About Solar Sails

The Aristarchus in my novel The Solar Sea is a solar sail spacecraft. Solar sails are a real technology currently being investigated by NASA and other agencies as a way to propel spacecraft in the future. This page presents a few facts about solar sails, some links to solar sail projects, and how the Aristarchus fits in with real projects under development.

  • Solar sails are actually propelled by light. When light bounces off of a reflective surface, some of its momentum is transferred and it can cause the object to move.

    • The Aristarchus' sails are coated in aluminum to make them reflective.

  • The reason light pressure doesn't move things on Earth is because it provides a very gentle force. On Earth, gravity and air pressure are much stronger than light pressure. But in space, where gravity is weak and there is no air, light pressure can move objects.

  • Sunlight only provides two pounds of force for every square kilometer. So solar sails must be very large compared to the object they are propelling.

    • Because the Aristarchus is a manned spacecraft, the sails must be very large. They're over ten miles across.

  • Present day solar sails are being built out of very thin material because light pressure is so weak. The materials being investigated are between 40 and 100 times thinner than a piece of writing paper.

    • The Aristarchus' sails are made out of a type of plastic called quinitite. Quinitite hasn't been invented yet, but I imagine it to be very strong and lightweight. Perhaps it's a matrix of polymer nanotubes. The strength helps because of the sails' size and it helps deal with the real modern day problem of rips in the sail fabric.

  • NASA is in the process of developing solar sails. You can learn more at NASA's NanoSailD Page. There's even a slideshow showing the successful flight of NanoSailD.

  • The Planetary Society is a non-profit group that is also building a solar sail. Learn more at the Planetary Society's Solar Sail Page

    • The Aristarchus employs a similar design to the Planetary Society's original Cosmos 1 craft. Both use sails that spin on masts attached to a central hub.
  • For more about solar sails, read the article "Sailing the Winds of Space" by David Lee Summers serialized in three parts at his blog: