A “selfie stick” for a satellite? It sounds strange. And simple. But it’s one of those typically tricky – and necessary – challenges facing Australia’s emerging space industry.
The University of South Australia was one of three universities and 23 businesses of the iLAUNCH hub to share $180 million in funding this week to secure a future sovereign space industry.
They all face the same challenge: to build lightweight but resilient satellite components locally.
For UniSA, manufacturing specialists Amaero and SMR Australia, and the Defence Science Technology Group in Adelaide, the focus is on 3D printing.
“The selfie stick is a concept to give the public an appreciation of what we’re trying to do,” says Industry Associate Research Professor Colin Hall.
And that’s being able to fabricate complex optical components for satellite imaging systems.
So why do satellites need “selfie sticks”?
“We need to know what’s happening to them,” he says. “We want to see everything. Did it deploy right? Did an electrical short cause a malfunction? Or was it some sort of external influence – like a solar flare?”
It’s part of a project to develop a “black box” flight data recording system for satellites.
“It’s very challenging to get anything to operate properly in space, and that’s after getting it qualified and certified,” he says.
It must be of high quality. It must be reliable. It must be lightweight. It must be durable.
It also must burn up in re-entry and not punch any unexpected holes in the ground.
That makes something as traditional as an optic lens a challenge.
“You can take the traditional manufacturing route with a block of aluminium alloy or titanium, machine it into shape and polish it to the right tolerances,” says Dr Hall. “But we came from a different position not normally associated with high-end optics – 3D printed plastic”.
UniSA’s done something similar before. In 2011, it came up with the first plastic mirrors for the automotive industry.
“We had to pass all the certifications such as being resistant to harsh chemicals, abrasion, pressure and heat,” Dr Halls says. “It was a matter of having a lightweight mirror and finding new places to put it”.
A 3D printer builds a space-grade plastic formulation into the necessary interlocking shapes. Then a vacuum deposition technique applies a 50-nanometer thick layer of reflective metal. This is then given a protective clear ceramic coating.
“You have to get the chemistry right, the temperature right and the pressure right,” he says.
The end result is a high-quality optic finish on a set of perfectly fitting lenses. While the manufacturing process is complex, the end product is as simplified as possible.
“It’s more easy to create complex shapes,” says Dr Hall. “That means you can simplify the optics to the point where you may only need one camera lens capturing an image of the whole satellite”.
Another advantage of 3D printed optics is their weight and density. They’re about half that of comparable glass and one third that of titanium-based components.
Among them is establishing the thermal expansion properties of any 3D printed plastic framework. One side can be facing the extreme heat of the sun. The other is in the cold black shadow of space.
At stake is a place in the burgeoning low-Earth observation satellite industry.
“There’s much more demand now for high-end optical components,” Dr Hall says. His team is also working with the CSIRO to produce selective filters for the sensors on its upcoming Aquawatch water quality observation satellite.