Hey hey, Bill Nye here at The Planetary Society talking about solar sailing.
Most spacecraft get pushed through space with some kind of rocket fuel.
The momentum of the fuel going this way pushes the spacecraft that way. Take a look.
Now, if I had been in space I would have drifted away.
There are a few different types of fuel that are used in space travel, but they all come out of an
onboard fuel tank. So they all eventually run out of gas, if you will.
And when they do, that's it. They're done. No more propellant means no more push.
(crying) No more push!
But a solar sail spacecraft like this one doesn't need ordinary rocket fuel.
Instead it gets pushed through space with a free supply of energy.
The pressure of light.
Light is made up of particles we call photons. Imagine this ping-pong ball
is a photon. A single particle of light. Photons weigh nothing they have no mass.
But they still have momentum. If we have a spacecraft that's low enough mass
and big and reflective enough then photons can give it a little push.
Each photon imparts just a tiny bit of momentum, but the Sun pumps out
billions and billions of them every second!
Now, imagine this happy cookie sheet is the reflective sail of a spacecraft.
It gets a push through space!
In the vacuum of space it really works.
Solar sailing is a game-changer. These spacecraft can be steered a lot like sailing ships at sea.
They can be pushed away from the Sun or turn and tack toward the Sun.
Someday soon we could be sailing around the solar system with the unlimited energy of sunlight.
And maybe one day in the future we could even sail one to another star.
But of course one test is worth a thousand expert opinions, so we at
The Planetary Society are going to fly our LightSail 2 spacecraft and learn more
about actual flight by light. You might think that a spacecraft has to be a huge
thing made with a lot of money from a big government agency, but LightSail is
a small rectangular box of a satellite called a CubeSat.
And it was crowdfunded by amazing everyday people who are inspired by space exploration.
Like this guy!
Huh? Me?
Yes you! Or if you contributed or pitched in to our Kickstarter campaign
or if you're a Planetary Society member, this is your spacecraft.
Over 40,000 human peoples made this
project happen.
And there was one dog.
So thank you!
Back in 2015 we flew LightSail 1. It was a test flight
in a pretty low Earth orbit. The mechanics of the spacecraft worked and
we even snapped the stunning photo of the sail in space. It's beautiful!
And soon LightSail 2 will ride on a SpaceX Falcon Heavy rocket.
We'll go to a higher orbit and do some more complex maneuvers. The shiny sail will be visible
from here on earth for about a year. The descendants of LightSail 2 may one
day travel to the stars. If I may..
how cool is that!?
LightSail 2 will be pushed by sunlight!
