DOCSLIB.ORG

Mass Variation Observing System by High Low Inter-Satellite Links (MOBILE) – a New Concept for Sustained Observation of Mass Transport from Space

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Mass Variation Observing System by High Low Inter-Satellite Links (MOBILE) – a New Concept for Sustained Observation of Mass Transport from Space J. Geod. Sci. 2019; 9:48–58 Research Article Open Access R. Pail*, J. Bamber, R. Biancale, R. Bingham, C. Braitenberg, A. Eicker, F. Flechtner, T. Gruber, A. Güntner, G. Heinzel, M. Horwath, L. Longuevergne, J. Müller, I. Panet, H. Savenije, S. Seneviratne, N. Sneeuw, T. van Dam, and B. Wouters Mass variation observing system by high low inter-satellite links (MOBILE) – a new concept for sustained observation of mass transport from space DOI: https://doi.org/10.1515/jogs-2019-0006 Abstract: As changes in gravity are directly related to mass Received October 5, 2018; accepted March 10, 2019 variability, satellite missions observing the Earth’s time varying gravity eld are a unique tool for observing mass transport processes in the Earth system, such as the wa- *Corresponding Author: R. Pail: Technical University of Munich, ter cycle, rapid changes in the cryosphere, oceans, and Institute of Astronomical and Physical Geodesy, Munich, Germany, solid Earth processes, on a global scale. The observation E-mail: [email protected] of Earth’s gravity eld was successfully performed by the J. Bamber: University of Bristol, School of Geographical Sciences, GRACE and GOCE satellite missions, and will be contin- Bristol, UK ued by the GRACE Follow-On mission. A comprehensive R. Biancale: Centre National d’Études Spatiales (CNES), Toulouse, France team of European scientists proposed the next-generation R. Bingham: University of Bristol, School of Geographical Sciences, gravity eld mission MOBILE in response to the Euro- Bristol, UK pean Space Agency (ESA) call for a Core Mission in the C. Braitenberg: University of Trieste, Dptm. of Mathematics & Earth frame of Earth Explorer 10 (EE10). MOBILE is based on Sciences, Trieste, Italy the innovative observational concept of a high-low track- A. Eicker: HafenCity Univ. Hamburg, Geodesy and Adjustment The- ing formation with micrometer ranging accuracy, comple- ory, Hamburg, Germany F. Flechtner: GFZ & Technische Univ. Berlin, Chair of Physical mented by new instrument concepts. Since a high-low Geodesy, Berlin, Germany tracking mission primarily observes the radial component T. Gruber: Technical University of Munich, Institute of Astronomical of gravity-induced orbit perturbations, the error structure and Physical Geodesy, Munich, Germany is close to isotropic. This geometry signicantly reduces A. Güntner: Deutsches GeoForschungsZentrum Potsdam, Sect. artefacts of previous along-track ranging low-low forma- Hydrology, Potsdam, Germany G. Heinzel: AEI, Max Planck Inst. for Gravitational Physics, Han- tions (GRACE, GRACE-Follow-On) such as the typical strip- nover, Germany ing patterns. The minimum conguration consists of at M. Horwath: Technische Universität Dresden, Inst. of Planetary least two medium-Earth orbiters (MEOs) at 10000 km al- Geodesy, Dresden, Germany titude or higher, and one low-Earth orbiter (LEO) at 350- L. Longuevergne: Université Rennes, CNRS, Géosciences, Rennes, 400 km. The main instrument is a laser-based distance or France distance change measurement system, which is placed at J. Müller: Leibniz Universität Hannover, Institute of Geodesy, Han- nover, Germany the LEO. The MEOs are equipped either with passive reec- I. Panet: Institut National de l’Information Géographique et tors or transponders. In a numerical closed-loop simula- Forestière, Paris, France tion, it was demonstrated that this minimum conguration H. Savenije: Technical University Delft, Water Resources Section, is in agreement with the threshold science requirements of Delft, Netherlands 5 mm equivalent water height (EWH) accuracy at 400 km S. Seneviratne: ETH Zürich, Institute for Atmospheric and Climate Science, Zürich, Switzerland wavelength, and 10 cm