Sail by Light

LightSail-A spreads its wings.

LightSail-A spreads its wings.

It’s a great time to be a space enthusiast. NASA is up to all kinds of cool stuff, the European Space Agency is starting to put their mark on space, and private organizations are springing up all over the place. In addition to commercial space companies like SpaceX, there are non-profit organizations devoted to exploring new frontiers, and seeking out new life.

Foremost among these is the Planetary Society. Originally founded by Carl Sagan, it is now presided over by Bill Nye. And their latest project is one of the coolest things yet–a real life honest-to-goodness solar sailer.

The idea of sailing on solar wind has been around for a long time. Jules Verne mentioned it in his famous moon-landing story A Trip to the Moon. And before that Johannes Kepler made a visionary comment that:

Provide ships or sails adapted to the heavenly breezes, and there will be some who will brave even that void.

–Letter to Galileo, 1620

Solar sailers have been capturing the imagination of science fiction writers ever since we discovered solar wind. The idea is that if you launch a space ship with a large enough sail it can capture enough of the ejected plasma material from the sun to propel it through space. Solar sailers travel at sub-light speeds, but will continue on indefinitely, making them an ideal type of ship for long interstellar voyages. Until a meteoroid tears the sail, that is.

Solar sailing space ships have been depicted many times in science fiction. In The Mote in God’s Eye by Larry Niven and Jerry Pournelle a solar sailer appears in a human settled part of space, alerting them to the presence of alien life forms. By the time it arrives it has been centuries in transit, and its occupant is dead. However, the characters are able to determine it’s trajectory, and make first contact.

A Bajoran light ship from Star Trek: DS9

A Bajoran light ship from Star Trek: DS9

Solar sailing is also given a spotlight in season three Star Trek: Deep Space 9 when Captain Sisko recreates an ancient Bajoran “light ship” and attempts to sail it to Cardassian space. The ship gets caught in an unknown stream of tachyon particles, accelerating them to warp speeds and proving Bajoran’s mastery of early space flight.

Last but not least, the idea of sailing on the power of light was taken to its logical steampunk conclusion in the film Treasure Planet. Fully rigged pirate ships sail the open skies on the power of light, rather than wind. Scientifically improbable, but visually amazing.

But what about real life? There are many problem with solar sailing including the slowness of the ship, the vulnerability of the sail, and the sheer size needed in order to collect enough solar emissions. But that hasn’t stopped the Planetary Society from trying.

On June 7, 2015 LightSail-A deployed its sails. LightSail-A is the prototype for LightSail-1, which is scheduled for launch in April 2016. If successful it will be visible from the ground, even in the daytime, and two more LightSails are planned.

The LightSail is a CubeSat, a tiny satellite designed for experiments in space. Its sails are 344 feet of Mylar, deployed in four triangles. While this little ship certainly isn’t going to carry any settlers to a new world, it was originally proposed for a rendezvous with Halley’s comet in 1975. While the project was dropped due to time constraints, it formed the basis of the researched being conducted by the Planetary Society.

LightSail--artist's depiction

LightSail–artist’s depiction

So what’s next for solar sailing? Keep watching for the launch of LightSail-1 next year, and support the project to see even more solar sailers from the Planetary Society! Their research is being watched closely by NASA, who plan to launch at least one solar powered CubeSat in 2018 to orbit the sun and detect near-earth asteroid. Solar sailers have been proposed for everything from exploring the Oort cloud, to interstellar voyages. If their viability can be proved then we may once again see the unfurling of (very, very large) sails as a symbol of adventure and exploration.

Katie Lynn Daniels is the author of Supervillain of the Day, and the mastermind behind Vaguely Circular. She blogs about science and things that are peripherally related to science. You can read all her posts here.



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