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Voyager Documentation

Voyager lecp data, university of maryland space physics group, - heliopause watch -.

THE LOW ENERGY CHARGED PARTICLE (LECP) EXPERIMENT ON THE VOYAGER SPACECRAFT Copyright © 1977 Kluwer Academic Publishers, Dordrecht, Boston, London . Reprinted with permission of Kluwer Academic Publishers.

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THE LOW ENERGY CHARGED PARTICLE (LECP) EXPERIMENT ON THE VOYAGER SPACECRAFT

S. M. KRIMIGIS

The Johns Hopkins University, Applied Physics Laboratory, Laurel, Md 20810 , U.S.A.

T. P. ARMSTRONG

Department of Physics, University of Kansas, Lawrence, Kansas 66044 , U.S.A.

W. I. AXFORD

Max-Planck Institute for Aeronomy, D- 3411 Katlenburg- Lindau 3, West Germany

C. O. BOSTROM

Department of Physics, University of Arizona, Tucson, Arizona 85721 , U.S.A.

G. GLOECKLER

Department of Physics & Astronomy, University of Maryland, College Park, Md 20742 , U.S.A.

L. J. LANZEROTTI

Bell Laboratories, Murray Hill, New Jersey 07904 , U.S.A.

(Received 24 May, 1977)

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1. Introduction

According to the best available estimates the solar wind extends as a supersonic flow to a heliocentric distance of the order of 50 AU or more, i.e., beyond the orbits of Neptune and Pluto (Axford, 1972) . Thus the solar wind must interact with the magnetospheres of all the planets or with their atmospheres or surfaces in cases where the planets have no internal magnetic field. Furthermore, the solar wind must interact with the satellites of any planets which are not shielded by planetary magnetospheres.

The study of the physics of planetary magnetospheres is of considerable scientific interest in itself (Kennel, 1973) . It is also of great importance in furthering our understanding of certain astronomical objects (notably pulsars and compact X-ray sources), the origin of satellites of the outer planets, and perhaps the origin of the Solar System itself (e.g., Cameron, 1973 ; Alfvén and Arrhenius, 1976 ). The existence of planetary magnetospheres presents opportunities for making direct in-situ observations of particle acceleration mechanisms, thereby leading to the possibility of achieving a better understanding of solar flare processes, cosmic ray acceleration processes, and processes in the Earth's magnetosphere. In the case of the Jovian satellite Io (and possibly other planetary satellites) there is an apparent strong interaction with the magnetosphere of the parent planet which induces intense radio emissions by mechanisms which although not well understood at present, could be of importance for understanding other astrophysical radio sources. In addition there is some evidence that planetary magnetospheres can play an important role in determining the surface structure of satellites (Mendis and Axford, 1974) .

To date spacecraft launched from Earth have probed the environment around five of the nine planets in the Solar System. Spacecraft instrumentation has also investigated various aspects of the satellites of Earth, Mars and Jupiter. The nature of the Earth's magnetosphere has been investigated in considerable detail and a rather good morphological understanding of the phenomena that can occur has been obtained. Yet, understanding in depth of many detailed plasma processes remains elusive (Williams, 1975) . The interaction of the solar wind with the Earth's moon has been investigated extensively; this interaction is a clear case of the impinging of the solar wind plasma on an essentially non-conducting and non-magnetized body that does not have an atmosphere. The bow shock and magnetic tail of the Mercurian magnetosphere have been detected and it has been observed that electron acceleration seems to occur even in this relatively simple case where there are no complications induced by the presence of a planetary atmosphere or ionosphere (Ness et al. , 1975) . The magnetosphere situations around both Mars and Venus are somewhat unclear at the present time: there appear to be bow shocks and plasma tails associated with each planet and there is also some evidence for a Martian magnetic field of internal origin (Dolginov et al. , 1972) .

Of the giant planets, the Jovian magnetosphere has been examined during flybys of Pioneer 10 and 11. It is now well documented that for this planet (a) there are pronounced magnetic field effects associated with the rotation of the planet (Smith et al. , 1974) ; (b) relativistic electrons are present with unexpectedly high fluxes (Fillius and McIlwain, 1974) ; (c) the Galilean satellites play a significant role in absorbing and perhaps accelerating particles (Fillius and McIlwain, 1974) ; and (d) energetic particles are injected by the planet into the interplanetary medium (Chenette et al. , 1974) where they can be detected even at the orbit of the Earth (Krimigis et al. , 1975b) . No spacecraft has visited Saturn as yet, but radio emissions from this planet have now been observed (Brown, 1975) so that a Saturnian magnetosphere undoubtedly exists. A unique characteristic of that magnetosphere will be the interaction of energetic particles with Saturn's rings and composition changes or 'sputtering' therefrom.

The planet Uranus will undoubtedly present an essentially new kind of magnetosphere that may well demonstrate some remarkable features. The spin axis of the planet lies essentially in the ecliptic plane and at the time of the expected Voyager encounter in 1986 the axis of rotation of the planet will be pointing at the Sun to within a few degrees (Alexander, 1965) . If the axis of rotation and the axis of the dipole component of the magnetic field are roughly coincident (as for the Earth and Jupiter), then the spacecraft will encounter, pole-onward, a rapidly rotating magnetosphere which is lying on its side (e.g., Siscoe, 1975 ).

The flyby encounters with Jupiter, Saturn and possibly Uranus, although of paramount importance in the design considerations for the LECP, will account for only a few percent of the total time duration of the Voyager mission. Prior to the Jovian encounter, between the Jovian and the Saturnian encounters, and after the Saturnian encounter there exists the opportunity to explore in depth the interplanetary medium at great distances from the Sun. Furthermore, since the two Voyager spacecraft will be in the same region of the Solar System, there will be a unique opportunity for making important correlated measurements among two spacecraft with identical instrumentation in the most distant parts of the heliosphere. Finally, the Voyager spacecraft will be travelling away from the Sun in the general direction of the postulated solar apex.

From the point of view of charged particle observations the Voyager mission and the LECP will make it possible to measure the energy spectra and composition of galactic cosmic rays in a region of space where the effects of solar modulation can be expected to be substantially less than those ever probed previously. The most important interplanetary energetic particle measurements made by LECP will be those investigating: (1) the spectra of the various atomic species comprising the galactic cosmic radiation, especially at low energies; (2) time variations of galactic cosmic rays (including Forbush decreases); (3) the radial gradient of galactic cosmic rays; (4) energetic particles of solar origin associated with flares and active regions; (5) energetic particles of planetary origin such as those observed to be associated with Jupiter as well as the Earth (Krimigis et al. , 1975a) ; and (6) energetic particles associated with interplanetary forward-reverse shock pairs (Smith and Wolfe, 1976) . In addition to providing detailed energy spectra, the detector system will make highly accurate measurements of the anisotropies of low energy cosmic rays and other energetic particles, since such anisotropies can provide a means of identifying the origins of the particles as well as shedding further light on the physics of interplanetary propagation processes.

lecp voyager

2. Scientific Objectives and Background

The Voyager mission represents a unique opportunity to perform exploratory measurements at Saturn and probably Uranus, in the outer extremes of the interplanetary medium and (possibly) in the interstellar medium, and to conduct 'second generation' studies of the Jovian environment. The LECP instrument is designed to address the following objectives:

(1) Investigate the existence, spatial extent and dynamical morphology of Saturnian and Uranian magnetospheres and measure the spectral and angular distributions, composition and plasma flows of particles in the radiation belts, bow shock, transition region and magnetotail; determine the planetary and satellite magnetic moments and the nature of nonthermal radio emission.

(2)Investigate the quasi-steady energetic particle flux in interplanetary space for studying solar modulation mechanisms, the radial gradient and radial scale of modulation, short term modulation effects, the solar, galactic, and planetary components, and particle acceleration mechanisms in the interplanetary medium, and (possibly) the terminus of the heliosphere.

(3) Perform 'second generation' studies of the composition, energy spectrum, azimuthal and pitch angle distribution of Jovian magnetospheric charged particles bearing on questions of origin, transport, loss, and of sources of decameter and decimeter radio emission, including important satellite sweeping and source effects.

(4) Study the energetic particle environments of natural planetary satellites and deduce satellite magnetic moments, conductivities, and the electrodynamics of the interaction with the planetary magnetospheres (e.g., particle 'shadowing' studies and searches for field aligned particle currents).

(5) Make inferences concerning the origin and interstellar propagation of galactic cosmic rays, their confinement times and path length distributions, by measuring the elemental and isotopic composition and anisotropy of galactic particles after the Saturnian (Uranian) encounter.

(6) Study the propagation in the distant interplanetary medium of particles emitted at the Sun by investigating their intensity-time profiles, energy spectra, gradients, and anisotropies and the charge and isotope composition.

(7) Investigate large and small scale magnetic structures in the interplanetary medium and near planets using charged particle angular distributions in order to augment magnetometer measurements.

Because of space limitations, it is not possible to give an adequate discussion of the science background for all the objectives enumerated above. Thus we will limit our remarks to a few specific points which are illustrative of the measurement and interpretive possibilities utilizing the LECP data.

A. PLANETARY MAGNETOSPHERES

The first and most important objective here is the establishment of the morphology of the magnetospheres of Saturn and Uranus. Aside from this general objective, however, our experiment is especially designed to address specific problems within the magnetospheres of both planets, and of Jupiter as well. First we expect to obtain the three- dimensional distribution function of low energy electrons and ions, which is an essential tool in the study of wave-particle interactions and the underlying physical processes which give rise to plasma instabilities in planetary magnetospheres (e.g., Williams and Lyons, 1974 ). In addition we will obtain the compositional signature of energetic ions and thus be able to infer their sources, i.e., whether these ions originate in the solar wind, planetary ionosphere, or are 'sputtered' off planetary satellites, as appears to be the case at the orbit of Io (Brown, 1973) . Further, the experiment is designed to make detailed angular distribution measurements while the spacecraft is traversing the Io flux tube at a distance of ~10 satellite radii. During this passage, the importance of Io as both a source and sink of energetic particles will be determined in a rather comprehensive manner. The implications of this measurement on the Io- associated decametric radio emissions is evident.

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B. ENERGETIC PARTICLE MEASUREMENTS IN THE INTERPLANETARY MEDIUM

The recent reports of observations of solar particle events with long- lasting anisotropies, together with the measurements of very small cosmic ray radial gradients by Pioneer 10 and 11 instruments have raised several interesting and important questions about the underlying theoretical considerations of both the modulation and energy loss of galactic cosmic rays in the Solar System as well as of the size of the solar modulation region. In addition, the important recent discoveries of planetary particle contributions to the interplanetary particle fluxes ( Teegarden et al. , 1974 ; Chenette et al. , 1974 ; Krimigis et al. , 1975a ) and the anomalous abundance of low energy C and O nuclei (Klecker et al. , 1975) reveal a situation considerably more complex than the hypothesis that all low energy cosmic rays observed near 1 AU result from the energy losses of low energy galactic particles entering the solar modulation region (Fisk et al. , 1974) .

The degree of our understanding of cosmic-ray propagation in the heliosphere can be measured by the consistency of our explanation of particles streaming (a) from the Sun (b) from planetary magnetospheres and (c) from the galaxy. The persistent anisotropies of solar flare particles of energies 1-10 3 MeV ( Roelof and Krimigis, 1973 ; Innanen and Van Allen, 1973 ; Duggal and Pomerantz, 1973 ; Wibberenz et al. , 1976 ), the very small values of the radial cosmic-ray gradients out to 5 AU (Thomsen and Van Allen, 1976) and the appearance of Jovian magnetospheric particles near Earth ( Krimigis et al. , 1975b) all seem to indicate that the region of the Solar System within ~5 AU is characterized by relatively weak scattering of cosmic rays. If so, then the control of the 11-year solar modulation of cosmic ray intensity must lie in the region beyond 5 AU (unless the modulation and scattering mechanism is not at all adequately understood). Because of the possibly large extent of the modulation region (Axford, 1972) and because the cosmic ray radial gradient at any given energy is unlikely to be uniform as a function of heliocentric distance, our instruments on the two Voyager spacecraft will allow gradient measurements at points separated by relatively short distances (i.e., a few AU), as well as between instruments at large heliocentric distances and at the orbit of Earth.

C. SOLAR AND PLANETARY PARTICLES AS PROBES OF THE INTERPLANETARY MEDIUM

Solar energetic particle events provide valuable diagnostics of the large and small scale interplanetary plasma and magnetic field at large heliocentric distances. The sensitivity of a traditional tool used for solar event analyses, i.e., study of the velocity dispersion of event onsets, increases approximately as the square of the heliocentric radius for field-aligned propagation. Hence the persistence at large heliocentric distances of an anti-sunward field- aligned anisotropy as well as the development of a 'back-scattered' flux in the sunward direction will provide important diagnostics (even more sensitive than at 1 AU) on small scale magnetic irregularity structures inside and outside (respectively) the orbit of the spacecraft. The ability of the LECP to cleanly separate atomic species and isotopes during solar events will allow an analysis of Z /A propagation effects in the outer solar system.

In addition, both the Earth and Jupiter are sources (albeit of widely differing strengths) of low energy interplanetary particles with spectral, temporal and abundance signatures distinguishable from solar events. Consequently, planetary magnetospheres can also provide particles as 'tracers' of the large scale interplanetary field, at large distances, both upstream and down stream of the planet. LECP will provide the necessary energy, abundance, and anisotropy data to make strong use of these tracers.