EWH at 200 km. MOBILE provides N. Sneeuw: Universität Stuttgart, Institute of Geodesy, Stuttgart, promising potential future perspectives by linking the con- Germany cept to existing space infrastructure such as Galileo next- T. van Dam: University of Luxembourg, FSTC, Luxembourg generation, as future element of the Copernicus/Sentinel B. Wouters: Univ. Utrecht, Institute for Marine and Atmospheric programme, and holds the potential of miniaturization Research, Utrecht, Netherlands Open Access. © 2019 R. Pail et al., published by De Gruyter. This work is licensed under the Creative Commons Attribution alone 4.0 License. R. Pail et al., Mass variation observing system by high low inter-satellite links (MOBILE) Ë 49 even up to swarm congurations. As such MOBILE can be episodic events such as droughts, oods, earthquakes and considered as a precursor and role model for a sustained volcanos, may relate to the longer-term evolution of the mass transport observing system from space. water-cycle or stress build-up, or resolving the uxes at the boundaries between Earth system components, requires Keywords: mass transport – next-generation gravity mis- high accuracy time-varying gravity coverage over a full sion – gravity eld – high-low tracking – spherical har- range of spatial and temporal scales that is currently un- monics available. Only by mapping time varying gravity with a substantially increased spatial resolution, we can fully un- 1 Introduction derstand how changes in the Earth system develop across scales, how they modify the water uxes, and how they Climate change is one of the biggest societal challenges are related to human activities. The understanding we today. The underlying processes are most frequently re- may achieve is needed to address challenges facing hu- lated to mass variations in the Earth system. Mass is redis- man societies for a sustainable development over the short tributed within the Earth system over a full range of spatial and long term. They include understanding sea level rise, and temporal scales. As mass variations directly induce and assessing the changing water availability for freshwa- changes of the Earth gravity eld, satellite missions ob- ter supply, agriculture and industry, especially in regions serving the Earth’s time varying gravity eld are a unique where freshwater resources are under severe threat, and tool for observing mass redistribution in the Earth sys- anthropogenic demands and stresses are expected to fur- tem, such as the terrestrial water cycle, variations in the ther increase in the decades to come. A minimum of 30 cryosphere and oceans, on a global scale. The dedicated years of observation is necessary to disentangle anthro- gravity mission Gravity Recovery And Climate Experiment pogenic impact from natural variability (GCOS 2016). (GRACE) (Tapley et al. 2014) provided the rst global de- The big success of the GRACE mission led to the im- termination of Earth’s mass transport by measuring spa- plementation of GRACE Follow-On (GRACE-FO) (Flechtner tial and temporal changes in the gravity eld caused by et al. 2016), which was successfully launched in May 2018 mass variations at all depths, while the static gravity eld and will continue the 15 years of mass transport time se- retrieved from the Gravity eld and steady-state Ocean Cir- ries obtained from GRACE. Recently, the United States Na- culation Explorer (GOCE) mission (Drinkwater et al. 2013) tional Academies of Sciences, Engineering, and Medicine has improved our knowledge of the long-term mass distri- published the decadal strategy for Earth observation from bution and has provided the physical reference surface of space (NAS 2018), where mass change was identied as the geoid with a resolution down to 70-80 km. one of the top 5 observables to be implemented by future This is key information, as direct observations of mass US Earth observation missions in order to ensure conti- variations and mass transport are dicult to obtain. For nuity and enable long-term mass budget analyses of the example, almost no direct