On Monday, The Planetary Society’s experimental solar sail, LightSail 2 is scheduled to launch aboard a SpaceX Falcon Heavy. I’m a member of the society and one of this mission’s Kickstarter backers, so I’m really excited to see this mission getting underway.
Currently, LightSail 2 is tucked into a package about the size of a loaf of bread called a CubeSat and this CubeSat sits inside a suitcase sized satellite called Prox-1. Prox-1 will be deployed from the SpaceX rocket at an altitude of 720 kilometers, about an hour and twenty minutes after launch. About a week after launch, Prox-1 will open a hatch and the CubeSat will be ejected. At this point, onboard computers will boot up and ground control will start conducting tests. Presuming all goes well, about five days later, solar panels will be deployed and a day after that, the 32-square meter solar sail will deploy.
In solar sail theory, gravity is like the water currents that carry an earth sailboat. Photons from the sun are like the wind. The goal of LightSail 2 will be to show that the sail can orbit the Earth in such away that light pressure can carry it into a higher orbit. To do this, it needs to have the reflective sail facing the sun when being pushed away. Then it needs to turn its reflective surface away when gravity carries it toward the sun. This means that sunlight will give it a push every time the craft goes around the Earth.
As it turns out, the Japanese Space Agency, JAXA has already demonstrated that sunlight can cause a light sail to accelerate. In 2010, they launched a probe toward Venus. Piggybacked on that mission was a solar sail called Ikaros. With no other source of propulsion than sunlight, Japanese scientists saw Ikaros accelerate. The photo above this paragraph shows Ikaros in flight.
I’ve long been fascinated by the concept of solar sails ever since I first read about them in an early edition of The Planetary Society’s newsletter, The Planetary Report. In high school, I came up with the idea for a novel called The Solar Sea. I wrote a few chapters and then set it aside in favor of other projects. I finally returned to the idea almost twenty years later, in 2007. I defined the characters, determined the mystery they were solving, and wrote the book. It tells the story of humanity’s first voyage through the solar system aboard a solar sail spacecraft. In the novel, the astronauts visit Mars, Jupiter, and Saturn. At each stop, they learn more clues to the nature of life in the galaxy. The story expresses my love of astronomy, space exploration, and the solar system. If you’re as fascinated as I am about traveling on a space ship powered only by sunlight, I invite you to take a journey through The Solar Sea.