DOCSLIB.ORG

Rumba, Salsa, Smaba and Tango in the Magnetosphere

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Rumba, Salsa, Smaba and Tango in the Magnetosphere ESCOUBET 24-08-2001 13:29 Page 2 r bulletin 107 — august 2001 42 ESCOUBET 24-08-2001 13:29 Page 3 the cluster quartet’s first year in space Rumba, Salsa, Samba and Tango in the Magnetosphere - The Cluster Quartet’s First Year in Space C.P. Escoubet & M. Fehringer Solar System Division, Space Science Department, ESA Directorate of Scientific Programmes, Noordwijk, The Netherlands P. Bond Cranleigh, Surrey, United Kingdom Introduction Launch and commissioning phase Cluster is one of the two missions – the other When the first Soyuz blasted off from the being the Solar and Heliospheric Observatory Baikonur Cosmodrome on 16 July 2000, we (SOHO) – constituting the Solar Terrestrial knew that Cluster was well on the way to Science Programme (STSP), the first recovery from the previous launch setback. ‘Cornerstone’ of ESA’s Horizon 2000 However, it was not until the second launch on Programme. The Cluster mission was first 9 August 2000 and the proper injection of the proposed in November 1982 in response to an second pair of spacecraft into orbit that we ESA Call for Proposals for the next series of knew that the Cluster mission was truly back scientific missions. on track (Fig. 1). In fact, the experimenters said that they knew they had an ideal mission only The four Cluster spacecraft were successfully launched in pairs by after switching on their last instruments on the two Russian Soyuz rockets on 16 July and 9 August 2000. On 14 fourth spacecraft. August, the second pair joined the first pair in highly eccentric polar orbits, with an apogee of 19.6 Earth radii and a perigee of 4 Earth radii. After the two launches, a quite lengthy The very accurate orbital injection and low fuel consumption mean verification phase for all spacecraft subsystems that spacecraft operations could continue for at least two more years and the payload of 44 instruments (Table 1) after the nominal two-year mission. started. The 16 solid booms, eight for the magnetometers and eight for communications, This is the first time that the Earth’s magnetic field and its environment were successfully deployed. A few days later, have been explored by a small constellation of four identical the spacecraft had to survive the first long spacecraft. Preliminary results show that, as predicted, with four eclipses, with up to 4 h of darkness, which they spacecraft we can obtain a detailed three-dimensional view of the did with very good performances from the Sun-Earth connection processes taking place at the interface onboard batteries. between the solar wind and the Earth’s magnetic field. Then started the verification phase for the 11 sets of instruments. This phase was After the Ariane-5 launcher failure on 4 June complicated by the fact that, to perform their 1996 and the destruction of the four original measurements, some instruments had to Cluster spacecraft, the Cluster scientists deploy very long wire antennas. These 44 m convinced the ESA Science Programme antennas altered the spin rate of the Committee (SPC) that it was essential for the spacecraft, which was incompatible with the European scientific community to rebuild the particle instruments that needed a fixed spin mission. This was agreed by the SPC in April rate. Altogether, more than 1100 individual 1997. In the meantime, SOHO, launched in tasks were performed on the instruments. December 1995, had begun to make some At the end of this phase, in early December, very exciting discoveries about the Sun and its a two-week ‘interference campaign’ was environment. Now, with the successful launch conducted to test how much the instruments of the rebuilt Cluster satellites, the STSP influenced each other. After successfully testing Cornerstone is complete and it is possible to all the instruments, the nominal operations combine these two missions in order to study phase began on 1 February 2001. Some of the the full chain of processes from the Sun’s results that are presented below were obtained interior to the Earth. during the commissioning and verification phase. 