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
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
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
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
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:
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
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