SAIL INTO SPACE

A Sun-Powered Sail into Space. Imagined by Astronomers from Johannes Kepler to Carl Sagan, a solar sailing spacecraft is poised for launch.

Do you know the current phase of the moon?  Most of us don't have any idea; nowadays we hardly need to know.

But before there were streetlamps and electric lights everywhere, people watched the night sky diligently. So when a very bright comet appeared in 1607, people were frightened and fascinated.

German astronomer Johannes Kepler thought deeply about what he saw that year.

He reasoned that the spectacular tail of what we now call Halley's comet 'named after the English scientist Edmond Halley, who computed its orbit] was probably caused by the sun's warmth somehow evaporating or liberating material from the comet's surface.

Kepler imagined exploring those stars scapes : ''Given ships or sails adapted to the breezes of heaven, there will be those who will not shrink from even that vast expanse,'' he wrote.

Ships after all were common enough in the 16th and 17th centuries, and they were driven by the winds, which are themselves created in part by the sun's warmth.

Kepler lived during a moment in history when, thanks to Nicolaus Copernicus, we came to understand that we're aboard a planet orbiting a star. Perhaps it was natural, then, for Kepler to envision humankind sailing the starry heaves.

As I sat in Carl Sagan's astronomy class at Cornell University in 1977, sailing through space certainly seemed natural to me.

Sagan vividly described his vision of a craft that could operate within the constraints of gravity and the mechanics of orbit and the mechanics of orbits, yet glide among the stars. It would sail the cosmic ocean, driven by the force of starlight in the vastness of space.

The dream that our professor outlined is now being realized by the Planetary Society, the world's largest nongovernmental space organizations, which Sagan co-founded in 1980 [and I now lead].

In June 2015 the society tested its own crowdfunded, flight-by-light spacecraft, LightSail1.

As this article goes to press, we're preparing for the scheduled autumn launch from Cape Canaveral of its successor, Light-Sail2, to be vaulted into Earth orbit on the SpaceX Falcon Heavy rocket.

The honor and serving of latest Operational Research on Space  to continue, regularly. The World Students Society thanks author and researcher Scientist Bill Nye.