43 ESCOUBET 24-08-2001 13:29 Page 4 r bulletin 107 — august 2001 SC4 and SC1 separation 9 August 2000 16 July 2000 magnetopause and the polar cusp. In addition, unique data were obtained during a strong Figure 1. The two launches The Earth’s magnetosphere is a very large solar storm that occurred in November 2000. of the Cluster spacecraft on volume of space extending about 65 000 km in two Soyuz-Fregat rockets, the Sun’s direction, and more than two million km The bow shock on 16 July and 9 August in the opposite direction. The Earth’s magnetic The bow shock is the surface that forms in front 2000. An onboard camera took 27 pictures when field dominates this space. Without the of the Earth’s magnetosphere when the Rumba-SC1 separated from continuous flow of plasma (electrically charged supersonic solar wind slams into it at a speed Tango-SC4. Tango is shown particles) from the Sun, the Earth’s magnetic of about 400 km/s (around 1.5 million km/h). in the upper-right corner. field would be a dipole with a symmetric This is similar to the shock wave (or sonic The Earth can be seen in magnetic field around the polar axis. Instead, boom) when a plane flies faster than the speed the background the solar wind compresses the magnetosphere of sound in the atmosphere. The bow shock on the front side and shapes it into a long tail in slows down the solar wind and deflects it the anti-sunward direction (Fig. 2). During the around the magnetosphere. In the process, the first months of operations, the spacecraft orbits particles – electron and ions – are heated and allowed Cluster to visit key regions of the the strength of the magnetic field is increased. magnetosphere – the bow shock, the Intense electromagnetic waves are also produced at the shock. Table 1. The 11 instruments on each of the four Cluster spacecraft Figure 3 shows the electric waves detected by the WHISPER instrument during two crossings Instrument Principal Investigator of the bow shock by the four Cluster ASPOC (Spacecraft potential control) K. Torkar (IWF, A) spacecraft. On the plot, which covers a period of 40 minutes, the wave frequency is shown as CIS (Ion composition) H. Rème (CESR, F) a function of time. The power of the waves is EDI (Plasma drift velocity) G. Paschmann (MPE, D) plotted in false colours: red/brown for the most FGM (Magnetometer) A. Balogh (IC, UK) intense and blue for the less intense. PEACE (Electrons) A. Fazakerley (MSSL, UK) The bow shock is characterised by an intense RAPID (High-energy electrons and ions) P. Daly (MPAe, D) wave-emission enhancement below 20 kHz that is observed around 08:25 and 08:35 UT. DWP * (Wave processor) H. Alleyne (Sheffield, UK) The crossings do not occur at the same time EFW * (Electric field and waves) M. André (IRFU, S) for all spacecraft due to their different positions, which were about 600 km from each other at STAFF * (Magnetic and electric fluctuations) N. Cornilleau (CETP, F) that time. The right panel of Figure 3 shows the WBD * (Electric field and wave forms) D. Gurnett (IOWA, USA) spacecraft configuration at the first crossing, WHISPER * (Electron density and waves) P. Décréau (LPCE, F) when they were located on the right flank of the bow shock. A closer view of the spacecraft * Wave Experiment Consortium (WEC) configuration is shown in the middle-right and bottom-right panels. 44 ESCOUBET 24-08-2001 13:30 Page 5 the cluster quartet’s first year in space Figure 2. The Cluster orbit and the regions crossed during the first phase of the mission Figure 3. Bow-shock crossings by each of the four Cluster spacecraft on 22 December 2000. The left panels show the frequency/time spectrograms of the electric waves observed by the WHISPER instrument. Between about 08:25 and 08:35 UT, the spacecraft were in the solar wind. The diagrams on the right show the Cluster configuration during the bow-shock crossing, in an overall view (upper panel) and two enlarged views at 08:23 UT (middle panel) and 08:27 UT (bottom panel). The spacecraft and their trajectories are colour-coded: spacecraft 1 (Rumba-SC1) is shown in black, Salsa-SC2 in red, Samba-SC3 in green, and Tango-SC4 in magenta. Data courtesy of WHISPER Principal Investigator, P. Décréau (LPCE, France) Fp (kHz) 50 20 50 20 60 50 20 40 50 20 20 Signal level (dB0) ) 80 -3 Solar wind 40 0 Ne (cm Magnetosheath 08:05 08:15 08:25 08:35 08:45 Universal Time (HH:MM) 45 ESCOUBET 24-08-2001 13:30 Page 6 r bulletin 107 — august 2001 Since the bow shock usually moves faster than properties on quite short spatial scales, the spacecraft, the latter can be considered typically less than 600 km. Further studies will immobile with the bow shock is moving be conducted to understand the small-scale through the group. This motion is due to an structures of the bow shock. increase in the pressure of the solar wind (acting like a piston) on the magnetosphere, Figure 4 is another example of a bow-shock which pushes the bow shock closer to the crossing. Here the magnitude of the magnetic Earth. It is clear from the figure that spacecraft field is plotted as a function of time for the four 2 crossed the bow shock first, and then the spacecraft. In the supersonic solar wind other spacecraft followed. A few minutes later, (upstream of the bow shock), the magnetic field around 08:35 UT, the pressure decreased again is low, around 10 nT in this example, and and the bow shock crossed the spacecraft in high in the decelerated solar wind or the opposite direction.
