Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Solar Futures Study”

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 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
NASA NTRS2018

Toolbox for Research and Exploration (TREX): Investigations of Fine-Grained Materials on Small Bodies

The Toolbox for Research and Exploration (TREX) is a NASA SSERVI (Solar System Exploration Research Virtual Institute) node. TREX (trex.psi.edu) aims to decrease risk to future missions, specifically to the Moon, the Martian moons, and near- Earth asteroids, by improving mission success and assuring the safety of astronauts, their instruments, and spacecraft. TREX studies will focus on characteristics of the fine grains that cover the surfaces of these target bodies - their spectral characteristics and the potential resources (such as H2O) they may harbor. TREX studies are organized into four Themes (Laboratory- Studies, Moon-Studies, Small-Bodies Studies, and Field-Work). In this presentation, we focus on the work targeted by the Small-Bodies Theme. The Small-Bodies' Theme delves into several topics, many which overlap or are synergistic with the other TREX Themes. The main topics include photometry, spectral modeling, laboratory simulations of space weathering processes relevant to asteroids, the assembly of an asteroid regolith database, the dichotomy between nuclear and reflectance spectroscopy, and the dynamical evolution of asteroids and the implications for the retention of volatiles.

Domingue, D. L.↗
NASA NTRS1990

Heating and melting of small icy satellites by the decay of 26Al

We study the effect of radiogenic heating due to 26Al on the thermal evolution of small icy satellites. Our object is to find the extent of internal melting as a function of the satellite radius and of the initial 26Al abundance. The implicit assumption, based on observations of young stars, is that planet and satellite accretion occurred on a time scale of approximately 10(6) yr (comparable with the lifetime of 26Al). The icy satellites are modeled as spheres of initially amorphous ice, with chondritic abundances of 40K, 232Th, 235U, 238U, corresponding to an ice/dust mass ratio of 1. Evolutionary calculations are carried out, spanning 4.5 x 10(9) yr, for different combinations of the two free parameters. Heat transfer by subsolidus convection is neglected for these small satellites. Our main conclusion is that the initial 26Al abundance capable of melting icy bodies of satellite size to a significant extent is more than 10 times lower than that prevailing in the interstellar medium (or that inferred from the Ca-Al rich inclusions of the Allende meteorite, approximately 7 x 10(-7) by mass). We find, for example, that an initial 26Al mass fraction of approximately 4 x 10(-8) is sufficient for melting almost completely icy spheres with radii of 800 km, typical of the larger icy planetary satellites. We also find that for any given 26Al abundance, there is a narrow range of radii below which only marginal melting occurs and above which most of the ice melts (and refreezes later). Since extensive melting may have important consequences, such as differentiation, gas release, and volcanic activity, the effect of 26Al should be included in future studies of satellite interiors.

Non-NASA Center↗
NASA NTRS2001

Sensitivity Studies for Space-Based Global Measurements of Atmospheric Carbon Dioxide

Carbon dioxide (CO2) is well known as the primary forcing agent of global warming. Although the climate forcing due to CO2 is well known, the sources and sinks of CO2 are not well understood. Currently the lack of global atmospheric CO2 observations limits our ability to diagnose the global carbon budget (e.g., finding the so-called "missing sink") and thus limits our ability to understand past climate change and predict future climate response. Space-based techniques are being developed to make high-resolution and high-precision global column CO2 measurements. One of the proposed techniques utilizes the passive remote sensing of Earth's reflected solar radiation at the weaker vibration-rotation band of CO2 in the near infrared (approx. 1.57 micron). We use a line-by-line radiative transfer model to explore the potential of this method. Results of sensitivity studies for CO2 concentration variation and geophysical conditions (i.e., atmospheric temperature, surface reflectivity, solar zenith angle, aerosol, and cirrus cloud) will be presented. We will also present sensitivity results for an O2 A-band (approx. 0.76 micron) sensor that will be needed along with CO2 to make surface pressure and cloud height measurements.

Mao, Jian-Ping↗
NASA NTRS1971

Radio propagation measurements of the solar corona and gravitational fields: Applications to Mariner 6 and 7

Results from interferometric measurements of the apparent angular deflection of quasi-stellar object are examined. Some preliminary results from Mariner 6 and 7 experiments, particularly from the plasma effect viewpoint, are discussed, along with future experiments and plasma scintillation. Ray bending studies, plasma relativity separation for Mariner 6 and 7, and radio propagation test of general relativity are reviewed. First order approximations and time delay studies are appended, as well as Doppler velocity effect investigations.

