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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.

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At least 937 records · Page 52
All sourcesNASA NTRSDOE OSTI
NASA NTRS2022

Co-leveraging Scientific Advances in Space Biology and Astrobiology Towards Achieving NASA’s Life Science Objectives

Executive Summary: Distinct lines of scientific inquiry drives the separation of NASA’s fundamental life science research into Space Biology and Astrobiology. This division developed as a way to place life scientists alongside experts in the physical constraints that define the acclimation, adaptation and evolution of biology systems relevant to their respective subjects. For astrobiology, integration with disciplines such as geology, geochemistry, astronomy, planetary science, etc., enables a comprehensive assessment of the physical environment and its co-evolution with biological processes. Space Biology’s co-location with Physical Sciences places life science researchers adjacent to experts in the physical phenomena associated with microgravity and spaceflight, enabling an understanding of how the spaceflight environment affects biological systems. Despite this separation, aspects of both disciplines have converged on a similar, fundamental objective: to describe and understand the dynamics of complex living communities in the contexts of their physical environments. While the environmental systems and timescales are dramatically different, continuing to motivate the separation into distinct fields, similarities in the underlying objective present opportunities to find efficiencies, reduce overlap, and minimize duplication of effort. Space Biology and Astrobiology share a common need to understand microbial physiology in extreme environments – whether the ‘built’ spaceflight environment or the natural environments in which many astrobiology studies are conducted. In particular, open questions in each discipline require the development of quantitative frameworks, applicable at the ecosystem level, that support predictive capabilities for environments where observations are sparse. Additionally, both disciplines have a need to prepare, detect, and analyze the (potential) biological signal in complex samples-often in a completely autonomous fashion. The next decade will see NASA Space Biology moving to understand and describe the effects of the beyond low-earth orbit (BLEO) spaceflight environment on living systems. This new direction will dramatically reduce the opportunities for ground-based analysis of space-flown samples, driving space biology investigations towards fully autonomous experiments and missions. At the same time, astrobiology life detection missions aimed at detecting biosignatures on Mars and icy moons in the outer solar system could benefit from fully automated sample processing and analysis. There are opportunities to leverage instrument and method development between both disciplines within the context of these BLEO missions.

Astrobiology↗
NASA NTRS2021

The Chain-link Actuator: Exploiting the Bending Stiffness of McKibben Artificial Muscles to Achieve Larger Contraction Ratios

McKibben artificial muscles, comprised of an ex-pandable bladder wrapped in a double-helix-braided sheath,have the ability to generate forces without restricting motion tooccur exclusively along the direction of actuation. This makesthem attractive for a variety of applications including soft,wearable, and biomimetic robots. Despite their advantages, thetheoretical maximum contraction ratio of McKibben muscles isonly 36.3%, which restricts the range of motion of the systemsthey actuate. This work introduces a novel ‘chain-link actuator’that exploits the bending stiffness of McKibben muscles toachieve contraction ratios of more than 50%. A static modelthat captures the relationship between pressure, displacement,and force is presented and validated on several real chain-linkactuator systems.

Daniel Bruder↗
NASA NTRSDate not supplied

Humans are Capable of Achieving Sufficient Sleep in Microgravity

Studies consistently find that humans average approximately six hours of sleep per night in space, which is less than they sleep on Earth. Consensus recommendations suggest that humans need at least seven hours of sleep per night for appropriate functioning. Such short sleep duration has been associated with reduced alertness and performance in space. It is unclear whether this sleep loss is related to modifiable factors, such as irregular scheduling, poor sleep environment, and excessive workload or due to features of spaceflight that alter physiology (e.g., microgravity). Recent missions have afforded crew better, more stable sleep and work schedules, and an improved sleep environment, including private, dark, and quiet crew quarters. Hence, the evaluation of sleep under these conditions should provide insight into the causes of sleep deficiency observed in space thus far.

fatigue↗
NASA NTRSDate not supplied

Experimental Capabilities and Achievements of the Space Environment Dynamometer (SED)