Finally, interplanetary acceleration of energetic particles has been observed to occur both at 1 AU and in the outer Solar System. Three main mechanisms have been discussed in the literature with regard to particle acceleration (or deceleration) in the interplanetary medium; shock-associated acceleration (essentially in the shock electric field); adiabatic deceleration (essentially a gas- dynamic cooling due to expansion); and in-situ acceleration (supposedly a second-order Fermi process).

A critical evaluation of the two basic classes of particle shock- acceleration models (microscopic plasma dynamics and post-shock magnetic field) will be possible using our LECP anisotropy and spectral measurements of electrons and ions since the post-shock regions in the outer solar system will often differ substantially from those at 1 AU. The composition dependence of the shock effects (e.g., Armstrong and Krimigis, 1973 ) is of great interest under the shock conditions at large heliocentric distances.

Adiabatic deceleration occurs when particles are effectively 'convected' by the solar wind due to efficient scattering. Our LECP anisotropy and energy spectrum data will permit us to evaluate the possible importance of this process in the outer solar system.

3. Description of Instrumentation

Measurements fulfilling the requirements of the comprehensive investigation objectives described in the previous sections cannot be conducted with a single charged particle sensor. To attain the lowest energy of response over a wide variety of particle species and with appropriate geometry factors and angular resolution, the LECP utilizes two distinct all solid-state detector configurations each of which is optimized for a particular energy-intensity range and/or group of particle species. This procedure has the additional important advantage of providing overall experimental redundancy. The two detector subsystems designated as (a) The Low Energy Magnetospheric Particle Analyzer (LEMPA) and (b) The Low Energy Particle Telescope (LEPT) are described in the next two subsections. A picture of the flight instrument is shown in Figure 2 . Both of these detector subsystems use multi-parameter detection techniques to provide measurements in over-lapping energy and intensity ranges; this redundancy increases system reliability and reduces background. Although the individual subsystems are optimized for either the interplanetary or magnetospheric environments, both subsystems will contribute substantial measurements which are important to both environments (Figure 8) . The sun-shield used for both subsystems provides an additional unique and important function in that we are able to unambiguously determine the background counting rates for all system detectors and channels in both environments. Also, small radioactive sources for inflight calibration are mounted on the sunshield. Since the detector design was done prior to the Pioneer 10 encounter of Jupiter, certain changes were necessitated following the publication of the Pioneer results. The most important of these changes was the addition of substantial shielding to appropriate detector subsystems.

A. LOW ENERGY MAGNETOSPHERIC PARTICLE ANALYZER (LEMPA) SUBSYSTEM

The detectors in the LEMPA subsystem are designed for low energy thresholds (10-15 keV), clean separation of ions from electrons, good sensitivity, and large (~10 11 ) dynamic range.

A schematic diagram of the detector arrangement in the LEMPA subsystem is shown in Figure 3 . The functions of each detector are as follows:

[alpha]

B. LOW ENERGY CHARGED PARTICLE TELESCOPE (LEPT) SUBSYSTEM

The LEPT subsystem is an array of solid state detectors designed to measure the charge and energy distributions of low and medium energy nuclei in environments where the intensity is expected to be relatively low (e.g., outer regions of planetary magnetospheres and the interplanetary and (possibly) interstellar mediums). The detector arrangement is shown schematically in Figure 5 , and consists of two multi- d E /d x x E systems placed back to back in order to use a common all solid-state active anticoincidence shield.

[DELTA]

Detectors A1 - A8 These detectors define an anticoincidence cylinder and have typical dimensions of 2.3 cm x 6 cm x 1 mm. Such detectors are highly preferable to scintillator-photomultiplier combinations for anticoincidence logic. Each pair of detectors has a separate preamplifier-amplifier chain and can be commanded off separately. By connecting two pairs of detector outputs together, two separate measurements of the omnidirectional penetrating particle rate are obtained. Detectors A1-A4 are fed into a common discriminator as are A5-A8; thus, the coincidence rate between the two (independent) halves of the anticoincidence cup is relatively free of the background induced by the onboard RTG power supply.

Detectors D3 and D4 These detectors are used in a d E /d x vs E combination to extend the energy range of the telescope from ~4 to ~40 MeV/nucleon. Both detectors are 2450 µ thick, 8.5 cm 2 lithium drifted detectors which serve as total E sensors. The signals from both D3 and D4 are log-amplified and fed into threshold discriminators and pulse-height analyzers, in the same manner as in the case of the D1, D2 and D5 detectors. Both are in anticoincidence with the 8 A detectors, to insure appropriate particle angular response and energy definition as well as to minimize background.

lecp voyager

Priority Scheme As noted above, it is not possible to transmit more than 1 or 2 pulse- height analyzed events/second due to bit-rate limitations. Incorporated in the system logic is a rotating three-level priority scheme which is based upon particle Z (atomic number). Group I contains channels responding to heavy nuclei and have the highest priority in pulse height analysis; Group II contains channels of light and medium nuclei (second priority), while Group III includes those channels responding to protons and alpha particles (third priority). To insure, however, that all groups are equally represented in environments with relatively intense fluxes of all species, the priority is rotated according to the event read out last. If the last event belonged to Group I then, after readout, Group II has the highest priority and Group III will be intermediate; if the event read out last belonged in Group II, then Group III would have the highest priority and I will be intermediate; finally, if the event read out was in Group III, then Group I will have the highest priority and Group II will be intermediate. In this manner, equal statistical weight will be obtained for all particle species in relatively intense environments. This is particularly important in the distant magnetosphere of Jupiter where large fluxes of low energy ions are expected to be present.

Geometric Factors The geometric factor for D1D2D3 events is ~0.48 cm 2 sr - 1 , while that for D2D3D4 events is ~2.3 cm 2 sr - 1 and that for D5D4A events is ~1.7 cm 2 sr -1 . For penetrating particles (D3D4A) the geometric factor is ~4 cm 2 sr -1 . The characteristics of the LEPT system are summarized in Table I . The energy coverage for both the LEPT and LEMPA subsystems is shown in Figure 7 .

Command and Data System (CDS) The CDS is a major electronic subsystem of the LECP instrument which performs a large number of processing, storage, control, timing and interface functions. These functions are described very briefly below.

The CDS accepts 42 LEPT discriminators, 33 LEMPA discriminators, and 5 coincidence strobes and generates 88 rate channels according to a set of logic equations. Rate data are accumulated in sixty-two 24- bit scalers allowing 100% duty cycle for nearly all channels. The accumulators are read in groups of four 10-bit (log-compressed) words according to one of several programs in the spacecraft Flight Data System (FDS). The rate logic is also used in the priority system to select and identify LEPT events for Pulse Height Analysis. The CDS activates the PHA system and stores four 8-bit pulse heights and an 8- bit ID code. The 40-bit PHA 'events' are sampled by FDS command. The mode and state of the instrument are controlled by four 12-bit command words (2-bits ID, 10-bits control).The interface with the spacecraft for receipt of digital command words and for data output is fully redundant.

Modes of Operation The measurements using the detector system described in the preceding sections are to be performed in two environments, i.e., the magnetospheres of Jupiter, Saturn and Uranus and the interplanetary medium. The magnetospheres can be further subdivided into the distant magnetosphere (bow shock, magnetopause, tail) and near magnetosphere (trapped radiation belts). We thus utilize three modes of operation to obtain optimum science coverage:

(2) Far Encounter Mode-Jupiter, Saturn and Uranus - Sixty days prior to closest approach to the planet the stepping platform rate is increased to 1 revolution per minute. The experiment bit rate increases to 600 bps. At this time we allocate 1/3 of the bits to PHA data and 2/3 to rate data.

To insure that valuable continuity in the data between LEPT and LEMPA is maintained, provisions have been made to sample each of the two subsystems on a 50% duty cycle between the Far Encounter and Near Encounter modes. This will be particularly valuable in the encounters of Saturn and Uranus, where long communication times and a totally unknown environment could compromise the measurements in any one mode.

The description of the LECP instrument in this paper has emphasized the physical description of the detectors and their applicability to various environments. A detailed description of most of the electronic subsystems is given in the paper by Peletier et al. (1977) .

The experiment described here satisfies all major scientific and measurement objectives in the area of low energy charged particle investigations for both environments of interest, i.e., planetary magnetospheres and the interplanetary medium. The extremely large dynamic range (~10 -5 to >10 12 cm -2 sec - 1 sr -1 ) combined with wide coverage in energy and species assures that sufficient information will be available to characterize almost any energetic particle environment encountered by the Voyager spacecraft in a comprehensive manner. 'Second generation' studies of the Jovian magnetosphere are assured at energies, intensities, and species not available with Pioneer 10 and 11 investigations. Some of the measurements will be performed for the first time in any planetary magnetosphere (including Earth's), e.g., detailed measurements of the charge composition of trapped radiation and the full particle distribution function in three dimensions. The time resolution of the measurements (as small as ~60 millisec) rival those obtained in any of several Earth-orbiting spacecraft. Finally, the multiplicity of detectors coupled with built-in redundancy of key subsystems (e.g., redundant PHA's, data output lines, etc.) assures a high degree of reliability for the whole experiment.

Acknowledgements

We wish to express our most sincere appreciation to Messrs D. P. Peletier, S. A. Gary, R. G. King, J. W. Kohl, D. E. Fort, J. T. Mueller, J. H. Crawford, R. E. Thompson, Dr. E. P. Keath and many others at JHU/APL for their tremendous enthusiasm and the many long hours that went into making the LECP experiment a success. Thanks are also due to J. Cain, E. Tums and many others at the University of Maryland, and C. G. Maclennan of Bell Laboratories for their contributions to this program. In addition, we wish to thank the JPL cognizant engineer D. E. Griffith, cognizant scientist E. Franzgrote, Messrs. G. L. Reisdorf, W. G. Fawcett, H. M. Schurmeier, J. R. Casani, J. E. Long and Dr. E. C. Stone of Cal Tech for their assistance and cooperation during the course of this work. We thank personnel at the Rutgers/Bell Tandem Van-de-Graaff accelerator (supported in part by NSF) for their generous help during calibrations. We also express our appreciation to Mr. S. K. Brown at GSFC for his dedicated help in performing LEMPA calibrations. The LECP experiment was supported by the Office of Lunar and Planetary Programs at NASA Headquarters under Task I of Contract N00017-72-C-4401 between The Johns Hopkins University and the Department of the Navy. We thank Dr. M. A. Mitz and Messrs A. Reetz, Jr., J. W. Keller and R. A. Mills of NASA Headquarters for their support during various phases of this program.

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lecp voyager

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  • Published: 04 November 2019

Energetic charged particle measurements from Voyager 2 at the heliopause and beyond

  • Stamatios M. Krimigis   ORCID: orcid.org/0000-0003-2781-2386 1 , 2 ,
  • Robert B. Decker 1 ,
  • Edmond C. Roelof 1 ,
  • Matthew E. Hill 1 ,
  • Carl O. Bostrom 1 ,
  • Konstantinos Dialynas 2 ,
  • George Gloeckler 3 ,
  • Douglas C. Hamilton 4 ,
  • Edward P. Keath 1 &
  • Louis J. Lanzerotti 5  

Nature Astronomy volume  3 ,  pages 997–1006 ( 2019 ) Cite this article

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  • Astronomy and astrophysics
  • Interstellar medium

The long-anticipated encounter by Voyager 2 (V2) of the region between the heliosphere and the very local interstellar medium (VLISM) occurred toward the end of 2018. Here, we report measurements of energetic (>28 keV) charged particles on V2 from the interface region between the heliosheath, dominated by heated solar wind plasma, and the VLISM, expected to contain cold non-solar plasma and the Galactic magnetic field. The number of particles of solar origin began a gradual decrease on 7 August 2018 (118.2 au), while those of Galactic origin (Galactic cosmic rays) increased ~20% in number over a period of a few weeks. An abrupt change occurred on 5 November when V2 was located at 119 au, with a decrease in the number of particles at energies of >28 keV and a corresponding increase in the number of Galactic cosmic rays of energy E  > 213 MeV. This signature of the transition to the VLISM resembles, but is very different from, that observed on Voyager 1 at ~121.6 au, associated with the putative crossing of the heliopause some six years earlier.

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Data availability

The V1 and V2 LECP measurements, including the in-situ LECP ion data used in this study, can be accessed through NASA’s public Planetary Data System ( https://pds.nasa.gov/ ), while the solar wind dynamic pressure measurements can be accessed through the OMNI web page ( ftp://spdf.gsfc.nasa.gov/pub/data/omni/low_res_omni/ ). Any other data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.

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Acknowledgements

We are grateful to L. Burlaga and J. Richardson on the Voyager team, who shared their data with us before publication. Work at the Johns Hopkins University Applied Physics Laboratory is supported by NASA contract NNN06AA01C and by subcontract at the University of Maryland and Fundamental Technologies. We thank S. Nylund, J. Gunther, J. Manweiler and S. Lasley for their assistance in the data processing efforts. This paper is dedicated to the members of the original LECP team who are no longer with us, T. Armstrong, I. Axford and C. Y. Fan. We are grateful to the original Voyager Program Scientist at NASA headquarters, M. Mitz, whose advocacy of state-of-the-art instrumentation for Voyager resulted in comprehensive measurements through all the years of this pioneering mission.

