Flight Results from a Novel Magnetic Actuator on the LatinSat Spacecraft

The LatinSat-A and –B spacecraft were launched into low Earth orbit in December of 2002. Built by SpaceQuest, these 11 kg microsatellites carry commercial UHF payloads. Their attitude control systems employ a novel magnetic actuator that can provide large torques while using very little power. At the core of the device is a rod of Alnico alloy, capable of storing a 13 Am2 magnetic dipole. Copper windings around this rod connect to a high-voltage pulse generator. High power pulses can degauss or permanently reverse the polarity of the magnet. A hall-effect sensor provides magnetic field telemetry to the flight computer, and allows for closed-loop control. Once the polarity of the rod is set, no additional power is required to maintain it. Previous SpaceQuest microsatellites have used permanent magnets in their ACS to align them with the Earth’s field. These spacecraft complete two pitch rotations per orbit, so that the side that faces the Earth over the northern hemisphere faces space over the southern hemisphere. The LatinSats can degauss and then reverse their magnets each time they pass over the magnetic equator. This should allow a single side to face the Earth at all times