DOCSLIB.ORG

Electromagnetic Compatibility (EMC) Evaluation of the SELENE Spacecraft for the Lunar Radar Sounder (LRS) Observations

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Electromagnetic Compatibility (EMC) Evaluation of the SELENE Spacecraft for the Lunar Radar Sounder (LRS) Observations Earth Planets Space, 60, 333–340, 2008 Electromagnetic compatibility (EMC) evaluation of the SELENE spacecraft for the lunar radar sounder (LRS) observations A. Kumamoto1,T.Ono1, Y. Kasahara2, Y. Goto2, Y. Iijima3, and S. Nakazawa4 1Graduate School of Science, Tohoku University, 6-3, Aoba, Aramaki, Aoba, Sendai 980-8578, Japan 2Graduate School of Natural Science and Technology, Kanazawa University, 2-40-20, Kakuma-machi, Kanazawa 920-1192, Japan 3Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1, Yoshinodai, Sagamihara 229-8510, Japan 4Tsukuba Space Center, Japan Aerospace Exploration Agency, 2-1-1, Sengen, Tsukuba 305-8505, Japan (Received March 16, 2007; Revised July 12, 2007; Accepted August 3, 2007; Online published April 9, 2008) In order to achieve the lunar subsurface sounding and planetary radio wave observations by the Lunar Radar Sounder (LRS) onboard the SELENE spacecraft, strict electromagnetic compatibility (EMC) requirements were applied for all instruments and the whole system of the spacecraft. In order to detect the lunar subsurface echoes from a depth of 5 km, the radiated emission (RE) limit was determined to be −10 dBμV/m and the common- mode (CM) current limit to be 20 dBμA. The EMC performance of the spacecraft was finally evaluated in the system EMC test held from Oct. 20 to Oct. 22, 2005. There is no broadband noise but some narrowband noises at a level above the CM-current limit in a frequency range from 4 to 6 MHz, in which radar soundings are operated. Based on the noise spectrum within 4–6 MHz, the noise level of FMCW radar sounder is estimated to be 14 dB lower than the CM-current limit. In the SELENE EMC test, the following new techniques were introduced: (1) systematic control and evaluation of CM-current noises were first performed to improve the spacecraft EMC performance; (2) onboard battery operation was utilized for reduction of ambient broadband noises during EMC measurements. Key words: SELENE spacecraft, lunar radar sounder (LRS), subsurface radar sounding, electromagnetic com- patibility (EMC), radiated emission (RE) noise, common-mode current noise. 1. Introduction while LRS-A2/P2 (Y1 antenna) and LRS-A3/P3 (X2 an- Global survey of the lunar subsurface structure by the tenna) are near the +Y panel. The antenna elements are lunar radar sounder (LRS) is one of the most challenging fully retracted when the spacecraft is launched. After the objectives of the SELENE mission (Ono and Oya, 2000; spacecraft is injected into the lunar orbit, the antenna ele- Ono et al., 2008). In order to detect weak lunar subsur- ments are extended up to a length of 15 m and used for car- face echoes and to perform advanced analyses (Kobayashi rying out lunar subsurface radar soundings in a frequency et al., 2002a, b; Kobayashi and Ono, 2006, 2007), the artifi- range of 4 to 6 MHz and making observations of natural ra- cial noises originating from the SELENE spacecraft system dio and plasma waves in a frequency range up to 30 MHz. itself should be suppressed adequately below the estimated The artificial noises that affect the observations for sci- subsurface echo level. Not only radar soundings of the lunar entific purposes are categorized into two groups: radiated subsurface structure but also observations of planetary radio emission (RE) noises and conducted emission (CE) noises. waves, such as Jovian hectometric (HOM) and decametric RE noises appear as an unfavorable electric field emitted (DAM) emissions, and plasma waves around the moon are from the components and cables onboard the spacecraft. CE planned using the LRS high sensitive receiver. noises take the form of an unfavorable current which dis- The instrumentation of the LRS has been described in de- turbs other instruments via the interconnecting cables. Es- tail by Ono and Oya (2000) and Ono et al. (2008). The LRS pecially in the case of the spacecraft, common-mode (CM) consists of four antenna units (LRS-A1, A2, A3, and A4), currents passing through the spacecraft panels cause EMC four preamplifier units (LRS-P1, P2, P3, and P4), and the problems. Most spacecraft BUS equipments and scientific main electric circuit unit (LRS-E). An overview of the SE- instruments consist of separated components. For example, LENE spacecraft is shown in Fig. 1. Antenna units and cor- the lunar magnetic field and particle plasma (MAP) instru- responding preamplifier units are set together in four brack- ment consists of magnetometer, mast deployment equip- ets and installed on the inner side of the +Z