A Miniaturized Two-Axis Ultra Low Latency and Low-Power Sun Sensor for Attitude Determination of Micro Space Probes

This paper describes design, fabrication process, and comprehensive experimental results of a first prototype two-axis miniaturized spiking sun sensor. The sun sensor is a fusion of analog and digital sensor types, such that it takes advantage of spatial selectivity of digital sensors, and is not limited by the global frame rate as in analog sun sensors. It is composed of spiking pixels, and uses a novel Time-to-First-n-Spikes with time-out readout mode to reduce bandwidth consumption and post-processing computation. A thin glass lid with a metal deposited pattern serves as a mask projecting a light pattern onto the sensor. The sun sensor is able to extract a profile of the incident light in the form of time-stamped events. Its latency depends on light intensity, and for medium radiance conditions is equal to 88 mu s. The sun sensor consumes 6.3 mu W in normal operation, and has a precision of 0.98 degrees, and a field of view of 144 degrees. The high temporal resolution, low power consumption, and small QFN64 package make this sun sensor suitable for space probe and sounding rocket applications, where low temporal latency and payload size are essential. This sun sensor is designed to be employed in the sounding rocket attitude determination system as part of the 4DSpace research initiative to study ionospheric plasma disturbances.