UniNa Micro Sun Sensor as Technology Demonstration Payload
- Paper number
IAC-06-C1.P.2.01
- Author
Dr. Giancarlo Rufino, University of Naples "Federico II", Italy
- Coauthor
Mrs. Michele Grassi, Italy
- Coauthor
Mr. Danilo Rolfi, Italy
- Year
2006
- Abstract
This paper presents a modern digital micro sun sensor (MSS) for attitude determination that is being developed at the Department of Space Science and Engineering (DISIS) of the University of Naples (Italy). The sensor has been selected as one of the technology demonstration payloads of the ASI (Italian Space Agency) first microsatellite mission, to be flown by the end of 2008. In this work, sensor development and results of on-ground tests for sensor characterization are presented. The recent evolution of micro-technology has made micro-satellites able to compete with larger satellites. Indeed, a number of scientific and technology demonstration missions based on micro-satellites have been already flown by universities and space agencies. As an example, NASA is studying the use of micro-engineered systems for interplanetary missions; Earth remote sensing missions have been proposed and carried out, and particular efforts are being done to fly high-resolution sensors on board microsatellites [1]. The ASI microsatellite mission is representative of the latter category. Its payload includes technology demonstration of advanced concepts, such as the DISIS MSS, besides high-resolution electro-optical sensors for Earth Observation. This paper deals with the design, development and calibration of an APS-based MSS. The sensor architecture (120°-field of view) is based on a 1024x1280-pixel APS detector and on a mask consisting of an array of equally-spaced tiny holes (0.1-mm radius) placed on the top of the APS (3 mm focal distance) [2,3]. Multiple measures of the sun-line direction are obtained by evaluating the sun image centre coordinates in the sensor reference frame by an effective centroiding algorithm. The device includes a dedicated CPU that controls sensor operation and autonomously switches between various operating modes, depending on platform dynamics, sensor status, and received commands. All of the system is based on COTS components, except for the mask that was specifically designed and realized. Sensor calibration, based on neural networks, .is being performed in a facility, expressly designed to this purpose, that is based on a sun simulator consisting of a 1000-Watt Xenon arc lamp, an integrating sphere and a collimating lens. The sensor is installed on a 2-axis rotation system consisting of two high-precision, single-axis rotation stages, actuated by stepper motors capable of 1-arcsec incremental motion. The whole system is assembled on an optical table and is remotely controlled. For sensor calibration function construction, a large number of sun-spot acquisitions at different pointing angles is automatically performed with an ad-hoc software. Preliminary tests have demonstrated 1-arcminute accuracy for the sensor equipped with a 1-hole mask, and interesting performance improvements for the multiple-hole configurations [4]. The complete calibration campaign results for the latter case will be presented in the paper together with a description of the sensor and test facility [1] Selected Proc. 5th Int. Symp. of IAA on “Small Satellites for Earth Observation,” Berlin (D), 2005 [2] M. Buonocore, M. Grassi, e G. Rufino, “APS-based Miniature Sun Sensor for Earth Observation Nanosatellites”, Acta Astronautica, 56, 1-2, 139-145 [3] G. Rufino, A. Perrotta, e M. Grassi, “Laboratory Test of an APS-based Sun Sensor Prototype”, Proc. ICSO 2004, Toulouse (F), 2004 [4] G. Rufino, M. Grassi, V. Pulcino, e A. Degtyarev, “A Micro Sun Sensor for Earth-Observation Nanosatellites Flying in Formation,” Proc. 5th Int. Symp. of IAA on “Small Satellites for Earth Observation,” Berlin (D), 2005
- Abstract document
- Manuscript document
IAC-06-C1.P.2.01.pdf (🔒 authorized access only).
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