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Office of Space Research and Technology, Academy of Athens, Athens, Greece

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Contributions

All authors were actively involved in aspects of this manuscript. S.M.K. contributed most of the text, and R.B.D. and S.M.K. carried out most of the data analysis; R.B.D. and E.C.R. contributed to the text and provided theory and interpretations; K.D. provided the solar wind pressure analysis.

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Krimigis, S.M., Decker, R.B., Roelof, E.C. et al. Energetic charged particle measurements from Voyager 2 at the heliopause and beyond. Nat Astron 3 , 997–1006 (2019). https://doi.org/10.1038/s41550-019-0927-4

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Sensing the solar system’s edge.

Built to measure the various ions, electrons and cosmic rays originating from the solar system and the galaxy, the Low-Energy Charged Particle (LECP) instruments provided invaluable details as both Voyager spacecraft crossed into interstellar space.

About the Instrument

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Launched in 1977, the Voyager 1 and 2 spacecraft performed the first (and, so far, only) tour of the outer planets and their moons, together visiting the giants Jupiter, Saturn, Uranus and Neptune. Today, both Voyagers are venturing in unexplored regions far beyond these worlds: They’re outside the heliosphere, the region dominated by the solar wind, in interstellar space.

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APL’s Low Energy Charged Particle (LECP) instruments aboard each Voyager spacecraft were built to detect the various electrons and ions originating from the planets, the Sun’s solar wind and the galaxy. The LECP on Voyager 1 sensed the termination shock — the region where the Sun’s solar wind of charged particles slows to subsonic speeds because of interactions with the local interstellar medium — in December 2004, and the LECP on Voyager 2 sensed it in August 2007. LECP was one of two instruments that also detected the dramatic switch from energetic charged particles from the solar system to galactic cosmic ray particles from the Milky Way when Voyagers 1 and 2 left the Sun’s protective heliosphere through a boundary called the heliopause.

Since starting their journey in 1977, the Voyager 1 and Voyager 2 spacecraft have made history again and again, bringing us the first close-up images of the giant planets Jupiter, Saturn, Uranus, Neptune and several of their moons, as well as becoming the first spacecraft to ever enter interstellar space. Their current mission, the Voyager Interstellar Mission, will explore the outermost edge of the Sun's domain and beyond.

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The Low Energy Charged Particle (LECP) experiment on the Voyager spacecraft

  • Published: December 1977
  • Volume 21 , pages 329–354, ( 1977 )

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  • S. M. Krimigis 1 ,
  • T. P. Armstrong 2 ,
  • W. I. Axford 3 ,
  • C. O. Bostrom 4 ,
  • C. Y. Fan 5 ,
  • G. Gloeckler 6 &
  • L. J. Lanzerotti 7  

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The Low Energy Charged Particle (LECP) experiment on the Voyager spacecraft is designed to provide comprehensive measurements of energetic particles in the Jovian, Saturnian, Uranian and interplanetary environments. These measurements will be used in establishing the morphology of the magnetospheres of Saturn and Uranus, including bow shock, magnetosheath, magnetotail, trapped radiation, and satellite-energetic particle interactions. The experiment consists of two subsystems, the Low Energy Magnetospheric Particle Analyzer (LEMPA) whose design is optimized for magnetospheric measurements, and the Low Energy Particle Telescope (LEPT) whose design is optimized for measurements in the distant magnetosphere and the interplanetary medium. The LEMPA covers the energy range from ∼10 keV to > 11 MeV for electrons and from ∼15 keV to ≳ 150 MeV for protons and heavier ions. The dynamic range is ∼0.1 to ≳ 10 11 cm −2 sec −1 sr −1 overall, and extends to 10 13 cm −2 sec −1 sr −1 in a current mode operation for some of the sensors. The LEPT covers the range ∼0.05 ≤ E ≳ 40 MeV/nucleon with good energy and species resolution, including separation of isotopes over a smaller energy range. Multi-d E /d x measurements extend the energy and species coverage to 300–500 MeV/nucleon but with reduced energy and species resolution. The LEPT employs a set of solid state detectors ranging in thickness from 2 to ∼2450 μ, and an arrangement of eight rectangular solid state detectors in an anticoincidence cup. Both subsystems are mounted on a stepping platform which rotates through eight angular sectors with rates ranging from 1 revolution per 48 min to 1 revolution per 48 sec. A ‘dome’ arrangement mounted on LEMPA allows acquisition of angular distribution data in the third dimension at low energies. The data system contains sixty-two 24-bit sealers accepting data from 88 separate channels with near 100% duty cycle, a redundant 256-channel pulse height analyzer (PHA), a priority system for selecting unique LEPT events for PHA analysis, a command and control system, and a fully redundant interface with the spacecraft. Other unique features of the LECP include logarithmic amplifiers, particle identifiers, fast (∼15 ns FWHM) pulse circuitry for some subsystems, inflight electronic and source calibration and several possible data modes.

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Krimigis, S.M., Armstrong, T.P., Axford, W.I. et al. The Low Energy Charged Particle (LECP) experiment on the Voyager spacecraft. Space Sci Rev 21 , 329–354 (1977). https://doi.org/10.1007/BF00211545

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Title : Active carbons as nanoporous materials for solving of environmental problems

However, up to now, the main carriers of catalytic additives have been mineral sorbents: silica gels, alumogels. This is obviously due to the fact that they consist of pure homogeneous components SiO2 and Al2O3, respectively. It is generally known that impurities, especially the ash elements, are catalytic poisons that reduce the effectiveness of the catalyst. Therefore, carbon sorbents with 5-15% by weight of ash elements in their composition are not used in the above mentioned technologies. However, in such an important field as a gas-mask technique, carbon sorbents (active carbons) are carriers of catalytic additives, providing effective protection of a person against any types of potent poisonous substances (PPS). In ESPE “JSC "Neorganika" there has been developed the technology of unique ashless spherical carbon carrier-catalysts by the method of liquid forming of furfural copolymers with subsequent gas-vapor activation, brand PAC. Active carbons PAC have 100% qualitative characteristics of the three main properties of carbon sorbents: strength - 100%, the proportion of sorbing pores in the pore space – 100%, purity - 100% (ash content is close to zero). A particularly outstanding feature of active PAC carbons is their uniquely high mechanical compressive strength of 740 ± 40 MPa, which is 3-7 times larger than that of  such materials as granite, quartzite, electric coal, and is comparable to the value for cast iron - 400-1000 MPa. This allows the PAC to operate under severe conditions in moving and fluidized beds.  Obviously, it is time to actively develop catalysts based on PAC sorbents for oil refining, petrochemicals, gas processing and various technologies of organic synthesis.

Victor M. Mukhin was born in 1946 in the town of Orsk, Russia. In 1970 he graduated the Technological Institute in Leningrad. Victor M. Mukhin was directed to work to the scientific-industrial organization "Neorganika" (Elektrostal, Moscow region) where he is working during 47 years, at present as the head of the laboratory of carbon sorbents.     Victor M. Mukhin defended a Ph. D. thesis and a doctoral thesis at the Mendeleev University of Chemical Technology of Russia (in 1979 and 1997 accordingly). Professor of Mendeleev University of Chemical Technology of Russia. Scientific interests: production, investigation and application of active carbons, technological and ecological carbon-adsorptive processes, environmental protection, production of ecologically clean food.   

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First refuelling for Russia’s Akademik Lomonosov floating NPP

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The FNPP includes two KLT-40S reactor units. In such reactors, nuclear fuel is not replaced in the same way as in standard NPPs – partial replacement of fuel once every 12-18 months. Instead, once every few years the entire reactor core is replaced with and a full load of fresh fuel.

The KLT-40S reactor cores have a number of advantages compared with standard NPPs. For the first time, a cassette core was used, which made it possible to increase the fuel cycle to 3-3.5 years before refuelling, and also reduce by one and a half times the fuel component in the cost of the electricity produced. The operating experience of the FNPP provided the basis for the design of the new series of nuclear icebreaker reactors (series 22220). Currently, three such icebreakers have been launched.

The Akademik Lomonosov was connected to the power grid in December 2019, and put into commercial operation in May 2020.

Electricity generation from the FNPP at the end of 2023 amounted to 194 GWh. The population of Pevek is just over 4,000 people. However, the plant can potentially provide electricity to a city with a population of up to 100,000. The FNPP solved two problems. Firstly, it replaced the retiring capacities of the Bilibino Nuclear Power Plant, which has been operating since 1974, as well as the Chaunskaya Thermal Power Plant, which is more than 70 years old. It also supplies power to the main mining enterprises located in western Chukotka. In September, a 490 km 110 kilovolt power transmission line was put into operation connecting Pevek and Bilibino.

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Newsweek

Strange Glow Over Moscow Skies Triggers Panic as Explosions Reported

B right flashes lit up the night sky in southern Moscow in the early hours of Thursday morning, new footage appears to show, following reports of an explosion at an electrical substation on the outskirts of the city.

Video snippets circulating on Russian-language Telegram channels show a series of flashes on the horizon of a cloudy night sky, momentarily turning the sky a number of different colors. In a clip shared by Russian outlet MSK1.ru, smoke can be seen rising from a building during the flashes lighting up the scene.

Newsweek was unable to independently verify the details of the video clips, including when and where it was filmed. The Russian Ministry of Emergency situations has been contacted via email.

Several Russian Telegram accounts said early on Thursday that residents of southern Moscow reported an explosion and a fire breaking out at an electrical substation in the Leninsky district, southeast of central Moscow.

Local authorities in the Leninsky district told Russian outlet RBC that the explosion had happened in the village of Molokovo. "All vital facilities are operating as normal," Leninsky district officials told the outlet.

The incident at the substation in Molokovo took place just before 2 a.m. local time, MSK1.ru reported.

Messages published by the ASTRA Telegram account, run by independent Russian journalists, appear to show residents close to the substation panicking as they question the bright flashes in the sky. One local resident describes seeing the bright light before losing access to electricity, with another calling the incident a "nightmare."

More than 10 villages and towns in the southeast of Moscow lost access to electricity, the ASTRA Telegram account also reported. The town of Lytkarino to the southeast of Moscow, lost electricity, wrote the eastern European-based independent outlet, Meduza.

Outages were reported in the southern Domodedovo area of the city, according to another Russian outlet, as well as power failures in western Moscow. Electricity was then restored to the areas, the Strana.ua outlet reported.

The cause of the reported explosion is not known. A Telegram account aggregating news for the Lytkarino area described the incident as "an ordinary accident at a substation."

The MSK1.ru outlet quoted a local resident who speculated that a drone may have been responsible for the explosion, but no other Russian source reported this as a possible cause.

Ukraine has repeatedly targeted Moscow with long-range aerial drones in recent months, including a dramatic wave of strikes in late May.

On Sunday, Moscow Mayor Sergei Sobyanin said the region's air defense systems had intercepted an aerial drone over the city of Elektrostal, to the east of Moscow. No damage or casualties were reported, he said.

The previous day, Russian air defenses detected and shot down another drone flying over the Bogorodsky district, northeast of central Moscow, Sobyanin said.

There is currently no evidence that an aerial drone was responsible for the reported overnight explosion at the electrical substation in southern Moscow.

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Stills from footage circulating on Telegram early on Thursday morning. Bright flashes lit up the night sky in southern Moscow, new footage appears to show, following reports of an explosion at an electrical substation on the outskirts of the city.

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Publication bibliography.

1990's LECP Publication Bibliography

LECP - Low Energy Charged Particles Investigation

2000's | 1990's | 1980's | 1970's

Burger, A., S.V. Chalov, R.B. Decker, J. Dwyer, P.R. Gazis, D. Intriligator, J.R. Jokipii, L.J. Lanzerotti, A.J. Lazarus, G. Mason, F.B. McDonald, V.J. Pizzo, M.S. Potgeiter, and I. Richardson, "Corotating Interaction Regions, eds. A. Balogh, J. Gosling, J.R. Jokipii, R. Kallenbach, and J. Kunow, Kluwer Academic Publishers (Dordrecht), in press, 1999.

Decker, R.B., A.G. Ananth, S.M. Krimigis, D.C. Hamilton, and M.E. Hill, "Small-Scale Variations in ACR Intensities at Voyagers 1 and 2 in 1992-1998," Proc. 26 th Intl. Cosmic Ray Conf., submitted, 1999.

Decker, R.B., E.C. Roelof, and S.M. Krimigis, "Solar Energetic Particles from the April 1998 Activity: Observations from 1 to 72 AU," Proc. 26 th Intl. Cosmic Ray Conf., submitted, 1999.

Hamilton, D.C., M.E. Hill, G. Gloeckler, R.B. Decker, and S.M. Krimigis, "Anomalous Cosmic Ray Spectra in the Outer Heliosphere: 1992-1998," Proc. 26 th Intl. Cosmic Ray Conf., submitted, 1999.

Lazarus, A.J., J.D. Richardson, R.B. Decker, F.B. McDonald, "CIRs Observed from Voyager 2 in the Outer Heliosphere," Proc. Of Solar Wind 9, in press, 1999.

Lazarus, A.J., J.D. Richardson, R.B. Decker, F.B. McDonald, "Voyager 2 Observations of Corotating Interaction Regions (CIRs) in the Outer Helio-sphere," in Corotating Interaction Regions, eds. A. Balogh, J. Gosling, J.R. Jokipii, R. Kallenbach, and H. Kunow , Kluwer Academic Publishers (Dordrecht), in press, 1999.

