Liquid lenses for better satellite monitoring

HIAF's space irradiation beamline has played a vital role in an exciting first for the Australian space industry: the first time that Australian space radiation testing has been done on an Australian space payload. The occasion? Testing innovative liquid lenses that enable a satellite to take a selfie.

Cameras on satellites, including CubeSats, are nothing new. They're typically included to take photos of the Earth and monitor climate patterns. However, a Defence Science and Technology Group (DSTG) team is about to send a satellite into orbit with a camera that also looks back at the satellite itself.

DSTG's newest satellite, called the Buccaneer Main Mission, includes a special deployable arm that can extend out and retract, and a rotatable mirror with two surfaces, one aimed towards Earth and the other at the satellite.

Read more: Space Systems Engineer, Franke, has designed a first-of-its-kind imaging system for the Buccaneer Main Mission project.

Making sure the satellite's key antennae deploy properly and stay stable is important for the mission to succeed, so DSTG made a unique piece of imaging equipment to look at the antennae and the satellite itself. Without it, there's no way to examine the satellite to check for failed antennae deployments, and damage from radiation, micro-meteorites, or other space hazards.

However, the camera from that system also needs to focus on things much further away - like Earth. That wide range of focus brings some challenges in space.

"In space, if you have two metal components touching each other, they weld together and don't move, so focusing a lens by mechanically moving something is very difficult to do," explains Chris Peck, who leads resilient spacecraft development at DSTG.

The solution was to use a liquid lens: a cell with two liquids that change shape when a voltage is applied, which changes the lens's focus without any moving parts. The lens can adjust focus quickly and precisely, allowing it to focus on faraway objects like Earth or nearby objects like the satellite itself.

Liquid lenses weren't initially designed for space, but they have a lot of benefits. They provide a wide range of focus with precise adjustment in a small space and are relatively cheap and robust, with no mechanical parts to break.

Since it's never been used in space before, DSTG had to thoroughly test their liquid lens technology to make sure it could handle the harsh conditions.

To see how the lens reacts to damage from radiation, different lens samples were exposed to increasing intensities of high-energy proton beams at HIAF, the only facility in Australia that can produce such beams.

"HIAF is the only place we could go to do this level of testing at the energies we needed," Chris says.

None of the lenses showed any degradation in their optical performance after the tests, indicating they could handle the kinds of radiation they would be exposed to during the mission - good news for DSTG and the future of the Australian space industry alike.

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