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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 217 records · Page 12
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NASA NTRS1982

Data and data retrieval in space astronomy

To illustrate the range of storage and retrieval facilities and data products that are involved in space astronomy, the present situation on data from some instruments on the following missions is presented: Small Astronomy Satellite-B, Orbiting Astronomical Observatory 3, High Energy Astrophysics Observatory 2, International Ultraviolet Explorer, Viking Orbiter, and Solar Maximum Mission. In addition, the Coordinated Data Analysis Workshops conducted at the National Space Science Data Center are outlined to demonstrate the usefulness of building a problem-oriented on-line data base from instruments flown on a number of spacecraft and operating from ground-based facilities.

Vette, J. I.↗
NASA NTRS1984

Flare build-up study - Homologous flares group. I

Solar Maximum Mission observations have been used to study the origin and amount of energy, mechanism of storage and release, and conditions for the occurrence of solar flares, and some results of these studies as they pertain to homologous flares are briefly discussed. It was found that every set of flares produced 'rafales' of homologous flares, i.e., two, three, four, or more flares separated in time by an hour or less. No great changes in macroscopic photospheric patterns were observed during these flaring periods. A quantitative brightness parameter of the relation between homologous flares is defined. Scale changes detected in the dynamic spectrum of flare sites are in good agreement with a theoretical suggestion by Sturrock. Statistical results for different homologous flare active regions show the existence in homologous flaring areas of a 'pivot' of previous filaments interpreted as a signature of an anomaly in the solar rotation.

Martres, M.-J.↗
NASA NTRS1986

Dust collection on serviceable satellites

One rationale for the Space Shuttle program which was dramatically realized during the repair of the Solar Maximum Mission (SMM) is the efficiency of in-orbit satellite servicing. An unexpected benefit of this repair mission was the return of parts of the Solar Max satellite which had been exposed for four years to the space environment. Studies conducted on these parts have yielded valuable data on the micrometeorite flux and composition at shuttle altitudes during this time period. The scientific results from studies of the cosmic dust component of the observed particle impacts are not yet complete but it is clear from the preliminary data available that such studies will be a valuable adjunct to the studies of cosmic dust particles collected in the atmosphere. The success of the initial studies of particles collected during repairs of the SMM spacecraft on a surface not specifically designed as a particle collector nor retrieved in a manner intended to minimize or eliminate local contamination raises the possibility that even more interesting results might be obtained if serviceable satellites were initially designed with these objectives in mind. All designs for modern satellites utilize some form of thermal blanket material in order to minimize thermal stresses inside the spacecraft. It is proposed that all future satellites be designed with standardized removeable sections of thermal blanket material which could be replaced during on-orbit servicing and returned to earth for detailed study.

Nuth, J. A., III↗
NASA NTRS1982

Fluorescent excitation of photospheric Fe K-alpha emission during solar flares

The Bent Crystal Spectrometer on the NASA Solar Maximum Mission satellite provides high spectral and temporal resolution observations of the Fe K-alpha lines. Analyses have been conducted of spectra from almost 50 solar flares that occurred during 1980. These data strongly support fluorescent excitation of photospheric iron by photons of E greater than 7.11 keV emitted by the hot coronal plasma produced during the flare. After comparison of the data with a model, the observed K-alpha line widths are discussed along with estimates of the size of the emitting region, the height of the coronal source and the photospheric iron abundance.