panel, which ment, four particle detectors, and the main electric circuit is always oriented to the moon center. LRS-A1/P1 (X1 an- unit installed on the different spacecraft panels. The com- tenna) and LRS-A4/P4 (Y2 antenna) are near the −Y panel, ponents are connected with cables, or several sets of HOT and RTN lines. When the HOT and RTN currents in the Copyright c The Society of Geomagnetism and Earth, Planetary and Space Sci- cables are balanced each other, there is no current and no ences (SGEPSS); The Seismological Society of Japan; The Volcanological Society potential difference between the spacecraft panels. In prac- of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sci- ences; TERRAPUB. tice, however, the HOT and RTN currents are not balanced 333 334 A. KUMAMOTO et al.: SELENE EMC EVALUATION FOR LUNAR RADAR SOUNDING Fig. 1. Overview of the locations of the spacecraft panels and LRS antenna elements. The Z axis is directed toward the moon center; the X axis is aligned with the orbit. and impedance between the spacecraft panels is not 0 in gent tan δ = Im ε/Re ε, the ratio of real and imaginary parts whole frequency range up to 30 MHz. CM currents appear of permittivity is smaller than 0.006. Based on recent ob- in the spacecraft panels and produce the potential difference servations of galactic background radiations in HF ranges between the LRS preamplifier inputs. The CM currents in (Dulk et al., 2001; Manning and Dulk, 2001; Zarka et al., the spacecraft panels can be evaluated by making measure- 2004), the flux density of galactic back ground radiation is ments of unbalanced currents in the interconnecting cables S =−190 dBW/m2Hz at 5 MHz. If we consider that the between the instrument components. effective length of the LRS dipole antenna is Le = λ/π = In order to suppress the artificial noises mentioned above, 19.1 m, free space impedance is Z0 = 120π , and receiv- strict EMC requirements were applied for all components ing bandwidth of LRS is 3 kHz, the electric field of galactic and the whole system of the SELENE spacecraft. The tech- noise and the voltage produced at the LRS preamplifier in- niques for EMC control and EMC evaluation of the space- put are obtained as follows: craft with scientific payloads have been improved through = = . μ the trials made for the Akebono (Kimura et al., 1990; Oya E SZ0 f 0 336 V/m (1) et al., 1990), Geotail (Tsutsui et al., 1992; Matsumoto et = = . μ al., 1994), and Nozomi (Ono et al., 1998; Matsumoto et V ELe 6 42 V (2) al., 1998) missions, and the methodology of the SELENE Therefore, echoes with electric field intensity larger than EMC control is based on them. It is especially based on −10 dBμV/m, which produce a voltage larger than the EMC investigation of the Nozomi power supply unit, 16 dBμV at the LRS preamplifier input, have to be de- where it was recognized that the EMC performance of the tectable by the LRS. Based on Zarka (1998) and Zarka et spacecraft is highly dependent on the CM-current noises in al. (2004), the intensity of Jovian HOM and DAM emis- the interconnecting cables between instruments. The total sions in active cases is estimated to be −190 dBW/m2Hz EMC performance of the SELENE spacecraft was finally at the lunar orbit. In order to avoid the lunar subsurface checked in the system EMC test held from October 20 to echo and the planetary radio waves from being masked by 22, 2005 in the anechoic chamber of the Tsukuba Space artificial RE noises, limit for RE noises (Fig. 2) was deter- Center (TKSC), Japan Aerospace and Exploration Agency mined. The RE limit for instruments outside the spacecraft (JAXA). In this paper, the results of SELENE EMC control panels is −10 dBμV/m in a frequency range from 14 kHz for the lunar subsurface radar sounding are presented in de- to 30 MHz, which is just equal to the galactic noise level tail. The basis of SELENE EMC standard and methodology at 5 MHz. As reported by the previous studies of galac- of EMC controls are described in Section 2. The results of tic noise spectrum (Dulk et al., 2001; Manning and Dulk, the final system EMC test are shown in Section 3, and the 2001; Zarka et al., 2004), the galactic noise level in a fre- discussion and conclusions are presented in Section 4. quency range below 1 MHz is lower than that at 5 MHz. The RE limit below 1 MHz was, however, determined to be 2. EMC Requirements for the SELENE Space- larger than −10 dBμV/m because the ambient noise level craft in the first EMC test in 2004 was as high as −10 dBμV/m. The galactic noise level is considered to be a criterion It was inferred that the external power supply of the space- for detection of the lunar the subsurface echo by the LRS. craft brought the external noises into the anechoic chamber Based on the feasibility study by Ono and Oya (2000), the in the first EMC test.