Mason, G.M., R. Von Steiger, R.B. Decker, M.I. Desai, J.R. Dwyer, L. A. Fisk, M. Franz, G. Gloeckler, J.T. Gosling, M. Hilchenbach, R. Kallenbach, E. Keppler, B. Klecker, G. Mann, J.E. Mazur, I.G. Richardson, R. Sanderson, G.M.Simnett, Y.M. Wang, and R.F. Wimmer-Schweingruber, "Origin, Injection, and Observations of CIR Particles: Observations, in Corotating Interaction Regions," eds. A. Balogh, J. Gosling, J.R. Jokipii, R. Kallenbach, and H. Kunow, Kluwer Academic Publishers (Dordrecht), in press, 1999.

McKibben, R.B., C. Lopate, M. Zhang, J.A. Simpson, R.B. Decker, and S.M. Krimigis, "The Onset of Modulation in Cycle 23 from 1 to 72 AU," Proc. 26 th Intl. Cosmic Ray Conf., submitted, 1999.

McNutt, R.L., Jr., J. Lyon, C.G. Goodrich, and M. Wiltberger , "3D MHD Simulations of the Heliosphere-VLSIM Interaction," Proc. Of Solar Wind 9, in press, 1999.

McNutt, R.L., Jr., J. Lyon, and C.G. Goodrich , "Simulation of the Heliosphere: Generalized Charge-exchange Cross Sections," J.Geophys. Res., in press, 1999.

Mosley, C. and T.P. Armstrong, "Studies of Low Energy medium Nuclei in the Outer Heliosphere with Voyagers 1 and 2," J. Geophys. Res., submitted, 1999.

Nikitin, A.V., R.L. Davidchack, and T.P. Armstrong, "The Effect of Pulse Pile-up on Threshold Crossing Rates in a System with a Known Impulse Response," Nucl. Instr. Methods in Phys. Res., in press, 1999.

Hill, M.E., "Methods of Analysis for Voyager LECP Data," Scholarly paper required by the Dept. of Physics, Univ. of Maryland, for the M.S. degree and for admission to candidacy for the Ph.D. degree, 149 pages, June 1998.

Kane, M., R.B. Decker, B.H. Mauk, and S.M. Krimigis, "The Solar Wind Velocity Determined from Voyager 1 and 2: Low Energy Charged Particle Measurements in the Outer Heliosphere," J. Geophys. Res., Vol. 108, p. 267, 1998.

Mauk, B.H., R.W. McEntire, D.J. Williams, A. Lagg, E.C. Roelof, S.M. Krimigis, T.P. Armstrong, T.A. Fritz, L.J. Lanzerotti, J. G. Roederer, and B. Wilken, "Galileo-Measured Depletion of Near-Io Hot Ring Current Plasmas Since the Voyager Epoch," J. Geophys. Res., Vol. 103, p. 4,715, 1998.

McNutt, R.L., J. Lyon, C.C. Goodrich, "Simulations of the Heliosphere 1. Charge Exchange and Elastic-Collision Operators," J. Geophys. Res., Vol. 103, p. 1,905, 1998.

Simnett, G.M., H. Kunow, E. Fluekiger, T. Horbury, J. Kota, A.J. Lazarus, E.C. Roelof, R.B. Decker, J.A. Simpson, and M. Zhang, "Corotating Particle Events," Sp. Sci. Rev., p. 83, 1998.

Simnett, G.M., H. Kunow, E. Fluekiger, T. Horbury, J. Kota, A.J. Lazarus, E.C. Roelof, R.B. Decker, J.A. Simpson, and M. Zhang, "Corotating Particle Events, in Cosmic Ray Modulation in the Three-Dimensional Heliosphere," eds. L.A. Fisk, J.R. Jokipii, G.M. Simnett, R. von Steiger, and K.P. Wenzel, Kluwer Academic Publishers (Dordrecht), p. 259, 1998.

Boufaida, M., and T.P. Armstrong, "Spatial Variations of 0.2 to 5 MeV Protons I the 1-5 AU in-Ecliptic Region from Ulysses, Voyager 1 and 2, and IMP 8 Gradient Studies", J. Geophys. Res., Vol. 102, p. 7013, 1997.

Giacalone, J., J.R. Jokipii, R.B. Decker, S.M. Krimigis, M. Scholer, and H. Kucharek, "Pre-acceleration of Anomalous Cosmic Rays in the Inner Heliospere," Astrophys. J., Vol. 486, p. 471, 1997.

Hamilton, D.C., M.E. Hill, R.B. Decker, and S.M. Krimigis, "Temporal and Spatial Variations in the Spectra of Low Energy Ions in the Outer Heliosphere," Proc. 25 th Intl. Cosmic Ray Conf ., Vol. 2, p. 261, 1997.

Krimigis, S.M., R.B. Decker, D.C. Hamilton, and M.E. Hill, "Energetic Ions in the Outer Heliosphere, 1992-1997," Proc. 25 th Intl. Cosmic Ray Conf ., Vol. 1, p. 393, 1997

Lanzerotti, L.J., C.G. Maclennan, T.P. Armstrong, E.C. Roelof, R.E. Gold, and R.B. Decker, "Low Energy Charged Particles in the High Latitude Heliosphere," Adv. Space Res ., Vol. 19, p. 851, 1997.

Paranicus, C., A.F. Cheng, B.H. Mauk, E.P. Keath, and S.M. Krimigis, "Evidence of a Source of Energetic Ions at Saturn," J. Geophys. Res., Vol. 102, p. 14,459, 1997.

Roelof, E.C., G.M. Stinnett, R.B. Decker, L.J. Lanzerotti, C.G. Maclennan, T.P. Armstrong, R.E. Gold, and S.M. Krimigis, "Reappearance of Recurrent Low Energy particle Events at Ulysses/HI-SCALE in the Northern Heliosphere," J. Geophys. Res., Vol. 102, p. 11,251, 1997.

Simnett, S.M., R.B. Decker, and E.C. Roelof, "Confinement of Electrons Accelerated at Distant, High Latitude Corotating Interaction Regions in the Inner Heliosphere," Proc. 25 th Intl. Cosmic Ray Conf., Vol. 1, p. 361, 1997.

Boufaida, M., T.P. Armstrong, J. Giacalone, E.C. Roelof, G.M. Simnett, and K.A. Sayle, "Evidence for Shock Acceleration to 2-4 MeV Nucleon of Interstellar Helium in the 1-5 AU region from Ulysses, Voyagers 1 and 2, and IMP 8 Gradient Studies," J. Geophys. Res., 1996.

Decker, R.B., S.M. Krimigis, L.F. Burlaga, and R.L. McNutt, Jr., "An Unusual Shock Event Observed at 35 AU by Voyager 2 in May 1991," Geophys. Res. Lett., 1996.

Decker, R.B., S.M. Krimigis, L.F. Burlaga, and R.L. McNutt, Jr., "Pressure and Energy Carried by the 30 keV Superthermal Ion Population during September 1991 GMIR at Voyagers 1 and 2," J. Geophys. Res., 1996.

Decker, R.B., S.M. Krimigis, and M. Kane, "Spatial Gradients, Energy Spectra, and Anisotropies of Ions 30 keV at CIR Shocks Observed at Voyagers 1 and 2 between 1 to 50 AU," J. Geophys. Res., 1996.

Giacalone, J., J.R. Jokipii, R.B. Decker, S.M. Krimigis, M. Scholer, and J. Kucharek, "Pre-acceleration of Anomlaous Cosmic Rays in the Inner Helisophere," Astrophys. J., submitted, 1996.

Kane, M., R.B. Decker, B.H. Mauk, R.L. McNutt, Jr., and S.M. Krimigis, "The Solar Wind Velocity Determined from Voyager 1 and 2 Low Energy Charged Particle Measurements in the Outer Heliosphere," J. Geophys. Res., 1996.

Krimigis, S.M., "The New Solar System: Solar Activity and the Solar Wind Interaction with the Planets, " Proc. Israel Institute of Advanced Studies at Tel Aviv University, Raymond and Beverly Sackler Distinguished Lectures, Geophysics and Planetary Sciences, p. 28, May 26 - June 7, 1996.

C.G. Maclennan, L.J. Lanzerotti, R.B. Decker, S.M. Krimigis, D.G. Hamilton, and M. Collier, "Helioradius Dependence of Interplanetary Carbon and Oxygen Abundances During 1991 Solar Activity," Astrophys. J. Lett., 468, L123, 1996.

Mauk, B.H., S.A. Gary, M. Kane, E.P. Keath, S.M. Krimigis and T. P. Armstrong, "Hot Plasma Parameters of Jupiter's Inner Magnetosphere," J. Geophys. Res. Vol. 101, p. 7685, 1996.

Paranicus, C.A., A.F. Cheng, and B.H. Mauk, "Charged Particle Phase Space Densities in the Magnetospheres of Uranus and Neptune, J. Geophys. Res., Vol. 101 , 10681, 1996.

Paranicus, C.A. and A.F. Cheng, " Satellite Micro-Signatures at Saturn," Icarus, Vol. 125, p. 380, 1996.

Paranicus, C.A., A.F. Cheng, B.H. Mauk, E.P. Keath, and S.M. Krimigis, "Evidence of a Source of Energetic Ions at Saturn," J. Geophys. Res., submitted , 1996.

Roelof, E.C., G.M. Sinnett, R.B. Decker, L.J. Lanzerotti, C.G. Maclennan, T.P. Armstrong, R.E. Gold, and S.M. Krimigis , "Reappearance of Recurrent Low Energy Particle Events at Ulysses/HI-SCALE in the Northern Hemisphere, J. Geophys. Res., submitted, 1996.

Collier, M.R., "The Adiabatic Transport of Superthermal Distributions Modeled by Kappa Functions," Geophys. Res. Lett., Vol. 2673, 1995.

Collier, M.R. and D.C. Hamilton, "The Relationship between Kappa and Temperature in Energetic Ion Spectra at Jupiter," Geophys. Res. Lett., in press, 1995.

Collier, M.R., "Jovian Magnetospause Breathing ., Planet. Space Sci., p. 43, 1995.

Decker, R.B., S.M. Krimigis, L.F. Burlaga, and R.L. McNutt, "Pressure and Energy Carried by Superthermal Ions during the September 1991 GMIR at Voyagers 1 and 2," 24th Intl. Cosmic Ray Conf., Vol. 4, p. 425, 1995.

Decker, R.B., S.M. Krimigis, and M. Kane, "Spatial Gradients, Energy Spectra, and Anisotropies of Ions 30 keV at CIR Shocks from 1 to 50 AU," 24th Intl. Cosmic Ray Conf., Vol. 4, p. 421, 1995.

Decker, R.B., S.M. Krimigis, R.L. McNutt, D.C. Hamilton, and M.R. Collier, "Latitude-associated Differences in Low Energy Charged Particle Activity at Voyagers 1 and 2 During 1991 to Early 1994," Space Sci. Rev., Vol. 72, p. 347, 1995.

Kane, M., R.B. Decker, B.H. Mauk, and S.M. Krimigis, "Latitudinal and Radial Variation of Shock Associated 30 keV Ion Spectra and Anisotropies at Voyagers 1 and 2," Space Sci. Rev., Vol. 72, p. 353, 1995.

Kane, M., B.H. Mauk, E.P. Keath, and S.M. Krimigis, "Hot Ions in Jupiter's Magnetodisc: A Model for Voyager 2 Low Energy Charged Particle Measurements," J. Geophys. Res., Vol. 100, 19473, 1995.

Krimigis, S.M., R.B. Decker, R.L. McNutt, D. Venkatesan, D.H. Hamilton, and M. Collier, "Energetic Particle Activity in the Heliosphere, 1991-1995," 24th Intl. Cosmic Ray Conf., Vol. 4, p. 401, 1995.

Krupp, N., R.B. Decker, L.J. Lanzerotti, E. Keppler, S.M. Krimigis, R.E. Gold, "Comparison of Recurrent Ion Events Using Ulysses HI-SCALE and EPAC Data and Voyager LECP Data," 24th Intl. Cosmic Ray Conf., Vol. 4, p. 431, 1995.

Mauk, B.H., S.M. Krimigis, A.F. Cheng, and R.S. Selesnick, "Energetic Particles and Hot Plasmas of Neptune," Neptune and Triton, edited by D. Cruikshank and M. Mathews, The University of Arizona Press, Tucson, AZ, pp. 169-232, 1995.

Paranicus, C. and A.F. Cheng, "Investigation of Additional Particulate Risk to Cassini spacecraft Based on Voyager Saturn Data," Report to JPL MIMI Science Team, September, 1995.

Thomson, D.J., C.G. Maclennan, and L.J. Lazerotti, "Propagation of Solar Oscillations through the Interplanetary Medium," Nature, Vol. 376, pp. 139-144, 1995.

Decker, R.B. and A.F. Cheng, A model of Triton's role in Neptune's magnetosphere, J. Geophys. Res., Vol. 99, 19027, 1994.

Kane, M., B. H. Mauk, E.P. Keath, and S.M. Krimigis, Jovian magnetospheric convection models: Constraints imposed by Voyager 2 low energy charged particle measurements, J. Geophys. Res., submitted, 1994 .

Mauk, B.H., S.M. Krimigis, and M.H. Acuña, Neptune's inner magnetosphere and aurora: Energetic particle constraints, J. Geophys. Res., Vol. 99, 14781, 1994.

Mauk, B.H., E.P. Keath, and S.M. Krimigis, Unusual satellite-electron signature within the Uranian magnetosphere and its implications regarding whistler electron loss processes, J. Geophys. Res., Vol. 99, 19441, 1994.