Parmar, A. N.↗
NASA NTRS1988

Explosive plasma flows in a solar flare

Solar Maximum Mission soft X-ray data and Sacramento Peak Observatory H-alpha observations are combined in a study of the impulsive phase of a solar flare. A blue asymmetry, indicative of upflows, was observed in the coronal Ca XIX line during the soft X-ray rise phase. A red asymmetry, indicative of downflows, was observed simultaneously in chromospheric H-alpha emitted from bright flare kernels during the period of hard X-ray emission. Combining the velocity data with a measurement of coronal electron density, it is shown that the impulsive phase momentum of upflowing soft X-ray-emitting plasma equalled that of the downflowing H-alpha-emitting plasma to within one order of magnitude. In particular, the momentum of the upflowing plasma was 2 x 10 to the 21st g cm/s while that of the downflowing plasma was 7 x 10 to the 21st g cm/s, with a factor of 2 uncertainty on each value. This equality supports the explosive chromospheric evaporation model of solar flares, in which a sudden pressure increase at the footprint of a coronal loop produces oppositely directed flows in the heated plasma.

Zarro, Dominic M.↗
NASA NTRS1989

Determination of solar flare accelerated ion angular distributions from SMM gamma ray and neutron measurements and determination of the He-3/H ratio in the solar photosphere from SMM gamma ray measurements

Comparisons of Solar Maximum Mission (SMM) observations of gamma-ray line and neutron emission with theoretical calculation of their expected production by flare accelerated ion interactions in the solar atmosphere have led to significant advances in the understanding of solar flare particle acceleration and interaction, as well as the flare process itself. These comparisons have enabled the determination of, not only the total number and energy spectrum of accelerated ions trapped at the sun, but also the ion angular distribution as they interact in the solar atmosphere. The Monte Carlo program was modified to include in the calculations of ion trajectories the effects of both mirroring in converging magnetic fields and of pitch angle scattering. Comparing the results of these calculations with the SMM observations, not only the angular distribution of the interacting ions can be determined, but also the initial angular distribution of the ions at acceleration. The reliable determination of the solar photospheric He-3 abundance is of great importance for understanding nucleosynthesis in the early universe and its implications for cosmology, as well as for the study of the evolution of the sun. It is also essential for the determinations of the spectrum and total number of flare accelerated ions from the SMM/GRS gamma-ray line measurements. Systematic Monte Carlo calculations of the time dependence were made as a function of the He-3 abundance and other variables. A new series of calculations were compared for the time-dependent flux of 2.223 MeV neutron capture line emission and the ratio of the time-integrated flux in the 2.223 MeV line to that in the 4.1 to 6.4 MeV nuclear deexcitation band.

Lingenfelter, Richard E.↗
NASA NTRS1984

A second chance for Solar Max

Using NASA's Tracking and Data Relay Satellite as a communications link, astronomers are able to receive scans from the Solar Maximum Mission (SMM) satellite immediately and regularly at the Goddard Space Flight Center. This major operational improvement permits the examination of SMM imagery and spectra as they arrive, as well as the formulation of future observational sequences on the basis of the solar activity in progress. Attention is given to aspects of the sun that change in the course of the 11-year sunspot cycle's movement from maximum to minimum. Proof has been obtained by means of SMM for the near-simultaneity of X-ray and UV bursts at flare onset.

Maran, S. P.↗
NASA NTRS1985

High-resolution X-ray spectra of solar flares. VII - A long-duration X-ray flare associated with a coronal mass ejection

It has been recognized that very long duration X-ray events (lasting several hours) are frequently associated with coronal mass ejection. Thus, Sheeley et al. (1983) found that the probability of the occurrence of a coronal mass ejection (CME) increases monotonically with the X-ray event duration time. It is pointed out that the association of long-duration, or long-decay, X-ray events (LDEs) with CMEs was first recognized from analysis of solar images obtained by the X-ray telescopes on Skylab and the Naval Research Laboratory (NRL) slitless spectroheliograph. Recently high-resolution Bragg crystal X-ray spectrometers have been flown on three spacecraft, including the Department of Defense P78-1 spacecraft, the NASA Solar Maximum Mission (SMM), and the Japanese Hinotori spacecraft. In the present paper, P78-1 X-ray spectra of an LDE which had its origin behind the solar west limb on November 14, 1980 is presented. The obtained data make it possible to estimate temperatures of the hottest portion of the magnetic loops in which the emission arises.

