Rocket launches are some of the most violent travel methods man has ever created. They generate millions of pounds of thrust and convert that into intense g-forces. Humans must undergo serious training to withstand those experiences, but machines have to do so as well, but by design rather than training. If a delicate mirror or solder joint cracks before a multi-billion dollar satellite even begins its mission, the years of effort that went into its design and assembly could be lost. Now, researchers in Switzerland have come up with an ingenious way to make sure that is much less likely to happen.
During a rocket launch, a satellite doesn’t just sit loosely inside the rocket’s nose cone (also called its fairing). It bolts directly onto an interface known as a payload adapter. Usually, these are rigid mechanical mounts specifically designed to make sure the spacecraft doesn’t move during flight. But because they are so stiff, they are also excellent at transmitting vibrations – especially longitudinal vibrations that shake the satellite straight up and down along with the rocket.
That is exactly the kind of stress that could cause those unfortunate failures, so engineers have long sought ways to lessen the impact of those vibrations. However, their solutions were less than ideal – they would use giant rubber cushions (which have their own history of space-based failures) or motorized dampeners that added further weight to the rocket’s payload.
Fraser talks about the kinds of payloads Starship will be capable of launching.
Swiss researchers from the Swiss Federal Laboratories for Materials Science and Technology (Empa) and aerospace supplier Beyond Gravity turned to a completely different technology for their novel payload adapter – phononic crystals. These metamaterials are intentionally designed to control, bend, or completely block mechanical waves – similar to how photonic crystals manipulate light.
The researchers built a prototype that redirects sharp vertical shocks into rotational motion, transferring that kinetic energy from the shaking rocket body directly into a set of movable aluminum rings. After transferring that much energy, the shock loses its power, lowering the stress on the internal systems of the satellites.
Since satellites are intentionally designed to survive the extreme environments of a rocket launch, any technology that lowers their structural reinforcement requirements is a welcome development. That, in turn, frees up payload capacity, either cutting launch cost or allowing more useful payload on the satellite itself. But it also allows scientists to fly even more fragile instruments, such as thinner optics or sensitive quantum computer sensors that would otherwise be destroyed by the vibrations of launch.
Video showing the vibration test of a payload adapter. Credit – Innospace YouTube Channel
There’s still a lot of work to do before these adapters find their way into mainstream use, though. Beyond Gravity has filed for a patent on the system, and it currently passed its computer simulation and lab bench stress tests. But that still only puts it at a TRL 4-5 on NASA’s Technology Readiness Level scale. So while it might be a while before we get to a point where we see regular adoption of phononic crystal payload adapters, the advantages seem clear cut compared to traditional mechanical systems. Assuming it doesn’t hit any further development hurdles, it’s only a matter of time before satellites finally have a much smoother, less weighed down ride to the stars.
Learn More:
SWI – New Swiss-developed adapter protects satellites from vibrations
UT – Rosetta Attached to Its Launch Hardware
Beyond Gravity – Payload Adapters
UT – Questions Remain on Chinese Rocket That Created an Unusual Double Crater on the Moon