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The relation of IMP-7 and IMP-8 data to the International Magnetospheric Study is discussed. Relevant spacecraft and experiment characteristics, and the nature and accessibility of data from each experiment, are identified. Finally the potential value of IMP data in IMS studies is illustrated with a few citations from the IMP Bibliography and with figures from a recent multiple-data-set magnetotail plasma sheet study.
The package design and assembly techniques for the IMP-F and IMP-G space-physics experiments, provided for the NASA Interplanetary Monitoring Platform Program are described. Thin-film, hybrid, integrated circuits used in these instruments to increase component density and reliability, and special procedures and precautions for the fabrication of space hardware are described.
The availability of a data set of IMP-J (IMP 8) field and plasma data is announced. Magnetic field data and plasma data from a Faraday cup experiment are provided.
Results and description of qualification tests of attitude control system and yo-yo despin system in flight configuration as installed on IMP-1 spacecraft
The primary data reduction effort during the reporting period was to process summary plots of the IMP 8 plasma wave data and to submit these data to the National Space Science Data Center. Features of the electrostatic noise are compared with simultaneous observations of the magnetic field, plasma and energetic electrons. Spectral characteristics of the noise and the results of this comparison both suggest that in its high frequency part at least the noise does not belong to normal modes of plasma waves but represents either quasi-thermal noise in the non-Maxwellian plasma or artificial noise generated by spacecraft interaction with the medium.
Observational data for solar X-ray flares measured by Explorer 33 and Explorer 35 satellites
Bibliography of publications and compilation of abstracts on Explorer 33 and 35 satellites
Analysis of solar flare particle measurements by Explorer 34 and 41 satellites
The DE 1 imaging instrumentation provides a full view of the entire auroral oval every 12 min for several hours during each orbit. We examined five examples of global evolution of the aurora that occurred during the northern hemisphere winter of 1981-1982 when the z component of the interplanetary magnetic field was positive and the y component was changing sign. Evolution of an expanded auroral emission region into a theta aurora appears to require a change in the sign of By during northward interplanetary magnetic field (IMF). Theta aurora are formed both from expanded duskside emission regions (By changes from positive to negative) and dawnside emission regions (By changes from negative to positive), however the dawnside-originating and duskside-originating evolutions are not mirror images. The persistence of a theta aurora after its formation suggests that there may be no clear relationship between the theta aurora pattern and the instantaneous configuration of the IMF.
The technical aspects of the University of California IMP-F experiment aboard the Explorer-34 and the University of California IMP-G (S1) and (S2) experiments aboard the Explorer-41. The experiment detectors and electronics are discussed for each experiment as well as the fabrication, preflight and post-flight history. A description of the ground support equipment is also given for each experiment. These three experiments were essentially all different. The IMP-G experiment was essentially the IMP-F experiment with the addition of four Geiger-Mueller detectors. The IMP-G (S-2) was a supplementary experiment and differed completely from the IMP-F and IMP-G experiments. It was concluded that the ground support equipment approach used for the IMP-F and IMP-G experiments where emphasis was placed on a thorough exercise and monitoring of the experiment operation during various testing phases provided a high degree of confidence and reliability in these experiments. No known electronic failures have occurred during the spacecraft lifetime although some detector problems were experienced.
243 Ida is the second asteroid target of the Galileo mission. The Infrared Astronomical Satellite (IRAS) detected Ida several times during its 1983 sky survey. The IRAS Minor Planet Survey (IMPS) yields a total of 13 usable observations during 6 sightings of Ida. These data result in a geometric visual albedo of 0.24 and a mean diameter of 28 km for Ida. The IMPS catalog updates and extends the IRAS Asteroid and Comet Survey through asteroid number 4679. File versions of IMPS final products will be available from the National Space Science Data Center (NSSDC). The input for IMPS processing includes updated visual absolute magnitudes and orbital elements for each asteroid. H and G are 9.94 and 0.15 for Ida. IMPS also includes a correction for low flux densities (less than approximately 1 Jansky). In the case of Ida, 3 observations at 12 microns, 6 at 25 microns, and 4 at 60 microns were considered acceptable for analysis. Most of these do have flux densities less than 1 Jansky with a value of approximately 5 for their estimated SNR. The 25 microns observations as plotted in the figure are consistent with the variation expected for the cross section of Ida with rotation. Ida is a main belt asteroid with an S taxonomic classification. The spectra of S asteroids tend to be dominated by pyroxene with visual albedos from 0.1 to 0.3. The IMPS average albedo of 0.24 (plus or minus 0.07) for 243 Ida is in the upper range observed for S asteroids.
The data reduction procedures and programs for analysis of the IMP F and G energetic particle flux experiments are summarized. The IMP-F experiment contained two thin-window Geiger-Mueller detectors and an ionization chamber. There were two IMP-G experiments: one with six Geiger-Mueller detectors and an ionization chamber, and the other with two funnel mouthed channeltrons in a parallel plate electrostatic analyzer. These experiments measured particles in the energy range above 20 keV (IMP-F) and above approximately 5 keV (IMP-G). A bibliography is presented of papers containing the scientific results. These data were predominantly used for the study of low energy solar particles from flares.
