Sun Synchronous Orbit (SSO)
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Molniya Orbits •
Molniya (HEO) orbits—named after the Russian word for lightning (as in “quick-as-lightning”) also use Earth’s oblateness to advantage. – Typically y y ~ 12-hour orbits with very y high g eccentricity y ((e = ~0.7)) and a perigee g location in the Southern Hemisphere. The inclination is 63.4°—why? – At this inclination the perigee doesn’t precess so the spacecraft “hangs” over the Northern Hemisphere for nearly 11 hours of its 12-hour period – The Russians (and others) use these orbits to provide coverage at high latitudes that can’t “see” satellites at GEO
US Fig. 8-13. © DO NOT REPRODUCE WITHOUT PERMISSION
Describing & Using Orbits - 32