The Space Environment Dynamometer (SED) chamber was designed to conduct research in cryobotics; an area of study that focuses on robotic systems and rotating machinery operating in extreme cold environments including Earth, low Earth orbit, Mars, Moon, asteroids, Solar orbit, planetary orbit, or those encountered during travel among these destinations. The test chamber incorporates a modular dynamometer, consisting of a variety of brakes, torque sensors and motors to be easily interchanged between tests. Each test employs a unique test profile that incorporates different setpoints of applied torques and velocities for a given period or number of rev- olutions. The modularity of the dynamometer setup allows for any combination of motor, gearbox to be tested. This chamber is one of a kind and resides at the Swamp Works facility within the Granular Mechanics and Regolith Operations laboratory (GMRO) at NASA Kennedy Space Center. Other cold chambers exist, however they are project specific and do not simultaneously output real time torque, temperature and efficiency data. The modularity of this extreme cold environment test chamber, coupled with the custom software and instrumentation, makes it one of a kind. The chamber is capable of stabilizing cryogenic temperatures and pressures to commensurate moon environments. Tests have successfully been conducted on motors and gearboxes for various cryogenic temperature set points, torques, and angular velocities. Relevant internal temperatures of the test article and chamber were recorded using a variety of temperature sensors. The temperature setpoints, on the motors and gearboxes tested, were stabilized by using PID gain scheduling of the PWM signal for the various heaters. The heat removal for the motor was provided by creating a thermally conductive path from a cryohead directly to the test article using copper straps. A variety of strainwave gears (SWGs), also known as Harmonic drives, planetary gear systems and DC motor actuator configurations have been tested in the chamber. The experiments performed were for various projects including Bulk Metallic Glass Gears (BMGG), Volatiles Investigating Polar Exploration Rover (VIPER), In-Situ Resource Utilization Pilot Excavator (IPEX) . Various upgrades have been made to the extreme cold environment test chamber for the use of cryobotic research. These upgrades greatly increased the autonomous capabilities of the test set up by providing redundancies in the hardware and software. The redundancies were primarily added to protect the integrity of the cryohead. A new strapping and insulation method was performed to create the thermal conductive path from the actuators to the cryohead. The software was upgraded to include temperature setpoint control, further increasing the autonomous capabilities of the test. This paper goes into detail regarding the upgrades made to the extreme cold environment test chamber, as well as highlights the results from a COLDArm acceptance test.

Casey J. Clark↗
NASA NTRS2020

Continuity of A Global, Satellite-Based Terrestrial Primary Productivity Dataset in the VIIRS Era Achieved With Model-Data Fusion

The NASA Terra and Aqua satellites have been successfully operating for over two decades and have far exceeded their original 5‐year design life. However, the era of NASA’s Earth Observing System (EOS) may be coming to a close as early as 2023. We conducted a comprehensive calibration and validation of the MODIS MOD17 product [1,2] and the potential for continuity of multi‐decadal ecosystem gross primary productivity (GPP) and annual net primary productivity (NPP), using data from the Visible Infrared Imaging Radiometer Suite (VIIRS) sensors aboard Suomi NPP and NOAA‐20. We combined an 18‐year record of eddy covariance flux tower measurements with hundreds of field measurements of NPP from the Oak Ridge National Laboratories Multi‐Biome collection to benchmark MODIS MOD17 Collection 6.1 (C61) and to develop the first terrestrial productivity estimates from VIIRS. Plant traits from the literature and the global TRY database [3,4] provide strong priors for identifying model parameters in a Bayesian model‐data fusion. As MODIS‐like observations are still needed for global environmental applications, the new VIIRS VNP17 product has the potential to extend these continuous estimates of global, terrestrial primary productivity beyond 2030.

K. Arthur Endsley↗
NASA NTRSDate not supplied

Achieving Solar Pressure Equilibrium Attitude using Solar Array Feathering

Many competing requirements such as communication margin, thermal mitigation, and power generation may drive a specific flight attitude. However, a solar pressure equilibrium attitude (SPEA) is typically desired for a spacecraft in heliocentric space in order to minimize attitude maintenance. In this work, the benefits of solar array feathering in order to maintain specific and precise pointing requirements are quantified. A case study in which an asymmetrical spacecraft exploits a normally unstable flight attitude in concert with solar array feathering is explored in order to optimize power utilization while still minimizing attitude maintenance.

Benjamin Asher↗