How to repair a satellite while it’s in orbit

Imagine spending years and hundreds of thousands of dollars on building a satellite, and then tens of thousands of dollars to send it up to space, only for it to suddenly break down hundreds of kilometres above the Earth, with no way to fix it.

This is not just a hypothetical. About 50% of cubesats (mini satellites usually launched by universities and researchers) fail.

So, researchers are trying to design what seems almost impossible – robots that can gently repair satellites while both are still in orbit.

“Satellites, when they are operating in orbit, are not like a car – we can’t service it,” says Dr Xiaofeng Wu, the lead of the “In-Space Servicing, Assembly, and Manufacturing” (ISAM) project at University of Sydney.

“With the advance of robotic technology, control technology, and artificial intelligence, it enables us to potentially service satellites in orbit,” Wu told Cosmos.

This precarious cosmic dance is no walk in the park. The repair robot would have to meet the broken satellite in space at the perfect speed to ensure there’s no chance of collision. Then a robotic hand will need to deftly repair the satellite issue, all without any human input – the lag time would be just too long and so AI will be required.

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Dr Xiaofeng Wu and Mr Julian Guinane with a robotic arm. Credit: Luisa Low, University of Sydney

“We have four packages. The first is to enable autonomous path planning or trajectory optimisation,” said Wu.

“We need to develop the senses to inspect the target in the space environment … that could be different sensors like infrared, LiDAR.”

This helps the repair robot make its way to the satellite and attach without causing damage.

“Another challenge is the control of the robotic arm, because in obit it’s a free-floating environment or zero gravity. So, when the robotic arm is in motion, it will affect the stability of the servicing satellite.”

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Recent research by the team has put forward papers suggesting 3D printing while in space to repair broken parts of the satellites and mechanisms for how to best control the robot.

Of course, Wu’s team isn’t the only one working on this. NASA in the US, the ESA in Europe, as well as a number of private companies are all racing to try and solve these problems, but although demonstrations are planned in the next few years, no one has yet solved the problem entirely.

Plus, with an increase in Australia’s space sector, having the ability for an Australian company to repair satellites without having to go overseas is particularly attractive.

Satellite CRC SmartSat is funding the ISAM project with a $1.05 million grant.

“Australia needs to start laying the groundwork now to compete in this vital and emerging $US14.3 billion market,” says Wu.

“This core capability set will enable Australian industry to undertake advanced, fit-for-purpose, autonomous robotic satellite missions to meet commercial, civil and defence needs.”

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