Stellenbosch, South Africa
Stellenbosch, South Africa

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Van Der Merwe D.,SunSpace and Information Systems Pty Ltd. | Steyn J.,SunSpace and Information Systems Pty Ltd.
62nd International Astronautical Congress 2011, IAC 2011 | Year: 2011

This paper summarises the development of the thermal control system (TCS) of SumbandilaSat. SumbandilaSat is an earth observation satellite; designed, built and commissioned by SunSpace and Information Systems (Pty) Ltd. The TCS is discussed in terms of requirements, design constraints, mathematical simulation, thermal loads, testing and in-orbit performance. Due to design constraints, development was done mainly through mathematical simulation. In addition, no long lead-time components could be considered e.g. multi-layered insulation (MLI) heat pipes, radiators, heaters, etc. As a result only passive components were considered e.g. coatings, tapes and internal conduction paths. An overview of the application of these components is presented. Limited qualification, acceptance and thermal balance tests were performed on the flight model. The comparison of this test data with simulated data is discussed. The in-orbit performance of the TCS is discussed based on in-orbit measurements. In addition, comparison between simulated and measured in-orbit data is also discussed. Copyright ©2010 by the international Astronautical Federation. All rights reserved.


Olivier R.,Sun Space and Information Systems Pty Ltd.
62nd International Astronautical Congress 2011, IAC 2011 | Year: 2011

Private small satellite manufacturers in the developing world are not plentiful and there are good reasons for this statement. This paper will examine the reasons for the dearth of small satellite manufacturers by looking at the market structure in the small satellite industry, positioning requirements for small satellite manufacturers, market entry barriers, (un)competitive behavior, and projections for potential growth in this market segment. Copyright ©2010 by the International Astronautical Federation. All rights reserved.


Van Zyl J.,Sun Space and Information Systems Pty Ltd | Lochner J.G.,Sun Space and Information Systems Pty Ltd
Acta Astronautica | Year: 2012

Sumbandila (SO-67) is an 81 kg LEO satellite launched on 17 September 2009 Its primary payload is a multi-spectral imager with a ground sampling distance of 6.25 m at an orbit altitude of 500 km. Its two command transceivers operate in the commercial and amateur radio VHF and UHF bands and one of them provides a VHF to UHF repeater service to radio amateurs. This paper presents initial results of a global three week monitoring period of two VHF frequency ranges. The data is obtained by executing on-board flight control procedures to select the frequencies to measure. The existing on-board telemetry gathering system is employed to record the data, most notably the received signal strength for the selected frequency. The data is downloaded using an adaptation of the imagery data download path. We determine regions of high signal levels by distributing individual measurements over cells in the satellite footprint before averaging over the cells. The data is then plotted on a geographical signal strength heatmap. We compare our results with that of a similar study of the late 1990s and point out changes since then. The data provides useful information for selecting future ground station locations for minimum interference. It further gives an indication of frequencies to use for command and telemetry communication at existing ground stations. We propose that including a receiver capable of measuring frequency interference across a desired frequency range is very useful to future missions for selecting communication frequencies from this range for ground station locations. © 2012 Elsevier Ltd.

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