observations of evapotranspira- Earth system. Again it is proposed to plan for a single- tion are available. Storage changes in deep soil layers and pair mission, which should follow GRACE-FO. This clearly groundwater are mostly inaccessible to conventional ob- demonstrates the importance of sustained gravity moni- servation techniques. Current estimates for soil moisture toring from space. derived from remote sensing satellites are usually based On European side, during the last couple of years on the measurement of the uppermost few centimeters several attempts have been made by the gravity-related of soil, depending on the penetration depth, leaving the science community to propose a next-generation gravity largest part of the water column unexplored. The same eld mission as an Earth Explorer mission to the Euro- holds for the deep ocean circulation, an essential but hid- pean Space Agency (ESA). The proposed mission constel- den part of the climate system, playing an important role lations diered from the typical GRACE-type concept of in heat transport and carbon dioxide sequestration. Addi- an in-line pair, with which only the along-track compo- tional limitations to a closure of the global water balance nent of the Earth’s gravity eld can be observed, leading are imposed by the scarcity of data on freshwater run-o, to a very anisotropic error structure and the typical strip- limitations of satellite altimetry along coasts and ice sheet ing patterns in the resulting temporal gravity solutions. In margins, and in high latitudes. 2010 the mission proposal “e.motion – Earth System Mass A resolution adopted by the Council of the Inter- Transport Mission” (Panet et al. 2012) was submitted in re- national Union of Geodesy and Geophysics (IUGG 2015) sponse to ESA’s Earth Explorer 8 call. It was based on a calls for sustained observing of mass transport processes satellite pair in pendulum conguration, where the sec- from space (Pail et al. 2015a). Understanding how extreme ond satellite performs a pendulum motion with respect to 50 Ë R. Pail et al., Mass variation observing system by high low inter-satellite links (MOBILE) the leading satellite, thus observing not only the along- tem, and addresses a number of Essential Climate Vari- track, but also parts of the cross-track component. In 2016 ables (ECV; (GCOS 2016)) such as groundwater, snow e.motion2 (Gruber et al.
Load more

Recommended publications
  • The Lageos System
    NASA TECHNICAL NASA TM X-73072 MEMORANDUM (NASA-TB-X-73072) liif LAGECS SYSTEM (NASA) E76-13179 68 p BC $4.5~ CSCI 22E Thls Informal documentation medium is used to provide accelerated or speclal release of technical information to selected users. The contents may not meet NASA formal editing and publication standards, my be re- vised, or may be incorporated in another publication. THE LAGEOS SYSTEM Joseph W< Siry NASA Headquarters Washington, D. C. 20546 NATIONAL AERONAUTICS AND SPACE ADMlNlSTRATlCN WASHINGTON, 0. C. DECEMBER 1975 1. i~~1Yp HASA TW X-73072 4. Titrd~rt. 5.RlpDltDM December 1975 m UG~SSYSEM 6.-0-cad8 . 7. A#umrtsI ahr(onninlOlyceoa -* Joseph w. Siry . to. work Uld IYa n--w- WnraCdAdbar I(ASA Headquarters Office of Applications . 11. Caoa oc <irr* 16. i+ashingtcat, D. C. 20546 12TmdRlponrrd~~ 12!3mnm&@~nsnendAddrs Technical Memorandum 1Sati-1 Aeronautics and Space Adninistxation Washington, D. C. 20546 14. sponprip ~gmcvu 15. WDPa 18. The LAGEOS system is defined and its rationale is daveloped. This report was prepared in February 1974 and served as the basis for the LAGMS Satellite Program development. Key features of the baseline system specified then included a circular orbit at 5900 km altitude and an inclination of lloO, and a satellite 60 cm in diameter weighing same 385 kg and mounting 440 retro- reflectors, each having a diameter of 3.8 cm, leaving 30% of the spherical surface available for reflecting sunlight diffusely to facilitate tracking by Baker-Nunn cameras, The satellite weight was increased to 411 kg in the actual design thr~aghthe addition of a 4th-stage apogee-kick motor.
