DOCSLIB.ORG

Space Missions to the Outer Planets

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Space Missions to the Outer Planets Space Research Institute Graz Austrian Academy of Sciences Exploring the Planets and Moons in our Solar System Helmut O. Rucker CERN, Geneve, June 2006 Space Research Institute Graz Austrian Academy of Sciences Exploring the Planets and Moons in our Solar System • The interplanetary medium, the solar wind and its interaction with magnetized planets CERN, Geneve, June 2006 Space Research Institute Graz Austrian Academy of Sciences Exploring the Planets and Moons in our Solar System • The interplanetary medium, the solar wind and its interaction with magnetized planets • Space missions to the outer planets CERN, Geneve, June 2006 Space Research Institute Graz Austrian Academy of Sciences Exploring the Planets and Moons in our Solar System • The interplanetary medium, the solar wind and its interaction with magnetized planets • Space missions to the outer planets • Specific aspects of magnetospheric physics – radio emission CERN, Geneve, June 2006 Space Research Institute Graz Austrian Academy of Sciences Exploring the Planets and Moons in our Solar System • The interplanetary medium, the solar wind and its interaction with magnetized planets • Space missions to the outer planets • Specific aspects of magnetospheric physics – radio emission • Volcanoes and icy worlds CERN, Geneve, June 2006 Space Research Institute Graz Austrian Academy of Sciences Exploring the Planets and Moons in our Solar System • The interplanetary medium, the solar wind and its interaction with magnetized planets • Space missions to the outer planets • Specific aspects of magnetospheric physics – radio emission • Volcanoes and icy worlds • Space Missions to the terrestrial planets CERN, Geneve, June 2006 Space Research Institute Graz Austrian Academy of Sciences The interplanetary medium, the solar wind and its interaction with magnetized planets Helmut O. Rucker CERN, Geneve, June 2006 The central star of our solar system – the Sun Mass loss by the expanding solar atmosphere, i.e. the solar wind: ~ 1 Mill. tons per second Viewgraph: Helmet streamer The solar wind = expanding atmosphere of the Sun highly conducting plasma, radially propagating (300 km/s < v < 2000 km/s) r vsw The solar wind = expanding atmosphere of the Sun highly conducting plasma, radially propagating (300 km/s < v < 2000 km/s) The interplanetary magnetic field is a solar magnetic field r B drawn out of the Sun IMF by the highly conducting solar wind plasma. Due to the solar rotation a spiral structure is formed. Parker spiral: ω r tanΨ = sun vsw 2 /(ωsun 25= π . 38× 86s , 400 ) −6 − 1 ω2sun= . 86 × 10s −1 vsw = 450kms (rψ 1= . 0 AU ) = 43 ° . 6 (rψ 9= . 5 AU ) = 83 ° . 7 Solar wind average properties at r ~ 1 AU: Different types of solar wind (sw): Fast sw: 400 < v < 800 km/s, Helium 3 – 4 % Slow sw of minimum type: 250 < v < 400 km/s, Helium < 2 % Slow sw of maximum type: 250 < v < 400 km/s, Helium ~ 4 % Coronal mass ejections (CMEs): 400 < v < 2000 km/s, Helium(++) ~ 30 % Solar wind average properties at r ~ 1 AU: Dipole structure r M D 2 r= 0 rsin ϑ Interaction between the solar wind and planetary magnetic field 1 ⎛ cnk() T+ ⎞ T2 Solar wind bulk flow = super-sonic lowf ⎜ p e i ⎟ vsonic = ⎜ ⎟ ⎝ cV nm ⎠ B = super-Alfvenic lowf vA = μ0 ρ Interaction between the solar wind and planetary magnetic field Bow shock: Transition of solar wind plasma described by the Rankine Hugoniot equations. Change after transition: bulk speed particle density plasma pressure plasma temperature 3D schematics of the terrestrial magnetosphere magnetopause boundary conditions: 2 2 2 nmv cos α = B / 2μ 0 B n = 0 Magnetotail cross section at r = 20 Re Magnetic reconnection B B Magnetic reconnection B B Magnetic reconnection B B Courtesy Prange, 2006 Courtesy Prange, 2006 1st reconnection = start of the cycle Courtesy Prange, 2006 Courtesy Prange, 2006 Courtesy Prange, 2006 transport over the poles Courtesy Prange, 2006 Courtesy Prange, 2006 2nd reconnection