Session
Technical Session I: Hardware in Space
Abstract
The ORBCOMM Flight Model (FM) 1&2 and MicroLab I spacecraft were flawlessly launched by a Pegasus® vehicle on April 3, 1995. Following sequential separation from the Pegasus third stage, the spacecraft deployed solar arrays and antenna assemblies, autonomously de-tumbled, and acquired sun-nadir attitude. Both ORBCOMM spacecraft connected automatically with a Gateway Earth Station (GES) about 8 hours after launch. Nominal early passes focused on post-launch housekeeping tasks. However, a series of anomalies developed: including loss of gateway uplink, gateway downlink transmitter oscillation, poor GPS position fixing, subscriber downlink transmitter lock-up, and several software problems. All these conditions were unique to the space environment or resulted from minor design changes or oversights. Eventually the spacecraft were recovered from their outages and the causes conclusively determined. Throughout this time, the spacecraft housekeeping subsystems continued to function nominally with a high degree of autonomy. Following maneuvers and testing, the satellites were delivered to ORBCOMM Global on August 3, 1995.
ORBCOMM Satellites Launch and Initial Flight Operations
The ORBCOMM Flight Model (FM) 1&2 and MicroLab I spacecraft were flawlessly launched by a Pegasus® vehicle on April 3, 1995. Following sequential separation from the Pegasus third stage, the spacecraft deployed solar arrays and antenna assemblies, autonomously de-tumbled, and acquired sun-nadir attitude. Both ORBCOMM spacecraft connected automatically with a Gateway Earth Station (GES) about 8 hours after launch. Nominal early passes focused on post-launch housekeeping tasks. However, a series of anomalies developed: including loss of gateway uplink, gateway downlink transmitter oscillation, poor GPS position fixing, subscriber downlink transmitter lock-up, and several software problems. All these conditions were unique to the space environment or resulted from minor design changes or oversights. Eventually the spacecraft were recovered from their outages and the causes conclusively determined. Throughout this time, the spacecraft housekeeping subsystems continued to function nominally with a high degree of autonomy. Following maneuvers and testing, the satellites were delivered to ORBCOMM Global on August 3, 1995.