Load more

Recommended publications
  • Estimating Random Transverse Velocities in the Fast Solar Wind from EISCAT Interplanetary Scintillation Measurements
    c Annales Geophysicae (2002) 20: 1265–1277 European Geophysical Society 2002 Annales Geophysicae Estimating random transverse velocities in the fast solar wind from EISCAT Interplanetary Scintillation measurements A. Canals1, A. R. Breen1, L. Ofman2, P. J. Moran1, and R. A. Fallows1 1Physics Department, University of Wales, Aberystwyth, Wales, UK 2The Catholic University of America and NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA Received: 17 October 2001 – Revised: 21 February 2002 – Accepted: 13 March 2002 Abstract. Interplanetary scintillation measurements can process of constructive and destructive interference change yield estimates of a large number of solar wind parameters, these phase variations into amplitude variations. As the ir- including bulk flow speed, variation in bulk velocity along regularities move out in the solar wind, the effect is to cast a the observing path through the solar wind and random varia- drifting diffraction pattern across the Earth. If the pattern is tion in transverse velocity. This last parameter is of particular sampled using two radio telescopes when the ray paths from interest, as it can indicate the flux of low-frequency Alfven´ the radio source to the antenna lie in the same radial plane – waves, and the dissipation of these waves has been proposed a plane passing through the center of the Sun – then a high as an acceleration mechanism for the fast solar wind. Anal- degree of correlation is present between the scintillation at ysis of IPS data is, however, a significantly unresolved prob- the two sites. The time lag for maximum correlation pro- lem and a variety of a priori assumptions must be made in in- vides a direct estimation of the scintillation drift velocity.
    [Show full text]
  • Radio Scintillation Observations of the Solar Wind - Recent Results from Eiscat and Proposals for a New-Generation System
    RADIO SCINTILLATION OBSERVATIONS OF THE SOLAR WIND - RECENT RESULTS FROM EISCAT AND PROPOSALS FOR A NEW-GENERATION SYSTEM A.R. Breen(1), G. Woan(2) (1)University of Wales Aberystwyth, Ceredigion SY23 3BZ, Wales, Email: [email protected] (2)University of Glasgow, Glasgow G12 8QQ, Scotland, Email: [email protected] ABSTRACT the spectral shape measured by a single antenna [2, 3] Measurements of radio scintillation which use the or – with greater accuracy, from the form of the cross- motion of ~100 km scale size density irregularities as spectra of the scintillation patterns measured at two flow tracers for solar wind speed (the technique of widely-separated sites at a time when the raypaths from Interplanetary Scintillation or IPS) have been used to source to antennas lie in a plane radial to the Sun [4, 5]. study the solar wind for many years. Recently Single antenna systems can make many more improvements to analysis methods have transformed observations but velocities derived from multi-site the capabilities of this technique and it has emerged as systems allow more accurate estimates of velocity [6]. a powerful tool for probing regions of the solar wind IPS measurements contain contributions from the which are hard to study by other means - particularly whole of the extended ray-path through the solar the region from ~25 solar radii (R) out to ~100 R. As atmosphere from the distant source to the receiving this is the region in which interaction between streams antenna(s). In earlier studies the inability to distinguish of solar wind and between mass ejections and the between contributions from different regions of the background wind determine the solar wind structure solar wind led to a "blurred" view of solar wind seen at Earth orbit good measurements of this region structure.
