SA AMSAT TURNS TO INNOVATION FOR IT’S CUBESAT 

Building a CubeSat   can be an easy task if one has the budget to buy a kit of parts and simply assemble it.  SA AMSAT does not have the two million Rand so the team had to go to the drawing board and design as many of their own components as possible.

The project has been name KLETSkous (Afrikaans for Chatterbox). The final name once completed and ready for launch will be decided through a naming competition.

It is challenging task but task out of the challenge has come some very innovate solutions. The first proto-type of the space frame showed what can be done in a garage workshop if one uses ingenuity and work around complicated processes and find practical ways of achieving the same end-result as a space frame machined in sophisticated workshops overseas. Deon Coetzee, ZR1DE is now building the second prototype using special space qualified aluminium. This frame will be used for the engineering model of the satellite after which he will build the one that goes into space. Doing it yourself can present problems like the first one built form standard aluminium the corners were easy to bend, but the space qualify aluminium does not so. Deon Coetzee has to go back to the drawing board and devise another method using slide in corners. A further prototype is current being machined.

The transponder included in the payload is also of unique design and will be the first of its kind to fly on a cubesat. A cubesat is typically 10x10cx10 cm and may not have a mass of more than 1.3 kg. The transponder design is linear which means that it can handle FM and Single Side Band (SSB) signals. The uplink will be in the 70cm band with the downlink in the 2 metre band. With a bandwidth of 20 kHz, the transponder will be able to handle 2 FM channels or several SSB channels simultaneously.

The design for the transponder was done by Jacques Roux.  “I have concentrated on a design that requires minimum tuning using off-the-shelf saw filters, mimic blocks and oscillator Integrated circuits, mixers and automatic gain amplifiers. It was my objective to keep the design as simple as possible without compromising functionality.”   The first proto-type PCB are currently being populated and it is planned to demonstrate the transponder operation at the annual SA AMSAT space symposium to be held on 18 May at the Innovation Hub in Pretoria.

“We are fortunate that Trax Interconnect has come on board with the sponsorship of the manufacture of the printed circuit boards as the board are complicated and have to be of a very high standard to operate in space. The first prototype board have already been delivered.” Jacques said.

“One of the major problems radio amateurs in South Africa experienced with SumbandilaSat’s amateur payload was that the rest of the world were able to enjoy the transponder facilities on almost every pass over while when over South Africa much of the resources of the satellite were dedicated to telemetry and commanding operations,” Hannes Coetzee who is the project manager for KLETSkous said. “We will overcome this with a second telemetry and command transceiver.

“Another interesting feature designed in the transceiver is that should the battery fail, the unit can reboot itself and operate directly from the output of the solar panels.  Battery failure in space is a common problem.”

The command and control system is also at first prototype stage and is the brainchild of Brian Mackenzie.

Currently the SA AMSAT team is looking for additional team members to take control of the power system, regulator, batteries and solar panels. While these are available as complete units from several suppliers, the cost is very high. “We would have to find a sponsor to buy out the power unit and solar panels or build some of the systems locally.” Hannes said.