    [Show full text]
  • Lageos Orbit Decay Due to Infrared Radiation from Earth
    https://ntrs.nasa.gov/search.jsp?R=19870006232 2020-03-20T12:07:45+00:00Z View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by NASA Technical Reports Server Lageos Orbit Decay Due to Infrared Radiation From Earth David Parry Rubincam JANUARY 1987 NASA Technical Memorandum 87804 Lageos Orbit Decay Due to Infrared Radiation From Earth David Parry Rubincam Goddard Space Flight Center Greenbelt, Maryland National Aeronautics and Space Administration Goddard Space Flight Center Greenbelt, Maryland 20771 1987 1 LAGEOS ORBIT DECAY r DUE TO INFRARED RADIATION FROM EARTH by David Parry Rubincam Geodynamics Branch, Code 621 NASA Goddard Space Flight Center Greenbelt, Maryland 20771 i INTRODUCTION The Lageos satellite is in a high-altitude (5900 km), almost circular orbit about the earth. The orbit is retrograde: the orbital plane is tipped by about 110 degrees to the earth’s equatorial plane. The satellite itself consists of two aluminum hemispheres bolted to a cylindrical beryllium copper core. Its outer surface is studded with laser retroreflectors. For more information about Lageos and its orbit see Smith and Dunn (1980), Johnson et al. (1976), and the Lageos special issue (Journal of Geophysical Research, 90, B 11, September 30, 1985). For a photograph see Rubincam and Weiss (1986) and a structural drawing see Cohen and Smith (1985). Note that the core is beryllium copper (Johnson et ai., 1976), and not brass as stated by Cohen and Smith (1985) and Rubincam (1982). See Table 1 of this paper for other parameters relevant to Lageos and the study presented here.
    [Show full text]
  • The Evolution of Earth Gravitational Models Used in Astrodynamics
    JEROME R. VETTER THE EVOLUTION OF EARTH GRAVITATIONAL MODELS USED IN ASTRODYNAMICS Earth gravitational models derived from the earliest ground-based tracking systems used for Sputnik and the Transit Navy Navigation Satellite System have evolved to models that use data from the Joint United States-French Ocean Topography Experiment Satellite (Topex/Poseidon) and the Global Positioning System of satellites. This article summarizes the history of the tracking and instrumentation systems used, discusses the limitations and constraints of these systems, and reviews past and current techniques for estimating gravity and processing large batches of diverse data types. Current models continue to be improved; the latest model improvements and plans for future systems are discussed. Contemporary gravitational models used within the astrodynamics community are described, and their performance is compared numerically. The use of these models for solid Earth geophysics, space geophysics, oceanography, geology, and related Earth science disciplines becomes particularly attractive as the statistical confidence of the models improves and as the models are validated over certain spatial resolutions of the geodetic spectrum. INTRODUCTION Before the development of satellite technology, the Earth orbit. Of these, five were still orbiting the Earth techniques used to observe the Earth's gravitational field when the satellites of the Transit Navy Navigational Sat­ were restricted to terrestrial gravimetry. Measurements of ellite System (NNSS) were launched starting in 1960. The gravity were adequate only over sparse areas of the Sputniks were all launched into near-critical orbit incli­ world. Moreover, because gravity profiles over the nations of about 65°. (The critical inclination is defined oceans were inadequate, the gravity field could not be as that inclination, 1= 63 °26', where gravitational pertur­ meaningfully estimated.
