August 23, 2016


CNES contributed to the Soho mission funding through its obligatory contribution to the ESA programme and directly through the national programme for the instruments and the MEDOC centre participation.

Soho is commanded from NASA's Goddard Space Flight Center (GSFC) in Greenbelt, Maryland (USA). Its data is retrieved via the NASA Deep Space Network (DSN) and routed to the Experimenters' Operations Facility (EOF) located at GSFC.
There, the Soho experimenters display on their workstations the images and measurements that are being produced by their instruments. From the EOF, the experimenters point the instruments aboard SOHO to a particular region of the Sun, or change the operating mode of the instruments. The Soho scientists use their instruments very much as an observer would at a ground-based observatory. The EOF is the forum where the experimenters coordinate their observations within SOHO and/or with ground-based solar observatories.
Electronically accessible data catalogues and data banks have been established at the EOF and at several participating institutes, both in the USA and in Europe.

Soho instruments produced a data stream of 200 kilobits per second, which can be continuously transmitted to the DSN stations of Goldstone (USA), Canberra (Australia), and Madrid (Spain).

CNES support to scientific data exploitation

The operating, processing and archiving needs are respectively:

  • to ensure an optimal programming of the on-board instruments, possibly taking into account external information (multi-satellite campaign, special activities) and to retrieve all the information necessary to the scientific processing;
  • to process the available data so as to extract as much scientific information as possible;
  • to document and archive data in order to ensure their long-time storage for future studies.

It is also worth mentioning the original use of SWAN instrument data to produce activity indexes of the hidden side of the Sun. Taking those indexes into account should improve the accuracy of satellite orbit extrapolation, considering that solar activity is an important element of the atmosphere density modelling at the altitude of those satellites.

Participations supported by CNES

The GOLF, EIT and SWAN instruments have French PIs (respectively Alan Gabriel -IAS, Jean-Pierre de la Boudinière -IAS, Eric Quémerais -LATMOS). The LASCO C2 coronograph was built by LAM (Philippe Lamy). The French scientific participations supported by CNES can be summed up as follows:

  • IAS:
    • P. Boumier (GOLF experiment PI and CDS experiment Co-I),
    • F. Auchère (EIT experiment PI),
    • J.C. Vial (SUMER experiment Co-I).
  • LAM:
    • P. Lamy (LASCO experiment Co-PI),
    • A. Maucherat (EIT experiment Co-I).
    • E. Quémerais (SWAN experiment PI).
  • SAp/CEA:
    • S. Turck Chieze (GOLF experiment Co-I).
  • LPSH:
    • M. Pick (LASCO experiment Co-I).

To those participations, MEDOC, which is under IAS (Karine Bocchialini) responsibility, must be added.