The Bogong thruster has flown. It has proven the material behind mothballs can provide a kick in orbit. But not without a bit of flap. And a lot of waiting.
Canberra-based Boswell Technologies and the Australian National University’s Space Plasma Power and Propulsion Group are basking in the glow of success – after embarking on a fast-tracked design, development and testing program on somewhat more than a wing and a prayer.
“We aren’t people who work on paper and blab,” says Boswell Technologies CEO Professor Rod Boswell. “We actually went to the lab and machine shops and made certain you could see it working in a vacuum environment, on a thrust balance, before putting it out there.”
The Bogong thruster is built to exploit the chemical properties of naphthalene. It’s inherently safe. It shifts rapidly from a solid to a gas. And it has a low vapour pressure.
After a June launch, Bogong 1.1, the second prototype, was successfully test-fired aboard an Australian Skykraft satellite mid November. The first example was sent towards space in January. But a communications link with that satellite was never established.
Technical Manager of the Bogong thruster Project, Dr Mahdi Davoodianidalik, says that’s just the first of many stomach-butterflies-inducing steps when putting a prototype through its paces.
“Once it’s launched, it’s a relief. We’ve delivered what we said we would when we were supposed to. But, at the same time, it’s no longer in our hands. We have to sit back and pray everything works.”
Read more: The Bogong thruster
“The first thing we needed to do was see if the Bogong was alive or not,” says Davoodianidalik. And that happened less than two months after launch.
“Skycraft sent a query to the Bogong – and it came back “hello”.”
Two months may sound like a long time. But first, ground stations have to find the individual satellite, establish a “handshake,” and ensure its central motherboard is fully functional.
All this – and everything else – can only be done in a 10-minute window for each 90-minute orbit.
“To be honest, I’d really have loved to go there and send the command and wait for the response myself,” says Davoodianidalik. “I definitely wanted that job. But it wasn’t something we could do. It wasn’t our satellite. And there was a whole lot more riding in on it than our thruster.”
Then, every subsystem of the Bogong had to be activated to test its condition.
“The first came back fine. And we were really happy with that,” says Davoodianidalik.
“But the second threw up an error. It was the worst thing that could have happened! This was the machinery most at risk from the vibration and strain of launch. And I couldn’t go up there and look at it!”
The diagnostic process was somewhat more advanced than the usual “turn it off and on again”. Instead, the combination of conditions, commands and feedback was analysed in the ANU’s lab to tailor a different version of the same command.
“We don’t know what went wrong the first time,” Davoodianidalik explains. “It could have been a glitch in the transmitted code. It could have been anything. But we had tested the Bogong so many times here in the lab in the vacuum chamber that we could replicate the error and explore how to solve it”.
The Bogong team was ready to go.
But they had to wait.
“It was quiet for quite a while. Longer than I expected, to be honest,” says Davoodianidalik. “But this wasn’t just a test for Skykraft. It was something that would affect their operations.”
Then, early one morning, an email landed.
“They said they’d fired it up, that it works, and that it had moved the satellite in the way everyone expected,” he says. “That was it. That’s what it was supposed to do. That’s what it was designed for. And that’s exactly what it’s now done, in orbit!”.
The test results and experience are now being fed towards a redesigned Bogong Two.
“This time, we can aim at the market,” says Davoodianidalik. “We can design a product any company can connect to their satellites.”
Proof of concept – known as “heritage” in the space industry – is a significant hurdle now behind the thruster project.
“You have to be dead bloody honest in this game, in my view,” says Boswell. “You have to have habeas corpus, to show that the thing works like you say it does!
“Our Bogong works on sublimating naphthalene to produce a vapour. But it’s certainly not vapourware, which we see a lot of when looking at space industry social media”.
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