https://en.wikipedia.org/wiki/Solar_sail
Solar sails (also called light sails or photon sails) are a method of spacecraft propulsion using radiation pressure exerted by sunlight on large mirrors. A number of spaceflight missions to test solar propulsion and navigation have been proposed since the 1980s. The first spacecraft to make use of the technology was IKAROS, launched in 2010.The momentum of a photon or an entire flux is given by Einstein's relation:[14][15]
p = E/c
where p is the momentum, E is the energy (of the photon or flux), and c is the speed of light. Specifically the momentum of a photon depends on its wavelength p = h/λ
https://en.wikipedia.org/wiki/Radiation_pressure
Radiation pressure is the mechanical pressure exerted upon any surface due to the exchange of momentum between the object and the electromagnetic field. This includes the momentum of light or electromagnetic radiation of any wavelength which is absorbed, reflected, or otherwise emitted (e.g. black-body radiation) by matter on any scale (from macroscopic objects to dust particles to gas molecules).[1][2][3] The associated force is called the radiation pressure force, or sometimes just the force of light.
Here is where things don't seem to add up
Basically, a photon has momentum. If it is reflected by a mirror, then its momentum is reversed. (See diagram above) As momentum must be conserved, the mirror has absorbed twice the momentum of the photon (Photon incident-ed normal i.e. perpendicular to the mirror in my explanation)
But how can it gain momentum when energy must be conserved.
Imagine a perfect reflective mirror. When light is reflected, no photons are loss. And we have never observed a red shifted mirrored image. That is, you look the same color as your reflection. Thus for ideal case, no energy is loss by the photons, so the mirror should never gain energy. However, I do agree that momentum is conserved. I do not know how to explain this phenomena. Perhaps a type of mass-less momentum artifact is passed through the mirror. Perhaps the mirror does move slightly, and in such a slight red shift in the reflected image occurs (for a free mirror). In any case, the current math to explain this does not completely add up
The radiation pressure phenomena does exist though. Einstein has done some work on it (Photo-electric effect) Also in e=mc², he used a though experiment where the photon was fully emitted from one side of a box and fully absorbed by the other. I think a greater momentum transfer occurs when the photon is completely absorbed by a dark material as opposed to a reflective material. And when light passes though something "thick" permittivity-wise like glass or even diamond, the diamond gets the momentum of the photons that are inside the diamond and then the diamond "allow out" the photon, and looses it kinetic energy and momentum and passes it to the photon when it emerges from the diamond.
The Optical Tweezers uses bent light rays
https://www.youtube.com/watch?v=XjXLJMUrNBo
Also, experiments have shown that the direction of the momentum component of Light is in the same direction as the direction that the light is travelling. See Compton scattering
https://en.wikipedia.org/wiki/Compton_scattering
(Basically the reflected light was red shifted, and the angle of reflection was correlated with the amount of red shift or momentum loss)
(Einstein's Photoelectric effect)
https://en.wikipedia.org/wiki/Photoelectric_effect
Let's look at some classical momentum physics using billiard balls of different masses.
Two balls collide with perfect elasticity. Or rather one ball is stationary and another ball collide into it. As you vary the mass of the balls, you will observed that perfect transfer of momentum, and energy, occurs when both balls have equal mass. This is actual a form of impedance matching which Tesla was brilliant at (Electrical circuits have sometime similar to mass). Recall Newton's cradle
https://en.wikipedia.org/wiki/Newton%27s_cradle There is perfect momentum transfer and energy transfer. It does not matter the velocities of the balls. If they travel at different speeds and collided then the momentum would behave as if the balls pass through each other. Ball A would give all its momentum to Ball B, and Ball B would give all its momentum to Ball A. They exchange momentum. This would look cool on newtons cradle (Lift both ends at same time but with different heights).
Now let one of the ball be the size and mass of the earth and the other ball be the size and mass of a tennis ball. (Ignoring gravity) If an astronaut tosses the ball at the earth, you would expect the tennis ball to just bounce back at the astronaut without displacing the earth much. The energy transfer (efficiency) is extremely low. The tennis ball still has virtually all of its initial kinetic energy. This is bad impedance matching. Now there are ways to have better matching. Suppose you could have a billion tennis balls. And together they have the mass equal to that of the earth. And it was possible to toss all the balls simultaneously. This is similar to Tesla's resonance. It must be simultaneous. During a collision, there is a time when kinetic goes to potential. Deceleration occurs, then acceleration occurs. These changes must occur simultaneously like they are in phase to have a maximum in the superposition. Then the energy transfer will be ideal. And the tennis balls will move the earth by passing all of its kinetic and momentum. In this case energy is important.
Normal collisions have loss in energy. Basically not simply billiard ball with one potential energy level. Normally the mechanism is complicated. And has many various energy levels. Energy is lost because it has more ways in which the energy can flow. (And its does not stay in the primary potential energy.)
See a attached xls file to play around with. It does the calculations of repeated hitting a 300 unit mass body m1 with another body m2 which has 1 unit of mass. The idea is to increase the velocity of m1 more and more be repeated collisions. And
https://www.omnicalculator.com/physi...on-of-momentum
Now back to a solar sail with mirrors that collect momentum but inefficient at energy.
If the sail has a dark area, energy and momentum is absorbed. It could be a solar panel. (Yes the mass is much greater that a foiled mirror) Photons would be absorbed (Analogous to collision when ball stops). Some goes to electromotive force and some to heating (vibration of atoms). The photons that heat contribute to a net momentum change. Then the electromotive force is pass to a laser booster. Still a work in progress. (As this is a more complicated energy path it may be more analogous to a type of elastic collision) The solar panels could be stowed like a real sail ship and all of that
LightSail 2
https://en.wikipedia.org/wiki/LightSail#LightSail_2
A laser beam from earth can be used to push a light sail that is in outer space.
https://en.wikipedia.org/wiki/Beam-powered_propulsion
Attached xls
https://anonymousfiles.io/waPLBRBY/
md5 8fade48f2af57ef920cae01525c9fc66