Search NASA⌕ Search

SEARCH · Search NASA

Results for “Space Flight Environment”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
NASA NTRS2008

Development of the Lunar Environments Test System (LETS)

The lunar surface is an inhospitable environment to work in to say the least. The environment on the lunar surface is defined by intense ultraviolet radiation, solar wind radiation (primarily electrons and protons), electrically charged dust layers, and temperatures as low as -200 C. As NASA makes plans to send manned missions to the moon's surface, significant preparation must be undertaken to ensure that the materials and mechanical components used on those missions can survive in the harsh environment. The work presented will detail the development of the Lunar Environment Test System (LETS) at the Marshall Space Flight Center that will allow scientists and engineers the ability to test new materials, mechanical components, and proposed mission hardware in a representative lunar surface environment. The LETS encompasses all the environments of the lunar surface including vacuum, thermal extremes, vacuum ultraviolet radiation, and protons and electrons from the solar wind.

Vaughn, Jason A.↗
NASA NTRS2015

Results of Lunar Impact Observations During Geminid Meteor Shower Events

Meteoroids are natural particles with origins from comets, asteroids, and planets from within the solar system. On average, 33 metric tons (73,000 lb) of meteoroids hit Earth everyday with velocities ranging between 20 and 72 km/s. However, the vast majority of these meteoroids disintegrate in the atmosphere and never make it to the ground. The Moon also encounters the same meteoroid flux, but has no atmosphere to stop them from striking the surface. At such speeds even a small meteoroid has incredible energy. A meteoroid with a mass of only 5 kg can excavate a crater over 9 m across, hurling 75 metric tons (165,000 lb) of lunar soil and rock on ballistic trajectories above the lunar surface. Meteoroids with particle sizes as small as 100 micrometer (1 Microgram) can do considerable damage to spacecraft in Earth's orbit and beyond. Impacts can damage thermal protection systems, radiators, windows, and pressurized containers. Secondary effects might include partial penetration or pitting, local deformation, and surface degradation that can cause a failure upon reentry. The speed, mass, density, and flux of meteoroids are important factors for design considerations and mitigation during operations. Lunar operations (unmanned and manned) are also adversely affected by the meteoroid flux. Ejecta from meteoroid impacts is also part of the lunar environment and must be characterized. Understanding meteoroid fluxes and the associated risk of meteoroids impacting spacecraft traveling in and beyond Earth's orbit is the objective of the Meteoroid Environment Office (MEO) located at Marshall Space Flight Center (MSFC). One of the MEO's programs is meteoroid impact monitoring of the Moon. The large collecting area of the night side of the lunar disk provides statistically significant counts of meteoroids that can provide useful information about the flux of meteoroids in the hundreds of grams to kilograms size range. This information is not only important for characterizing the lunar environment associated with larger lunar impactors, but also provides statistical data for verification and improving meteoroid prediction models. Current meteoroid models indicate that the Moon is struck by a sporadic meteoroid with a mass greater than 1 kg over 260 times per year. This number is very uncertain since observations for objects in this mass range are few. Factors of several times, higher or lower, are easily possible. Meteor showers are also present to varying degrees at certain times of the year. The Earth experiences meteor showers when encountering the debris left behind by comets, which is also the case with 2 the Moon. During such times, the rate of shower meteoroids can greatly exceed that of the sporadic background rate for larger meteoroids. Looking for meteor shower impacts on the Moon at about the same time as they occur on Earth will yield important data that can be fed into meteor shower forecasting models, which can then be used to predict times of greater meteoroid hazard on the Moon. The Geminids are one such meteor shower of interest. The Geminids are a major meteor shower that occur in December with a peak intensity occurring usually during the 13th and 14th of the month and appearing to come from a radiant in the constellation Gemini. The Geminids are interesting in that the parent body of the debris stream is an asteroid, which along with the Quadrantids, are the only major meteor showers not originating from a comet. The Geminids parent body, 3200 Phaethon, is about 5 km in diameter and has an orbit that has a 22deg inclination which intersects the main asteroid belt and has a perihelion less than half of Mercury's perihelion distance. Thus, its orbit crosses those of Mars, Earth, Venus, and Mercury. The Geminid debris stream is by far the most massive as compared to the others. When the Earth passes through the stream in mid-December, a peak intensity of approx. equal 120 meteors per hour can be seen. Because of the Geminids' relatively large intensity and unique origin, it is important to monitor and gain information about the Geminids so as to improve their forecasts and understand their contribution to the meteoroid environment in Earth's orbit and at the Moon. It is the purpose of this Technical Memorandum (TM) to document two lunar observing periods coinciding with the Geminid meteor showers that occurred in 2006 and 2010.