    [Show full text]
  • Draft American National Standard Astrodynamics
    BSR/AIAA S-131-200X Draft American National Standard Astrodynamics – Propagation Specifications, Test Cases, and Recommended Practices Warning This document is not an approved AIAA Standard. It is distributed for review and comment. It is subject to change without notice. Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are aware and to provide supporting documentation. Sponsored by American Institute of Aeronautics and Astronautics Approved XX Month 200X American National Standards Institute Abstract This document provides the broad astrodynamics and space operations community with technical standards and lays out recommended approaches to ensure compatibility between organizations. Applicable existing standards and accepted documents are leveraged to make a complete—yet coherent—document. These standards are intended to be used as guidance and recommended practices for astrodynamics applications in Earth orbit where interoperability and consistency of results is a priority. For those users who are purely engaged in research activities, these standards can provide an accepted baseline for innovation. BSR/AIAA S-131-200X LIBRARY OF CONGRESS CATALOGING DATA WILL BE ADDED HERE BY AIAA STAFF Published by American Institute of Aeronautics and Astronautics 1801 Alexander Bell Drive, Reston, VA 20191 Copyright © 200X American Institute of Aeronautics and Astronautics All rights reserved No part of this publication may be reproduced in any form, in an electronic retrieval
    [Show full text]
  • Determination of the Geocentric Gravitational Constant from Laser
    VOL. 5, NO. 12 GEOPHYSICALRESEARCH LETTERS DECEMBER1978 DETERMINATION OF THE GEOCENTRI½ GRAVITATIONAL CONSTANT FROM LASER RANGING ON NEAR-EARTH SATELLITES 1 2 • Francis 3. Lerch, Roy E. Laubscher, Steven M. Klosko 1 1 David E. Smith, Ronald Kolenkiewicz, Barbara H. Putney, 1 2 James G. Marsh, and Joseph E. Brownd 1 GeodynamicsBranch, GoddardSpace Flight Center Computer Sciences Corporation, Silver Spring, Maryland 3EG&GWashington Analytical ServicesCenter, Inc., Riverdale, Maryland Abstract. Laser range observations taken on earth plus moon Ms/(Me + Mm) of 328900.50+ the near-earth satellites of Lageos (a -- 1.92 .03. Assuming the AU and the IAG value of c, e.r.), Starlette (a -- 1.15 e.r.), BE-C (a = 1.18 this yields a value of GM of 398600.51 + .03 when e.r.) and Geos-3 (a -- 1.13 e.r.), have been using an earth to moon mass ratio of 81.3007 combined to determine an improved value of the (Wong and Reinbold, 1973). geocentric gravitational constant (GM). The In this paper we use near-earth laser ranging value of GM is 398600.61 km3/sec2, based upon a in a new determination of GM. These results speed of light, c, of 299792.5 kin/sec. Using the basically confirm those obtained from inter- planetary and lunar laser experiments, but km/secIAGadopted scales valueGM to of 398600.44 c equallin• km /sec299792.458 2. The further reduces the uncertainty of GM. uncertainty in this value is assessed to be + .02 km3/sec2. Determinations of GM from the-data Near Earth Laser Ranging Experiment. The taken on these four satellites individually show experiment reported here was performed in the variations of only .04 km3/sec2 from the combined development of the recent Goddard Earth Models result.
    [Show full text]
  • A New Laser-Ranged Satellite for General Relativity and Space Geodesy IV
    A new laser-ranged satellite for General Relativity and Space Geodesy IV. Thermal drag and the LARES 2 space experiment 1,2 3 3 Ignazio Ciufolini∗ , Richard Matzner , Justin Feng , David P. Rubincam4, Erricos C. Pavlis5, Giampiero Sindoni6, Antonio Paolozzi6 and Claudio Paris2 1Dip. Ingegneria dell'Innovazione, Universit`adel Salento, Lecce, Italy 2Museo della fisica e Centro studi e ricerche Enrico Fermi, Rome, Italy 3Theory Group, University of Texas at Austin, USA 4NASA Goddard Space Flight Center, Greenbelt, Maryland, USA 5Goddard Earth Science and Technology Center (GEST), University of Maryland, Baltimore County, USA 6Scuola di Ingegneria Aerospaziale , Sapienza Universit`adi Roma, Italy In three previous papers we presented the LARES 2 space experiment aimed at a very accurate test of frame-dragging and at other tests of fundamental physics and measurements of space geodesy and geodynamics. We presented the error sources in the LARES 2 experiment, its error budget, Monte Carlo simulations and covariance analyses confirming an accuracy of a few parts per thousand in the test of frame-dragging, and we treated the error due to the uncertainty in the de Sitter effect, a relativistic orbital perturbation. Here we discuss the impact in the error budget of the LARES 2 frame-dragging experiment of the orbital perturbation due to thermal drag or thermal thrust. We show that the thermal drag induces an uncertainty of about one part per thousand in the LARES 2 frame-dragging test, consistent with the error estimates in our previous papers. arXiv:1911.05016v1 [gr-qc] 12 Nov 2019 1 Introduction: thermal drag and LARES 2 We recently described a new satellite experiment to measure the General Relativistic phenomenon know as frame dragging, or the Lense-Thirring effect.
