P O Box 90438
Garsfontein 0042
South Africa
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KLETSKOUS CubeSat Project  

Hannes Coetzee, ZS6BZP, B.Eng. Electronic (Pretoria), M.Sc. Space Physics (Rhodes)

 SA AMSAT has decided to embark on the development and launching of a South African Amateur satellite. The satellite will be based on the CubeSat principle. The subject of this paper will be a basic satellite with a short time to launch.

 Mission (Purpose) of the CubeSat 

While radio amateurs all over the world raved about SumbandilaSat, local Hams missed out as the vast majority of Southern African passes were used to download images, the primary mission of SumbandilaSat. It can thus be argued that SumbandilaSat did not fulfil its secondary mission of education and creating an interest in science, technology, engineering, mathematics and space in Southern Africa. 

The mission of the new satellite is to give radio amateurs (and educational institutions) in Southern Africa easy access to a Low Earth Orbit (LEO) satellite on as many of the available passes as possible and thus stimulate interest and activity in space, satellites and amateur radio. A secondary mission is to fly a scientific payload proposed and designed by an educational institute in South Africa. This will further increase the participation of the youth in the project, helping to create interest in science and technology.  

The development phase of the CubeSat is currently known as (Project) KLETSKOUS. This reflects nicely on the mission and functionality of the satellite: “Klets” is an Afrikaans word for talking a lot. We want the Southern African radio amateurs to talk and operate much more via satellite. “Kous” is the Afrikaans word for a sock. The transponder that is planned for the satellite can also be referred to as a “bent-pipe” transponder, aligning the idea to the “sock”. 

Once the satellite nears completion a competition may be run to decide on an applicable name for the satellite, as was the case for SumbandilaSat. On the other hand it seems as if most people have grown fond of the project name and the satellite may end up being referred to as KO xx, indicating KLETSKOUS OSCAR xx. 


While it is considered that a 2 m uplink and 70 cm downlink is desirable from a user perspective, the International Radio Union (IRU) advises that 2 metre uplinks are problematic as in many parts of the world there are too many illegal, non-amateur transmissions. The satellite may receive these transmissions and make matters worse by re-broadcasting it on 70 cm.  

Given that most hand-held transceivers sold today are both 70 cm and 2 m capable, the problem of non availability of 70 cm transmitting equipment will fall away and KLETSKOUS should be as easy and convenient to work as what SumbandilaSat was. 

For KLETSKOUS the uplink is on 70 cm, and the downlink on 2 m. A linear transponder with a bandwidth of 20 kHz is utilised for both FM and SSB. A sub-carrier for a telemetry downlink will be included. For command and control purposes a separate 70 cm frequency will be used. Currently frequencies in the 435.100 to 435.140 MHz range are considered for the uplink and 145.860 to 145.980 MHz for the downlink. The above architecture will ensure that the transponder is accessible for general use while the satellite is being commanded and controlled by the ground station. Maximum access by Southern African Hams to KLETSKOUS is thus ensured. 

The development of the transponder has progressed to the point where the second prototype is now ready for on the air tests. The output power is at the required level (≥ 200 mWatt) and the gain of the RF path has also been increased to the amount required. The transponder will be integrated with the On Board Controller (OBC) after completion of the RF tests. The command link and telemetry downlink will then also be addressed. Lessons learned and updates that may be required will then be implemented on a next prototype.   

Scientific Payload  

KLETSKOUS will also carry a scientific payload designed and developed by an educational institute (school) and it will probably be in the form of a magnetic sensor.  

Worm holes are portals joining two distant parts of space, a sort of shortcut through space and time. However the question is are they real or just science fiction?  

Theoretically worm holes are places where the magnetic field of Earth connects to the magnetic field of the Sun, creating an uninterrupted path leading from our own planet to the sun's atmosphere 93 million miles away.  Finding these portals should be relatively easy; furthermore studying these portals would provide us with much information on these cosmic mysteries.


The aims and objectives of the Worm Hole project are as follows: 

  • Find portals between the sun and the Earth’s magnetic fields by comparing predicted and measured magnetic field strengths.
  • Send abnormal current and voltage readings back to Earth for further analyses to try and prove the existence of worm holes.

Implementing this project may be challenging as KLETSKOUS is going to make use of passive magnetic stabilization that may interfere with the scientific experiment.  

The project was proposed by the Laudium Secondary School Meet Trivedi.

Design Philosophy 

KLETSKOUS will be a 1U CubeSat. The dimensions are 10 cm x 10 cm x 10 cm. The total volume of the satellite is 1 litre and the maximum weight 1.1 kg. This is indeed very compact. In order to achieve a realistic launch schedule some of the subsystems of the CubeSat will have to be bought from overseas suppliers.

Space Frame 

Deon Coetzee is achieving the unimaginable by crafting space frames in his home work shop. The first two prototypes were very impressive. The University of Stellenbosch has come on-board and the optimization of the space frame is now a project addressed by a final year mechanical engineering student, Francois Oberholzer. 

Deon is also developing the mounting and deployment mechanism for the antennas as well as investigating multiple solar panels on KLETSKOUS.  







House Keeping 

A Command Link will be required for housekeeping purposes and also maybe in-flight reprogramming of the onboard controller, although this is risky business as the satellite may be killed if the reprogramming is unsuccessful. The best option would be to launch the satellite with flawless software already loaded, if at all possible. 

A Scheduler will switch the transponder on and off at pre-determined times that will correlate to certain areas being over flown by the satellite. It will be possible to set the onboard clock of the Controller to ensure that the Scheduler performs correctly. 

A Telemetry Downlink will be required. Some of the parameters that must be monitored on the ground include battery voltage and temperatures, orientation of the satellite via the radiation sensors in the centres of the five solar panels and the output voltages of the solar panels. It is planned that the Command and Telemetry functions be based on those implemented on the High Altitude Balloon Experiment, HABEX. 

The first prototype On Board Controller (OBC) has been completed and the house keeping software is currently being developed and tested by Brian McKenzie. 

Power Budget  

Johan, ZR1BMD working for ISIS in the Netherlands gave the following information: A Typical 1U CubeSat will have 12 solar cells (2 each on the 6 facets of the cube). When stabilised by a passive magnetic system the solar panels will have a typical efficiency of about 28% at the start of their lives and for a typical orbit will have 2.7 W "orbit average" and 3.6 W "sunlit average" power available. After some time in space the efficiency will fall to about 21% and the available power budget will decrease to 2 W and 2.7 W respectively. (That is not much to play with!) The final values will be very dependent on the orbit selected.

We are very fortunate that Denel Dynamics have provided KLETSKOUS with three prototype solar panels on a long term loan agreement. These solar panels have been characterised and the data obtained is now being used by Fritz Sutherland jnr. to develop the power supply for KLETSKOUS. The EPP is an advanced design that ensures optimum utilization of the power supplied by the solar panels. During flight all the electronics, especially the Transponder must be powered with any surplus power being used to charge the batteries.  When the batteries eventually fail the satellite should be able to function when it is lit by sunlight.

With this amount of power available the maximum RF output of the satellite cannot exceed 0.5 W. In general the output power will have to be reduced to 200 mW or less. Experience with other Low Earth Orbit (LEO) satellites; including SumbandilaSat have indicated that successful communications with a modest ground station is not a problem at this power level. 


 It will be difficult to implement active stabilisation in a 1U package together with the transceivers required for the main payload. A passive (magnetic) stabiliser should keep the antennas adequately orientated during a pass over Southern Africa. This is also the solution implemented on FunCube.