    [Show full text]
  • Survey of Conditions for Artificial Aurora Experiments at EISCAT
    Tsuda et al. Earth, Planets and Space (2018) 70:40 https://doi.org/10.1186/s40623-018-0805-9 TECHNICAL REPORT Open Access Survey of conditions for artifcial aurora experiments at EISCAT Tromsø using dynasonde data T. T. Tsuda1* , M. T. Rietveld2,3, M. J. Kosch4,5,6, S. Oyama7,8, K. Hosokawa1, S. Nozawa7, T. Kawabata7, A. Mizuno7 and Y. Ogawa8,9 Abstract We report a brief survey on conditions for artifcial aurora optical experiments in F region heating with O-mode at the EISCAT Tromsø site using dynasonde data from 2000 to 2017. The results obtained in our survey indicate the follow- ing: The possible conditions for conducting artifcial aurora experiments are concentrated in twilight hours in both evening and morning, compared with late-night hours; the possible conditions appear in fall, winter, and spring, while there is no chance in summer, and the month-to-month variation among fall, winter, and spring is not clear. The year- to-year variation is well correlated with the solar cycle, and experiments during the solar minimum would be almost hopeless. These fndings are useful for planning future artifcial aurora optical experiments. Keywords: Artifcial aurora, Ionospheric heating, EISCAT, Tromsø, Dynasonde Background heating experiments with O-mode polarization during Many researchers have been working on ionospheric nighttime to detect optical emissions in artifcial auro- heating experiments using high frequency (HF) radio ras (e.g., Gustavsson et al. 2005; Bryers et al. 2013; Kosch waves to understand phenomenon such as the interac- et al. 2014a, b; Blagoveshchenskaya et al. 2014). Tese tion processes between radio waves and plasma particles, published papers are obviously based on successful heat- which is an essential part of plasma physics.
    [Show full text]
  • Observations of Polar Cap Patch Substructures by EISCAT Svalbard Radar
    UNIVERSITY OF OSLO Department of Physics Observations of Polar Cap Patch Substructures by EISCAT Svalbard Radar Master Thesis Karina E. Bravo Ibáñez 1 May 2009 2 Preface The University in Oslo (UiO) gave me the opportunity to start a master in Space Physics. I am glad to have met many people related to space studies. I had the opportunity to take courses at the University centre in Svalbard (UNIS). Apart from the interesting theory background in space physics gained there, it was a great experience to live near the North Pole, and I will always have in mind the white mountains, the 24 hrs with darkness/sunlight, the exciting trips to the observatory stations, and of course the astonishing northern lights. I also had the chance to attend the International Space University Summer School Program (ISU SSP 2009) held in Barcelona thanks to the Norwegian Space Centre and, of course, to Ellen Osmundsen, Yvonne Rinne, Jøran Moen and Hans Pécseli for helping me with the application. I would like to thank my supervisors Jøran Moen and Kjellmar Oksavik for their help and guidance during this thesis, for their many interesting ideas on the subject and for always being available no matter the distance. I also thank Bjørn Lybekk and Espen Trondsen for technical assistance. I acknowledge the use of EISCAT data provided by the database in Kiruna, the use of ACE data provided by the ACE MAG and SWEPAM instruments teams, also the use of SuperDARN data provided by the John Hopkins University Applied Physics Laboratory. Thanks to Todd Pedersen who provided the scintillation data.
    [Show full text]
  • Astronomy & Astrophysics a Hipparcos Study of the Hyades
    A&A 367, 111–147 (2001) Astronomy DOI: 10.1051/0004-6361:20000410 & c ESO 2001 Astrophysics A Hipparcos study of the Hyades open cluster Improved colour-absolute magnitude and Hertzsprung{Russell diagrams J. H. J. de Bruijne, R. Hoogerwerf, and P. T. de Zeeuw Sterrewacht Leiden, Postbus 9513, 2300 RA Leiden, The Netherlands Received 13 June 2000 / Accepted 24 November 2000 Abstract. Hipparcos parallaxes fix distances to individual stars in the Hyades cluster with an accuracy of ∼6per- cent. We use the Hipparcos proper motions, which have a larger relative precision than the trigonometric paral- laxes, to derive ∼3 times more precise distance estimates, by assuming that all members share the same space motion. An investigation of the available kinematic data confirms that the Hyades velocity field does not contain significant structure in the form of rotation and/or shear, but is fully consistent with a common space motion plus a (one-dimensional) internal velocity dispersion of ∼0.30 km s−1. The improved parallaxes as a set are statistically consistent with the Hipparcos parallaxes. The maximum expected systematic error in the proper motion-based parallaxes for stars in the outer regions of the cluster (i.e., beyond ∼2 tidal radii ∼20 pc) is ∼<0.30 mas. The new parallaxes confirm that the Hipparcos measurements are correlated on small angular scales, consistent with the limits specified in the Hipparcos Catalogue, though with significantly smaller “amplitudes” than claimed by Narayanan & Gould. We use the Tycho–2 long time-baseline astrometric catalogue to derive a set of independent proper motion-based parallaxes for the Hipparcos members.