    [Show full text]
  • LARES, Laser Relativity Satellite
    LARES,LARES, LaserLaser RelativityRelativity Satellite:Satellite: TowardsTowards aa OneOne PercentPercent MeasurementMeasurement ofof FrameFrame DraggingDragging byby LAGEOS,LAGEOS, LAGEOSLAGEOS 2,2, LARESLARES andand GRACEGRACE by ΙΙΙgnazio Ciufolini presented by Rolf Koenig (Univ. Salento) (GFZ) A. Paolozzi*, E. Pavlis* , R. Koenig* , J. Ries* , R. Matzner* , G. Sindoni*, H. Neumayer* *Sapienza Un. Rome, *Maryland Un ., *GFZ-German Research Centre for Geosciences-Potsdam, *Un. Texas Austin 17 Int. Workshop on Laser Ranging, Bad Kötzting, 16-3-2010 ContentContent BRIEF INTRODUCTION ON FRAME -DRAGGING and GRAVITOMAGNETISM EXPERIMENTS * The 2004 -2007 measurements using the GRACE Earth ’s gravity models and the LAGEOS satellites • * LARES: 2011 DRAGGINGDRAGGING OFOF INERTIALINERTIAL FRAMESFRAMES ((FRAMEFRAME --DRAGGINGDRAGGING asas EinsteinEinstein namednamed itit inin 1913)1913) The “local inertial frames ” are freely falling frames were, locally, we do not “feel ” the gravitational field, examples: an elevator in free fall, a freely orbiting spacecraft. In General Relativity the axes of the local inertial frames are determined by gyroscopes and the gyroscopes are dragged by mass -energy currents, e.g., by the Earth rotation. Thirring 1918 Braginsky, Caves and Thorne 1977 Thorne 1986 I.C. 1994-2001 GRAVITOMAGNETISM:GRAVITOMAGNETISM: ff ramerame --draggingdragging isis alsoalso calledcalled gravitomagnetismgravitomagnetism forfor itsits formalformal analogyanalogy withwith electrodynamicselectrodynamics InIn electrodynamicselectrodynamics
    [Show full text]
  • The Effect of Variable Gravity on the Fractal Growth
    1 Fractal Growth on the Surface of a Planet and in Orbit around it 1Ioannis Haranas, 2Ioannis Gkigkitzis, 3Athanasios Alexiou 1Dept. of Physics and Astronomy, York University, 4700 Keele Street, Toronto, Ontario, M3J 1P3, Canada 2Departments of Mathematics and Biomedical Physics, East Carolina University, 124 Austin Building, East Fifth Street, Greenville, NC 27858-4353, USA 3Department of Informatics, Ionian University, Plateia Tsirigoti 7, Corfu, 49100, Greece Abstract: Fractals are defined as geometric shapes that exhibit symmetry of scale. This simply implies that fractal is a shape that it would still look the same even if somebody could zoom in on one of its parts an infinite number of times. This property is also called self-similarity with several applications including nano-pharmacology and drug nanocarriers. We are interested in the study of the properties of fractal aggregates in a microgravity environment above an orbiting spacecraft. To model the effect we use a complete expression for the gravitational acceleration. In particular on the surface of the Earth the acceleration is corrected for the effect of oblateness and rotation. In the gravitational acceleration the effect of oblateness can be modeled with the inclusion of a term that contains the J2 harmonic coefficient, as well as a term that depends on the square of angular velocity of the Earth. In orbit the acceleration of gravity at the point of the spacecraft is a function of the orbital elements and includes only in our case the J2 harmonic since no Coriolis force is felt by the spacecraft. Using the fitting parameter d =3.0 we have found that the aggregate monomer number N is not significantly affected and exhibits a minute 0.0001% difference between the geocentric and areocentric latitudes of 90 and 0.
