INSTRUMENT_HOST_DESC |
Instrument Host Overview
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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.
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