Load more

Recommended publications
  • Gravimetric Missions in Japanese Lunar Explorer, SELENE
    Gravimetric Missions in Japanese Lunar Explorer, SELENE H. Hanada1), T. Iwata2), N. Namiki3), N. Kawano1), K. Asari1), T. Ishikawa1), F. Kikuchi1), Q. Liu1), K. Matsumoto1), H. Noda1), J. Ping4), S. Tsuruta1), K. Iwadate1), O. Kameya1), S. Kuji1), Y. Tamura1), X. Hong4), Y. Aili5), S. Ellingsen6) 1) National Astronomical Observatory of Japan 2) Japan Aerospace Exploration Agency 3) Kyushu University 4) Shanghai Astronomical Observatory, Chinese Academy of Sciences 5)Urumqi Astronomical Observatory,Chinese Academy of Sciences 6) University of Tasmania ABSTRACT SELENE (SElenological and Engineering Explorer), is a mission in preparation for launch in 2007 by JAXA (Japan Aerospace Exploration Agency), it carries 15 missions, two of which (RSAT and VRAD) are gravimetric experiments using radio waves. The RSAT (Relay Satellite Transponder) mission will undertake 4-way Doppler measurements of the main orbiter through the Rstar sub-satellite. This is in addition to 2-way Doppler and ranging measurements of the satellites and will realize the first direct observation of the gravity fields on the far side of the Moon. The VRAD (Differential VLBI Radio Source) mission involves observing the trajectories of Rstar and Vstar using differential VLBI with both a Japanese network (VERA), and an international network. We have already finished development of the onboard instruments and are carrying out proto-flight tests under various conditions. We have also performed test VLBI observations of orbiters with the international network. 1. INTRODUCTION Although it is the nearest astronomical body to the Earth, there are many unsolved problems relating to the origin and the evolution of the Moon. Numerous lunar explorations have been made with the aim of elucidating these problems, however, we still know little of the deep interior of the Moon.
    [Show full text]
  • Chandrayaan-2 Completes a Year Around the Moon
    One-year completion of Chandrayaan-2 Lunar orbit insertion (August 20, 2019) Chandrayaan-2 completes a year around the Moon The Moon provides the best linkage to understand Earth’s early history and offers an undisturbed record of the inner Solar system environment. It could also be a base for future human space exploration of the solar system and a unique laboratory, unlike any on Earth, for fundamental physics investigations. In spite of several missions to the Moon, there remains several unanswered questions. Continued high resolution studies of its surface, sub-surface/interior and its low-density exosphere, are essential to address diversities in lunar surface composition and to trace back the origin and evolution of the Moon. The clear evidence from India’s first mission to the Moon, Chandrayaan-1, on the extensive presence of surface water and the indication for sub- surface polar water-ice deposits, argues for more focused studies on the extent of water on the surface, below the surface and in the tenuous lunar exosphere, to address the true origin and availability of water on Moon. With the goal of expanding the lunar scientific knowledge through detailed studies of topography, mineralogy, surface chemical composition, thermo-physical characteristics and the lunar exosphere, Chandrayaan-2 was launched on 22nd July 2019 and inserted into the lunar orbit on 20th August 2019, exactly one year ago. Though the soft-landing attempt was not successful, the orbiter, which was equipped with eight scientific instruments, was successfully placed in the lunar orbit. The orbiter completed more than 4400 orbits around the Moon and all the instruments are currently performing well.