    [Show full text]
  • Planned Yet Uncontrolled Re-Entries of the Cluster-Ii Spacecraft
    PLANNED YET UNCONTROLLED RE-ENTRIES OF THE CLUSTER-II SPACECRAFT Stijn Lemmens(1), Klaus Merz(1), Quirin Funke(1) , Benoit Bonvoisin(2), Stefan Löhle(3), Henrik Simon(1) (1) European Space Agency, Space Debris Office, Robert-Bosch-Straße 5, 64293 Darmstadt, Germany, Email:[email protected] (2) European Space Agency, Materials & Processes Section, Keplerlaan 1, 2201 AZ Noordwijk, Netherlands (3) Universität Stuttgart, Institut für Raumfahrtsysteme, Pfaffenwaldring 29, 70569 Stuttgart, Germany ABSTRACT investigate the physical connection between the Sun and Earth. Flying in a tetrahedral formation, the four After an in-depth mission analysis review the European spacecraft collect detailed data on small-scale changes Space Agency’s (ESA) four Cluster II spacecraft in near-Earth space and the interaction between the performed manoeuvres during 2015 aimed at ensuring a charged particles of the solar wind and Earth's re-entry for all of them between 2024 and 2027. This atmosphere. In order to explore the magnetosphere was done to contain any debris from the re-entry event Cluster II spacecraft occupy HEOs with initial near- to southern latitudes and hence minimise the risk for polar with orbital period of 57 hours at a perigee altitude people on ground, which was enabled by the relative of 19 000 km and apogee altitude of 119 000 km. The stability of the orbit under third body perturbations. four spacecraft have a cylindrical shape completed by Small differences in the highly eccentric orbits of the four long flagpole antennas. The diameter of the four spacecraft will lead to various different spacecraft is 2.9 m with a height of 1.3 m.
    [Show full text]
  • Estimates of Magnetotail Reconnection Rate Based on IMAGE FUV and EISCAT Measurements
    Annales Geophysicae (2005) 23: 123–134 SRef-ID: 1432-0576/ag/2005-23-123 Annales © European Geosciences Union 2005 Geophysicae Estimates of magnetotail reconnection rate based on IMAGE FUV and EISCAT measurements N. Østgaard1, J. Moen2,3, S. B. Mende1, H. U. Frey1, T. J. Immel1, P. Gallop4, K. Oksavik2, and M. Fujimoto5 1Space Sciences Laboratory, University of California, Berkeley, California, USA 2Department of Physics, University of Oslo, Norway 3University Centre on Svalbard, Longyearbyen, Norway 4Rutherford Appleton Laboratory, Oxfordshire, UK 5Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Japan Received: 16 September 2003 – Revised: 15 March 2004 – Accepted: 30 March 2004 – Published: 31 January 2005 Part of Special Issue “Eleventh International EISCAT Workshop” Abstract. Dayside merging between the interplanetary and additional lower frequencies, 0.5 and 0.8 mHz, that might be terrestrial magnetic fields couples the solar wind electric field modulated by solar wind pressure variations. to the Earth’s magnetosphere, increases the magnetospheric Key words. Magnetospheric physics (magnetotail; electric convection and results in efficient transport of solar wind en- fields; magnetosphere - ionosphere interaction; solar wind - ergy into the magnetosphere. Subsequent reconnection of the magnetosphere interaction). Space plasma physics (magnetic lobe magnetic field in the magnetotail transports energy into reconnection) the closed magnetic field region. Combining global imag- ing and ground-based radar measurements, we estimate the reconnection rate in the magnetotail during two days of an EISCAT campaign in November-December 2000. Global 1 Introduction images from the IMAGE FUV system guide us to identify ionospheric signatures of the open-closed field line bound- A fundamental element of the open magnetosphere model ary observed by the two EISCAT radars in Tromsø (VHF) first suggested by Dungey (1961) is that dayside merging and on Svalbard (ESR).
