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One of the oldest mysteries in geomagnetism is the linkage between solar and geomagnetic activity. In investigating the causes of geomagnetic storms occurring during solar maximum, the following topics are discussed: solar phenomena; types of solar wind; magnetic reconnection and magnetic storms; an interplanetary example; and future space physics missions.
A projected inner zone electron model environment, AE 6, for the epoch 1980 is presented. It is intended to provide estimates of mission fluxes that spacecraft will encounter in the coming solar maximum years. AE 6 is presented by graphs of omnidirectional integral flux as a function of L shell, the ambient magnetic field B, and the energy E. Results of orbital integrations for altitudes from 150 n.m. to 18,000 n.m. are given for circular orbits with four different inclinations, using the AE 6 and the AE 4 solar maximum models for the inner and outer zones, respectively. The derivation of AE 6 is described, and a brief comparison is given of the radial profiles of equatorial fluxes from several related models. A short summary of the associated computer programs is included.
Polar aurorae in Jupiter's atmosphere radiate throughout the electromagnetic spectrum from X ray through mid-infrared (mid-IR, 5 - 20 micron wavelength). Voyager IRIS data and ground-based spectroscopic measurements of Jupiter's northern mid-IR aurora, acquired since 1982, reveal a correlation between auroral brightness and solar activity that has not been observed in Jovian aurora at other wavelengths. Over nearly three solar cycles, Jupiter auroral ethane emission brightness and solar 10.7 cm radio flux and sunspot number are positively correlated with high confidence. Ethane line emission intensity varies over tenfold between low and high solar activity periods. Detailed measurements have been made using the GSFC HIPWAC spectrometer at the NASA IRTF since the last solar maximum, following the mid-IR emission through the declining phase toward solar minimum. An even more convincing correlation with solar activity is evident in these data. Current analyses of these results will be described, including planned measurements on polar ethane line emission scheduled through the rise of the next solar maximum beginning in 2009, with a steep gradient to a maximum in 2012. This work is relevant to the Juno mission and to the development of the Europa Jupiter System Mission. Results of observations at the Infrared Telescope Facility (IRTF) operated by the University of Hawaii under Cooperative Agreement no. NCC5-538 with the National Aeronautics and Space Administration, Science Mission Directorate, Planetary Astronomy Program. This work was supported by the NASA Planetary Astronomy Program.
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.
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.
This document contains information on solar burst and transient activity observed by the Solar Maximum Mission (SMM) during 1989 pointed observations. Data from the following SMM experiments are included: (1) Gamma Ray Spectrometer, (2) Hard X-Ray Burst Spectrometer, (3) Flat Crystal Spectrometer, (4) Bent Crystal Spectrometer, (5) Ultraviolet Spectrometer Polarimeter, and (6) Coronagraph/Polarimeter. Correlative optical, radio, and Geostationary Operational 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.
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.
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.
The Galileo Ultravilet Spectrometer Experiment (UVS) obtained a partial celestial sphere map of interplanetary Lyman-alpha (IP L alpha) on 13-14 December 1990 during the first Earth encounter. The Galileo spacecraft was near the downwind axis of the local interstellar medium flow. These UVS measurements sampled the downwind, anti-sunward hemisphere. The data were modeled using a hot model of the interplanetary hydrogen density distribution with the goal of studying multiple scattering effects in the inner solar system. The derived ratio in the downwind direction of the observed brightness and a single scattering model brightness, both normalized to unity in the upwind direction, is 1.82 +/- 0.2. This brightness ratio requires a multiple scattering correction which is 36% larger than can be accounted for by theoretical calculations. The hot model may require: (1) a temperature perturbation of the interstellar wind velocity distribution or (2) an additional downstream source of interplanetary hydrogen. However, a more likely exlanation which affects the hot model is the latitude dependence of the radiation pressure. This dependence, based on the known solar L alpha flux latitude variation at solar maximum, causes a downwind brightness enhancement by preferential focusing of H-atoms with trajectory planes containing the solar poles. This result implies that radiation pressure near the solar poles is nearly independent of solar cycle and is insufficient to lead to a net repulsion of hydrogen atoms by the sun, as can occur near the ecliptic plane during the solar maximum. In addition, the UVS performed 13 observations of IP L alpha while in cruise between Venus and the Earth in 3 directions fixed in ecliptic coordinates.
The UV spectrometer polarimeter on the Solar Maximum Mission has been utilized to measure mesospheric O3 altitude profiles by the technique of solar occultation. Sunset data are presented for 1980, during the fall equinoctal period within + or - 20 deg of the geographic equator. Mean O3 concentrations are (40, 16, 5.5, and 1.5) x 10 to the 9th/cu cm at 50, 55, 60, and 65 km, respectively. Some profiles exhibit altitude structure which is wavelike. The mean O3 profile is fit best with the results of a time-dependent model if the assumed water-vapor mixing ratio employed varies from 6 ppm at 65 km.
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.
The following topics are covered in viewgraph format: Solar Maximum Mission (SSM) background; battery background and specifications; and battery rundown tests.
The on-orbit repair sequence of the Solar Maximum Mission in April 1984 is described, and important lessons learned concerning orbital debris are summarized. Scientific results pertaining to a solar flare which occurred just before the repair are reviewed. The implications of the repair experience for serviceability in the design of future spacecraft and instruments are illustrated by the case of the Hubble Space Telescope and its second generation spectrograph.
The major activities (through 15 November l987) of the Solar Maximum Mission Gamma-Ray Spectrometer (SMM GRS) team members at the University of New Hampshire and the Naval Research Laboratory and the work of the Guest Investigators since the last Semi-Annual Report are summarized. In addition, an updated list of published papers and invited papers or papers presented at scientific meetings is provided.
The Gamma Ray Experiment (GRE) is one of the seven instruments on the Solar Maximum Mission. The scientific objective of the GRE is to study solar gamma ray emissions expected during, and, according to some solar models, prior to solar flares. The instrument consists of a detector assembly and a remote electronic assembly. The latter includes redundant low-voltage power supplies and the remaining command, data handling, and ancillary electronic subsystems of the instrument. The electronic systems and subsystems of the instrument are described in some detail.
Observations by the Gamma-Ray Spectrometer (GRS) on the Solar Maximum Mission (SMM) are examined. This detector system is sensitive to high-energy X-rays, gamma-rays, and energetic neutrons. These neutral quanta provide a probe of the highest energy processes in a flare. The GRS has recorded over 150 flares since launch. In addition to the solar discoveries, the SMM GRS has made important discoveries about cosmic gamma-ray sources. These discoveries are summarized.
An earlier heuristic study of the fine attitude sensors for the Solar Maximum Mission (SMM) revealed a temperature dependence of the alignment about the yaw axis of the pair of fixed-head star trackers relative to the fine pointing Sun sensor. Here, new sensor alignment algorithms which better quantify the dependence of the alignments on the temperature are developed and applied to the SMM data. Comparison with the results from the previous study reveals the limitations of the heuristic approach. In addition, some of the basic assumptions made in the prelaunch analysis of the alignments of the SMM are examined. The results of this work have important consequences for future missions with stringent attitude requirements and where misalignment variations due to variations in the temperature will be significant.
An examination of the transition level at which the ionospheric ions O(+) and H(+) are equal in concentration has been carried out by using the retarding potential analyzer data from the OGO 6 satellite. Between dip latitudes of 0 and 50 deg the transition level shows a much more pronounced latitude dependence during solar maximum than during solar minimum. The longitude dependence of the transition level features indicates the roles that zonal and meridional F region winds might play in the distribution of O(+) and H(+) in the low- and mid-latitude ionosphere.