    [Show full text]
  • Transmittal of Geotail Prelaunch Mission Operation Report
    National Aeronautics and Space Administration Washington, D.C. 20546 ss Reply to Attn of: TO: DISTRIBUTION FROM: S/Associate Administrator for Space Science and Applications SUBJECT: Transmittal of Geotail Prelaunch Mission Operation Report I am pleased to forward with this memorandum the Prelaunch Mission Operation Report for Geotail, a joint project of the Institute of Space and Astronautical Science (ISAS) of Japan and NASA to investigate the geomagnetic tail region of the magnetosphere. The satellite was designed and developed by ISAS and will carry two ISAS, two NASA, and three joint ISAS/NASA instruments. The launch, on a Delta II expendable launch vehicle (ELV), will take place no earlier than July 14, 1992, from Cape Canaveral Air Force Station. This launch is the first under NASA’s Medium ELV launch service contract with the McDonnell Douglas Corporation. Geotail is an element in the International Solar Terrestrial Physics (ISTP) Program. The overall goal of the ISTP Program is to employ simultaneous and closely coordinated remote observations of the sun and in situ observations both in the undisturbed heliosphere near Earth and in Earth’s magnetosphere to measure, model, and quantitatively assess the processes in the sun/Earth interaction chain. In the early phase of the Program, simultaneous measurements in the key regions of geospace from Geotail and the two U.S. satellites of the Global Geospace Science (GGS) Program, Wind and Polar, along with equatorial measurements, will be used to characterize global energy transfer. The current schedule includes, in addition to the July launch of Geotail, launches of Wind in August 1993 and Polar in May 1994.
    [Show full text]
  • Protons in the Near Lunar Wake Observed by the SARA Instrument on Board Chandrayaan-1
    FUTAANA ET AL. PROTONS IN DEEP WAKE NEAR MOON 1 Protons in the Near Lunar Wake Observed by the SARA 2 Instrument on Board Chandrayaan-1 3 Y. Futaana, 1 S. Barabash, 1 M. Wieser, 1 M. Holmström, 1 A. Bhardwaj, 2 M. B. Dhanya, 2 R. 4 Sridharan, 2 P. Wurz, 3 A. Schaufelberger, 3 K. Asamura 4 5 --- 6 Y. Futaana, Swedish Institute of Space Physics, Box 812, Kiruna, SE-98128, Sweden. 7 ([email protected]) 8 9 10 1 Swedish Institute of Space Physics, Box 812, Kiruna, SE-98128, Sweden 11 2 Space Physics Laboratory, Vikram Sarabhai Space Center, Trivandrum 695 022, India 12 3 Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland 13 4 Institute of Space and Astronautical Science, 3-1-1 Yoshinodai, Sagamihara, Japan 14 Index Terms 15 6250 Moon 16 5421 Interactions with particles and fields 17 2780 Magnetospheric Physics: Solar wind interactions with unmagnetized bodies 18 7807 Space Plasma Physics: Charged particle motion and acceleration 19 Abstract 20 Significant proton fluxes were detected in the near wake region of the Moon by an ion mass 21 spectrometer on board Chandrayaan-1. The energy of these nightside protons is slightly higher than 22 the energy of the solar wind protons. The protons are detected close to the lunar equatorial plane at 23 a 140˚ solar zenith angle, i.e., ~50˚ behind the terminator at a height of 100 km. The protons come 24 from just above the local horizon, and move along the magnetic field in the solar wind reference 25 frame.
