Solar Powered

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Solar Powered
by Larry Klaes

Reproduced from the Ithaca Times, Volume 26, Number 4, September 24, 2003, by permission of the author

For centuries, the oceans of the world were traversed by countless numbers of ships. The majority of these water vessels were powered and moved by the same source: wind. These ships would capture this freely available natural energy from our planet's atmosphere with their great billowing sails and use it to roam the Seven Seas. The advent of steam power in the 19th century, followed by diesel and even nuclear engines, eventually reduced most sailing ships to the ranks of pleasure vessels and specialized craft.

High above, in the vast seas of space, a reversal of history is about to take place.Since the advent of the Space Age with the launch of the Soviet satellite Sputnik 1 on October 4, 1957, virtually every vessel sent into the heavens has been propelled by engines that had to take their own fuel with them, be it chemical, electric, or nuclear. While this was both required and desired in those early years, a small but growing number of pioneers in the field have dedicated themselves to exploring the universe with a power source more reliable and free than the winds of Earth: sunlight.

Soon a craft named Cosmos 1 will become known as the first vessel in human history to move through the skies powered only by the pressure of the light from the Sun. This space event will be "equivalent to the Wright Brothers flight" of the first heavier-than-air powered craft nearly a century ago this December 17, says Ann Druyan. She is program director for Cosmos 1 and CEO of Cosmos Studios, a science education company based in Los Angeles and managed from Ithaca.

Cosmos Studios is the main sponsor for the mission, which is working in collaboration on this historic project with The Planetary Society (TPS), based in Pasadena, Ca. TPS is humanity's largest private space interest group, dedicated to supporting space exploration and the search for extraterrestrial life. The society was co-founded in 1980 by Ann Druyan's late husband, Carl Sagan, professor of astronomy at Cornell University and famed science figure.

The Long Road to Solar Sailing

In the 1870s, the Scottish physicist James Clerk Maxwell discovered that light consists of "packets" of energy composed of very small particles we now call photons. These photons have only a tiny amount of mass, but they can still interact with other matter.

The photons generated by the Sun are constantly spreading out into space in huge numbers at a speed of 186,282 miles per second (at that velocity, a photon could circle Earth at the equator over seven times in that one second), where they exert a force upon any objects they strike and bounce off of.

Though the energy from these encounters is quite minute, the huge amount of photons streaming from our yellow dwarf star builds up momentum over time. Eventually, these light particles can push an object like a solar sail at respectable speeds. The concept of a virtually limitless power source for spacecraft that would only increase vessel velocity over time was quite appealing to both space scientists and science fiction authors.

The first modern notion of solar sailing began with a brief speculation by the great French science fiction author of the 19th century, Jules Verne - no doubt based on the work of Maxwell. In the 1920s, Russian rocket pioneers Konstantin Tsiolkovsky and Fridrickh Arturovich Tsander became the first scientists to study and write about solar sails for interplanetary travel. The idea was revived again in the 1950s and 1960s thanks to the efforts of a new generation of scientists, engineers, and science fiction writers, including Arthur C. Clarke with his famous 1964 story "The Wind from the Sun," about an international manned solar sail race to the moon.

By this time, NASA began to take solar sails seriously enough to conduct some studies on the subject. In the 1970s, solar sail propulsion was considered for a proposed robotic mission to one of the most famous comets of all, Halley, which would be making its closest approach to Earth's vicinity in 1986. However, the technology for solar sailing was just not ready at the time. The comet probe's primary propulsion was changed to ion power, but eventually the entire project was cancelled in an attempt to save money.

Through the rest of the 20th century, more space advocacy groups were formed with plans to make solar sailing a reality. One of these groups was The Planetary Society. In 2000, TPS joined forces with the newly-formed Cosmos Studios to turn their own solar sail project into what has become the Cosmos 1 solar sail mission.

Druyan says she has a "huge respect" for The Planetary Society and its executive director, Louis Friedman, who is also project director for Cosmos 1 and a long-time advocate for solar sailing. Thanks to the opportunity provided by the two groups working together, they were given "a chance to take a baby step to ride a light to the stars."

Turning Swords into Spacecrafts

Being the first celestial vessel propelled by sunlight is not the only notable achievement of the Cosmos 1 project. The satellite has also taken on the important tangible symbolism as an instrument for peace and knowledge born from the war machinery of an era that once threatened to bring down our entire civilization.

One current technical drawback to solar sails is that they cannot launch themselves from Earth's large gravity well. Chemical rockets are still the chosen method to reach outer space from our planet's surface.

In the case of Cosmos 1, there has been a wonderful benefit from requiring an "old-fashioned" boost: The lifting vessel - a modified submarine-launched intercontinental ballistic missile (ICBM), once among the deadliest of weapons in the Cold War - will carry not a nuclear warhead that could have killed millions. Instead, it will hold a satellite that could pave the way for humanity to literally expand into the Milky Way galaxy and beyond.

Druyan describes the situation: "We have converted a weapon of mass destruction into a new way to explore the universe. We are so proud to have the opportunity to do this."

To further the spirit of international cooperation, along with the means to keep the mission relatively inexpensive as space projects go (just four million dollars, including parts purchased from Radio Shack), Russia's Babakin Space Center in Moscow was contracted to build, launch, and operate Cosmos 1. The two superpower nations that once tried to outdo each other in the heavens for geopolitical prestige are now reaping the rewards of cooperation through the Cosmos 1 project.

The missile class to be used for sending Cosmos 1 into space is called Volna. Since its original purpose was to deliver bombs to the United States - in other words, the missile needed to travel only part of the way around the globe - the Volna was given a third rocket engine known as a "kick stage" to ensure that the solar sail satellite reaches an initial polar orbit almost five hundred miles above Earth.

