Propulsion for Spacecrafts using on-board Laser Reflection and Absorption

In this paper, a new laser-based, on-board propulsion system has been produced. This system utilizes Laser reflection and absorption to obtain a net momentum. The proposed system is also unique in the sense that no on-board propellant is required. Further, the power consumed can be ideally recycled 100%. This makes it a viable mode of propulsion for long distance trips to planets or solar systems. Further, it has been calculated that depending upon the lasers used, this system can propel a 4000kg spacecraft with an acceleration of 100-10000 ms -2 . This means, a 4000kg mass can be propelled to one-third the speed of light in just 5*10 4 seconds, or 13.8 hours roughly. This is a big jump from current technology, which cannot achieve sub-luminal speeds, that too so quickly. This makes this system of propulsion our best bet for sub-solar system travel. Further, the setup proposed is expected to be improved.


Theory and Setup
The proposed system uses lasers as the mode of propulsion.It uses concept developed and discussed by R.L. Forward in a 1984 paper [1].Proposed setup includes one absorbing surface, an inclined reflecting surface, and another reflecting surface in front of inclined plane, as shown below:

Absorbing Plane
The idea is to plant lasers on one surface which is ideally made of an ideal Laser absorber.Lasers are fired normal to this surface producing force F 1 on surface (actually, space craft) as shown in diagram 1.The lasers are reflected by ideally reflecting inclined plane, which produces a force F 2 on inclined plane, normal to it.
The lasers then fall on third surface, which is again a perfect reflector.This Reflecting surface *E-mail -jiveshadhlakha@gmail.comproduces a Force F 3 normal to this surface.Due to reflection, a force F 4 is again applied on this reflecting surface, which is equal to F 3 .This reflected beam again falls on reflecting inclined surface; again apply a force F 5 perpendicular to surface.
Finally, the lasers reach absorbing surface applying Force F 6 equal to F 1 .The absorbed lasers are again converted to electric potential and stored in batteries.This all is illustrated in following diagrams: Laser Beams Absorbing Plane Figure 1 In the calculation part, it has been calculated that there is a net force propelling the system, whose magnitude and direction depends upon the angle of inclined plane and power of lasers.

Calculations
Let F 1 be the Force produced on surface one due to firing of lasers F 2 be the net Force produced when lasers hit inclined plane and reflect F 3 be the Force produced on third surface F 4 be the force produced on third surface upon reflection of lasers F 5 be the net Force produced when lasers hit inclined plane and reflect F 6 be the force on absorbing surface when lasers are absorbed Now, This all is illustrated in following diagrams: *E-mail -jiveshadhlakha@gmail.comForce produced upon firing, reflecting, and absorbing of lasers normal to plane will be equal in magnitude.This gives: Force normal to inclined plane can be given as Fcos 2 α α is the angle of inclined plane with respect to lasers from surface As laser is reflected, so the net force will be 2Fcos 2 α

Now,
The lasers reflected from the third surface will fall on inclined reflecting plane to further apply a force 2Fcos 2 (90-α)=2Fsin 2 α Net force on the absorbing surface after one complete cycle of laser reflection will be F 1 +F 6 =2F Net force on the reflecting surface (third surface) after one complete cycle of laser reflection will be *E-mail -jiveshadhlakha@gmail.com To maximize the net force on inclined plane, let α =45 Therefore, net force will be 2Fcos 2 α +2Fsin 2 α = + =2F Resolving the force vector into its components gives:

Magnitude of force along x-axis= 2Fcos45 =√2F
Direction will be exactly opposite to the force applied on third surface, as shown in figure 2.

Magnitude of force along y-axis= 2Fcos45 =√2F
Direction will be exactly opposite to the force applied on first surface, as shown in figure 2.
Therefore, net force on the system after one laser cycle will be: Component along x-axis F r =2F-√2F=F(2-1.4)=.6F(approx..) √2=1.4 *E-mail -jiveshadhlakha@gmail.com Component along y-axis F p =2F-√2F=F(2-1.4)=.6F(approx..) Net Force Note that angle between F r and F p is 90 Therefore magnitude of net force on space craft will be Now, this gives 85% force to space craft, as opposed to direct laser propulsion.
However, this makes it more viable because in ideal setup, the lasers fired are being again converted to electrical potential and stored again, while still giving a net force of .85F.

Calculations for 300 Trillions watt lasers system
If lasers used are of combined power 3*10 14 watts, Force F will be F= =3*10 14 /3*10 8 =10 6 Newtons Net force on space craft F n =.85*10 6 =8.5*10 5 N Let mass of space craft be around 8500kg This will give an acceleration of 100ms -2 to a spacecraft of 8500kg mass.a=10 2 ms -2

Using classical non-modified equation of motion v=at
To reach one third the speed of light, the given system will take t=10 8 /10 2 =10 6 seconds, which is almost 11 and a half days.
*E-mail -jiveshadhlakha@gmail.com Calculations for 3000 Trillions watt lasers system and 4250 kg mass

Using classical non-modified equation of motion v=at
To reach one third the speed of light, the given system will take t=10 8 /2*10 3 t=50,000 seconds or 13.89 hours mail -jiveshadhlakha@gmail.com Figure 1