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Introduction

The SOHO mission consists of three phases: the Launch and Early Operations Phase (LEOP), the Transfer Trajectory Phase (TTP) and the Halo Orbit Phase (HOP). The HOP consist of two subphases, the Commissioning and Verification subphase (first month of HOP) and the Mission Operations subphase. The nominal mission lasts 2 years.

The SOHO spacecraft is controlled from the SOHO Mission Operations Control Center (SMOCC) located at the NASA Goddard Space Flight Center (GSFC). The UVCS instrument is operated from the SOHO Experiment Operations Facility (EOF) located near the SMOCC. All communication with the spacecraft occurs via NASA's Deep Space Network (DSN). Instrument commanding and realtime telemetry reception are possible only when the DSN is in contact with the SOHO spacecraft:

1) During 10 months per year the DSN will provide Nominal S/C Coverage, which consists of one 8-hour contact period and three 1.3-hour contact periods every day (7 days/week). The short contacts are used for tape dumps. The precise times of contact depend on DSN availability, but generally the 8-hour contact will occur during daylight hours at GSFC and one of the 1.3-hour contacts will immediately precede the 8-hour contact.

2) During 2 month per year the DSN will provide Continuous S/C Coverage (24 hours per day).



Peter Smith
Fri Jan 17 12:11:15 EST 1997