    [Show full text]
  • Highlights in Space 2010
    International Astronautical Federation Committee on Space Research International Institute of Space Law 94 bis, Avenue de Suffren c/o CNES 94 bis, Avenue de Suffren UNITED NATIONS 75015 Paris, France 2 place Maurice Quentin 75015 Paris, France Tel: +33 1 45 67 42 60 Fax: +33 1 42 73 21 20 Tel. + 33 1 44 76 75 10 E-mail: : [email protected] E-mail: [email protected] Fax. + 33 1 44 76 74 37 URL: www.iislweb.com OFFICE FOR OUTER SPACE AFFAIRS URL: www.iafastro.com E-mail: [email protected] URL : http://cosparhq.cnes.fr Highlights in Space 2010 Prepared in cooperation with the International Astronautical Federation, the Committee on Space Research and the International Institute of Space Law The United Nations Office for Outer Space Affairs is responsible for promoting international cooperation in the peaceful uses of outer space and assisting developing countries in using space science and technology. United Nations Office for Outer Space Affairs P. O. Box 500, 1400 Vienna, Austria Tel: (+43-1) 26060-4950 Fax: (+43-1) 26060-5830 E-mail: [email protected] URL: www.unoosa.org United Nations publication Printed in Austria USD 15 Sales No. E.11.I.3 ISBN 978-92-1-101236-1 ST/SPACE/57 *1180239* V.11-80239—January 2011—775 UNITED NATIONS OFFICE FOR OUTER SPACE AFFAIRS UNITED NATIONS OFFICE AT VIENNA Highlights in Space 2010 Prepared in cooperation with the International Astronautical Federation, the Committee on Space Research and the International Institute of Space Law Progress in space science, technology and applications, international cooperation and space law UNITED NATIONS New York, 2011 UniTEd NationS PUblication Sales no.
    [Show full text]
  • FACTORS" with Multiple Compact Satellites for the Space-Earth Coupling Mechanisms
    PCG21-05 Japan Geoscience Union Meeting 2018 Science Objectives and Mission Plan of "FACTORS" with Multiple Compact Satellites for the Space-Earth Coupling Mechanisms *Masafumi Hirahara1, Yoshifumi Saito2, Hirotsugu Kojima3, Naritoshi Kitamura2, Kazushi Asamura 2, Ayako Matsuoka2, Takeshi Sakanoi4, Yoshizumi Miyoshi1, Shin-ichiro Oyama1, Masatoshi Yamauchi5, Yuichi Tsuda2, Nobutaka Bando2 1. Institute of Space-Earth Environmental Research, Nagoya University, 2. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3. Research Institute for Sustainable Humanosphere, Kyoto University, 4. Planetary Plasma and Atmospheric Research Center, Graduate School of Science, Tohoku University, 5. Swedish Institute of Space Physics After the successful launch and the recent observational progresses of the ERG(Arase) satellite mission, we have been leading the next community exploration mission in the Japanese space physics research. In the ERG mission, we are focusing on the unique space plasma mechanisms and conditions causing the terrestrial radiation belt through the wave-particle interaction analyses and the triangle-type research system consisting the satellite and ground-based observations and the data analyses/modelings/simulations. Our next exploration target is the space-Earth connection processes/mechanisms responsible for the formation and coupling of the terrestrial magnetosphere/ionoshere/thermosphere and the acceleration and transportation of the space plasma and neutral atmospheric particles, which could be
    [Show full text]
  • Geotail/CPI Publications
    Geotail/CPI Publications L. A. Frank, et al. Department of Physics and Astronomy The University of Iowa Iowa City, IA 1994 1. Frank, L. A., K. L. Ackerson, W. R. Paterson, J. A. Lee, M. R. English and G. L. Pickett, The Comprehensive Plasma Instrumentation (CPI) for the Geotail Spacecraft, J. Geomag. and Geoelectr., 46, 23-37, 1994. 2. Kokubun, S., H. Kawano, M. Nakamura, T. Yamamoto, K. Tsuruda, H. Hayakawa, A. Matsuoka and L. A. Frank, Quasi-periodic Oscillations of the Magnetopause During Northward Sheath Magnetic Field, Geophys. Res. Lett., 21. 2883-2886, 1994. 3. Kojima, H., H. Matsumoto, T. Miyatake, I. Nagano, A. Fujita, L. A. Frank, T. Mukai, W. R. Paterson, Y. Saito, S. Machida and R. R. Anderson, Relation Between Electrostatic Solitary Waves and Hot Plasma Flow in the Plasma Sheet Boundary Layer: GEOTAIL Observations, Geophys. Res. Lett., 21, 2919-2922, 1994. 4. Frank, L. A. and W. R. Paterson, Survey of Electron and Ion Bulk Flows in the Distant Magnetotail With the Geotail Spacecraft, Geophys. Res. Lett., 21, 2963-2966, 1994. 5. Frank, L. A., W. R. Paterson, K. L. Ackerson, S. Kokubun, T. Yamamoto, D. H. Fairfield and R. P. Lepping, Observations of Plasmas Associated With the Magnetic Signature of a Plasmoid in the Distant Magnetotail, Geophys. Res. Lett., 21, 2967-2970, 1994. 6. Paterson, W. R. and L. A. Frank, Survey of Plasma Parameters in Earth's Distant Magnetotail With the Geotail Spacecraft, Geophys. Res. Lett., 21, 2971-2974, 1994. 7. Siscoe, G. L., L. A. Frank, K. L. Ackerson and W. R.