Muhleman, D. O.↗
NASA NTRS1983

Solar diameter measurements for study of Sun climate coupling

Changes in solar shape and diameter were detected as a possible probe of variability in solar luminosity, an important climatic driving function. A technique was designed which will allow the calibration of the telescope field, providing a scale for long-term comparison of these and future measurements.

Hill, H. A.↗
NASA NTRS1975

New horizons

The contribution of space exploration and space related research to the future of man and the accomplishments of the space program are assessed. Topics discussed include: the role of applications satellites in crop surveillance, land use surveys, weather forecasting, education, communications, and pollution monitoring; planetary studies which examine the origin and evolution of the solar system, including dynamic processes that bear directly on earth's environment; and fuel conservation and development of new energy sources.

Source record↗
NASA NTRS2000

Status of The SPARC-GRIPS Initiative

The GCM-Reality Intercomparison Project for the Symbolic Processing Algorithmic Research Computer (SPARC) is an initiative designed to provide a comprehensive assessment of our ability to model the present-day climate and the impacts of different physical perturbations. This poster will show the different scientific experiments being conducted in the general purpose rocket instrumentation and payload system (GRIPS) and include some summaries of the results. The three concurrent aspects of GRIPS are: (1) studies of the climate and transient features simulated by the models; (2) examinations of different parametrizations and their impacts on the model climate; (3) studies of the impact of physical perturbations, such as solar forcing, volcanic aerosols and ozone change. Sample results from a number of these areas will be presented, with discussion of their implications for our ability to model the climate of the present and future atmosphere.

Pawson, Steven↗
NASA NTRS2016

Plasma Oscillation Characterization of NASA's HERMeS Hall Thruster via High Speed Imaging

For missions beyond low Earth orbit, spacecraft size and mass can be dominated by onboard chemical propulsion systems and propellants that may constitute more than 50 percent of the spacecraft mass. This impact can be substantially reduced through the utilization of Solar Electric Propulsion (SEP) due to its substantially higher specific impulse. Studies performed for NASA's Human Exploration and Operations Mission Directorate and Science Mission Directorate have demonstrated that a 50kW-class SEP capability can be enabling for both near term and future architectures and science missions. A high-power SEP element is integral to the Evolvable Mars Campaign, which presents an approach to establish an affordable evolutionary human exploration architecture. To enable SEP missions at the power levels required for these applications, an in-space demonstration of an operational 50kW-class SEP spacecraft has been proposed as a SEP Technology Demonstration Mission (TDM). In 2010 NASA's Space Technology Mission Directorate (STMD) began developing high-power electric propulsion technologies. The maturation of these critical technologies has made mission concepts utilizing high-power SEP viable.

Ground Tests↗
NASA NTRS1977

Photometry of satellite surfaces

A review is presented of basic photometric concepts as they apply to the study of the surfaces of natural satellites. The analysis of brightness variations related to changes in solar phase angle, the longitude of the satellite in its orbit about the primary, and other factors is discussed, together with the derivation of phase integrals. The method used to determine geometric albedos is outlined, and major uncertainties in determined values are considered. Photometric results obtained for satellites of Mars and Jupiter are summarized. Leading side/trailing side brightness trends characteristic of the inner satellites of these planets and lightcurve color amplitude trends are examined. Priority areas for future photometric studies are identified.

Veverka, J.↗
NASA NTRS1997

Bidirectional Reflectance Functions for Application to Earth Radiation Budget Studies

Reflected solar radiative fluxes emerging for the Earth's top of the atmosphere are inferred from satellite broadband radiance measurements by applying bidirectional reflectance functions (BDRFs) to account for the anisotropy of the radiation field. BDRF's are dependent upon the viewing geometry (i.e. solar zenith angle, view zenith angle, and relative azimuth angle), the amount and type of cloud cover, the condition of the intervening atmosphere, and the reflectance characteristics of the underlying surface. A set of operational Earth Radiation Budget Experiment (ERBE) BDRFs is available which was developed from the Nimbus 7 ERB (Earth Radiation Budget) scanner data for a three-angle grid system, An improved set of bidirectional reflectance is required for mission planning and data analysis of future earth radiation budget instruments, such as the Clouds and Earth's Radiant Energy System (CERES), and for the enhancement of existing radiation budget data products. This study presents an analytic expression for BDRFs formulated by applying a fit to the ERBE operational model tabulations. A set of model coefficients applicable to any viewing condition is computed for an overcast and a clear sky scene over four geographical surface types: ocean, land, snow, and desert, and partly cloudy scenes over ocean and land. The models are smooth in terms of the directional angles and adhere to the principle of reciprocity, i.e., they are invariant with respect to the interchange of the incoming and outgoing directional angles. The analytic BDRFs and the radiance standard deviations are compared with the operational ERBE models and validated with ERBE data. The clear ocean model is validated with Dlhopolsky's clear ocean model. Dlhopolsky developed a BDRF of higher angular resolution for clear sky ocean from ERBE radiances. Additionally, the effectiveness of the models accounting for anisotropy for various viewing directions is tested with the ERBE along tract data. An area viewed from nadir and from the side give two different radiance measurements but should yield the same flux when converted by the BDRF. The analytic BDRFs are in very good qualitative agreement with the ERBE models. The overcast scenes exhibit constant retrieved albedo over viewing zenith angles for solar zenith angles less than 60 degrees. The clear ocean model does not produce constant retrieved albedo over viewing zenith angles but gives an improvement over the ERBE operational clear sky ocean BDRF.

