Faster-than-light space travel looks very attractive on paper. Astronauts probably dream about FTL when they’re floating snugly in their orbiters and space stations. We can get very pushy in our rush to the stars, but we’ll need to be patient. In the interim, our brightest minds are coming up with alternative spacecraft that can carry our next generation of explorers.
Liquid fuel may one day become an archaic substance for an orbiting vessel. In an ideal setting, a spacecraft must utilize a power source that is renewable and readily available. Power sources should keep a ship at cruising velocity between Earth and her sister planets. Energy should also be clean and safe for the manufacturers, handlers and crew. A few years ago, I began munching on the concept of a solar ship. Why not grab the closest and hottest power outlet in our solar system to cruise around the block?
The concept has been around since the early 1900s. Again, it looks nifty on paper. The idea centers around an enormous surface that can collect radiation pressure and solar winds. If the stuff builds up in your sail, you earn enough inertia to move your attached spacecraft. It may take time to build escape velocity from Earth orbit, but once you’re free to navigate, you have a free vector without any concern for fuel consumption. Ancient mariners and sail masters would catch on to this delightful theory.
There are limitations to the current theories of solar sails. You need time to collect solar energy in order to move. A giant surface like the one pictured above is not ideal for minute or precise course correction. (The vessel might require secondary propulsion, like attitude thrusters, for that purpose) And in the early 21st century, the endeavor of constructing, packaging and deploying such a broad control surface is difficult. You might be able to propel a solar ship using a projected beam from Earth or the Moon, or even from the vessel itself. Yet again, we are restrained by the means in our decade. How can we build it? When will it happen? Practical questions follow the inventors around every corner.
Like the scientist or engineer, I dream about these ships. My handle on space engineering is very limited, but I continue to dream nonetheless. There are practical applications for this technology. I imagine a vessel with an enormous sail maintained by peppy little ROVs on its way to a distant star. Satellites can use sails to avoid declination and stay out of the atmosphere. I wait for the future, even if I never live to see a solar sail unfurl. We should be proud of the ones who made it, the ones who sailed it, and the ones who keep going.