The project to develop the various solar sails has progressed to NASA’s advanced program’s third and final phase. The project team now has two years to continue developing these unique ways of moving space.
In addition to the two-year extension, NASA announced today that the diffractive light sails project, led by Amber Dubill of the Johns Hopkins University Applied Physics Laboratory, was awarded an additional $ 2 million. Phase 3 funding is provided through the Innovative Advanced Concepts (NIAC) space program. With more time and money, Dubill and his colleagues are about to work on a demonstration campaign.
“As we move forward in the universe more than ever before, we will need new, state-of-the-art technology to advance our mission,” NASA director Bill Nelson said. “The NASA Innovative Advanced Concepts program helps unlock ideas – like sails with a solar novel – and brings them closer to reality.”
The diffractive solar seils project graduated from NIAC phase 2 in 2019. Rochester Institute of Technology Engineer Grover Swartzlander has led the first two phases of the NIAC for this project and will now continue as a joint investigator.
“I am very happy to be joining a group of thoughtful and intelligent people who make up the NIAC. I’ve actually been involved in various NIACs since 2017 in various fields, but being able to lead is a dream come true,” Dubill wrote to me in an email. “For years I have been guided by [my fellow researchers] and it means a lot that they can trust me to lead in this and continue to develop this research in an institution that promotes this kind of innovation.”
Solar sails use sunlight to propel vehicles into the atmosphere, just as the wind blows boats into the water. Instead of using light sails like the one developed by the Planetary Society, the proposed system will use different sails. A desirable feature of diffraction is that it diffuses light through a small hole. Here is how Swartzlander described the concept in 2019:
We are entering a new era of space travel using the pressure of the Sun’s rays on a large, narrow canvas. A common idea of the last 100 years was to use a light sail like a metal cover in a small polymer and open it up in space, but you can get the power based on the law of diversity. Compared to a light sail, we think that a diffractive sail might be more efficient and can withstand the heat of the Sun better. These sails are transparent, so they will not absorb most of the heat from the Sun, and we will not have trouble controlling the heat as you do with metal.
The shortcomings of the standard light design include large and trim sails. They are also limited in the direction of sunlight, which works to force or navigate, as you will not have both. Separated light curtains, by comparison, use a small grate on the sail to separate the light from all sides. According to NASA, this will allow the spacecraft to “use the sunlight more efficiently without sacrificing its movement.” Dubill’s proposed design may result in smaller and smaller sails. And as a happy side effect, the sails will have a rainbow pattern, similar to what CDs look like when caught in the light.