A report describes the development of a compact micro Sun sensor for use as a part of the attitude determination subsystem aboard future miniature spacecraft and planetary robotic vehicles.
The prototype unit has a mass of only 9 g, a volume of only 4.2 cm3, a power consumption of only 30 mW, and a 120∞ field of view. The unit has demonstrated an accuracy of 1 arc-minute. The unit consists of a multiple-pinhole camera: A micromachined mask containing a rectangular array of microscopic pinholes, machined utilizing the microectromechanical systems (MEMS), is mounted in front of an active-pixel sensor (APS) image detector. The APS consists of a 512 x 512-pixel array, on-chip 10-bit analog to digital converter (ADC), on-chip bias generation, and on-chip timing control for self-sequencing and easy programmability. The digitized output of the APS is processed to compute the centroids of the pinhole Sun images on the APS. The Sun angle, relative to a coordinate system fixed to the sensor unit, is then computed from the positions of the centroids.
This work was done by Sohrab Mobasser, Carl Liebe, Youngsam Bae, Jeffrey Schroeder, and Chris Wrigley of Caltech for NASA's Jet Propulsion Laboratory. For further information, access the Technical Support Package (TSP) free on-line at www.techbriefs.com/tsp under the Electronics /Computers category.
NPO-30867
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Micro Sun Sensor for Spacecraft
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Overview
The document discusses the development of a compact micro Sun sensor designed for use in miniature spacecraft and planetary robotic vehicles, developed by NASA’s Jet Propulsion Laboratory (JPL). This innovative sensor addresses the need for smaller, lighter, and more efficient sun sensors that can be integrated into future micro/nano spacecraft and rovers.
The micro Sun sensor prototype has a mass of only 9 grams, a volume of 4.2 cm³, and consumes just 30 mW of power, making it significantly smaller and lighter than conventional digital sun sensors. It features a 120° field of view and has demonstrated an impressive accuracy of 1 arc-minute. The sensor operates using a multiple-pinhole camera design, which includes a micromachined mask with a rectangular array of microscopic pinholes, fabricated using microelectromechanical systems (MEMS) technology. This mask is positioned in front of an active-pixel sensor (APS) image detector, which consists of a 512×512-pixel array, an on-chip 10-bit analog-to-digital converter (ADC), and integrated bias generation and timing control for self-sequencing and programmability.
The output from the APS is processed to compute the centroids of the pinhole Sun images, allowing for the calculation of the Sun angle relative to a coordinate system fixed to the sensor unit. This design leverages MEMS and APS technologies to create a sensor that is at least an order of magnitude smaller and lighter than traditional digital sun sensors, while also being more power-efficient.
The motivation behind this development was to improve the capabilities of sun sensors for future space missions, where size and weight constraints are critical. The micro Sun sensor's design allows it to function effectively in determining the pointing direction towards the Sun or for position determination, which is essential for the navigation and operation of spacecraft and rovers.
The document also includes acknowledgments of the inventors involved in the project, including Youngsam Bae, Carl C. Liebe, Sohrab Mobasser, Jeffrey R. Schroeder, and Chris J. Wrigley, and emphasizes that the work was conducted under NASA's sponsorship. Overall, this micro Sun sensor represents a significant advancement in space technology, promising to enhance the performance and capabilities of future space exploration missions.
