Solar Sailing

[Mouse]

Hey I wanted to ask about Solar Sailing and I find this strange and I am quite puzzled as how can mere sunlight power an aircraft.

 

I have looked thru articles on Solar sailing available to me at the moment but I dun get how can sunlight power a spacecraft. is it like solar cells or using light energy

[Klaynos]

Photons have momentum:

 

p=hf/c

 

So when a photon is absorbed or reflected the law of conservation of momentum means the object doing the absorbing/reflecting must change momentum. This is a very very small amount but in space with little friction and with direct sunlight this is enough to create a usable acceleration.

[vordhosbn]

But isn't it more likely for the solar sail to heat up to vaporization, rather than be accelerated by the solar wind?

[Klaynos]

But isn't it more likely for the solar sail to heat up to vaporization, rather than be accelerated by the solar wind?

 

No, you design the sail so that doesn't happen, if you are reflecting the light the heating is very small and easily deal able with.

[Mouse]

So it's like when the sails are facing the sunlight, it will be like a sail on a ship and it will move the space craft?

 

It will have to face the sun all the time right?

[vordhosbn]

...

It will have to face the sun all the time right?

Does a sailboat needs to travel always to the direction of the wind?

[Mr Skeptic]

The sail will face roughly in the direction of the sun. You can change the angle depending on what direction you want to be accelerated. The craft can be moving in any direction regardless of how you angle the sail.

[Mouse]

So that's means the mirrors or sail have to face the sun to get the "wind" to propel it?

 

What happens if say we managed to get as far as Pluto? The ship will be floating in space?

[Mr Skeptic]

There will be a lot less propulsion the farther you get from the sun.

[Mouse]

I see so a laser propulsion station will be necessary then? How long will it take using solar sailing to get from Earth to Mars?