Paranicas, C. and A.F. Cheng, Drift shells and aurora computed using the 08 magnetic field model for Neptune, J. Geophys. Res., Vol. 99, 19433, 1994.

Villanueva, L., R.L. McNutt, Jr., A.J. Lazarus, and J.T. Steinberg, Voyager observations of O +6 and other minor ions in the solar wind, J. Geophys. Res., Vol. 99, 2553-2565, 1994.

Collier, M.R., "Energetic Particle Acceleration in the Jovian Magnetosphere," Ph.D. Dissertation, Dept. of Physics, U. of Maryland, August, 1993.

Collier, M.R., "On Generating Kappa-like Distribution Functions Using Velocity Space Levy Flights," Geophys. Res. Lett., Vol. 20, pp.1521-1534, 1993.

Decker, R.B., "The Role of Magnetic Loops in Particle Acceleration at Nearly Perpendicular Shocks," J. Geophys. Res., Vol. 98, p. 33, 1993.

Decker, R.B. and S.M. Krimigis, "Two unusual shock events observed at the Voyagers in 1991," 23rd Intl. Cosmic Ray Conf., SH 4.1.11, July 1993, Calgary, Canada, Vol. 3, Contributed Papers, p. 310-313, 1993.

Decker, R. B., S. M. Krimigis, and D. Venkatesan, "A survey of Energetic Particle Activity in the Heliosphere in 1991-92," 23rd Intl. Cosmic Ray Conf., SH 6.3.7, July 1993, Calgary, Canada, Vol. 3, Contributed Papers, p. 481-484, 1993.

Desai, M.I., G.M. Simnett, S.J. Tappin, L.J. Lanzerotti, S.M. Krimigis, T.P. Armstrong, and E.T. Sarris, "Title????," 23rd Intl. Cosmic Ray Conf., SH 4.2.6, July 1993, Calgary, Canada, Vol. 3, Contributed Papers, 432-345, 1993.

Kane, M., R.B. Decker, B.H. Mauk, and S.M. Krimigis, "Shock Conditions and Hot Ion Anisotropies During the Voyager 2 Encounter with a 1989 Interplanetary Shock at 29 Au," 23rd Intl. Cosmic Ray Conf., SH 4.1.9, July 1993, Calgary, Canada, Vol. 3, Contributed Papers, 302-305, 1993.

Lanzerotti, L.J., T. P. Armstrong, C.G. Maclennan, G. M. Simnett, A. F. Cheng, R. E. Gold D. J. Thomson, S.M. Krimigis, K.A. Anderson, S.E. Hawkins, III, M. Pick, E.C. Roelof, E.T. Sarris, and S.J. Tappin, "Measurements of Hot Plasmas in the Magnetosphere of Jupiter," Planet. Space Sci., December, 1993.

Mauk, B.H., S.M. Krimigis, A.F. Cheng, R.S. Selesnick, "Energetic Particles and Hot Plasmas of Neptune," in Neptune and Triton , D.P. Cruickshank, ed., Univ. of Arizona Press, in press, 1993.

Paranicas, C. and A.F. Cheng, "Absence of Magnetic Trapping on Closed Field Lines at Neptune," Geophys. Res. Lett., Vol. 20, pp. 2805-2808, 1993.

Ye, G. and T.P. Armstrong, "Electron Distributions in the Inner Jovian Magnetosphere: Voyager 1 Observations," J. Geophys. Res., Vol. 98, pp. 21253-21264, 1993.

Decker, R.B., "The Role of Magnetic Loops in Particle Acceleration at Nearly Perpendicular Shocks," J. Geophys. Res., in press, 1992.

Kane, M., B.H. Mauk, E.P. Keath, S.M. Krimigis, "A Convected Distribution Model for Hot Ions in the Jovian Magnetodisc," Geophys. Res. Lett., Vol. 19, pp. 1435-1438, 1992.

Krimigis, S.M., "Voyager Energetic Particle Observations at Interplanetary Shocks and upstream of Planetary Bow Shocks," Space Sci. Rev., Vol. 59, pp. 167-201, 1992.

Krimigis, S.M., "Particles and Field Measurements at Neptune with Voyager 2," Adv. Space Res., Vol. 12, pp. 55-70, 1992.

Krimigis, S.M., "The Magnetosphere of Neptune," The Planetary Report, Vol. XII, pp. 10-13, 1992.

Lepping, R.P., L.F. Bulaga, A.J. Lazarus, V.M. Vasyliunas, A. Szabo, J. Steinberg, N.F.Ness, S.M. Krimigis, "Neptune's Polar Cusp Region: Observations and Magnetic Field Analysis," J. Geophys. Res., Vol. 97, pp. 8135-8144, 1992.

Cheng, A.F., S.M. Krimigis, and L.J. Lanzerotti, "Energetic Particles at Uranus," Uranus , J.T. Bergstralh, E.D. Miner, and M.S. Matthews (Eds), U. of Arizona Press, p. 253, 1991.

Mauk, B.H., E.P. Keath, M. Kane, S.M. Krimigis, A.F. Cheng, M.H. Acuña, T. P. Armstrong, and N.F. Ness, "The Magnetosphere of Neptune: Hot Plasmas and Energetic Particles", J. Geophys. Res ., Vol. 96, p. 19061, 1991.

Paranicas, C.P., and A.F. Cheng, "Satellite Sweeping of Energetic Particles at Neptune," J. Geophys. Res ., Vol. 96, p. 19131, 1991.

Paranicas, C.P., and A.F. Cheng, "Theory of Ring Sweeping of Energetic Particles," J. Geophys. Res ., Vol. 96, p. 19123, 1991.

Cheng, A.F., "Triton Torus and Neptune Aurora," Geophys. Res. Lett ., Neptune Special Issue, 1990.

Cheng, A.F., "Global Magnetic Anomaly and Aurora of Neptune." Geophys. Res. Lett ., Neptune Special Issue, 1990.

Cheng, A.F., S.M. Krimigis, and L.J. Lanzerotti, "Energetic Particles at Uranus," Uranus , U. of Arizona Press, 1990.

Decker, R.B., S.M. Krimigis, and D. Venkatesan, "Onset of Cosmic Ray Modulation Observed at Voyagers 1 and 2 During the Early Phase of Solar Cycle 22," 21st Intl. Cosmic Ray Conf ., Adelaide, Australia, p. 152, 1990.

Krimigis, S.M., "The Encounter of Voyager 2 with Neptune's Magnetosphere," Magnetospheric Physics: Achievements and Prospects, B. Hultqvist and C.G. Falthammer (Eds.), Plenum Press, 1990.

Krimigis, S.M., "The Magnetosphere of Neptune as Revealed by Voyager," COSPAR Proceedings , Adv. Space Res. , 1991.

Krimigis, S.M., B.H. Mauk, A.F. Cheng, E.P. Keath, M. Kane, T.P. Armstrong, G. Gloeckler, and L.J. Lanzerotti, "Hot Plasma Parameters in Neptune's Magnetosphere," Geophys. Res. Lett ., 1990.

Mauk, B.H., E.P. Keath, and S.M. Krimigis, "The Voyager Program at APL," APL Tech. Dig ., Vol. 11, p. 63, 1990.

Strobel, D.F., A.F. Cheng, M. Summers, and D. Strickland, "Magnetosphere Interaction with Triton's Ionosphere," Geophys. Res. Lett ., 1990.

Venkatesan, D., R.B. Decker, S.M. Krimigis, T. Mathews, and E.T. Sarris, "The Great Forbush Decrease of March 1989 and the Interplanetary Energetic Particle Environment," 21st Intl. Cosmic Ray Conf. , Adelaide, Australia, p. 247, 1990.

Venkatesan, D., and S.M. Krimigis, "Into the Night Between the Stars," Astronomy , Vol. 18, p. 42, 1990.

Cheng, A.F., and S.M. Krimigis, "A Model of Global Convection in Jupiter's Magnetosphere," J. Geophys. Res ., Vol. 94, p. 12003, 1989.

Cheng, A.F., and S.M. Krimigis, "Energetic Neutral Particle Imaging of Saturn's Magnetosphere," Solar System Plasma Physics, J.H. Waite, Jr., J. Burch, and R. Moore (Eds.), AGU Monograph, No. 54, p. 253, 1989.

Krimigis, S.M., T.P. Armstrong, W.I. Axford, C.O. Bostrom, A.F. Cheng, G. Gloeckler, D.C. Hamilton, E.P. Keath, et al., "Hot Plasma and Energetic Particles in Neptune's Magnetosphere," Science, Vol. 246, p. 1483, 1989.

Kurth, W.S., D.A. Gurnett, F.L. Scarf, and B.H. Mauk, "Plasma Waves in the Magnetotail of Uranus," J. Geophys. Res ., Vol. 94, p. 3505, 1989.

Thompson, W.R., S.K. Singh, B.N. Khare, and C. Sagan, "Triton: Stratospheric Molecules and Organic Sediments," Geophys. Res. Lett ., Vol. 16, p. 981, 1989.

Thompson, W.R., T. Henry, J. Schwartz, B.N. Khare, and C. Sagan, "Production and Fate of Hydrocarbons, Nitriles, and Heteropolymers on Titan," Origins Life , Vol. 19, p. 475, 1989.

Decker, R.B., "Computer Modeling of Test Particle Acceleration at Oblique Shocks," Space Sci. Rev ., Vol. 48, p. 195, 1988.

Gold, R.E., R.B. Decker, S.M. Krimigis, L.J. Lanzerotti, and C.G. Maclennan, "The Latitude and Radial Dependence of Shock Acceleration in the Heliosphere," J. Geophys. Res ., Vol. 93, p. 991, 1988.

Krimigis, S.M. and D. Venkatesan, "In Situ Acceleration of Charged Particles in the Outer Solar System Observed by the Voyager Spacecraft," Astrophys. & Space Sci., Vol. 144, p. 463, 1988.

Krimigis, S.M., E.P. Keath, B.H. Mauk, A.F. Cheng, L.J. Lanzerotti, R.P. Lepping, and N.F. Ness "Observations of Energetic Ion and Electron Enhancements Upstream and Downstream of Uranus' Bow Shock by the Voyager 2 Spacecraft," Planet. Space Sci ., Vol. 36, p. 311, 1988.

Smith, R.A., F. Bagenal, A.F. Cheng, and D.F. Strobel, "On the Energy Crisis in the Io Plasma Torus," Geophys. Res. Lett ., Vol. 15, p. 545, 1988.

Beeck, J., G.M. Mason, D.C. Hamilton, G. Wibberenz, H. Kunow, D. Hovestadt, and B. Klecker, "A Multi-Spacecraft Study of the Injection and Transport of Solar Energetic Particles," Astrophys. J ., Vol. 322, p. 1052, 1987.

Behannon, K.W., R.P. Lepping, E.C. Sittler, Jr., N.F. Ness, B.H. Mauk, S.M. Krimigis, and R.L. McNutt, Jr., "The Magnetotail of Uranus," J. Geophys. Res ., Vol. 92, p. 15354, 1987.

Bell, II, E.V., "Interactions of Charged Particles with Natural Satellites of Jupiter and Saturn," Ph. D. Dissertation , Dept. of Physics, U. of Kansas, 1987.

Cheng, A.F., "Proton and Oxygen Plasmas at Uranus," J. Geophys. Res ., Vol. 92, p. 15309, 1987.

Cheng, A.F., S.M. Krimigis, G.H. Mauk, E.P. Keath, C.G. Maclennan, L.J. Lanzerotti, M.T. Paonessa, and T. P. Armstrong, "Energetic Ion and Electron Phase Space Densities in the Magnetosphere of Uranus," J. Geophys. Res ., Vol. 92, p. 15315, 1987.

Coroniti, F.V., W.S. Kurth, F.L. Scarf, S.M. Krimigis, C.F. Kennel, and D.A. Gurnett, "Whistler Mode Emissions in the Uranian Radiation Belts," J. Geophys. Res ., Vol. 92, p. 15234, 1987.

Decker, R.B., S.M. Krimigis, and D. Venkatesan, "Latitudinal Gradient of Energetic Particles in the Outer Heliosphere during 1985-86," J. Geophys. Res ., Vol. 92, p. 3375, 1987.

Gold, R.E., L.J. Lanzerotti, and C.G. Maclennan, "Enhanced Low Energy (1MeV) Ion Fluxes in the Outer Heliosphere," Planet. Space Sci ., Vol. 35, p. 1359, 1987.

Krimigis, S.M., "Observations of Energetic Ions and Electrons at Interplanetary Shocks and Upstream of Planetary Bow Shocks by the Voyager Spacecraft," Proceedings of the International Symposium on Collisionless Shocks , Belatonfured, Hungary, K. Szego (Ed.), Central Institute for Research, Academy of Science, Budapest, p. 3, 1987.

Lanzerotti, L.J., W.L. Brown, and K.J. Marcantonio, "Experimental Study of Erosion of Methane Ice by Energetic Ions and Some Considerations for Astrophysics," Ap. J ., Vol. 313, p. 910, 1987.

Lanzerotti, L.J., C.G. Maclennan, J.N. Broughton, D. Venkatesan, and R.P. Lepping, "Magnetic Field and Particle Pressure in the Plasma Sheet of Jupiter," Magnetotail Physics, A.T.Y. Lui (Ed.), Johns Hopkins U. Press, p. 383, 1987.

