exciting satellite kit that will help
motivate America’s next generation
of aerospace engineers.
The concept of stacking PCBs
(printed circuit boards) to form the
layers of a CubeSat was pretty simple
to grasp. Therefore, the issue I
actually struggled with the most was
the airframe of the CubeSat. I was
flummoxed to come up with a simple
and inexpensive solution, and was at
the point of asking a friend to laser-cut sheets of acrylic plastic. Using
laser-cut panels would raise the cost
of the Model CubeSat kit, so I was
hesitant to go this route. Then, one
afternoon the solution found me.
I occasionally visit the Interstate
Plastic store in Boise, ID to look over
their scraps for ideas. One day while
rummaging through their scrap pile, I
found a discounted item: a plastic
display cube for baseballs.
The cube slides open into two
pieces, with each piece being a “C”
shaped sheet of plastic. The sturdy
walls of the baseball display are 1/8”
thick, and it’s a perfectly square cube
that measured 4-3/32” across. That’s
close enough for a CubeSat model,
and I’d be able to stack my fake
PC104 cards inside of it.
Making Printed
Circuit Cards
Now that I had a cube, it was
time to make printed circuit boards
for the electronics. Before I could
design PCBs for the CubeSat, I
needed to select a microcontroller
and design its bus. A real PC104 card
supports pretty sophisticated
microcontrollers and single-board
computers (SBCs), and uses a 104-
pin bus. I had no intention of doing
the same because I was creating a
CubeSat kit for a PICAXE
microcontroller.
A PICAXE-14M2 or 18M2 would
suit the purposes of the kit since they
was programmed in BASIC. Using
BASIC meant the Model CubeSat
would have a shallower learning
curve than would using something
like C#. Since the microcontroller
would be a PICAXE, I decided to use
an 18-pin bus contained on a 2 x 18
pin SIP (two rows of the same pins)
for stability and strength.
Below are the pin functions of
the bus. If the PICAXE-14M2 is used,
APPROACHING THE FINAL FRONTIER
August 2015 71
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By modifying the Model CubeSat's generic plane, I can create
new planes with novel features that are guaranteed to stack with
the rest of the CubeSat planes.
For this microcontroller plane, I started out with the generic
plane and added the components for supporting a
PICAXE-14M2 and I2C memory.
