In: Physics
An entrepreneur has proposed sending a probe to Alpha Centai 4
light years away. His idea is to use a "solar sail", which is a
large area reflective sheet, and propelling the spacecraft to 10%
of the speed of light using a high powered laser. If the laser
sends 1200 nm light at the sail and the power reaching the
reflective sheet is 1500 W:
(a) What is the force due to light pressure on the reflective
sheet, assuming the light backscatters with 20% efficiency?
(b) If an engineer is testing the spacecraft far away from the
solar system so that the gravity of the sun and planets can be
ignored, and the spacecraft is 65 kg, what would be the power
necessary to achieve 10% of the speed of light if the acceleration
part of the journey was only 5.0 x 10^5 km? (ignore relativistic
effects)