    [Show full text]
  • Solar System Exploration Strategic Road Map and Venus Exploration
    Solar System Exploration Strategic Road Map and Venus Exploration Presentation at Lunar and Planetary Science Conference James A. Cutts Solar System Exploration Directorate, JPL James R. Robinson Science Missions Directorate, NASA HQ March 16, 2005 03/16/2005 Predecisional - for discussion purposes only 1 Purpose of this briefing • To inform the Venus Science community about the status of the solar system exploration strategic planning process that is currently being carried out by NASA • To seek inputs on future priorities for Venus exploration for inclusion in the nation’s solar system exploration program for input to this process 03/16/2005 Predecisional - for discussion purposes only 2 Strategic Planning and Venus Exploration? • NASA is conducting a strategic planning activity that builds upon the President’s Vision for Space Exploration published in January 2004. • Three Strategic Road Map teams are formulating plans for exploration of the solar system. – Mars Exploration – Lunar Exploration – Solar System Exploration (covering Venus exploration) – co chaired by • Orlando Figueroa (Assoc Director, Science NASA HQ) • Scott Hubbard (Director, ARC) • Jonathan Lunine, University of Arizona and Chair of NASA Solar System Exploration subcommittee • The Solar System Exploration Road Map team is on a very aggressive schedule. It is scheduled to submit its report for review by the National Research Council by June 1, 2005 An important function of this plan will be to guide the NASA investment in new technologies and related capabilities over the next decade. 03/16/2005 Predecisional - for discussion purposes only 3 Strategic Road Map - Solar System Exploration Committee Members • Orlando Figueroa, NASA Science Mission Directorate co-chair G.
    [Show full text]
  • VOWOX^ >OMRXYVYQSO] PY\ >\KTOM^Y\C .O]SQX PY\ 6 XK
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
    [Show full text]
  • Earth's Magnetosphere and Outer Radiation Belt Under Sub-Alfvénic
    ARTICLE Received 29 Apr 2016 | Accepted 19 Aug 2016 | Published 3 Oct 2016 DOI: 10.1038/ncomms13001 OPEN Earth’s magnetosphere and outer radiation belt under sub-Alfve´nic solar wind Noe´ Lugaz1,2, Charles J. Farrugia1,2, Chia-Lin Huang1,2, Reka M. Winslow1, Harlan E. Spence1,2 & Nathan A. Schwadron1,2 The interaction between Earth’s magnetic field and the solar wind results in the formation of a collisionless bow shock 60,000–100,000 km upstream of our planet, as long as the solar wind fast magnetosonic Mach (hereafter Mach) number exceeds unity. Here, we present one of those extremely rare instances, when the solar wind Mach number reached steady values o1 for several hours on 17 January 2013. Simultaneous measurements by more than ten spacecraft in the near-Earth environment reveal the evanescence of the bow shock, the sunward motion of the magnetopause and the extremely rapid and intense loss of electrons in the outer radiation belt. This study allows us to directly observe the state of the inner magnetosphere, including the radiation belts during a type of solar wind-magnetosphere coupling which is unusual for planets in our solar system but may be common for close-in extrasolar planets. 1 Space Science Center, Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, 8 College Road, Durham, New Hampshire 03824, USA. 2 Department of Physics, University of New Hampshire, Durham, New Hampshire 03824, USA. Correspondence and requests for materials should be addressed to N.L. (email: [email protected]). NATURE COMMUNICATIONS | 7:13001 | DOI: 10.1038/ncomms13001 | www.nature.com/naturecommunications 1 ARTICLE NATURE COMMUNICATIONS | DOI: 10.1038/ncomms13001 nder normal solar wind conditions, a bow shock forms Results sunward of Earth with a subsolar distance of 11–14 Bow shock and magnetopause locations.