Kreplin, R. W.↗
NASA NTRS1995

Periodicities of hard x-ray burst during the last solar cycle

By using power spectrum and standard FFT time series analysis, the Hard X-ray burst during solar cycle -22 were studied. This data of Hard X-ray burst spectrometer (HXRBS) on the solar maximum mission from Launch and February 14, 1980, through re-entry on December 2, 1989, by NASA artificial satellite. The results indicate that there are short and intermediate solar periodicities. Also it is found that there is a relation between the short periodicities (few minutes) with similar periodicities in solar radio emissions and in good agreement with the theoretical mode of solar oscillations.

Hady, Ahmed A.↗
NASA NTRS1984

Microwave, soft and hard X-ray imaging observations of two solar flares

A set of microwave and hard X-ray observations of two flares observed simultaneously with the Very Large Array (VLA) and the Solar Maximum Mission Hard X-ray Imaging Spectrometer (SMM-HXIS) are presented. The LVA was used at 6 cm to map the slowly varying and burst components in three neighboring solar active regions (Boulder Nos. 2522, 2530, and 2519) from approximately 14:00 UT until 01:00 UT on June 24-25, 1980. Six microwave bursts less than 30 sfu were observed, and for the strongest of these, two-dimensional 'snapshot' (10 s) maps with spatial resolution of 5 in. were synthesized. HXIS data show clear interconnections between regions 2522 and 2530. The X-ray observations present a global picture of flaring activity, while the VLA data show the complexity of the small magnetic structures associated with the impulsive phase phenomena. It is seen that energy release did not occur in a single isolated magnetic structure, but over a large area of intermingled loop structures.

Kundu, M. R.↗
NASA NTRS1985

Solar hard X-ray bursts

The major results from the Solar Maximum Mission (SMM) are presented as they relate to our understanding of the energy release and particle transportation processes that lead to the high-energy X-ray aspects of solar flares. Evidence is reviewed for a 152-158 day periodicity in various aspects of solar activity, including the rate of occurence of hard X-ray and gamma-ray flares. The statistical properties of over 7000 hard X-ray flares detected with the Hard X-Ray Burst Spectrometer are presented, including the spectrum of peak rates and the distribution of the photon number spectrum. A flare classification scheme introduced by Tanaka is used, and characteristics of the different types (types A, B, and C) are noted. A model based on the association of type C flares and coronal mass ejections is presented to explain many of the characteristics of these gradual flares.

Dennis, B. R.↗
NASA NTRS1986

MAX '91: An advanced payload for the exploration of high energy processes on the active sun

The results of a NASA science working group established to study a follow-on to the Solar Maximum Mission are given. A complement of instruments is suggested, with the primary objective of studying the physics of energetic processes in cosmic plasmas by observing high-energy phenomena in solar flares. High-quality flare observations will be possible with these instruments during the next peak in solar activity expected to last from 1990 through at least 1995. The primary objective of MAX '91 is to study energetic processes in cosmic plasmas by observing high-energy phenomena in solar flares. These processes, which are of general astrophysical importance, include energy release, particle acceleration, and energy transport. Results from comprehensive observing programs conducted during the last solar cycle have demonstrated the great scientific potential of high-energy emissions for addressing these central physical processes. Consequently, a payload optimized for observations of high-energy solar flare phenomena is suggested for MAX '91. It consists of the following four specific instruments: (1) a Fourier-transform X-ray and gamma-ray imager covering the energy range from a few keV to 1 MeV with arcsecond spatial resolution; (2) a cooled germanium X-ray and gamma-ray spectrometer with keV spectral resolution covering the energy range from 10 keV to 50 MeV; (3) Bragg spectrometers with high spectral resolution at wavelengths between 1 and 9 angstrons; and (4) a soft X-ray, EUV, or UV imaging instrument with arcsecond spatial resolution.