Courtesy Prange, 2006 impulsive acceleration Release of energy ( the stretched configuration contains additional energy to accelerate plasma) Courtesy Prange, 2006 ejection of plasma into the magnetotail Courtesy Prange, 2006 returning of a « magnetic loop » back to the dayside Courtesy Prange, 2006 Courtesy Prange, 2006 dawn Inner-magnetospheric electric fields dusk dawn Inner-magnetospheric particle drift paths and plasmasphere iso-potential lines, resp. dusk Cluster Double Star Themis MMS PLANETARY AURORAE a fascinating phenomenon at and around the magnetic poles of magnetized planets Earth Jupiter Saturn Dynamic Explorer ) HST-STIS HST-STIS UV - 130 nm UV - 150 nm UV - 130 nm (Courtesy . L. Frank) (R. Prangé & L Pallier) (R. Prangé & L Pallier) PLANETARY AURORAE a fascinating phenomenon at and around the magnetic poles of magnetized planets Earth Jupiter Saturn Dynamic Explorer ) HST-STIS HST-STIS UV - 130 nm UV - 150 nm UV - 130 nm (Courtesy . L. Frank) (R. Prangé & L Pallier) (R. Prangé & L Pallier) Summary: Magnetic field representation B= − gradΦ ∞ n n+1 ⎧ m m m ⎫ rΦ r∑ =p(/) r p ⎨ P(cos ∑n ϑ [] ) gn cosϕ m+ n sin hϕ ⎬ m n=1 ⎩m=0 ⎭ Φ magnetic potential rp planetary radius m Legendre polynom Pn ϑ polar distance angle m m spherical harmonic coefficients gn , n h ϕ planetocentric longitude Magnetic properties of the magnetized planets Classification of magnetospheric structures r r r M dipole Ω n ecliptic plane, seen edge on solar wind bulk velocity t0 t0 + ½ planetary rotation r r r Ω , nr Ω, M Earth 23.45° 11.4° Jupiter 3.1° 9.6° „symmetrical“ Saturn 26.7° +/- 0° magnetospheres Magnetic field of Jupiter Classification of magnetospheric structures Uranus (1986) nr ecliptic plane, seen edge on r solar wind bulk velocity Ω r M dipole t0 t0 + ½ planetary rotation r r r Ω , nr Ω, M Uranus 97.8° 58.6° Neptune 28.3° 46.9° „oblique rotators“ Classification of magnetospheric structures Neptune (1989) r r M dipole Ω nr ecliptic plane, seen edge on solar wind bulk velocity t0 t0 + ½ planetary rotation r r r Ω , nr Ω, M Uranus 97.8° 58.6° Neptune 28.3° 46.9° „oblique rotators“ „Advertisement“ for tomorrow: Space missions to the outer planets Saturn, as seen by Cassini.
Load more

Recommended publications
  • From: "MESSENGER, SCOTT R
    The Starting Materials In: Meteorites and the Early Solar System II S. Messenger Johnson Space Center S. Sandford Ames Research Center D. Brownlee University of Washington Combined information from observations of interstellar clouds and star forming regions and studies of primitive solar system materials give a first order picture of the starting materials for the solar system’s construction. At the earliest stages, the presolar dust cloud was comprised of stardust, refractory organic matter, ices, and simple gas phase molecules. The nature of the starting materials changed dramatically together with the evolving solar system. Increasing temperatures and densities in the disk drove molecular evolution to increasingly complex organic matter. High temperature processes in the inner nebula erased most traces of presolar materials, and some fraction of this material is likely to have been transported to the outermost, quiescent portions of the disk. Interplanetary dust particles thought to be samples of Kuiper Belt objects probably contain the least altered materials, but also contain significant amounts of solar system materials processed at high temperatures. These processed materials may have been transported from the inner, warmer portions of the disk early in the active accretion phase. 1. Introduction A principal constraint on the formation of the Solar System was the population of starting materials available for its construction. Information on what these starting materials may have been is largely derived from two approaches, namely (i) the examination of other nascent stellar systems and the dense cloud environments in which they form, and (ii) the study of minimally altered examples of these starting materials that have survived in ancient Solar System materials.