    [Show full text]
  • EISCAT Observation of Wave‐Like Fluctuations in Vertical Velocity Of
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Munin - Open Research Archive Journal of Geophysical Research: Space Physics RESEARCH ARTICLE EISCAT Observation of Wave-Like Fluctuations in Vertical 10.1029/2018JA025399 Velocity of Polar Mesospheric Summer Echoes Key Points: Associated With a Geomagnetic Disturbance • Vertical velocity of PMSE was observed to oscillate at near- Young-Sook Lee1 , Yong Ha Kim1 , Kyung-Chan Kim2 , Young-Sil Kwak3,4 , buoyancy period of mesosphere after 5 5 6 the onset of substorm Timothy Sergienko , Sheila Kirkwood , and Magnar G. Johnsen • Variation of PMSE intensity is well 1 2 correlated with that of E region Department of Astronomy and Space Science, Chungnam National University, Daejeon, South Korea, Division of Science electron density Education, College of Education, Daegu University, Gyeongsan, South Korea, 3Korea Astronomy and Space Science • Initial creation of PMSE is induced by Institute, Daejeon, South Korea, 4Department of Astronomy and Space Science, University of Science and Technology, both particle precipitation and air Daejeon, South Korea, 5Swedish Institute of Space Physics, Kiruna, Sweden, 6Tromsø Geophysical Observatory, UiT-The updraft that was observed as large upward velocity Arctic University of Norway, Tromsø, Norway Supporting Information: Abstract By analyzing a data set from the European Incoherent SCATter (EISCAT) Very High Frequency • Supporting Information S1 (VHF) radar at Tromsø, we find that both radar reflectivity and upward ion velocity in a polar mesospheric • Figure S1 summer echo (PMSE) layer simultaneously increased at the commencement of a local geomagnetic disturbance, which occurred at midnight on 9 July 2013. The onset of the upward velocity was followed by Correspondence to: Y.
    [Show full text]
  • Solar Wind Magnetic Field Components
    Characteristics of a HSS-driven magnetic storm in the high-latitude ionosphere N. Ellahouny, A. Aikio, M. Pedersen, H. Vanhamäki, I. Virtanen, J. Norberg, M. Grandin, Al.Kozlovsky, T. Raita, K. Kauristie, A. Marchaudon, P.-L. Blelly, S.-I. Oyama 1) Ionospheric Physics Research Unit, University of Oulu, Finland, 2) Finnish Meteorological Institute, Helsinki, 3) CoE in Sustainable Space, University of Helsinki 4) Sodankylä Geophysical Observatory, Finland, 5) IRAP, University of Tolouse, France,6) Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, Japan Email: [email protected] SS1 SS2 SS3 SS4 SS5 SS6 SS7 SS8 SS9 SS10 SS11 SS12 SS13 (a) 1. Introduction Solar wind high-speed streams (HSSs) >400 km/s that (b) emanate from Solar coronal holes have a significant impact on the geomagnetic activity during the declining phase of the solar cycle [Gonzalez et al., 1999; Tsurutani et al.,2006]. When HSSs catch up the preceding slow solar wind, they (c) create a compressed plasma region, called co-rotating interaction region (CIR). HSSs can induce geomagnetic storms that last for several days [Borovsky and Denton, (d) 2006] and affect the ionospheric behavior, specially at the high latitudes [Grandin et al., 2015; Marchaudon et al., 2018]. When a magnetospheric substorm takes place, (e) injection of electrons and protons occur. In this poster, we present one of the longest storms in the current solar cycle (24) that occurred on 14th of March 2016. (f) 2. Data and initial results 2.1 Solar wind driver Figure 2 Solar wind parameters and magnetic indices during (14-22 March 2016).
