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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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NASA NTRS1985

Post flight analysis of NASA standard star trackers recovered from the solar maximum mission

The flight hardware returned after the Solar Maximum Mission Repair Mission was analyzed to determine the effects of 4 years in space. The NASA Standard Star Tracker would be a good candidate for such analysis because it is moderately complex and had a very elaborate calibration during the acceptance procedure. However, the recovery process extensively damaged the cathode of the image dissector detector making proper operation of the tracker and a comparison with preflight characteristics impossible. Otherwise, the tracker functioned nominally during testing.

Newman, P.↗
NASA NTRS1986

Simultaneous Solar Maximum Mission (SMM) and very large array observations of solar active regions

The research deals mainly with Very Large Array and Solar Maximum Mission observations of the ubiquitous coronal loops that dominate the structure of the low corona. As illustrated, the observations of thermal cyclotron lines at microwave wavelengths provide a powerful new method of accurately specifying the coronal magnetic field strength. Processes are delineated that trigger solar eruptions from coronal loops, including preburst heating and the magnetic interaction of coronal loops. Evidence for coherent burst mechanisms is provided for both the Sun and nearby stars, while other observations suggest the presence of currents that may amplify the coronal magnetic field to unexpectedly high levels. The existence is reported of a new class of compact, variable moving sources in regions of apparently weak photospheric field.

Lang, K. R.↗
NASA NTRS1985

Simultaneous Solar Maximum Mission and Very Large Array (VLA) observations of solar active regions

Simultaneous observations of solar active regions with the Solar Maximum Mission (SMM) Satellite and the Very Large Array (VLA) have been obtained and analyzed. Combined results enhance the scientific return for beyond that expeted from using either SMM or VLA alone. A total of two weeks of simultaneous SMM/VLA data were obtained. The multiple wavelength VLA observations were used to determine the temperature and magnetic structure at different heights within coronal loops. These data are compared with simultaneous SMM observations. Several papers on the subject are in progress. They include VLA observations of compact, transient sources in the transition region; simultaneous SMM/VLA observations of the coronal loops in one active region and the evolution of another one; and sampling of the coronal plasma using thermal cyclotron lines (magnetic field - VLA) and soft X ray spectral lines (electron density and electron temperaure-SMM).

Lang, K. R.↗
NASA NTRS1984

Coronal mass ejections observed during the solar maximum mission - Latitude distribution and rate of occurrence

Sixty-five coronal mass ejections have been identified in a systematic examination of white-light coronal images obtained between March and September 1980 by the coronagraph/polarimeter flown on the solar maximum mission spacecraft. These ejections were more uniformly distributed in position angle (or 'projected' solar latitude) than the similar events observed during the Skylab mission in 1973-1974; 27 percent of the solar maximum mission mass ejections were centered at positions more than 45 deg from the solar equator. The average rate of occurrence of the observed mass ejections for the entire solar maximum mission epoch, based on the assumption that one coronagraph image per spacecraft orbit is sufficient for detection, was 0.9 + or 0.15 per 24-hour day. Application of the same sampling assumption to the Skylab data set leads to a rate of 0.75 per 24-hour day and thus a change in this rate from the Skylab era (on the declining phase of sunspot cycle 20) to solar maximum mission (near the maximum of sunspot cycle 21) of only approximately 20 percent.

Hundhausen, A. J.↗
NASA NTRS1982

Solar flare X-ray spectra from the Solar Maximum Mission Flat Crystal Spectrometer

High-resolution solar X-ray spectra obtained with the Flat Crystal Spectrometer aboard the Solar Maximum Mission from two solar flares and a nonflaring active region are analyzed. The 1-22 A region was observed during the flare on 1980 August 25, while smaller spectral regions were repeatedly covered during the 1980 November 5 flare. Voigt profiles were fitted to spectral lines to derive accurate wavelengths and to resolve blends. During the August 25 flare, 205 lines were found in the range 5.68-18.97 A, identifications being provided for all but 40 (mostly weak) lines. Upper limits to flare densities are derived from various line ratios, the hotter (about 10 to the 7th K) ions giving an electron density of less than 10 to the 12th per cu cm for the August 25 flare. Other observed line ratios (e.g., in Fe XVII and Mg XII) indicate a need for revisions in theoretical calculations.

Phillips, K. J. H.↗
NASA NTRS1981

Studies of the corona with the Solar Maximum Mission coronagraph/polarimeter

The visible wavelength coronagraph/polarimeter on the Solar Maximum Mission (SMM) spacecraft is providing data on the flare processes manifested by coronal transients and on the degree of disruption of the evolutionary corona at the present epoch of the solar activity cycle. Among the first results are the discovery of frequent H-alpha emission from remnants of eruptive prominences in the outer corona and first observations of Fe XIV line emission to 3.2 solar radii. In the early stages of transients, cavities less dense than the ambient corona are occasionally found trailing the transient loops, with the loops being relatively thick and structureless. Some 22 transients have been identified in the initial survey of 52 days of observations; from this sample the preliminary conclusion is that transients during the SMM era (near solar maximum) occur over a wider range of latitude than, but with about the same range of speeds as, transients during the Skylab era (near solar minimum).

