Instrument Host Overview
  ========================
 
 
    The SOHO spacecraft was launched in December 1995, however the LASCO
    instrument did not begin regular observing until January 21, 1996. It
    has operated nearly continuously since then except for an interruption
    from June 25, 1998 until October 22, 1998. Smaller unplanned interruptions
    have occurred periodically, and pre-planned interruptions for routine
    maintenance, calibration, and satellite control have occurred, and will
    continue to occur until the conclusion of the mission.
 
    The SOHO spacecraft is three-axis stabilized and pointed towards the
    Sun with an accuracy of +/- 10 arcsec per 15 min. It consists of a
    Payload Module to accommodate the instruments and a Service Module
    carrying the spacecraft subsystems and solar arrays. SOHO occupies a
    halo orbit at the Earth-Sun L1 Lagrangian point to obtain uninterrupted
    sunlight. The design life was two years, but on-board consumables were
    sufficient for at least an extra four years of operations, and the nominal
    mission end is now March 2007.
 
    Twelve instruments comprise the payload, producing a continuous stream
    of data at 40 kbs, except when the solar oscillations imager
    Michelson Doppler Imager (MDI) operates in high-bit-rate mode,
    producing 160 kbs. The high-bit-rate mode is used during scheduled
    daily eight-hour periods or during dedicated campaigns. Magnetic tape
    stores data between telemetry contacts with the Experiment Operations
    Facility, located at NASA-GSFC. For more information, see B. Fleck, V.
    Domingo, and A. I. Poland, eds., Solar Physics, V. 162, 1995
    [FLECKETAL1995].
 
    Author
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    The text in this file was compiled by Matthew Knight, University of
    Maryland
    from online resources made publicly available by the SOHO website.