KLETSKOUS CubeSat Project
AMSAT embarked on the development and launching of a South African
Amateur satellite. The satellite is based on the CubeSat principle.
Mission of Kletskous
radio amateurs all over the world raved about SumbandilaSat, local
radio amateurs 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
mission of Kletskous 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 scientific payloads
proposed and designed by educational institutions in South Africa.
This will further increase the participation of the youth in the
project, helping to create interest in Science, Technology,
Engineering and Mathematics (STEM).
name, KLETSKOUS reflects on the mission and functionality of the
satellite: “Klets” is an Afrikaans word for talking a lot.
Hannes Coetzee ZS6BZP , Project Manager
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”.
it is considered that a 2 m uplink and 70 cm downlink is desirable
from a user perspective, the International Radio Union (IARU)
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 these unwanted signals on 70 cm.
that most hand-held transceivers available 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.
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
Jacques Roux responsible for the transponder
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 radio amateurs to KLETSKOUS is
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.
will also carry scientific payloads designed and developed by
education institutions (schools) Schools and other interest groups
have been invited to submit proposals. The original closing date was
31 March but with school holidays it has been extended till 30 April
at a SA AMSAT Satellite and Amateur Radio workshop at the Innovation
Hub (March 2016)
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 1.3 kg. This is indeed very compact.
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
optimisation of the space frame is now a project addressed by post
graduate mechanical engineering student, Francois Oberholser.
is also developing the mounting and deployment mechanism for the
antennas as well as investigating multiple solar panels on KLETSKOUS.
Deon Coetzee ZR1DX
Command Link will be required for housekeeping purposes and also
maybe in-flight reprogramming of the on-board 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
Scheduler will switch the transponder on and off at pre-determined
times that will correlate to certain
Brian Mckenzie ZS6BMD
being over flown by the satellite. It will be possible to set the
on-board clock of the Controller to ensure that the Scheduler
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. The first prototype On Board Controller (OBC) has
been completed and the house keeping software is currently being
developed and tested by Brian McKenzie. The second generation board
is now being completed and software updated with the emphasis on
the communication lines with the other units on the CubeSat
Erasmus , 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.
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
utilisation 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
Fritz Sutherland ZS6FSJ
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.
Although the initial decision around the battery type was that
Li-Polymer batteries gave the best power-to-weight and
power-to-energy ratio for a widely used battery, the fire hazards
associated with the battery type prompted a second look at battery
types. Since many Li-Polymer batteries have been used in space
applications, the risk seemed acceptable, but there are other
(newer) types with similar weight and performance with less risk of
fire or explosion that are becoming widely available.
the decision was made to move from a Li-Polymer battery to a LiFePo4
(Lithium iron Phosphate) battery. Since the nominal voltage and
charge requirements differ slightly, the search for a new battery
charge controller began. Eventually the LT3652 was chosen, which
offers the additional bonus of having MPPT (maximum power point
tracking) on the supply.
the new battery and charge controller had been integrated on the EPS
circuit diagram, it was time to start the next version of the PCB.
The goal of this version is three-fold:
perform a functional test of the new battery and charge controller
on the EPS.
do a layout conforming to the specified PCB outlines to ensure the
board will fit correctly into the space frame. This included
specification of the PC104 inter-PCB connectors and the
pin-functions to be used on this connector.
use the board in the first system-wide test. All the PCBs that make
up the satellite system will be connected together in order to test
how the system works as a whole.
Currently the schematic and PCB layout have been completed and the
boards are being assembled and tested.
will be difficult to implement active stabilisation in a 1U package
together with the transceivers required for the main payload.
For Kletskous we are planning to use passive
magnet stabilisation. The first development board is shown below.
The board is positioned in the space frame at the centre of gravity.
Frik Woff ZS6FZ
Watch demonstration video
Passive Stabilisation of Kletskous
Frik Wolff ZS6FZ. Member of the AMSAT SA CubeSat
For any CubeSat (or any satellite for that
matter) in a low earth orbit it is important for Passive Satellite
Stabilisation using either Passive Permanent Magnets, a Gravity
gradient bias, or an aerodynamically stable design.
Read more about passive stabilisation