Search NASA⌕ Search

SEARCH · Search NASA

Results for “Solar Probe”

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 577 records · Page 32

Solar Power for Near Sun, High-Temperature Missions

Existing solar cells lose performance at the high temperatures encountered in Mercury orbit and inward toward the sun. For future missions designed to probe environments close to the sun, it is desirable to develop array technologies for high temperature and high light intensity. Approaches to solar array design for near-sun missions include modifying the terms governing temperature of the cell and the efficiency at elevated temperature, or use of techniques to reduce the incident solar energy to limit operating temperature. An additional problem is found in missions that involve a range of intensities, such as the Solar Probe + mission, which ranges from a starting distance of 1 AU from the sun to a minimum distance of 9.5 solar radii, or 0.044 AU. During the mission, the solar intensity ranges from one to about 500 times AM0. This requires a power system to operate over nearly three orders of magnitude of incident intensity.

Landis, Geoffrey A.↗

A compact spectroradiometer for solar simulator measurements

Compact spectral irradiance probe has been designed and built which uses wedge filter in conjunction with silicon cell and operational amplifier. Probe is used to monitor spectral energy distribution of solar simulators and other high intensity sources.

Seward, H. H.↗

How active was solar cycle 22?

Solar EUV observations from the Langmuir probe on Pioneer Venus Orbiter suggest that at EUV wavelengths solar cycle 22 was more active than solar cycle 21. The Langmuir probe, acting as a photodiode, measured the integrated solar EUV flux over a 13 1/2 year period from January 1979 to June 1992, the longest continuous solar EUV measurement. The Ipe EUV flux correlated very well with the SME measurement of L-alpha during the lifetime of SME and with the UARS SOLSTICE L-alpha from October 1991 to June 1992 when the Ipe measurement ceased. Starting with the peak of solar cycle 21, there was good general agreement of Ipe EUV with the 10.7 cm, Ca K, and He 10830 solar indices, until the onset of solar cycle 22. From 1989 to the start of 1992, the 10.7 cm flux exhibited a broad maximum consisting of two peaks of nearly equal magnitude, whereas Ipe EUV exhibited a strong increase during this time period making the second peak significantly higher than the first. The only solar index that exhibits the same increase in solar activity as Ipe EUV and L-alpha during the cycle 22 peak is the total magnetic flux. The case for high activity during this peak is also supported by the presence of very high solar flare intensity.

Hoegy, W. R.↗

Experimental measurements of the plasma sheath around pinhole defects in a simulated high-voltage solar array

An emissive Langmuir probe was used to measure the potentials within the plasma sheath developed around a hole in a simulated solar array at voltages between 50 and 450 V. The hole sizes were larger than actual pinhole defects; the plasma density was in the 10,000 per cu cm range, which is considerably lower than the density of 1,000,000 per cu cm found at low-earth-orbit altitudes. Despite these inadequacies in the simulation, the experiments indicate that this type of probe is a useful diagnostic technique for investigating the plasma sheaths developing around pinhole defects.

Gabriel, S. B.↗

500 C Electronic Packaging and Dielectric Materials for High Temperature Applications

High-temperature environment operable sensors and electronics are required for exploring the inner solar planets and distributed control of next generation aeronautical engines. Various silicon carbide (SiC) high temperature sensors, actuators, and electronics have been demonstrated at and above 500C. A compatible packaging system is essential for long-term testing and application of high temperature electronics and sensors. High temperature passive components are also necessary for high temperature electronic systems. This talk will discuss ceramic packaging systems developed for high temperature electronics, and related testing results of SiC circuits at 500C and silicon-on-insulator (SOI) integrated circuits at temperatures beyond commercial limit facilitated by these high temperature packaging technologies. Dielectric materials for high temperature multilayers capacitors will also be discussed. High-temperature environment operable sensors and electronics are required for probing the inner solar planets and distributed control of next generation aeronautical engines. Various silicon carbide (SiC) high temperature sensors, actuators, and electronics have been demonstrated at and above 500C. A compatible packaging system is essential for long-term testing and eventual applications of high temperature electronics and sensors. High temperature passive components are also necessary for high temperature electronic systems. This talk will discuss ceramic packaging systems developed for high electronics and related testing results of SiC circuits at 500C and silicon-on-insulator (SOI) integrated circuits at temperatures beyond commercial limit facilitated by high temperature packaging technologies. Dielectric materials for high temperature multilayers capacitors will also be discussed.

dielectric performance↗

Turbulence and scintillations in the interplanetary plasma.

The properties of the broadband fluctuations of the interplanetary plasma are discussed, taking into account observations in the vicinity of 1 AU heliocentric radius on space probes. Aspects of interplanetary scintillations and angular broadening as a probe of the solar wind are considered, giving attention to the 'thin-screen' approximation, a three-dimensional model of interplanetary scintillations, the structure of density fluctuations, and the determination of solar wind velocity from scintillations. It is pointed out that the theoretical understanding of the origin and evolution of the fluctuations and their full import for the solar wind is still at a relatively rudimentary stage.