Lanzerotti, L.J., W.L. Brown, C.G. Maclennan, A.F. Cheng, S.M. Krimigis, and R.E. Johnson "Effects of Charged Particles on the Surface of the Satellites and Rings of Uranus," J. Geophys. Res ., Vol. 92, p. 14949, 1987.

Mauk, B.H., S.M. Krimigis, E.P. Keath, A.F. Cheng, T.P. Armstrong, L.J. Lanzerotti, G. Gloeckler, and D.C. Hamilton, "The Hot Plasma and Radiation Environment of the Uranian Magnetosphere," J. Geophys. Res ., Vol. 92, p. 15283, 1987.

Mauk, B.H., and S.M. Krimigis, "Radial Force Balance Within Jupiter's Dayside Magnetosphere," J. Geophys. Res ., Vol. 92, p. 9931, 1987.

Paonessa, M., and A.F. Cheng, "Satellite Sweeping in Offset Tilted Dipole Fields," J. Geophys. Res ., Vol. 92, p. 1160, 1987.

Sittler, E.C., R.P. Lepping, B.H. Mauk, and S.M. Krimigis, "Detection of Hot Plasma Component Within the Core Regions of Jupiter's Distant Magnetotail," J. Geophys. Res ., Vol. 92, p. 9943, 1987.

Thompson, W.R., T. Henry, B.N. Khare, L. Flynn, J. Schwartz, and C. Sagan, "Uranian Auroral Chemistry," J. Geophys. Res ., Vol. 92, p. 15083, 1987.

Venkatesan, D., R.B. Decker, and S.M. Krimigis, "Cosmic Ray Intensity Gradients During 1984-86," 20th Intl. Cosmic Ray Conf. , Moscow, Vol. 2, p. 385, 1987.

Bell, II, E.V., and T.P. Armstrong, "Monte Carlo Simulation of Charged Particle Impact on the Satellites of Jupiter and Saturn," J. Geophys. Res ., Vol. 91, p. 1397, 1986.

Cheng, A.F., "Energetic Neutral Particles from Jupiter and Saturn," J. Geophys. Res ., Vol. 89, p. 4524, 1986.

Cheng, A.F., "Radial Diffusion and Ion Partitioning in the Io Torus," Geophys. Res. Lett ., Vol. 13, p. 517, 1986.

Cheng, A.F., "Magnetospheres of the Outer Planets," APL Tech. Digest, Vol. 7, p. 348, 1986.

Cheng, A.F., P. Haff, R.E. Johnson, and L.J. Lanzerotti, "Interactions of Planetary Magnetospheres with Icy Satellite Surfaces," Satellites, J.A. Burns and M.S. Matthews (Eds.), U. of Arizona Press, p. 403, 1986.

Gold, R.E., and D. Venkatesan, "Study of Interplanetary Spatial Structures During STIP Interval V (June-July, 1978)," Solar Technology Information Program (STIP) Symposium on Retrospective Analysis and Future Coordinated Intervals , 1986.

Gold, R.E., L.J. Lanzerotti, C. Maclennan, and S.M. Krimigis, "Latitude Dependence of Corotating Shock Acceleration in the Outer Heliosphere," The Sun and the Heliosphere in Three Dimensions, R.G. Marsden (Ed.), Reidel Publishers, Holland, p. 325, 1986.

Khurana, K.K., M.G. Kivelson, T.P. Armstrong, and R.J. Walker, "Voids in Jovian Magnetosphere Revisited: Evidence of Spacecraft Charging," Geophys. Res. Lett ., Vol. 92, p. 13399, 1986.

Krimigis, S.M., "Energetic Ions Upstream of Planetary Bow Shocks: Fermi Acceleration or Leakage?," Proceedings of the Comp. Study of Magnetospheric Systems-CNES , Cepadues Editions, France, p. 99, 1986.

Krimigis, S.M., "Luncheon at the White House: On Comets and the Planet Uranus," APL Tech. Digest, Vol. 7, p. 383, 1986.

Krimigis, S.M., "Hot Plasma and Unusual Composition in Jupiter's Magnetosphere, The Twenty-Two Most Frequently Cited Publications," APL Tech. Digest, Vol. 7, p. 403, 1986.

Krimigis, S.M., T.P. Armstrong, W.I. Axford, A.F. Cheng, G. Gloeckler, D.C. Hamilton, E.P. Keath, L.J. Lanzerotti, and B.H. Mauk, "The Magnetosphere of Uranus: Hot Plasma and Radiation Environment," Science, Vol. 233, p. 99, 1986.

Lanzerotti, L.J., W.L. Brown, and R.E. Johnson, "Astrophysical Implications of Ice Sputtering," Nuclear Instruments and Methods in Physics Research, B14 , Amsterdam, North Holland, p. 373, 1986.

Lanzerotti, L.J., and R.E. Johnson, "Astrophysical Implications of Ions Incident on Insulators," Ion Beam Modification of Insulating Materials, P. Mazzoldi and G.W. Arnold (Eds.), Amsterdam, 1986.

Lanzerotti, L.J., and S.M. Krimigis, "Comparative Magnetospheres," APL Tech. Digest, Vol. 7, p. 383, 1986.

Paonessa, M., and A.F. Cheng, "Limits on Ion Radial Diffusion Coefficients in Saturn's Inner Magnetosphere," J. Geophys. Res ., Vol. 91, p. 1391, 1986.

Behannon, K.W., M.L. Goldstein, R.P. Lepping, H.K. Wong, B.H. Mauk, and S.M. Krimigis, "Low Frequency Waves and Associated Energetic Ions Downstream of Saturn," J. Geophys. Res ., Vol. 90, p. 10791, 1985.

Brown, D.C., "Observations of Sunward and Tailward Ion Streaming in the Magnetotail of Jupiter with Voyager 2," Ph.D. Thesis, Dept. of Physics and Astronomy, Physics Paper 86-160, U. of Maryland, 1985.

Cheng, A.F., "Magnetospheric Interchange Instability," J. Geophys. Res ., Vol. 91, p. 9900, 1985.

Cheng, A.F., S.M. Krimigis, and T.P. Armstrong, "Near Equality of Ion Phase Space Densities at Earth, Jupiter, and Saturn," J. Geophys. Res ., Vol. 90, p. 526, 1985.

Cheng, A.F., L.J. Lanzerotti, and C.G. Maclennan, "Does Saturn Have Rings Outside 10R(S)?," Nature , Vol. 317, p. 508, 1985.

Cheng, A.F., and M.T. Paonessa, "A Theory of Satellite Sweeping," J. Geophys. Res ., Vol. 90, p. 3428, 1985.

Gold, R.E., L.J. Lanzerotti, C.G. Maclennan, and S.M. Krimigis, "Latitude Dependence of Corotating Shock Acceleration," 19th Intl. Cosmic Ray Conf. Proc. , San Diego, 1985.

Gold, R.E., L.J. Lanzerotti, C.G. Maclennan, and S.M. Krimigis, "Latitude Dependence of Corotating Shock Acceleration in the Outer Heliosphere," ESLAB Proceedings , Les Diablarets, Switzerland, 1985.

Gold, R.E., and D. Venkatesan, "Longitudinal Distribution of Cosmic Rays in the Heliosphere," 19th Intl. Cosmic Ray Conf. Proc. , San Diego, Vol. 4, p. 405, 1985.

Hamilton, D.C., G.M. Mason, and G. Gloeckler, "Constraints on Solar Flare Particle Transport Models from Anisotropy Observations at Voyager 1," 19th Intl. Cosmic Ray Conf. Proc. , Vol. 4, p. 321, 1985.

Johnson, R.E., L.A. Barton, J.W. Boring, W.A. Jesser, W.L. Brown, and L.J. Lanzerotti, "Charged Particle Modification of Ices in the Saturnian and Jovian Systems," Ices in the Solar System, J. Klinger, et al. (Eds.), D. Reidel Publishing Co., 1985.

Krimigis, S.M., R.D. Zwickl, and D.N. Baker, "Energetic Ions Upstream of Jupiter's Bow Shock," J. Geophys. Res ., Vol. 90, p. 3947, 1985.

Krimigis, S.M., and E.T. Sarris, "Acceleration of Ions and Electrons to Near-Cosmic Ray Energies in a Perpendicular Shock: The January 6, 1978 Event," 19th Intl. Cosmic Ray Conf. Proc. , Vol. 4, p. 170, 1985.

Lanzerotti, L.J., W.L. Brown, and R.E. Johnson, "Laboratory Studies of Ion Radiation of Water, Sulfur Dioxide, and Methane Ice," J. Klinger, et al. (Eds.), D. Reidel Publishing Co., 1985.

Lanzerotti, L.J., and S.M. Krimigis, "Comparative Magnetospheres," Phys. Today , Vol. 38, p. 25, 1985.

Lanzerotti, L.J., C.G. Maclennan, and R.E. Gold, "Interplanetary Conditions During 3 kHz Radio Wave Detections in the Outer Heliosphere," Nature , Vol. 316, p. 243, 1985.

Lanzerotti, L.J., C.G. Maclennan, R.E. Gold, and S.M. Krimigis, "Latitude Dependence of Co-rotating Shock Acceleration," 19th Intl. Cosmic Ray Conf. Proc. , Vol. 4 , p. 186, 1985.

Mason, G.M., D.C. Hamilton, G. Gloeckler, and B. Klecker, "Radial Transport of 1 MeV/Nucleon Ions During the November 22, 1977 Solar Particle Event," 19th International Cosmic Ray Conference Papers, NASA Science and Tech. Info. Branch , Vol. 4, p. 347, 1985.

Mauk, B.H., S.M. Krimigis, and R.P. Lepping, "Particle and Field Stress Balance Within a Planetary Magnetosphere," J. Geophys. Res ., Vol. 90, p. 8253, 1985.

Paonessa, M., "Voyager Observations of Ion Phase Space Densities in the Jovian Magnetosphere," J. Geophys. Res ., Vol. 90, p. 521, 1985.

Sarris, E.T., and S.M. Krimigis, "Multispacecraft Observations of the East-West Asymmetry of Solar Energetic Storm Particle Events," Solar Phys ., Vol. 96, p. 413, 1985.

Sarris, E.T., and S.M. Krimigis, "Quasi-Perpendicular Shock Acceleration of Ions to ~2 MeV Observed by Voyager 2," Astrophys. J .,Vol. 298, p. 676, 1985.

Sarris, E.T., R.B. Decker, and S.M. Krimigis, "Deep Space Observations of the E-W Asymmetry of Solar ESP Events: Voyagers 1 and 2," J. Geophys. Res ., Vol. 90, p. 3961, 1985.

Schardt, A.W., W.S. Kurth, R.P. Lepping, and C.G. Maclennan, "Particle Acceleration in Saturn's Outer Magnetosphere," J. Geophys. Res ., Vol. 90, p. 8539, 1985.

Tariq, G.F., T.P. Armstrong, and J.W. Lowry, "Electrodynamic Interaction of Ganymede with the Jovian Magnetosphere and the Radial Spread of Wake-Associated Disturbances," J. Geophys. Res ., Vol. 90, p. 3995, 1985.

Venkatesan, D., R.B. Decker, and S.M. Krimigis, "Voyager 1 and 2 Measurements of Radial and Latitudinal Cosmic Ray Gradients During 1981-84.," 19th Intl. Cosmic Ray Conf. Proc. , Vol. 4, p. 170, 1985.

Baker, D.N., R.D. Zwickl, S.M. Krimigis, J.F. Carbary, and M.H. Acuña, "Energetic Particle Transport in the Upstream Region of Jupiter: Voyager Results," J. Geophys. Res ., Vol. 89, p. 3775, 1984.

Cheng, A.F., "Magnetospheres, Moons, and Rings of Uranus," Uranus and Neptune, J. Bergstralh (Ed.), NASA Conf. Publ. CP-2330, p. 541, 1984.

Cheng, A.F., "Adiabatic Theory in Rapidly Rotating Magnetospheres," J. Geophys. Res ., Vol. 89, p. 5453, 1984.

Cheng, A.F., "Escape of Sulfur and Oxygen from Io," J. Geophys. Res ., Vol. 89, p. 3939, 1984.

Cheng, A.F., M.T. Paonessa, C.G. Maclennan, L.J. Lanzerotti, and T.P. Armstrong, "Longitudinal Asymmetry in the Io Plasma Torus," J. Geophys. Res ., Vol. 89, p. 3005, 1984.

Cheng, A.F., and T.W. Hill, "Do the Satellites of Uranus Control its Magnetosphere?," Uranus and Neptune, J.T. Bergstralh (Ed.), NASA Conf. Publ. CP-2330, p. 557, 1984.

Decker, R.B., S.M. Krimigis, and D. Venkatesan, "Estimate of Cosmic Ray Latitudinal Gradient," Astrophys. J. Lett .,Vol. 279, p. 119, 1984.

Fan, C.Y., G. Gloeckler, and D. Hovestadt, "The Composition of Heavy Ions in Solar Energetic Particle Events," Space Sci. Rev ., Vol. 83, p. 124, 1984.

Johnson, R.E., L.A. Barton, W.A. Jesser, L.J. Lanzerotti, and W.L. Brown, "Charged Particle Modification of Ices in the Saturnian and Jovian Systems," Proceedings of NATO Advanced Research Workshop on "Ices in the Solar System ," Nice, France, 1984.

Johnson, R.E., L.J. Lanzerotti, and W.L. Brown, "Sputtering Process: Erosion and Chemical Change," Adv. Space Res ., Vol. 4, p. 41, 1984.

