Consider a solar sailcraft of total mass 10,000 kg , which uses a large, low-mas
ID: 2309163 • Letter: C
Question
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?
rSunEarth = 1.50 × 1011m
REarth = 6.37 × 106m
Explanation / Answer
Reflective
so that radiation force is maximized
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A > G m Msun 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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