SumbandilaSat is living up to its Venda name as it ‘leads the way’ in providing South African entities with valuable satellite imagery at no cost, despite earlier technical setbacks. During August and September 2010 SumbandilaSat acquired five high resolution images of the south-western part of the Kruger National Park and neighbouring Bushbuckridge where the CSIR and SANParks Scientific Services are conducting various research projects.
These images would have cost in excess of R40 000 each from a commercially operated satellite, but now SumbandilaSat can deliver the imagery (50 x 60 km area per image) for specific projects to local users at no cost. So far 800 images have successfully been taken of targets worldwide (of which approximately 54% are cloud-free) – this translates to four images on an average day. Three to five images can be captured of southern African targets per week.
Earlier in the mission, a setback was experienced with the performance of the attitude stabilisation system on the satellite. To counter the problem, the SunSpace design team managed to guide the satellite to tumble ‘head-over-heels’ to scan an image from south to north, whilst orbiting north to south. This unique and initially unplanned manoeuvre allows the satellite to continue to take high resolution images of worldwide targets on a daily basis.
The provision of free and frequent high resolution satellite images of specific areas of interest will revolutionise earth observation in many fields, so that natural events (e.g. fire), natural disasters (e.g. floods) and human activities (e.g. mining, settlements, forestry) can be accurately monitored on a regular basis.
The SumbandilaSat images can also be used to map burnt areas, for example, in the Kruger National Park where fire is part of the natural ecology and is used as a management tool by SANParks to manipulate the vegetation to promote biodiversity and influence the balance between grass, shrubs and big trees.
The experimental burn plots shown in the SumbandilaSat image are part of a long-term fire experiment that was set up in and maintained since 1954. The initial objective for this experiment was to investigate and understand the effects of fire frequency (e.g. annually, biennially or every third year) and season of fire (early summer - December, late summer - February, autumn - April, winter - August and after spring rains - October) on the vegetation, e.g. tree, grass and shrub density and height.
The SumbandilaSat image clearly shows how the natural fire was excluded from the experimental burn plots, while specific blocks within the plots were burned in August 2010 by SANParks as part of the experiment. After 56 years this valuable experiment is considered a comprehensive scientific trial for understanding the influence of fire on bush encroachment, grazing quality and other fire and herbivore interactions. The satellite imagery can also be used to monitor the recovery of the vegetation in the burnt area and the long-term influence of fire on tree and grass cover.
SANParks currently has to rely on very coarse resolution satellite images with 500m pixel size for regular mapping of burnt areas. SumbandilaSat provides images at 6.25m pixel resolution and covers a 50x60km km area per image.
Although the imaging capacity of SumbandilaSat is much less than that of commercial high resolution satellites, the satellite has demonstrated the viability of affordable micro-satellite technology, which is its primary stated mission. A constellation of similar satellites is planned to increase the availability of such satellite data for diverse applications. Several African countries will participate in this joint venture and will eventually share in the data produced by the African Resource Management Constellation, especially for disaster monitoring applications.
The South African National Space Agency (SANSA) will be tasked with ensuring that society benefits from investments in space-based earth observation technology in accordance with our national Space Strategy.
SumbandilaSat images are available via the CSIR Satellite Applications Centre catalogue (http://catalogue.sac.co.za, ‘search’ Sumbandilasat MSS). New image requests can be directed to sales and customer services at the CSIR Satellite Applications Centre.
