NASA is looking at a new approach to solar sails. They intend to address the main disadvantage of present sails, which is their lack of flexibility in the direction of motion, by incorporating diffraction gratings into them. The sun exerts a force. Aside from toys that spin in a vacuum, this is generally overcome by air resistance and friction on Earth. It has an impact on the motions of asteroids and the dust that makes up meteor showers in space, making it more difficult to anticipate their courses. Engineers theorized a century ago that spaceships might travel to distant planets using massive sails instead of fuel or propulsion.
The concept has piqued public interest to the point where a small test sail was launched following crowdfunding, followed by a bigger one. Although the idea’s viability was shown when the Japanese Space Agency piloted the IKAROS probe to Venus in this manner, it has one fundamental flaw: control over the direction of motion is restricted. Sails like these don’t handle abrupt changes in angle relative to the Sun well, much alone tack like sailors sailing against the wind. Rigging that addresses this in part adds weight to missions that can’t afford it.
Some engineers, on the other hand, claim they have discovered a method around this. Their study is persuasive enough that NASA has spent $2 million in it as part of a Phase III award to investigate it further. “We’ll need creative, cutting-edge technology to fuel our missions as we push further out into the cosmos than ever before.” “NASA Administrator Bill Nelson made the announcement in a statement. “The NASA Innovative Advanced Concepts program assists in unlocking and bringing visionary concepts closer to reality, such as innovative solar sails.”
Instead, the new proposal involves embedding fine gratings in the sail, through which light will diffract, as waves do when passing through gaps of similar width to their wavelength. Phase me and II awards have already demonstrated the feasibility of making diffractive sails and bending light through them. When phase II funding was announced, Professor Grover Swartzlander of Rochester Institute of Technology said, “Unlike a reflective sail, a sun-facing diffractive sail experiences a component of force perpendicular to the sun line, thereby allowing navigation without sacrificing the amount of solar power on the sail.” Diffraction sails, according to Swartzlander, would also minimize overheating, which might be a concern with reflection sails.
Naturally, the concept works best where the sun shines brightest, therefore the first expedition to deploy diffractive solar sails will most likely be a voyage to the Sun’s unexplored poles. However, the same tactics might be useful for long-duration missions that don’t have enough fuel to make many changes in orientation over a lengthy period of time. “Diffractive solar sailing is a new spin on the lightsail concept that has been around for decades. While this technology has the potential to improve a wide range of mission architectures, it is most likely to have a significant influence on the heliophysics community’s demand for unique solar observation capabilities “Amber Dubill of Johns Hopkins University, the team’s leader, stated.
“We intend to let scientists to observe the Sun like never before, thanks to our team’s combined experience in optics, aircraft, classic solar sails, and metamaterials.” The concept is linked to, but distinct from, ideas to explore adjacent star systems using lasers to accelerate comparable sails to huge fractions of the speed of light. However, by employing lasers to control the orbits of boats with diffractive sails, the two theories might be combined.
