Sailing the solar wind to the stars

Thursday, Dec 4 2003
Photo by Louis Friedman, ThePlanetary Society

THROUGHOUT THE AGES humans have been borne across oceans by the power of wind. Propelled by nothing more substantial than air, schooners and brigantine have ferried men to the farthest reaches of our globe. Now a fantastical descendant of these windblown craft is about to make its maiden voyage, harnessing as its driving force the ephemeral power of light. At the Planetary Society in Pasadena and the Babakin Space Center in Moscow, scientists are developing a sailboat to the stars, a “ship” that will ride the “solar wind” and carry us across galactic seas. If all goes according to plan, this could be the start of a new era in interplanetary, and even interstellar, exploration.

Planetary Society executive director Dr. Louis Friedman likens the Cosmos 1 to the seminal airplanes of Orville and Wilbur Wright. December 17 marks the hundredth anniversary of the brothers’ first engine-powered air voyage near Kitty Hawk, North Carolina, and hence the official centenary of the Age of Flight. Next year when Cosmos 1 is launched, its inventors hope that they will be inaugurating the next phase in mankind’s aeronautical evolution.

Socially as well as technically, Cosmos 1 is a milestone. Launched from a Soviet submarine and built by Russian space engineers, the craft results from a surreal fusion of American capitalism and post-glasnost pragmatism, an improbable collaboration between formerly competing superpowers, each struggling to extend mankind’s reach into space in an era of heavy funding cuts. The whole setup is literally a MOM and POP affair: Mission Operations Moscow will take primary responsibility for launching and monitoring the payload, with backup provided by Project Operations Pasadena. Both are working from small budgets and must dispense with many of the usual formalities, such as trial runs and test flights.

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ON A RECENT AFTERNOON while L.A. burned and the sky took on the pallor of the apocalypse, I visited POP HQ at the Planetary Society’s home on a quiet suburban street near the Caltech campus. Having been schooled in the gleaming theater of the starship Enterprise and steeped in the epics of Isaac Asimov, I had to circle the block several times before it sank in that the rambling, wood-shingled house with the flagstone path and the shading trees was really ground zero for a radical experiment in space propulsion. This was not the Kennedy Space Center.

Inside, the décor retains the unmistakable aura of upper-middle-class ’70s suburbia — shag-pile carpet, lace curtains on the kitchen windows, beige and brown throughout. In the hallway a technician is performing surgery on an aging photocopy machine. Half a dozen of the society’s 20 employees are deployed at desks scattered around what is clearly the former living room and dining room. I am reminded not so much of Star Trek as its endearingly homey spoof Galaxy Quest.

Dr. Friedman, a former Jet Propulsion Laboratory engineer, greets me in the entrance hall, his shaggy eyebrows at one with the hirsute floor covering. A towering bear of a man, Friedman founded the Society in the mid-1980s with Carl Sagan, he of the infamous “billions and billions.” Sagan was a leading proponent of interplanetary exploration, a cause he championed with relentless enthusiasm until his death in 1996. “We have lingered long enough on the shores of the cosmic ocean,” Sagan once wrote; “we are ready at last to set sail for the stars.” Cosmos 1 is the material embodiment of that dream.

For decades, space agencies have known that any serious trips to the stars will require a revolution in propulsion technology. Current spacecraft are driven by rocket power — some kind of fuel is expelled out the back, forcing the craft forward under the inexorable logic of Newton’s Third Law: For every action there is an equal and opposite reaction. The obvious problem with rocketry is that all fuel must be carried on board, which for long journeys becomes impossibly heavy and exorbitantly expensive. In 2001, a NASA report summed up the situation bluntly: “Using current rocket technology,” the engineers wrote, “a trip to the next star would consume the mass-energy equivalent of a planet in order to arrive within a reasonable lifetime.” Some other power source is urgently needed, and remarkably, one possibility is light.

In principle the idea is child’s play. According to quantum mechanics, light is a stream of particles known as photons, so light radiating from our sun must act like a delicate wind. Put a sail in front of this photonic gale and it should be driven forward by a minuscule but continuous pressure. “The whole principle of solar sailing is very low thrust,” Friedman explains. You never get more than a tiny acceleration, but over time in the virtually frictionless environment of space it can build up to enormous speeds. Unlike a rocket-powered ship, a solar sail need not carry a drop of fuel. As the society’s Web site notes, it is “a spacecraft without an engine.”

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