As he extols the virtues of the technology facilitating a satellite weighing less than 100kg, Tony Boschi shows the depth of his experience with the repeated use of two words: rapid prototyping.
Boschi has been working with 3D printing technology for so long, that he not only refers to the processes using that phrase, but he also has the war stories. When he first used the technology, for example, he and his colleagues took to squirting hairspray on stereolithography (SLA) parts to prevent the sticky texture they were left with when coming out of the printer, and in turn allowing any paint applied to the components to dry faster.
“It was one of the greatest things in the world,” he recalls thinking. But such glee is relative. These days, as Lead Design Checker at Sidus Space, he has printed sample holder parts in Markforged’s Onyx carbon fiber-filled nylon material that formed part of a flight test platform installed on the outside of the International Space Station (ISS) for a year. That the parts survived on the ISS with next to no degradation emboldened Sidus Space to push forward with the idea of producing the structure of its LizzieSat satellites with 3D printing.
Sidus Space was founded by Carol Craig, a former US Navy officer who became the first woman eligible to fly combat aircraft in the US Navy, to carry customer sensors and collect data for a multitude of different customers at the same time.
The partially printed LizzieSat constellation will launch for the first time later this year on the SpaceX Transporter-9, if it weighs less 100kg.
This has represented a significant challenge for Boschi and the Sidus team, especially since integral componentry like batteries and computers take up a significant portion of the satellite’s overall weight. But it is one they backed themselves to overcome with the combination of their engineering prowess and 3D printing technology.
In the design of the LizzieSat, they have applied Markforged’s composite 3D printing technology to the entire structure of the 31 x 31 x 18 inch satellite, harnessing the company’s Onyx FR and Onyx FR-A materials on eight vertical and eight horizontal components that hold in place a honeycomb structure. With this use of carbon-fibre filled nylon, Sidus says it is able to leverage similar strength qualities to aluminium, while reducing the weight and iterating on designs much more quickly.
During design iteration, Boschi incorporated fastening functionality into the structural components so that parts fit into a slot and lock into place. This has not only helped to shave off weight by removing screws and bolts but has also made the satellite sturdier.
“When we started doing the preliminary analysis, you could see that when the parts were bolted together, they were all separate,” Boschi says. “But when we made the locking feature, then the entire ring became one piece, so that we’re only pulling on one structure, as opposed to 16 pieces –because there are eight columns and eight pieces in between to hold them together. Now we put everything together, they all get bolted to the honeycomb or the aluminium pan on the other side, it’s more of a stronger, stout structure.”
At the time of writing, Sidus is in ‘full print’ mode ahead of the prospective SpaceX launch later this year. The design has been locked in, the honeycomb and base plate are due for arrival in April, and then the satellite will go through an extensive testing process to prove out its durability. The LizzieSat satellite has been built for a five-year life, while Sidus has had to keep in mind that as it is launched into outer space, it will have to take 5G loads, withstand solar radiation, and deal with vast temperature swings of around 200°C as it goes from the exposure of direct sunlight to the shade of the Earth’s shadow.
For Boschi, he’s never been more sure that 3D printed parts can manage it. “When I first did parts years ago with SLA machines, we would break them taking them out of the machine. If you didn’t put it down right, it would break. And it’s advanced from that point forward. Now we’re in nylon. Better materials, it’s changing everything. From that point when I was first [using 3D printing], it’s night and day.”