    [Show full text]
  • Orbit Determination of the NOZOMI Spacecraft Using Differential VLBI Technique Radio Astronomy Applications Group Kashima Space Research Center IUGG2003, Sapporo
    Orbit Determination of The NOZOMI Spacecraft using Differential VLBI Technique Radio Astronomy Applications Group Kashima Space Research Center IUGG2003, Sapporo (C) ISAS According to the ISAS announcement the NOZOMI has completed its final Earth swingby operation on June 19, and is on its way to Mars. NOZOMI passed within 11,000 km of the NOZOMI Earth in a manuever. (C) ISAS ts Quasar Algonquin (SGL, CRESTech ) tq B: baseline vector Basic Concept of Differential Tomakomai (Hokkaido Univ.) VLBI (DVLBI) observation Mizusawa (NAO) Usuda (ISAS) Gifu Data Sampling Data Sampling (Gifu Univ.) Boards Boards Tsukuba (GSI) K5 VLBI System K5 VLBI System Yamaguchi (Yamaguchi Univ.) Koganei (CRL) Kagoshima(ISAS) Kashima (uplink) (CRL) VLBIVLBI stationsstations participatingparticipating toto DVLBIDVLBI experimentsexperiments Detected NOZOMI fringe Orbit Determination We performed more than 30 differential VLBI (DVLBI) experiments for the NOZOMI spacecraft from September 2002 until June 2003. NOZOMI, which means “Hope” in Japanese, is the Japan's first Mars probe developed and launched by the Institute of Space and Astronautical Science (ISAS). NOZOMI was originally scheduled to reach its destination in October 1998, but an earlier Earth swingby failed to give it sufficient speed, forcing a drastic rescheduling of its flight plan. According to the new trajectory strategy, NOZOMI's arrival at Mars is scheduled early in 2004 through two additional earth swingbys in Dec. 2002 and June 2003. Our main concern was to determine the NOZOMI orbit just before the second earth swingby on June 19, 2003. It was significantly important to get the timing to maneuver the NOZOMI before the swingby. ISAS scientists were afraid that the range and range rate (R&RR) orbit determination might not be available because it was difficult to point the high-gain antenna mounted the spacecraft toward the earth during the period between two swingby events.
    [Show full text]
  • From: Subject
    National Aeronautics and Space Administration Headquarters Washington, DC 20546-0001 OCT 5 1994 Reply to Attn of, ss TO: A/Administrator FROM: S/Associate Administrator for Space Science SUBJECT: Wind Prelaunch Mission Operations Report (MOR) I am pleased to forward with this memorandum, the Prelaunch Mission Operations Report for Wind, the first of NASA's two missions of the Global Geospace Science (GGS) Initiative. The Wind laboratory will contribute to the understanding of the flow and coupling of mass, momentum, and energy from the Sun through the Earth's environment, known as geospace. Data acquired will be analyzed to formulate an understanding of the complex Sun-Earth interaction and their effects on space exploration, communication, and ground-based technology. The spacecraft development was managed by NASA's Goddard Space Flight Center with the Martin Marietta Corporation, Astro-Space Division serving as the prime contractor. Overall programmatic direction was provided by NASA Headquarters, Office of Space Science. The spacecraft will be launched on a Delta II Expendable Launch Vehicle within a November 1-14, 1994, launch window. The Wind spacecraft carries six U.S. instruments, one French instrument, and the first Russian instrument ever to fly on an American satellite. Wind is the second mission of the International Solar Terrestrial Physics (ISTP) Program. The first ISTP mission, Geotail, is a joint project of the Institute of Space and Astronautical Science of Japan and NASA which launched in 1992. Polar is scheduled for a November 1995 launch and will follow Wind as phe second half of the GGS initiative. Wesley T. Huntress, Jr.
    [Show full text]