Session

Session V: Advanced Technologies 1

SSC09-VI-8.pdf (1419 kB)
Presentation Slides

Abstract

This paper describes the X-Band Antenna Pointing Mechanism to be used for the first time as part of the Payload Downlink Chain on-board the SSTL-300 platform for the upcoming NigeriaSAT-2 mission, due for launch late in 2009 . NigeriaSAT-2 is a high performance Earth Observation mission designed for a 7.5 year lifetime to achieve 2.5m imagery in a panchromatic waveband along with 5m and 32m imagery in four mutli-spectral channels. The spacecraft will deliver high data throughput on an agile platform, whilst still maintaining high levels of pointing accuracy during downlink opportunities. All of this will be included in a 300Kg satellite. The innovative Antenna Pointing Mechanism developed by Surrey Satellite Technology Limited incorporates a compact circularly polarized antenna with a narrow 3dB beam-width of 25degrees and bore-sight gain of 15dBiC. It also houses the necessary drive electronics and structural elements to provide a nimble, 2-axis antenna solution. The pointing accuracy of the unit is better than 1 degree and the maximum slew rate is better than 20deg/s, at acceleration rates up to 4deg/s/s. Such low-cost and compact yet agile antenna systems have not been used previously on small satellite missions and as such, the Antenna Pointing Mechanism is an enabling technology in the commercialization of small Earth Observation spacecraft missions. Numerous design trades were made along the development path of the Antenna Pointing Mechanism and these are covered in this paper. Additionally a treatment of the use of polarization diversity on the NigeriaSAT-2 mission as a way of doubling the data throughput capability is reported.

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Aug 11th, 3:45 PM

Follow that Ground Station! And Double the Data Throughput using Polarization Diversity

This paper describes the X-Band Antenna Pointing Mechanism to be used for the first time as part of the Payload Downlink Chain on-board the SSTL-300 platform for the upcoming NigeriaSAT-2 mission, due for launch late in 2009 . NigeriaSAT-2 is a high performance Earth Observation mission designed for a 7.5 year lifetime to achieve 2.5m imagery in a panchromatic waveband along with 5m and 32m imagery in four mutli-spectral channels. The spacecraft will deliver high data throughput on an agile platform, whilst still maintaining high levels of pointing accuracy during downlink opportunities. All of this will be included in a 300Kg satellite. The innovative Antenna Pointing Mechanism developed by Surrey Satellite Technology Limited incorporates a compact circularly polarized antenna with a narrow 3dB beam-width of 25degrees and bore-sight gain of 15dBiC. It also houses the necessary drive electronics and structural elements to provide a nimble, 2-axis antenna solution. The pointing accuracy of the unit is better than 1 degree and the maximum slew rate is better than 20deg/s, at acceleration rates up to 4deg/s/s. Such low-cost and compact yet agile antenna systems have not been used previously on small satellite missions and as such, the Antenna Pointing Mechanism is an enabling technology in the commercialization of small Earth Observation spacecraft missions. Numerous design trades were made along the development path of the Antenna Pointing Mechanism and these are covered in this paper. Additionally a treatment of the use of polarization diversity on the NigeriaSAT-2 mission as a way of doubling the data throughput capability is reported.