rover robot project I built five years ago. It uses a PICAXE-
08M2 to interface a PC to its XBee radio.
Communication with the PC is through the Terminal
program included in the PICAXE Program Editor. This
means the ground station’s PICAXE coordinates and
formats communicate between the radio and PC so that
an operator can easily understand what information the
Model CubeSat is telemetering.
The Model CubeSat is still a work in progress. In the
near term, however, I want to develop the following
First, the Model CubeSat needs more I/O in order to
take advantage of its volume. I’ve already designed the
PCB for a PICAXE-18M2 microcontroller plane; I just need
to design additional PCBs before I can send it out for
manufacture (I prefer to combine several different PCBs
and then panelize them in order to save money).
Second, the Model CubeSat needs a communications
protocol. I designed one for my moon rover and plan to
use a variation of it for the Model CubeSat. That would
allow the CubeSat to store and download data like real
CubeSats do when they’re out of range of a ground
I want additional science and engineering planes. That
way, the Model CubeSat can be restacked and
reconfigured for new missions. The latest plane I’ve
designed is a sun sensor and magnetometer plane. It
detects which surface of the CubeSat faces the Sun and
the orientation of Earth’s magnetic field relative to the
CubeSat. This will permit the Model CubeSat to determine
its attitude in space.
Another plane I’d like to create is a Geiger counter
plane to allow the CubeSat to determine the amount of
radiation around it.
What does a CubeSat do with attitude information?
Aside from transmitting that information to the ground
station, it can be used to help hold the attitude of the
CubeSat with magnetorquers. That’s not really practical
with this model, but I will create a plane to simulate
In place of magnetorquers will be bi-colored LEDs that
illuminate when the magnetorquers are energized. So,
when the Model CubeSat is out of its desired orientation,
the LEDs turn on indicating the magnetorquers are active.
The color of the LEDs will indicate the polarity of the
magnetorquers. Then, when the Model CubeSat is turned
back to its desired attitude, the LEDs are turned off.
A more difficult addition, I think, is using real solar
panels to recharge the CubeSat’s battery. The solar
panels would measure 4” square and would need to be
encapsulated for durability. The panels would
mechanically attach to the Model CubeSat airframe and
electrically connect to their own plane. The solar panel’s
current would then feed into the Vin pin of the Model
CubeSat bus. The recharging circuit would need to be an
upgraded power plane.
Finally, I want to add a camera. A slow scan camera
would be ideal, but even a baby monitoring camera
would be fine. The Model CubeSat would activate the
camera when commanded to do so by the ground
station. I’m assuming I’ll use different transmitters and
frequencies for the camera and XBee. Therefore, while
the camera is transmitting an image, there would be no
further communication over the XBee in order to
simulate the CubeSat using the same radio for both
When I think about it, I guess I’m only half way done
with just the design of the Model CubeSat. There’s still a
lot of work developing new planes, writing code, and
writing directions for students. However, it’s my hope to
make this kit available to schools as a complete
curriculum that teaches electronics, programming, and
engineering. With space as its focus, I think many
students will find it a motivating project to work on.
Onwards and Upwards,
Your near space guide NV
74 August 2015