Earth Sensor

Earth-Pointing Sensor for High-Gain Antenna Coarse Alignment

The Earth-pointing sensor is an optical instrument that establishes an Earth-direction reference to achieve coarse 0.5-degree alignment for high-gain antennas prior to fine radio-frequency tracking. Weighing 1 kg and drawing 2 W of power, the unit uses an optical baffle and an infrared or visible-band detector array to track Earth disk position or thermal radiance limb profiles. Lunar deployment requires radiation-tolerant variants to prevent detector aging across a 20-year operational lifetime. At installations such as the lunar south pole, the sensor must also account for geometric shifts where Earth visibility depends directly on the lunar libration phase.

Earth-pointing sensor (IR / visible) providing Earth-direction reference for coarse HGA pre-pointing before fine RF tracking takes over.