroid Redirect Mission (ARM)

The National Aeronautics and Space Administration (NASA) is developing a robotic mission to visit a large near-Earth asteroid (NEA), collect a multi-ton boulder from its surface, and redirect it into a stable orbit around the Moon. Once returned to cislunar space in the mid-2020s, astronauts will explore the boulder and return to Earth with samples. This Asteroid Redirect Mission (ARM) is part of NASA's plan to advance the technologies, capabilities, and spaceflight experience needed for a human mission to the Martian system in the 2030s. Subsequent human and robotic missions to the asteroidal material would also be facilitated by its return to cislunar space. Although ARM is primarily a capability demonstration mission (i.e., technologies and associated operations), there exist significant opportunities to advance our knowledge of small bodies in the synergistic areas of science, planetary defense, asteroidal resources and in-situ resource utilization (ISRU), and capability and technology demonstrations. In order to maximize the knowledge return from the mission, NASA is organizing an ARM Investigation Team, which is being preceded by the Formulation Assessment and Support Team. These teams will be comprised of scientists, technologists, and other qualified and interested individuals to help plan the implementation and execution of ARM. An overview of robotic and crewed segments of ARM, including the mission requirements, NEA targets, and mission operations, will be provided along with a discussion of the potential opportunities associated with the mission.

Abell, Paul↗

NASA NTRS2016

Initial Incidence of White Matter Hyperintensities on MRI in Astronauts

Introduction: Previous literature has described the increase in white matter hyperintensity (WMH) burden associated with hypobaric exposure in the U-2 and altitude chamber operating personnel. Although astronauts have similar hypobaric exposure pressures to the U2 pilot population, astronauts have far fewer exposures and each exposure would be associated with a much lower level of decompression stress due to rigorous countermeasures to prevent decompression sickness. Therefore, we postulated that the WMH burden in the astronaut population would be less than in U2 pilots. Methods: Twenty-one post-flight de-identified astronaut MRIs (5 mm slice thickness FLAIR sequences) were evaluated for WMH count and volume. The only additional data provided was an age range of the astronauts (43-57) and if they had ever performed an EVA (13 yes, 8 no). Results: WMH count in these 21 astronaut MRI was 21.0 +/- 24.8 (mean+/- SD) and volume was 0.382 +/- 0.602 ml, which was significantly higher than previously published results for the U2 pilots. No significant differences between EVA and no EVA groups existed. Age range of astronaut population is not directly comparable to the U2 population. Discussion: With significantly less frequent (sometimes none) and less stressful hypobaric exposures, yet a much higher incidence of increased WMH, this indicates the possibility of additional mechanisms beyond hypobaric exposure. This increase unlikely to be attributable just to the differences in age between astronauts and U2 pilots. Forward work includes continuing review of post-flight MRI and evaluation of pre to post flight MRI changes if available. Data mining for potential WMH risk factors includes collection of age, sex, spaceflight experience, EVA hours, other hypobaric exposures, hyperoxic exposures, radiation, high performance aircraft experience and past medical history. Finally, neurocognitive and vision/eye results will be evaluated for any evidence of impairment linked to increased WMH.

Norcross, Jason↗

NASA NTRS2016

Evaluation of an Impedance Threshold Device as a VIIP Countermeasure

Visual Impairment /Intracranial Pressure (VIIP) is a top human spaceflight risk for which NASA does not currently have a proven mitigation strategy. Thigh cuffs (Braslets) and lower body negative pressure (LBNP; Chibis) devices have been or are currently being evaluated as a means to reduce VIIP signs and symptoms, but these methods alone may not provide sufficient relief of cephalic venous congestion and VIIP symptoms. Additionally, current LBNP devices are too large and cumbersome for their systematic use as a countermeasure. Therefore, a novel approach is needed that is easy to implement and provides specific relief of symptoms. This investigation will evaluate an impedance threshold device (ITD) as a VIIP countermeasure. The ITD works by providing up to 7 cm H2O (approximately 5 mmHg) resistance to inspiratory air flow, effectively turning the thorax into a vacuum pump upon each inhalation which lowers the intrathoracic pressure (ITP) and facilitates venous return to the heart. The ITD is FDA-approved and was developed to augment venous return to the central circulation and increase cardiac output during cardiopulmonary resuscitation (CPR) and in patients with hypotension. While the effect of ITD on CPR survival outcomes is controversial, the ITD's ability to lower ITP with a concomitant decrease in intracranial pressure (ICP) is well documented. A similar concept that creates negative ITP during exhalation (intrathoracic pressure regulator; ITPR) decreased ICP in 16 of 20 patients with elevated ICP in a hospital pilot study. ITP and central venous pressure (CVP) have been shown to decrease in microgravity however ITP drops more than CVP, indicating an increased transmural CVP. This could explain the paradoxical distention of jugular veins (JV) in microgravity despite lower absolute CVP and also suggests that JV transmural pressure is not dramatically elevated. Use of an ITD may lower JV pressure enough to remove or relieve cephalic venous congestion. During spaceflight experiments with Braslet thigh cuffs and modified (open-glottis) Mueller maneuvers, Braslets alone reduced cardiac preload but only reduced the internal JV (IJV) cross sectional area by 23%. The addition of Mueller maneuvers resulted in an IJV area reduction of 48%. This project will test if ITD essentially applies a Mueller maneuver with added negative ITP in every respiratory cycle, acting to: 1) reduce venous congestion in the neck and 2) potentially lower ICP. The expected mechanism of action is that in microgravity (or an analog) blood is relocated toward the heart from vasculature in the head and neck. Once validated, the ITD would be an exceptionally easy countermeasure to deploy and test on the ISS. Dosage could be altered though 1) duration of application and 2) inspiratory resistance set point. Effects could be additionally enhanced through co-application with other countermeasures such as thigh cuffs or LBNP.