    [Show full text]
  • Asteroidal Dust 423
    Dermott et al.: Asteroidal Dust 423 Asteroidal Dust Stanley F. Dermott University of Florida Daniel D. Durda Southwest Research Institute Keith Grogan NASA Goddard Space Flight Center Thomas J. J. Kehoe University of Florida There is good evidence that the high-speed, porous, anhydrous chondritic interplanetary dust particles (IDPs) collected in Earth’s stratosphere originated from short-period comets. How- ever, by considering the structure of the solar-system dust bands discovered by IRAS, we are able to show that asteroidal collisions are probably the dominant source of particles in the zodiacal cloud. It follows that a significant and probably the dominant fraction of the IDPs collected in Earth’s stratosphere also originated from asteroids. IDPs are the most primitive particles in the inner solar system and represent a class of material quite different from that in our meteorite collections. The structure, mineralogy, and high C content of IDPs dictate that they cannot have originated from the grinding down of known meteorite types. We argue that the asteroidal IDPs were probably formed as a result of prolonged mechanical mixing in the deep regoliths of asteroidal rubble piles in the outer main belt. 1. INTRODUCTION information on the nature of the particles in the preplanetary solar nebula (Bradley, 1999). Observations of microcraters In our collections on Earth, we have an abundance of on the Long Duration Exposure Facility (LDEF) confirmed meteorite samples from three major sources of extraterres- that each year Earth accretes 3 × 107 kg of dust particles, a trial material: the asteroid belt, the Moon, and Mars. Some mass influx ~100× greater than the influx associated with of the source bodies of these meteorites have experienced the much larger meteorites that have masses between 100 g major physical, chemical, and mineralogical changes since and 1000 kg.
    [Show full text]
  • Urea, Glycolic Acid, and Glycerol in an Organic Residue Produced by Ultraviolet Irradiation of Interstellar=Pre-Cometary Ice Analogs
    ASTROBIOLOGY Volume 10, Number 2, 2010 ª Mary Ann Liebert, Inc. DOI: 10.1089=ast.2009.0358 Urea, Glycolic Acid, and Glycerol in an Organic Residue Produced by Ultraviolet Irradiation of Interstellar=Pre-Cometary Ice Analogs Michel Nuevo,1,2 Jan Hendrik Bredeho¨ft,3 Uwe J. Meierhenrich,4 Louis d’Hendecourt,1 and Wolfram H.-P. Thiemann3 Abstract More than 50 stable organic molecules have been detected in the interstellar medium (ISM), from ground-based and onboard-satellite astronomical observations, in the gas and solid phases. Some of these organics may be prebiotic compounds that were delivered to early Earth by comets and meteorites and may have triggered the first chemical reactions involved in the origin of life. Ultraviolet irradiation of ices simulating photoprocesses of cold solid matter in astrophysical environments have shown that photochemistry can lead to the formation of amino acids and related compounds. In this work, we experimentally searched for other organic molecules of prebiotic interest, namely, oxidized acid labile compounds. In a setup that simulates conditions relevant to the ISM and Solar System icy bodies such as comets, a condensed CH3OH:NH3 ¼ 1:1 ice mixture was UV irradiated at *80 K. The molecular constituents of the nonvolatile organic residue that remained at room temperature were separated by capillary gas chromatography and identified by mass spectrometry. Urea, glycolic acid, and glycerol were detected in this residue, as well as hydroxyacetamide, glycerolic acid, and glycerol amide. These organics are interesting target molecules to be searched for in space. Finally, tentative mechanisms of formation for these compounds under interstellar=pre-cometary conditions are proposed.
