New robotic tracking system to be used to help repair orbiting satellites

Washington, Oct 3 : Researchers at Queen's University, Canada, are developing a new robotic tracking system that will be used to enable repairs of orbiting satellites.

This system will service more than 8,000 satellites now orbiting the Earth, beyond the flight range of ground-based repair operations.

Currently, when the high-flying celestial objects malfunction - or simply run out of fuel - they become "space junk" cluttering the cosmos.

"These are mechanical systems, which means that eventually they will fail," said Electrical and Computer Engineering professor Michael Greenspan, who leads the Queen's project.

But, because they are many thousands of kilometers away, the satellites are beyond the reach of an expensive, manned spaced flight, while Earth-based telerobotic repair isn't possible in real time.

Dr. Greenspan's solution to this problem is the development of tracking software that will enable an Autonomous Space Servicing Vehicle (ASSV) to grasp the ailing satellite from its orbit and draw it into the repair vehicle's bay.

Once there, remote control from the ground station can be used for the repair, he explained.

"The repair itself doesn't have to be done in real time, since everything is in a fixed position and a human can interact with it telerobotically to do whatever is required," he said.

The Queen's team is now working to develop the ASSV with the aerospace company MDA (McDonald-Detweiller Associates) Space Missions, which earlier built the Canadarm and has been responsible for all Canadian systems in the International Space Station.

According to Dr. Greenspan, computer vision is the main technical challenge of grasping the satellites.

Since these objects circle the globe in "geosynchronous" orbit, their speed is synchronized with the Earth's rotation.

The robotic system must recognize the satellite first, then determine its motion and match that motion before grabbing it.

Due to the harsh illumination conditions in space, conventional video cameras are of limited use.

The preferred sensor is a form of light-based radar called LIDAR, which provides a set of 3D points that accurately measure the surface geometry of the satellite.

The Queen's team, which includes Electrical and Computer Engineering graduate students Limin Shang, Babak Taati and Michael Belshaw, has developed a software that allows such a system to identify a satellite, determine its position and finally track it in real time, using this specialized range data.

ANI