NASA-Funded Solar Sail Uses Metamaterials to Generate More Power

The Advanced Diffractive MetaFilm Sailcraft could squeeze more energy out of light than traditional reflective sails.

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Jul 18 2018, 12:00pm

Image: NASA

If you wanted to spotlight two of the most dazzling futuristic technologies in development right now, solar sails and metamaterials would be excellent picks. Solar sails, light-based spacecraft propulsion devices, have been suggested as the most promising method of interstellar travel, while metamaterials, synthetic structures with unnatural properties, have already revolutionized numerous STEM fields (think earthquake-resistant buildings, ultra-rapid data processing, and cloaking devices).

That’s why it’s fascinating to see these two emerging technologies merge in a new spacecraft concept, the Advanced Diffractive MetaFilm Sailcraft. The brainchild of Grover Swartzlander, an imaging scientist at the Rochester Institute of Technology, the solar sailcraft is designed to harness photon power with much more precision and efficiency than current solar sailcraft platforms.

The idea was recently awarded Phase I funding of $125,000 from NASA’s Innovative Advanced Concepts (NIAC) Program, which supports visionary ideas with the potential to shape the future of space exploration. Unlike some NIAC proposals, which anticipate technologies that could take decades to develop, the basics of the metafilm sailcraft could be tested out in space today.

“There are already various commercially available metamaterial diffractive structures that could be used for a small demonstration mission, say, from the International Space Station,” Swartzlander told me in an email.

NIAC has funded many trippy solar sail proposals in the past, but Swartzlander’s is the first to integrate metamaterials into the design, as opposed to relying on reflective surfaces coated with aluminum or other metals.

Traditional reflective sails generate momentum as photons bounce off their large surface areas (photons could originate from a star such as the Sun, or from laser pulses).

In contrast, Swartzlander’s metafilm model would use the bizarre light-bending properties of metamaterials to trap solar energy within diffraction grating structures, allowing much more energy to be harvested from the same amount of light. This could increase the fuel economy (so to speak) of solar sails, and provide a controlled-steering mechanism due to the metafilm’s superior manipulation of photons.

While the fundamental mechanics of the metafilm sail could be tested out in space at any time, Swartzlander outlined some obstacles. The sails would have to be extremely thin and lightweight, while also remaining tough enough to withstand launch conditions and the harsh space environment. They would also eventually need to be manufactured at sizes larger than ten square meters.

Read More: The LightSail Satellite Successfully Deployed Its Solar Sail

To approach these challenges, Swartzlander has organized a two-day “incubator” meeting this October in Washington, DC with the aim of boosting “the technical readiness level of diffractive sails.”

That meeting is likely to be followed by more years of exhaustive research about the potential of metafilm sails. But if they are successfully deployed, they could be instrumental in adjusting orbits of small satellites around Earth, enabling them to easily deorbit to prevent space clutter, and may even be used guide spacecraft within and beyond our solar system.

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