    [Show full text]
  • Observing and Analysing Structures in Active Aurora with the ASK Optical Instrument and EISCAT Radar
    Motivating talk on exciting work with EISCAT: Observing and analysing structures in active aurora with the ASK optical instrument and EISCAT radar. EISCAT Summer School part I - 31st July 2007 Hanna Dahlgren (KTH, Sweden) & Daniel Whiter (University of Southampton, UK) 1 (25) Auroral Spatial Scales Oval up to 1000 km Large-Scale Inverted-V 100 km Inverted-V Arc 10 km 100 km Filaments 1 km o v a l 1 arcs 5-20 km 0 0 0 k m DMSP auroralauroral rays rays Black auroral auroral fine- curls: 1 km widths structure < 1 km 2 (25) Ground-based observations of the fine-scale aurora Examples of discrete auroral structures 0.1 to 1 km wide T.Trondsen (Univ of Calgary) Few instruments can measure it well Few theoretical models can account for it 3 (25) Our Motivation • Optical data provides information on morphology of the aurora. • Simultaneous radar measurements give additional information on ionospheric properties. • We focus on the smallest structures seen, by using high-resolution imagers, equipped with different filters to measure specific emissions. - The EISCAT radars give us information on the condition of the ionosphere at the time, electric fields and flows. This is used in our modelling of the ionosphere. 4 (25) ASK Auroral Structure and Kinetics Instrument to study small scale structure of the aurora, at high temporal and spatial resolution. Three narrow FOV cameras for simultaneous imaging in three spectral bands: + - ASK1a: 5620 Å → O2 (E-region, high energy e ) - ASK1b: 6730 Å → N2 (E-region, high energy e ) ASK2a: 7320 Å → O+ (F-region,
    [Show full text]
  • Ariane 501 Incident at Three Levels of Description
    Launch Failures! December 1, 1994! Ariane 501 Incident " Ariane 4 ! 70th flight! at Three Levels of Description! February 19, 1996! Long March 3B ! 1st flight! 501 Report Dates! 501 Launch Events! June 4, 1996! 0 seconds! Ariane 501 ! June 4-6, 1996! H0 - main cryogenic ! 1st flight! Initial reports of the ! engine ignition! incident! 7 seconds! August 12, 1998! Liftoff! Titan 4A ! 36.7 seconds! Backup inertial reference ! 20th flight! June 6 - July 19, 1996! system inoperative due to ! Intermediate reports! numerical overflow in ! August 26, 1998! horizontal velocity! Delta 3 ! 37.2 seconds! Primary inertial reference ! 1st flight ! July 19, 1996! system inoperative due to ! Inquiry Board Report! numerical overflow in ! horizontal velocity! Time! (months)! 37-38 seconds! July 20-26, 1996! Booster and main engine ! Reports based on ! nozzles swivel, rocket veers ! off course and breaks up ! inquiry findings! from aerodynamic loads ! July 27 - September, 1996! 39 seconds! Automatic self-destruct ! Comprehensive reports ! 45 seconds! Time! Time! Range safety officer destruct ! (days)! (secs.)! “High Profit” Documents! Ariane 5 Flight 501 Failure: Report by the Inquiry Board (July 19, 1996)! Inertial Reference Software Error Blamed for Ariane 5 Failure; Defense !Daily (July 24, 1996) ! !!! Software Design Flaw Destroyed Ariane 5; next flight in 1997; ! !Aerospace Daily (July 24, 1996) ! !! Ariane 5 Rocket Faces More Delay; The Financial Times Limited ! !(July 24, 1996) ! Flying Blind: Inadequate Testing led to the Software Breakdown that !Doomed Ariane
    [Show full text]
  • European Space Agency Announces Contest to Name the Cluster Quartet
    European Space Agency Announces Contest to Name the Cluster Quartet. 1. Contest rules The European Space Agency (ESA) is launching a public competition to find the most suitable names for its four Cluster II space weather satellites. The quartet, which are currently known as flight models 5, 6, 7 and 8, are scheduled for launch from Baikonur Space Centre in Kazakhstan in June and July 2000. Professor Roger Bonnet, ESA Director of Science Programme, announced the competition for the first time to the European Delegations on the occasion of the Science Programme Committee (SPC) meeting held in Paris on 21-22 February 2000. The competition is open to people of all the ESA member states. Each entry should include a set of FOUR names (places, people, or things from his- tory, mythology, or fiction, but NOT living persons). Contestants should also describe in a few sentences why their chosen names would be appropriate for the four Cluster II satellites. The winners will be those which are considered most suitable and relevant for the Cluster II mission. The names must not have been used before on space missions by ESA, other space organizations or individual countries. One winning entry per country will be selected to go to the Finals of the competition. The prize for each national winner will be an invitation to attend the first Cluster II launch event in mid-June 2000 with their family (4 persons) in a 3-day trip (including excursions to tourist sites) to one of these ESA establishments: ESRIN (near Rome, Italy): winners from France, Ireland, United King- dom, Belgium.
    [Show full text]