Suggs, R. J.↗
NASA NTRS1986

Assessment of the efficacy of medical countermeasures in space flight

Changes in body fluids, electrolytes and muscle mass are manifestations of adaptation to space flight and readaptation to the 1-g environment. The purpose of this paper is to review the current knowledge of biomedical responses to short- and long-duration space missions and to assess the efficacy of countermeasures to 1-g deconditioning. Exercise protocols, fluid hydration, dietary and potential pharmacologic measures are evaluated, and directions for future research activities are recommended.

Nicogossian, A.↗
NASA NTRS1989

Assessment of the efficacy of medical countermeasures in space flight

Changes in body fluids, electrolytes, and muscle mass are manifestations of adaptation to space flight and readaptation to the 1-g environment. The purposes of this paper are to review the current knowledge of biomedical responses to short- and long-duration space missions and to assess the efficacy of countermeasures to 1-g conditioning. Exercise protocols, fluid hydration, dietary and potential pharmacologic measures are evaluated, and directions for future research activities are recommended.

Nicogossian, A. E.↗
NASA NTRS2009

Measurement and Characterization of Space Shuttle Solid Rocket Motor Plume Acoustics

Lift-off acoustic environments generated by the future Ares I launch vehicle are assessed by the NASA Marshall Space Flight Center (MSFC) acoustics team using several prediction tools. This acoustic environment is directly caused by the Ares I First Stage booster, powered by the five-segment Reusable Solid Rocket Motor (RSRMV). The RSRMV is a larger-thrust derivative design from the currently used Space Shuttle solid rocket motor, the Reusable Solid Rocket Motor (RSRM). Lift-off acoustics is an integral part of the composite launch vibration environment affecting the Ares launch vehicle and must be assessed to help generate hardware qualification levels and ensure structural integrity of the vehicle during launch and lift-off. Available prediction tools that use free field noise source spectrums as a starting point for generation of lift-off acoustic environments are described in the monograph NASA SP-8072: "Acoustic Loads Generated by the Propulsion System." This monograph uses a reference database for free field noise source spectrums which consist of subscale rocket motor firings, oriented in horizontal static configurations. The phrase "subscale" is appropriate, since the thrust levels of rockets in the reference database are orders of magnitude lower than the current design thrust for the Ares launch family. Thus, extrapolation is needed to extend the various reference curves to match Ares-scale acoustic levels. This extrapolation process yields a subsequent amount of uncertainty added upon the acoustic environment predictions. As the Ares launch vehicle design schedule progresses, it is important to take every opportunity to lower prediction uncertainty and subsequently increase prediction accuracy. Never before in NASA s history has plume acoustics been measured for large scale solid rocket motors. Approximately twice a year, the RSRM prime vendor, ATK Launch Systems, static fires an assembled RSRM motor in a horizontal configuration at their test facility in Utah. The remaining RSRM static firings will take place on elevated terrain, with the nozzle exit plume being mostly undeflected and the landscape allowing placement of microphones within direct line of sight to the exhaust plume. These measurements will help assess the current extrapolation process by direct comparison between subscale and full scale solid rocket motor data.

Kenny, Jeremy↗
NASA NTRS1977

Containerless processing of beryllium

Melting and solidification of a beryllium alloy containing 1.5% BeO by weight in the weightless environment of space has produced cast beryllium with a relatively uniform dispersion of BeO throughout. Examination of the cast material shows that it is coarse grained, although the BeO is not heavily agglomerated in the flight specimen. Ground based comparison experiments show extreme agglomeration and segregation of BeO, resulting in large zones which are practically free of the oxide. Several postulated hypotheses for the failure to grain refine the beryllium are formulated. These are: (1) spherodization of the BeO particles during specimen preparation and during the molten phase of the experiment; (2) loss of nucleation potency through aging in the molten phase; and (3) inability of BeO to act as a grain refiner for beryllium. Further investigation with non spherodized particles and shorter dwell times molten may delineate which of these hypotheses are valid. The results of this flight experiment indicate that the weightless environment of space is an important asset in conducting research to find grain refiners for beryllium and other metals for which cast dispersions of grain refining agents cannot be prepared terrestrially due to gravitationally driven settling and agglomeration.