The Electron Isotope Spectrometers (EIS) on IMP-8 was designed to provide measurements of low energy isotopes from H to O (1 less than or equal to Z less than or equal to 8) over the energy range from approx. 2 to approx. 40 MeV/nuc, as well as low energy electrons from approx. 0.2 to approx. 6 MeV. These measurements supported studies of the acceleration and transport of energetic particles originating on the Sun, in interplanetary space, in the Galaxy, and in Earth's and Jupiter's magnetosphere. IMP-8 was launched in October 1973 and still continues to provide key particles and fields measurements from orbit about the Earth. The IMP-8 EIS continued to operate flawlessly until 8/3/92, when a partial failure was suffered in a bias supply, which reduced the ability of the instrument to measure high energy particles. The EIS was subsequently turned off in 1995. A nearly identical instrument was flown on IMP-7 from 10/92 to 7/96, and many studies combined results from both instruments. For completeness, this report summarizes scientific results and publications from the entire IMP-7&8 effort, not just from the period covered by NAG5-727.
IMP-8 (IMP-J) was launched by NASA on October 26, 1973 to measure the magnetic fields, plasmas, and energetic charged particles (e.g., cosmic rays) of the Earth's magnetotail and magnetosheath and of the near-Earth solar wind. IMP-8, the last often IMP (Interplanetary Monitoring Platform) or AIMP (Anchored-IMP) spacecraft launched in 10 years, operated until October 7, 2006, in a near-circular, 35 Earth Radii, 12-day orbit. It was an important adjunct to the International Solar Terrestrial Physics program, provided in-ecliptic, one Astronomical Unit baseline data for the deep space Pioneer, Voyager and Ulysses missions, and built a long-time-series database useful in understanding long-term solar processes .
IMPs exhibit a perplexing combination of characteristics that are consistent with either an approximately 100 Ma or 3 Ga formation. Dozens of small-area IMPs have crisp morphologies and crater size-frequency distributions (SFDs) that denote relatively recent geologic activity (less than 100 Ma); however, the apparently well-developed regolith on portions of the IMPs are in conflict with such a young age [1]. To test possible formation hypotheses (e.g., [1-5]), which range from ancient volcanism to contemporary outgassing, we examined IMP morphology at the meter-scale with LROC NAC images and derived elevation models. We focused on the largest IMPs (Ina, Sosigenes, Cauchy, Maskelyne, and Nubium), where contacts between deposits are best developed. Most of our observations are consistent with multiple generations of inflation and breakouts (or squeeze-ups) of basaltic lavas that were affected by local slopes. Some of the extrusions coalesced into larger mounds or filled pre-existing craters. We did not observe evidence of large-scale void space (e.g., fissures, fractures, linear depressions, or pits) within or beneath the mounds or rougher deposits (e.g., [5]). But, small-scale voids may be signified by isolated pitted textures. We also did not detect evidence of the cooling fractures or lava plates expected in young lava flows and observed in lunar impact melt deposits. The smooth texture of the mounds is enigmatic. Block-less craters suggest at least 5 m of friable or poorly-cohesive material (such as regolith), yet mound margins exhibit slopes greater than 30 deg requiring significant material strength. Blocks are not common on the mounds, but are sometimes excavated by impacts (usually excavated from beneath the mounds). The uneven deposits are equally enigmatic and texturally varied (blocky, pitted, and crenulated). They are deficient in superposed craters compared to the mounds. If the mounds are indeed of similar age to the rougher units, then their different superposed crater morphologies and SFDs need to be explained by factors other than their ages. Any mounds originally composed of friable surface materials would evolve differently from more coherent deposits (e.g., [6-7]).
The main characteristics of the IMP spacecraft and experiments are considered and the scientific knowledge gained is presented in the form of abstracts of scientific papers using IMP data. Spacecraft characteristics, including temporal and spatial coverages, are presented followed by an annotated bibliography. Experiments conducted on all IMP's (including prelaunch IMP's H and J) are described. Figures are presented showing the time histories, through the end of 1970, of magnetic field, plasma, and energetic particle experiments.
The corrector module of the RAEIOS program and the IMP dynamics computer program were combined to achieve a date-fitting capability with the more general spacecraft dynamics models of the IMP program. The IMP dynamics program presents models of spacecraft dynamics for satellites with long, flexible booms. The properties of the corrector are discussed and a description is presented of the performance criteria and search logic for parameter estimation. A description is also given of the modifications made to add the corrector to the IMP program. This includes subroutine descriptions, common definitions, definition of input, and a description of output.
Armstrong et al. (1978) have observed a unique series of bursts with an unusually high content of Z greater than 2 particles and a high degree of collimation from the direction of the sun. The bursts were observed only with the CPME (Charged Particle Measurement Instrument) on Imp 8, but not with the CPME on Imp 7 nor with the ULET (Ultralow Energy Telescope) on Imp 8, whose response characteristics matched those of the CPME on Imp 7. The present comparison of the measurements made with the CPME and ULET cast doubt on the correctness of the reported observations.