Its designers call it LightSail-1. And if it works as advertised, the solar sail project would represent a baby step toward humanity's first starship.
Nov 11, 2009 - Pasedena, California, USA - Four years after its first solar sail ended up in the...
Nov 11, 2009 - Pasedena, California, USA - Four years after its first solar sail ended up in the ocean instead of orbit, The Planetary Society announced Monday that by the end of 2010 it will try again to launch a spacecraft that will be propelled by the subtle pressure of sunlight. LightSail-1 is envisioned as the first of a trio of solar sail craft in a project boosted by an anonymous $1 million donation, according to the space advocacy organization co-founded by the late astronomer Carl Sagan. Solar sails are theorized as a way to achieve long-duration interstellar flight. A solar sail would be propelled by the pressure of light photons pushing against a surface not the stream of ionized gas known as the solar wind. The spacecraft would accelerate very slowly but eventually reach tremen
(newscom.com)
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This week, the California-based Planetary Society announced a new project to launch a small spacecraft propelled by a solar sail. In principle, the idea is simple: Use the sail to intercept sunlight, which presses on the sail much like wind on canvas. (The same pressure keeps the sun from collapsing under its own gravity.)
Initially a solar-sail craft builds momentum almost imperceptibly. But with no friction in space to resist its motion, the craft in theory should go faster and faster, as long as there is enough light to propel it. It requires little on-board fuel for course corrections, since the sails can be "trimmed" to change course, just as a sailboat's canvas is trimmed.
This is the one known technology that can get up to the speeds as you leave the solar system "that make interstellar flight not completely ridiculous," says Bruce Betts, director of projects for the Planetary Society, which is undertaking the $2 million demonstration effort.
First, however, the craft needs to reach space – the toughest part of any solar-sail project.
Planetary Society's First Solar-Sail Project Failed
This is the Planetary Society's second try. Its first attempt in 2005 ended up in the Pacific Ocean when the first stage of a Russian submarine-launched missile carrying the group's Cosmos 1 solar-sail satellite misbehaved.
Last year, the National Aeronautics and Space Administration (NASA) attempted to launch its version of a solar-sail demonstration satellite. It hitched its satellite to SpaceX's – the American space transport company – Falcon 1 rocket. That rocket also failed to deliver the craft to orbit.
Undaunted, the Planetary Society is pressing ahead. And while LightSail-1 is the group's main focus, it envisions this as a three-stage program.
LightSail-1 is designed to orbit some 800 kilometers (roughly 500 miles) above Earth. At that altitude, the craft orbits above the last vestiges of Earth's atmosphere, which introduces friction and so can slow the craft faster than sunlight can accelerate it. The LightSail-1 team hopes to test a solar sail's ability to steer the craft by changing the trim to adjust the craft's orbit.