As with many new rocket designs, for a while the Volna's success was in question. A deployment test of the Cosmos 1 solar sails was launched on July 20, 2001 from a Kalmar class submarine named Borisoglebsk in the Barents Sea near the Arctic Circle. The mission ended in failure when the payload did not separate from the kick stage. The test vehicle disappeared near the Kamchatka peninsula and was not recovered. The same thing happened again with another Volna several months later during an unrelated space launch attempt.

Thankfully fate turned for the better in early August when a complete test of the launch system was conducted in a large vacuum chamber. This time the explosive bolts holding the Volna kick stage to the payload section released as designed, leaving the Cosmos 1 team much more confident about a successful launching of the satellite in early 2004. (The original launch date was set for late October, but the Cosmos 1 team pushed the date back to have more time for last minute preparations.)

Since they scrapped the October launch date, the team will wait until early 2004 to loft Cosmos 1 into space, due, ironically, to actions by the former Soviet military. The Russian Navy will be conducting operations in the Barents Sea in November and December, barring all civilian activities from the area for the last two months of this year.

The Mylar Flower of Space

The Cosmos 1 spacecraft is a seeming contradiction in terms of the varying sizes of its parts: Its eight fanlike sails, when fully opened in Earth orbit, are almost 100 feet across and encompass a total acreage of 6,415 square feet. Yet the main bus of the satellite, its "brains" and "heart," is only one yard in diameter, weighs just 88 pounds, and receives its power from two solar panels.

The sails themselves are composed of aluminized Mylar much thinner than plastic food wrap - a necessity since the pressure from the Sun's photons is no heavier than that of a postage stamp resting in the palm of your hand. On Earth's surface, Cosmos 1 would be impossibly fragile to use as a sailing vessel, but in open space, when the gravity is negligible, the solar sail ship will be able to make many circuits of our globe and change its polar orbit altitude by hundreds of miles.

Cosmos 1's mirror-like sails should be visible to most people on Earth at night as a very bright "star" moving silently among the stars. "A new light in the sky," says Druyan. "Here's a way to invigorate a whole new way to explore space," she adds, for each evening the stellar presence of the solar sail will enlighten and remind the human species to the fact that short-lived rockets are not the only answer to obtaining the heavens.

On this first venture into space for a solar sail mission, the main payload of Cosmos 1 consists only of two sets of experiments: cameras and accelerometers. A Russian and American camera system will image the satellite as it opens its magnificent sails "like a great reflective flower," says Druyan. Cosmos 1's cameras will also take images of Earth and the accelerometers will measure how fast Cosmos 1 is moving due purely to pressure from the impacting photons.

Druyan sums up the main purpose of the Cosmos 1 mission: "If we can prove solar sailing is possible using only light, we will have accomplished quite a bit and be very happy."

Cosmos 1 also carries a compact disc containing a "Letter to the Future" from Druyan, an essay on the history of solar sailing by Louis Friedman, the historic technical paper on the concept by F. A. Tsander, and several early science fiction stories about solar sails, including the famous "The Wind from the Sun" by Clarke. You can read the complete contents of the CD on this Web site: www.planetary.org/solarsailcd/

Riding a Beam of Light

Should the initial tests of Cosmos 1 go well, there may be an attempt to move the satellite with a ground-based laser beam. This concentrated artificial light will give solar sails the extra boost and control they will need for future missions in deep space where the influence of the Sun is diminished.

Solar sails are quite slow in the initial phases of their flights: It would take Cosmos 1 over one year to reach the moon, while the manned Apollo missions using conventional rockets made it to Earth's natural satellite in just three days.

If Cosmos 1 were aimed to leave our planetary system, using sunlight alone it would eventually obtain a velocity of 62 miles per second, passing the orbit of Pluto in just five years. Cosmos 1 would quickly overtake the probe Voyager 1, which has taken 26 years to reach its current record distance of 8.3 billion miles from Earth. The solar sail would "leave Voyager in the dust," says Druyan.

Powerful laser systems located in space could one day provide a way for future solar sail missions to explore not only the other worlds in our Solar System, but to depart our celestial neighborhood and visit other star systems. A laser-powered light sail could reach the nearest suns in a matter of decades.

By comparison, the Pioneer and Voyager probes will require over 80,000 years just to cover the distance to the nearest star system, Alpha Centauri, which is 4.3 light years (25 trillion miles) from Earth. Already the two Pioneer craft have gone silent and the Voyagers will likely follow suit by the year 2020, long before any stars can be reached.

Humanity's first interstellar probes may enter the galaxy wearing gigantic sails of incredible thinness and riding on a beam of light. And perhaps our first visitors from the stars may enter our system by a similar means of transportation.

Sailing into the Cosmic Ocean

One day, if it lasts long enough, Cosmos 1 may be recovered by a spaceship crew that comes upon this relic from the early decades of the Space Age. On board the ancient vessel they will find the CD meant as a message to their time and beyond.

Imprinted on the CD itself is a quote from Carl Sagan, taken from an episode of his and Druyan's epic television series Cosmos, which premiered on PBS in 1980. In this one sentence, Sagan explains to our descendants why their pioneering ancestors sent this beautiful craft into space: "We have lingered for too long on the shores of the cosmic ocean; it's time to set sail for the stars."

Should Cosmos 1 succeed in the purpose of its mission, the spaceship that may one day find it will be powered by light.

To learn more about the Cosmos 1 Solar Sail Mission, visit the official Planetary Society Web site at www.planetary.org/solarsail.

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