Stromlo’s role in reaching for the stars

Physicist Prof Christine Charles… “With this kind of device, you can test pretty much any equipment which will be used in space – and you really have to.” Photo by Gary Schafer

Physicist Prof Christine Charles… “With this kind of device, you can test pretty much any equipment which will be used in space – and you really have to.” Photo by Gary Schafer

IN a few months, Minister for Industry Ian Macfarlane will cut the ribbon on the ANU’s space simulator, a custom-built $3.8 million machine for stress-testing anything that needs to survive being hurled off the planet into the harsh conditions beyond our comfortable atmosphere.

The large, barrel-shaped device will be a valuable addition to Australia’s growing space industry, but to the physicists and astronomers who commissioned it, the shiny beast has already proven its worth.

“With this kind of device, you can test pretty much any equipment which will be used in space – and you really have to,” says physicist Prof Christine Charles, the head of the ANU’s Space Plasma, Power and Propulsion laboratory (SP3), explaining its main features are to replicate a vacuum, unfiltered solar radiation and a temperature range of about 80C to minus 170C.

This impressive piece of kit is the centrepiece of the futuristic-looking Advanced Instrumentation Technology Centre on Mount Stromlo, which also boasts a certified “clean room” plus an exceedingly quiet anechoic chamber, and is soon to have its own satellite shaker to simulate the powerful tremors of a rocket launch.

“It’s very unique really,” says Charles. “In other places they have similar facilities but not exactly like this. The design is really good; it allows for a lot of different configurations, so we hope that it will be of interest to a lot of other people. We already have quite a few collaborators worldwide, and it’s not even officially opened yet.

“We have much more control over our tests now and this is a really big advantage, because for the past 15 years we have been doing tests in other people’s chambers and this is really, really difficult… it’s very time consuming, it costs a lot of money and you have to have the right people at the right place at the same time, which is nearly impossible these days.”

Charles is testing the world-leading Australian Plasma Thruster, the best of the next generation of space engines that will need to reliably drive a spacecraft over long distances such as the trip to Mars.

“With a regular rocket, you would have to have so much fuel to get to Mars that you could barely carry it all,” she explains. “You might be able to do it, but how to come back again?”

Electric thrusters are all about slow and steady. In 2006 the tiny SMART-1 spacecraft took about a year to reach the moon, but it did so by firing its thruster for around 5000 hours, using only about 50 litres of Xenon as fuel.

“So if you’re patient, it’s better to use an electric thruster, and it’s always accelerating so the longer the mission is, the faster your spacecraft will travel,” says Charles. “For example, the time to get to Mars would actually be less than for a chemical rocket.”

Plasma is a state of matter like solid, liquid and gas; just as a liquid can be frozen solid by lack of heat, a gas can be ionised with electrical current, turning it into a hot, glowing plasma, which is what happens inside neon and fluorescent lights.

“You can make these ionised or charged particles do the things you want by using electric fields and magnetic fields, but at the end of the day, with a rocket, you just want to eject matter in the exhaust,” Charles explains.

“That creates the force in the opposite direction – the thrust – which is why they are called thrusters, so you can do that chemically, with a combustion reaction, or by emitting a plasma.”

Another advantage of plasma thrusters is they can use various common gases as fuel, she says, listing argon, xenon, nitrogen, oxygen and carbon dioxide, which is abundant on Mars.

The basic idea is decades-old and the Australian project goes back to the pioneering work of her colleague Prof Ron Boswell, who produced a revolutionary benchtop prototype in the early 1990s, naming it Wombat due to its barrel shape and stubby legs. It turned out the much larger space simulator looks basically similar, so it was named Wombat XL.

After coming from France to join Boswell’s team, Charles made her own breakthrough that led to her inventing the world’s first Helicon Double Layer Thruster, vastly improving the core technology of the Australian Plasma Thruster and putting it ahead of the rest.

“We’re getting pretty close now,” she says. “With this type of facility you can go from a laboratory idea, through all the development steps until you get ready for a space launch.”

As for the first return trip to Mars, Charles says it will be a worldwide collaboration, but believes her Helicon Double Layer technology will be a big part of the story.

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