    [Show full text]
  • The Analysis of Interplanetary Dust Particles
    WORKSHOP ON THE ANALYSIS OF INTERPLANETARY DUST PARTICLES LPI Technical Report Number 94-02 Lunar and Planetary Institute 3600 Bay Area Boulevard Houston TX 77058-1113 LPIITR--94-02 WORKSHOP ON THE ANALYSIS OF INTERPLANETARY DUST PARTICLES Edited by M. Zolensky Held at Lunar and Planetary Institute May 15-17, 1993 Sponsored by Lunar and Planetary Institute Lunar and Planetary Institute 3600 Bay Area Boulevard Houston TX 77058-1113 LPI Technical Report Number 94-02 LPIITR--94-02 Compiled in 1994 by LUNAR AND PLANETARY INSTITUTE The Institute is operated by the University Space Research Association under Contract No. NASW-4574 with the National Aeronautics and Space Administration. Material in this volume may be copied without restraint for library, abstract service, education, or personal research purposes; however, republication of any paper or portion thereof requires the written permission of the authors as well as the appropriate acknowledgment of this publication. This report may be cited as M. Zolensky, ed. (1994) Workshop on the Analysis ofInterplanetary Dust Particles. LPI Tech. Rpt. 94-02, Lunar and Planetary Institute, Houston. 62 pp. This report is distributed by ORDER DEPARTMENT Lunar and Planetary Institute 3600 Bay Area Boulevard Houston TX 77058-1113 Mail order requestors will be invoiced for the cost of shipping and handling. Cover. Backscattered electron image of a hydrated, chondritic interplanetary dust particle, measuring 17).1m across. LPT Technical Report 94-02 iii Program Saturday, May 15, 1993 7:30-8:30 a.m. Registration and Continental Breakfast 8:30 a.m.-5:00 p.m. INVITED PRESENTATIONS AND DISCUSSION TOPICS An Overview ofthe Origin and Role ofDust in the Early Solar System D.
    [Show full text]
  • Production of Cosmic Dust by Hydrous and Anhydrous Asteroids: Implications for the Production of Interplanetary Dust Particles and Micrometeorites
    40th Lunar and Planetary Science Conference (2009) 1164.pdf PRODUCTION OF COSMIC DUST BY HYDROUS AND ANHYDROUS ASTEROIDS: IMPLICATIONS FOR THE PRODUCTION OF INTERPLANETARY DUST PARTICLES AND MICROMETEORITES. G. J. Flynn 1, D. D. Durda 2, M. A. Minnick 3, and M. Strait 3. 1Dept. of Physics, SUNY-Plattsburgh, 101 Broad St., Platts- burgh, NY 12901 ([email protected]), 2Southwest Research Institute, 1050 Walnut St., Suite 300, Boul- der, CO, 80302. 3Department of Chemistry, Alma College, Alma, MI 48801 Introduction: In our Solar System the asteroid Measurements: We have performed disruption ex- belt is compositionally zoned, with the asteroids simi- periments on four hydrous meteorite targets, Murchi- lar in reflection spectrum to the carbonaceopus meteor- son and three CM2 meteorites recovered from the Ant- ites dominating the outer-half of the main belt. In the arctic. The projectiles in these experiments were 1/8 th outer-half of the main belt about one-half of the carbo- inch diameter aluminum spheres fired at the meteorite naceous asteroids are hydrous, based on their infrared targets at speeds comparable to the collision velocities spectra [1]. The asteroids in the inner-half of the main in the main-belt. belt are predominantly anhydrous. Thus, about one- Each meteorite target was surrounded by “passive quarter of the main belt asteroids are hydrous. detectors” that included three thicknesses of aluminum Because dust particles from the main-belt asteroids foil to monitor the size of the small debris from the generally encounter the Earth with lower relative ve- distrption. The foil hole diameters were measured, and locities than dust from comets [2], asteroidal dust ex- converted to impacting particle diameters using the periences much less severe atmospheric entry heating calibration data of Hörz et al.