Jokipii, J. R.↗

Nature of the ultraviolet absorber in the Venus clouds - Inferences based on Pioneer Venus data

Several photometric measurements of Venus made from the Pioneer Venus orbiter and probes indicate that solar near-ultraviolet radiation is being absorbed throughout much of the main cloud region, but little above the clouds or within the first one or two optical depths. Radiative transfer calculations were carried out to simulate both Pioneer Venus and ground-based data for a number of proposed cloud compositions. This comparison rules out models invoking nitrogen dioxide, meteoritic material, and volatile metals as the source of the ultraviolet absorption. Models involving either small (approximately 1 micrometer) or large (approximately 10 micrometers) sulfur particles have same serious difficulties, while ones invoking sulfur dioxide gas appear to be promising.

Pollack, J. B.↗

Cost reduction in space operations - Structuring a planetary program to minimize the annual funding requirement as opposed to minimizing the program runout cost

An approach is proposed for the structuring of a planetary mission set wherein the peak annual funding is minimized to meet the annual budget restraint. One aspect of the approach is to have a transportation capability that can launch a mission in any planetary opportunity; such capability can be provided by solar electric propulsion. Another cost reduction technique is to structure a mission test in a time sequenced fashion that could utilize essentially the same spacecraft for the implementation of several missions. A third technique would be to fulfill a scientific objective in several sequential missions rather than attempt to accomplish all of the objectives with one mission. The application of the approach is illustrated by an example involving the Solar Orbiter Dual Probe mission.

Herman, D. H.↗

Recent Ground-based Observations of the Global Properties of the Sun

Ground based observations have achieved sufficient sensitivity and duration to scrutinize many global properties of the Sun. Variations in the properties of granular and supergranular convection are measured. The surface rotation measurements continue to present contradictory results. A spectrum of torsional motions are detected. A variety of oscillation measurements now are available for nearly direct probing of the solar interior.

Labonte, B. J.↗

Shutters and slats for the integral sunshade of an optical reception antenna

Optical reception antennas used at a small Sun-Earth-probe angle (small solar elongation E) require sunshading to prevent intolerable scattering of light from the surface of the primary mirror. An integral sunshade consisting of hexagonal tubes aligned with the segmentation of a large mirror was proposed for use down to E = 12 degrees. For smaller angles, asterisk-shaped vanes inserted into the length of the hexagonal tubes would allow operation down to about 6 degrees with a fixed obscuration of 3.6 percent. Two alternative methods are investigated to extend the usefulness of the integral sunshade to smaller angles by adding either variable-area shutters to block the tube corners that admit off-axis sunlight or by inserting slats (partial vanes) down the full length of some tubes. Slats are effective for most operations down to 6 degrees, and obscure only 1.2 percent. For E between 10.75 and 12 degrees, shutters cause even less obscuration.

Kerr, E. L.↗

Packaging Technology Designed, Fabricated, and Assembled for High-Temperature SiC Microsystems

A series of ceramic substrates and thick-film metalization-based prototype microsystem packages designed for silicon carbide (SiC) high-temperature microsystems have been developed for operation in 500 C harsh environments. These prototype packages were designed, fabricated, and assembled at the NASA Glenn Research Center. Both the electrical interconnection system and the die-attach scheme for this packaging system have been tested extensively at high temperatures. Printed circuit boards used to interconnect these chip-level packages and passive components also are being fabricated and tested. NASA space and aeronautical missions need harsh-environment, especially high-temperature, operable microsystems for probing the inner solar planets and for in situ monitoring and control of next-generation aeronautical engines. Various SiC high-temperature-operable microelectromechanical system (MEMS) sensors, actuators, and electronics have been demonstrated at temperatures as high as 600 C, but most of these devices were demonstrated only in the laboratory environment partially because systematic packaging technology for supporting these devices at temperatures of 500 C and beyond was not available. Thus, the development of a systematic high-temperature packaging technology is essential for both in situ testing and the commercialization of high-temperature SiC MEMS. Researchers at Glenn developed new prototype packages for high-temperature microsystems using ceramic substrates (aluminum nitride and 96- and 90-wt% aluminum oxides) and gold (Au) thick-film metalization. Packaging components, which include a thick-film metalization-based wirebond interconnection system and a low-electrical-resistance SiC die-attachment scheme, have been tested at temperatures up to 500 C. The interconnection system composed of Au thick-film printed wire and 1-mil Au wire bond was tested in 500 C oxidizing air with and without 50-mA direct current for over 5000 hr. The Au thick-film metalization-based wirebond electrical interconnection system was also tested in an extremely dynamic thermal environment to assess thermal reliability. The I-V curve1 of a SiC high-temperature diode was measured in oxidizing air at 500 C for 1000 hr to electrically test the Au thick-film material-based die-attach assembly.

