A Giant Ribbon Can Pull Payloads Along

Innovation is a history of someone trying to build a better mouse trap – or at least that’s how it’s described in business school. But what happens if someone tries to build a better version of something that isn’t even commonly used yet? Maybe we will soon find out, as NASA recently supported an effort to build a better type of solar sail as part of its Institute for Advanced Concepts (NIAC) program.

The project, called “The Ribbon” on its announcement page, is a novel take on a typical solar sail and is being developed by a company called TestGuild Engineering out of Boulder, which seems to be run by a sole proprietor known as Gyula Greschik, who also appears to be a researcher at UC Boulder. The Ribbon consists of a “film strip with a diffractive grating” that uses the same principle as a traditional solar sail to move – light pressure. 

The diffractive grating is the key here – when the Ribbon is oriented towards the light from the Sun, the light effectively “pushes” it, just like a solar sail. But, in this case, the diffractive grating causes the force to be directed toward the “leading end” of the Ribbon. Importantly, it does this with no structure components at all – just the Ribbon itself.

If a payload is attached to the other end, eventually, the force being applied to the front will drag the back along with it. It might not happen immediately, but like an actual ribbon, eventually, the force will be transferred down to the payload. That would allow it to effectively tow the payload, much like a traditional solar sail.

This does have some unique advantages, including its ease of storability and potentially infinite scaling—longer ribbons would simply mean more force, much like a larger solar sail would also mean more force. In theory, at least, there is no limit to the scaling of how large you could make the Ribbon, though practically, eventually, you would hit the physical limits of the material you chose to make it out of.

TestGuild has some experience developing projects for NASA already. Back in 2017, it was given a Small Business Innovation Research grant to work on a type of deployable communications array that uses similar structural engineering techniques to the Ribbon. It’s unclear whether that project is still ongoing, but given the new interest from NASA on a completely separate use case with the same PI, it likely isn’t.

 Comparing the Ribbon’s use cases to those of more traditional solar sails will take a long time. NIAC Phase I typically takes about a year. In the press release announcing the project, Dr Greschik notes that most of this round will be focused on simulation and feasibility studies. Special emphasis is placed on how the Ribbon responds to small perturbations and what control system would be necessary to stabilize it. So, it may be some time before we see a giant Ribbon pulling a payload through space. However, new solar sail concepts always pop up, and this one could provide some inspiration for the next generation of designs, or it could see itself manifested one day.

Learn More:
Greschik & NASA – The Ribbon
UT – NASA’s Putting its Solar Sail Through its Paces
UT – Project Helianthus – a Solar Sail Driven Geomagnetic Storm Tracker
UT – Solar Sails Could Reach Mars in Just 26 Days

Lead Image:
Artist’s concept of the Ribbon.
Credit – NASA / Gyula Greschik

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