Vid The CleanSpace One Project is going to deploy a conical net on its orbital dustpan ship to capture a small SwissCube satellite, which had been purposefully littered into orbit as a demonstration of a interstellar debris collection.
A 10cm3 satelliting box has been zipping about Earth's atmosphere for over five years, with nothing to do but wait for astroboffins to snatch it up.
The box was always intended to be cleaned up, but the challenge was figuring out a way to do it.
Engineers from eSpace, École polytechnique fédérale de Lausanne's Center for Space Engineering and Signal Processing 5 Laboratory (LTS 5), and partners from University of Applied Science in Geneva (HES-SO HEPIA), were seemingly confident they could meet this challenge.
For the past three years, they've been working on the space sweeping satellite that will be sent into orbit to recapture SwissCube. It will trap the box and then, in a Gandalf versus Balrog fall of death, the two will combust in the atmosphere.
"SwissCube is not only a 10cm by 10cm object that's tough to grasp, but it also has darker and lighter parts that reflect sunlight differently," explains Christophe Paccolat, a PhD student working in LTS 5. "These variations can perturb the visual approach system and thus also the estimates of its speed and distance."
Muriel Richard-Noca, head of the project, emphasises the extreme delicacy of the mission: "It only takes one error in the calculation of the approach for SwissCube to bounce off CleanSpace One and rocket out into space."
To avoid such a cock-up, the visual approach algorithms on the cleanup satellite's cameras are currently being tested. They will need to take into account a variety of parameters, such as the angle of illumination of the Sun, and all the uncertainties involved in this measurement.
To design the most efficient capture system, the engineers benefited from the collaboration of microengineering students from HES-SO HEPIA. The engineers finally opted for the so-called "Pac-Man" solution, although the machine looks nothing like the pill-popping arcade beastie.
The prototype resembles a net in the form of a cone that unfolds and then closes back down once it has captured the small satellite.
"This system is more reliable and offers a larger margin for maneuvering than a claw or an articulated hand," said Michel Lauria, professor of industrial technology at HEPIA.
CleanSpace One could be launched as early as 2018 in collaboration with the company S3, headquartered in Payerne. The development of the approach and capture systems has passed the prototype stage, which involved making critical choices for the project.
The next stage will combine putting together the first version of the engineering models – which will be more accurate than the prototypes – and more extensive tests. ®