    [Show full text]
  • Liquid Water on Mars
    Report, Planetary Sciences Unit (AST80015), Swinburne Astronomy Online Preprint typeset using LATEX style emulateapj v. 12/16/11 LIQUID WATER ON MARS M. Usatov1 Report, Planetary Sciences Unit (AST80015), Swinburne Astronomy Online ABSTRACT Geomorphological, mineralogical and other evidence of the conditions favoring the existence of water on Mars in liquid phase is reviewed. This includes signatures of past and, possibly, present aqueous environments, such as the northern ocean, lacustrine environments, sedimentary and thermokarst landforms, glacial activity and water erosion features. Reviewed also are hydrous weathering processes, observed on surface remotely and also via analysis of Martian meteorites. Chemistry of Martian water is discussed: the triple point, salts and brines, as well as undercooled liquid interfacial and solid-state greenhouse effect melted waters that may still be present on Mars. Current understanding of the evolution of Martian hydrosphere over geological timescales is presented from early period to the present time, along with the discussion of alternative interpretations and possibilities of dry and wet Mars extremes. 1. INTRODUCTION morphological and mineralogical evidence of aqueous en- The presence of water on Earth, as seen from space, vironments available in the past and, possibly, present can be implied from the observations of low-albedo fea- time is presented in x3 which will be correlated with the tures, like seas and oceans, fluvial features on its sur- current understanding of the evolution of Martian hy- face, atmospheric phenomena, polar ice caps, and the drosphere at x4. Alternative (dry) interpretations of the snow cover exhibiting seasonal variations, not to mention evidence are discussed in x5. spectroscopy.
    [Show full text]
  • The Planet Earth-I)
    Geology (The Planet Earth-I) UNIT-1 The Planet Earth-I 1. ORIGIN OF THE SOLAR SYSTEM AND EARTH The Solar System The Solar System is made up of all the planets that orbit our Sun. In addition to planets, the Solar System also consists of moons, comets, asteroids, minor planets, and dust and gas. Everything in the Solar System orbits or revolves around the Sun. The Sun contains around 98% of all the material in the Solar System. The larger an object is, the more gravity it has. Because the Sun is so large, its powerful gravity attracts all the other objects in the Solar System towards it. At the same time, these objects, which are moving very rapidly, try to fly away from the Sun, outward into the emptiness of outer space. The result of the planets trying to fly away, at the same time that the Sun is trying to pull them inward is that they become trapped half-way in between. Balanced between flying towards the Sun, and escaping into space, they spend eternity orbiting around their parent star. Our solar system consists of an average star we call the Sun, the planets Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. It includes: the satellites of the planets; numerous comets, asteroids, and meteoroids; and the interplanetary medium. The Sun is the richest source of electromagnetic energy (mostly in the form of heat and light) in the solar system. The Sun's nearest known stellar neighbor is a red dwarf star called Proxima Centaury, at a distance of 4.3 light years away.