Wouch, G.↗
NASA NTRSDate not supplied

Stochastic Verification by Analysis for Autonomous Systems Management Architecture (ASMA)

The Gateway Vehicle Systems Manager (VSM) is the top-level of a distributed, hierarchical software control system. VSM is data-driven and will make decisions related to mission, fault, resource management and vehicle control. These attributes combined with a high degree of autonomy make it susceptible to emergent behavior. In order to achieve the high level of confidence needed in this critical system, the VSM team has developed a multifaceted verification strategy employing traditional verification techniques, simulation, model checking, and runtime verification. Individual algorithms are verified using conventional testing and model checking using assume-guarantee contracts. A discrete event-based simulation approach is being developed to verify timelines. This presentation describes an enhancement to the verification approach using analysis to enhance system robustness by detecting and resolving the potential for emergent behavior. The verification by analysis employs a Software in the Loop (SITL) environment with real flight software executing on emulated processors, simulations of vehicle subsystems, flight dynamics, and human inputs. Since the possible input space and configuration data set are too large for exhaustive testing, a Monte Carlo approach is used to cover feasible scenarios, augmented with corner cases and known higher-risk scenarios. A key problem in using Monte Carlo-based system verification is evaluating test results to ensure that system behavior is correct. The presentation describes the approach the VSM team uses to monitor behavior for compliance with predetermined boundaries and to identify anomalous behavior for further analysis. This presentation describes the multi-level systems approach to verification, and the simulation-based layer that covers the feasible state space: 1. Overview of the Gateway VSM 2. Special challenges due to heterogeneous, hierarchical architecture 3. Modeling and simulation environment using flight software and system simulations 4. Developing input sets to ensure state-space coverage 5. Developing model and data configuration sets to ensure model coverage 6. Interpreting results without predetermined outcomes 7. Lessons learned and future work

Verification and Validation↗
NASA NTRS2017

Radiation Hardness Assurance (RHA): Challenges and New Considerations

Radiation Hardness Assurance (RHA) challenges associated with the use of commercial-off-the-shelf (COTS) components and emerging technologies are cause for risk acceptance in space flight missions. The RHA flow includes environment definition, hazard evaluation, requirements definition, evaluation of design, and design trades to accommodate the risk a project or program takes. The varied missions profiles and environments don't necessarily benefit from the same risk reduction efforts or cost reduction attempts. The level of effort within the RHA flow can be tailored to minimize risk based on the environment or design criticality.

Space Technology↗
NASA NTRS2012

Space Environmental Effects (SEE) Testing Capability: NASA/Marshall Space Flight Center

Understanding the effects of the space environment on materials and systems is fundamental and essential for mission success. If not properly understood and designed for, the space environment can lead to materials degradation, reduction of functional lifetime, and system failure. Ground based testing is critical in predicting performance NASA/MSFC's expertise and capabilities make up the most complete SEE testing capability available.

DeWittBurns, H.↗
NASA NTRS2014

Evolution and Implementation of the NASA Robotic Conjunction Assessment Risk Analysis Concept of Operations

Reacting to potential on-orbit collision risk in an operational environment requires timely and accurate communication and exchange of data, information, and analysis to ensure informed decision-making for safety of flight and responsible use of the shared space environment. To accomplish this mission, it is imperative that all stakeholders effectively manage resources: devoting necessary and potentially intensive resource commitment to responding to high-risk conjunction events and preventing unnecessary expenditure of resources on events of low collision risk. After 10 years of operational experience, the NASA Robotic Conjunction Assessment Risk Analysis (CARA) is modifying its Concept of Operations (CONOPS) to ensure this alignment of collision risk and resource management. This evolution manifests itself in the approach to characterizing, reporting, and refining of collision risk. Implementation of this updated CONOPS is expected to have a demonstrated improvement on the efficacy of JSpOC, CARA, and owner/operator resources.

operations↗
NASA NTRSDate not supplied

Durability of Passive Thermal Control Materials Exposed to Low Earth Orbit Environment

