Solar Physics

, Volume 279, Issue 1, pp 127–152 | Cite as

Coronal Density Structures and CMEs: Superior Solar Conjunctions of Mars Express, Venus Express, and Rosetta: 2004, 2006, and 2008

  • Martin PätzoldEmail author
  • Matthias Hahn
  • Silvia Tellmann
  • Bernd Häusler
  • Michael K. Bird
  • G. Leonard Tyler
  • Sami W. Asmar
  • Bruce T. Tsurutani


Coronal radio-sounding experiments were carried out using the S-band (2.3 GHz) and X-band (8.4 GHz) signals of the ESA Mars Express, Venus Express, and Rosetta spacecraft during five superior conjunctions occurring in 2004, 2006 (3×), and 2008/2009. Differential frequency and propagation delay (ranging) observations were recorded during these opportunities over the better part of a solar cycle, yielding information on the large-scale structure of the coronal electron-density distribution and its variations, including fluctuations on time scales from seconds to hours. These results concern primarily regions of slow solar wind because the radio propagation path is generally confined to the low heliolatitude regions by the conjunction. The mean frequency fluctuation and total electron content are determined as a function of heliocentric distance, and, with a few exceptions caused by streamers and CMEs, are found to be consistent with previous results from experiments on Ulysses. Dense coronal streamers and several coronal mass ejection (CME) events were identified in the radio-frequency data, some of which were observed in white light by the LASCO coronagraphs onboard SOHO. For those events with sufficient mutual coverage, good correlations are found between the electron-content fluctuations and structure imaged by the LASCO instrument.


Corona Superior conjunction CME 



The Mars Express Radio Science Experiment (MaRS), the Rosetta Radio Science Investigations (RSI), and the Venus Express Radio Science Experiment (VeRa) are funded by the German Space Agency (DLR) under grants 50QP9909, 50QM0701 and 50OV0601. Support for Mars Express Radio Science at Stanford University is provided by NASA through JPL Contract 1217744. Support for the Multimission Radio Science Support Team is provided by NASA/JPL. Portions of this research were performed at the Jet Propulsion Laboratory, California Institute of Technology under contract with NASA.

We thank everyone involved in the Mars Express, Rosetta, and Venus Express projects at ESTEC, ESOC, ESAC, JPL, and the ESTRACK and DSN ground stations for their continuous support.

The SOHO/LASCO data used here are produced by a consortium of the Naval Research Laboratory (USA), Max-Planck-Institut für Sonnensystemforschung (Germany), Laboratoire d’Astronomie (France), and the University of Birmingham (UK). The SOHO/LASCO CME catalog is generated and maintained at the CDAW Data Center by NASA and The Catholic University of America in cooperation with the Naval Research Laboratory. SOHO is a project of international cooperation between ESA and NASA. The Solar Irradiance Platform historical irradiances plotted in Figure 2 are provided courtesy of W. Kent Tobiska and Space Environment Technologies. These historical irradiances have been developed with partial funding from the NASA UARS, TIMED, and SOHO missions.

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Copyright information

© Springer Science+Business Media B.V. 2012

Authors and Affiliations

  • Martin Pätzold
    • 1
    Email author
  • Matthias Hahn
    • 1
  • Silvia Tellmann
    • 1
  • Bernd Häusler
    • 2
  • Michael K. Bird
    • 3
  • G. Leonard Tyler
    • 4
  • Sami W. Asmar
    • 5
  • Bruce T. Tsurutani
    • 5
  1. 1.Rheinisches Institut für UmweltforschungCologneGermany
  2. 2.Institut für RaumfahrttechnikUniversität der Bundeswehr MünchenNeubibergGermany
  3. 3.Argelander-Institut für AstronomieUniversität BonnBonnGermany
  4. 4.Department of Electrical EngineeringStanford UniversityStanfordUSA
  5. 5.Jet Propulsion LaboratoryCaltechPasadenaUSA

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