South Africa’s first Cubesat, ZACube-1, is set to be launched into space from Kazakhstan before the end of the year. A Cubesat is a nano satellite, a standardised format developed in the US, with dimensions of 10 cm × 10 cm × 10 cm. (Although there are now also some bigger Cubesats, 20 cm or even 30 cm high, but still with lengths and widths of 10 cm.) ZACube-1 has been developed at the Cape Peninsula University of Technology (CPUT) under the auspices of the French South African Institute of Technology (F’SATI). “It’s South Africa’s third satellite and first Cubesat,” pointed out F’SATI Space and CPUT Department of Electrical Engineering junior engineer Etnard Louw. “We’re very proud of that.”
“It’s currently in the Netherlands, undergoing pre-integration work,” he reported. Because they are so small, Cubesats are usually placed in groups of three in special pods, which are then mounted on the launch vehicle. ZACube-1 is going to be launched with two other Cubesats from other countries. All three tiny spacecraft have to be loaded into the pod and then subject to preflight tests. The pod is then shipped to the launch site and integrated on the launch craft.
Although tiny, ZACube-1 has a serious mis-sion. It is fitted with a high frequency radio beacon which will be used to characterise the South African National Space Agency’s new SuperDARN radar which will soon be installed at South Africa’s Sanae Antarctic research base. Although the Cubesat’s tiny on board computer (OBC) is a commercial system that was bought by the F’SATI/CPUT team, most of the systems on the nano satellite were developed by the local engineers, including the communications system. In addition, the software for the OBC was developed by the Cape Town team.
“The hoped-for life is two years,” stated Louw. “Anything longer than that would be a bonus. But it always depends on the sun’s activity.” Greater solar activity could fry the nanosatellite’s systems and kill it. Lesser soar activity could extend its life.
In parallel, to stimulate the interest of school- children in space science and technology, CPUT and F’SATI Space last year started to make use of Cansats. These are given this name because they contain all the basic elements of a real satellite within a body the size and shape (and often converted from) a soft drink can.
“There are international Cansat competi-tions,” reported Louw. “We decided to adopt the concept. We call ours AfriCansats. They are intended to stimulate children’s interest in space and space technology.” CPUT has undertaken a number of Cansat outreach missions to schools in its region, and already one group of schools has incorporated Cansats into their curriculum. “Cansats are a fun thing. They take the essence of space [engineering] and put it in a fun form.”
A Cansat contains all the essential sub-systems of a real satellite. It has a power source – usually a cellphone battery. It has a simple control board, equivalent to a real satellite’s onboard computer. It carries an experiment, often in the form of a weather board incorporating a temperature sensor and a barometric pressure sensor. It has a satellite navigation (GPS) module and a transmitter to send the data gathered by its sensors. Finally, there is a (also very small) ground station.
Of course, a Cansat is not a satellite at all – they do not (and are not designed to) go in to orbit. But they do fly. Standard practice, followed by CPUT, is to suspend a Cansat below a helium-filled balloon. When the mission is finished, a command from the ground station activates a simple device which severs the Cansat from the balloon. As it falls under gravity, the Cansat pulls the parachute out of a bag and so parachutes safely to the ground. So Cansats even simulate the return of spacecraft to earth.