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Newton’s thought experiment: orbital velocity. Surface escape velocities Planet V escape , ft/sec. Rocket Equation delta V = g I sp ln (M o /M f ) where: delta V = rocket velocity change (m/s) g = gravitational constant (9.81 m/s 2 )
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Newton’s thought experiment: orbital velocity
Surface escape velocities Planet Vescape, ft/sec
Rocket Equation delta V = g Isp ln (Mo/Mf) where: delta V = rocket velocity change (m/s) g = gravitational constant (9.81 m/s2) Isp = rocket specific impulse (s) Mo = initial rocket mass (kg) Mf = final rocket mass (kg) • Equation is for ideal conditions, with no strong gravity fields, as with near a planet. Corrections can be made by accounting for gravity “losses.”
ORBITING SATELLITES Vehicle range Burnout velocity (thousands of ft/sec)
Earth Orbit Definitions • Apogee: the farthest point from the Earth. • Perigee: the closest point to the Earth. Because of the Earth's atmosphere, this cannot be less than about 80 miles above the surface. • For circular orbits, the apogee and perigee are the same. • Period: the time it takes to go around the Earth once. (The apogee and perigee determine the period.) • Inclination: the angle the orbital plane makes with the Earth's equatorial plane.