    [Show full text]
  • Impact of the Atmospheric Drag on Starlette, Stella, Ajisai, and Lares Orbits
    ARTIFICIAL SATELLITES, Vol. 50, No. 1 – 2015 DOI: 10.1515/arsa-2015-0001 IMPACT OF THE ATMOSPHERIC DRAG ON STARLETTE, STELLA, AJISAI, AND LARES ORBITS Krzysztof So´snica 1,2 1 Astronomical Institute, University of Bern, Bern, Switzerland 2 Institute of Geodesy and Geoinformatics, Wroclaw University of Environmental and Life Sciences, Wroclaw, Poland e-mail: [email protected], [email protected] ABSTRACT. The high-quality satellite orbits of geodetic satellites, which are deter- mined using Satellite Laser Ranging (SLR) observations, play a crucial role in providing, e.g., low-degree coefficients of the Earth’s gravity field including geocenter coordinates, Earth rotation parameters, as well as the SLR station coordinates. The appropriate mod- eling of non-gravitational forces is essential for the orbit determination of artificial Earth satellites. The atmospheric drag is a dominating perturbing force for satellites at low altitudes up to about 700-1000 km. This article addresses the impact of the atmospheric drag on mean semi-major axes and orbital eccentricities of geodetic spherical satellites: Starlette, Stella, AJISAI, and LARES. Atmospheric drag causes the semi-major axis de- cays amounting to about Δa = −1.2, −12, −14, and −30 m/year for LARES, AJISAI, Starlette, and Stella, respectively. The density of the upper atmosphere strongly depends on the solar and geomagnetic activity. The atmospheric drag affects the along-track or- bit component to the largest extent, and the out-of-plane to a small extent, whereas the radial component is almost unaffected by the atmospheric drag. Keywords: Satellite Geodesy, Atmospheric Drag, SLR, Mean Orbital Elements 1.
    [Show full text]
  • Lageos 2 Spin Rate and Orientation
    Lageos 2 spin rate and orientation Roger Wood 1, Toshimichi Otsubo 2 & Robert Sherwood 1 1 NERC Space Geodesy Facility, UK 2 Communications Research Laboratory, Japan Abstract The Herstmonceux photometer system (which allows brightness measurements of sunlit satellites to be made simultaneously with laser ranging) has been upgraded to provide 1 millisecond time resolution. Precise timing of solar glints from the front faces of the corner-cube reflectors on Lageos 2 over a 2-year period has yielded a detailed record of the slowing of the satellite's rotation and an accurate determination of the precessional behaviour of the spin axis. These data make possible precise modelling of the non-gravitational forces on the satellite and contribute powerfully to evaluations of their evolution in the long-term. Introduction Each Lageos satellite (see e.g. Minott et al. 1993) carries 426 retro-reflectors inset in the outer aluminium shell surrounding a solid brass cylinder. Each reflector is mounted with its front face perpendicular to the radius vector at the mounting point. Reflectors are distributed over the whole surface of the sphere in rings, equally spaced along lines of “latitude” (where the “equator” is the great circle perpendicular to the axis of rotation of the satellite). Immediately either side of the “equator” are rings of 32 reflectors: then, moving towards the “poles”, successive rings have 32, 31, 31, 27, 23, 18, 12, 6, 1 (at the “pole”) reflectors, giving a total of 213 in each hemisphere. 422 of the reflectors are made of fused silica and 4 of germanium. Figure 1 shows the resultant distribution of reflectors on the surface of the satellite.