    [Show full text]
  • "THE GENERAL THEORY of META-DYNAMICS SYSTEMICITY" Part Four: Early Earth and Origin of Life’S Metadynamics Systemicity
    "THE GENERAL THEORY OF META-DYNAMICS SYSTEMICITY" Part four: Early Earth and origin of Life’s metadynamics systemicity Jean-Jacques BLANC Consulting Engineer Crets de Champel, 9 CH - 1206 – Geneva, Switzerland Tel/fax: +41(22)346 30 48 E-mail: [email protected] Url: www.bioethismscience.org The "Cosmo-planetary and terrestrial meta-dynamics systemicity”, the “Life’s meta-dynamics systemicity”, and "Biological meta-dynamics systemicity" are the core of a general theory resulting from a “Bioethism transdisciplinary approach” of the whole set of dynamics that made and sustains Life as to exist throughout the atomic and molecular universal cycles systemicity. Part four of this theory describes the Universe Cosmo-planetary metadynamics as having participated in the Sun system and its planets to form, particularly the Earth at the right “habitable zone”. The physicochemical environmental conditions of this site became propitious for Life to “hatch” within biochemical thermodynamics1 and evolution development metadynamics. ABSTRACT Ever since 1996, J.-J. Blanc, the author of this theory, made an extensive research on "Systems science" that induced to his developing a new systemic2 paradigm in terms of a transdisciplinary approach to "Living systems" that he named “The Bioethism” (see note 3). The transdisciplinary approach is meant to support the acquisition of a large understanding of living systems' origin, of their natural structure and their adaptive behaviors. Their specific bonds and traits, as well as their evolution trends, while permanently interacting with environmental events for survival4, require actions-reactions from ago-antagonistic signals and stimuli. Endogenous within their body milieu and exogenous, these signals and stimuli are adapting with conditions of ecosystemic and sociosystemic environments.
    [Show full text]
  • Proceedings of the Symposium on the Study of the Sun and Interplanetary Medium in Three Dimensions
    PROCEEDINGS OF THE SYMPOSIUM ON THE STUDY OF THE SUN AND INTERPLANETARY MEDIUM IN THREE DIMENSIONS (NASA-Tn-X-71397) FFCCE?EINGS OF THE 376-24119 SYRFOSIOF CK THE STUCY CF THE SUN ANC THRU INTPRPLBNETAFY EELIO?I IN THREE DIREMSIONS K76-24135 (NlSA) 345 F HC SJC.Cr3 SSCL 03E Unclas G3/92 2746b MARW 1976 -. , -GODDARD SPACE FLIGHT CENTER GREENBELT, MARYLAND PROCEEDINGS of the SYMPOSIUM ON THE STUDY OF THE SL.3 AND INTERPLANETARY FIEDIUY IN THREE DIbENSIONS held at GODDAP! SPACE FLIGHT CENTER under the sponsorship of HASA ESA AMERICAN ASTRONOMICAL SOCIETY AFIERICAN GEOPHYSICAL UNION The proceedinqs were edited by L. A. FISK PI. I. AXFORD Laboratory for Nigh Energy Astrophysics Max-Planck Institute for Aeronorq Goddard Space Flight Center Katlenhurg-Lindau, Germany Greenbelt, Maryland PREFACE On May 15-16, 1975, a symposium was held at the Goddard Space Flight Center on the Study of the Sun and Interplanetary Medium in Three Dimensions. The symposium brought together more than 200 scientists from the U. S. and Europe to discuss the importance of exploring the inter- planetary medium, and viewing the Sun over a wide range of heliographic latitudes. Among the topics discussed were the missions that NASA and ESA are currently considering for possible flight out of the ecliptic plane, and the likely scientific returns of these missions in the areas of solar, interplanetary and cosmic-ray physics. The symposium was sponsored by NASA and ESA, and was a topical meeting of the American Astronomical Society and the American Geophysical Union. In this proceedings an attempt has been made to pro- vide a complete summary of the content of the symposium.