Spacecraft components for passive thermal control need to resist degradation in the space environment. The Materials on International Space Station Experiment (MISSE) 11th, 15th, and 16th flights and the Materials Exposure and Technology Innovation in Space (METIS) 1st and 2nd flights exposed a variety of materials to the low Earth orbital environment. Materials discussed in this presentation include chemical conversion coatings per MIL-DTL-5541, thermal control coatings, and thermal protection materials for high temperature applications. Space environmental and molecular contamination effects on optical properties are reviewed. Future MISSE and METIS experiments are discussed.

space environment↗
NASA NTRS2004

Frequency Weighted H2 Control Design for the Glovebox Integrated Microgravity Isolation Technology (g-LIMIT)

The acceleration environment on the International Space Station (ISS) exceeds the requirements of many microgravity experiments. The Glovebox Integrated Microgravity Isolation Technology (g-LIMIT) has been built by the NASA Marshall Space Flight Center to attenuate the nominal acceleration environment and provide some isolation for microgravity science experiments. The g-LIMIT uses Lorentz (voice-coil) magnetic actuators to isolate a platform, for mounting science payloads, from the nominal acceleration environment. The system utilizes payload-acceleration, relative-position, and relative-orientation measurements in a feedback controller to accomplish the vibration isolation task. The controller provides current commands to six magnetic actuators, producing the required experiment isolation from the ISS acceleration environment. The present work documents the development of a candidate control law to meet the acceleration attenuation requirements for the g-LIMIT experiment platform. The controller design is developed using linear optimal control techniques for frequency-weighted H2 norms. Comparison of performance and robustness to plant uncertainty for this control design approach is included in the discussion. System performance is demonstrated in the presence of plant modeling error.

Calhoun, Philip C.↗
NASA NTRS1988

Physiological adaptation - Crew health in space

The experiments planned for the Spacelab Life Sciences-1 (SLS-1) Shuttle mission, which is dedicated to investigating biomedical issues pertinent to the man's presence in space, are discussed. The areas of research will include human and animal experiments concerned with the cardiovascular system, the vestibular apparatus, and metabolic experiments related to renal endocrine function, hematology, immune system, and muscle and bone/calcium metabolism, with particular attention given to the physiological complications resulting from short-duration space flight and subsequent return to the 1-G environment. The hardware systems to be used on the SLS-1 mission represent prototypes of systems to be developed for the medical and research facilities of the Space Station. The results of the experiments will be used to address issues related to long-duration space flight required for the Space Station and interplanetary travels.

Brand, Susan↗
NASA NTRS1989

Laboratory simulations of energetic atom interactions occurring in low earth orbit

The Space Shuttle flights provided the first significant data base on the environment experienced by a large space structure operating in LEO. A number of interesting and unanticipated effects were observed, including material erosion induced by ambient oxygen atoms, the visible Shuttle glow occurring above surfaces exposed to the ram flow, and large near-field perturbations and variability in the gaseous neutral and plasma environment about the Shuttle. This paper provides a brief overview of these observations and their phenomenological interpretation, and then discusses laboratory approaches to their investigation. The emphasis is on the state of the art in the development of energetic oxygen atoms sources and the variety of experiments presently being performed with such devices.

Caledonia, G. E.↗
NASA NTRS1987

Characterization of neurospora circadian rhythms in space

To determine whether the circadian rhythm of conidiation in neurospora crassa is endogenously derived or is driven by some geophysical time cue, an experiment was conducted on space shuttle flight STS-9, where inoculated race tubes were exposed to the microgravity environment of space. The results demonstated that the rhythm can persist in space. However, there were several minor alterations noted; an increase in the period of the oscillation and the variability of the growth rate and a diminished rhythm amplitude, which eventually damped out in 25% of the flight tubes. On day seven of the flight, the tubes were exposed to light while their growth fronts were marked. It appears that some aspects of this marking process reinstated a robust rhythm in all the tubes which continued throughout the remainder of the flight. It was hypothesized that the damping found prior to the marking procedure on STS-9 may have been a result of the hypergravity pulse of launch and not due to the microgravity of the orbital lab; furthermore, that the marking procedure, by exposing the samples to light, had reinstated rhythmicity. To test this, an investigation was conducted into the effects of acute and chronic exposure to hypergravity.

Ferraro, James S.↗