← INDEX — FIG. 00 — IKAROS, 14 × 14 M, 1.12 mN
2S/c = 9.08 µN/m²
SAIL
SOLAR SAILS
Light carries momentum.
BEGIN — CHAPTER 01 →CH.01 / 06 — MOMENTUM FROM PHOTONS
Nine micronewtons per square metre
S = 1,361 W/m²; 2S/c = 9.08 µN/m².
IKAROS: 1.12 mN measured.
SOLAR RADIATION PRESSURE ON A SAIL
F = η · (2S/c) · A · cos²α / r² · a = F/m
IKAROS: η·cos²α ≈ 0.63.
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Preset values and assumptions.
CH.02 / 06 — TACKING AGAINST THE SUN
Tilt about 35° to push sideways
Maximum at α ≈ 35.26°.
LightSail 2 raised its orbit with light.
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CH.03 / 06 — CLOSE TO THE SUN, STRONG; FAR AWAY, WEAK
A push that never stops adds up
1/r².
ACS3 and the end of IKAROS.
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Simple Δv = a·t.
CH.04 / 06 — LIGHT, THIN AND HUGE
Everything depends on grams per square metre
Areal density sets performance.
IKAROS steered with LCD panels.
CH.05 / 06 — SAILING BY LIGHT
Demonstrations, one piece at a time
The gentlest push, for as long as the Sun shines.
CH.06 / 06 — REFERENCES