Ebert, D.↗

NASA NTRS2016

Evaluation of an Impedance Threshold Device as a VIIP Countermeasure

Visual Impairment/Intracranial Pressure (VIIP) is a top human spaceflight risk for which NASA does not currently have a proven mitigation strategy. Thigh cuffs (Braslets) and lower body negative pressure (LBNP; Chibis) devices have been or are currently being evaluated as a means to reduce VIIP signs and symptoms, but these methods alone may not provide sufficient relief of cephalic venous congestion and VIIP symptoms. Additionally, current LBNP devices are too large and cumbersome for their systematic use as a countermeasure. Therefore, a novel approach is needed that is easy to implement and provides specific relief of symptoms. This investigation will evaluate an impedance threshold device (ITD) as a VIIP countermeasure. The ITD works by providing up to 7 cm H2O (approximately 5 mmHg) resistance to inspiratory air flow, effectively turning the thorax into a vacuum pump upon each inhalation which lowers the intrathoracic pressure (ITP) and facilitates venous return to the heart. The ITD is FDA-approved and was developed to augment venous return to the central circulation and increase cardiac output during cardiopulmonary resuscitation (CPR) and in patients with hypotension. While the effect of ITD on CPR survival outcomes is controversial, the ITD's ability to lower ITP with a concomitant decrease in intracranial pressure (ICP) is well documented. A similar concept that creates negative ITP during exhalation (intrathoracic pressure regulator; ITPR) decreased ICP in 16 of 20 patients with elevated ICP in a hospital pilot study. ITP and central venous pressure (CVP) have been shown to decrease in microgravity however ITP drops more than CVP, indicating an increased transmural CVP. This could explain the paradoxical distention of jugular veins (JV) in microgravity despite lower absolute CVP and also suggests that JV transmural pressure is not dramatically elevated. Use of an ITD may lower JV pressure enough to remove or relieve cephalic venous congestion. During spaceflight experiments with Braslet thigh cuffs and modified (open-glottis) Mueller maneuvers, Braslets alone reduced cardiac preload but only reduced the internal JV (IJV) cross sectional area by 23%. The addition of Mueller maneuvers resulted in an IJV area reduction of 48%. This project will test if ITD essentially applies a Mueller maneuver with added negative ITP in every respiratory cycle, acting to: 1) reduce venous congestion in the neck and 2) potentially lower ICP. The expected mechanism of action is that in microgravity (or an analog) blood is relocated toward the heart from vasculature in the head and neck. Once validated, the ITD would be an exceptionally easy countermeasure to deploy and test on the ISS. Dosage could be altered though 1) duration of application and 2) inspiratory resistance set point. Effects could be additionally enhanced through co-application with other countermeasures such as thigh cuffs or LBNP.

Ebert, Douglas↗

NASA NTRS2016

Conceptual Drivers for an Exploration Medical System

Interplanetary spaceflight provides unique challenges that have not been encountered in prior spaceflight experience. Extended distance and timeframes introduce new challenges such as an inability to resupply medications and consumables, inability to evacuate injured or ill crew, and communication delays that introduce a requirement for some level of autonomous medical capability. Because of these challenges the approaches used in prior programs have limited application to a proposed three year Mars mission. This paper proposes a paradigm shift in the approach to medical risk mitigation for crew health and mission objectives threatened by inadequate medical capabilities in the setting of severely limited resources. A conceptual approach is outlined to derive medical system and vehicle needs from an integrated vision of how medical care will be provided within this new paradigm. Using NASA Design Reference Missions this process assesses each mission phase to deconstruct medical needs at any point during a mission. Two operational categories are proposed, nominal operations (pre-planned activities) and contingency operations (medical conditions requiring evaluation) that meld clinical needs and research needs into a single system. These definitions are used to derive a task level analysis to support quantifiable studies into a medical capabilities trade. This trade allows system design to proceed from both a mission centric and ethics-based approach to medical limitations in an exploration class mission.

Antonsen, E.↗