TABLE OF CONTENTS Operations were initiated on December 6, 1993, after the completion of all spacecraft, ground system, and network in-orbit checkouts. The ACTS system offered considerable flexibility in accommodating multiple simultaneous and independent users in either the BBP, MSM, or mixed modes of operation. Reconfiguration of the spacecraft payload between the various modes of operations was accomplished in less than 30 minutes. During the fall and spring equinox periods, the spacecraft solar panels were eclipsed up to 72 minutes per day. During this time, the payload was shut down. Except for these eclipse shutdowns, experiment operations were conducted 24 hours per day, seven days a week, 365 days per year. Geostationary operations continued until July of 1998.
The ACTS spacecraft was designed for four years of operation in orbit, and was loaded with sufficient hydrazine stationkeeping fuel to provide that length of service. With a continued strong demand for experiment time and interest by industry in continuing to use ACTS as a demonstration vehicle, NASA commissioned Lockheed Martin to investigate the feasibility of operating in an inclined orbit long before the expected depletion of the hydrazine. Studies confirmed the feasibility, and NASA directed Lockheed to implement the necessary autonomous control software to provide accurate pointing with the increased inclination. Meanwhile, NASA equipped the ground stations with tracking capabilities to follow the daily excursions of the spacecraft above and below the equator. The modifications were carried out in the proper sequence to ensure the continuity of the experiments.
After...