Source record↗
NASA NTRS1986

Energy balance in solar active regions - The dip of April, 1985

The presence of a solar active region affects the luminosity of the sun. Sunspots directly produce 'dips' in the total solar irradiance approximately proportionally to their projected area, while faculae produce excess energy. These effects were discovered during the solar maximum period of 1980, and the sunspot effect during solar minimum is examined. The 'dip' due to an active region in April, 1985, as observed in the total solar irradiance by the ACRIM instrument on the Solar Maximum Mission is examined. These data (obtained after the spacecraft repair in May, 1984) have simple variations, relative to those observed in 1980, because of the reduced level of activity approaching solar minimum. It is found that the PSI index of projected sunspot area as defined in 1980 appears to describe this 'dip' satisfactorily.

Hudson, H. S.↗
NASA NTRS1979

Development of concepts for satellite retrieval devices

The teleoperator being developed to augment the Space Transportation System (STS) for satellite placement, retrieval, or servicing at altitudes or orbital planes where it would be impractical to use the shuttle is primarily a general purpose propulsion stage that can be fitted with manipulator arms, automated servicers and satellite retrieval devices for particular missions. Design concepts for a general purpose retrieval device for docking with a satellite to which a grappling fixture has been attached, and for a retrieval device for docking with the Solar Maximum Mission (SMM) spacecraft were defined. The mechanical aspects of these two devices are discussed as well as the crew operations involved and problems created by the requirement for remote control. Drawings for the two retrieval device concepts are included.

Pruett, E. C.↗
NASA NTRS1984

The inconstant solar constant

The Active Cavity Radiometer Irradiance Monitor (ACRIM) of the Solar Maximum Mission satellite measures the radiant power emitted by the sun in the direction of the earth and has worked flawlessly since 1980. The main motivation for ACRIM's use to measure the solar constant is the determination of the extent to which this quantity's variations affect earth weather and climate. Data from the solar minimum of 1986-1987 is eagerly anticipated, with a view to the possible presence of a solar cycle variation in addition to that caused directly by sunspots.

Willson, R. C.↗
NASA NTRS1985

Monte Carlo calibration of the SMM gamma ray spectrometer for high energy gamma rays and neutrons

The Gamma Ray Spectrometer (GRS) on the Solar Maximum Mission spacecraft was primarily designed and calibrated for nuclear gamma ray line measurements, but also has a high energy mode which allows the detection of gamma rays at energies above 10 MeV and solar neutrons above 20 MeV. The GRS response has been extrapolated until now for high energy gamma rays from an early design study employing Monte Carlo calculations. The response to 50 to 600 MeV solar neutrons was estimated from a simple model which did not consider secondary charged particles escaping into the veto shields. In view of numerous detections by the GRS of solar flares emitting high energy gamma rays, including at least two emitting directly detectable neutrons, the calibration of the high energy mode in the flight model has been recalculated by the use of more sophisticated Monte Carlo computer codes. New results presented show that the GRS response to gamma rays above 20 MeV and to neutrons above 100 MeV is significantly lower than the earlier estimates.

Cooper, J. F.↗
NASA NTRS1990

Computer graphics aid mission operations

The application of computer graphics techniques in NASA space missions is reviewed. Telemetric monitoring of the Space Shuttle and its components is discussed, noting the use of computer graphics for real-time visualization problems in the retrieval and repair of the Solar Maximum Mission. The use of the world map display for determining a spacecraft's location above the earth and the problem of verifying the relative position and orientation of spacecraft to celestial bodies are examined. The Flight Dynamics/STS Three-dimensional Monitoring System and the Trajectroy Computations and Orbital Products System world map display are described, emphasizing Space Shuttle applications. Also, consideration is given to the development of monitoring systems such as the Shuttle Payloads Mission Monitoring System and the Attitude Heads-Up Display and the use of the NASA-Goddard Two-dimensional Graphics Monitoring System during Shuttle missions and to support the Hubble Space Telescope.

Jeletic, James F.↗