Implementing GNSS-Reflectometry in Space on the TechDemoSat-1 Mission

M. Unwin, S. Duncan, P. Jales, P. Blunt, J. Tye

Abstract:	TechDemoSat-1 (TDS-1) is SSTL’s latest technology demonstration mission, hosting cutting-edge UK payloads including the SGR-ReSI, the company’s most advanced Global Navigation Satellite System (GNSS) Reflectometry (GNSS-R) remote sensing instrument. GNSS-R is the measurement of GNSS signals reflected off the Earth’s surface. These signals should contain the geophysical imprint of the Earth’s surface, be it the ocean, land or ice. The primary target of SSTL and its partner, the National Oceanographic Centre (NOC), is the use of GNSS-R to determine ocean roughness, wind speed and wind direction. Potential applications for ocean surface GNSS-R include weather forecasting, climate change modelling, and logistical planning in the offshore energy and shipping industries. This paper gives an overview of the reflectometry algorithms used on the SGR-ReSI, the interfacing and the methods of testing, and the configuration of the experiment on TDS-1. TDS-1 was successfully launched on a Soyuz-2 launcher on 8th July 2014. This paper describes the early operations and results from the SGR-ReSI on TDS-1, showing the successful acquisition of both raw data and Delay Doppler Maps over Atlantic and Pacific Oceans. A campaign is being planned with support from ESA to allow the cross-correlation with buoys over a wide range of sea state conditions, with the intention of demonstrating an ocean wind measurement service. The SGR-ReSI has minimal impact upon spacecraft system design, being compact, low power and with a low data rate output. It is therefore ideally suited for use on flights of opportunity as they arise in SSTL’s own missions and for constellations of small, low-cost spacecraft. The SGR-ReSI will be flying as the primary payload on CYGNSS hurricane-sensing constellation, funded under NASA’s Earth Venture 2 programme.
Published in:	Proceedings of the 27th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2014) September 8 - 12, 2014 Tampa Convention Center Tampa, Florida
Pages:	1222 - 1235
Cite this article:	Unwin, M., Duncan, S., Jales, P., Blunt, P., Tye, J., "Implementing GNSS-Reflectometry in Space on the TechDemoSat-1 Mission," Proceedings of the 27th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2014), Tampa, Florida, September 2014, pp. 1222-1235.
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