LIGHT SAILS:

I have not done the maths involved , I have just considered the light sails mass compared to the Earth's and considered that if light had the force to move the light sail away from a gravitational force, that would show that light has the strength to apply a force that was greater than the gravitational force. I suppose we will just have to wait for the outcome of the light sail test.

 

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This thread seems to have gotten way off the light sail....

Using a light sail if you want to move out in the solar system you orient the sail, such that it speeds up your orbital velocity. If you want to move in toward the sun you position it so that it slows down your orbital velocity.

Where did the idea of shutters come from? A spaceship, satellite or probe using a light sail needs to weight as little as possible. And for very long journeys maybe even have a backup sail... Other than that you would guide it much as you would steer a parachute, by angling it to provide thrust in a direction that will change your course as desired.

To stop.., close or cut loose the sail and gravity will do the job for you.., which hopefully will just put you into a stable orbit.

 

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What you are not considering is the difference in mass of any light sail satellite/probe/spaceship and the mass of the earth... And the fact that with a light sail you could change its orientation to change how it affects the satellite/probe/spaceships velocity. You cannot do that with the earth.

 

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In other words you've simply not bothered to look at the facts and assumed (without thinking) that you have a valid point.

The test is to see whether or not the idea is practicable.
We know for a fact that propulsion will occur, the question that's being tested is: will the control systems work correctly? - quote from the article: The mission will test LightSail's critical functions.

 

You say you no for a fact that propulsion will occur, propulsion by light or propulsion by the solar winds?

 

Clue: it's called a LIGHTsail.

 

If it is a sail then the solar winds will effect it?

How will they know it is light making the momentum?

How can it work without the gas present that is involved in the Crookes device?

 

Different things:
http://en.wikipedia.org/wiki/Solar_sail
http://en.wikipedia.org/wiki/Solar_wind
http://en.wikipedia.org/wiki/Electric_sail
http://en.wikipedia.org/wiki/Magnetic_sail

 

Light sails have already been tested and have passed. A Japanese effort from memory.

http://www.space.com/8748-solar-sail-passes-big-test-deep-space.html

 

Because it's not a Crookes device?

 

How about a rotating solar sail?* it has been patented. Photons are absorbed on the day side and and are re-radiated ( producing mini-thrust) during the evening/night portion. The "sail" is empty in the cool mornings, and re-charged with energy during the day portion. All planets except Venus and Uranus are pushed along their orbits that way, minuscuely. If you don't want to translate, stop spinning in the sun.
*the spatial equivalent of the Flettner Rotor. and
Bodies that rotate and expel not just photons, but expanded matter jets, will translate even more efficiently; think Comets.

 

It was said in another thread that without the gas in a Crookes device that the rotation/force of the light does not do anything, so how can it work without this gas? to me the experiment will consist of the solar winds pushing the sail along and the light will do jack.

 

One uses one effect and the other uses a completely different effect. Radiation pressure is very weak and the Crookes device spins much faster than radiation pressure could make I (and in the opposite direction, iirc).

 

They have made a sail, the force of the solar winds will be greater than the force of light, the solar winds will move the sail reducing any possible force that light had on the sail.
The light will have no effect and even if it did, there would be no possible way to distinguish whether it was light or the solar winds making it move, a bit of uncertainty principle before they even have lift off.
I have read that this venture was by private investors, they have been duked in my opinion.

 

Unless, of course, the designers utilized their brains and calculated the effects!

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Oi vey...

TC - are you familiar with this device...

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A Crookes Radiometer...

It is an airtight bulb with a partial vacuum inside. The vanes are white or light coloured on one side, and black or dark coloured on the other.

Do you know what happens when light is applied?

http://en.wikipedia.org/wiki/Crookes_radiometer#Thermodynamic_explanation

I realize this is not the principle behind how the solar sail works... but understanding this will go a long way to understanding the solar sail.

 

Yes I understand the idea behind it, I see it differently slightly of cause like normal. I see that one side been reflective and one side being absorbing does have an effect on the thermodynamics of the opposite properties, but at the same time I see the force of light pushing it around, one side being of no resistance and one side opposing the lights force that creates more force on the one side created motion.
A black body being maximum propagation and maximum pressure of force by the propagation.

P.s I am surprised these are not giant windmills in the day time.

 

No, you really don't understand the idea behind it. If you had a little self-awareness of how bad you are at figuring these things out for yourself, you'd Google them, read about them and learn them. It would be both faster and more effective.

The black side receives LESS force from radiation pressure than the shiny side.

Again, radiation pressure is tiny, so that wouldn't be useful. The windmills we have are quite good at catching the wind.

 

I would argue it was the other away around, the reflective properties of the silver allow the light to pass and reflect at a quicker rate, where as the black side absorbs more having a slower reflective rate, meaning a greater force imposed and a greater magnitude.

 

Again: don't argue, learn.