Manalo-Smith, N.↗
NASA NTRS1974

Skylab report - Man's role in space research

Some of the early results reported by several investigators in the solar physics discipline are described, as well as a subjective response to long-term zero-gravity exposure in several areas related to medical studies. Many of the roles in which man has participated in research aboard Skylab will again be important in future space activities such as the Space Shuttle. Examples are pointing, alignment, transient identification and response, and assurance of data quality. These tasks can be extended to include a greater role in data management and interpretation, so that some selectivity or processing, or both, might be appropriate onboard the spacecraft, prior to transmission of data to the ground.

Garriott, O. K.↗
NASA NTRS1999

Performance Simulation of Autonomous Solar Navigation

The performance of a new type of autonomous solar navigation system is analyzed in this paper. Such efficient autonomous navigation systems will reduce operation costs and alleviate the Deep Space Network workload in future space missions. The method is demonstrated by applying it to the STEREO mission. Orbit determination is simulated through the use of the mission-defined trajectory profile and solar angular data acquired by the on-board science instruments currently being considered. The study shows that the orbit solution derived by this new type of solar navigation system can satisfy the mission's navigation requirements; the position uncertainties obtained in the simulations are well below the mission allowable values, and are comparable to the results obtained with the conventional Doppler tracking system in some cases.

Guo, Yanping↗
NASA NTRS2009

MODIS Solar Reflective Calibration Traceability

Long-term climate data records often consist of observations made by multiple sensors. It is, therefore, extremely important to have instrument overlap, to be able to track instrument stability, to quantify, measurement uncertainties, and to establish absolute scale traceable to the International System of Units (SI). The Moderate Resolution Imaging Spectroradiometer (MODIS) is a key instrument for both the Terra and Aqua missions, which were launched in December 1999 and May 2002, respectively. It has 20 reflective solar bands (RSB) with wavelengths from 0.41 to 2.2 micrometers and observes the Earth at three nadir spatial resolutions: 0.25km, 0.5km, and 1km. MODIS RSB on-orbit calibration is reflectance based with reference to the bidirectional reflectance factor (BRF) of its on-board solar diffuser (SD). The SD BRF characterization was made pre-launch by the instrument vendor using reference samples traceable directly to the National Institute of Standards and Technology (NIST). On-orbit SD reflectance degradation is tracked by an on-board solar diffuser monitor (SDSM). This paper provides details of this calibration chain, from prelaunch to on-orbit operation, and associated uncertainty assessments. Using MODIS as an example, this paper also discusses challenges and key design requirements for future missions developed for accurate climate studies.

Xiong, Xiaoxiong↗
NASA NTRSDate not supplied

Research Activities at NASA: “The Hera Astronaut Analog Mission, Astrobee, and the Advanced Composite Solar Sail System”

During this seminar, I will talk about three of the projects I’ve been involved with at NASA in the last few years: - The Human Exploration Research Analog (HERA) is a ground-based astronaut analog mission run at NASA’s JSC in Houston to study and evaluate impacts on the crew due to isolation, remoteness, and confined habitation. NASA scientists use the collected data to develop and verify countermeasures to reduce or mitigate psychological and physiological effects for future Deep Space missions. This simulation was a 45-day trip to Mars’s moon Phobos and back with the goal of performing geological operations with complete communications delays in effect. - Astrobee is a new class of free-flying robots that operates in the interior of the International Space Station (ISS). In addition to being a research platform for microgravity free-flying robotics, Astrobee improves the efficiency of ISS operations by providing flight and payload controllers with a mobile camera and a sensor platform. - NASA is developing new deployable structures and material technologies for solar sail propulsion systems destined for future low-cost deep space missions. NASA’s Advanced Composite Solar Sail System (ACS3) uses composite materials in its novel, lightweight booms that deploy from a Cubesat. Data obtained from ACS3 will guide the design of future larger-scale composite solar sail systems that could be used for several deep space exploration missions

International Space Station↗
NASA NTRS2006

Can We Power Future Mars Missions?

