The concept of solar sails is not particularly new — just check out the Planetary Society's LightSail 2, French startup Gama or NASA's Advanced Composite Solar Sail System. But one group of researchers is pushing the technology to new heights.
The Diffractive Solar Sailing project as been awarded Phase III status in the NASA Innovative Advanced Concepts (NIAC) Program, which comes with a $2 million budget to bring the team's concept into reality.
Solar sails are a means of spacecraft propulsion that work similarly to sails on boats, but instead of being powered by wind, they're powered by light. Diffractive solar sails, such as the one being developed through NIAC, are a more efficient evolution of traditional solar sails that could one day aid space missions.
"Diffractive sails are based off the optical mechanism of diffraction, whereas traditional solar sails we have seen are based off the law of reflection," project lead Amber Dubill of the Johns Hopkins University Applied Physics Laboratory tells TechCrunch.
As before, photons hitting the sail impart their momentum to the spacecraft, but Dubill's team is working on a new twist on this proven tech:
The advantage of using diffraction to do this instead of reflection is the ability to tailor the angle at which the incoming light is redirected so that the resulting force is more efficient for orbital maneuvers without having to tack a large flimsy structure.
The Diffractive Solar Sailing project has already completed Phase I and Phase II of the NIAC program, which is NASA's high-risk, high-reward incubator that explores the possibilities of unusual technology in space. Those first phases are dedicated to developing concepts and proving their potential. Phase III, however, transitions the concepts into reality. (An aside: Since NIAC's inception in 2012, just five projects have been awarded Phase III status, as most projects don't prove enough potential in Phases I and II for NASA to pursue further.)
Dubill and her team will use the $2 million in funding to design and manufacture sail materials, which they plan to test at various facilities across the country over the next two years.
"In parallel, we plan to evolve the vision of a solar polar orbiter sailcraft mission by establishing optimal trajectories and attitude control of the sail to achieve the solar observations of a payload suite dictated by our heliophysicists," says Dubill. "Through expanding the diffractive sail design and developing the overall sailcraft concept, the goal is to lay the groundwork for a future demonstration mission using diffractive lightsail technology."
That solar polar orbiter mission is of particular interest to NASA, as our star's poles have not yet been explored. "Obtaining a full picture of the solar corona and surface magnetic fields are critical to space weather forecasting and awareness, and a constellation of instrumented sails circumnavigating the sun would not only improve our understanding of our nearest star, but would increase the warning time for solar events that may damage satellites and ground systems," Mike LaPointe, acting program executive for NIAC, tells TechCrunch.
The same technology could be used on similar missions throughout the solar system, suggests LaPointe. With such potential, it's little wonder that NASA has funded the Diffractive Solar Sailing project — now it just needs to get off the ground.