Chen, Liang-Yu↗

Cascade Helps JPL Explore the Solar System

At Jet Propulsion Laboratory (JPL), we are involved with the unmanned exploration of the solar system. Unmanned probes observe the planet surfaces using radar and optical cameras to take a variety of measurements.

maximum likelihood decoder mcd asic viterbi encodi↗

Hyperbolic Orbits and the Planetary Flylby Anomaly

Space probes in the Solar System have experienced unexpected changes in velocity known as the flyby anomaly [1], as well as shifts in acceleration referred to as the Pioneer anomaly [2-4]. In the case of Earth flybys, ESA s Rosetta spacecraft experienced the flyby effect and NASA s Galileo and NEAR satellites did the same, although MESSENGER did not possibly due to a latitudinal property of gravity assists. Measurements indicate that both anomalies exist, and explanations have varied from the unconventional to suggestions that new physics in the form of dark matter might be the cause of both [5]. Although dark matter has been studied for over 30 years, there is as yet no strong experimental evidence supporting it [6]. The existence of dark matter will certainly have a significant impact upon ideas regarding the origin of the Solar System. Hence, the subject is very relevant to planetary science. We will point out here that one of the fundamental problems in science, including planetary physics, is consistency. Using the well-known virial theorem in astrophysics, it will be shown that present-day concepts of orbital mechanics and cosmology are not consistent for reasons having to do with the flyby anomaly. Therefore, the basic solution regarding the anomalies should begin with addressing the inconsistencies first before introducing new physics.

Wilson, T.L.↗

Alumina Based 500 C Electronic Packaging Systems and Future Development

NASA space and aeronautical missions for probing the inner solar planets as well as for in situ monitoring and control of next-generation aeronautical engines require high-temperature environment operable sensors and electronics. A 96% aluminum oxide and Au thick-film metallization based packaging system including chip-level packages, printed circuit board, and edge-connector is in development for high temperature SiC electronics. An electronic packaging system based on this material system was successfully tested and demonstrated with SiC electronics at 500 C for over 10,000 hours in laboratory conditions previously. In addition to the tests in laboratory environments, this packaging system has more recently been tested with a SiC junction field effect transistor (JFET) on low earth orbit through the NASA Materials on the International Space Station Experiment 7 (MISSE7). A SiC JFET with a packaging system composed of a 96% alumina chip-level package and an alumina printed circuit board mounted on a data acquisition circuit board was launched as a part of the MISSE7 suite to International Space Station via a Shuttle mission and tested on the orbit for eighteen months. A summary of results of tests in both laboratory and space environments will be presented. The future development of alumina based high temperature packaging using co-fired material systems for improved performance at high temperature and more feasible mass production will also be discussed.

Chen, Liang-Yu↗

Space Launch System Payload Stage Capability for Ultra-High Characteristic Energy Missions

The Space Launch System (SLS) vehicle is NASA’s cornerstone capability for a new era of human and robotic exploration of deep space. The unrivalled performance of SLS provides the capability to launch the first woman and next man to walk on the lunar surface and to support development of a sustained human presence in cislunar space, and ultimately human missions to Mars. As an evolvable capability with unique launch performance, the opportunities enabled by SLS also include game-changing benefits for science missions, including probes to the outer solar system and beyond. For the last two years, the SLS Program has worked with the Interstellar Probe team at the Johns Hopkins University Applied Physics Laboratory(APL) to provide data that describe how SLS could support a mission that would break through the boundary of the heliosphere and into pristine interstellar space only a decade after launch, enabling earlier science return and greatly increasing spacecraft life in the interstellar medium. In record-breaking time, the ISP as launched on SLS may answer questions raised by the extended mission of NASA’s Voyager spacecraft. While SLS and its efficient Exploration Upper Stage (EUS) offer benefits for exploration of the outer planets, adding one or more additional stages to this architecture makes it even more capable for missions beyond our solar system, offering more realistically appealing flight times that would allow the mission scientists to reap the rewards of exploration. During the time the SLS Program has been working with the Interstellar Probe team, it has identified an expedited path to the Block 2 capability planned for the Interstellar Probe mission, and further matured performance numbers for diverse multi-stage configurations using a combination of commercially available liquid hydrogen (LH2)/liquid oxygen (LOX) upper stages and solid motor kick stages. That work has demonstrated the SLS payload stage capability provides significant benefits and opens trade space for multiple missions in consideration during planning for the next Planetary Science and Astrobiology Decadal Survey. This presentation details the significant benefits SLS can provides for very high characteristic (C3) energy missions by coupling the capabilities of SLS to current commercial rocket propulsion stage systems. These capabilities are explored specifically in the context of an Interstellar Probe architecture in which a small, capable science probe, coupled with carefully tailored mission design trajectories, could be used to explore the outer solar system and the interstellar medium. The presentation will also address the operational logistics of integrating such a mission, explaining the options available for “non-standard” SLS payloads, including processing those with radioisotope power generators or additional propulsion stages. An SLS system overview and capabilities will be presented, along with vehicle configuration and orbit performance capability studies, explaining how SLS is enabling for a variety of high-energy science mission profiles, including launching an exploratory probe bound for interstellar space only a decade after launch.

Rob Stough↗