Countdown To A Solar Sail

February 27, 2001 / 1:31 PM EST / AP

Forget bulky rockets and costly fuel: A U.S.-Russian consortium plans to send a craft skyward that floats, not on the wind, but on the gentle pressure of the sun's rays.

The group hopes that solar sails can be used to boost or decrease the orbits of spacecraft, travel between the planets and someday even take humans to worlds around other stars.

Backers of the privately funded project hope a 30-minute suborbital test flight set for spring will show that a tightly packed solar sail can unfurl like an enormous kite in space.

A second, more ambitious mission will follow in October, when the group sends a larger version on what it hopes will be a voyage around the Earth.

"We'll count ourselves as successful if we fly even a short time in that mode," said Louis Friedman, manager of the Cosmos 1 project.

"The Wright brothers flew for 12 seconds and they had a successful flight. If we can fly not 12 seconds but 12 minutes, 12 days or 12 weeks, we'll be happy,"

The sail uses solar pressure in the same way a sailboat uses the wind. It consists of a large sheet of reflective material and a framework of inflatable girders to keep it extended.

The advantage is the same boasted by the sailboat: There is no need to carry much fuel, which can be expensive to launch into space. Small blasts from thrusters adjust the sail's trajectory.

When the sun's energy hits the surface of the solar sail, the particles, or photons traveling at the speed of light provide continuous thrust that can be increased or decreased depending on the sail's relationship to the sun.

A converted intercontinental ballistic missile will send both missions aloft from a Russian nuclear submarine in the Barents Sea a relatively inexpensive option that has kept the project's budget to $4 million.

Cosmos Studios, a science-based entertainment company founded by Ann Druyan, widow of the late astronomer Carl Sagan, and Joe Firmage, a Silicon Valley entrepreneur and sometimes UFO investigator, are footing the bill.

"We are proud to be a part of this historic mission, which is a critical baby step to the stars," said Druyan, Sagan's longtime collaborator.

The spacecraft is being built by the Babakin Space Center in Russia, while the Makeev Rocket Design Bureau has built the launch vehicle. The Space Research Institute of the Russian Academy of Sciences is also a principal contractor.

The benefits of solar sails could be enormous: Cosmos Studios says the sails could theoretically attain speeds 10 times greater than NASA's Voyager I and II, which travel at 38,000 mph.

The American and European space agencies, and at least one private company, hope that future missions can rely on this high-tech and comparatively low-cost technology.

"If the Planetary Society mission is successful, it will be very useful to NASA," said Hoppy Price, manager of solar sail technology development at the National Aeronautics and Space Administration' Jet Propulsion Laboratory.

Last year, NASA said it wants to launch an interstellar probe powered by space sails by 2010. The sail, spanning 440 yards or twice the diameter of the dome at the Louisiana Superdome, would be the largest spacecraft ever built, the agency said.

Solar-driven spacecraft will be slow to accelerate, but with time should reach velocities that will make travel across great distances possible.

"It allows you to travel, come back and go out again because you don't have to refuel," Price said.

The April launch will test the deployment of just two petal-shaped blades of Mylar polyester film. At the end of the brief flight the sail about one-fifth as thick as a garbage bag will fall to Earth.

For the orbital flight later this year, a larger eight-petal design will be launched. Inflatable trusses will pull the sail from a canister and become rigid to support it. Each of the triangular petals can be turned to steer the spacecraft, allowing it to tack like a sailboat.

"The goal is to be the first solar sail flight," said Friedman, executive director of The Planetary Society, a space advocacy group.

The orbiting spacecraft will gradually spiral away from Earth as sunlight pushes on the 720-square-yard sail. The 88-pound craft will carry two cameras and several instruments and should appear in the night sky as a point of light as bright as the full moon.