    [Show full text]
  • Now 40, NASA's LAGEOS Set the Bar for Studies of Earth 5 May 2016
    Now 40, NASA's LAGEOS set the bar for studies of Earth 5 May 2016 satellite is passive, with no on-board sensors or electronics and no moving parts. Its brass core is covered by an aluminum shell that is dotted with 426 retroreflectors, making the satellite look like a giant golf ball. "LAGEOS is elegantly simple – a ball covered with reflecting prisms," said Stephen Merkowitz, manager of NASA's Space Geodesy Project at the agency's Goddard Space Flight Center in Greenbelt, Maryland. "But it set a new standard for laser ranging and has provided 40 years of continuity for these measurements." The satellite was launched from the Vandenberg The surface of LAGEOS is dotted with 426 cube-corner Air Force Base in California. The design, prisms to reflect laser pulses transmitted from ground development and construction of the orbiter was stations on Earth. One sector of a model is shown here. managed by NASA's Marshall Space Flight Center With LAGEOS, the accuracy of laser ranging in Huntsville, Alabama. measurements improved from about 3 feet (1 meter) to less than half an inch (1 centimeter). Credit: NASA's LAGEOS travels in a stable circular, pole-to-pole Goddard Space Flight Center orbit more than 3,600 miles (5,900 kilometers) above Earth's surface. At this altitude – medium Earth orbit – the satellite feels very little On May 4, 1976, NASA launched a cannonball- atmospheric drag and can be observed by ground shaped satellite that transformed studies of Earth's stations on different continents simultaneously. shape, rotation and gravity field.
    [Show full text]
  • Iris-LAGEOS 2 Mission
    1991 (28th) Space Achievement: A Global The Space Congress® Proceedings Destiny Apr 24th, 2:00 PM - 10:00 AM Paper Session II-A - Iris-LAGEOS 2 Mission Roberto Ibba Italian Space Agency, Rome, Italy Giovanni Rum Italian Space Agency, Rome, Italy Franco Varesio Italian Space Agency, Rome, Italy Enrico Buratti Italian Space Agency, Rome, Italy Pratizia Buratti Italian Space Agency, Rome, Italy Follow this and additional works at: https://commons.erau.edu/space-congress-proceedings Scholarly Commons Citation Ibba, Roberto; Rum, Giovanni; Varesio, Franco; Buratti, Enrico; and Buratti, Pratizia, "Paper Session II-A - Iris-LAGEOS 2 Mission" (1991). The Space Congress® Proceedings. 17. https://commons.erau.edu/space-congress-proceedings/proceedings-1991-28th/april-24-1991/17 This Event is brought to you for free and open access by the Conferences at Scholarly Commons. It has been accepted for inclusion in The Space Congress® Proceedings by an authorized administrator of Scholarly Commons. For more information, please contact [email protected]. Canaveral Council of Technical Societies Announces the Twenty-Eighth Space Congress April 23, 24, 25, 26, 1991 P.O. Box 321333, Cocoa Beach, FL 32932 COCOA iiACH. fl PAPER presented by Alenia Alenia Spazio IRIS-LAGEOS 2 MISSION »AUTHORS Roberta IBBA, Giovanni RUM (ASI) Franco VARESIO, Enrico BERUTO Patrizia BURATTI (Alenia) • ADDRESS ALENIA Alenia Spazio Corso Marche 41 10146 TORINO (Italy) • TELEPHONE ill.-71Ji.W5/ 7UQ.708 • FAX 011-723307/724807 •TELEX 221235 AERSPZ I 4-13 IRfS-LAGEOS 2 MISSION Roberta IBBA, Giovanni RUM Franco VARESIO, Enrico BERUTO, Patrizia BURATTI A.S.I. ALENIA(*) Agenzia Spaziale Italiana Alenia Spazio Roma - Italy Torino - Italy ABSTRACT The developing and launching of LAGEOS 2 must be considered an important step in the evolution of Italian space and scientific activities.
    [Show full text]