Lanzerotti, L.J., W.L. Brown, and R.E. Johnson, "Laboratory Studies of Ion Irradiation of Water, Sulfur Dioxide, and Methane Ices," Proceedings of NATO Advanced Research Workshop on "Ices in the Solar System ," Nice, France, 1984.

Scarf, F.L., L.A. Frank, D.A. Gurnett, L.J. Lanzerotti, A. Lazarus, and E.C. Sittler, Jr., "Measurements of Plasma, Plasma Waves, and Suprathermal Charged Particles in Saturn's Inner Magnetosphere," Saturn, T. Gehrels and M. Matthews (Eds.), U. of Arizona Press, p. 318, 1984.

Tariq, G.F., "Voyager 2 Encounter with Ganymede's Wake: Hydrodynamic and Electrodynamic Processes," Ph.D. Thesis, Dept. of Physics, U. of Kansas, 1984.

Venkatesan, D., R.B. Decker, and S.M. Krimigis, "Radial Gradient of Cosmic Ray Intensity from a Comparative Study of Data from Voyagers 1 and 2 and IMP-8," J. Geophys. Res ., Vol. 89, p. 3735, 1984.

Venkatesan, D., R.B. Decker, and S.M. Krimigis, "Cosmic Ray Inten. Gradients in the Radial Dist. 1-13 AU as Deter. from a Comp. Stud. of Observs. by Spacecraft VGRs 1&2, and Earth-Orb. IMP-8," 18th Intl. Cosmic Ray Conf. Proc. , Vol. 10, p. 156, 1984.

Venkatesan, D., R.B. Decker, and S.M. Krimigis, "Radial Gradient of Cosmic Ray Intensity from a Comparative Study of Data from Voyager 1 and 2 and IMP8," J. Geophys. Res ., Vol. 89, p. 3735, 1984.

Armstrong, T.P., M.T. Paonessa, E.V. Bell, and S.M. Krimigis, "Voyager Observations of Saturnian Ion and Electron Phase Space Densities," J. Geophys. Res ., Vol. 88, p. 8893, 1983.

Baker, D.N., R.D. Zwickl, J.F. Carbary, S.M. Krimigis, and R.P. Lepping, "Energetic Ion Acceleration and Transport in the Upstream Region of Jupiter: Voyager 1 and 2," Adv. Space Res ., Vol. 3, p. 77, 1983.

Carbary, J.F., B.H. Mauk, and S.M. Krimigis, "Corotation Anisotropies in Saturn's Magnetosphere," J. Geophys. Res ., Vol. 88, p. 8937, 1983.

Carbary, J.F., S.M. Krimigis, and W.H. Ip, "Energetic Particle Microsignatures of Saturn's Satellites," J. Geophys. Res ., Vol. 88, p. 8947, 1983.

Cheng, A.F., "Thin, Rotating Plasma Disks," J. Geophys. Res ., Vol. 88, p. 13, 1983.

Cheng, A.F., C.G. Maclennan, L.J. Lanzerotti, M.T. Paonessa, and T.P. Armstrong, "Energetic Ion Losses Near Io's Orbit," J. Geophys. Res ., Vol. 88, p. 3936, 1983.

Hamilton, D.C., D.C. Brown, G. Gloeckler, and W.I. Axford, "Energetic Atomic and Molecular Ions in Saturn's Magnetosphere," J. Geophys. Res ., Vol. 88, p. 8905, 1983.

Hamilton, D.C., and G. Gloeckler, "The September 1979 Solar Cosmic Ray Event," 18th Intl. Cosmic Ray Conf. Proc. , 1983.

Johnson, R.E., J.W. Boring, C.T. Reimann, L.A. Barton, E.M. Sieveka, J.W. Garrett, K.R. Farmer, W.L. Brown, and L.J. Lanzerotti, "Plasma-Ion Induced Molecular Ejection on the Galilean Satellites: Ejected Molecule Energies," Geophys. Res. Lett ., Vol. 10, p. 892, 1983.

Johnson, R.E., W.L. Brown, and L.J. Lanzerotti, "Energetic Charged Particle Erosion of Ices in the Solar System," J. Phys. Chem ., Vol. 87, p. 4218, 1983.

Krimigis, S.M., J.F. Carbary, E.P. Keath, T.P. Armstrong, L.J. Lanzerotti, and G. Gloeckler, "General Characteristics of Hot Plasma and Energetic Particles in the Saturnian Magnetosphere: Results from the Voyager Spacecraft," J. Geophys. Res ., Vol. 88, p. 8871, 1983.

Krimigis, S.M., and E.C. Roelof, "Low Energy Particle Population," Physics of the Jovian Magnetosphere, A. Dessler (Ed.), Cambridge U. Press, England, p. 106, 1983.

Lanzerotti, L.J., "Supply of SO(2) for the Atmosphere of Io," J. Geophys. Res ., Vol. 88, p. 989, 1983.

Lanzerotti, L.J., C.G. Maclennan, R.P. Lepping, and S.M. Krimigis, "On the Plasma Conditions at the Dayside Magnetopause of Saturn," Geophys. Res. Lett ., Vol. 10, p. 1200, 1983.

Lanzerotti, L.J., C.G. Maclennan, W.L. Brown, R.E. Johnson, L.A. Barton, C.T. Reimann, J.W. Garrett, and J.W. Boring, "Implications of Voyager Data for Energetic Ion Erosion of the Icy Satellites of Saturn," J. Geophys. Res ., Vol. 88, p. 8765, 1983.

Maclennan, C.G., L.J. Lanzerotti, S.M. Krimigis, and R.P. Lepping, "Low Energy Particles at the Bow Shock and Magnetopause of Saturn," J. Geophys. Res ., Vol. 88, p. 8817, 1983.

Roelof, E.C., R.B. Decker, and S.M. Krimigis, "Latitudinal and Field-Aligned Cosmic Ray Gradients 2-5 AU: Voyagers 1 and 2 and IMP-8," J. Geophys. Res ., Vol. 88, p. 9889, 1983.

Tariq, G.F., T.P. Armstrong, and T.H. Collison, "Voyager 2 Observations of Energetic Particle Variations in the Ganymede Wake Region: A Possible Acceleration Mechanism," J. Geophys. Res ., Vol. 88, p. 5551, 1983.

Brown, W.L., L.J. Lanzerotti, and R.E. Johnson, "Fast Ion Bombardment of Ices and Its Astrophysical Implications," Science, Vol. 218, p. 525, 1982.

Carbary, J.F., and S.M. Krimigis, "Charged Particle Periodicity in the Saturnian Magnetosphere," Geophys. Res. Lett ., Vol. 9, p. 1073, 1982.

Cheng, A.F., "SO(2) Ionization and Dissociation in the Io Plasma Torus," J. Geophys. Res ., Vol. 87, p. 5301, 1982.

Cheng, A.F., L.J. Lanzerotti, and V. Pirronello, "Charged Particle Sputtering of Ice Surfaces in Saturn's Magnetosphere," J. Geophys. Res ., Vol. 87, p. 4567, 1982.

Cheng, A.F., L.J. Lanzerotti, and V. Pirronello, "On the Lifetime of E-Ring Grains and Their Nature," Sun and Planetary System, W. Fricke and G. Teleki (Eds.), D. Reidel Publishing Co., p. 251, 1982.

Johnson, R.E., L.J. Lanzerotti, and W.L. Brown, "Planetary Applications of Ion-Induced Erosion of Condensed-Gas Frosts," Nucl. Instrum. Meth ., p. 147, 1982.

Krimigis, S.M., "Voyager Encounters with Jupiter's Magnetosphere: Results of the Low Energy Charged Particle (LECP) Experiment," Compendium in Astronomy , Mariolopoulos, et. al. (Eds.), Reidel Publishers, Holland, p. 191, 1982.

Krimigis, S.M., "A Post-Voyager View of Saturn's Environment," APL Tech. Digest, Vol. 3, p. 180, 1982.

Krimigis, S.M., and T.P. Armstrong, "Two Component Proton Spectra in the Inner Saturnian Magnetosphere," Geophys. Res. Lett ., Vol. 9, p. 1143, 1982.

Krimigis, S.M., T.P. Armstrong, W.I. Axford, C.O. Bostrom, G. Gloeckler, E.P. Keath, L.J. Lanzerotti, J.F. Carbary, D.C. Hamilton, and E.C. Roelof, "Low Energy Hot Plasma and Particles in Saturn's Magnetosphere," Science, Vol. 215, p. 571, 1982.

Kutchko, F.J., P.R. Briggs, and T.P. Armstrong, "The Bidirectional Particle Event of October 12, 1977, Possibly Associated with a Magnetic Loop," J. Geophys. Res ., Vol. 87, p. 1419, 1982.

Lanzerotti, L.J., W.L. Brown, W.M. Augustyniak, R.E. Johnson, and T.P. Armstrong, "Laboratory Studies of Charged Particle Erosion of SO(2) Ice and Applications to the Frosts of Io," Astrophys. J ., Vol. 259, p. 920, 1982.

Maclennan, C.G., L.J. Lanzerotti, S.M. Krimigis, R.P. Lepping, and N.F. Ness, "Effects of Titan on Trapped Particles in Saturn's Magnetosphere," J. Geophys. Res ., Vol. 87, p. 1411, 1982.

Armstrong, T.P., M.T. Paonessa, S.T. Brandon, S.M. Krimigis, and L.J. Lanzerotti, "Low Energy Charged Particle Observations in the 5-20 R(J) Region of the Jovian Magnetosphere," J. Geophys. Res ., Vol. 86, p. 8343, 1981.

Carbary, J.F., S.M. Krimigis, E.P. Keath, G. Gloeckler, W.I. Axford, and T.P. Armstrong, "Ion Anisotropies in the Outer Jovian Magnetosphere," J. Geophys. Res ., Vol. 86, p. 8285, 1981.

Carbary, J.F., and S.M. Krimigis, "Low Energy Charged Particles at Saturn," APL Tech. Digest, Vol. 2, p. 87, 1981.

Decker, R.B., M.E. Pesses, and S.M. Krimigis, "Shock-Associated Low-Energy Ion Enhancements Observed by Voyagers 1 and 2," J. Geophys. Res ., Vol. 86, p. 8819, 1981.

Hamilton, D.C., G. Gloeckler, S.M. Krimigis, and L.J. Lanzerotti, "Composition of Non-Thermal Ions in the Jovian Magnetosphere," J. Geophys. Res ., Vol. 86, p. 8301, 1981.

Hamilton, D.C., and G. Gloeckler, "Evolution of the Energetic Particle Composition During the November 1977 Solar Flare Event as Observed by Voyager 2," 17th Intl. Cosmic Ray Conf. Proc. , Vol. 10, p. 49, 1981.

Johnson, R.E., L.J. Lanzerotti, W.L. Brown, and T.P. Armstrong, "Erosion of Galilean Satellite Surfaces by Jovian Magnetospheric Particles," Science, Vol. 212, p. 1027, 1981.

Kirsch, E.S., S.M. Krimigis, J.W. Kohl, and E.P. Keath, "Upper Limits for X-ray and Energetic Neutral Particle Emission from Jupiter: Voyager 1 Results," Geophys. Res. Lett ., Vol. 8, p. 169, 1981.

Kirsch, E.S., S.M. Krimigis, W.H. Ip, and G. Gloeckler, "X-ray and Energetic Neutral Particle Emission from Saturn's Magnetosphere," Nature , Vol. 292, p. 718, 1981.

Krimigis, S.M., "A Post-Voyager View of Jupiter's Magnetosphere," Endeavour , Vol., 5, p. 50, 1981.

Krimigis, S.M., "Planetary Magnetospheres: The In Situ Astrophysical Laboratories," 17th Intl. Cosmic Ray Conf. Proc. , Vol. 12, p. 229, 1981.

Krimigis, S.M., J. F. Carbary, E. P. Keath, C.O. Bostrom, W.I. Axford, G. Gloeckler, L.J. Lanzerotti, and T.P. Armstrong, "Characteristics of Hot Plasma in the Jovian Magnetosphere: Results from the Voyager Spacecraft," J. Geophys. Res ., Vol. 86, p. 8227, 1981.

Krimigis, S.M., T.P. Armstrong, W.I. Axford, C.O. Bostrom, G. Gloeckler, E.P. Keath, L.J. Lanzerotti, J.F. Carbary, D.C. Hamilton, and E.C. Roelof, "Low-Energy Charged Particles in Saturn's Magnetosphere: Results from Voyager 1," Science, Vol. 212, p. 225, 1981.

Lanzerotti, L.J., C.G. Maclennan, T.P. Armstrong, S.M. Krimigis, R.P. Lepping, and N.F. Ness, "Ion and Electron Angular Distributions in the Io Torus Region of the Jovian Magnetosphere," J. Geophys. Res ., Vol. 86, p. 8491, 1981.

Zwickl, R.D., S.M. Krimigis, J.F. Carbary, E.P. Keath, T.P. Armstrong, D.C. Hamilton, and G. Gloeckler, "Energetic Particle Events ( 30 keV) of Jovian Origin Observed by Voyager 1 and 2 in Interplanetary Space," J. Geophys. Res ., Vol. 86, p. 8125, 1981.

