You can just about get into orbit on a shoestring budget and now, once there, you can move your satellite with space fuel from the fumes of a few mothballs.
Canberra-based Boswell Technologies and the Australian National University’s Space Plasma Power and Propulsion Group successfully put their naphthalene-powered ‘Bogong 1 Thruster’ into orbit. It’s part of the payload of a Canberra-based Skykraft satellite launched by Space X on January 3.
It took six months of design, development and testing to build the innovative engine.
Now the ANU team behind its creation is watching it orbit overhead – and waiting for the green light to “fire it up”.
Skykraft is undertaking the slow but steady process of establishing contact with each of its four satellites. The Bogong is a subsystem of one of them.
“It’s in orbit, but we’re still suffering from butterflies as we wait to communicate with it,” says Technical Manager of the Bogong Thruster Project Dr Mahdi Davoodianidalik. “But once we do, to be honest, we’re really sure about ourselves. We’ve done a lot of testing, so we’re certain about that part.”
At normal temperatures, the hydrocarbon naphthalene is a solid – like mothballs. It’s also very safe which means it doesn’t need much effort to handle or contain when sending it into space.
When heated, it transitions directly from a solid into a gas. Exhausting that gas produces thrust.
Dr Dimitrios Tsifakis developed the concept as part of his PhD at the ANU Research School of Physics. Its low-tech simplicity proved immediately appealing to Australia’s rapidly expanding space industry.
“Everyone is trying to develop propulsion systems based on different concepts,” says Professor Christine Charles. “But this is the simplest concept.” It was developed in the laboratory at ANU, with industry partner Boswell Technologies.
Traditional chemical thrusters rely on bulky, volatile fuels and an oxidiser. These produce powerful thrust, but burn through fuel quickly. On the other hand, electric thrusters such as ion engines, are more fuel efficient and commercially available, but are more complex and consequently expensive. There is a need for a wider range of options for micro-and nano-satellite propulsion.
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Davoodianidalik says the Bogong thruster fits somewhere in between.
The naphthalene sits in a small container separated from the rest of the satellite to avoid any heat conduction. Staying in the dark is enough to keep it solid. But once heat is applied, the naphthalene begins to sublimate – and a valve releases that as thrust.
“It’s not necessarily the most efficient thruster, at least not yet,” Davoodianidalik says. “We hope to get it better. But it does give you a range of thrust in a neat, simple package”.
He was sufficiently impressed by the progress being made in the R&D that he purchased two. One is in orbit now and the second to be launched mid 2023.
“That’s usually the hard part,” Davoodianidalik told Cosmos Science. “I can remember the first few meetings where we all sat down trying to figure out everything we needed to do.”
The ANU team had a deadline. The SkyKraft satellites were almost ready to ride SpaceX into orbit. So in just six months of late nights, deep discussion and intensive testing they produces a reliable, working thruster.
“Normally, these projects take at least three years,” says Davoodianidalik.
The design and construction were kept as simple as possible. Only once a proven product was produced were any extra features considered.
“SkyKraft wanted another Bogong engine,” Davoodianidalik says. “So we added one more feature, tested it thoroughly, and delivered it by December last year. That almost doubled its efficiency. Now Bogong 1.1 is due to go up in a satellite in mid 2023”.
“I really appreciate seeing something I have worked on in use and someone is happy to have it,” Davoodianidalik says. “Now that we have delivered Bogong 1.1, we’re aiming for a Bogon 2 – a next-generation design”.
But first comes the flight test of Bogong 1.
“That will be the really exciting part, for us all to be sitting around a console and sending that command … ‘fire up’.”
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