Solar Sails

Solar Sails: A Novel Approach to Interplanetary Travel
Giovanni Vulpetti, Les Johnson, and Gregory L. Matloff
Praxis Publishing, 2008, 256 pages
ISBN: 978-0387344041

For thousands of years, people explored Earth aboard ships propelled only by sail. Today, you can travel to almost anywhere in the world within 24 hours.

Though flight and fossil-fueled shipping have now superseded sailing, there might be another age of sail in store. Eventually, people might be able to travel through the solar system powered only by sunlight.

Thus far, humans have only encountered space through chemical rocketry, a risky method. In Solar Sails: A Novel Approach to Interplanetary Travel, Giovanni Vulpetti, Les Johnson, and Gregory L. Matloff point out flaws in chemical rocketry and paint a picture of space exploration by solar sails.

Though the sun spews charged particles forming solar wind, this wind is too weak and variable to power solar sails. Instead, light from the sun bounces off a highly reflective, very large and thin solar sail carrying a payload, putting force on the sail. While the force of light acting on a large surface area is the basic concept behind solar sailing, designs and methods for unfurling sails (sails that are able to unfold) vary substantially and aim to improve with time.

Engineers and scientists in several countries have built solar sails and their underlying support frames, testing the unfurling in atmospheric and vacuum environments. Cosmos 1, built by the Planetary Society, would have been the first solar sailcraft to fly in space, yet it never made it because of a faulty Russian launch vehicle that doomed the craft in 2005. Research for others is ongoing.

Solar Sails presents the advantages, outlines the current status, and emphasizes the future possibilities of solar sailing. In one section, the authors speak of giant lasers on orbiting asteroids that may be able to drive sailcrafts. Though the authors admit that the further they go into the future, the more fanciful their predictions, they write with optimism about humakind’s future in space.

As leading scientists in space exploration, the are certainly respectable authorities on the matter. Vulpetti is an Italian physicist who has served as chair of the Interstellar Space Exploration Committee of the International Academy of Astronautics; Johnson is the Deputy Manager for the Advanced Concepts Office at the NASA George C. Marshall Space Flight Center in Huntsville, Alabama; and Matloff is a professor of physics and coordinator of the astronomy program at New York City College of Technology (NYCCT).

Although no background in physics is necessary to read Solar Sails, the book does cater to more technical audiences as well with its final quantitative section.

Solar Sails can be dry at times, most likely a result of the instructive nature of the book and the large amount of information densely packed within. At times, the authors use explanation points at the end of sentences to bolster an excitement that may be lacking in the words themselves. Nevertheless, Solar Sails manages to present a complex topic in understandable terms and makes a convincing argument for the next generation of space exploration.