SA's second satellite SumbandilaSat is limping along through space, says the Department of Science and Technology (DST).
However, Val Munsami, deputy director-general (DDG) for research development and innovation at the DST, says engineers working on the satellite have found an innovative way of dealing with the problem.
At a Parliamentary portfolio committee meeting this week, Munsami said the satellite is still producing images. “The satellite is still functioning but it's limping.”
Stabilisation fail
The DDG said there is a problem with the stabilisation of the satellite. He explained that when a satellite is launched, it keeps falling towards the earth but doesn't quite reach so it goes around in an orbit.
“To take a satellite image the satellite has to be pointing towards the earth all the time. If you put something in space and you don't control it, it tends to tumble and you don't want that, you want the satellite to remain as stable as possible so it points towards the earth.”
He added that the satellite tumbles in one direction but the way it is stabilised is that there are reaction wheels that spin in the opposite direction and so it pulls the satellite in the right direction.
The problem with the SumbandilaSat is that some of the reaction wheels have been lost. It has three sets of wheels, which have been labelled X, Y and Z.
“What has essentially happened in SumbandilaSat is that the Z reaction wheels have packed up so it's tumbling in the Z direction.”
Unique solution
However, Munsami said the engineers have coupled the X and Y wheels in such a way that they compensate for the Z direction.
“So the satellite tumbles but as it comes over the point where it wants to take the imagery, they slow the tumbling down. So it tumbles, it takes an image and then it carries on tumbling.”
The DDG said this is the first time such a correctional measure has been used. “It's very innovative and we get our two images per day.”
Costly faults
Munsami said SumbandilaSat is not meant to be a full flight model, but only a technology demonstrator so the limitations are expected.
He added that the satellite is cheap, having cost R26 million. Most satellites have dual redundancy where there are backup parts, but the SumbandilaSat does not have this.
However, Munsami said the problems with the satellite have not been critical so dual redundancy was not really needed.
Democratic Alliance (DA) shadow minister of science and technology Marian Shinn says the SumbandilaSat programme cost the public R90 million.
“If it cost R26 million to build and R12 million to launch, this means that about R52 million has been spent on commissioning costs and trying to correct damage caused during the launch.”
Problematic acquisition
It is partly due to these ongoing problems with the satellite that Shinn says government should not invest in SunSpace, the company that developed SumbandilaSat.
Microsatellite company SunSpace will lean on government to fill its order books, at an estimated cost of R100 million.
Cabinet recently approved a controversial majority equity stake acquisition in SunSpace of between 55% and 60% by government.
SunSpace told the DA it could not survive without a major investor assuring long-term financial stability and it had been unable to secure private industry funding.
Shinn says public money should not be invested in a satellite manufacturing company that has been unable to deliver a robust working vehicle.
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