Forty years ago this was a good idea, today it has happened

Wednesday, May 20, 2015, 9:21 AM - Nearly 40 years ago, astronomer Carl Sagan went on the Tonight Show to discuss a fantastic new technology that could one day take us to the stars. Now, courtesy of The Planetary Society's LightSail-1 mission, his dream has taken flight.

At 11:05 a.m. ET today, Wednesday, May 20, an Atlas V rocket lifted off from Cape Canaveral, Florida, carrying a secretive, uncrewed Air Force space plane into orbit.

Along for the ride on this launch was a small spacecraft, roughly the size of a fire extinguisher, named LightSail-1. This breakthrough mission has been at least four decades in the making, and will take a very old means of transportation and exploration, the sail, and update it to the 21st century.

Coverage of the launch began at 10:45 a.m. ET, streamed live over the web by United Launch Alliance, and at exactly 11:05 a.m. ET, the rocket and its precious cargo blasted off for space.

Once in space, it was just a matter of waiting until confirmation was received that the spacecraft had successfully separated and was flying free, which happened right on schedule:

Bill Nye, the Science Guy, who is the CEO of The Planetary Society, spoke briefly after the launch in a press conference:

"Today is an extraordinary day for The Planetary Society, our members, and space enthusiasts around the world: LightSail successfully launched into orbit. Our co-founders dreamt of this day. We've been working to get a solar sail into space since I joined The Planetary Society Board in 1997.
"While we celebrate this step, LightSail’s biggest tests are still ahead. Over the next days, we will be monitoring our CubeSat as we prepare for the big show: the day LightSail deploys its super shiny Mylar sails for flight on sunlight. Stay tuned; the best is about to happen.
"As we await that stage, we just get more excited. After all, we've been working on this for 39 years. LightSail would not be possible without our members, fans and citizens worldwide. We are all in this together. Let's see if we can give space exploration a strong nudge and change the world a little bit."

Many spacecraft over the years have used the Sun's rays to power their systems and instruments. LightSail-1 goes one step beyond that, however, to harness the Sun's rays as a direct means of propulsion. Once in space, LightSail-1 will unfurl a large sail - a solar sail - which will propel the spacecraft simply by the pressure exerted by sunlight.

Bill Nye explains the concept below, with the help of his mentor, Carl Sagan:

The benefit of a solar sail, compared to other kinds of spacecraft propulsion, is that it doesn't require the spacecraft to carry fuel. This makes the spacecraft lighter, thus easier to launch, and it makes the spacecraft's mission nearly limitless. As long as the spacecraft can aim the reflective side of its solar sail at the Sun, it can continue to operate - drawing in power for its instruments and propelling itself through space.

Also, since the radiation pressure from sunlight is constant, this can provide a constant source of propulsion. It would take the spacecraft some time to build up speed this way, but some future "space clipper ships" could be the fastest spacecraft we've ever built, carrying us beyond our solar system.

Sources: The Planetary Society | United Launch Alliance | The Planetary Society

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