Mixed fortunes

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Having launched the six packages for the Department of Defense (and unfortunately lost half of them), OSC turned its attention to two long-delayed satellites for NASA. A Pegasus XL successfully released the Total Ozone Mapping Spectrometer Earth Probe on 1 July 1996. Another launched the Fast Auroral Snapshot Explorer for the Small Explorer series on 21 August. On 4 November, another vehicle attained the desired 550-kilometre circular orbit, but the system in the third stage that was to provide power for 'transient events' failed, inhibiting the pyrotechnics from releasing the two satellites.37^8 The fault was detected towards the end of the first orbit, when radar tracking 'saw' only one object. Telemetry from Argentina's SAC B satellite confirmed that it was still in the forward position of the dual-payload dispenser. A ground command was able to open the satellite's solar panels, but its attitude control system was overwhelmed by the mass of the spent stage, and as this tumbled it cast a shadow over the solar arrays and caused the satellite to drain its battery. The High-Energy Transient Explorer built for NASA by the Massachusetts Institute of Technology was worse off. It was inside a container further aft, and its transmission

The HETE and SAC B satellites are stacked on the nose of a Pegasus, with HETE (aft) being completely enclosed within the deployment system.

was masked. Unable to deploy its solar panels, it soon exhausted its battery.39 After a string of successes, on 4 March 1999 the WIRE satellite for astronomical studies failed soon after being released into the desired orbit, when it jettisoned a cover three days ahead of schedule, allowing heat to vent the coolant for its telescope and causing it to spin out of control.40 The next flight on 18 May successfully inserted the TERRIERS satellite for ionospheric studies into orbit, but an attitude control fault prevented the satellite from maintaining its solar panels facing the Sun, and within hours it was dead, having exhausted its battery.41

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