House, L. L.↗
NASA NTRS1982

Atmospheric ozone determination by solar occultation using the UV spectrometer on the Solar Maximum Mission

The UV spectrometer polarimeter instrument on the Solar Maximum Mission spacecraft has been used to measure ozone in the 53-75 km altitude interval by the technique of solar occultation. A 1 x 180 arcsec entrance aperture spectrometer with 0.04-A spectral resolution was employed. Resulting high-quality data are reduced by expressing measured UV attenuation as a Volterra integral equation. Solution of the equation is accomplished by expressing the integral in terms of a series representing the sum of ozone densities contained in concentric shells through tangent points separated by specified altitude increments. Sample ozone vs altitude profiles are presented for the equatorial region. These data show reproducibility to better than 10%. The density at 60 km is 7.3 + or - 0.15 x 10 to the 9th/cu cm for 2.5 deg latitude and longitudes between 81 and 105 deg west in September 1980. Density vs altitude profile exhibits changes in slope between 50 and 75 km.

Aikin, A. C.↗
NASA NTRS1986

Coordinated observations in support of the solar maximum mission

The in-orbit repair of the Solar Maximum Mission satellite has provided an opportunity to continue observations of the Sun's outer corona, transition region, and bolometric flux through the decay phase and minimum of the solar cycle. The coordinated observation of the solar photosphere, chromosphere, and low corona from the ground is a necessary companion to understanding the full range of phenomena seen over the solar cycle by the spacecraft instruments. A program of such observations has been undertaken at the Mees Solar Observatory, and has established a broad database for the analysis of the solar atmosphere and interior.

Labonte, B.↗
NASA NTRS1980

Solar Maximum Mission

The paper considers the objectives of the Solar Maximum Mission (SMM), and describes its spacecraft, the scientific planning, the observing program, and the guest investigator programs. The SMM observatory will be injected into a circular orbit with an altitude of 574 km and it is designed for a minimum of one year of operational life; its observing program is directed at the physics of solar flares, and includes studies of thermalization, the nature of electron acceleration, the flare energy budget, and the flare decay. Finally, the SMM Guest Investigator program is discussed, including ground-based synoptic and atomic data investigations and SMM data interpretation.

Bohlin, J. D.↗
NASA NTRS1978

Attitude control algorithms for the Solar Maximum Mission

Algorithms for onboard attitude control of the Solar Maximum Mission (SMM) are discussed and test results are presented. The algorithms include: despin and sun acquisition, control of pitch and yaw (sun pointing) to 5 arc-sec accuracy and roll (around the sun line) to 0.1 deg, time-optimal and constant-rate slew sequences, attitude maintenance during orbit night and sun reacquisition at orbit dawn, momentum unloading, and gyro drift calibration. The tests were performed on the SMM Software Development and Validation Facility at the NASA Goddard Space Flight Center with a FORTRAN prototype version of the onboard software.

Markley, F. L.↗
NASA NTRS1986

Ultraviolet spectrometer and polarimeter (UVSP) software development and hardware tests for the solar maximum mission

The Ultraviolet Spectrometer/Polarimeter Instrument (UVSP) for the Solar Maximum Mission (SMM) was based on the re-use of the engineering model of the high resolution ultraviolet spectrometer developed for the OSO-8 mission. Lockheed assumed four distinct responsibilities in the UVSP program: technical evaluation of the OSO-8 engineering model; technical consulting on the electronic, optical, and mechanical modifications to the OSO-8 engineering model hardware; design and development of the UVSP software system; and scientific participation in the operations and analysis phase of the mission. Lockheed also provided technical consulting and assistance with instrument hardware performance anomalies encountered during the post launch operation of the SMM observatory. An index to the quarterly reports delivered under the contract are contained, and serves as a useful capsule history of the program activity.

Bruner, M. E.↗
NASA NTRS1984

Initial results from the repaired Solar Maximum Mission and future prospects

Goals of the recently repaired Solar Maximum Mission Observatory are outlined, including continued emphasis on diagnosing impulsive phase of flares, studies of prominence and coronal plasmas, solar cycle variations of flares, the corona and solar irradiance, and comets. Some preliminary observations taken after the repair are shown, particularly of the X13 flare of April 1984.

Woodgate, B. E.↗
NASA NTRS1984

Ultraviolet observations of solar flares from the Solar Maximum Mission

The results of observations of solar flares, obtained by means of the UV Spectrophotometer and Polarimeter (UVSP) instrument on board the Solar Maximum Mission satellite are summarized and discussed. The results are grouped into three main topics: (1) plasma diagnostics in the flare transition zone plasmas, (2) spatial and temporal evolutions of the UV and hard X-ray bursts, and (3) energy release processes in the impulsive phase. The methods of spectral UV analysis, comparison with the hard X-ray burst results, and the interpretation of the results are summarized. It is concluded that the energy release processes in the flare phase can be best interpreted in terms of multiple large and small interloops interacting with each other either mechanically or inductively. Furthermore, the majority of impulsive UV and hard X-ray bursts occurs in small compact loops with high densities and transition-zone temperatures. The impulsive hard X-ray and UV bursts are emitted by nonthermal particles, accelerated by the loop interactions and impinging on the footpoints of these loops.

