Consider a solar sailcraft of total mass 10000 kg which uses

Consider a solar sailcraft of total mass 10,000 kg, which uses a large, low-mass sail and the energy and momentum of sunlight for propulsion.

(a) Should the sail be reflective or absorbing, and why?

(b) The total power output of Sun is 3.9 × 10²⁶W. How large a sail (express in km²) is needed to propel the craft against the gravitational force of Sun?

(c) Consider the total radiation power emitted by Sun as stated in the previous part. How much of this power is received by Earth?

r_SunEarth = 1.50 × 10¹¹m

R_Earth = 6.37 × 10⁶m

Solution

Reflective

so that radiation force is maximized

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A > G m M_sun 4 pi c / 2 P

= (4 * pi * 3 * 10⁸ * 6.67 * 10^-11 * 10000 * 1.99 * 10³⁰) / (2 * 3.9 * 10²⁶)

= 6.4 * 10⁶ m² = 6.4 km²

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