    [Show full text]
  • Climatic Processes and Agriculture B
    UDC 551.12:620.96 © 2015 Climatic processes and agriculture B. Panasiuk, Academician of the NAAS, Doctor of Economic Sciences Institute of Bioenergetic Crops and Sugar Beet of the NAAS The purpose. To study and justify dependence of agriculture on new climatic processes on an instance of separate components, in particular dynamics of soil moisture and saturation with carbon dioxide (СО2). Methods. Analytical, statistical, generalizing philosophical-scientific understanding of nature of wildlife and climate; dependence of photosynthesis on natural instability of climatic processes, humanitarian-scientific understanding of sunspace energy. Results. It is proved that in modern conditions, together with rainfall and temperature of air, growth of cultivated plants is considerably depends on carbon dioxide (СО2) and soil moisture. Conclusions. To determine perspectives of further development of agriculture it is necessary to use in an index of hydrothermal quotient (HTQ) parameters of long-term daily average rainfall and temperatures of air, parameters of humidity of soils and level of concentration of carbon dioxide (СО2) which are expedient for fixing in the certain terrain. Key words: photosynthesis, soil moisture, carbon dioxide (СО2), rainfall, temperature of air, hydrothermal quotient, crops. Modern geological science claims that plants as representatives of living matter first appeared in the water, forming oxygen and the ozone layer. Subsequently, on the land began to form a modern plant and animal world, this process continues to this day. Often the question arises: Is it really that, having originated 3.8 billion years ago in the form of the simplest unicellular bacteria, has life been formed for so long from simple to complex? After all, on the planet Earth complicated, sometimes terrible geological processes occurred, the planet changed from one orbit to another, the climate changed many times.
    [Show full text]
  • Particles and Fields in the Interplanetary Medium M
    PARTICLES AND FIELDS IN THE INTERPLANETARY MEDIUM By KENNETH G. -MCCRACKEN UNIVERSITY OF ADELAIDE, ADELAIDE, AUSTRALIA M\Ian's knowledge of the properties of interplanetary space has advanced radically since 1962, the major part of this advance occurring since the commencement of the International Years of the Quiet Sun. The IQSY has, in fact, been quite unique in that it has seen the augmentation of the extensive synoptic studies of both geo- physical and solar phenomena such as were mounted during the IGY and its predecessors, the Polar Years of 1882 and 1932, by essentially continuous in situ studies of the interplanetary medium by detectors flown on interplanetary space- craft. Thus, since late 1963, no less than ten interplanetary spacecraft belonging to the Interplanetary -Monitoring Platform (DIP), Eccentric Geophysical Observa- tory (EGO), -Mariner, Pioneer, and Zond series have provided almost continuous surveillance of interplanetary phenomena, using second- and third-genleration detection devices. The fact that most of these spacecraft have made simultaneous measurements of a nIumber of the properties of the interplanetary medium has provided detailed information on the causal relationships between the several interplanetary parameters and geophysical phenomena, at a tinme when the relative lack of solar activity resulted in an attractive simplicity in the observed data. As' a consequence, the IQSY has provided an unprecedented series of observations of the causal relationships between solar, interplanetary, and geophysical phenomena, which will be of major importance in understanding the more complicated situations observed during periods of appreciable solar activity. In this review, I attempt to summarize the 1967 understanding of the interplanetary medium, this under- standing being based very heavily on work performed during and since the IQSY.
    [Show full text]
  • The Population of Starting Materials Available for Solar System Construction
    Messenger et al.: Population of Starting Materials for Solar System Construction 187 The Population of Starting Materials Available for Solar System Construction S. Messenger NASA Johnson Space Center S. Sandford NASA Ames Research Center D. Brownlee University of Washington Combined information from observations of interstellar clouds and star-forming regions and studies of primitive solar system materials give a first-order picture of the starting materials for the solar system’s construction. At the earliest stages, the presolar dust cloud was com- prised of stardust, refractory organic matter, ices, and simple gas phase molecules. The nature of the starting materials changed dramatically together with the evolving solar system. Increasing temperatures and densities in the disk drove molecular evolution to increasingly complex or- ganic matter. High-temperature processes in the inner nebula erased most traces of presolar materials, and some fraction of this material is likely to have been transported to the outer- most, quiescent portions of the disk. Interplanetary dust particles thought to be samples of Kuiper belt objects probably contain the least-altered materials, but also contain significant amounts of solar system materials processed at high temperatures. These processed materials may have been transported from the inner, warmer portions of the disk early in the active accretion phase. 1. INTRODUCTION rials from which the solar system formed and we review these constraints here. A central theme of this review is that A principal constraint on the formation of the solar sys- the nature of the starting materials evolved prior to and tem was the population of starting materials available for together with the nascent solar system and varied with loca- its construction.
    [Show full text]