The Vision for Space Exploration identified the exploration of Mars as one of the key pathways. In response, NASAs Mars Program Office is developing a detailed mission lineup for the next decade that would lead to future explorations. Mission architectures for the next decade include both orbiters and landers. Existing power technologies, which could include solar panels, batteries, radioisotope power systems, and in the future fission power, could support these missions. Second and third decade explorations could target human precursor and human in-situ missions, building on increasingly complex architectures. Some of these could use potential feed forward from earlier Constellation missions to the Moon, discussed in the ESAS study. From a potential Mars Sample Return mission to human missions the complexity of the architectures increases, and with it the delivered mass and power requirements also amplify. The delivered mass at Mars mostly depends on the launch vehicle, while the landed mass might be further limited by EDL technologies, including the aeroshell, parachutes, landing platform, and pinpoint landing. The resulting in-situ mass could be further divided into payload elements and suitable supporting power systems. These power systems can range from tens of watts to multi-kilowatts, influenced by mission type, mission configuration, landing location, mission duration, and season. Regardless, the power system design should match the power needs of these surface assets within a given architecture. Consequently, in this paper we will identify potential needs and bounds of delivered mass and architecture dependent power requirements to surface assets that would enable future in-situ exploration of Mars.

solar panels↗
NASA NTRS1975

Man's future in space

Studies evaluating potential operational and commercial uses of space are being conducted, taking into account astronomy, astrophysics, manned bases and laboratories in earth orbit, space colonization, terrestrial communications, space processing and manufacturing, interstellar probes, planetary exploration, and the use of space for terrestrial energy supply. The present status in the exploration of the solar system is examined, giving attention to Jupiter, Venus, Mars, and Mercury. A brief outline of the development of human colonies on Mars is presented.

Freitag, R. F.↗
NASA NTRS1994

Max 1991 and beyond

Max '91, a coordinated, broad based observational program, was designed to help maximize the scientific return of solar activity studies. Max '91 benefited from the support of the NOAA space environment laboratory. An important source that increases solar ground based support observations is the solar observing optical network (SOON) solar patrol on tape (SOONSPOT) solar image archival system which has started operations. The past means and the future plans for ground based coordination and communications of Max '91 are summarized. The current status and the future developments of SOONSPOT are presented.

Kiplinger, Alan L.↗
NASA NTRS2008

Retrievals of Thick Cloud Optical Depth from the Geoscience Laser Altimeter System (GLAS) by Calibration of Solar Background Signal

Laser beams emitted from the Geoscience Laser Altimeter System (GLAS), as well as other space-borne laser instruments, can only penetrate clouds to a limit of a few optical depths. As a result, only optical depths of thinner clouds (< about 3 for GLAS) are retrieved from the reflected lidar signal. This paper presents a comprehensive study of possible retrievals of optical depth of thick clouds using solar background light and treating GLAS as a solar radiometer. To do so we first calibrate the reflected solar radiation received by the photon-counting detectors of GLAS' 532 nm channel, which is the primary channel for atmospheric products. The solar background radiation is regarded as a noise to be subtracted in the retrieval process of the lidar products. However, once calibrated, it becomes a signal that can be used in studying the properties of optically thick clouds. In this paper, three calibration methods are presented: (I) calibration with coincident airborne and GLAS observations; (2) calibration with coincident Geostationary Operational Environmental Satellite (GOES) and GLAS observations of deep convective clouds; (3) calibration from the first principles using optical depth of thin water clouds over ocean retrieved by GLAS active remote sensing. Results from the three methods agree well with each other. Cloud optical depth (COD) is retrieved from the calibrated solar background signal using a one-channel retrieval. Comparison with COD retrieved from GOES during GLAS overpasses shows that the average difference between the two retrievals is 24%. As an example, the COD values retrieved from GLAS solar background are illustrated for a marine stratocumulus cloud field that is too thick to be penetrated by the GLAS laser. Based on this study, optical depths for thick clouds will be provided as a supplementary product to the existing operational GLAS cloud products in future GLAS data releases.

Yang, Yuekui↗