Cosmos 1: To Sail the Celestial Seas

Solar sailing is a most romantic vision of space travel: spacecraft plying the solar system or interstellar space by means of enormous, microscopically thin sails that harness the pressure of light itself—whether sunlight or a laser or microwave beam aimed from afar into the sail. Although the thrust generated by photons bouncing off the reflective material of a solar sail is so minute that it can only produce very modest acceleration, it can be sustained over long periods, so that solar sailboats--which do not need to carry their own fuel--can in time build up enormous velocities. “Solar sailing is the only technology we know today that is the pathway to the stars,” said Louis Friedman, Executive Director of the Planetary Society, at a Hayden Planetarium lecture on March 24 titled “Cosmos 1: Reaching for the Stars.”

In his presentation, Friedman described the Cosmos 1 project, the Planetary Society’s prototype solar sailboat, which it hopes to launch in late 2003 in cooperation with Russia’s Babakin Space Center and the Russian Academy of Sciences’ Space Research Institute. The project is funded by Cosmos Studios, a science-based media venture run by Ann Druyan (Planetary Society co-founder Carl Sagan’s widow), the A&E Network, and Planetary Society members, and is the first space mission by a public-interest organization without government funding. Cosmos 1 is to be launched into an 800-kilometer circular, near-polar orbit of Earth. The sail is composed of eight rotating triangular blades, made of 5-micron-thin aluminized reinforced Mylar, with a total area of about 600 meters.
The primary objective of the mission, which should last about a month, is to demonstrate control over the spacecraft and its sail, and to gradually increase its distance from Earth. Two other experiments may be attempted. One is to illuminate the sail with a microwave beam from an Earth-based radar, and measure the acceleration on the spacecraft. This would demonstrate microwave sailing—a possible means of advanced sailing like laser sailing that could someday lead us to the stars. The second will measure the ion flow around the spacecraft. Cosmos 1 will carry several cameras, an accelerometer, and other instruments.


“There’s a swords-into-ploughshares element to the project,” says Friedman. The Russian Volna rocket that will carry the 100-kilogram Cosmos 1 into orbit is a converted Soviet-era ICBM to be launched from a submarine in the Barents Sea north of Murmansk.

In a suborbital test on July 20, 2001, Cosmos’s solar sails failed to deploy because of problems during the test vehicle's separation from the rocket. In July 2002, a European payload failed to separate properly from its Volna launcher during another sub-orbital flight. The problem was a premature separation of the payload while it was still inside the second stage of the rocket. A failure commission set up by the Russian space agency concluded that the cause of the 2001 and 2002 problems was most likely the same, the result of a design change made when the Volna was converted to a peaceful civil payload launcher. Correcting the problem should be relatively simple, but the test program to verify that it is correct is not. The Russian space agency is demanding an extensive series of ground tests, to be conducted by the Makeev Rocket Design Bureau in Miass, Russia, which is responsible for the Volna launch vehicle. The Volna has been grounded until changes to the payload separation system can be implemented and thoroughly tested, hopefully before the end of 2003.

If successful, Cosmos 1 will be the first flight of a solar sailship in space. The Planetary Society and its partners hope that this limited mission will inspire others to advance this technology so that lightships can ferry humans between the planets and, perhaps someday, to the stars. Outside the inner solar system, though, the Sun’s energy is too weak to effectively propel a spacecraft. A solution would be to aim a laser or microwave beam—which would remain coherent over great distances—into the sail. To this end, lasers could be placed in orbit, alongside power stations harnessing the energy of the Sun; the excess power could be transmitted back to Earth to be used as energy.

In addition to his overview of Cosmos 1, Friedman also discussed the Planetary Society’s mission as an advocate for the peaceful exploration of our solar system and the search for extraterrestrial life. Founded by Friedman, Sagan, and Bruce Murray in 1980, the Planetary Society ( http://www.planetary.org ) is a nonprofit, nongovernmental organization, funded by dues and donations from individuals around the world. With more than 100,000 members from over 140 countries, it is the largest space interest group on Earth. It helps fund many of the projects involved in SETI, and was instrumental in getting SETI@home up and running. It is involved in several Mars projects, including the two Mars Exploration Rovers, due to be launched within the next few months for arrival at the Red Planet in 2004. It has funded and advocated search programs for near-Earth objects, as well as efforts to find extrasolar planets.

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