SumbandilaSat to be commissioned soon

SumbandilaSat to be commissioned soon


South Africa: In about three weeks, South Africa’s R26-million Sumbandila Microsatellite (SumbandilaSat) will be handed over by its manufacturer, Sun Space & Information Systems (SunSpace) to the Satellite Applications Centre (SAC) of the Council for Scientific and Industrial Research.

“We’ve done an initial handover to SAC, but in parallel, we are also completing some outstanding commissioning tests,” SunSpace Chief Systems Engineer Jan-Albert Koekemoer told Engineering News Online. “We are doing so over the Internet – using a special link set up between the University of Stellenbosch and the SAC.” SunSpace is based in Stellenbosch and the SAC is located at Hartebeeshoek, west of Pretoria.

The SAC will operate the spacecraft on behalf of its custodian, the Department of Science and Technology. “I expect the outstanding items to be completed within the next couple of weeks, after which the SAC will take full responsibility for the day-to-day operation of the satellite and SunSpace will act in a supporting capacity,” he added.

“We experienced some problems during the commissioning. There were some radiation-induced anomalies,” he said. Two of the three reaction wheels (for maneuvering, SumbandilaSat has magnetic torquer rods, three reaction wheels, and a propulsion system with a small thruster), namely the Z-axis and the Y-axis wheels, cannot be used anymore, probably owing to a power distribution system failure. The result is that the spacecraft can now only be rolled only ± 5° from the nadir position (at nadir, SumbandilaSat is pointing straight down).

Nevertheless, the microsatellite can still take high resolution images because of “very innovative updates” of the algorithms in the attitude determination and control system software.

The microsatellite’s main payload is a multispectral imager, which was designed to operate across six spectral bands. This imager has a resolution of 6,25 m x 6,25 m. It was also designed, developed, and made by SunSpace. The focal plane at the back of the imager has three sensors on it – two line charge coupled devices (CCDs) with three spectral bands a sensor, and one matrix sensor, which works independently from the line sensors.

Unfortunately, the abovementioned power distribution systems failure has meant that SumbandilaSat mission control has lost access to one of the two CCD control boards, meaning that imagery can no longer be obtained from one of the CCDs. The CCD that has been lost covered the green, xantrophyll and blue spectral bands. The remaining CCD covers the more important red, red-edge and near-infrared spectral bands. As a result, the spacecraft continues to transmit useful imagery, and it also carries a lower resolution video camera.

Source: Engineering News