Cheng, C.-C.↗
NASA NTRS1980

The Ultraviolet Spectrometer and Polarimeter on the Solar Maximum Mission

The Ultraviolet Spectrometer and Polarimeter (UVSP) on the Solar Maximum Mission spacecraft is described, including the experiment objectives, system design, performance, and modes of operation. The instrument operates in the wavelength range 1150-3600 A with better than 2 arcsec spatial resolution, raster range 256 x 256 sq arcsec, and 20 mA spectral resolution in second order. Observations can be made with specific sets of four lines simultaneously, or with both sides of two lines simultaneously for velocity and polarization. A rotatable retarder can be inserted into the spectrometer beam for measurement of Zeeman splitting and linear polarization in the transition region and chromosphere.

Woodgate, B. E.↗
NASA NTRS1991

The 1980 solar maximum mission event listing

Information is contained on solar burst and transient activity observed by the Solar Maximum Mission (SMM) during 1980 pointed observations. Data from the following SMM experiments are included: (1) Gamma Ray Spectrometer, (2) Hard X-Ray Burst Spectrometer, (3) Hard X-Ray Imaging Spectrometer, (4) Flat Crystal Spectrometer, (5) Bent Crystal Spectrometer, (6) Ultraviolet Spectrometer and Polarimeter, and (7) Coronagraph/Polarimeter. Correlative optical, radio, and Geostationary Operational Environmental Satellite (GOES) x ray data are also presented. Where possible, bursts or transients observed in the various wavelengths were grouped into discrete flare events identified by unique event numbers. Each event carries a qualifier denoting the quality or completeness of the observations. Spacecraft pointing coordinates and flare site angular displacement values from Sun center are also included.

Speich, D. M.↗
NASA NTRS1991

Simultaneous Solar Maximum Mission (SMM) and Very Large Array (VLA) observations of solar active regions

Very Large Array observations at 20 cm wavelength can detect the hot coronal plasma previously observed at soft x ray wavelengths. Thermal cyclotron line emission was detected at the apex of coronal loops where the magnetic field strength is relatively constant. Detailed comparison of simultaneous Solar Maximum Mission (SMM) Satellite and VLA data indicate that physical parameters such as electron temperature, electron density, and magnetic field strength can be obtained, but that some coronal loops remain invisible in either spectral domain. The unprecedent spatial resolution of the VLA at 20 cm wavelength showed that the precursor, impulsive, and post-flare components of solar bursts originate in nearby, but separate loops or systems of loops.. In some cases preburst heating and magnetic changes are observed from loops tens of minutes prior to the impulsive phase. Comparisons with soft x ray images and spectra and with hard x ray data specify the magnetic field strength and emission mechanism of flaring coronal loops. At the longer 91 cm wavelength, the VLA detected extensive emission interpreted as a hot 10(exp 5) K interface between cool, dense H alpha filaments and the surrounding hotter, rarefield corona. Observations at 91 cm also provide evidence for time-correlated bursts in active regions on opposite sides of the solar equator; they are attributed to flare triggering by relativistic particles that move along large-scale, otherwise-invisible, magnetic conduits that link active regions in opposite hemispheres of the Sun.

Willson, Robert F.↗
NASA NTRS1982

Solar array system for solar maximum mission

The paper describes the design of the solar array system (SAS) for the Solar Maximum Mission, the unique features of the SAS, and the results of its successful in-orbit operation. It is noted that the array was unique in that: (1) major weight concessions were made to produce a dynamically stiff array; (2) it was the first array designed to be compatible with the NASA Multimission Modular Spacecraft; (3) it is the first jettisonable solar array; and (4) it represents the first use of FEP-bonded overslides on a prime power array. It is concluded that the array performed as predicted with no evidence of the FEP causing any unusual array power degradations. In addition, the deployment and telemetry systems performed as designed.

Meese, R. A.↗
NASA NTRS1981

Control of the Soft X-ray Polychromator on the Solar Maximum Mission Satellite

The Soft X-ray Polychromator on the Solar Maximum Mission Satellite consists of two largely independent instruments: the Flat Crystal Spectrometer, a highly collimated scanning spectrometer mounted on a raster platform, and the Bent Crystal Spectrometer, a broadly collimated spectrometer providing high time-resolution (128 ms) spectra for the study of rapidly evolving phenomena. Each instrument is controlled by a microcomputer system built around an RCA 1802 microprocessor. This paper presents a discussion of the motivation for using a microprocessor in this application, and the design concepts that were implemented. The effectiveness of the approach as seen after several months of operation will also be discussed.

Springer, L. A.↗