VELOX-CI – A Tropical Microsatellite for Radio Occultation Experiment

Yung-Fu Tsai and Kay-Soon Low

Abstract:	The feasibility of atmospheric sounding using GPS radio occultation technique was first demonstrated in the GPS/MET experiment. It obtains the quantities of atmosphere based on the refractivity along the radio signal path, which means the information on the vertical profile of temperature, pressure, and humidity in the neutral atmosphere and electron density in the ionosphere can be yielded by receiving and analyzing occulted GPS signals. Owing to the success of the first microsatellite X-SAT program, NTU is collaborating with DSO National Laboratories to develop a follow-on microsatellite with a tropical environmental monitoring mission, VELOX-CI. The scope of VEXLOX-CI mission is to develop a 3D atmospheric measurement payload, hybrid attitude determination system with GPS measurement, and real-time star tracker algorithm for attitude determination. Since space-based radio occultation, the occulted signal received by a low earth orbit (LEO) satellite, has a substantial advantage over other systems due to its high vertical resolution, large spatial coverage, and an all-weather capability. VELOX-CI microsatellite would carry a GPS receiver payload to perform radio occultation for atmospheric sounding purpose. Moreover, VELOX-CI is scheduled to be launched into a near equatorial orbit, which means it has the advantage of a high revisit rate over Singapore. Thus this leads to significantly more radio occultation observability in the tropics. The concept of VELOX-CI program and the radio occultation payload would be presented. A preliminary analysis has been conducted for the satellite tropical orbit based on the onboard GPS antenna configuration and some unique features of the design would be highlighted.
Published in:	Proceedings of the ION 2015 Pacific PNT Meeting April 20 - 23, 2015 Marriott Waikiki Beach Resort & Spa Honolulu, Hawaii
Pages:	542 - 547
Cite this article:	Tsai, Yung-Fu, Low, Kay-Soon, "VELOX-CI – A Tropical Microsatellite for Radio Occultation Experiment," Proceedings of the ION 2015 Pacific PNT Meeting, Honolulu, Hawaii, April 2015, pp. 542-547.
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