Burlaga, L.F., R.P. Lepping, R. Weber, T.P. Armstrong, C.C. Goodrich, J.D. Sullivan, D.A. Gurnett, P. Kellogg, E. Keppler, F. Mariani, F.M. Neubauer, H. Rosenbauer, and R. Schwenn, "Interplanetary Particles & Fields, Nov. 22, 1977 - Dec. 7, 1977: Helios, Voyager, and IMP Observations Between 0.6 AU and 1.6 AU," J. Geophys. Res ., Vol. 85, p. 2227, 1980.

Carbary, J.F., "Periodicities in the Jovian Magnetosphere: Magnetodisc Models After Voyager," Geophys. Res. Lett ., Vol. 7, p. 29, 1980.

Carbary, J.F., and S.M. Krimigis, "Encounters with Jupiter: The Low Energy Charged Particle Results of Voyager," APL Tech. Digest, Vol. 1, p. 60, 1980.

Cheng, A.F., "Effects of Io's Volcanoes on the Plasma Torus and Jupiter's Magnetosphere," Astrophys. J ., Vol. 242, p. 212, 1980.

Hamilton, D.C., G. Gloeckler, S.M. Krimigis, C.O. Bostrom, T.P. Armstrong, W.I. Axford, C.Y. Fan, L.J. Lanzerotti, and D.M. Hunten, "Detection of Energetic Hydrogen Molecules in Jupiter's Magnetosphere by Voyager 2: Evidence for an Ionospheric Plasma Source," Geophys. Res. Lett ., Vol. 7, p. 813, 1980.

Krimigis, S.M., T.P. Armstrong, W.I. Axford, C.O. Bostrom, C.Y. Fan, G. Gloeckler, L.J. Lanzerotti, D.C. Hamilton, and R.D. Zwickl, "Energetic (~100 keV) Tailward-Directed Ion Beam Outside the Jovian Plasma Boundary," Geophys. Res. Lett ., Vol. 7, p. 13, 1980.

Lanzerotti, L.J., C.G. Maclennan, R.P. Lepping, and S.M. Krimigis, "Intensity Variations in Plasma Flow at the Dawn Magnetopause," Planet. Space Sci . Vol. 28, p. 1163, 1980.

Lanzerotti, L.J., C.G. Maclennan, S.M. Krimigis, T.P. Armstrong, K.W. Behannon, and N.F. Ness, "Statics of the Nightside Jovian Plasma Sheet," Geophys. Res. Lett ., Vol. 7, p. 817, 1980.

Zwickl, R.D., S.M. Krimigis, T.P. Armstrong, and L.J. Lanzerotti, "Ions of Jovian Origin Observed by Voyager 1 and 2 in Interplanetary Space," Geophys. Res. Lett ., Vol. 7, p. 453, 1980.

Hamilton, D.C., G. Gloeckler, T.P. Armstrong, W.I. Axford, C.O. Bostrom, C.Y. Fan, S.M. Krimigis, and L.J. Lanzerotti, "Recurrent Energetic Particle Events Associated with Forward/Reverse Shock Pairs Near 4 AU in 1978," 16th Intl. Cosmic Ray Conf. Proc., Vol. 5, p. 363, 1979.

Krimigis, S.M., T.P. Armstrong, W.I. Axford, C.O. Bostrom, C.Y. Fan, G. Gloeckler, L.J. Lanzerotti, E.P. Keath, R.D. Zwickl, J.F. Carbary, and D.C. Hamilton, "Low-Energy Charged Particle Environment at Jupiter - A First Look," Science, Vol. 204, p. 998, 1979.

Krimigis, S.M., T.P. Armstrong, W.I. Axford, C.O. Bostrom, C.Y. Fan, G. Gloeckler, L.J. Lanzerotti, E.P. Keath, R.D. Zwickl, J.F. Carbary, and D.C. Hamilton, "Hot Plasma Environment at Jupiter: Voyager 2 Results," Science, Vol. 206, p. 977, 1979.

Lanzerotti, L.J., S.M. Krimigis, C.O. Bostrom, W.I. Axford, R.P. Lepping, and N.F. Ness, "Measurements of Plasma Flow at the Dawn Magnetopause," J. Geophys. Res ., Vol. 84, p. 6483, 1979.

Cheng, A.F., and L.J. Lanzerotti, "Ice Sputtering by Radiation Belt Protons and the Rings of Saturn and Uranus," J. Geophys. Res ., Vol. 83, p. 2397, 1978.

Lanzerotti, L.J., W.L. Brown, J.M. Poate, and W.M. Augustyniak, "On the Contributions of Water Products from Galilean Satellites to the Jovian Magnetosphere," Geophys. Res. Lett ., Vol. 5, p. 155, 1978.

Krimigis, S.M., T.P. Armstrong, W.I. Axford, C.O. Bostrom, C.Y. Fan, G. Gloeckler, and L.J. Lanzerotti, "The Low Energy Charged Particle (LECP) Experiment on the Voyager Spacecraft," Space Sci. Rev ., Vol. 21, p. 329, 1977.

IMAGES

  1. Ring-Moon Systems Node

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  2. The Low Energy Particle Instruments on the Voyager Spacecraft

    lecp voyager

  3. NASA’S Voyager 1 Cruising on a ‘Magnetic Highway’

    lecp voyager

  4. Voyager LECP Data

    lecp voyager

  5. Definition of Voyager 1 LECP Channels and Flux Boxes Used Herein

    lecp voyager

  6. Response of the Voyager 2 LECP/LEMPA/α detector, found through Equation

    lecp voyager

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COMMENTS

  1. Voyager

    The LECP looks for particles of higher energy than the PLS, and it overlaps with the Cosmic Ray Subsystem (CRS). It has the broadest energy range of the three sets of particle sensors. The LECP can be imagined as a piece of wood, with the particles of interest playing the role of bullets. The faster a bullet moves, the deeper it will penetrate ...

  2. Voyager

    Voyager's 30-Year Plan. The Voyager Interstellar Mission has the potential for obtaining useful interplanetary, and possibly interstellar, fields, particles, and waves science data until around the year 2020 when the spacecraft's ability to generate adequate electrical power for continued science instrument operation will come to an end.

  3. Voyager LECP

    VOYAGER. Overview: Fundamental Technologies, LLC, provides data products for the Low Energy Charged Particle (LECP) instruments on the Voyager spacecrafts. The LECP instruments measure the intensity, energy spectra, composition, angular distributions, and spatial and temporal characteristics of ions and electrons that are encountered by the ...

  4. Voyager LECP Data

    This website presents flux averages from the Low Energy Charged Particle instruments on Voyager 1 and Voyager 2. The PHA data (pulse height analysis) from the LECP instruments have been analyzed to compute 26-day, 52-day, and annual flux averages for several species as a function of energy. All data returned in the Cruise 5a format are included.

  5. Voyager

    The Voyager Interstellar Mission has the potential for obtaining useful interplanetary, and possibly interstellar, fields, particles, and waves science data until around the year 2025 when the spacecraft's ability to generate adequate electrical power for continued science instrument operation will come to an end. › Find out more Fast Facts

  6. The Low Energy Charged Particle (Lecp) Experiment on The Voyager Spacecraft

    Abstract. The Low Energy Charged Particle (LECP) experiment on the Voyager spacecraft is designed to provide comprehensive measurements of energetic particles in the Jovian, Saturnian, Uranian and interplanetary environments. These measurements will be used in establishing the morphology of the magnetospheres of Saturn and Uranus, including bow ...

  7. PDF Encounters With Jupiter: the Low Energy Charged Particle Results of Voyager

    In the outer magnetosphere, the Voyager LECP's discovered extremely hot, corotating plasma. Max­ wellian fits to the observed spectra revealed tem­ peratures of 20 to 30 keY (about 2.5 x 108 K) and flow speeds of up to about 1000 km/s. Though much hotter than the solar corona (at about

  8. Energetic charged particle measurements from Voyager 2 at the ...

    Voyager 2's heliopause crossing bears some similarity to that of Voyager 1, despite differing solar wind conditions. ... The Low Energy Charged Particle (LECP) experiment on the Voyager ...

  9. index.html

    Voyager LECP Home Page. The Low Energy Charged Particle (LECP) instruments aboard the Voyager 1 and 2 spacecraft make composition measurements of energetic particles above about 0.3 MeV/nucleon. Using one or both of the LECP instruments, observations have been made of magnetospheric ions during each of the four Voyager planetary encounters ...

  10. Low-Energy Charged Particle Detector (LECP)

    Instrument Characteristics. The low energy charged particle experiment employs a set of solid state detectors arranged to characterize, with various levels of energy, directional, and compositional discriminations, the in-situ charged particle environment of the spacecraft, both within interplanetary and planetary magnetospheric regions.

  11. The Low Energy Particle Instruments on the Voyager Spacecraft

    The LECP has also been used to determine the environment of the Voyager 1 probe. When Voyager 1 entered interstellar space, detected galactic cosmic rays increased significantly, while protons originating from the sun virtually became undetectable. Particle measurements that indicated Voyager 1 was crossing the boundary of the solar system.

  12. LECP

    The LECP on Voyager 1 sensed the termination shock — the region where the Sun's solar wind of charged particles slows to subsonic speeds because of interactions with the local interstellar medium — in December 2004, and the LECP on Voyager 2 sensed it in August 2007. LECP was one of two instruments that also detected the dramatic switch ...

  13. The Low Energy Charged Particle (LECP) experiment on the Voyager

    The Low Energy Charged Particle (LECP) experiment on the Voyager spacecraft is designed to provide comprehensive measurements of energetic particles in the Jovian, Saturnian, Uranian and interplanetary environments. These measurements will be used in establishing the morphology of the magnetospheres of Saturn and Uranus, including bow shock, magnetosheath, magnetotail, trapped radiation, and ...

  14. Voyager

    Roelof, E.C., R.B. Decker, and S.M. Krimigis, Voyager 1/LECP Energetic Ion Angular Distributions at 85-88 AU are Inconsistent with Diffusion-Convection Theory, 35 th COSPAR Scientific Assembly, Abstract COSPAR04-A-03516, 2004. 2003. Anagnostopoulos G. C., A New Region in the Jovian ...

  15. Overview of the Voyager Mission and the LECP Investigation

    VOYAGER. Voyager LECP Data Analysis Handbook . Overview of the Voyager Mission and the LECP Investigation . The Voyager 1 and Voyager 2 spacecraft were launched from Cape Canaveral, Florida, during the summer of 1977. They were originally designed to conduct closeup studies of Jupiter and Saturn during their 5-year missions.

  16. Le bug persistant de Voyager 1 inquiète : « C'est un problème grave

    Voyager 1 restait néanmoins capable de recevoir et d'exécuter les commandes émises depuis la Terre. ... « Franchement, je suis très inquiet », complète Stamatios Krimigis, astronome et spécialiste de l'instrument LECP (capteur de particules faible énergie) sur Voyager 1 et 2. Vue d'artiste d'une sonde Voyager proche de Saturne ...

  17. Active carbons as nanoporous materials for solving of environmental

    Catalysis Conference is a networking event covering all topics in catalysis, chemistry, chemical engineering and technology during October 19-21, 2017 in Las Vegas, USA. Well noted as well attended meeting among all other annual catalysis conferences 2018, chemical engineering conferences 2018 and chemistry webinars.

  18. Voyager LECP

    Voyager LECP DATA Fundamental Technologies, LLC, provides data products for the Low Energy Charged Particle (LECP) instruments on the Voyager spacecrafts. The LECP instruments measure the intensity, energy spectra, composition, angular distributions, and spatial and temporal characteristics of ions and electrons that are encountered by the ...

  19. Rosatom Starts Life Tests of Third-Generation VVER-440 Nuclear Fuel

    Dukovany NPP with 2040 MWe of installed capacity has four power units powered by VVER-440 reactors which were commissioned one by one in 1985-1987. The plant generates about 13 billion kWh of electricity annually covering approximately 20% of power consumption in the Czech Republic. Together with Temelin NPP (two units with VVER-1000), ČEZ ...

  20. Voyager

    Instrument Status. This is a real-time indicator of Voyagers' distance from Earth in astronomical units (AU) and either miles (mi) or kilometers (km). Note: Because Earth moves around the sun faster than Voyager 1 is speeding away from the inner solar system, the distance between Earth and the spacecraft actually decreases at certain times of year.

  21. First refuelling for Russia's Akademik Lomonosov floating NPP

    Rosatom's fuel company TVEL has supplied nuclear fuel for reactor 1 of the world's only floating NPP (FNPP), the Akademik Lomonosov, moored at the city of Pevek, in Russia's Chukotka Autonomous Okrug. The supply of fuel was transported along the Northern Sea Route. The first ever refuelling of the FNPP is planned to begin before the end of ...

  22. Voyager

    The Photopolarimeter Subsystem uses a 0.2 m telescope fitted with filters and polarization analyzers. It covers eight wavelengths in the region between 235 nm and 750 nm. The experiment is designed to determine the physical properties of particulate matter in the atmospheres of Jupiter, Saturn, and the Rings of Saturn by measuring the intensity ...

  23. Strange Glow Over Moscow Skies Triggers Panic as Explosions Reported

    B right flashes lit up the night sky in southern Moscow in the early hours of Thursday morning, new footage appears to show, following reports of an explosion at an electrical substation on the ...

  24. Voyager

    Hill, M.E., "Methods of Analysis for Voyager LECP Data," Scholarly paper required by the Dept. of Physics, Univ. of Maryland, for the M.S. degree and for admission to candidacy for the Ph.D. degree,149 pages, June 1998.