Cape Town - It’s 10cm wide, 10cm long, 55mm high and worth R100 000.
And this time next month, the Attitude Determination and Control Subsystem (ACDS) – the culmination of multiple Stellenbosch masters projects and two years of development – will be in space.
It’s part of a project called QB50, which is aiming to put 50 CubeSats or miniature satellites into orbit in 2016.
The project is a collaboration of universities and space companies from around the world, headed by the Von Karman Institute of Fluid Dynamics in Brussels, and the ACDS developed by Stellenbosch University’s Electronic Systems Laboratory will be up there, representing Africa.
A single unit of the CubeSat is small and relatively cheap – 10cm cubed in size weighing 1kg and made of commercial, off-the-shelf components. But the QB50 satellites will be different.
Instead, a science unit will be mounted on one end, leaving a double-unit CubeSat “like a shoebox”, explained Professor Herman Steyn.
They’ll be deployed in the lower thermosphere, starting out at about 380km and descending over nine months to about 200km, due to drag.
“The idea is to take measurements of the upper layers of the atmosphere,” Steyn said. “What does it contain? What are its density levels? This will help scientists accurately predict what happens to an object which re-enters the atmosphere and how it will burn up.”
The university’s ACDS will stabilise this ever-falling shoebox, keeping the science unit pointing to within 10 degrees of its flight direction.
The key is a small disc powered by an electronic motor. As the disc spins, the satellite gets what’s called gyroscopic stiffness, like the stability of a fast-turning spinning top.
Like many of the of the components on the ACDS, this was the work of Maties masters student Jako Gerber, who designed it as an undergraduate.
Stellenbosch was commissioned to build 15 of these units for the QB50 project. With the income from the unit sales – R100 000 each – the university will be contributing a satellite of its own to the project, the ZA-AeroSat.
Mike-Alec Kearney, a former student working as an engineer in the research group managing the project, said the team would use the satellite’s antennas as another stabilisation method, “like the feathers on a dart”.
Some ACDS software will be provided by the Surrey Space Centre in the UK, while students from the Cape Peninsula University of Technology are working on the satellite’s communication module.
The project launch isn’t until January 2016 but the first two satellites will be in the low-Earth orbit as early as next month as part of the QB50 precursor test flight. The Stellenbosch equipment will be on board. - Weekend Argus