Solar sails are one of the more unique and efficient ways to travel through space. On the 9th of June, 2015 The Planetary Society‘sLightSail-A spacecraft successfully deployed its four triangular sails in one of the first successful deployments of a solar sail, and the first time a private venture has deployed such a craft, which is currently in low Earth orbit. California Polytechnic State University, San Luis Obispo recieved a photo confirming the unfurling. This paves the way for LightSail-1’s flight test scheduled to start next year.
LightSail-A with the Mylar solar sail fully deployed. Credit: The Planetary Society
The LightSail-1 started as a continuation of NASA’s NanoSail-D project. NanoSail-D was developed and set for orbital tests, but suffered a failed stage separation on the Falcon 1 launch vehicle and was lost in the Pacific Ocean. NASA handed off their information on the project to the international non-profit conglomerate devoted to space exploration: The Planetary Society.
Keen to prove the technology, The Planetary Society built a smaller testbed dubbed LightSail-A, which was launched on May 20th after being built by Stellar Exploration Inc. out of San Lois Obispo. It was placed in a very low orbit so that atmospheric drag will cause the spacecraft to de-orbit after testing. This helps keep low Earth orbit clean.
Unfortunately, two days after launch, the spacecraft suffered a malfunction which caused it to lose communications with the ground and fail to deploy the sail. The Planetary Society managed to regain communication with the craft and upload new software over the course of two days in preparation for the deployment of the sail. Communication continued to be troublesome as the spacecraft attempted to deploy its sails while rapidly losing altitude. Several days of spotty communication continued until Cal Poly finally received the image above confirming deployment. The Planetary Society declared the mission a success and held a press conferenceto answer questions about the mission, featuring Bill Nye the Science Guy and several members of the board of directors.
BRIEF HISTORY OF SOLAR SAILS
Solar sails have caught the imagination of scientist for years; the first imaging of a solar sail came from Johannes Kepler over four hundred years ago after observing a comet’s tail trailing away from the sun and hypothesizing that a ship with a sail could make use of this wind. Though many scientists have pontificated about using solar winds, it wasn’t until Friedrich Zander that the solar sail as we know it was conceptualised. Unlike conventional spacecraft that require fuel in order to move, solar sails take a page out of the terrestrial sailboat’s book and uses a large reflective sail to reflect and absorb photons to propel the spacecraft. As a result, the solar sail has a near unlimited amount of range so long as you’re willing to wait for it to pick up speed.
Artist’s depiction of the IKAROS spacecraft. Source: Andrzej Mirecki
The first successful demonstration of the solar sail technology was developed by the Japan Aerospace Exploration Agency and dubbed the “IKAROS.” In May of 2010, the Interplanetary Kite-craft Accelerated by Radiation Of the Sun started on a course for Venus, and was able to reach its destination by December the same year. This proof of concept paved the way for future solar sails and is still functional today, though it remains in hibernation mode.
THE FUTURE OF SOLAR SAILS
With the successful deployment of the sail, the Planetary Society’s next goal is the 2016 launch of LightSail-1. The group hopes the LightSail-1 will reach high relative speeds after being placed in to a much higher orbit compared to the LightSail-A. Its mission is to determine the viability for solar sails as a means of propulsion within stellar space. While it is expected to be successful given the success of the IKAROS spacecraft, two successors named LightSail-2 and LightSail-3 are planned on being put into production with more complex goals upon the completion of the LightSail-1’s mission.
Other companies and space agencies are researching the solar sail technology, which has the potential to revolutionize space travel. The lack of fuel means smaller, lighter spacecraft, requiring less fuel to launch and thus less expensive ventures. Larger solar sails could provide better acceleration, allowing shorter times to distant objects like the moons of our gas giants and beyond. Currently under development, the Near-Earth Asteroid Scout (NEA Scout) would use a solar sail to approach a nearby asteroid as a precursor to the Asteroid Redirect Mission NASA hopes to do in the near future. With the proper development, solar sails could be the affordable stellar propulsion system of the future.
